examples/client: Fix fingerprint check

Use (*ResponseWriter).WriteHeader instead.

cert.go

@@ -2,28 +2,44 @@ package gemini
 
 import (
 	"crypto"
+	"crypto/ecdsa"
 	"crypto/ed25519"
+	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
 	"math/big"
 	"net"
+	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 )
 
-// CertificateStore maps hostnames to certificates.
-// The zero value of CertificateStore is an empty store ready to use.
-type CertificateStore struct {
-	store map[string]tls.Certificate
+// CertificateDir maps certificate scopes to certificates.
+type CertificateStore map[string]tls.Certificate
+
+// CertificateDir represents a certificate store optionally loaded from a directory.
+// The zero value of CertificateDir is an empty store ready to use.
+//
+// CertificateDir is safe for concurrent use by multiple goroutines.
+type CertificateDir struct {
+	CertificateStore
+	dir  bool
+	path string
+	mu   sync.RWMutex
 }
 
-// Add adds a certificate for the given hostname to the store.
+// 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 *CertificateStore) Add(hostname string, cert tls.Certificate) {
-	if c.store == nil {
-		c.store = map[string]tls.Certificate{}
+func (c *CertificateDir) Add(scope string, cert tls.Certificate) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.CertificateStore == nil {
+		c.CertificateStore = CertificateStore{}
 	}
 	// Parse certificate if not already parsed
 	if cert.Leaf == nil {
@@ -32,28 +48,40 @@ func (c *CertificateStore) Add(hostname string, cert tls.Certificate) {
 			cert.Leaf = parsed
 		}
 	}
-	c.store[hostname] = cert
+	c.CertificateStore[scope] = cert
 }
 
-// Lookup returns the certificate for the given hostname.
-func (c *CertificateStore) Lookup(hostname string) (*tls.Certificate, error) {
-	cert, ok := c.store[hostname]
-	if !ok {
-		return nil, ErrCertificateUnknown
+// Write writes the provided certificate to the certificate directory.
+func (c *CertificateDir) Write(scope string, cert tls.Certificate) error {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	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
+		}
 	}
-	// Ensure that the certificate is not expired
-	if cert.Leaf != nil && cert.Leaf.NotAfter.Before(time.Now()) {
-		return &cert, ErrCertificateExpired
-	}
-	return &cert, nil
+	return nil
+}
+
+// Lookup returns the certificate for the given scope.
+func (c *CertificateDir) Lookup(scope string) (tls.Certificate, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	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 hostname.crt and hostname.key.
+// 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).
-func (c *CertificateStore) Load(path string) error {
+// 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
@@ -64,15 +92,53 @@ func (c *CertificateStore) Load(path string) error {
 		if err != nil {
 			continue
 		}
-		hostname := strings.TrimSuffix(filepath.Base(crtPath), ".crt")
-		c.Add(hostname, cert)
+		scope := strings.TrimSuffix(filepath.Base(crtPath), ".crt")
+		// Unescape slash character
+		scope = strings.ReplaceAll(scope, ":", "/")
+		c.Add(scope, cert)
 	}
+	c.SetDir(path)
 	return nil
 }
 
-// NewCertificate creates and returns a new parsed certificate.
-func NewCertificate(host string, duration time.Duration) (tls.Certificate, error) {
-	crt, priv, err := newX509KeyPair(host, duration)
+// SetDir sets the directory that new certificates will be written to.
+func (c *CertificateDir) SetDir(path string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	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 specifies the certificate Subject.
+	//
+	// Subject.CommonName can contain the DNS name that this certificate
+	// is valid for. Server certificates should specify both a Subject
+	// and a Subject Alternate Name.
+	Subject pkix.Name
+
+	// Duration specifies the amount of time that the certificate is valid for.
+	Duration time.Duration
+
+	// Ed25519 specifies whether to generate an Ed25519 key pair.
+	// If false, an ECDSA key will be generated instead.
+	// Ed25519 is not as widely supported as ECDSA.
+	Ed25519 bool
+}
+
+// CreateCertificate creates a new TLS certificate.
+func CreateCertificate(options CertificateOptions) (tls.Certificate, error) {
+	crt, priv, err := newX509KeyPair(options)
 	if err != nil {
 		return tls.Certificate{}, err
 	}
@@ -84,16 +150,28 @@ func NewCertificate(host string, duration time.Duration) (tls.Certificate, error
 }
 
 // newX509KeyPair creates and returns a new certificate and private key.
-func newX509KeyPair(host string, duration time.Duration) (*x509.Certificate, crypto.PrivateKey, error) {
-	// Generate an ED25519 private key
-	_, priv, err := ed25519.GenerateKey(rand.Reader)
-	if err != nil {
-		return nil, nil, err
+func newX509KeyPair(options CertificateOptions) (*x509.Certificate, crypto.PrivateKey, error) {
+	var pub crypto.PublicKey
+	var priv crypto.PrivateKey
+	if options.Ed25519 {
+		// Generate an Ed25519 private key
+		var err error
+		pub, priv, err = ed25519.GenerateKey(rand.Reader)
+		if err != nil {
+			return nil, nil, err
+		}
+	} else {
+		// Generate an ECDSA private key
+		private, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+		if err != nil {
+			return nil, nil, err
+		}
+		priv = private
+		pub = &private.PublicKey
 	}
-	public := priv.Public()
 
-	// ED25519 keys should have the DigitalSignature KeyUsage bits set
-	// in the x509.Certificate template
+	// ECDSA and Ed25519 keys should have the DigitalSignature KeyUsage bits
+	// set in the x509.Certificate template
 	keyUsage := x509.KeyUsageDigitalSignature
 
 	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
@@ -103,7 +181,7 @@ func newX509KeyPair(host string, duration time.Duration) (*x509.Certificate, cry
 	}
 
 	notBefore := time.Now()
-	notAfter := notBefore.Add(duration)
+	notAfter := notBefore.Add(options.Duration)
 
 	template := x509.Certificate{
 		SerialNumber:          serialNumber,
@@ -112,18 +190,12 @@ func newX509KeyPair(host string, duration time.Duration) (*x509.Certificate, cry
 		KeyUsage:              keyUsage,
 		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
 		BasicConstraintsValid: true,
+		IPAddresses:           options.IPAddresses,
+		DNSNames:              options.DNSNames,
+		Subject:               options.Subject,
 	}
 
-	hosts := strings.Split(host, ",")
-	for _, h := range hosts {
-		if ip := net.ParseIP(h); ip != nil {
-			template.IPAddresses = append(template.IPAddresses, ip)
-		} else {
-			template.DNSNames = append(template.DNSNames, h)
-		}
-	}
-
-	crt, err := x509.CreateCertificate(rand.Reader, &template, &template, public, priv)
+	crt, err := x509.CreateCertificate(rand.Reader, &template, &template, pub, priv)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -133,3 +205,30 @@ func newX509KeyPair(host string, duration time.Duration) (*x509.Certificate, cry
 	}
 	return cert, priv, nil
 }
+
+// WriteCertificate writes the provided certificate and private key
+// to certPath and keyPath respectively.
+func WriteCertificate(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
+	}
+	defer certOut.Close()
+	if err := pem.Encode(certOut, &pem.Block{
+		Type:  "CERTIFICATE",
+		Bytes: cert.Leaf.Raw,
+	}); err != nil {
+		return err
+	}
+
+	keyOut, err := os.OpenFile(keyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		return err
+	}
+	defer keyOut.Close()
+	privBytes, err := x509.MarshalPKCS8PrivateKey(cert.PrivateKey)
+	if err != nil {
+		return err
+	}
+	return pem.Encode(keyOut, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes})
+}

client.go

@@ -2,101 +2,119 @@ package gemini
 
 import (
 	"bufio"
+	"context"
 	"crypto/tls"
 	"crypto/x509"
+	"errors"
+	"net"
+	"strings"
+	"time"
 )
 
