server: Disallow ServeConn usage after Shutdown

This reverts commit 48c67bcead.

.build.yml

@@ -0,0 +1,9 @@
+image: alpine/edge
+packages:
+- go
+sources:
+- https://git.sr.ht/~adnano/go-gemini
+tasks:
+- test: |
+    cd go-gemini
+    go test ./...

.gitignore

@@ -1,2 +0,0 @@
-*.crt
-*.key

README.md

@@ -1,10 +1,12 @@
 # go-gemini
 
-[![GoDoc](https://godoc.org/git.sr.ht/~adnano/go-gemini?status.svg)](https://godoc.org/git.sr.ht/~adnano/go-gemini)
+[![godocs.io](https://godocs.io/git.sr.ht/~adnano/go-gemini?status.svg)](https://godocs.io/git.sr.ht/~adnano/go-gemini) [![builds.sr.ht status](https://builds.sr.ht/~adnano/go-gemini.svg)](https://builds.sr.ht/~adnano/go-gemini?)
 
 Package gemini implements the [Gemini protocol](https://gemini.circumlunar.space) in Go.
 
-It aims to provide an API similar to that of net/http to make it easy to develop Gemini clients and servers.
+It provides an API similar to that of net/http to make it easy to develop Gemini clients and servers.
+
+Compatible with version v0.14.3 of the Gemini specification.
 
 ## Usage
 

certificate/create.go

@@ -1,4 +1,5 @@
-package gemini
+// Package certificate provides functions for creating and storing TLS certificates.
+package certificate
 
 import (
 	"crypto"
@@ -13,102 +14,20 @@ import (
 	"math/big"
 	"net"
 	"os"
-	"path/filepath"
-	"strings"
 	"time"
 )
 
-// CertificateDir maps certificate scopes to certificates.
+// CreateOptions configures the creation of a TLS certificate.
-type CertificateStore map[string]tls.Certificate
+type CreateOptions struct {
-
-// CertificateDir represents a certificate store optionally loaded from a directory.
-// The zero value of CertificateDir is an empty store ready to use.
-type CertificateDir struct {
-	CertificateStore
-	dir  bool
-	path string
-}
-
-// Add adds a certificate for the given scope to the store.
-// It tries to parse the certificate if it is not already parsed.
-func (c *CertificateDir) Add(scope string, cert tls.Certificate) {
-	if c.CertificateStore == nil {
-		c.CertificateStore = CertificateStore{}
-	}
-	// Parse certificate if not already parsed
-	if cert.Leaf == nil {
-		parsed, err := x509.ParseCertificate(cert.Certificate[0])
-		if err == nil {
-			cert.Leaf = parsed
-		}
-	}
-	c.CertificateStore[scope] = cert
-}
-
-// Write writes the provided certificate to the certificate directory.
-func (c *CertificateDir) Write(scope string, cert tls.Certificate) error {
-	if c.dir {
-		// Escape slash character
-		scope = strings.ReplaceAll(scope, "/", ":")
-		certPath := filepath.Join(c.path, scope+".crt")
-		keyPath := filepath.Join(c.path, scope+".key")
-		if err := WriteCertificate(cert, certPath, keyPath); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// Lookup returns the certificate for the given scope.
-func (c *CertificateDir) Lookup(scope string) (tls.Certificate, bool) {
-	cert, ok := c.CertificateStore[scope]
-	return cert, ok
-}
-
-// Load loads certificates from the given path.
-// The path should lead to a directory containing certificates and private keys
-// in the form scope.crt and scope.key.
-// For example, the hostname "localhost" would have the corresponding files
-// localhost.crt (certificate) and localhost.key (private key).
-// New certificates will be written to this directory.
-func (c *CertificateDir) Load(path string) error {
-	matches, err := filepath.Glob(filepath.Join(path, "*.crt"))
-	if err != nil {
-		return err
-	}
-	for _, crtPath := range matches {
-		keyPath := strings.TrimSuffix(crtPath, ".crt") + ".key"
-		cert, err := tls.LoadX509KeyPair(crtPath, keyPath)
-		if err != nil {
-			continue
-		}
-		scope := strings.TrimSuffix(filepath.Base(crtPath), ".crt")
-		// Unescape slash character
-		scope = strings.ReplaceAll(scope, ":", "/")
-		c.Add(scope, cert)
-	}
-	c.dir = true
-	c.path = path
-	return nil
-}
-
-// SetDir sets the directory that new certificates will be written to.
-func (c *CertificateDir) SetDir(path string) {
-	c.dir = true
-	c.path = path
-}
-
-// CertificateOptions configures the creation of a certificate.
-type CertificateOptions struct {
-	// Subject Alternate Name values.
-	// Should contain the IP addresses that the certificate is valid for.
-	IPAddresses []net.IP
-
 	// Subject Alternate Name values.
 	// Should contain the DNS names that this certificate is valid for.
 	// E.g. example.com, *.example.com
 	DNSNames []string
 
+	// Subject Alternate Name values.
+	// Should contain the IP addresses that the certificate is valid for.
+	IPAddresses []net.IP
+
 	// Subject specifies the certificate Subject.
 	//
 	// Subject.CommonName can contain the DNS name that this certificate
@@ -125,8 +44,8 @@ type CertificateOptions struct {
 	Ed25519 bool
 }
 
-// CreateCertificate creates a new TLS certificate.
+// Create creates a new TLS certificate.
-func CreateCertificate(options CertificateOptions) (tls.Certificate, error) {
+func Create(options CreateOptions) (tls.Certificate, error) {
 	crt, priv, err := newX509KeyPair(options)
 	if err != nil {
 		return tls.Certificate{}, err
@@ -139,7 +58,7 @@ func CreateCertificate(options CertificateOptions) (tls.Certificate, error) {
 }
 
 // newX509KeyPair creates and returns a new certificate and private key.
-func newX509KeyPair(options CertificateOptions) (*x509.Certificate, crypto.PrivateKey, error) {
+func newX509KeyPair(options CreateOptions) (*x509.Certificate, crypto.PrivateKey, error) {
 	var pub crypto.PublicKey
 	var priv crypto.PrivateKey
 	if options.Ed25519 {
@@ -195,9 +114,9 @@ func newX509KeyPair(options CertificateOptions) (*x509.Certificate, crypto.Priva
 	return cert, priv, nil
 }
 
-// WriteCertificate writes the provided certificate and private key
+// Write writes the provided certificate and its private key
 // to certPath and keyPath respectively.
-func WriteCertificate(cert tls.Certificate, certPath, keyPath string) error {
+func Write(cert tls.Certificate, certPath, keyPath string) error {
 	certOut, err := os.OpenFile(certPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
 		return err

certificate/store.go

@@ -0,0 +1,174 @@
+package certificate
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"errors"
+	"fmt"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+)
+
+// A Store represents a certificate store.
+// It generates certificates as needed and automatically rotates expired certificates.
+// The zero value for Store is an empty store ready to use.
+//
+// Certificate scopes must be registered with Register before calling Get or Load.
+// This prevents the Store from creating or loading unnecessary certificates.
+//
+// Store is safe for concurrent use by multiple goroutines.
+type Store struct {
+	// CreateCertificate, if not nil, is called to create a new certificate
+	// to replace a missing or expired certificate. If CreateCertificate
+	// is nil, a certificate with a duration of 1 year will be created.
+	// The provided scope is suitable for use in a certificate's DNSNames.
+	CreateCertificate func(scope string) (tls.Certificate, error)
+
+	certs map[string]tls.Certificate
+	path  string
+	mu    sync.RWMutex
+}
+
+// Register registers the provided scope with the certificate store.
+// The scope can either be a hostname or a wildcard pattern (e.g. "*.example.com").
+// To accept all hostnames, use the special pattern "*".
+func (s *Store) Register(scope string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.certs == nil {
+		s.certs = make(map[string]tls.Certificate)
+	}
+	s.certs[scope] = tls.Certificate{}
+}
+
+// Add adds a certificate with the given scope to the certificate store.
+// If a certificate for the given scope already exists, Add will overwrite it.
+func (s *Store) Add(scope string, cert tls.Certificate) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.certs == nil {
+		s.certs = make(map[string]tls.Certificate)
+	}
+
+	// Parse certificate if not already parsed
+	if cert.Leaf == nil {
+		parsed, err := x509.ParseCertificate(cert.Certificate[0])
+		if err != nil {
+			return err
+		}
+		cert.Leaf = parsed
+	}
+
+	if s.path != "" {
+		certPath := filepath.Join(s.path, scope+".crt")
+		keyPath := filepath.Join(s.path, scope+".key")
+		if err := Write(cert, certPath, keyPath); err != nil {
+			return err
+		}
+	}
+
+	s.certs[scope] = cert
+	return nil
+}
+
+// Get retrieves a certificate for the given hostname.
+// If no matching scope has been registered, Get returns an error.
+// Get generates new certificates as needed and rotates expired certificates.
+//
+// Get is suitable for use in a gemini.Server's GetCertificate field.
+func (s *Store) Get(hostname string) (*tls.Certificate, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	cert, ok := s.certs[hostname]
+	if !ok {
+		// Try wildcard
+		wildcard := strings.SplitN(hostname, ".", 2)
+		if len(wildcard) == 2 {
+			hostname = "*." + wildcard[1]
+			cert, ok = s.certs[hostname]
+		}
+	}
+	if !ok {
+		// Try "*"
+		cert, ok = s.certs["*"]
+	}
+	if !ok {
+		return nil, errors.New("unrecognized scope")
+	}
+
+	// If the certificate is empty or expired, generate a new one.
+	if cert.Leaf == nil || cert.Leaf.NotAfter.Before(time.Now()) {
+		var err error
+		cert, err = s.createCertificate(hostname)
+		if err != nil {
+			return nil, err
+		}
+		if err := s.Add(hostname, cert); err != nil {
+			return nil, fmt.Errorf("failed to add certificate for %s: %w", hostname, err)
+		}
+	}
+
+	return &cert, nil
+}
+
+func (s *Store) createCertificate(scope string) (tls.Certificate, error) {
+	if s.CreateCertificate != nil {
+		return s.CreateCertificate(scope)
+	}
+	return Create(CreateOptions{
+		DNSNames: []string{scope},
+		Subject: pkix.Name{
+			CommonName: scope,
+		},
+		Duration: 365 * 24 * time.Hour,
+	})
+}
+
+// Load loads certificates from the provided path.
+// New certificates will be written to this path.
+// The path should lead to a directory containing certificates
+// and private keys named "scope.crt" and "scope.key" respectively,
+// where "scope" is the scope of the certificate.
+// Certificates with scopes that have not been registered will be ignored.
+func (s *Store) Load(path string) error {
+	matches, err := filepath.Glob(filepath.Join(path, "*.crt"))
+	if err != nil {
+		return err
+	}
+	for _, crtPath := range matches {
+		scope := strings.TrimSuffix(filepath.Base(crtPath), ".crt")
+		if _, ok := s.certs[scope]; !ok {
+			continue
+		}
+
+		keyPath := strings.TrimSuffix(crtPath, ".crt") + ".key"
+		cert, err := tls.LoadX509KeyPair(crtPath, keyPath)
+		if err != nil {
+			continue
+		}
+		s.Add(scope, cert)
+	}
+	s.SetPath(path)
+	return nil
+}
+
+// Entries returns a map of scopes to certificates.
+func (s *Store) Entries() map[string]tls.Certificate {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	certs := make(map[string]tls.Certificate)
+	for key := range s.certs {
+		certs[key] = s.certs[key]
+	}
+	return certs
+}
+
+// SetPath sets the path that new certificates will be written to.
+func (s *Store) SetPath(path string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.path = path
+}

client.go

@@ -1,257 +1,223 @@
 package gemini
 
 import (
-	"bufio"
+	"context"
 	"crypto/tls"
 	"crypto/x509"
-	"errors"
 	"net"
 	"net/url"
-	"path"
-	"strings"
-	"sync"
 	"time"
+	"unicode/utf8"
+
+	"golang.org/x/net/idna"
 )
 
-// Client is a Gemini client.
+// A Client is a Gemini client. Its zero value is a usable client.
-//
-// Clients are safe for concurrent use by multiple goroutines.
 type Client struct {
-	// KnownHosts is a list of known hosts.
+	// TrustCertificate is called to determine whether the client should
-	KnownHosts KnownHostsFile
+	// trust the certificate provided by the server.
-
+	// If TrustCertificate is nil or returns nil, the client will accept
-	// Certificates stores client-side certificates.
+	// any certificate. Otherwise, the certificate will not be trusted
-	Certificates CertificateDir
+	// and the request will be aborted.
-
-	// Timeout specifies a time limit for requests made by this
-	// Client. The timeout includes connection time and reading
-	// the response body. The timer remains running after
-	// Get and Do return and will interrupt reading of the Response.Body.
 	//
-	// A Timeout of zero means no timeout.
+	// See the tofu submodule for an implementation of trust on first use.
-	Timeout time.Duration
+	TrustCertificate func(hostname string, cert *x509.Certificate) error
 
-	// InsecureSkipTrust specifies whether the client should trust
+	// DialContext specifies the dial function for creating TCP connections.
-	// any certificate it receives without checking KnownHosts
+	// If DialContext is nil, the client dials using package net.
-	// or calling TrustCertificate.
+	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
-	// Use with caution.
-	InsecureSkipTrust bool
-
-	// GetInput is called to retrieve input when the server requests it.
-	// If GetInput is nil or returns false, no input will be sent and
-	// the response will be returned.
-	GetInput func(prompt string, sensitive bool) (input string, ok bool)
-
-	// CheckRedirect determines whether to follow a redirect.
-	// If CheckRedirect is nil, redirects will not be followed.
-	CheckRedirect func(req *Request, via []*Request) error
-
-	// CreateCertificate is called to generate a certificate upon
-	// the request of a server.
-	// If CreateCertificate is nil or the returned error is not nil,
-	// the request will not be sent again and the response will be returned.
-	CreateCertificate func(scope, path string) (tls.Certificate, error)
-
-	// TrustCertificate is called to determine whether the client
-	// should trust a certificate it has not seen before.
-	// If TrustCertificate is nil, the certificate will not be trusted
-	// and the connection will be aborted.
-	//
-	// If TrustCertificate returns TrustOnce, the certificate will be added
-	// to the client's list of known hosts.
-	// If TrustCertificate returns TrustAlways, the certificate will also be
-	// written to the known hosts file.
-	TrustCertificate func(hostname string, cert *x509.Certificate) Trust
-
-	mu sync.Mutex
 }
 
-// Get performs a Gemini request for the given url.
+// Get sends a Gemini request for the given URL.
-func (c *Client) Get(url string) (*Response, error) {
+// The context controls the entire lifetime of a request and its response:
+// obtaining a connection, sending the request, and reading the response
+// header and body.
+//
+// An error is returned if there was a Gemini protocol error.
+// A non-2x status code doesn't cause an error.
+//
+// If the returned error is nil, the user is expected to close the Response.
+//
+// For more control over requests, use NewRequest and Client.Do.
+func (c *Client) Get(ctx context.Context, url string) (*Response, error) {
 	req, err := NewRequest(url)
 	if err != nil {
 		return nil, err
 	}
-	return c.Do(req)
+	return c.Do(ctx, req)
 }
 
-// Do performs a Gemini request and returns a Gemini response.
+// Do sends a Gemini request and returns a Gemini response.
-func (c *Client) Do(req *Request) (*Response, error) {
+// The context controls the entire lifetime of a request and its response:
-	c.mu.Lock()
+// obtaining a connection, sending the request, and reading the response
-	defer c.mu.Unlock()
+// header and body.
-
+//
-	return c.do(req, nil)
+// An error is returned if there was a Gemini protocol error.
-}
+// A non-2x status code doesn't cause an error.
-
+//
-func (c *Client) do(req *Request, via []*Request) (*Response, error) {
+// If the returned error is nil, the user is expected to close the Response.
-	// Extract hostname
+func (c *Client) Do(ctx context.Context, req *Request) (*Response, error) {
-	colonPos := strings.LastIndex(req.Host, ":")
+	if ctx == nil {
-	if colonPos == -1 {
+		panic("nil context")
-		colonPos = len(req.Host)
 	}
-	hostname := req.Host[:colonPos]
 
-	// Connect to the host
+	// Punycode request URL host
-	config := &tls.Config{
+	host, port := splitHostPort(req.URL.Host)
-		InsecureSkipVerify: true,
+	punycode, err := punycodeHostname(host)
-		MinVersion:         tls.VersionTLS12,
-		GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
-			return c.getClientCertificate(req)
-		},
-		VerifyConnection: func(cs tls.ConnectionState) error {
-			return c.verifyConnection(req, cs)
-		},
-		ServerName: hostname,
-	}
-	netConn, err := (&net.Dialer{}).DialContext(req.Context, "tcp", req.Host)
 	if err != nil {
 		return nil, err
 	}
-	conn := tls.Client(netConn, config)
+	if host != punycode {
-	// Set connection deadline
+		host = punycode
-	if d := c.Timeout; d != 0 {
+
-		conn.SetDeadline(time.Now().Add(d))
+		// Copy the URL and update the host
+		u := new(url.URL)
+		*u = *req.URL
+		u.Host = net.JoinHostPort(host, port)
+
+		// Use the new URL in the request so that the server gets
+		// the punycoded hostname
+		r := new(Request)
+		*r = *req
+		r.URL = u
+		req = r
+	}
+
+	// Use request host if provided
+	if req.Host != "" {
+		host, port = splitHostPort(req.Host)
+		host, err = punycodeHostname(host)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	addr := net.JoinHostPort(host, port)
+
+	// Connect to the host
+	conn, err := c.dialContext(ctx, "tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	// Setup TLS
+	conn = tls.Client(conn, &tls.Config{
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS12,
+		GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
+			if req.Certificate != nil {
+				return req.Certificate, nil
+			}
+			return &tls.Certificate{}, nil
+		},
+		VerifyConnection: func(cs tls.ConnectionState) error {
+			return c.verifyConnection(cs, host)
+		},
+		ServerName: host,
+	})
+
+	type result struct {
+		resp *Response
+		err  error
+	}
+
+	res := make(chan result, 1)
+	go func() {
+		resp, err := c.do(ctx, conn, req)
+		res <- result{resp, err}
+	}()
+
+	select {
+	case <-ctx.Done():
+		conn.Close()
+		return nil, ctx.Err()
+	case r := <-res:
+		return r.resp, r.err
+	}
+}
+
+func (c *Client) do(ctx context.Context, conn net.Conn, req *Request) (*Response, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	done := ctx.Done()
+	w := &contextWriter{
+		ctx:    ctx,
+		done:   done,
+		cancel: cancel,
+		wc:     conn,
+	}
+	rc := &contextReader{
+		ctx:    ctx,
+		done:   done,
+		cancel: cancel,
+		rc:     conn,
 	}
 