-// Client represents a Gemini client.
+// Client is a Gemini client.
 type Client struct {
-	// KnownHosts is a list of known hosts that the client trusts.
-	KnownHosts KnownHosts
+	// TrustCertificate is called to determine whether the client
+	// should trust the certificate provided by the server.
+	// If TrustCertificate is nil, the client will accept any certificate.
+	// If the returned error is not nil, the certificate will not be trusted
+	// and the request will be aborted.
+	TrustCertificate func(hostname string, cert *x509.Certificate) error
 
-	// CertificateStore maps hostnames to certificates.
-	// It is used to determine which certificate to use when the server requests
-	// a certificate.
-	CertificateStore CertificateStore
-
-	// GetCertificate, if not nil, will be called when a server requests a certificate.
-	// The returned certificate will be used when sending the request again.
-	// If the certificate is nil, the request will not be sent again and
-	// the response will be returned.
-	GetCertificate func(hostname string, store *CertificateStore) *tls.Certificate
-
-	// TrustCertificate, if not nil, will be called to determine whether the
-	// client should trust the given certificate.
-	// If error is not nil, the connection will be aborted.
-	TrustCertificate func(hostname string, cert *x509.Certificate, knownHosts *KnownHosts) error
+	// 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.
+	Timeout time.Duration
 }
 
-// Send sends a Gemini request and returns a Gemini response.
-func (c *Client) Send(req *Request) (*Response, error) {
+// Get performs a Gemini request for the given URL.
+func (c *Client) Get(url string) (*Response, error) {
+	req, err := NewRequest(url)
+	if err != nil {
+		return nil, err
+	}
+	return c.Do(req)
+}
+
+// Do performs a Gemini request and returns a Gemini response.
+func (c *Client) Do(req *Request) (*Response, error) {
+	// Extract hostname
+	colonPos := strings.LastIndex(req.Host, ":")
+	if colonPos == -1 {
+		colonPos = len(req.Host)
+	}
+	hostname := req.Host[:colonPos]
+
 	// Connect to the host
 	config := &tls.Config{
 		InsecureSkipVerify: true,
 		MinVersion:         tls.VersionTLS12,
-		GetClientCertificate: func(info *tls.CertificateRequestInfo) (*tls.Certificate, error) {
-			// Request certificates take precedence over client certificates
+		GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
 			if req.Certificate != nil {
 				return req.Certificate, nil
 			}
-			// If we have already stored the certificate, return it
-			if cert, err := c.CertificateStore.Lookup(hostname(req.Host)); err == nil {
-				return cert, nil
-			}
 			return &tls.Certificate{}, nil
 		},
 		VerifyConnection: func(cs tls.ConnectionState) error {
-			cert := cs.PeerCertificates[0]
-			// Verify the hostname
-			if err := verifyHostname(cert, hostname(req.Host)); err != nil {
-				return err
-			}
-			// Check that the client trusts the certificate
-			if c.TrustCertificate == nil {
-				if err := c.KnownHosts.Lookup(hostname(req.Host), cert); err != nil {
-					return err
-				}
-			} else if err := c.TrustCertificate(hostname(req.Host), cert, &c.KnownHosts); err != nil {
-				return err
-			}
-			return nil
+			return c.verifyConnection(req, cs)
 		},
+		ServerName: hostname,
 	}
-	conn, err := tls.Dial("tcp", req.Host, config)
+	// Set connection context
+	ctx := req.Context
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	netConn, err := (&net.Dialer{}).DialContext(ctx, "tcp", req.Host)
 	if err != nil {
 		return nil, err
 	}
-	defer conn.Close()
+	conn := tls.Client(netConn, config)
+	// Set connection deadline
+	if c.Timeout != 0 {
+		conn.SetDeadline(time.Now().Add(c.Timeout))
+	}
 
 	// Write the request
 	w := bufio.NewWriter(conn)
-	req.write(w)
+	req.Write(w)
 	if err := w.Flush(); err != nil {
 		return nil, err
 	}
 
 	// Read the response
-	resp := &Response{}
-	r := bufio.NewReader(conn)
-	if err := resp.read(r); err != nil {
+	resp, err := ReadResponse(conn)
+	if err != nil {
 		return nil, err
 	}
-	// Store connection information
+	// Store connection state
 	resp.TLS = conn.ConnectionState()
 
-	// Resend the request with a certificate if the server responded
-	// with CertificateRequired
-	if resp.Status == StatusCertificateRequired {
-		// Check to see if a certificate was already provided to prevent an infinite loop
-		if req.Certificate != nil {
-			return resp, nil
-		}
-		if c.GetCertificate != nil {
-			if cert := c.GetCertificate(hostname(req.Host), &c.CertificateStore); cert != nil {
-				req.Certificate = cert
-				return c.Send(req)
-			}
-		}
-	}
 	return resp, nil
 }
+
+func (c *Client) verifyConnection(req *Request, cs tls.ConnectionState) 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]
+	if err := verifyHostname(cert, hostname); err != nil {
+		return err
+	}
+	// Check expiration date
+	if !time.Now().Before(cert.NotAfter) {
+		return errors.New("gemini: certificate expired")
+	}
+
+	// See if the client trusts the certificate
+	if c.TrustCertificate != nil {
+		return c.TrustCertificate(hostname, cert)
+	}
+	return nil
+}

doc.go

@@ -1,84 +0,0 @@
-/*
-Package gemini implements the Gemini protocol.
-
-Send makes a Gemini request with the default client:
-
-	req := gemini.NewRequest("gemini://example.com")
-	resp, err := gemini.Send(req)
-	if err != nil {
-		// handle error
-	}
-	// ...
-
-For control over client behavior, create a custom Client:
-
-	var client gemini.Client
-	resp, err := client.Send(req)
-	if err != nil {
-		// handle error
-	}
-	// ...
-
-The default client loads known hosts from "$XDG_DATA_HOME/gemini/known_hosts".
-Custom clients can load their own list of known hosts:
-
-	err := client.KnownHosts.Load("path/to/my/known_hosts")
-	if err != nil {
-		// handle error
-	}
-
-Clients can control when to trust certificates with TrustCertificate:
-
-	client.TrustCertificate = func(hostname string, cert *x509.Certificate, knownHosts *gemini.KnownHosts) error {
-		return knownHosts.Lookup(hostname, cert)
-	}
-
-If a server responds with StatusCertificateRequired, the default client will generate a certificate and resend the request with it. Custom clients can do so in GetCertificate:
-
-	client.GetCertificate = func(hostname string, store *gemini.CertificateStore) *tls.Certificate {
-		// If the certificate is in the store, return it
-		if cert, err := store.Lookup(hostname); err == nil {
-			return &cert
-		}
-		// Otherwise, generate a certificate
-		duration := time.Hour
-		cert, err := gemini.NewCertificate(hostname, duration)
-		if err != nil {
-			return nil
-		}
-		// Store and return the certificate
-		store.Add(hostname, cert)
-		return &cert
-	}
-
-Server is a Gemini server.
-
-	var server gemini.Server
-
-Servers must be configured with certificates:
-
-	err := server.CertificateStore.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

examples/auth.go

@@ -3,48 +3,44 @@
 package main
 
 import (
+	"crypto/sha512"
+	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
 	"fmt"
 	"log"
+	"time"
 
-	gmi "git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini"
 )
 