 	// Write the request
-	w := bufio.NewWriter(conn)
+	if err := req.Write(w); err != nil {
-	req.write(w)
-	if err := w.Flush(); err != nil {
 		return nil, err
 	}
 
 	// Read the response
-	resp := &Response{}
+	resp, err := ReadResponse(rc)
-	if err := resp.read(conn); err != nil {
+	if err != nil {
 		return nil, err
 	}
-	resp.Request = req
+	resp.conn = conn
-	// Store connection state
-	resp.TLS = conn.ConnectionState()
-
-	switch {
-	case resp.Status == StatusCertificateRequired:
-		// Check to see if a certificate was already provided to prevent an infinite loop
-		if req.Certificate != nil {
-			return resp, nil
-		}
-
-		hostname, path := req.URL.Hostname(), strings.TrimSuffix(req.URL.Path, "/")
-		if c.CreateCertificate != nil {
-			cert, err := c.CreateCertificate(hostname, path)
-			if err != nil {
-				return resp, err
-			}
-			c.Certificates.Add(hostname+path, cert)
-			c.Certificates.Write(hostname+path, cert)
-			req.Certificate = &cert
-			return c.do(req, via)
-		}
-		return resp, nil
-
-	case resp.Status.Class() == StatusClassInput:
-		if c.GetInput != nil {
-			input, ok := c.GetInput(resp.Meta, resp.Status == StatusSensitiveInput)
-			if ok {
-				req.URL.ForceQuery = true
-				req.URL.RawQuery = QueryEscape(input)
-				return c.do(req, via)
-			}
-		}
-		return resp, nil
-
-	case resp.Status.Class() == StatusClassRedirect:
-		if via == nil {
-			via = []*Request{}
-		}
-		via = append(via, req)
-
-		target, err := url.Parse(resp.Meta)
-		if err != nil {
-			return resp, err
-		}
-		target = req.URL.ResolveReference(target)
-
-		redirect := NewRequestFromURL(target)
-		redirect.Context = req.Context
-		if c.CheckRedirect != nil {
-			if err := c.CheckRedirect(redirect, via); err != nil {
-				return resp, err
-			}
-			return c.do(redirect, via)
-		}
-	}
 
 	return resp, nil
 }
 
-func (c *Client) getClientCertificate(req *Request) (*tls.Certificate, error) {
+func (c *Client) dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	// Request certificates have the highest precedence
+	if c.DialContext != nil {
-	if req.Certificate != nil {
+		return c.DialContext(ctx, network, addr)
-		return req.Certificate, nil
 	}
-
+	return (&net.Dialer{}).DialContext(ctx, network, addr)
-	// Search recursively for the certificate
-	scope := req.URL.Hostname() + strings.TrimSuffix(req.URL.Path, "/")
-	for {
-		cert, ok := c.Certificates.Lookup(scope)
-		if ok {
-			// Ensure that the certificate is not expired
-			if cert.Leaf != nil && !time.Now().After(cert.Leaf.NotAfter) {
-				// Store the certificate
-				req.Certificate = &cert
-				return &cert, nil
-			}
-			break
-		}
-		scope = path.Dir(scope)
-		if scope == "." {
-			break
-		}
-	}
-
-	return &tls.Certificate{}, nil
 }
 
-func (c *Client) verifyConnection(req *Request, cs tls.ConnectionState) error {
+func (c *Client) verifyConnection(cs tls.ConnectionState, hostname string) error {
-	// Verify the hostname
-	var hostname string
-	if host, _, err := net.SplitHostPort(req.Host); err == nil {
-		hostname = host
-	} else {
-		hostname = req.Host
-	}
 	cert := cs.PeerCertificates[0]
+	// Verify hostname
 	if err := verifyHostname(cert, hostname); err != nil {
 		return err
 	}
-	if c.InsecureSkipTrust {
+	// Check expiration date
-		return nil
+	if !time.Now().Before(cert.NotAfter) {
+		return ErrCertificateExpired
 	}
-
+	// See if the client trusts the certificate
-	// Check the known hosts
+	if c.TrustCertificate != nil {
-	knownHost, ok := c.KnownHosts.Lookup(hostname)
+		return c.TrustCertificate(hostname, cert)
-	if !ok || !time.Now().Before(knownHost.Expires) {
-		// See if the client trusts the certificate
-		if c.TrustCertificate != nil {
-			switch c.TrustCertificate(hostname, cert) {
-			case TrustOnce:
-				fingerprint := NewFingerprint(cert.Raw, cert.NotAfter)
-				c.KnownHosts.Add(hostname, fingerprint)
-				return nil
-			case TrustAlways:
-				fingerprint := NewFingerprint(cert.Raw, cert.NotAfter)
-				c.KnownHosts.Add(hostname, fingerprint)
-				c.KnownHosts.Write(hostname, fingerprint)
-				return nil
-			}
-		}
-		return errors.New("gemini: certificate not trusted")
 	}
-
+	return nil
-	fingerprint := NewFingerprint(cert.Raw, cert.NotAfter)
+}
-	if knownHost.Hex == fingerprint.Hex {
+
-		return nil
+func splitHostPort(hostport string) (host, port string) {
-	}
+	var err error
-	return errors.New("gemini: fingerprint does not match")
+	host, port, err = net.SplitHostPort(hostport)
+	if err != nil {
+		// Likely no port
+		host = hostport
+		port = "1965"
+	}
+	return
+}
+
+func isASCII(s string) bool {
+	for i := 0; i < len(s); i++ {
+		if s[i] >= utf8.RuneSelf {
+			return false
+		}
+	}
+	return true
+}
+
+// punycodeHostname returns the punycoded version of hostname.
+func punycodeHostname(hostname string) (string, error) {
+	if net.ParseIP(hostname) != nil {
+		return hostname, nil
+	}
+	if isASCII(hostname) {
+		return hostname, nil
+	}
+	return idna.Lookup.ToASCII(hostname)
 }

doc.go

@@ -0,0 +1,55 @@
+/*
+Package gemini provides Gemini client and server implementations.
+
+Client is a Gemini client.
+
+	client := &gemini.Client{}
+	ctx := context.Background()
+	resp, err := client.Get(ctx, "gemini://example.com")
+	if err != nil {
+		// handle error
+	}
+	defer resp.Body.Close()
+	// ...
+
+Server is a Gemini server.
+
+	server := &gemini.Server{
+		ReadTimeout:  10 * time.Second,
+		WriteTimeout: 10 * time.Second,
+	}
+
+Servers should be configured with certificates:
+
+	certificates := &certificate.Store{}
+	certificates.Register("localhost")
+	err := certificates.Load("/var/lib/gemini/certs")
+	if err != nil {
+		// handle error
+	}
+	server.GetCertificate = certificates.Get
+
+ServeMux is a Gemini request multiplexer.
+ServeMux can handle requests for multiple hosts and schemes.
+
+	mux := &gemini.ServeMux{}
+	mux.HandleFunc("example.com", func(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
+		fmt.Fprint(w, "Welcome to example.com")
+	})
+	mux.HandleFunc("example.org/about.gmi", func(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
+		fmt.Fprint(w, "About example.org")
+	})
+	mux.HandleFunc("http://example.net", func(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
+		fmt.Fprint(w, "Proxied content from http://example.net")
+	})
+	server.Handler = mux
+
+To start the server, call ListenAndServe:
+
+	ctx := context.Background()
+	err := server.ListenAndServe(ctx)
+	if err != nil {
+		// handle error
+	}
+*/
+package gemini

examples/auth.go

@@ -3,15 +3,15 @@
 package main
 
 import (
+	"context"
 	"crypto/sha512"
-	"crypto/tls"
 	"crypto/x509"
-	"crypto/x509/pkix"
 	"fmt"
 	"log"
 	"time"
 
 	"git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini/certificate"
 )
 
 type User struct {
@@ -24,26 +24,24 @@ var (
 )
 
 func main() {
-	var mux gemini.ServeMux
+	certificates := &certificate.Store{}
+	certificates.Register("localhost")
+	if err := certificates.Load("/var/lib/gemini/certs"); err != nil {
+		log.Fatal(err)
+	}
+
+	mux := &gemini.ServeMux{}
 	mux.HandleFunc("/", profile)
 	mux.HandleFunc("/username", changeUsername)
 
-	var server gemini.Server
+	server := &gemini.Server{
-	if err := server.Certificates.Load("/var/lib/gemini/certs"); err != nil {
+		Handler:        mux,
-		log.Fatal(err)
+		ReadTimeout:    30 * time.Second,
+		WriteTimeout:   1 * time.Minute,
+		GetCertificate: certificates.Get,
 	}
-	server.CreateCertificate = func(hostname string) (tls.Certificate, error) {
-		return gemini.CreateCertificate(gemini.CertificateOptions{
-			Subject: pkix.Name{
-				CommonName: hostname,
-			},
-			DNSNames: []string{hostname},
-			Duration: time.Hour,
-		})
-	}
-	server.Register("localhost", &mux)
 
-	if err := server.ListenAndServe(); err != nil {
+	if err := server.ListenAndServe(context.Background()); err != nil {
 		log.Fatal(err)
 	}
 }
@@ -53,12 +51,13 @@ func fingerprint(cert *x509.Certificate) string {
 	return string(b[:])
 }
 
-func profile(w *gemini.ResponseWriter, r *gemini.Request) {
+func profile(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
-	if r.Certificate == nil {
+	tls := r.TLS()
-		w.WriteStatus(gemini.StatusCertificateRequired)
+	if len(tls.PeerCertificates) == 0 {
+		w.WriteHeader(gemini.StatusCertificateRequired, "Certificate required")
 		return
 	}
-	fingerprint := fingerprint(r.Certificate.Leaf)
+	fingerprint := fingerprint(tls.PeerCertificates[0])
 	user, ok := users[fingerprint]
 	if !ok {
 		user = &User{}
@@ -68,17 +67,24 @@ func profile(w *gemini.ResponseWriter, r *gemini.Request) {
 	fmt.Fprintln(w, "=> /username Change username")
 }
 
-func changeUsername(w *gemini.ResponseWriter, r *gemini.Request) {
+func changeUsername(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
-	if r.Certificate == nil {
+	tls := r.TLS()
-		w.WriteStatus(gemini.StatusCertificateRequired)
+	if len(tls.PeerCertificates) == 0 {
+		w.WriteHeader(gemini.StatusCertificateRequired, "Certificate required")
 		return
 	}
 
-	username, ok := gemini.Input(r)
+	username, err := gemini.QueryUnescape(r.URL.RawQuery)
-	if !ok {
+	if err != nil || username == "" {
 		w.WriteHeader(gemini.StatusInput, "Username")
 		return
 	}
-	users[fingerprint(r.Certificate.Leaf)].Name = username
+	fingerprint := fingerprint(tls.PeerCertificates[0])
+	user, ok := users[fingerprint]
+	if !ok {
+		user = &User{}
+		users[fingerprint] = user
+	}
+	user.Name = username
 	w.WriteHeader(gemini.StatusRedirect, "/")
 }

examples/cert.go

@@ -1,5 +1,7 @@
 // +build ignore
 
+// This example illustrates a certificate generation tool.
+
 package main
 
 import (
@@ -9,7 +11,7 @@ import (
 	"os"
 	"time"
 
-	"git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini/certificate"
 )
 
 func main() {
@@ -22,20 +24,20 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	options := gemini.CertificateOptions{
+	options := certificate.CreateOptions{
 		Subject: pkix.Name{
 			CommonName: host,
 		},
 		DNSNames: []string{host},
 		Duration: duration,
 	}
-	cert, err := gemini.CreateCertificate(options)
+	cert, err := certificate.Create(options)
 	if err != nil {
 		log.Fatal(err)
 	}
 	certPath := host + ".crt"
 	keyPath := host + ".key"
-	if err := gemini.WriteCertificate(cert, certPath, keyPath); err != nil {
+	if err := certificate.Write(cert, certPath, keyPath); err != nil {
 		log.Fatal(err)
 	}
 }

examples/client.go

@@ -1,22 +1,56 @@
 // +build ignore
 
+// This example illustrates a Gemini client.
+
 package main
 
 import (
 	"bufio"
-	"crypto/tls"
+	"bytes"
+	"context"
 	"crypto/x509"
+	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
+	"net/url"
 	"os"
 	"path/filepath"
 	"time"
 
 	"git.sr.ht/~adnano/go-gemini"
-	"git.sr.ht/~adnano/go-xdg"
+	"git.sr.ht/~adnano/go-gemini/tofu"
 )
 
+var (
+	hosts     tofu.KnownHosts
+	hostsfile *tofu.HostWriter
+	scanner   *bufio.Scanner
+)
+
+func xdgDataHome() string {
+	if s, ok := os.LookupEnv("XDG_DATA_HOME"); ok {
+		return s
+	}
+	return filepath.Join(os.Getenv("HOME"), ".local", "share")
+}
+
+func init() {
+	// Load known hosts file
+	path := filepath.Join(xdgDataHome(), "gemini", "known_hosts")
+	err := hosts.Load(path)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	hostsfile, err = tofu.OpenHostsFile(path)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	scanner = bufio.NewScanner(os.Stdin)
+}
+
 const trustPrompt = `The certificate offered by %s is of unknown trust. Its fingerprint is:
 %s
 
@@ -26,49 +60,87 @@ Otherwise, this should be safe to trust.
 [t]rust always; trust [o]nce; [a]bort
 => `
 
-var (
+func trustCertificate(hostname string, cert *x509.Certificate) error {
-	scanner = bufio.NewScanner(os.Stdin)
+	host := tofu.NewHost(hostname, cert.Raw, cert.NotAfter)
-	client  = &gemini.Client{}
-)
 
-func init() {
+	knownHost, ok := hosts.Lookup(hostname)
-	client.Timeout = 30 * time.Second
+	if ok && time.Now().Before(knownHost.Expires) {
-	client.KnownHosts.Load(filepath.Join(xdg.DataHome(), "gemini", "known_hosts"))
+		// Check fingerprint
-	client.TrustCertificate = func(hostname string, cert *x509.Certificate) gemini.Trust {
+		if bytes.Equal(knownHost.Fingerprint, host.Fingerprint) {
-		fingerprint := gemini.NewFingerprint(cert.Raw, cert.NotAfter)
+			return nil
-		fmt.Printf(trustPrompt, hostname, fingerprint.Hex)
-		scanner.Scan()
-		switch scanner.Text() {
-		case "t":
-			return gemini.TrustAlways
-		case "o":
-			return gemini.TrustOnce
-		default:
-			return gemini.TrustNone
 		}
+		return errors.New("error: fingerprint does not match!")
 	}
-	client.CreateCertificate = func(hostname, path string) (tls.Certificate, error) {
+
-		fmt.Println("Generating client certificate for", hostname, path)
+	fmt.Printf(trustPrompt, hostname, host.Fingerprint)
-		return gemini.CreateCertificate(gemini.CertificateOptions{
+	scanner.Scan()
-			Duration: time.Hour,
+	switch scanner.Text() {
-		})
+	case "t":
+		hosts.Add(host)
+		hostsfile.WriteHost(host)
+		return nil
+	case "o":
+		hosts.Add(host)
+		return nil
+	default:
+		return errors.New("certificate not trusted")
 	}
-	client.GetInput = func(prompt string, sensitive bool) (string, bool) {
+}
-		fmt.Printf("%s: ", prompt)
+
-		scanner.Scan()
+func getInput(prompt string, sensitive bool) (input string, ok bool) {
-		return scanner.Text(), true
+	fmt.Printf("%s ", prompt)
+	scanner.Scan()
+	return scanner.Text(), true
+}
+
+func do(req *gemini.Request, via []*gemini.Request) (*gemini.Response, error) {
+	client := gemini.Client{
+		TrustCertificate: trustCertificate,
 	}
+	ctx := context.Background()
+	resp, err := client.Do(ctx, req)
+	if err != nil {
+		return resp, err
+	}
+
+	switch resp.Status.Class() {
+	case gemini.StatusInput:
+		input, ok := getInput(resp.Meta, resp.Status == gemini.StatusSensitiveInput)
+		if !ok {
+			break
+		}
+		req.URL.ForceQuery = true
+		req.URL.RawQuery = gemini.QueryEscape(input)
+		return do(req, via)
+
+	case gemini.StatusRedirect:
+		via = append(via, req)
+		if len(via) > 5 {
+			return resp, errors.New("too many redirects")
+		}
+
+		target, err := url.Parse(resp.Meta)
+		if err != nil {
+			return resp, err
+		}
+		target = req.URL.ResolveReference(target)
+		redirect := *req
+		redirect.URL = target
+		return do(&redirect, via)
+	}
+
+	return resp, err
 }
 
 func main() {
 	if len(os.Args) < 2 {
-		fmt.Printf("usage: %s gemini://... [host]", os.Args[0])
+		fmt.Printf("usage: %s <url> [host]\n", os.Args[0])
 		os.Exit(1)
 	}
 
+	// Do the request
 	url := os.Args[1]
 	req, err := gemini.NewRequest(url)
-
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
@@ -76,21 +148,21 @@ func main() {
 	if len(os.Args) == 3 {
 		req.Host = os.Args[2]
 	}
-
+	resp, err := do(req, nil)
-	resp, err := client.Do(req)
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
+	defer resp.Body.Close()
 
-	if resp.Status.Class() == gemini.StatusClassSuccess {
+	// Handle response
-		defer resp.Body.Close()
+	if resp.Status.Class() == gemini.StatusSuccess {
-		body, err := ioutil.ReadAll(resp.Body)
+		_, err := io.Copy(os.Stdout, resp.Body)
 		if err != nil {
 			log.Fatal(err)
 		}
-		fmt.Print(string(body))
 	} else {
-		fmt.Printf("request failed: %d %s: %s", resp.Status, resp.Status.Message(), resp.Meta)
+		fmt.Printf("%d %s\n", resp.Status, resp.Meta)
+		os.Exit(1)
 	}
 }

examples/html.go

@@ -7,76 +7,77 @@ package main
 import (
 	"fmt"
 	"html"
-	"strings"
+	"io"
+	"os"
 
 	"git.sr.ht/~adnano/go-gemini"
 )
 
 func main() {
-	text := gemini.Text{
+	hw := HTMLWriter{
-		gemini.LineHeading1("Hello, world!"),
+		out: os.Stdout,
-		gemini.LineText("This is a gemini text document."),
 	}
-
+	gemini.ParseLines(os.Stdin, hw.Handle)
-	html := textToHTML(text)
+	hw.Finish()
-	fmt.Print(html)
 }
 
-// textToHTML returns the Gemini text response as HTML.
+type HTMLWriter struct {
-func textToHTML(text gemini.Text) string {
+	out  io.Writer
-	var b strings.Builder
+	pre  bool
-	var pre bool
+	list bool
-	var list bool
+}
-	for _, l := range text {
+
-		if _, ok := l.(gemini.LineListItem); ok {
+func (h *HTMLWriter) Handle(line gemini.Line) {
-			if !list {
+	if _, ok := line.(gemini.LineListItem); ok {
-				list = true
+		if !h.list {
-				fmt.Fprint(&b, "<ul>\n")
+			h.list = true
-			}
+			fmt.Fprint(h.out, "<ul>\n")
-		} else if list {
+		}
-			list = false
+	} else if h.list {
-			fmt.Fprint(&b, "</ul>\n")
+		h.list = false
-		}
+		fmt.Fprint(h.out, "</ul>\n")
-		switch l := l.(type) {
+	}
-		case gemini.LineLink:
+	switch line := line.(type) {
-			url := html.EscapeString(l.URL)
+	case gemini.LineLink:
-			name := html.EscapeString(l.Name)
+		url := html.EscapeString(line.URL)
-			if name == "" {
+		name := html.EscapeString(line.Name)
-				name = url
+		if name == "" {
-			}
+			name = url
-			fmt.Fprintf(&b, "<p><a href='%s'>%s</a></p>\n", url, name)
+		}
-		case gemini.LinePreformattingToggle:
+		fmt.Fprintf(h.out, "<p><a href='%s'>%s</a></p>\n", url, name)
-			pre = !pre
+	case gemini.LinePreformattingToggle:
-			if pre {
+		h.pre = !h.pre
-				fmt.Fprint(&b, "<pre>\n")
+		if h.pre {
-			} else {
+			fmt.Fprint(h.out, "<pre>\n")
-				fmt.Fprint(&b, "</pre>\n")
+		} else {
-			}
+			fmt.Fprint(h.out, "</pre>\n")
-		case gemini.LinePreformattedText:
+		}
-			fmt.Fprintf(&b, "%s\n", html.EscapeString(string(l)))
+	case gemini.LinePreformattedText:
-		case gemini.LineHeading1:
+		fmt.Fprintf(h.out, "%s\n", html.EscapeString(string(line)))
-			fmt.Fprintf(&b, "<h1>%s</h1>\n", html.EscapeString(string(l)))
+	case gemini.LineHeading1:
-		case gemini.LineHeading2:
+		fmt.Fprintf(h.out, "<h1>%s</h1>\n", html.EscapeString(string(line)))
-			fmt.Fprintf(&b, "<h2>%s</h2>\n", html.EscapeString(string(l)))
+	case gemini.LineHeading2:
-		case gemini.LineHeading3:
+		fmt.Fprintf(h.out, "<h2>%s</h2>\n", html.EscapeString(string(line)))
-			fmt.Fprintf(&b, "<h3>%s</h3>\n", html.EscapeString(string(l)))
+	case gemini.LineHeading3:
-		case gemini.LineListItem:
+		fmt.Fprintf(h.out, "<h3>%s</h3>\n", html.EscapeString(string(line)))
-			fmt.Fprintf(&b, "<li>%s</li>\n", html.EscapeString(string(l)))
+	case gemini.LineListItem:
-		case gemini.LineQuote:
+		fmt.Fprintf(h.out, "<li>%s</li>\n", html.EscapeString(string(line)))
-			fmt.Fprintf(&b, "<blockquote>%s</blockquote>\n", html.EscapeString(string(l)))
+	case gemini.LineQuote:
-		case gemini.LineText:
+		fmt.Fprintf(h.out, "<blockquote>%s</blockquote>\n", html.EscapeString(string(line)))
-			if l == "" {
+	case gemini.LineText:
-				fmt.Fprint(&b, "<br>\n")
+		if line == "" {
-			} else {
+			fmt.Fprint(h.out, "<br>\n")
-				fmt.Fprintf(&b, "<p>%s</p>\n", html.EscapeString(string(l)))
+		} else {
-			}
+			fmt.Fprintf(h.out, "<p>%s</p>\n", html.EscapeString(string(line)))
-		}
+		}
-	}
+	}
-	if pre {
+}
-		fmt.Fprint(&b, "</pre>\n")
+
-	}
+func (h *HTMLWriter) Finish() {
-	if list {
+	if h.pre {
-		fmt.Fprint(&b, "</ul>\n")
+		fmt.Fprint(h.out, "</pre>\n")
-	}
+	}
-	return b.String()
+	if h.list {
+		fmt.Fprint(h.out, "</ul>\n")
+	}
 }

examples/server.go

@@ -1,38 +1,104 @@
 // +build ignore
 
+// This example illustrates a Gemini server.
+
 package main
 
 import (
-	"crypto/tls"
+	"context"
-	"crypto/x509/pkix"
 	"log"
+	"os"
+	"os/signal"
 	"time"
 
 	"git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini/certificate"
 )
 
 func main() {
-	var server gemini.Server
+	certificates := &certificate.Store{}
-	server.ReadTimeout = 30 * time.Second
+	certificates.Register("localhost")
-	server.WriteTimeout = 1 * time.Minute
+	if err := certificates.Load("/var/lib/gemini/certs"); err != nil {
-	if err := server.Certificates.Load("/var/lib/gemini/certs"); err != nil {
 		log.Fatal(err)
 	}
-	server.CreateCertificate = func(hostname string) (tls.Certificate, error) {
+
-		return gemini.CreateCertificate(gemini.CertificateOptions{
+	mux := &gemini.ServeMux{}
-			Subject: pkix.Name{
+	mux.Handle("/", gemini.FileServer(os.DirFS("/var/www")))
-				CommonName: hostname,
+
-			},
+	server := &gemini.Server{
-			DNSNames: []string{hostname},
+		Handler:        logMiddleware(mux),
-			Duration: 365 * 24 * time.Hour,
+		ReadTimeout:    30 * time.Second,
-		})
+		WriteTimeout:   1 * time.Minute,
+		GetCertificate: certificates.Get,
 	}
 
-	var mux gemini.ServeMux
+	// Listen for interrupt signal
-	mux.Handle("/", gemini.FileServer(gemini.Dir("/var/www")))
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
 
-	server.Register("localhost", &mux)
+	errch := make(chan error)
-	if err := server.ListenAndServe(); err != nil {
+	go func() {
+		ctx := context.Background()
+		errch <- server.ListenAndServe(ctx)
+	}()
+
+	select {
+	case err := <-errch:
 		log.Fatal(err)
+	case <-c:
+		// Shutdown the server
+		log.Println("Shutting down...")
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+		err := server.Shutdown(ctx)
+		if err != nil {
+			log.Fatal(err)
+		}
 	}
 }
+
+func logMiddleware(h gemini.Handler) gemini.Handler {
+	return gemini.HandlerFunc(func(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
+		lw := &logResponseWriter{rw: w}
+		h.ServeGemini(ctx, lw, r)
+		host := r.TLS().ServerName
+		log.Printf("gemini: %s %q %d %d", host, r.URL, lw.status, lw.wrote)
+	})
+}
+
+type logResponseWriter struct {
+	rw          gemini.ResponseWriter
+	status      gemini.Status
+	meta        string
+	mediatype   string
+	wroteHeader bool
+	wrote       int
+}
+
+func (w *logResponseWriter) SetMediaType(mediatype string) {
+	w.mediatype = mediatype
+}
+
+func (w *logResponseWriter) Write(b []byte) (int, error) {
+	if !w.wroteHeader {
+		w.WriteHeader(gemini.StatusSuccess, w.mediatype)
+	}
+	n, err := w.rw.Write(b)
+	w.wrote += n
+	return n, err
+}
+
+func (w *logResponseWriter) WriteHeader(status gemini.Status, meta string) {
+	if w.wroteHeader {
+		return
+	}
+	w.status = status
+	w.meta = meta
+	w.wroteHeader = true
+	w.rw.WriteHeader(status, meta)
+	w.wrote += len(meta) + 5
+}
+
+func (w *logResponseWriter) Flush() error {
+	return nil
+}

examples/stream.go

@@ -0,0 +1,54 @@
+// +build ignore
+
+// This example illustrates a streaming Gemini server.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini/certificate"
+)
+
+func main() {
+	certificates := &certificate.Store{}
+	certificates.Register("localhost")
+	if err := certificates.Load("/var/lib/gemini/certs"); err != nil {
+		log.Fatal(err)
+	}
+
+	mux := &gemini.ServeMux{}
+	mux.HandleFunc("/", stream)
+
+	server := &gemini.Server{
+		Handler:        mux,
+		ReadTimeout:    30 * time.Second,
+		WriteTimeout:   1 * time.Minute,
+		GetCertificate: certificates.Get,
+	}
+
+	ctx := context.Background()
+	if err := server.ListenAndServe(ctx); err != nil {
+		log.Fatal(err)
+	}
+}
+
+// stream writes an infinite stream to w.
+func stream(ctx context.Context, w gemini.ResponseWriter, r *gemini.Request) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+		fmt.Fprintln(w, time.Now().UTC())
+		if err := w.Flush(); err != nil {
+			return
+		}
+		time.Sleep(time.Second)
+	}
+}

fs.go

@@ -1,105 +1,213 @@
+// +build go1.16
+
 package gemini
 
 import (
+	"context"
+	"errors"
+	"fmt"
 	"io"
+	"io/fs"
 	"mime"
-	"os"
+	"net/url"
 	"path"
+	"sort"
+	"strings"
 )
 
-func init() {
+// FileServer returns a handler that serves Gemini requests with the contents
-	// Add Gemini mime types
+// of the provided file system.
-	mime.AddExtensionType(".gmi", "text/gemini")
+//
-	mime.AddExtensionType(".gemini", "text/gemini")
+// To use the operating system's file system implementation, use os.DirFS:
+//
+//     gemini.FileServer(os.DirFS("/tmp"))
+func FileServer(fsys fs.FS) Handler {
+	return fileServer{fsys}
 }
 
-// FileServer takes a filesystem and returns a Responder which uses that filesystem.
+type fileServer struct {
-// The returned Responder sanitizes paths before handling them.
+	fs.FS
-func FileServer(fsys FS) Responder {
-	return fsHandler{fsys}
 }
 
-type fsHandler struct {
+func (fs fileServer) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
-	FS
+	serveFile(w, r, fs, path.Clean(r.URL.Path), true)
 }
 
-func (fsh fsHandler) Respond(w *ResponseWriter, r *Request) {
+// ServeContent replies to the request using the content in the
-	p := path.Clean(r.URL.Path)
+// provided Reader. The main benefit of ServeContent over io.Copy
-	f, err := fsh.Open(p)
+// is that it sets the MIME type of the response.
-	if err != nil {
+//
-		w.WriteStatus(StatusNotFound)
+// ServeContent tries to deduce the type from name's file extension.
-		return
+// The name is otherwise unused; it is never sent in the response.
-	}
+func ServeContent(w ResponseWriter, r *Request, name string, content io.Reader) {
-	// Detect mimetype
+	serveContent(w, name, content)
-	ext := path.Ext(p)
+}
+
+func serveContent(w ResponseWriter, name string, content io.Reader) {
+	// Detect mimetype from file extension
+	ext := path.Ext(name)
 	mimetype := mime.TypeByExtension(ext)
 	w.SetMediaType(mimetype)
-	// Copy file to response writer
+	io.Copy(w, content)
-	io.Copy(w, f)
-}
-
-// TODO: replace with io/fs.FS when available
-type FS interface {
-	Open(name string) (File, error)
-}
-
-// TODO: replace with io/fs.File when available
-type File interface {
-	Stat() (os.FileInfo, error)
-	Read([]byte) (int, error)
-	Close() error
-}
-
-// Dir implements FS using the native filesystem restricted to a specific directory.
-type Dir string
-
-// Open tries to open the file with the given name.
-// If the file is a directory, it tries to open the index file in that directory.
-func (d Dir) Open(name string) (File, error) {
-	p := path.Join(string(d), name)
-	return openFile(p)
 }
 
 // ServeFile responds to the request with the contents of the named file
 // or directory.
-// TODO: Use io/fs.FS when available.
+//
-func ServeFile(w *ResponseWriter, fs FS, name string) {
+// If the provided file or directory name is a relative path, it is interpreted
-	f, err := fs.Open(name)
+// relative to the current directory and may ascend to parent directories. If
-	if err != nil {
+// the provided name is constructed from user input, it should be sanitized
-		w.WriteStatus(StatusNotFound)
+// before calling ServeFile.
+//
+// As a precaution, ServeFile will reject requests where r.URL.Path contains a
+// ".." path element; this protects against callers who might unsafely use
+// path.Join on r.URL.Path without sanitizing it and then use that
+// path.Join result as the name argument.
+//
+// As another special case, ServeFile redirects any request where r.URL.Path
+// ends in "/index.gmi" to the same path, without the final "index.gmi". To
+// avoid such redirects either modify the path or use ServeContent.
+//
+// Outside of those two special cases, ServeFile does not use r.URL.Path for
+// selecting the file or directory to serve; only the file or directory
+// provided in the name argument is used.
+func ServeFile(w ResponseWriter, r *Request, fsys fs.FS, name string) {
+	if containsDotDot(r.URL.Path) {
+		// Too many programs use r.URL.Path to construct the argument to
+		// serveFile. Reject the request under the assumption that happened
+		// here and ".." may not be wanted.
+		// Note that name might not contain "..", for example if code (still
+		// incorrectly) used path.Join(myDir, r.URL.Path).
+		w.WriteHeader(StatusBadRequest, "invalid URL path")
 		return
 	}
-	// Detect mimetype
+	serveFile(w, r, fsys, name, false)
-	ext := path.Ext(name)
-	mimetype := mime.TypeByExtension(ext)
-	w.SetMediaType(mimetype)
-	// Copy file to response writer
-	io.Copy(w, f)
 }
 
-func openFile(p string) (File, error) {
+func containsDotDot(v string) bool {
-	f, err := os.OpenFile(p, os.O_RDONLY, 0644)
+	if !strings.Contains(v, "..") {
-	if err != nil {
+		return false
-		return nil, err
 	}
-
+	for _, ent := range strings.FieldsFunc(v, isSlashRune) {
-	if stat, err := f.Stat(); err == nil {
+		if ent == ".." {
-		if stat.IsDir() {
+			return true
-			f, err := os.Open(path.Join(p, "index.gmi"))
-			if err != nil {
-				return nil, err
-			}
-			stat, err := f.Stat()
-			if err != nil {
-				return nil, err
-			}
-			if stat.Mode().IsRegular() {
-				return f, nil
-			}
-			return nil, os.ErrNotExist
-		} else if !stat.Mode().IsRegular() {
-			return nil, os.ErrNotExist
 		}
 	}
-	return f, nil
+	return false
+}
+
+func isSlashRune(r rune) bool { return r == '/' || r == '\\' }
+
+func serveFile(w ResponseWriter, r *Request, fsys fs.FS, name string, redirect bool) {
+	const indexPage = "/index.gmi"
+
+	// Redirect .../index.gmi to .../
+	if strings.HasSuffix(r.URL.Path, indexPage) {
+		w.WriteHeader(StatusPermanentRedirect, "./")
+		return
+	}
+
+	if name == "/" {
+		name = "."
+	} else {
+		name = strings.Trim(name, "/")
+	}
+
+	f, err := fsys.Open(name)
+	if err != nil {
+		w.WriteHeader(toGeminiError(err))
+		return
+	}
+	defer f.Close()
+
+	stat, err := f.Stat()
+	if err != nil {
+		w.WriteHeader(toGeminiError(err))
+		return
+	}
+
+	// Redirect to canonical path
+	if redirect {
+		url := r.URL.Path
+		if stat.IsDir() {
+			// Add trailing slash
+			if url[len(url)-1] != '/' {
+				w.WriteHeader(StatusPermanentRedirect, path.Base(url)+"/")
+				return
+			}
+		} else {
+			// Remove trailing slash
+			if url[len(url)-1] == '/' {
+				w.WriteHeader(StatusPermanentRedirect, "../"+path.Base(url))
+				return
+			}
+		}
+	}
+
+	if stat.IsDir() {
+		// Redirect if the directory name doesn't end in a slash
+		url := r.URL.Path
+		if url[len(url)-1] != '/' {
+			w.WriteHeader(StatusRedirect, path.Base(url)+"/")
+			return
+		}
+
+		// Use contents of index.gmi if present
+		index, err := fsys.Open(path.Join(name, indexPage))
+		if err == nil {
+			defer index.Close()
+			istat, err := index.Stat()
+			if err == nil {
+				f = index
+				stat = istat
+			}
+		}
+	}
+
+	if stat.IsDir() {
+		// Failed to find index file
+		dirList(w, f)
+		return
+	}
+
+	serveContent(w, name, f)
+}
+
+func dirList(w ResponseWriter, f fs.File) {
+	var entries []fs.DirEntry
+	var err error
+	d, ok := f.(fs.ReadDirFile)
+	if ok {
+		entries, err = d.ReadDir(-1)
+	}
+	if !ok || err != nil {
+		w.WriteHeader(StatusTemporaryFailure, "Error reading directory")
+		return
+	}
+
+	sort.Slice(entries, func(i, j int) bool {
+		return entries[i].Name() < entries[j].Name()
+	})
+
+	for _, entry := range entries {
+		name := entry.Name()
+		if entry.IsDir() {
+			name += "/"
+		}
+		link := LineLink{
+			Name: name,
+			URL:  (&url.URL{Path: name}).EscapedPath(),
+		}
+		fmt.Fprintln(w, link.String())
+	}
+}
+
+func toGeminiError(err error) (status Status, meta string) {
+	if errors.Is(err, fs.ErrNotExist) {
+		return StatusNotFound, "Not found"
+	}
+	if errors.Is(err, fs.ErrPermission) {
+		return StatusNotFound, "Forbidden"
+	}
+	return StatusTemporaryFailure, "Internal server error"
 }

gemini.go

@@ -1,63 +1,26 @@
-/*
-Package gemini implements the Gemini protocol.
-
-Client is a Gemini client.
-
-	client := &gemini.Client{}
-	resp, err := client.Get("gemini://example.com")
-	if err != nil {
-		// handle error
-	}
-	if resp.Status.Class() == gemini.StatusClassSucess {
-		defer resp.Body.Close()
-		// ...
-	}
-	// ...
-
-Server is a Gemini server.
-
-	server := &gemini.Server{
-		ReadTimeout:    10 * time.Second,
-		WriteTimeout:   10 * time.Second,
-	}
-
-Servers should be configured with certificates:
-
-	err := server.Certificates.Load("/var/lib/gemini/certs")
-	if err != nil {
-		// handle error
-	}
-
-Servers can accept requests for multiple hosts and schemes:
-
-	server.RegisterFunc("example.com", func(w *gemini.ResponseWriter, r *gemini.Request) {
-		fmt.Fprint(w, "Welcome to example.com")
-	})
-	server.RegisterFunc("example.org", func(w *gemini.ResponseWriter, r *gemini.Request) {
-		fmt.Fprint(w, "Welcome to example.org")
-	})
-	server.RegisterFunc("http://example.net", func(w *gemini.ResponseWriter, r *gemini.Request) {
-		fmt.Fprint(w, "Proxied content from http://example.net")
-	})
-
-To start the server, call ListenAndServe:
-
-	err := server.ListenAndServe()
-	if err != nil {
-		// handle error
-	}
-*/
 package gemini
 
 import (
 	"errors"
+	"mime"
 )
 