-type user struct {
-	password string // TODO: use hashes
-	admin    bool
-}
-
-type session struct {
-	username   string
-	authorized bool // whether or not the password was supplied
+type User struct {
+	Name string
 }
 
 var (
-	// Map of usernames to user data
-	logins = map[string]user{
-		"admin": {"p@ssw0rd", true}, // NOTE: These are bad passwords!
-		"user1": {"password1", false},
-		"user2": {"password2", false},
-	}
-
-	// Map of certificate fingerprints to sessions
-	sessions = map[string]*session{}
+	// Map of certificate hashes to users
+	users = map[string]*User{}
 )
 
 func main() {
-	var mux gmi.ServeMux
-	mux.HandleFunc("/", welcome)
-	mux.HandleFunc("/login", login)
-	mux.HandleFunc("/login/password", loginPassword)
-	mux.HandleFunc("/profile", profile)
-	mux.HandleFunc("/admin", admin)
-	mux.HandleFunc("/logout", logout)
+	var mux gemini.ServeMux
+	mux.HandleFunc("/", profile)
+	mux.HandleFunc("/username", changeUsername)
 
-	var server gmi.Server
-	if err := server.CertificateStore.Load("/var/lib/gemini/certs"); err != nil {
+	var server gemini.Server
+	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{
+			Subject: pkix.Name{
+				CommonName: hostname,
+			},
+			DNSNames: []string{hostname},
+			Duration: time.Hour,
+		})
+	}
 	server.Register("localhost", &mux)
 
 	if err := server.ListenAndServe(); err != nil {
@@ -52,97 +48,43 @@ func main() {
 	}
 }
 
-func getSession(crt *x509.Certificate) (*session, bool) {
-	fingerprint := gmi.Fingerprint(crt)
-	session, ok := sessions[fingerprint]
-	return session, ok
+func fingerprint(cert *x509.Certificate) string {
+	b := sha512.Sum512(cert.Raw)
+	return string(b[:])
 }
 
-func welcome(w *gmi.ResponseWriter, r *gmi.Request) {
-	fmt.Fprintln(w, "Welcome to this example.")
-	fmt.Fprintln(w, "=> /login Login")
+func profile(w *gemini.ResponseWriter, r *gemini.Request) {
+	if r.Certificate == nil {
+		w.WriteStatus(gemini.StatusCertificateRequired)
+		return
+	}
+	fingerprint := fingerprint(r.Certificate.Leaf)
+	user, ok := users[fingerprint]
+	if !ok {
+		user = &User{}
+		users[fingerprint] = user
+	}
+	fmt.Fprintln(w, "Username:", user.Name)
+	fmt.Fprintln(w, "=> /username Change username")
 }
 
-func login(w *gmi.ResponseWriter, r *gmi.Request) {
-	cert, ok := gmi.Certificate(w, r)
-	if !ok {
-		return
-	}
-	username, ok := gmi.Input(w, r, "Username")
-	if !ok {
-		return
-	}
-	fingerprint := gmi.Fingerprint(cert)
-	sessions[fingerprint] = &session{
-		username: username,
-	}
-	gmi.Redirect(w, r, "/login/password")
-}
-
-func loginPassword(w *gmi.ResponseWriter, r *gmi.Request) {
-	cert, ok := gmi.Certificate(w, r)
-	if !ok {
-		return
-	}
-	session, ok := getSession(cert)
-	if !ok {
-		gmi.CertificateNotAuthorized(w, r)
+func changeUsername(w *gemini.ResponseWriter, r *gemini.Request) {
+	if r.Certificate == nil {
+		w.WriteStatus(gemini.StatusCertificateRequired)
 		return
 	}
 
-	password, ok := gmi.SensitiveInput(w, r, "Password")
-	if !ok {
+	username, err := gemini.QueryUnescape(r.URL.RawQuery)
+	if err != nil || username == "" {
+		w.WriteHeader(gemini.StatusInput, "Username")
 		return
 	}
-	expected := logins[session.username].password
-	if password == expected {
-		session.authorized = true
-		gmi.Redirect(w, r, "/profile")
-	} else {
-		gmi.SensitiveInput(w, r, "Wrong password. Try again")
+	fingerprint := fingerprint(r.Certificate.Leaf)
+	user, ok := users[fingerprint]
+	if !ok {
+		user = &User{}
+		users[fingerprint] = user
 	}
-}
-
-func logout(w *gmi.ResponseWriter, r *gmi.Request) {
-	cert, ok := gmi.Certificate(w, r)
-	if !ok {
-		return
-	}
-	fingerprint := gmi.Fingerprint(cert)
-	delete(sessions, fingerprint)
-	fmt.Fprintln(w, "Successfully logged out.")
-}
-
-func profile(w *gmi.ResponseWriter, r *gmi.Request) {
-	cert, ok := gmi.Certificate(w, r)
-	if !ok {
-		return
-	}
-	session, ok := getSession(cert)
-	if !ok {
-		gmi.CertificateNotAuthorized(w, r)
-		return
-	}
-	user := logins[session.username]
-	fmt.Fprintln(w, "Username:", session.username)
-	fmt.Fprintln(w, "Admin:", user.admin)
-	fmt.Fprintln(w, "=> /logout Logout")
-}
-
-func admin(w *gmi.ResponseWriter, r *gmi.Request) {
-	cert, ok := gmi.Certificate(w, r)
-	if !ok {
-		return
-	}
-	session, ok := getSession(cert)
-	if !ok {
-		gmi.CertificateNotAuthorized(w, r)
-		return
-	}
-	user := logins[session.username]
-	if !user.admin {
-		gmi.CertificateNotAuthorized(w, r)
-		return
-	}
-	fmt.Fprintln(w, "Welcome to the admin portal.")
+	user.Name = username
+	w.WriteHeader(gemini.StatusRedirect, "/")
 }

examples/cert.go

@@ -1,83 +1,43 @@
 // +build ignore
 
+// This example illustrates a certificate generation tool.
+
 package main
 
 import (
-	"bytes"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/pem"
+	"crypto/x509/pkix"
+	"fmt"
 	"log"
 	"os"
 	"time"
 
-	gmi "git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini"
 )
 
 func main() {
-	host := "localhost"
-	duration := 365 * 24 * time.Hour
-	cert, err := gmi.NewCertificate(host, duration)
+	if len(os.Args) < 3 {
+		fmt.Printf("usage: %s [hostname] [duration]\n", os.Args[0])
+		os.Exit(1)
+	}
+	host := os.Args[1]
+	duration, err := time.ParseDuration(os.Args[2])
 	if err != nil {
 		log.Fatal(err)
 	}
-	if err := writeCertificate(host, cert); err != nil {
+	options := gemini.CertificateOptions{
+		Subject: pkix.Name{
+			CommonName: host,
+		},
+		DNSNames: []string{host},
+		Duration: duration,
+	}
+	cert, err := gemini.CreateCertificate(options)
+	if err != nil {
+		log.Fatal(err)
+	}
+	certPath := host + ".crt"
+	keyPath := host + ".key"
+	if err := gemini.WriteCertificate(cert, certPath, keyPath); err != nil {
 		log.Fatal(err)
 	}
 }
-
-// writeCertificate writes the provided certificate and private key
-// to path.crt and path.key respectively.
-func writeCertificate(path string, cert tls.Certificate) error {
-	crt, err := marshalX509Certificate(cert.Leaf.Raw)
-	if err != nil {
-		return err
-	}
-	key, err := marshalPrivateKey(cert.PrivateKey)
-	if err != nil {
-		return err
-	}
-
-	// Write the certificate
-	crtPath := path + ".crt"
-	crtOut, err := os.OpenFile(crtPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
-	}
-	if _, err := crtOut.Write(crt); err != nil {
-		return err
-	}
-
-	// Write the private key
-	keyPath := path + ".key"
-	keyOut, err := os.OpenFile(keyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
-	}
-	if _, err := keyOut.Write(key); err != nil {
-		return err
-	}
-	return nil
-}
-
-// marshalX509Certificate returns a PEM-encoded version of the given raw certificate.
-func marshalX509Certificate(cert []byte) ([]byte, error) {
-	var b bytes.Buffer
-	if err := pem.Encode(&b, &pem.Block{Type: "CERTIFICATE", Bytes: cert}); err != nil {
-		return nil, err
-	}
-	return b.Bytes(), nil
-}
-
-// marshalPrivateKey returns PEM encoded versions of the given certificate and private key.
-func marshalPrivateKey(priv interface{}) ([]byte, error) {
-	var b bytes.Buffer
-	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
-	if err != nil {
-		return nil, err
-	}
-	if err := pem.Encode(&b, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes}); err != nil {
-		return nil, err
-	}
-	return b.Bytes(), nil
-}