+func init() {
+	// Add Gemini mime types
+	mime.AddExtensionType(".gmi", "text/gemini")
+	mime.AddExtensionType(".gemini", "text/gemini")
+}
+
 var crlf = []byte("\r\n")
 
 // Errors.
 var (
-	ErrInvalidURL      = errors.New("gemini: invalid URL")
+	ErrInvalidRequest  = errors.New("gemini: invalid request")
 	ErrInvalidResponse = errors.New("gemini: invalid response")
-	ErrBodyNotAllowed  = errors.New("gemini: response body not allowed")
+
+	ErrCertificateExpired = errors.New("gemini: certificate expired")
+
+	// ErrBodyNotAllowed is returned by ResponseWriter.Write calls
+	// when the response status code does not permit a body.
+	ErrBodyNotAllowed = errors.New("gemini: response status code does not allow body")
 )

go.mod

@@ -1,3 +1,5 @@
 module git.sr.ht/~adnano/go-gemini
 
 go 1.15
+
+require golang.org/x/net v0.0.0-20210119194325-5f4716e94777

go.sum

@@ -0,0 +1,7 @@
+golang.org/x/net v0.0.0-20210119194325-5f4716e94777 h1:003p0dJM77cxMSyCPFphvZf/Y5/NXf5fzg6ufd1/Oew=
+golang.org/x/net v0.0.0-20210119194325-5f4716e94777/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.3 h1:cokOdA+Jmi5PJGXLlLllQSgYigAEfHXJAERHVMaCc2k=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

handler.go

@@ -0,0 +1,155 @@
+package gemini
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// A Handler responds to a Gemini request.
+//
+// ServeGemini should write the response header and data to the ResponseWriter
+// and then return. Returning signals that the request is finished; it is not
+// valid to use the ResponseWriter after or concurrently with the completion
+// of the ServeGemini call.
+//
+// The provided context is canceled when the client's connection is closed
+// or the ServeGemini method returns.
+//
+// Handlers should not modify the provided Request.
+type Handler interface {
+	ServeGemini(context.Context, ResponseWriter, *Request)
+}
+
+// The HandlerFunc type is an adapter to allow the use of ordinary functions
+// as Gemini handlers. If f is a function with the appropriate signature,
+// HandlerFunc(f) is a Handler that calls f.
+type HandlerFunc func(context.Context, ResponseWriter, *Request)
+
+// ServeGemini calls f(ctx, w, r).
+func (f HandlerFunc) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
+	f(ctx, w, r)
+}
+
+// StatusHandler returns a request handler that responds to each request
+// with the provided status code and meta.
+func StatusHandler(status Status, meta string) Handler {
+	return HandlerFunc(func(ctx context.Context, w ResponseWriter, r *Request) {
+		w.WriteHeader(status, meta)
+	})
+}
+
+// NotFoundHandler returns a simple request handler that replies to each
+// request with a “51 Not found” reply.
+func NotFoundHandler() Handler {
+	return StatusHandler(StatusNotFound, "Not found")
+}
+
+// StripPrefix returns a handler that serves Gemini requests by removing the
+// given prefix from the request URL's Path (and RawPath if set) and invoking
+// the handler h. StripPrefix handles a request for a path that doesn't begin
+// with prefix by replying with a Gemini 51 not found error. The prefix must
+// match exactly: if the prefix in the request contains escaped characters the
+// reply is also a Gemini 51 not found error.
+func StripPrefix(prefix string, h Handler) Handler {
+	if prefix == "" {
+		return h
+	}
+	return HandlerFunc(func(ctx context.Context, w ResponseWriter, r *Request) {
+		p := strings.TrimPrefix(r.URL.Path, prefix)
+		rp := strings.TrimPrefix(r.URL.RawPath, prefix)
+		if len(p) < len(r.URL.Path) && (r.URL.RawPath == "" || len(rp) < len(r.URL.RawPath)) {
+			r2 := new(Request)
+			*r2 = *r
+			r2.URL = new(url.URL)
+			*r2.URL = *r.URL
+			r2.URL.Path = p
+			r2.URL.RawPath = rp
+			h.ServeGemini(ctx, w, r2)
+		} else {
+			w.WriteHeader(StatusNotFound, "Not found")
+		}
+	})
+}
+
+// TimeoutHandler returns a Handler that runs h with the given time limit.
+//
+// The new Handler calls h.ServeGemini to handle each request, but
+// if a call runs for longer than its time limit, the handler responds with a
+// 40 Temporary Failure error.  After such a timeout, writes by h to
+// its ResponseWriter will return context.DeadlineExceeded.
+func TimeoutHandler(h Handler, dt time.Duration) Handler {
+	return &timeoutHandler{
+		h:  h,
+		dt: dt,
+	}
+}
+
+type timeoutHandler struct {
+	h  Handler
+	dt time.Duration
+}
+
+func (t *timeoutHandler) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
+	ctx, cancel := context.WithTimeout(ctx, t.dt)
+	defer cancel()
+
+	buf := &bytes.Buffer{}
+	tw := &timeoutWriter{
+		wr: &contextWriter{
+			ctx:    ctx,
+			cancel: cancel,
+			done:   ctx.Done(),
+			wc:     nopCloser{buf},
+		},
+	}
+
+	done := make(chan struct{})
+	go func() {
+		t.h.ServeGemini(ctx, tw, r)
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		w.WriteHeader(tw.status, tw.meta)
+		w.Write(buf.Bytes())
+	case <-ctx.Done():
+		w.WriteHeader(StatusTemporaryFailure, "Timeout")
+	}
+}
+
+type timeoutWriter struct {
+	wr          io.Writer
+	status      Status
+	meta        string
+	mediatype   string
+	wroteHeader bool
+}
+
+func (w *timeoutWriter) SetMediaType(mediatype string) {
+	w.mediatype = mediatype
+}
+
+func (w *timeoutWriter) Write(b []byte) (int, error) {
+	if !w.wroteHeader {
+		w.WriteHeader(StatusSuccess, w.mediatype)
+	}
+	return w.wr.Write(b)
+}
+
+func (w *timeoutWriter) WriteHeader(status Status, meta string) {
+	if w.wroteHeader {
+		return
+	}
+	w.status = status
+	w.meta = meta
+	w.wroteHeader = true
+}
+
+func (w *timeoutWriter) Flush() error {
+	return nil
+}

io.go

@@ -0,0 +1,104 @@
+package gemini
+
+import (
+	"bufio"
+	"context"
+	"io"
+)
+
+type contextReader struct {
+	ctx    context.Context
+	done   <-chan struct{}
+	cancel func()
+	rc     io.ReadCloser
+}
+
+func (r *contextReader) Read(p []byte) (int, error) {
+	select {
+	case <-r.done:
+		r.rc.Close()
+		return 0, r.ctx.Err()
+	default:
+	}
+	n, err := r.rc.Read(p)
+	if err != nil {
+		r.cancel()
+	}
+	return n, err
+}
+
+func (r *contextReader) Close() error {
+	r.cancel()
+	return r.rc.Close()
+}
+
+type contextWriter struct {
+	ctx    context.Context
+	done   <-chan struct{}
+	cancel func()
+	wc     io.WriteCloser
+}
+
+func (w *contextWriter) Write(b []byte) (int, error) {
+	select {
+	case <-w.done:
+		w.wc.Close()
+		return 0, w.ctx.Err()
+	default:
+	}
+	n, err := w.wc.Write(b)
+	if err != nil {
+		w.cancel()
+	}
+	return n, err
+}
+
+func (w *contextWriter) Close() error {
+	w.cancel()
+	return w.wc.Close()
+}
+
+type nopCloser struct {
+	io.Writer
+}
+
+func (nopCloser) Close() error {
+	return nil
+}
+
+type nopReadCloser struct{}
+
+func (nopReadCloser) Read(p []byte) (int, error) {
+	return 0, io.EOF
+}
+
+func (nopReadCloser) Close() error {
+	return nil
+}
+
+type bufReadCloser struct {
+	br *bufio.Reader // used until empty
+	io.ReadCloser
+}
+
+func newBufReadCloser(br *bufio.Reader, rc io.ReadCloser) io.ReadCloser {
+	body := &bufReadCloser{ReadCloser: rc}
+	if br.Buffered() != 0 {
+		body.br = br
+	}
+	return body
+}
+
+func (b *bufReadCloser) Read(p []byte) (n int, err error) {
+	if b.br != nil {
+		if n := b.br.Buffered(); len(p) > n {
+			p = p[:n]
+		}
+		n, err = b.br.Read(p)
+		if b.br.Buffered() == 0 {
+			b.br = nil
+		}
+		return n, err
+	}
+	return b.ReadCloser.Read(p)
+}

mux.go

@@ -1,6 +1,8 @@
 package gemini
 
 import (
+	"context"
+	"net"
 	"net/url"
 	"path"
 	"sort"
@@ -8,12 +10,6 @@ import (
 	"sync"
 )
 
-// The following code is modified from the net/http package.
-
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
 // ServeMux is a Gemini request multiplexer.
 // It matches the URL of each incoming request against a list of registered
 // patterns and calls the handler for the pattern that
@@ -32,6 +28,32 @@ import (
 // the pattern "/" matches all paths not matched by other registered
 // patterns, not just the URL with Path == "/".
 //
+// Patterns may also contain schemes and hostnames.
+// Wildcard patterns can be used to match multiple hostnames (e.g. "*.example.com").
+//
+// The following are examples of valid patterns, along with the scheme,
+// hostname, and path that they match.
+//
+//     Pattern                      │ Scheme │ Hostname │ Path
+//     ─────────────────────────────┼────────┼──────────┼─────────────
+//     /file                        │ gemini │ *        │ /file
+//     /directory/                  │ gemini │ *        │ /directory/*
+//     hostname/file                │ gemini │ hostname │ /file
+//     hostname/directory/          │ gemini │ hostname │ /directory/*
+//     scheme://hostname/file       │ scheme │ hostname │ /file
+//     scheme://hostname/directory/ │ scheme │ hostname │ /directory/*
+//     //hostname/file              │ *      │ hostname │ /file
+//     //hostname/directory/        │ *      │ hostname │ /directory/*
+//     scheme:///file               │ scheme │ *        │ /file
+//     scheme:///directory/         │ scheme │ *        │ /directory/*
+//     ///file                      │ *      │ *        │ /file
+//     ///directory/                │ *      │ *        │ /directory/*
+//
+// A pattern without a hostname will match any hostname.
+// If a pattern begins with "//", it will match any scheme.
+// Otherwise, a pattern with no scheme is treated as though it has a
+// scheme of "gemini".
+//
 // If a subtree has been registered and a request is received naming the
 // subtree root without its trailing slash, ServeMux redirects that
 // request to the subtree root (adding the trailing slash). This behavior can
@@ -45,13 +67,19 @@ import (
 // to an equivalent, cleaner URL.
 type ServeMux struct {
 	mu sync.RWMutex
-	m  map[string]muxEntry
+	m  map[muxKey]Handler
-	es []muxEntry // slice of entries sorted from longest to shortest.
+	es []muxEntry // slice of entries sorted from longest to shortest
+}
+
+type muxKey struct {
+	scheme string
+	host   string
+	path   string
 }
 
 type muxEntry struct {
-	r       Responder
+	handler Handler
-	pattern string
+	key     muxKey
 }
 
 // cleanPath returns the canonical path for p, eliminating . and .. elements.
@@ -78,18 +106,25 @@ func cleanPath(p string) string {
 
 // Find a handler on a handler map given a path string.
 // Most-specific (longest) pattern wins.
-func (mux *ServeMux) match(path string) Responder {
+func (mux *ServeMux) match(key muxKey) Handler {
 	// Check for exact match first.
-	v, ok := mux.m[path]
+	if r, ok := mux.m[key]; ok {
-	if ok {
+		return r
-		return v.r
+	} else if r, ok := mux.m[muxKey{"", key.host, key.path}]; ok {
+		return r
+	} else if r, ok := mux.m[muxKey{key.scheme, "", key.path}]; ok {
+		return r
+	} else if r, ok := mux.m[muxKey{"", "", key.path}]; ok {
+		return r
 	}
 
 	// Check for longest valid match.  mux.es contains all patterns
 	// that end in / sorted from longest to shortest.
 	for _, e := range mux.es {
-		if strings.HasPrefix(path, e.pattern) {
+		if (e.key.scheme == "" || key.scheme == e.key.scheme) &&
-			return e.r
+			(e.key.host == "" || key.host == e.key.host) &&
+			strings.HasPrefix(key.path, e.key.path) {
+			return e.handler
 		}
 	}
 	return nil
@@ -99,89 +134,144 @@ func (mux *ServeMux) match(path string) Responder {
 // This occurs when a handler for path + "/" was already registered, but
 // not for path itself. If the path needs appending to, it creates a new
 // URL, setting the path to u.Path + "/" and returning true to indicate so.
-func (mux *ServeMux) redirectToPathSlash(path string, u *url.URL) (*url.URL, bool) {
+func (mux *ServeMux) redirectToPathSlash(key muxKey, u *url.URL) (*url.URL, bool) {
 	mux.mu.RLock()
-	shouldRedirect := mux.shouldRedirectRLocked(path)
+	shouldRedirect := mux.shouldRedirectRLocked(key)
 	mux.mu.RUnlock()
 	if !shouldRedirect {
 		return u, false
 	}
-	path = path + "/"
+	return u.ResolveReference(&url.URL{Path: key.path + "/"}), true
-	u = &url.URL{Path: path, RawQuery: u.RawQuery}
-	return u, true
 }
 
 // shouldRedirectRLocked reports whether the given path and host should be redirected to
 // path+"/". This should happen if a handler is registered for path+"/" but
 // not path -- see comments at ServeMux.
-func (mux *ServeMux) shouldRedirectRLocked(path string) bool {
+func (mux *ServeMux) shouldRedirectRLocked(key muxKey) bool {
-	if _, exist := mux.m[path]; exist {
+	if _, exist := mux.m[key]; exist {
 		return false
 	}
 
-	n := len(path)
+	n := len(key.path)
 	if n == 0 {
 		return false
 	}
-	if _, exist := mux.m[path+"/"]; exist {
+	if _, exist := mux.m[muxKey{key.scheme, key.host, key.path + "/"}]; exist {
-		return path[n-1] != '/'
+		return key.path[n-1] != '/'
 	}
-
 	return false
 }
 
-// Respond dispatches the request to the responder whose
+func getWildcard(hostname string) (string, bool) {
-// pattern most closely matches the request URL.
+	if net.ParseIP(hostname) == nil {
-func (mux *ServeMux) Respond(w *ResponseWriter, r *Request) {
+		split := strings.SplitN(hostname, ".", 2)
+		if len(split) == 2 {
+			return "*." + split[1], true
+		}
+	}
+	return "", false
+}
+
+// Handler returns the handler to use for the given request, consulting
+// r.URL.Scheme, r.URL.Host, and r.URL.Path. It always returns a non-nil handler. If
+// the path is not in its canonical form, the handler will be an
+// internally-generated handler that redirects to the canonical path. If the
+// host contains a port, it is ignored when matching handlers.
+func (mux *ServeMux) Handler(r *Request) Handler {
+	scheme := r.URL.Scheme
+	host := r.URL.Hostname()
 	path := cleanPath(r.URL.Path)
 
 	// If the given path is /tree and its handler is not registered,
 	// redirect for /tree/.
-	if u, ok := mux.redirectToPathSlash(path, r.URL); ok {
+	if u, ok := mux.redirectToPathSlash(muxKey{scheme, host, path}, r.URL); ok {
-		w.WriteHeader(StatusRedirect, u.String())
+		return StatusHandler(StatusPermanentRedirect, u.String())
-		return
 	}
 
 	if path != r.URL.Path {
 		u := *r.URL
 		u.Path = path
-		w.WriteHeader(StatusRedirect, u.String())
+		return StatusHandler(StatusPermanentRedirect, u.String())
-		return
 	}
 
 	mux.mu.RLock()
 	defer mux.mu.RUnlock()
 
-	resp := mux.match(path)
+	h := mux.match(muxKey{scheme, host, path})
-	if resp == nil {
+	if h == nil {
-		w.WriteStatus(StatusNotFound)
+		// Try wildcard
-		return
+		if wildcard, ok := getWildcard(host); ok {
+			h = mux.match(muxKey{scheme, wildcard, path})
+		}
 	}
-	resp.Respond(w, r)
+	if h == nil {
+		h = NotFoundHandler()
+	}
+	return h
 }
 
-// Handle registers the responder for the given pattern.
+// ServeGemini dispatches the request to the handler whose
-// If a responder already exists for pattern, Handle panics.
+// pattern most closely matches the request URL.
-func (mux *ServeMux) Handle(pattern string, responder Responder) {
+func (mux *ServeMux) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
-	mux.mu.Lock()
+	h := mux.Handler(r)
-	defer mux.mu.Unlock()
+	h.ServeGemini(ctx, w, r)
+}
 
+// Handle registers the handler for the given pattern.
+// If a handler already exists for pattern, Handle panics.
+func (mux *ServeMux) Handle(pattern string, handler Handler) {
 	if pattern == "" {
 		panic("gemini: invalid pattern")
 	}
-	if responder == nil {
+	if handler == nil {
-		panic("gemini: nil responder")
+		panic("gemini: nil handler")
 	}
-	if _, exist := mux.m[pattern]; exist {
+
+	mux.mu.Lock()
+	defer mux.mu.Unlock()
+
+	var key muxKey
+	if strings.HasPrefix(pattern, "//") {
+		// match any scheme
+		key.scheme = ""
+		pattern = pattern[2:]
+	} else {
+		// extract scheme
+		cut := strings.Index(pattern, "://")
+		if cut == -1 {
+			// default scheme of gemini
+			key.scheme = "gemini"
+		} else {
+			key.scheme = pattern[:cut]
+			pattern = pattern[cut+3:]
+		}
+	}
+
+	// extract hostname and path
+	cut := strings.Index(pattern, "/")
+	if cut == -1 {
+		key.host = pattern
+		key.path = "/"
+	} else {
+		key.host = pattern[:cut]
+		key.path = pattern[cut:]
+	}
+
+	// strip port from hostname
+	if hostname, _, err := net.SplitHostPort(key.host); err == nil {
+		key.host = hostname
+	}
+
+	if _, exist := mux.m[key]; exist {
 		panic("gemini: multiple registrations for " + pattern)
 	}
 
 	if mux.m == nil {
-		mux.m = make(map[string]muxEntry)
+		mux.m = make(map[muxKey]Handler)
 	}
-	e := muxEntry{responder, pattern}
+	mux.m[key] = handler
-	mux.m[pattern] = e
+	e := muxEntry{handler, key}
-	if pattern[len(pattern)-1] == '/' {
+	if key.path[len(key.path)-1] == '/' {
 		mux.es = appendSorted(mux.es, e)
 	}
 }
@@ -189,7 +279,9 @@ func (mux *ServeMux) Handle(pattern string, responder Responder) {
 func appendSorted(es []muxEntry, e muxEntry) []muxEntry {
 	n := len(es)
 	i := sort.Search(n, func(i int) bool {
-		return len(es[i].pattern) < len(e.pattern)
+		return len(es[i].key.scheme) < len(e.key.scheme) ||
+			len(es[i].key.host) < len(es[i].key.host) ||
+			len(es[i].key.path) < len(e.key.path)
 	})
 	if i == n {
 		return append(es, e)
@@ -201,10 +293,7 @@ func appendSorted(es []muxEntry, e muxEntry) []muxEntry {
 	return es
 }
 
-// HandleFunc registers the responder function for the given pattern.
+// HandleFunc registers the handler function for the given pattern.
-func (mux *ServeMux) HandleFunc(pattern string, responder func(*ResponseWriter, *Request)) {
+func (mux *ServeMux) HandleFunc(pattern string, handler HandlerFunc) {
-	if responder == nil {
+	mux.Handle(pattern, handler)
-		panic("gemini: nil responder")
-	}
-	mux.Handle(pattern, ResponderFunc(responder))
 }

mux_test.go

@@ -0,0 +1,315 @@
+package gemini
+
+import (
+	"context"
+	"net/url"
+	"testing"
+)
+
+type nopHandler struct{}
+
+func (*nopHandler) ServeGemini(context.Context, ResponseWriter, *Request) {}
+
+func TestServeMuxMatch(t *testing.T) {
+	type Match struct {
+		URL string
+		Ok  bool
+	}
+
+	tests := []struct {
+		Pattern string
+		Matches []Match
+	}{
+		{
+			// scheme: gemini, hostname: *, path: /*
+			Pattern: "/",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", true},
+				{"gemini://example.com/path.gmi", true},
+				{"gemini://example.com/path/", true},
+				{"gemini://example.org/path", true},
+				{"http://example.com/path", false},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: gemini, hostname: *, path: /path
+			Pattern: "/path",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", false},
+				{"gemini://example.com/path.gmi", false},
+				{"gemini://example.com/path/", false},
+				{"gemini://example.org/path", true},
+				{"http://example.com/path", false},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: gemini, hostname: *, path: /subtree/*
+			Pattern: "/subtree/",
+			Matches: []Match{
+				{"gemini://example.com/subtree/", true},
+				{"gemini://example.com/subtree/nested/", true},
+				{"gemini://example.com/subtree/nested/file", true},
+				{"gemini://example.org/subtree/", true},
+				{"gemini://example.org/subtree/nested/", true},
+				{"gemini://example.org/subtree/nested/file", true},
+				{"gemini://example.com/subtree", false},
+				{"gemini://www.example.com/subtree/", true},
+				{"http://example.com/subtree/", false},
+			},
+		},
+		{
+			// scheme: gemini, hostname: example.com, path: /*
+			Pattern: "example.com",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", true},
+				{"gemini://example.com/path.gmi", true},
+				{"gemini://example.com/path/", true},
+				{"gemini://example.org/path", false},
+				{"http://example.com/path", false},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: gemini, hostname: example.com, path: /path
+			Pattern: "example.com/path",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", false},
+				{"gemini://example.com/path.gmi", false},
+				{"gemini://example.com/path/", false},
+				{"gemini://example.org/path", false},
+				{"http://example.com/path", false},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: gemini, hostname: example.com, path: /subtree/*
+			Pattern: "example.com/subtree/",
+			Matches: []Match{
+				{"gemini://example.com/subtree/", true},
+				{"gemini://example.com/subtree/nested/", true},
+				{"gemini://example.com/subtree/nested/file", true},
+				{"gemini://example.org/subtree/", false},
+				{"gemini://example.org/subtree/nested/", false},
+				{"gemini://example.org/subtree/nested/file", false},
+				{"gemini://example.com/subtree", false},
+				{"gemini://www.example.com/subtree/", false},
+				{"http://example.com/subtree/", false},
+			},
+		},
+		{
+			// scheme: http, hostname: example.com, path: /*
+			Pattern: "http://example.com",
+			Matches: []Match{
+				{"http://example.com/path", true},
+				{"http://example.com/", true},
+				{"http://example.com/path.gmi", true},
+				{"http://example.com/path/", true},
+				{"http://example.org/path", false},
+				{"gemini://example.com/path", false},
+				{"gemini://example.org/path", false},
+			},
+		},
+		{
+			// scheme: http, hostname: example.com, path: /path
+			Pattern: "http://example.com/path",
+			Matches: []Match{
+				{"http://example.com/path", true},
+				{"http://example.com/", false},
+				{"http://example.com/path.gmi", false},
+				{"http://example.com/path/", false},
+				{"http://example.org/path", false},
+				{"gemini://example.com/path", false},
+				{"gemini://example.org/path", false},
+			},
+		},
+		{
+			// scheme: http, hostname: example.com, path: /subtree/*
+			Pattern: "http://example.com/subtree/",
+			Matches: []Match{
+				{"http://example.com/subtree/", true},
+				{"http://example.com/subtree/nested/", true},
+				{"http://example.com/subtree/nested/file", true},
+				{"http://example.org/subtree/", false},
+				{"http://example.org/subtree/nested/", false},
+				{"http://example.org/subtree/nested/file", false},
+				{"http://example.com/subtree", false},
+				{"http://www.example.com/subtree/", false},
+				{"gemini://example.com/subtree/", false},
+			},
+		},
+		{
+			// scheme: *, hostname: example.com, path: /*
+			Pattern: "//example.com",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", true},
+				{"gemini://example.com/path.gmi", true},
+				{"gemini://example.com/path/", true},
+				{"gemini://example.org/path", false},
+				{"http://example.com/path", true},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: *, hostname: example.com, path: /path
+			Pattern: "//example.com/path",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", false},
+				{"gemini://example.com/path.gmi", false},
+				{"gemini://example.com/path/", false},
+				{"gemini://example.org/path", false},
+				{"http://example.com/path", true},
+				{"http://example.org/path", false},
+			},
+		},
+		{
+			// scheme: *, hostname: example.com, path: /subtree/*
+			Pattern: "//example.com/subtree/",
+			Matches: []Match{
+				{"gemini://example.com/subtree/", true},
+				{"gemini://example.com/subtree/nested/", true},
+				{"gemini://example.com/subtree/nested/file", true},
+				{"gemini://example.org/subtree/", false},
+				{"gemini://example.org/subtree/nested/", false},
+				{"gemini://example.org/subtree/nested/file", false},
+				{"gemini://example.com/subtree", false},
+				{"gemini://www.example.com/subtree/", false},
+				{"http://example.com/subtree/", true},
+			},
+		},
+		{
+			// scheme: http, hostname: *, path: /*
+			Pattern: "http://",
+			Matches: []Match{
+				{"http://example.com/path", true},
+				{"http://example.com/", true},
+				{"http://example.com/path.gmi", true},
+				{"http://example.com/path/", true},
+				{"http://example.org/path", true},
+				{"gemini://example.com/path", false},
+				{"gemini://example.org/path", false},
+			},
+		},
+		{
+			// scheme: http, hostname: *, path: /path
+			Pattern: "http:///path",
+			Matches: []Match{
+				{"http://example.com/path", true},
+				{"http://example.com/", false},
+				{"http://example.com/path.gmi", false},
+				{"http://example.com/path/", false},
+				{"http://example.org/path", true},
+				{"gemini://example.com/path", false},
+				{"gemini://example.org/path", false},
+			},
+		},
+		{
+			// scheme: http, hostname: *, path: /subtree/*
+			Pattern: "http:///subtree/",
+			Matches: []Match{
+				{"http://example.com/subtree/", true},
+				{"http://example.com/subtree/nested/", true},
+				{"http://example.com/subtree/nested/file", true},
+				{"http://example.org/subtree/", true},
+				{"http://example.org/subtree/nested/", true},
+				{"http://example.org/subtree/nested/file", true},
+				{"http://example.com/subtree", false},
+				{"http://www.example.com/subtree/", true},
+				{"gemini://example.com/subtree/", false},
+			},
+		},
+		{
+			// scheme: *, hostname: *, path: /*
+			Pattern: "//",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", true},
+				{"gemini://example.com/path.gmi", true},
+				{"gemini://example.com/path/", true},
+				{"gemini://example.org/path", true},
+				{"http://example.com/path", true},
+				{"http://example.org/path", true},
+			},
+		},
+		{
+			// scheme: *, hostname: *, path: /path
+			Pattern: "///path",
+			Matches: []Match{
+				{"gemini://example.com/path", true},
+				{"gemini://example.com/", false},
+				{"gemini://example.com/path.gmi", false},
+				{"gemini://example.com/path/", false},
+				{"gemini://example.org/path", true},
+				{"http://example.com/path", true},
+				{"http://example.org/path", true},
+			},
+		},
+		{
+			// scheme: *, hostname: *, path: /subtree/*
+			Pattern: "///subtree/",
+			Matches: []Match{
+				{"gemini://example.com/subtree/", true},
+				{"gemini://example.com/subtree/nested/", true},
+				{"gemini://example.com/subtree/nested/file", true},
+				{"gemini://example.org/subtree/", true},
+				{"gemini://example.org/subtree/nested/", true},
+				{"gemini://example.org/subtree/nested/file", true},
+				{"gemini://example.com/subtree", false},
+				{"gemini://www.example.com/subtree/", true},
+				{"http://example.com/subtree/", true},
+			},
+		},
+		{
+			// scheme: gemini, hostname: *.example.com, path: /*
+			Pattern: "*.example.com",
+			Matches: []Match{
+				{"gemini://mail.example.com/", true},
+				{"gemini://www.example.com/index.gmi", true},
+				{"gemini://example.com/", false},
+				{"gemini://a.b.example.com/", false},
+				{"http://www.example.com/", false},
+			},
+		},
+		{
+			// scheme: http, hostname: *.example.com, path: /*
+			Pattern: "http://*.example.com",
+			Matches: []Match{
+				{"http://mail.example.com/", true},
+				{"http://www.example.com/index.gmi", true},
+				{"http://example.com/", false},
+				{"http://a.b.example.com/", false},
+				{"gemini://www.example.com/", false},
+			},
+		},
+	}
+
+	for i, test := range tests {
+		h := &nopHandler{}
+		var mux ServeMux
+		mux.Handle(test.Pattern, h)
+
+		for _, match := range tests[i].Matches {
+			u, err := url.Parse(match.URL)
+			if err != nil {
+				panic(err)
+			}
+			got := mux.Handler(&Request{URL: u})
+			if match.Ok {
+				if h != got {
+					t.Errorf("expected %s to match %s", test.Pattern, match.URL)
+				}
+			} else {
+				if h == got {
+					t.Errorf("expected %s not to match %s", test.Pattern, match.URL)
+				}
+			}
+		}
+	}
+}

query.go

@@ -5,13 +5,15 @@ import (
 	"strings"
 )
 
-// QueryEscape properly escapes a string for use in a Gemini URL query.
+// QueryEscape escapes a string for use in a Gemini URL query.
-// It is like url.PathEscape except that it also replaces plus signs with their percent-encoded counterpart.
+// It is like url.PathEscape except that it also replaces plus signs
+// with their percent-encoded counterpart.
 func QueryEscape(query string) string {
 	return strings.ReplaceAll(url.PathEscape(query), "+", "%2B")
 }
 
-// QueryUnescape is identical to url.PathUnescape.
+// QueryUnescape unescapes a Gemini URL query.
+// It is identical to url.PathUnescape.
 func QueryUnescape(query string) (string, error) {
 	return url.PathUnescape(query)
 }

request.go

@@ -2,82 +2,108 @@ package gemini
 
 import (
 	"bufio"
-	"context"
 	"crypto/tls"
+	"io"
 	"net"
 	"net/url"
 )
 
-// Request represents a Gemini request.
+// A Request represents a Gemini request received by a server or to be sent
+// by a client.
 type Request struct {
 	// URL specifies the URL being requested.
 	URL *url.URL
 
-	// For client requests, Host specifies the host on which the URL is sought.
+	// For client requests, Host optionally specifies the server to
-	// Host must contain a port.
+	// connect to. It may be of the form "host" or "host:port".
-	// This field is ignored by the server.
+	// If empty, the value of URL.Host is used.
+	// For international domain names, Host may be in Punycode or
+	// Unicode form. Use golang.org/x/net/idna to convert it to
+	// either format if needed.
+	// This field is ignored by the Gemini server.
 	Host string
 
-	// Certificate specifies the TLS certificate to use for the request.
+	// For client requests, Certificate optionally specifies the
-	// Request certificates take precedence over client certificates.
+	// TLS certificate to present to the other side of the connection.
-	//
+	// This field is ignored by the Gemini server.
-	// On the server side, if the client provided a certificate then
-	// Certificate.Leaf is guaranteed to be non-nil.
 	Certificate *tls.Certificate
 
-	// RemoteAddr allows servers and other software to record the network
+	conn net.Conn
-	// address that sent the request.
-	// This field is ignored by the client.
-	RemoteAddr net.Addr
-
-	// TLS allows servers and other software to record information about the TLS
-	// connection on which the request was received.
-	// This field is ignored by the client.
-	TLS tls.ConnectionState
-
-	// Context specifies the context to use for client requests.
-	// Context must not be nil.
-	Context context.Context
 }
 
-// NewRequest returns a new request. The host is inferred from the URL.
+// NewRequest returns a new request.
+// The returned Request is suitable for use with Client.Do.
+//
+// Callers should be careful that the URL query is properly escaped.
+// See the documentation for QueryEscape for more information.
 func NewRequest(rawurl string) (*Request, error) {
 	u, err := url.Parse(rawurl)
 	if err != nil {
 		return nil, err
 	}
-	return NewRequestFromURL(u), nil
+	return &Request{URL: u}, nil
 }
 
-// NewRequestFromURL returns a new request for the given URL.
+// ReadRequest reads and parses an incoming request from r.
-// The host is inferred from the URL.
 //
-// Callers should be careful that the URL query is properly escaped.
+// ReadRequest is a low-level function and should only be used
-// See the documentation for QueryEscape for more information.
+// for specialized applications; most code should use the Server
-func NewRequestFromURL(url *url.URL) *Request {
+// to read requests and handle them via the Handler interface.
-	host := url.Host
+func ReadRequest(r io.Reader) (*Request, error) {
-	if url.Port() == "" {
+	// Read URL
-		host += ":1965"
+	r = io.LimitReader(r, 1026)
+	br := bufio.NewReaderSize(r, 1026)
+	rawurl, err := br.ReadString('\r')
+	if err != nil {
+		return nil, err
 	}
-	return &Request{
+	// Read terminating line feed
-		URL:     url,
+	if b, err := br.ReadByte(); err != nil {
-		Host:    host,
+		return nil, err
-		Context: context.Background(),
+	} else if b != '\n' {
+		return nil, ErrInvalidRequest
 	}
+	// Trim carriage return
+	rawurl = rawurl[:len(rawurl)-1]
+	// Validate URL
+	if len(rawurl) > 1024 {
+		return nil, ErrInvalidRequest
+	}
+	u, err := url.Parse(rawurl)
+	if err != nil {
+		return nil, err
+	}
+	return &Request{URL: u}, nil
 }
 