examples/client.go

@@ -1,121 +1,42 @@
 // +build ignore
 
+// This example illustrates a Gemini client.
+
 package main
 
 import (
 	"bufio"
-	"crypto/tls"
 	"crypto/x509"
+	"errors"
 	"fmt"
+	"io/ioutil"
+	"log"
 	"net/url"
 	"os"
+	"path/filepath"
 	"time"
 
-	gmi "git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-xdg"
 )
 
 var (
-	scanner = bufio.NewScanner(os.Stdin)
-	client  = &gmi.Client{}
+	hosts   gemini.KnownHostsFile
+	scanner *bufio.Scanner
 )
 
 func init() {
-	// Initialize the client
-	client.KnownHosts.LoadDefault() // Load known hosts
-	client.TrustCertificate = func(hostname string, cert *x509.Certificate, knownHosts *gmi.KnownHosts) error {
-		err := knownHosts.Lookup(hostname, cert)
-		if err != nil {
-			switch err {
-			case gmi.ErrCertificateNotTrusted:
-				// Alert the user that the certificate is not trusted
-				fmt.Printf("Warning: Certificate for %s is not trusted!\n", hostname)
-				fmt.Println("This could indicate a Man-in-the-Middle attack.")
-			case gmi.ErrCertificateUnknown:
-				// Prompt the user to trust the certificate
-				trust := trustCertificate(cert)
-				switch trust {
-				case trustOnce:
-					// Temporarily trust the certificate
-					knownHosts.AddTemporary(hostname, cert)
-					return nil
-				case trustAlways:
-					// Add the certificate to the known hosts file
-					knownHosts.Add(hostname, cert)
-					return nil
-				}
-			}
-		}
-		return err
-	}
-	client.GetCertificate = func(hostname string, store *gmi.CertificateStore) *tls.Certificate {
-		// If the certificate is in the store, return it
-		if cert, err := store.Lookup(hostname); err == nil {
-			return cert
-		}
-		// Otherwise, generate a certificate
-		fmt.Println("Generating client certificate for", hostname)
-		duration := time.Hour
-		cert, err := gmi.NewCertificate(hostname, duration)
-		if err != nil {
-			return nil
-		}
-		// Store and return the certificate
-		store.Add(hostname, cert)
-		return &cert
-	}
-}
-
-// sendRequest sends a request to the given URL.
-func sendRequest(req *gmi.Request) error {
-	resp, err := client.Send(req)
+	// Load known hosts file
+	path := filepath.Join(xdg.DataHome(), "gemini", "known_hosts")
+	err := hosts.Load(path)
 	if err != nil {
-		return err
+		log.Println(err)
 	}
 
-	// TODO: More fine-grained analysis of the status code.
-	switch resp.Status / 10 {
-	case gmi.StatusClassInput:
-		fmt.Printf("%s: ", resp.Meta)
-		scanner.Scan()
-		req.URL.RawQuery = url.QueryEscape(scanner.Text())
-		return sendRequest(req)
-	case gmi.StatusClassSuccess:
-		fmt.Print(string(resp.Body))
-		return nil
-	case gmi.StatusClassRedirect:
-		fmt.Println("Redirecting to", resp.Meta)
-		target, err := url.Parse(resp.Meta)
-		if err != nil {
-			return err
-		}
-		// TODO: Prompt the user if the redirect is to another domain.
-		redirect, err := gmi.NewRequestFromURL(req.URL.ResolveReference(target))
-		if err != nil {
-			return err
-		}
-		return sendRequest(redirect)
-	case gmi.StatusClassTemporaryFailure:
-		return fmt.Errorf("Temporary failure: %s", resp.Meta)
-	case gmi.StatusClassPermanentFailure:
-		return fmt.Errorf("Permanent failure: %s", resp.Meta)
-	case gmi.StatusClassCertificateRequired:
-		// Note that this should not happen unless the server responds with
-		// CertificateRequired even after we send a certificate.
-		// CertificateNotAuthorized and CertificateNotValid are handled here.
-		return fmt.Errorf("Certificate required: %s", resp.Meta)
-	}
-	panic("unreachable")
+	scanner = bufio.NewScanner(os.Stdin)
 }
 
-type trust int
-
-const (
-	trustAbort trust = iota
-	trustOnce
-	trustAlways
-)
-
-const trustPrompt = `The certificate offered by this server is of unknown trust. Its fingerprint is:
+const trustPrompt = `The certificate offered by %s is of unknown trust. Its fingerprint is:
 %s
 
 If you knew the fingerprint to expect in advance, verify that this matches.
@@ -124,45 +45,108 @@ Otherwise, this should be safe to trust.
 [t]rust always; trust [o]nce; [a]bort
 => `
 
-func trustCertificate(cert *x509.Certificate) trust {
-	fmt.Printf(trustPrompt, gmi.Fingerprint(cert))
+func trustCertificate(hostname string, cert *x509.Certificate) error {
+	fingerprint := gemini.NewFingerprint(cert.Raw, cert.NotAfter)
+	knownHost, ok := hosts.Lookup(hostname)
+	if ok && time.Now().Before(knownHost.Expires) {
+		// Check fingerprint
+		if knownHost.Hex == fingerprint.Hex {
+			return nil
+		}
+		return errors.New("error: fingerprint does not match!")
+	}
+
+	fmt.Printf(trustPrompt, hostname, fingerprint.Hex)
 	scanner.Scan()
 	switch scanner.Text() {
 	case "t":
-		return trustAlways
+		hosts.Add(hostname, fingerprint)
+		hosts.Write(hostname, fingerprint)
+		return nil
 	case "o":
-		return trustOnce
+		hosts.Add(hostname, fingerprint)
+		return nil
 	default:
-		return trustAbort
+		return errors.New("certificate not trusted")
 	}
 }
 
+func getInput(prompt string, sensitive bool) (input string, ok bool) {
+	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,
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return resp, err
+	}
+
+	switch resp.Status.Class() {
+	case gemini.StatusClassInput:
+		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.StatusClassRedirect:
+		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://...", os.Args[0])
+		fmt.Printf("usage: %s <url> [host]\n", os.Args[0])
 		os.Exit(1)
 	}
 
-	var host string
-	if len(os.Args) >= 3 {
-		host = os.Args[2]
-	}
-
+	// Do the request
 	url := os.Args[1]
-	var req *gmi.Request
-	var err error
-	if host != "" {
-		req, err = gmi.NewRequestTo(url, host)
-	} else {
-		req, err = gmi.NewRequest(url)
+	req, err := gemini.NewRequest(url)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
 	}
+	if len(os.Args) == 3 {
+		req.Host = os.Args[2]
+	}
+	resp, err := do(req, nil)
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 
-	if err := sendRequest(req); err != nil {
-		fmt.Println(err)
+	// Handle response
+	if resp.Status.Class() == gemini.StatusClassSuccess {
+		defer resp.Body.Close()
+		body, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Print(string(body))
+	} else {
+		fmt.Printf("%d %s: %s\n", resp.Status, resp.Status.Message(), resp.Meta)
 		os.Exit(1)
 	}
 }

examples/html.go

@@ -7,84 +7,77 @@ package main
 import (
 	"fmt"
 	"html"
-	"strings"
+	"io"
+	"os"
 
 	"git.sr.ht/~adnano/go-gemini"
 )
 
 func main() {
-	text := gemini.Text{
-		gemini.LineHeading1("Hello, world!"),
-		gemini.LineText("This is a gemini text document."),
+	hw := HTMLWriter{
+		out: os.Stdout,
 	}
-
-	html := textToHTML(text)
-	fmt.Print(html)
+	gemini.ParseLines(os.Stdin, hw.Handle)
+	hw.Finish()
 }
 
-// textToHTML returns the Gemini text response as HTML.
-func textToHTML(text gemini.Text) string {
-	var b strings.Builder
-	var pre bool
-	var list bool
-	for _, l := range text {
-		if _, ok := l.(gemini.LineListItem); ok {
-			if !list {
-				list = true
-				fmt.Fprint(&b, "<ul>\n")
-			}
-		} else if list {
-			list = false
-			fmt.Fprint(&b, "</ul>\n")
-		}
-		switch l.(type) {
-		case gemini.LineLink:
-			link := l.(gemini.LineLink)
-			url := html.EscapeString(link.URL)
-			name := html.EscapeString(link.Name)
-			if name == "" {
-				name = url
-			}
-			fmt.Fprintf(&b, "<p><a href='%s'>%s</a></p>\n", url, name)
-		case gemini.LinePreformattingToggle:
-			pre = !pre
-			if pre {
-				fmt.Fprint(&b, "<pre>\n")
-			} else {
-				fmt.Fprint(&b, "</pre>\n")
-			}
-		case gemini.LinePreformattedText:
-			text := string(l.(gemini.LinePreformattedText))
-			fmt.Fprintf(&b, "%s\n", html.EscapeString(text))
-		case gemini.LineHeading1:
-			text := string(l.(gemini.LineHeading1))
-			fmt.Fprintf(&b, "<h1>%s</h1>\n", html.EscapeString(text))
-		case gemini.LineHeading2:
-			text := string(l.(gemini.LineHeading2))
-			fmt.Fprintf(&b, "<h2>%s</h2>\n", html.EscapeString(text))
-		case gemini.LineHeading3:
-			text := string(l.(gemini.LineHeading3))
-			fmt.Fprintf(&b, "<h3>%s</h3>\n", html.EscapeString(text))
-		case gemini.LineListItem:
-			text := string(l.(gemini.LineListItem))
-			fmt.Fprintf(&b, "<li>%s</li>\n", html.EscapeString(text))
-		case gemini.LineQuote:
-			text := string(l.(gemini.LineQuote))
-			fmt.Fprintf(&b, "<blockquote>%s</blockquote>\n", html.EscapeString(text))
-		case gemini.LineText:
-			text := string(l.(gemini.LineText))
-			if text == "" {
-				fmt.Fprint(&b, "<br>\n")
-			} else {
-				fmt.Fprintf(&b, "<p>%s</p>\n", html.EscapeString(text))
-			}
-		}
-	}
-	if pre {
-		fmt.Fprint(&b, "</pre>\n")
-	}
-	if list {
-		fmt.Fprint(&b, "</ul>\n")
-	}
-	return b.String()
+type HTMLWriter struct {
+	out  io.Writer
+	pre  bool
+	list bool
+}
+
+func (h *HTMLWriter) Handle(line gemini.Line) {
+	if _, ok := line.(gemini.LineListItem); ok {
+		if !h.list {
+			h.list = true
+			fmt.Fprint(h.out, "<ul>\n")
+		}
+	} else if h.list {
+		h.list = false
+		fmt.Fprint(h.out, "</ul>\n")
+	}
+	switch line := line.(type) {
+	case gemini.LineLink:
+		url := html.EscapeString(line.URL)
+		name := html.EscapeString(line.Name)
+		if name == "" {
+			name = url
+		}
+		fmt.Fprintf(h.out, "<p><a href='%s'>%s</a></p>\n", url, name)
+	case gemini.LinePreformattingToggle:
+		h.pre = !h.pre
+		if h.pre {
+			fmt.Fprint(h.out, "<pre>\n")
+		} else {
+			fmt.Fprint(h.out, "</pre>\n")
+		}
+	case gemini.LinePreformattedText:
+		fmt.Fprintf(h.out, "%s\n", html.EscapeString(string(line)))
+	case gemini.LineHeading1:
+		fmt.Fprintf(h.out, "<h1>%s</h1>\n", html.EscapeString(string(line)))
+	case gemini.LineHeading2:
+		fmt.Fprintf(h.out, "<h2>%s</h2>\n", html.EscapeString(string(line)))
+	case gemini.LineHeading3:
+		fmt.Fprintf(h.out, "<h3>%s</h3>\n", html.EscapeString(string(line)))
+	case gemini.LineListItem:
+		fmt.Fprintf(h.out, "<li>%s</li>\n", html.EscapeString(string(line)))
+	case gemini.LineQuote:
+		fmt.Fprintf(h.out, "<blockquote>%s</blockquote>\n", html.EscapeString(string(line)))
+	case gemini.LineText:
+		if line == "" {
+			fmt.Fprint(h.out, "<br>\n")
+		} else {
+			fmt.Fprintf(h.out, "<p>%s</p>\n", html.EscapeString(string(line)))
+		}
+	}
+}
+
+func (h *HTMLWriter) Finish() {
+	if h.pre {
+		fmt.Fprint(h.out, "</pre>\n")
+	}
+	if h.list {
+		fmt.Fprint(h.out, "</ul>\n")
+	}
 }

examples/server.go

@@ -1,112 +1,40 @@
 // +build ignore
 
+// This example illustrates a Gemini server.
+
 package main
 
 import (
-	"bytes"
 	"crypto/tls"
-	"crypto/x509"
-	"encoding/pem"
+	"crypto/x509/pkix"
 	"log"
-	"os"
 	"time"
 
-	gmi "git.sr.ht/~adnano/go-gemini"
+	"git.sr.ht/~adnano/go-gemini"
 )
 
 func main() {
-	var server gmi.Server
-	if err := server.CertificateStore.Load("/var/lib/gemini/certs"); err != nil {
+	var server gemini.Server
+	server.ReadTimeout = 30 * time.Second
+	server.WriteTimeout = 1 * time.Minute
+	if err := server.Certificates.Load("/var/lib/gemini/certs"); err != nil {
 		log.Fatal(err)
 	}
-	server.GetCertificate = func(hostname string, store *gmi.CertificateStore) *tls.Certificate {
-		cert, err := store.Lookup(hostname)
-		if err != nil {
-			switch err {
-			case gmi.ErrCertificateExpired:
-				// Generate a new certificate if the current one is expired.
-				log.Print("Old certificate expired, creating new one")
-				fallthrough
-			case gmi.ErrCertificateUnknown:
-				// Generate a certificate if one does not exist.
-				cert, err := gmi.NewCertificate(hostname, time.Minute)
-				if err != nil {
-					// Failed to generate new certificate, abort
-					return nil
-				}
-				// Store and return the new certificate
-				err = writeCertificate("/var/lib/gemini/certs/"+hostname, cert)
-				if err != nil {
-					return nil
-				}
-				store.Add(hostname, cert)
-				return &cert
-			}
-		}
-		return cert
+	server.CreateCertificate = func(hostname string) (tls.Certificate, error) {
+		return gemini.CreateCertificate(gemini.CertificateOptions{
+			Subject: pkix.Name{
+				CommonName: hostname,
+			},
+			DNSNames: []string{hostname},
+			Duration: 365 * 24 * time.Hour,
+		})
 	}
 