-// write writes the Gemini request to the provided buffered writer.
+// Write writes a Gemini request in wire format.
-func (r *Request) write(w *bufio.Writer) error {
+// This method consults the request URL only.
+func (r *Request) Write(w io.Writer) error {
+	bw := bufio.NewWriterSize(w, 1026)
 	url := r.URL.String()
-	// User is invalid
+	if len(url) > 1024 {
-	if r.URL.User != nil || len(url) > 1024 {
+		return ErrInvalidRequest
-		return ErrInvalidURL
 	}
-	if _, err := w.WriteString(url); err != nil {
+	if _, err := bw.WriteString(url); err != nil {
 		return err
 	}
-	if _, err := w.Write(crlf); err != nil {
+	if _, err := bw.Write(crlf); err != nil {
 		return err
 	}
+	return bw.Flush()
+}
+
+// Conn returns the network connection on which the request was received.
+func (r *Request) Conn() net.Conn {
+	return r.conn
+}
+
+// TLS returns information about the TLS connection on which the
+// request was received.
+func (r *Request) TLS() *tls.ConnectionState {
+	if tlsConn, ok := r.conn.(*tls.Conn); ok {
+		state := tlsConn.ConnectionState()
+		return &state
+	}
 	return nil
 }

request_test.go

@@ -0,0 +1,132 @@
+package gemini
+
+import (
+	"bufio"
+	"io"
+	"net/url"
+	"strings"
+	"testing"
+)
+
+// 1024 bytes
+const maxURL = "gemini://example.net/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
+
+func TestReadRequest(t *testing.T) {
+	tests := []struct {
+		Raw string
+		URL *url.URL
+		Err error
+	}{
+		{
+			Raw: "gemini://example.com\r\n",
+			URL: &url.URL{
+				Scheme: "gemini",
+				Host:   "example.com",
+			},
+		},
+		{
+			Raw: "http://example.org/path/?query#fragment\r\n",
+			URL: &url.URL{
+				Scheme:   "http",
+				Host:     "example.org",
+				Path:     "/path/",
+				RawQuery: "query",
+				Fragment: "fragment",
+			},
+		},
+		{
+			Raw: "\r\n",
+			URL: &url.URL{},
+		},
+		{
+			Raw: "gemini://example.com\n",
+			Err: io.EOF,
+		},
+		{
+			Raw: "gemini://example.com",
+			Err: io.EOF,
+		},
+		{
+			// 1030 bytes
+			Raw: maxURL + "xxxxxx",
+			Err: io.EOF,
+		},
+		{
+			// 1027 bytes
+			Raw: maxURL + "x" + "\r\n",
+			Err: io.EOF,
+		},
+		{
+			// 1024 bytes
+			Raw: maxURL[:len(maxURL)-2] + "\r\n",
+			URL: &url.URL{
+				Scheme: "gemini",
+				Host:   "example.net",
+				Path:   maxURL[len("gemini://example.net") : len(maxURL)-2],
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Logf("%#v", test.Raw)
+		req, err := ReadRequest(strings.NewReader(test.Raw))
+		if err != test.Err {
+			t.Errorf("expected err = %v, got %v", test.Err, err)
+		}
+		if req == nil && test.URL != nil {
+			t.Errorf("expected url = %s, got nil", test.URL)
+		} else if req != nil && test.URL == nil {
+			t.Errorf("expected req = nil, got %v", req)
+		} else if req != nil && *req.URL != *test.URL {
+			t.Errorf("expected url = %v, got %v", *test.URL, *req.URL)
+		}
+	}
+}
+
+func newRequest(rawurl string) *Request {
+	req, err := NewRequest(rawurl)
+	if err != nil {
+		panic(err)
+	}
+	return req
+}
+
+func TestWriteRequest(t *testing.T) {
+	tests := []struct {
+		Req *Request
+		Raw string
+		Err error
+	}{
+		{
+			Req: newRequest("gemini://example.com"),
+			Raw: "gemini://example.com\r\n",
+		},
+		{
+			Req: newRequest("gemini://example.com/path/?query#fragment"),
+			Raw: "gemini://example.com/path/?query#fragment\r\n",
+		},
+		{
+			Req: newRequest(maxURL),
+			Raw: maxURL + "\r\n",
+		},
+		{
+			Req: newRequest(maxURL + "x"),
+			Err: ErrInvalidRequest,
+		},
+	}
+
+	for _, test := range tests {
+		t.Logf("%s", test.Req.URL)
+		var b strings.Builder
+		bw := bufio.NewWriter(&b)
+		err := test.Req.Write(bw)
+		if err != test.Err {
+			t.Errorf("expected err = %v, got %v", test.Err, err)
+		}
+		bw.Flush()
+		got := b.String()
+		if got != test.Raw {
+			t.Errorf("expected %#v, got %#v", test.Raw, got)
+		}
+	}
+}

response.go

@@ -4,112 +4,204 @@ import (
 	"bufio"
 	"crypto/tls"
 	"io"
+	"net"
 	"strconv"
 )
 
-// Response is a Gemini response.
+// The default media type for responses.
+const defaultMediaType = "text/gemini; charset=utf-8"
+
+// Response represents the response from a Gemini request.
+//
+// The Client returns Responses from servers once the response
+// header has been received. The response body is streamed on demand
+// as the Body field is read.
 type Response struct {
-	// Status contains the response status code.
+	// Status is the response status code.
 	Status Status
 
-	// Meta contains more information related to the response status.
+	// Meta returns the response meta.
-	// For successful responses, Meta should contain the mimetype of the response.
+	// For successful responses, the meta should contain the media type of the response.
-	// For failure responses, Meta should contain a short description of the failure.
+	// For failure responses, the meta should contain a short description of the failure.
-	// Meta should not be longer than 1024 bytes.
 	Meta string
 
-	// Body contains the response body for successful responses.
+	// Body represents the response body.
+	//
+	// The response body is streamed on demand as the Body field
+	// is read. If the network connection fails or the server
+	// terminates the response, Body.Read calls return an error.
+	//
+	// The Gemini client guarantees that Body is always
+	// non-nil, even on responses without a body or responses with
+	// a zero-length body. It is the caller's responsibility to
+	// close Body.
 	Body io.ReadCloser
 
-	// Request is the request that was sent to obtain this response.
+	conn net.Conn
-	Request *Request
-
-	// TLS contains information about the TLS connection on which the response
-	// was received.
-	TLS tls.ConnectionState
 }
 
-// read reads a Gemini response from the provided io.ReadCloser.
+// ReadResponse reads a Gemini response from the provided io.ReadCloser.
-func (resp *Response) read(rc io.ReadCloser) error {
+func ReadResponse(r io.ReadCloser) (*Response, error) {
-	br := bufio.NewReader(rc)
+	resp := &Response{}
+	br := bufio.NewReader(r)
+
 	// Read the status
 	statusB := make([]byte, 2)
 	if _, err := br.Read(statusB); err != nil {
-		return err
+		return nil, err
 	}
 	status, err := strconv.Atoi(string(statusB))
 	if err != nil {
-		return err
+		return nil, ErrInvalidResponse
 	}
 	resp.Status = Status(status)
 
-	// Disregard invalid status codes
-	const minStatus, maxStatus = 1, 6
-	statusClass := resp.Status.Class()
-	if statusClass < minStatus || statusClass > maxStatus {
-		return ErrInvalidResponse
-	}
-
 	// Read one space
 	if b, err := br.ReadByte(); err != nil {
-		return err
+		return nil, err
 	} else if b != ' ' {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
 
 	// Read the meta
 	meta, err := br.ReadString('\r')
 	if err != nil {
-		return err
+		return nil, err
 	}
 	// Trim carriage return
 	meta = meta[:len(meta)-1]
 	// Ensure meta is less than or equal to 1024 bytes
 	if len(meta) > 1024 {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
-	// Default mime type of text/gemini; charset=utf-8
+	if resp.Status.Class() == StatusSuccess && meta == "" {
-	if statusClass == StatusClassSuccess && meta == "" {
+		// Use default media type
-		meta = "text/gemini; charset=utf-8"
+		meta = defaultMediaType
 	}
 	resp.Meta = meta
 
 	// Read terminating newline
 	if b, err := br.ReadByte(); err != nil {
-		return err
+		return nil, err
 	} else if b != '\n' {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
 
-	if resp.Status.Class() == StatusClassSuccess {
+	if resp.Status.Class() == StatusSuccess {
-		resp.Body = newReadCloserBody(br, rc)
+		resp.Body = newBufReadCloser(br, r)
+	} else {
+		resp.Body = nopReadCloser{}
+		r.Close()
+	}
+	return resp, nil
+}
+
+// Conn returns the network connection on which the response was received.
+func (r *Response) Conn() net.Conn {
+	return r.conn
+}
+
+// TLS returns information about the TLS connection on which the
+// response was received.
+func (r *Response) TLS() *tls.ConnectionState {
+	if tlsConn, ok := r.conn.(*tls.Conn); ok {
+		state := tlsConn.ConnectionState()
+		return &state
 	}
 	return nil
 }
 
-type readCloserBody struct {
+// A ResponseWriter interface is used by a Gemini handler to construct
-	br *bufio.Reader // used until empty
+// a Gemini response.
-	io.ReadCloser
+//
+// A ResponseWriter may not be used after the Handler.ServeGemini method
+// has returned.
+type ResponseWriter interface {
+	// SetMediaType sets the media type that will be sent by Write for a
+	// successful response. If no media type is set, a default of
+	// "text/gemini; charset=utf-8" will be used.
+	//
+	// Setting the media type after a call to Write or WriteHeader has
+	// no effect.
+	SetMediaType(mediatype string)
+
+	// Write writes the data to the connection as part of a Gemini response.
+	//
+	// If WriteHeader has not yet been called, Write calls WriteHeader with
+	// StatusSuccess and the media type set in SetMediaType before writing the data.
+	// If no media type was set, Write uses a default media type of
+	// "text/gemini; charset=utf-8".
+	Write([]byte) (int, error)
+
+	// WriteHeader sends a Gemini response header with the provided
+	// status code and meta.
+	//
+	// If WriteHeader is not called explicitly, the first call to Write
+	// will trigger an implicit call to WriteHeader with a successful
+	// status code and the media type set in SetMediaType.
+	//
+	// The provided code must be a valid Gemini status code.
+	// The provided meta must not be longer than 1024 bytes.
+	// Only one header may be written.
+	WriteHeader(status Status, meta string)
+
+	// Flush sends any buffered data to the client.
+	Flush() error
 }
 
-func newReadCloserBody(br *bufio.Reader, rc io.ReadCloser) io.ReadCloser {
+type responseWriter struct {
-	body := &readCloserBody{ReadCloser: rc}
+	bw          *bufio.Writer
-	if br.Buffered() != 0 {
+	cl          io.Closer
-		body.br = br
+	mediatype   string
-	}
+	wroteHeader bool
-	return body
+	bodyAllowed bool
 }
 
-func (b *readCloserBody) Read(p []byte) (n int, err error) {
+func newResponseWriter(w io.Writer) *responseWriter {
-	if b.br != nil {
+	return &responseWriter{
-		if n := b.br.Buffered(); len(p) > n {
+		bw: bufio.NewWriter(w),
-			p = p[:n]
-		}
-		n, err = b.br.Read(p)
-		if b.br.Buffered() == 0 {
-			b.br = nil
-		}
-		return n, err
 	}
-	return b.ReadCloser.Read(p)
+}
+
+func (w *responseWriter) SetMediaType(mediatype string) {
+	w.mediatype = mediatype
+}
+
+func (w *responseWriter) Write(b []byte) (int, error) {
+	if !w.wroteHeader {
+		meta := w.mediatype
+		if meta == "" {
+			// Use default media type
+			meta = defaultMediaType
+		}
+		w.WriteHeader(StatusSuccess, meta)
+	}
+	if !w.bodyAllowed {
+		return 0, ErrBodyNotAllowed
+	}
+	return w.bw.Write(b)
+}
+
+func (w *responseWriter) WriteHeader(status Status, meta string) {
+	if w.wroteHeader {
+		return
+	}
+
+	if status.Class() == StatusSuccess {
+		w.bodyAllowed = true
+	}
+
+	w.bw.WriteString(strconv.Itoa(int(status)))
+	w.bw.WriteByte(' ')
+	w.bw.WriteString(meta)
+	w.bw.Write(crlf)
+	w.wroteHeader = true
+}
+
+func (w *responseWriter) Flush() error {
+	if !w.wroteHeader {
+		w.WriteHeader(StatusTemporaryFailure, "Temporary failure")
+	}
+	// Write errors from WriteHeader will be returned here.
+	return w.bw.Flush()
 }

response_test.go

@@ -0,0 +1,126 @@
+package gemini
+
+import (
+	"io"
+	"io/ioutil"
+	"strings"
+	"testing"
+)
+
+func TestReadWriteResponse(t *testing.T) {
+	tests := []struct {
+		Raw       string
+		Status    Status
+		Meta      string
+		Body      string
+		Err       error
+		SkipWrite bool
+	}{
+		{
+			Raw:    "20 text/gemini\r\nHello, world!\nWelcome to my capsule.",
+			Status: 20,
+			Meta:   "text/gemini",
+			Body:   "Hello, world!\nWelcome to my capsule.",
+		},
+		{
+			Raw:    "10 Search query\r\n",
+			Status: 10,
+			Meta:   "Search query",
+		},
+		{
+			Raw:    "30 /redirect\r\n",
+			Status: 30,
+			Meta:   "/redirect",
+		},
+		{
+			Raw:       "31 /redirect\r\nThis body is ignored.",
+			Status:    31,
+			Meta:      "/redirect",
+			SkipWrite: true, // skip write test since result won't match Raw
+		},
+		{
+			Raw:    "99 Unknown status code\r\n",
+			Status: 99,
+			Meta:   "Unknown status code",
+		},
+		{
+			Raw: "\r\n",
+			Err: ErrInvalidResponse,
+		},
+		{
+			Raw: "\n",
+			Err: ErrInvalidResponse,
+		},
+		{
+			Raw: "1 Bad response\r\n",
+			Err: ErrInvalidResponse,
+		},
+		{
+			Raw: "",
+			Err: io.EOF,
+		},
+		{
+			Raw: "10 Search query",
+			Err: io.EOF,
+		},
+		{
+			Raw: "20 text/gemini\nHello, world!",
+			Err: io.EOF,
+		},
+		{
+			Raw: "20 text/gemini\rHello, world!",
+			Err: ErrInvalidResponse,
+		},
+		{
+			Raw: "20 text/gemini\r",
+			Err: io.EOF,
+		},
+		{
+			Raw: "abcdefghijklmnopqrstuvwxyz",
+			Err: ErrInvalidResponse,
+		},
+	}
+
+	for _, test := range tests {
+		t.Logf("%#v", test.Raw)
+		resp, err := ReadResponse(ioutil.NopCloser(strings.NewReader(test.Raw)))
+		if err != test.Err {
+			t.Errorf("expected err = %v, got %v", test.Err, err)
+		}
+		if test.Err != nil {
+			// No response
+			continue
+		}
+		if resp.Status != test.Status {
+			t.Errorf("expected status = %d, got %d", test.Status, resp.Status)
+		}
+		if resp.Meta != test.Meta {
+			t.Errorf("expected meta = %s, got %s", test.Meta, resp.Meta)
+		}
+		b, _ := ioutil.ReadAll(resp.Body)
+		body := string(b)
+		if body != test.Body {
+			t.Errorf("expected body = %#v, got %#v", test.Body, body)
+		}
+	}
+
+	for _, test := range tests {
+		if test.Err != nil || test.SkipWrite {
+			continue
+		}
+
+		var b strings.Builder
+		w := newResponseWriter(nopCloser{&b})
+		w.WriteHeader(test.Status, test.Meta)
+		io.Copy(w, strings.NewReader(test.Body))
+		if err := w.Flush(); err != nil {
+			t.Error(err)
+			continue
+		}
+
+		got := b.String()
+		if got != test.Raw {
+			t.Errorf("expected %#v, got %#v", test.Raw, got)
+		}
+	}
+}

server.go

@@ -1,115 +1,267 @@
 package gemini
 
 import (
-	"bufio"
+	"context"
 	"crypto/tls"
 	"errors"
 	"log"
 	"net"
-	"net/url"
+	"sync"
-	"strconv"
-	"strings"
 	"time"
 )
 
-// Server is a Gemini server.
+// A Server defines parameters for running a Gemini server. The zero value for
+// Server is a valid configuration.
 type Server struct {
-	// Addr specifies the address that the server should listen on.
+	// Addr optionally specifies the TCP address for the server to listen on,
-	// If Addr is empty, the server will listen on the address ":1965".
+	// in the form "host:port". If empty, ":1965" (port 1965) is used.
+	// See net.Dial for details of the address format.
 	Addr string
 
-	// ReadTimeout is the maximum duration for reading a request.
+	// The Handler to invoke.
+	Handler Handler
+
+	// ReadTimeout is the maximum duration for reading the entire
+	// request.
+	//
+	// A ReadTimeout of zero means no timeout.
 	ReadTimeout time.Duration
 
 	// WriteTimeout is the maximum duration before timing out
 	// writes of the response.
+	//
+	// A WriteTimeout of zero means no timeout.
 	WriteTimeout time.Duration
 
-	// Certificates contains the certificates used by the server.
+	// GetCertificate returns a TLS certificate based on the given
-	Certificates CertificateDir
+	// hostname.
+	//
+	// If GetCertificate is nil or returns nil, then no certificate
+	// will be used and the connection will be aborted.
+	//
+	// See the certificate submodule for a certificate store that creates
+	// and rotates certificates as needed.
+	GetCertificate func(hostname string) (*tls.Certificate, error)
 
-	// CreateCertificate, if not nil, will be called to create a new certificate
+	// ErrorLog specifies an optional logger for errors accepting connections,
-	// if the current one is expired or missing.
+	// unexpected behavior from handlers, and underlying file system errors.
-	CreateCertificate func(hostname string) (tls.Certificate, error)
-
-	// ErrorLog specifies an optional logger for errors accepting connections
-	// and file system errors.
 	// If nil, logging is done via the log package's standard logger.
-	ErrorLog *log.Logger
+	ErrorLog interface {
+		Printf(format string, v ...interface{})
+	}
 
-	// registered responders
+	listeners map[*net.Listener]context.CancelFunc
-	responders map[responderKey]Responder
+	conns     map[*net.Conn]context.CancelFunc
-	hosts      map[string]bool
+	closed    bool // true if Close or Shutdown called
+	shutdown  bool // true if Shutdown called
+	doneChan  chan struct{}
+	mu        sync.Mutex
 }
 
-type responderKey struct {
+func (srv *Server) isClosed() bool {
-	scheme   string
+	srv.mu.Lock()
-	hostname string
+	defer srv.mu.Unlock()
+	return srv.closed
 }
 