-	var mux gmi.ServeMux
-	mux.Handle("/", gmi.FileServer(gmi.Dir("/var/www")))
+	var mux gemini.ServeMux
+	mux.Handle("/", gemini.FileServer(gemini.Dir("/var/www")))
 
 	server.Register("localhost", &mux)
 	if err := server.ListenAndServe(); err != nil {
 		log.Fatal(err)
 	}
 }
-
-// writeCertificate writes the provided certificate and private key
-// to path.crt and path.key respectively.
-func writeCertificate(path string, cert tls.Certificate) error {
-	crt, err := marshalX509Certificate(cert.Leaf.Raw)
-	if err != nil {
-		return err
-	}
-	key, err := marshalPrivateKey(cert.PrivateKey)
-	if err != nil {
-		return err
-	}
-
-	// Write the certificate
-	crtPath := path + ".crt"
-	crtOut, err := os.OpenFile(crtPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
-	}
-	if _, err := crtOut.Write(crt); err != nil {
-		return err
-	}
-
-	// Write the private key
-	keyPath := path + ".key"
-	keyOut, err := os.OpenFile(keyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
-	}
-	if _, err := keyOut.Write(key); err != nil {
-		return err
-	}
-	return nil
-}
-
-// marshalX509Certificate returns a PEM-encoded version of the given raw certificate.
-func marshalX509Certificate(cert []byte) ([]byte, error) {
-	var b bytes.Buffer
-	if err := pem.Encode(&b, &pem.Block{Type: "CERTIFICATE", Bytes: cert}); err != nil {
-		return nil, err
-	}
-	return b.Bytes(), nil
-}
-
-// marshalPrivateKey returns PEM encoded versions of the given certificate and private key.
-func marshalPrivateKey(priv interface{}) ([]byte, error) {
-	var b bytes.Buffer
-	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
-	if err != nil {
-		return nil, err
-	}
-	if err := pem.Encode(&b, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes}); err != nil {
-		return nil, err
-	}
-	return b.Bytes(), nil
-}

examples/stream.go

@@ -0,0 +1,44 @@
+// +build ignore
+
+// This example illustrates a streaming Gemini server.
+
+package main
+
+import (
+	"crypto/tls"
+	"crypto/x509/pkix"
+	"fmt"
+	"log"
+	"time"
+
+	"git.sr.ht/~adnano/go-gemini"
+)
+
+func main() {
+	var server gemini.Server
+	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{
+			Subject: pkix.Name{
+				CommonName: hostname,
+			},
+			DNSNames: []string{hostname},
+			Duration: 365 * 24 * time.Hour,
+		})
+	}
+
+	server.RegisterFunc("localhost", stream)
+	if err := server.ListenAndServe(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func stream(w *gemini.ResponseWriter, r *gemini.Request) {
+	for {
+		fmt.Fprintln(w, time.Now().UTC())
+		w.Flush()
+		time.Sleep(time.Second)
+	}
+}

fs.go

@@ -5,7 +5,6 @@ import (
 	"mime"
 	"os"
 	"path"
-	"path/filepath"
 )
 
 func init() {
@@ -25,16 +24,16 @@ type fsHandler struct {
 }
 
 func (fsh fsHandler) Respond(w *ResponseWriter, r *Request) {
-	path := path.Clean(r.URL.Path)
-	f, err := fsh.Open(path)
+	p := path.Clean(r.URL.Path)
+	f, err := fsh.Open(p)
 	if err != nil {
 		w.WriteStatus(StatusNotFound)
 		return
 	}
 	// Detect mimetype
-	ext := filepath.Ext(path)
+	ext := path.Ext(p)
 	mimetype := mime.TypeByExtension(ext)
-	w.SetMimetype(mimetype)
+	w.SetMediaType(mimetype)
 	// Copy file to response writer
 	io.Copy(w, f)
 }
@@ -71,9 +70,9 @@ func ServeFile(w *ResponseWriter, fs FS, name string) {
 		return
 	}
 	// Detect mimetype
-	ext := filepath.Ext(name)
+	ext := path.Ext(name)
 	mimetype := mime.TypeByExtension(ext)
-	w.SetMimetype(mimetype)
+	w.SetMediaType(mimetype)
 	// Copy file to response writer
 	io.Copy(w, f)
 }
@@ -97,9 +96,9 @@ func openFile(p string) (File, error) {
 			if stat.Mode().IsRegular() {
 				return f, nil
 			}
-			return nil, ErrNotAFile
+			return nil, os.ErrNotExist
 		} else if !stat.Mode().IsRegular() {
-			return nil, ErrNotAFile
+			return nil, os.ErrNotExist
 		}
 	}
 	return f, nil

gemini.go

@@ -1,143 +1,64 @@
+/*
+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 (
-	"crypto/tls"
-	"crypto/x509"
 	"errors"
-	"sync"
-	"time"
 )
 
-// Status codes.
-type Status int
-
-const (
-	StatusInput                    Status = 10
-	StatusSensitiveInput           Status = 11
-	StatusSuccess                  Status = 20
-	StatusRedirect                 Status = 30
-	StatusRedirectPermanent        Status = 31
-	StatusTemporaryFailure         Status = 40
-	StatusServerUnavailable        Status = 41
-	StatusCGIError                 Status = 42
-	StatusProxyError               Status = 43
-	StatusSlowDown                 Status = 44
-	StatusPermanentFailure         Status = 50
-	StatusNotFound                 Status = 51
-	StatusGone                     Status = 52
-	StatusProxyRequestRefused      Status = 53
-	StatusBadRequest               Status = 59
-	StatusCertificateRequired      Status = 60
-	StatusCertificateNotAuthorized Status = 61
-	StatusCertificateNotValid      Status = 62
-)
-
-// Class returns the status class for this status code.
-func (s Status) Class() StatusClass {
-	return StatusClass(s / 10)
-}
-
-// StatusMessage returns the status message corresponding to the provided
-// status code.
-// StatusMessage returns an empty string for input, successs, and redirect
-// status codes.
-func (s Status) Message() string {
-	switch s {
-	case StatusTemporaryFailure:
-		return "TemporaryFailure"
-	case StatusServerUnavailable:
-		return "Server unavailable"
-	case StatusCGIError:
-		return "CGI error"
-	case StatusProxyError:
-		return "Proxy error"
-	case StatusSlowDown:
-		return "Slow down"
-	case StatusPermanentFailure:
-		return "PermanentFailure"
-	case StatusNotFound:
-		return "Not found"
-	case StatusGone:
-		return "Gone"
-	case StatusProxyRequestRefused:
-		return "Proxy request refused"
-	case StatusBadRequest:
-		return "Bad request"
-	case StatusCertificateRequired:
-		return "Certificate required"
-	case StatusCertificateNotAuthorized:
-		return "Certificate not authorized"
-	case StatusCertificateNotValid:
-		return "Certificate not valid"
-	}
-	return ""
-}
-
-// Status code categories.
-type StatusClass int
-
-const (
-	StatusClassInput               StatusClass = 1
-	StatusClassSuccess             StatusClass = 2
-	StatusClassRedirect            StatusClass = 3
-	StatusClassTemporaryFailure    StatusClass = 4
-	StatusClassPermanentFailure    StatusClass = 5
-	StatusClassCertificateRequired StatusClass = 6
-)
+var crlf = []byte("\r\n")
 
 // Errors.
 var (
-	ErrInvalidURL            = errors.New("gemini: invalid URL")
-	ErrInvalidResponse       = errors.New("gemini: invalid response")
-	ErrCertificateUnknown    = errors.New("gemini: unknown certificate")
-	ErrCertificateExpired    = errors.New("gemini: certificate expired")
-	ErrCertificateNotTrusted = errors.New("gemini: certificate is not trusted")
-	ErrNotAFile              = errors.New("gemini: not a file")
-	ErrBodyNotAllowed        = errors.New("gemini: response status code does not allow for body")
+	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")
 )
-
-// DefaultClient is the default client. It is used by Send.
-//
-// On the first request, DefaultClient will load the default list of known hosts.
-var DefaultClient Client
-
-var (
-	crlf = []byte("\r\n")
-)
-
-func init() {
-	DefaultClient.TrustCertificate = func(hostname string, cert *x509.Certificate, knownHosts *KnownHosts) error {
-		// Load the hosts only once. This is so that the hosts don't have to be loaded
-		// for those using their own clients.
-		setupDefaultClientOnce.Do(setupDefaultClient)
-		return knownHosts.Lookup(hostname, cert)
-	}
-	DefaultClient.GetCertificate = func(hostname string, store *CertificateStore) *tls.Certificate {
-		// If the certificate is in the store, return it
-		if cert, err := store.Lookup(hostname); err == nil {
-			return cert
-		}
-		// Otherwise, generate a certificate
-		duration := time.Hour
-		cert, err := NewCertificate(hostname, duration)
-		if err != nil {
-			return nil
-		}
-		// Store and return the certificate
-		store.Add(hostname, cert)
-		return &cert
-	}
-}
-
-var setupDefaultClientOnce sync.Once
-
-func setupDefaultClient() {
-	DefaultClient.KnownHosts.LoadDefault()
-}
-
-// Send sends a Gemini request and returns a Gemini response.
-//
-// Send is a wrapper around DefaultClient.Send.
-func Send(req *Request) (*Response, error) {
-	return DefaultClient.Send(req)
-}

mux.go

@@ -0,0 +1,210 @@
+package gemini
+
+import (
+	"net/url"
+	"path"
+	"sort"
+	"strings"
+	"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
+// most closely matches the URL.
+//
+// Patterns name fixed, rooted paths, like "/favicon.ico",
+// or rooted subtrees, like "/images/" (note the trailing slash).
+// Longer patterns take precedence over shorter ones, so that
+// if there are handlers registered for both "/images/"
+// and "/images/thumbnails/", the latter handler will be
+// called for paths beginning "/images/thumbnails/" and the
+// former will receive requests for any other paths in the
+// "/images/" subtree.
+//
+// Note that since a pattern ending in a slash names a rooted subtree,
+// the pattern "/" matches all paths not matched by other registered
+// patterns, not just the URL with Path == "/".
+//
+// 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
+// be overridden with a separate registration for the path without
+// the trailing slash. For example, registering "/images/" causes ServeMux
+// to redirect a request for "/images" to "/images/", unless "/images" has
+// been registered separately.
+//
+// ServeMux also takes care of sanitizing the URL request path and
+// redirecting any request containing . or .. elements or repeated slashes
+// to an equivalent, cleaner URL.
+type ServeMux struct {
+	mu sync.RWMutex
+	m  map[string]muxEntry
+	es []muxEntry // slice of entries sorted from longest to shortest.
+}
+
+type muxEntry struct {
+	r       Responder
+	pattern string
+}
+
+// cleanPath returns the canonical path for p, eliminating . and .. elements.
+func cleanPath(p string) string {
+	if p == "" {
+		return "/"
+	}
+	if p[0] != '/' {
+		p = "/" + p
+	}
+	np := path.Clean(p)
+	// path.Clean removes trailing slash except for root;
+	// put the trailing slash back if necessary.
+	if p[len(p)-1] == '/' && np != "/" {
+		// Fast path for common case of p being the string we want:
+		if len(p) == len(np)+1 && strings.HasPrefix(p, np) {
+			np = p
+		} else {
+			np += "/"
+		}
+	}
+	return np
+}
+
+// Find a handler on a handler map given a path string.
+// Most-specific (longest) pattern wins.
+func (mux *ServeMux) match(path string) Responder {
+	// Check for exact match first.
+	v, ok := mux.m[path]
+	if ok {
+		return v.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) {
+			return e.r
+		}
+	}
+	return nil
+}
+
+// redirectToPathSlash determines if the given path needs appending "/" to it.
+// 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) {
+	mux.mu.RLock()
+	shouldRedirect := mux.shouldRedirectRLocked(path)
+	mux.mu.RUnlock()
+	if !shouldRedirect {
+		return u, false
+	}
+	path = path + "/"
+	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 {
+	if _, exist := mux.m[path]; exist {
+		return false
+	}
+
+	n := len(path)
+	if n == 0 {
+		return false
+	}
+	if _, exist := mux.m[path+"/"]; exist {
+		return path[n-1] != '/'
+	}
+
+	return false
+}
+
+// Respond dispatches the request to the responder whose
+// pattern most closely matches the request URL.
+func (mux *ServeMux) Respond(w *ResponseWriter, r *Request) {
+	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 {
+		w.WriteHeader(StatusRedirect, u.String())
+		return
+	}
+
+	if path != r.URL.Path {
+		u := *r.URL
+		u.Path = path
+		w.WriteHeader(StatusRedirect, u.String())
+		return
+	}
+
+	mux.mu.RLock()
+	defer mux.mu.RUnlock()
+
+	resp := mux.match(path)
+	if resp == nil {
+		w.WriteStatus(StatusNotFound)
+		return
+	}
+	resp.Respond(w, r)
+}
+
+// Handle registers the responder for the given pattern.
+// If a responder already exists for pattern, Handle panics.
+func (mux *ServeMux) Handle(pattern string, responder Responder) {
+	mux.mu.Lock()
+	defer mux.mu.Unlock()
+
+	if pattern == "" {
+		panic("gemini: invalid pattern")
+	}
+	if responder == nil {
+		panic("gemini: nil responder")
+	}
+	if _, exist := mux.m[pattern]; exist {
+		panic("gemini: multiple registrations for " + pattern)
+	}
+
+	if mux.m == nil {
+		mux.m = make(map[string]muxEntry)
+	}
+	e := muxEntry{responder, pattern}
+	mux.m[pattern] = e
+	if pattern[len(pattern)-1] == '/' {
+		mux.es = appendSorted(mux.es, e)
+	}
+}
+
+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)
+	})
+	if i == n {
+		return append(es, e)
+	}
+	// we now know that i points at where we want to insert
+	es = append(es, muxEntry{}) // try to grow the slice in place, any entry works.
+	copy(es[i+1:], es[i:])      // move shorter entries down
+	es[i] = e
+	return es
+}
+
+// HandleFunc registers the responder function for the given pattern.
+func (mux *ServeMux) HandleFunc(pattern string, responder func(*ResponseWriter, *Request)) {
+	if responder == nil {
+		panic("gemini: nil responder")
+	}
+	mux.Handle(pattern, ResponderFunc(responder))
+}

query.go

@@ -0,0 +1,18 @@
+package gemini
+
+import (
+	"net/url"
+	"strings"
+)
+
+// 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.
+func QueryEscape(query string) string {
+	return strings.ReplaceAll(url.PathEscape(query), "+", "%2B")
+}
+
+// QueryUnescape is identical to url.PathUnescape.
+func QueryUnescape(query string) (string, error) {
+	return url.PathUnescape(query)
+}

request.go

@@ -2,7 +2,9 @@ package gemini
 
 import (
 	"bufio"
+	"context"
 	"crypto/tls"
+	"io"
 	"net"
 	"net/url"
 )
@@ -14,32 +16,32 @@ type Request struct {
 