-// Register registers a responder for the given pattern.
+// done returns a channel that's closed when the server is closed and
+// all listeners and connections are closed.
+func (srv *Server) done() chan struct{} {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	return srv.doneLocked()
+}
+
+func (srv *Server) doneLocked() chan struct{} {
+	if srv.doneChan == nil {
+		srv.doneChan = make(chan struct{})
+	}
+	return srv.doneChan
+}
+
+// tryCloseDone closes srv.done() if the server is closed and
+// there are no active listeners or connections.
+func (srv *Server) tryCloseDone() {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	srv.tryCloseDoneLocked()
+}
+
+func (srv *Server) tryCloseDoneLocked() {
+	if !srv.closed {
+		return
+	}
+	if len(srv.listeners) == 0 && len(srv.conns) == 0 {
+		ch := srv.doneLocked()
+		select {
+		case <-ch:
+		default:
+			close(ch)
+		}
+	}
+}
+
+// Close immediately closes all active net.Listeners and connections.
+// For a graceful shutdown, use Shutdown.
+func (srv *Server) Close() error {
+	srv.mu.Lock()
+	{
+		if srv.closed {
+			srv.mu.Unlock()
+			return nil
+		}
+		srv.closed = true
+
+		srv.tryCloseDoneLocked()
+
+		// Close all active connections and listeners.
+		for _, cancel := range srv.listeners {
+			cancel()
+		}
+		for _, cancel := range srv.conns {
+			cancel()
+		}
+	}
+	srv.mu.Unlock()
+
+	select {
+	case <-srv.done():
+		return nil
+	}
+}
+
+// Shutdown gracefully shuts down the server without interrupting any
+// active connections. Shutdown works by first closing all open listeners
+// and then waiting indefinitely for connections to close.
+// If the provided context expires before the shutdown is complete,
+// Shutdown returns the context's error.
 //
-// Patterns must be in the form of "hostname" or "scheme://hostname".
+// When Shutdown is called, Serve and ListenAndServe immediately
-// If no scheme is specified, a scheme of "gemini://" is implied.
+// return an error. Make sure the program doesn't exit and waits instead for
-// Wildcard patterns are supported (e.g. "*.example.com").
+// Shutdown to return.
-func (s *Server) Register(pattern string, responder Responder) {
+//
-	if pattern == "" {
+// Once Shutdown has been called on a server, it may not be reused;
-		panic("gemini: invalid pattern")
+// future calls to methods such as Serve will return an error.
-	}
+func (srv *Server) Shutdown(ctx context.Context) error {
-	if responder == nil {
+	srv.mu.Lock()
-		panic("gemini: nil responder")
+	{
-	}
+		if srv.closed {
-	if s.responders == nil {
+			srv.mu.Unlock()
-		s.responders = map[responderKey]Responder{}
+			return nil
-		s.hosts = map[string]bool{}
+		}
-	}
+		srv.closed = true
+		srv.shutdown = true
 
-	split := strings.SplitN(pattern, "://", 2)
+		srv.tryCloseDoneLocked()
-	var key responderKey
-	if len(split) == 2 {
-		key.scheme = split[0]
-		key.hostname = split[1]
-	} else {
-		key.scheme = "gemini"
-		key.hostname = split[0]
-	}
 
-	if _, ok := s.responders[key]; ok {
+		// Close all active listeners.
-		panic("gemini: multiple registrations for " + pattern)
+		for _, cancel := range srv.listeners {
+			cancel()
+		}
 	}
-	s.responders[key] = responder
+	srv.mu.Unlock()
-	s.hosts[key.hostname] = true
-}
 
-// RegisterFunc registers a responder function for the given pattern.
+	// Wait for active connections to finish.
-func (s *Server) RegisterFunc(pattern string, responder func(*ResponseWriter, *Request)) {
+	select {
-	s.Register(pattern, ResponderFunc(responder))
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-srv.done():
+		return nil
+	}
 }
 
 // ListenAndServe listens for requests at the server's configured address.
-func (s *Server) ListenAndServe() error {
+// ListenAndServe listens on the TCP network address srv.Addr and then calls
-	addr := s.Addr
+// Serve to handle requests on incoming connections. If the provided
+// context expires, ListenAndServe closes l and returns the context's error.
+//
+// If srv.Addr is blank, ":1965" is used.
+//
+// ListenAndServe always returns a non-nil error.
+// After Shutdown or Closed, the returned error is context.Canceled.
+func (srv *Server) ListenAndServe(ctx context.Context) error {
+	if srv.isClosed() {
+		return context.Canceled
+	}
+
+	addr := srv.Addr
 	if addr == "" {
 		addr = ":1965"
 	}
 
-	ln, err := net.Listen("tcp", addr)
+	l, err := net.Listen("tcp", addr)
 	if err != nil {
 		return err
 	}
-	defer ln.Close()
 
-	return s.Serve(tls.NewListener(ln, &tls.Config{
+	l = tls.NewListener(l, &tls.Config{
 		ClientAuth:     tls.RequestClientCert,
 		MinVersion:     tls.VersionTLS12,
-		GetCertificate: s.getCertificate,
+		GetCertificate: srv.getCertificate,
-	}))
+	})
+	return srv.Serve(ctx, l)
 }
 
-// Serve listens for requests on the provided listener.
+func (srv *Server) getCertificate(h *tls.ClientHelloInfo) (*tls.Certificate, error) {
-func (s *Server) Serve(l net.Listener) error {
+	if srv.GetCertificate == nil {
-	var tempDelay time.Duration // how long to sleep on accept failure
+		return nil, errors.New("gemini: GetCertificate is nil")
+	}
+	return srv.GetCertificate(h.ServerName)
+}
 
+func (srv *Server) trackListener(l *net.Listener, cancel context.CancelFunc) bool {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	if srv.closed {
+		return false
+	}
+	if srv.listeners == nil {
+		srv.listeners = make(map[*net.Listener]context.CancelFunc)
+	}
+	srv.listeners[l] = cancel
+	return true
+}
+
+func (srv *Server) deleteListener(l *net.Listener) {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	delete(srv.listeners, l)
+}
+
+// Serve accepts incoming connections on the Listener l, creating a new
+// service goroutine for each. The service goroutines read the requests and
+// then call the appropriate Handler to reply to them. If the provided
+// context expires, Serve closes l and returns the context's error.
+//
+// Serve always closes l and returns a non-nil error.
+// After Shutdown or Close, the returned error is context.Canceled.
+func (srv *Server) Serve(ctx context.Context, l net.Listener) error {
+	defer l.Close()
+
+	lnctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	if !srv.trackListener(&l, cancel) {
+		return context.Canceled
+	}
+	defer srv.tryCloseDone()
+	defer srv.deleteListener(&l)
+
+	errch := make(chan error, 1)
+	go func() {
+		errch <- srv.serve(ctx, l)
+	}()
+
+	select {
+	case <-lnctx.Done():
+		return lnctx.Err()
+	case err := <-errch:
+		return err
+	}
+}
+
+func (srv *Server) serve(ctx context.Context, l net.Listener) error {
+	var tempDelay time.Duration // how long to sleep on accept failure
 	for {
 		rw, err := l.Accept()
 		if err != nil {
@@ -123,235 +275,118 @@ func (s *Server) Serve(l net.Listener) error {
 				if max := 1 * time.Second; tempDelay > max {
 					tempDelay = max
 				}
-				s.logf("gemini: Accept error: %v; retrying in %v", err, tempDelay)
+				srv.logf("gemini: Accept error: %v; retrying in %v", err, tempDelay)
 				time.Sleep(tempDelay)
 				continue
 			}
-
-			// Otherwise, return the error
 			return err
 		}
-
 		tempDelay = 0
-		go s.respond(rw)
+		go srv.serveConn(ctx, rw, false)
 	}
 }
 
-func (s *Server) getCertificate(h *tls.ClientHelloInfo) (*tls.Certificate, error) {
+func (srv *Server) trackConn(conn *net.Conn, cancel context.CancelFunc, external bool) bool {
-	cert, err := s.getCertificateFor(h.ServerName)
+	srv.mu.Lock()
-	if err != nil {
+	defer srv.mu.Unlock()
-		// Try wildcard
+	// Reject the connection under the following conditions:
-		wildcard := strings.SplitN(h.ServerName, ".", 2)
+	// - Shutdown or Close has been called and conn is external (from ServeConn)
-		if len(wildcard) == 2 {
+	// - Close (not Shutdown) has been called and conn is internal (from Serve)
-			cert, err = s.getCertificateFor("*." + wildcard[1])
+	if srv.closed && (external || !srv.shutdown) {
-		}
+		return false
 	}
-	return cert, err
+	if srv.conns == nil {
+		srv.conns = make(map[*net.Conn]context.CancelFunc)
+	}
+	srv.conns[conn] = cancel
+	return true
 }
 
-func (s *Server) getCertificateFor(hostname string) (*tls.Certificate, error) {
+func (srv *Server) deleteConn(conn *net.Conn) {
-	if _, ok := s.hosts[hostname]; !ok {
+	srv.mu.Lock()
-		return nil, errors.New("hostname not registered")
+	defer srv.mu.Unlock()
-	}
+	delete(srv.conns, conn)
-
-	// Generate a new certificate if it is missing or expired
-	cert, ok := s.Certificates.Lookup(hostname)
-	if !ok || cert.Leaf != nil && cert.Leaf.NotAfter.Before(time.Now()) {
-		if s.CreateCertificate != nil {
-			cert, err := s.CreateCertificate(hostname)
-			if err == nil {
-				s.Certificates.Add(hostname, cert)
-				if err := s.Certificates.Write(hostname, cert); err != nil {
-					s.logf("gemini: Failed to write new certificate for %s: %s", hostname, err)
-				}
-			}
-			return &cert, err
-		}
-		return nil, errors.New("no certificate")
-	}
-	return &cert, nil
 }
 
-// respond responds to a connection.
+// ServeConn serves a Gemini response over the provided connection.
-func (s *Server) respond(conn net.Conn) {
+// It closes the connection when the response has been completed.
-	if d := s.ReadTimeout; d != 0 {
+// If the provided context expires before the response has completed,
+// ServeConn closes the connection and returns the context's error.
+func (srv *Server) ServeConn(ctx context.Context, conn net.Conn) error {
+	return srv.serveConn(ctx, conn, true)
+}
+
+func (srv *Server) serveConn(ctx context.Context, conn net.Conn, external bool) error {
+	defer conn.Close()
+
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	if !srv.trackConn(&conn, cancel, external) {
+		return context.Canceled
+	}
+	defer srv.tryCloseDone()
+	defer srv.deleteConn(&conn)
+
+	if d := srv.ReadTimeout; d != 0 {
 		conn.SetReadDeadline(time.Now().Add(d))
 	}
-	if d := s.WriteTimeout; d != 0 {
+	if d := srv.WriteTimeout; d != 0 {
 		conn.SetWriteDeadline(time.Now().Add(d))
 	}
 
-	r := bufio.NewReader(conn)
+	errch := make(chan error, 1)
-	w := newResponseWriter(conn)
+	go func() {
-	// Read requested URL
+		errch <- srv.goServeConn(ctx, conn)
-	rawurl, err := r.ReadString('\r')
+	}()
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case err := <-errch:
+		return err
+	}
+}
+
+func (srv *Server) goServeConn(ctx context.Context, conn net.Conn) error {
+	ctx, cancel := context.WithCancel(ctx)
+	done := ctx.Done()
+	cw := &contextWriter{
+		ctx:    ctx,
+		done:   done,
+		cancel: cancel,
+		wc:     conn,
+	}
+	r := &contextReader{
+		ctx:    ctx,
+		done:   done,
+		cancel: cancel,
+		rc:     conn,
+	}
+
+	w := newResponseWriter(cw)
+
+	req, err := ReadRequest(r)
 	if err != nil {
-		return
+		w.WriteHeader(StatusBadRequest, "Bad request")
+		return w.Flush()
 	}
-	// Read terminating line feed
+	req.conn = conn
-	if b, err := r.ReadByte(); err != nil {
-		return
-	} else if b != '\n' {
-		w.WriteStatus(StatusBadRequest)
-	}
-	// Trim carriage return
-	rawurl = rawurl[:len(rawurl)-1]
-	// Ensure URL is valid
-	if len(rawurl) > 1024 {
-		w.WriteStatus(StatusBadRequest)
-	} else if url, err := url.Parse(rawurl); err != nil || url.User != nil {
-		// Note that we return an error status if User is specified in the URL
-		w.WriteStatus(StatusBadRequest)
-	} else {
-		// Store information about the TLS connection
-		connState := conn.(*tls.Conn).ConnectionState()
-		var cert *tls.Certificate
-		if len(connState.PeerCertificates) > 0 {
-			peerCert := connState.PeerCertificates[0]
-			// Store the TLS certificate
-			cert = &tls.Certificate{
-				Certificate: [][]byte{peerCert.Raw},
-				Leaf:        peerCert,
-			}
-		}
 
-		req := &Request{
+	h := srv.Handler
-			URL:         url,
+	if h == nil {
-			RemoteAddr:  conn.RemoteAddr(),
+		w.WriteHeader(StatusNotFound, "Not found")
-			TLS:         connState,
+		return w.Flush()
-			Certificate: cert,
-		}
-		resp := s.responder(req)
-		if resp != nil {
-			resp.Respond(w, req)
-		} else {
-			w.WriteStatus(StatusNotFound)
-		}
 	}
-	w.b.Flush()
+
-	conn.Close()
+	h.ServeGemini(ctx, w, req)
+	return w.Flush()
 }
 
-func (s *Server) responder(r *Request) Responder {
+func (srv *Server) logf(format string, args ...interface{}) {
-	if h, ok := s.responders[responderKey{r.URL.Scheme, r.URL.Hostname()}]; ok {
+	if srv.ErrorLog != nil {
-		return h
+		srv.ErrorLog.Printf(format, args...)
-	}
-	wildcard := strings.SplitN(r.URL.Hostname(), ".", 2)
-	if len(wildcard) == 2 {
-		if h, ok := s.responders[responderKey{r.URL.Scheme, "*." + wildcard[1]}]; ok {
-			return h
-		}
-	}
-	return nil
-}
-
-func (s *Server) logf(format string, args ...interface{}) {
-	if s.ErrorLog != nil {
-		s.ErrorLog.Printf(format, args...)
 	} else {
 		log.Printf(format, args...)
 	}
 }
-
-// ResponseWriter is used by a Gemini handler to construct a Gemini response.
-type ResponseWriter struct {
-	b           *bufio.Writer
-	bodyAllowed bool
-	wroteHeader bool
-	mediatype   string
-}
-
-func newResponseWriter(conn net.Conn) *ResponseWriter {
-	return &ResponseWriter{
-		b: bufio.NewWriter(conn),
-	}
-}
-
-// WriteHeader writes the response header.
-// If the header has already been written, WriteHeader does nothing.
-//
-// Meta contains more information related to the response status.
-// For successful responses, Meta should contain the mimetype of the response.
-// For failure responses, Meta should contain a short description of the failure.
-// Meta should not be longer than 1024 bytes.
-func (w *ResponseWriter) WriteHeader(status Status, meta string) {
-	if w.wroteHeader {
-		return
-	}
-	w.b.WriteString(strconv.Itoa(int(status)))
-	w.b.WriteByte(' ')
-	w.b.WriteString(meta)
-	w.b.Write(crlf)
-
-	// Only allow body to be written on successful status codes.
-	if status.Class() == StatusClassSuccess {
-		w.bodyAllowed = true
-	}
-	w.wroteHeader = true
-}
-
-// WriteStatus writes the response header with the given status code.
-//
-// WriteStatus is equivalent to WriteHeader(status, status.Message())
-func (w *ResponseWriter) WriteStatus(status Status) {
-	w.WriteHeader(status, status.Message())
-}
-
-// SetMediaType sets the media type that will be written for a successful response.
-// If the mimetype is not set, it will default to "text/gemini".
-func (w *ResponseWriter) SetMediaType(mediatype string) {
-	w.mediatype = mediatype
-}
-
-// Write writes the response body.
-// If the response status does not allow for a response body, Write returns
-// ErrBodyNotAllowed.
-//
-// If the response header has not yet been written, Write calls WriteHeader
-// with StatusSuccess and the mimetype set in SetMimetype.
-func (w *ResponseWriter) Write(b []byte) (int, error) {
-	if !w.wroteHeader {
-		mediatype := w.mediatype
-		if mediatype == "" {
-			mediatype = "text/gemini"
-		}
-		w.WriteHeader(StatusSuccess, mediatype)
-	}
-	if !w.bodyAllowed {
-		return 0, ErrBodyNotAllowed
-	}
-	return w.b.Write(b)
-}
-
-// A Responder responds to a Gemini request.
-type Responder interface {
-	// Respond accepts a Request and constructs a Response.
-	Respond(*ResponseWriter, *Request)
-}
-
-// ResponderFunc is a wrapper around a bare function that implements Responder.
-type ResponderFunc func(*ResponseWriter, *Request)
-
-func (f ResponderFunc) Respond(w *ResponseWriter, r *Request) {
-	f(w, r)
-}
-
-// Input returns the request query.
-// If the query is invalid or no query is provided, ok will be false.
-//
-// Example:
-//
-//    input, ok := gemini.Input(req)
-//    if !ok {
-//        w.WriteHeader(gemini.StatusInput, "Prompt")
-//        return
-//    }
-//    // ...
-//
-func Input(r *Request) (query string, ok bool) {
-	if r.URL.ForceQuery || r.URL.RawQuery != "" {
-		query, err := url.QueryUnescape(r.URL.RawQuery)
-		return query, err == nil
-	}
-	return "", false
-}

status.go

@@ -1,8 +1,9 @@
 package gemini
 
-// Status codes.
+// Status represents a Gemini status code.
 type Status int
 
+// Gemini status codes.
 const (
 	StatusInput                    Status = 10
 	StatusSensitiveInput           Status = 11
@@ -24,25 +25,15 @@ const (
 	StatusCertificateNotValid      Status = 62
 )
 
-// Status code categories.
+// Class returns the status class for the status code.
-type StatusClass int
+// 1x becomes 10, 2x becomes 20, and so on.
-
+func (s Status) Class() Status {
-const (
+	return (s / 10) * 10
-	StatusClassInput               StatusClass = 1
-	StatusClassSuccess             StatusClass = 2
-	StatusClassRedirect            StatusClass = 3
-	StatusClassTemporaryFailure    StatusClass = 4
-	StatusClassPermanentFailure    StatusClass = 5
-	StatusClassCertificateRequired StatusClass = 6
-)
-
-// Class returns the status class for this status code.
-func (s Status) Class() StatusClass {
-	return StatusClass(s / 10)
 }
 
-// Message returns a status message corresponding to this status code.
+// String returns a text for the status code.
-func (s Status) Message() string {
+// It returns the empty string if the status code is unknown.
+func (s Status) String() string {
 	switch s {
 	case StatusInput:
 		return "Input"

text.go

@@ -9,38 +9,39 @@ import (
 
 // Line represents a line of a Gemini text response.
 type Line interface {
+	// String formats the line for use in a Gemini text response.
 	String() string
 	line() // private function to prevent other packages from implementing Line
 }
 
-// A link line.
+// LineLink is a link line.
 type LineLink struct {
 	URL  string
 	Name string
 }
 
-// A preformatting toggle line.
+// LinePreformattingToggle is a preformatting toggle line.
 type LinePreformattingToggle string
 
-// A preformatted text line.
+// LinePreformattedText is a preformatted text line.
 type LinePreformattedText string
 
-// A first-level heading line.
+// LineHeading1 is a first-level heading line.
 type LineHeading1 string
 
-// A second-level heading line.
+// LineHeading2 is a second-level heading line.
 type LineHeading2 string
 
-// A third-level heading line.
+// LineHeading3 is a third-level heading line.
 type LineHeading3 string
 
-// An unordered list item line.
+// LineListItem is an unordered list item line.
 type LineListItem string
 
-// A quote line.
+// LineQuote is a quote line.
 type LineQuote string
 
-// A text line.
+// LineText is a text line.
 type LineText string
 
 func (l LineLink) String() string {
@@ -88,17 +89,17 @@ func (l LineText) line()                {}
 type Text []Line
 
 // ParseText parses Gemini text from the provided io.Reader.
-func ParseText(r io.Reader) Text {
+func ParseText(r io.Reader) (Text, error) {
 	var t Text
-	ParseLines(r, func(line Line) {
+	err := ParseLines(r, func(line Line) {
 		t = append(t, line)
 	})
-	return t
+	return t, err
 }
 
 // ParseLines parses Gemini text from the provided io.Reader.
 // It calls handler with each line that it parses.
-func ParseLines(r io.Reader, handler func(Line)) {
+func ParseLines(r io.Reader, handler func(Line)) error {
 	const spacetab = " \t"
 	var pre bool
 	scanner := bufio.NewScanner(r)
@@ -149,6 +150,8 @@ func ParseLines(r io.Reader, handler func(Line)) {
 		}
 		handler(line)
 	}
+
+	return scanner.Err()
 }
 
 // String writes the Gemini text response to a string and returns it.

tofu.go

@@ -1,151 +0,0 @@
-package gemini
-
-import (
-	"bufio"
-	"crypto/sha512"
-	"fmt"
-	"io"
-	"os"
-	"strconv"
-	"strings"
-	"time"
-)
-
-// Trust represents the trustworthiness of a certificate.
-type Trust int
-
-const (
-	TrustNone   Trust = iota // The certificate is not trusted.
-	TrustOnce                // The certificate is trusted once.
-	TrustAlways              // The certificate is trusted always.
-)
-
-// KnownHosts maps hosts to fingerprints.
-type KnownHosts map[string]Fingerprint
-
-// KnownHostsFile represents a list of known hosts optionally loaded from a file.
-// The zero value for KnownHostsFile represents an empty list ready to use.
-type KnownHostsFile struct {
-	KnownHosts
-	out io.Writer
-}
-
-// SetOutput sets the output to which new known hosts will be written to.
-func (k *KnownHostsFile) SetOutput(w io.Writer) {
-	k.out = w
-}
-
-// Add adds a known host to the list of known hosts.
-func (k *KnownHostsFile) Add(hostname string, fingerprint Fingerprint) {
-	if k.KnownHosts == nil {
-		k.KnownHosts = KnownHosts{}
-	}
-	k.KnownHosts[hostname] = fingerprint
-}
-
-// Lookup returns the fingerprint of the certificate corresponding to
-// the given hostname.
-func (k *KnownHostsFile) Lookup(hostname string) (Fingerprint, bool) {
-	c, ok := k.KnownHosts[hostname]
-	return c, ok
-}
-
-// Write writes a known hosts entry to the configured output.
-func (k *KnownHostsFile) Write(hostname string, fingerprint Fingerprint) {
-	if k.out != nil {
-		k.writeKnownHost(k.out, hostname, fingerprint)
-	}
-}
-
-// WriteAll writes all of the known hosts to the provided io.Writer.
-func (k *KnownHostsFile) WriteAll(w io.Writer) error {
-	for h, c := range k.KnownHosts {
-		if _, err := k.writeKnownHost(w, h, c); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// writeKnownHost writes a known host to the provided io.Writer.
-func (k *KnownHostsFile) writeKnownHost(w io.Writer, hostname string, f Fingerprint) (int, error) {
-	return fmt.Fprintf(w, "%s %s %s %d\n", hostname, f.Algorithm, f.Hex, f.Expires.Unix())
-}
-
-// Load loads the known hosts from the provided path.
-// It creates the file if it does not exist.
-// New known hosts will be appended to the file.
-func (k *KnownHostsFile) Load(path string) error {
-	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDONLY, 0644)
-	if err != nil {
-		return err
-	}
-	k.Parse(f)
-	f.Close()
-	// Open the file for append-only use
-	f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
-	if err != nil {
-		return err
-	}
-	k.out = f
-	return nil
-}
-
-// Parse parses the provided reader and adds the parsed known hosts to the list.
-// Invalid entries are ignored.
-func (k *KnownHostsFile) Parse(r io.Reader) {
-	if k.KnownHosts == nil {
-		k.KnownHosts = map[string]Fingerprint{}
-	}
-	scanner := bufio.NewScanner(r)
-	for scanner.Scan() {
-		text := scanner.Text()
-		parts := strings.Split(text, " ")
-		if len(parts) < 4 {
-			continue
-		}
-
-		hostname := parts[0]
-		algorithm := parts[1]
-		if algorithm != "SHA-512" {
-			continue
-		}
-		hex := parts[2]
-
-		unix, err := strconv.ParseInt(parts[3], 10, 0)
-		if err != nil {
-			continue
-		}
-		expires := time.Unix(unix, 0)
-
-		k.KnownHosts[hostname] = Fingerprint{
-			Algorithm: algorithm,
-			Hex:       hex,
-			Expires:   expires,
-		}
-	}
-}
-
-// Fingerprint represents a fingerprint using a certain algorithm.
-type Fingerprint struct {
-	Algorithm string    // fingerprint algorithm e.g. SHA-512
-	Hex       string    // fingerprint in hexadecimal, with ':' between each octet
-	Expires   time.Time // unix time of the fingerprint expiration date
-}
-
-// NewFingerprint returns the SHA-512 fingerprint of the provided raw data.
-func NewFingerprint(raw []byte, expires time.Time) Fingerprint {
-	sum512 := sha512.Sum512(raw)
-	var b strings.Builder
-	for i, f := range sum512 {
-		if i > 0 {
-			b.WriteByte(':')
-		}
-		fmt.Fprintf(&b, "%02X", f)
-	}
-	return Fingerprint{
-		Algorithm: "SHA-512",
-		Hex:       b.String(),
-		Expires:   expires,
-	}
-}

tofu/tofu.go

@@ -0,0 +1,418 @@
+// Package tofu implements trust on first use using hosts and fingerprints.
+package tofu
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/sha512"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+// KnownHosts represents a list of known hosts.
+// The zero value for KnownHosts represents an empty list ready to use.
+//
+// KnownHosts is safe for concurrent use by multiple goroutines.
+type KnownHosts struct {
+	hosts map[string]Host
+	mu    sync.RWMutex
+}
+
+// Add adds a host to the list of known hosts.
+func (k *KnownHosts) Add(h Host) {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	if k.hosts == nil {
+		k.hosts = map[string]Host{}
+	}
+
+	k.hosts[h.Hostname] = h
+}
+
+// Lookup returns the known host entry corresponding to the given hostname.
+func (k *KnownHosts) Lookup(hostname string) (Host, bool) {
+	k.mu.RLock()
+	defer k.mu.RUnlock()
+	c, ok := k.hosts[hostname]
+	return c, ok
+}
+
+// Entries returns the known host entries sorted by hostname.
+func (k *KnownHosts) Entries() []Host {
+	keys := make([]string, 0, len(k.hosts))
+	for key := range k.hosts {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	hosts := make([]Host, 0, len(k.hosts))
+	for _, key := range keys {
+		hosts = append(hosts, k.hosts[key])
+	}
+	return hosts
+}
+
+// WriteTo writes the list of known hosts to the provided io.Writer.
+func (k *KnownHosts) WriteTo(w io.Writer) (int64, error) {
+	k.mu.RLock()
+	defer k.mu.RUnlock()
+
+	var written int
+
+	bw := bufio.NewWriter(w)
+	for _, h := range k.hosts {
+		n, err := bw.WriteString(h.String())
+		written += n
+		if err != nil {
+			return int64(written), err
+		}
+
+		bw.WriteByte('\n')
+		written += 1
+	}
+
+	return int64(written), bw.Flush()
+}
+
+// Load loads the known hosts entries from the provided path.
+func (k *KnownHosts) Load(path string) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return k.Parse(f)
+}
+
+// Parse parses the provided io.Reader and adds the parsed hosts to the list.
+// Invalid entries are ignored.
+//
+// For more control over errors encountered during parsing, use bufio.Scanner
+// in combination with ParseHost. For example:
+//
+//    var knownHosts tofu.KnownHosts
+//    scanner := bufio.NewScanner(r)
+//    for scanner.Scan() {
+//        host, err := tofu.ParseHost(scanner.Bytes())
+//        if err != nil {
+//            // handle error
+//        } else {
+//            knownHosts.Add(host)
+//        }
+//    }
+//    err := scanner.Err()
+//    if err != nil {
+//        // handle error
+//    }
+//
+func (k *KnownHosts) Parse(r io.Reader) error {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+
+	if k.hosts == nil {
+		k.hosts = map[string]Host{}
+	}
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		text := scanner.Bytes()
+		if len(text) == 0 {
+			continue
+		}
+
+		h, err := ParseHost(text)
+		if err != nil {
+			continue
+		}
+
+		k.hosts[h.Hostname] = h
+	}
+
+	return scanner.Err()
+}
+
+// TOFU implements basic trust on first use.
+//
+// If the host is not on file, it is added to the list.
+// If the host on file is expired, a new entry is added to the list.
+// If the fingerprint does not match the one on file, an error is returned.
+func (k *KnownHosts) TOFU(hostname string, cert *x509.Certificate) error {
+	host := NewHost(hostname, cert.Raw, cert.NotAfter)
+
+	knownHost, ok := k.Lookup(hostname)
+	if !ok || time.Now().After(knownHost.Expires) {
+		k.Add(host)
+		return nil
+	}
+
+	// Check fingerprint
+	if !bytes.Equal(knownHost.Fingerprint, host.Fingerprint) {
+		return fmt.Errorf("fingerprint for %q does not match", hostname)
+	}
+
+	return nil
+}
+
+// HostWriter writes host entries to an io.WriteCloser.
+//
+// HostWriter is safe for concurrent use by multiple goroutines.
+type HostWriter struct {
+	bw *bufio.Writer
+	cl io.Closer
+	mu sync.Mutex
+}
+
+// NewHostWriter returns a new host writer that writes to
+// the provided io.WriteCloser.
+func NewHostWriter(w io.WriteCloser) *HostWriter {
+	return &HostWriter{
+		bw: bufio.NewWriter(w),
+		cl: w,
+	}
+}
+
+// OpenHostsFile returns a new host writer that appends to the file at the given path.
+// The file is created if it does not exist.
+func OpenHostsFile(path string) (*HostWriter, error) {
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return nil, err
+	}
+	return NewHostWriter(f), nil
+}
+
+// WriteHost writes the host to the underlying io.Writer.
+func (h *HostWriter) WriteHost(host Host) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	h.bw.WriteString(host.String())
+	h.bw.WriteByte('\n')
+
+	if err := h.bw.Flush(); err != nil {
+		return fmt.Errorf("failed to write host: %w", err)
+	}
+	return nil
+}
+
+// Close closes the underlying io.Closer.
+func (h *HostWriter) Close() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return h.cl.Close()
+}
+
+// PersistentHosts represents a persistent set of known hosts.
+type PersistentHosts struct {
+	hosts  *KnownHosts
+	writer *HostWriter
+}
+
+// NewPersistentHosts returns a new persistent set of known hosts that stores
+// known hosts in hosts and writes new hosts to writer.
+func NewPersistentHosts(hosts *KnownHosts, writer *HostWriter) *PersistentHosts {
+	return &PersistentHosts{
+		hosts,
+		writer,
+	}
+}
+
+// LoadPersistentHosts loads persistent hosts from the file at the given path.
+func LoadPersistentHosts(path string) (*PersistentHosts, error) {
+	hosts := &KnownHosts{}
+	if err := hosts.Load(path); err != nil {
+		return nil, err
+	}
+	writer, err := OpenHostsFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return &PersistentHosts{
+		hosts,
+		writer,
+	}, nil
+}
+
+// Add adds a host to the list of known hosts.
+// It returns an error if the host could not be persisted.
+func (p *PersistentHosts) Add(h Host) error {
+	err := p.writer.WriteHost(h)
+	if err != nil {
+		return fmt.Errorf("failed to persist host: %w", err)
+	}
+	p.hosts.Add(h)
+	return nil
+}
+
+// Lookup returns the known host entry corresponding to the given hostname.
+func (p *PersistentHosts) Lookup(hostname string) (Host, bool) {
+	return p.hosts.Lookup(hostname)
+}
+
+// Entries returns the known host entries sorted by hostname.
+func (p *PersistentHosts) Entries() []Host {
+	return p.hosts.Entries()
+}
+
+// TOFU implements trust on first use with a persistent set of known hosts.
+//
+// If the host is not on file, it is added to the list.
+// If the host on file is expired, a new entry is added to the list.
+// If the fingerprint does not match the one on file, an error is returned.
+func (p *PersistentHosts) TOFU(hostname string, cert *x509.Certificate) error {
+	host := NewHost(hostname, cert.Raw, cert.NotAfter)
+
+	knownHost, ok := p.Lookup(hostname)
+	if !ok || time.Now().After(knownHost.Expires) {
+		return p.Add(host)
+	}
+
+	// Check fingerprint
+	if !bytes.Equal(knownHost.Fingerprint, host.Fingerprint) {
+		return fmt.Errorf("fingerprint for %q does not match", hostname)
+	}
+
+	return nil
+}
+
+// Close closes the underlying HostWriter.
+func (p *PersistentHosts) Close() error {
+	return p.writer.Close()
+}
+
+// Host represents a host entry with a fingerprint using a certain algorithm.
+type Host struct {
+	Hostname    string      // hostname
+	Algorithm   string      // fingerprint algorithm e.g. SHA-512
+	Fingerprint Fingerprint // fingerprint
+	Expires     time.Time   // unix time of the fingerprint expiration date
+}
+
+// NewHost returns a new host with a SHA-512 fingerprint of
+// the provided raw data.
+func NewHost(hostname string, raw []byte, expires time.Time) Host {
+	sum := sha512.Sum512(raw)
+
+	return Host{
+		Hostname:    hostname,
+		Algorithm:   "SHA-512",
+		Fingerprint: sum[:],
+		Expires:     expires,
+	}
+}
+
+// ParseHost parses a host from the provided text.
+func ParseHost(text []byte) (Host, error) {
+	var h Host
+	err := h.UnmarshalText(text)
+	return h, err
+}
+
+// String returns a string representation of the host.
+func (h Host) String() string {
+	var b strings.Builder
+	b.WriteString(h.Hostname)
+	b.WriteByte(' ')
+	b.WriteString(h.Algorithm)
+	b.WriteByte(' ')
+	b.WriteString(h.Fingerprint.String())
+	b.WriteByte(' ')
+	b.WriteString(strconv.FormatInt(h.Expires.Unix(), 10))
+	return b.String()
+}
+
+// UnmarshalText unmarshals the host from the provided text.
+func (h *Host) UnmarshalText(text []byte) error {
+	const format = "hostname algorithm hex-fingerprint expiry-unix-ts"
+
+	parts := bytes.Split(text, []byte(" "))
+	if len(parts) != 4 {
+		return fmt.Errorf("expected the format %q", format)
+	}
+
+	if len(parts[0]) == 0 {
+		return errors.New("empty hostname")
+	}
+
+	h.Hostname = string(parts[0])
+
+	algorithm := string(parts[1])
+	if algorithm != "SHA-512" {
+		return fmt.Errorf("unsupported algorithm %q", algorithm)
+	}
+
+	h.Algorithm = algorithm
+
+	fingerprint := make([]byte, 0, sha512.Size)
+	scanner := bufio.NewScanner(bytes.NewReader(parts[2]))
+	scanner.Split(scanFingerprint)
+
+	for scanner.Scan() {
+		b, err := strconv.ParseUint(scanner.Text(), 16, 8)
+		if err != nil {
+			return fmt.Errorf("failed to parse fingerprint hash: %w", err)
+		}
+		fingerprint = append(fingerprint, byte(b))
+	}
+
+	if len(fingerprint) != sha512.Size {
+		return fmt.Errorf("invalid fingerprint size %d, expected %d",
+			len(fingerprint), sha512.Size)
+	}
+
+	h.Fingerprint = fingerprint
+
+	unix, err := strconv.ParseInt(string(parts[3]), 10, 0)
+	if err != nil {
+		return fmt.Errorf("invalid unix timestamp: %w", err)
+	}
+
+	h.Expires = time.Unix(unix, 0)
+
+	return nil
+}
+
+func scanFingerprint(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	if atEOF && len(data) == 0 {
+		return 0, nil, nil
+	}
+	if i := bytes.IndexByte(data, ':'); i >= 0 {
+		// We have a full newline-terminated line.
+		return i + 1, data[0:i], nil
+	}
+
+	// If we're at EOF, we have a final, non-terminated hex byte
+	if atEOF {
+		return len(data), data, nil
+	}
+
+	// Request more data.
+	return 0, nil, nil
+}
+
+// Fingerprint represents a fingerprint.
+type Fingerprint []byte
+
+// String returns a string representation of the fingerprint.
+func (f Fingerprint) String() string {
+	var sb strings.Builder
+
+	for i, b := range f {
+		if i > 0 {
+			sb.WriteByte(':')
+		}
+
+		fmt.Fprintf(&sb, "%02X", b)
+	}
+
+	return sb.String()
+}