 	// For client requests, Host specifies the host on which the URL is sought.
 	// Host must contain a port.
+	//
 	// This field is ignored by the server.
 	Host string
 
 	// Certificate specifies the TLS certificate to use for the request.
 	// Request certificates take precedence over client certificates.
-	// This field is ignored by the 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
 	// 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
-}
 
-// hostname returns the host without the port.
-func hostname(host string) string {
-	hostname, _, err := net.SplitHostPort(host)
-	if err != nil {
-		return host
-	}
-	return hostname
+	// Context specifies the context to use for client requests.
+	// If Context is nil, the background context will be used.
+	Context context.Context
 }
 
 // NewRequest returns a new request. The host is inferred from the URL.
@@ -48,40 +50,58 @@ func NewRequest(rawurl string) (*Request, error) {
 	if err != nil {
 		return nil, err
 	}
-	return NewRequestFromURL(u)
+	return NewRequestFromURL(u), nil
 }
 
 // NewRequestFromURL returns a new request for the given URL.
 // The host is inferred from the URL.
-func NewRequestFromURL(url *url.URL) (*Request, error) {
-	// If there is no port, use the default port of 1965
+//
+// Callers should be careful that the URL query is properly escaped.
+// See the documentation for QueryEscape for more information.
+func NewRequestFromURL(url *url.URL) *Request {
 	host := url.Host
 	if url.Port() == "" {
 		host += ":1965"
 	}
-
 	return &Request{
-		Host: host,
 		URL:  url,
-	}, nil
+		Host: host,
+	}
 }
 
-// NewRequestTo returns a new request for the provided URL to the provided host.
-// The host must contain a port.
-func NewRequestTo(rawurl, host string) (*Request, error) {
+// ReadRequest reads a Gemini request from the provided io.Reader
+func ReadRequest(r io.Reader) (*Request, error) {
+	// Read URL
+	br := bufio.NewReader(r)
+	rawurl, err := br.ReadString('\r')
+	if err != nil {
+		return nil, err
+	}
+	// Read terminating line feed
+	if b, err := br.ReadByte(); err != nil {
+		return nil, err
+	} 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{
-		Host: host,
-		URL:  u,
-	}, nil
+	if u.User != nil {
+		// User is not allowed
+		return nil, ErrInvalidURL
+	}
+	return &Request{URL: u}, nil
 }
 
-// write writes the Gemini request to the provided buffered writer.
-func (r *Request) write(w *bufio.Writer) error {
+// Write writes the Gemini request to the provided buffered writer.
+func (r *Request) Write(w *bufio.Writer) error {
 	url := r.URL.String()
 	// User is invalid
 	if r.URL.User != nil || len(url) > 1024 {

response.go

@@ -3,13 +3,13 @@ package gemini
 import (
 	"bufio"
 	"crypto/tls"
-	"io/ioutil"
+	"io"
 	"strconv"
 )
 
 // Response is a Gemini response.
 type Response struct {
-	// Status represents the response status.
+	// Status contains the response status code.
 	Status Status
 
 	// Meta contains more information related to the response status.
@@ -18,24 +18,27 @@ type Response struct {
 	// Meta should not be longer than 1024 bytes.
 	Meta string
 
-	// Body contains the response body.
-	Body []byte
+	// Body contains the response body for successful responses.
+	Body io.ReadCloser
 
 	// TLS contains information about the TLS connection on which the response
 	// was received.
 	TLS tls.ConnectionState
 }
 
-// read reads a Gemini response from the provided buffered reader.
-func (resp *Response) read(r *bufio.Reader) error {
+// ReadResponse reads a Gemini response from the provided io.ReadCloser.
+func ReadResponse(rc io.ReadCloser) (*Response, error) {
+	resp := &Response{}
+	br := bufio.NewReader(rc)
+
 	// Read the status
 	statusB := make([]byte, 2)
-	if _, err := r.Read(statusB); err != nil {
-		return err
+	if _, err := br.Read(statusB); err != nil {
+		return nil, err
 	}
 	status, err := strconv.Atoi(string(statusB))
 	if err != nil {
-		return err
+		return nil, err
 	}
 	resp.Status = Status(status)
 
@@ -43,43 +46,69 @@ func (resp *Response) read(r *bufio.Reader) error {
 	const minStatus, maxStatus = 1, 6
 	statusClass := resp.Status.Class()
 	if statusClass < minStatus || statusClass > maxStatus {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
 
 	// Read one space
-	if b, err := r.ReadByte(); err != nil {
-		return err
+	if b, err := br.ReadByte(); err != nil {
+		return nil, err
 	} else if b != ' ' {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
 
 	// Read the meta
-	meta, err := r.ReadString('\r')
+	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 statusClass == StatusClassSuccess && meta == "" {
+		meta = "text/gemini; charset=utf-8"
 	}
 	resp.Meta = meta
 
 	// Read terminating newline
-	if b, err := r.ReadByte(); err != nil {
-		return err
+	if b, err := br.ReadByte(); err != nil {
+		return nil, err
 	} else if b != '\n' {
-		return ErrInvalidResponse
+		return nil, ErrInvalidResponse
 	}
 
-	// Read response body
 	if resp.Status.Class() == StatusClassSuccess {
-		var err error
-		resp.Body, err = ioutil.ReadAll(r)
-		if err != nil {
-			return err
-		}
+		resp.Body = newReadCloserBody(br, rc)
 	}
-	return nil
+	return resp, nil
+}
+
+type readCloserBody struct {
+	br *bufio.Reader // used until empty
+	io.ReadCloser
+}
+
+func newReadCloserBody(br *bufio.Reader, rc io.ReadCloser) io.ReadCloser {
+	body := &readCloserBody{ReadCloser: rc}
+	if br.Buffered() != 0 {
+		body.br = br
+	}
+	return body
+}
+
+func (b *readCloserBody) 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)
 }

server.go

@@ -3,15 +3,12 @@ package gemini
 import (
 	"bufio"
 	"crypto/tls"
-	"crypto/x509"
+	"errors"
+	"io"
 	"log"
 	"net"
-	"net/url"
-	"path"
-	"sort"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 )
 
@@ -21,28 +18,40 @@ type Server struct {
 	// If Addr is empty, the server will listen on the address ":1965".
 	Addr string
 
-	// CertificateStore contains the certificates used by the server.
-	CertificateStore CertificateStore
+	// ReadTimeout is the maximum duration for reading a request.
+	ReadTimeout time.Duration
 
-	// GetCertificate, if not nil, will be called to retrieve the certificate
-	// to use for a given hostname.
-	// If the certificate is nil, the connection will be aborted.
-	GetCertificate func(hostname string, store *CertificateStore) *tls.Certificate
+	// WriteTimeout is the maximum duration before timing out
+	// writes of the response.
+	WriteTimeout time.Duration
+
+	// Certificates contains the certificates used by the server.
+	Certificates CertificateDir
+
+	// CreateCertificate, if not nil, will be called to create a new certificate
+	// if the current one is expired or missing.
+	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
 
 	// registered responders
 	responders map[responderKey]Responder
+	hosts      map[string]bool
 }
 
 type responderKey struct {
 	scheme   string
 	hostname string
-	wildcard bool
 }
 
 // Register registers a responder for the given pattern.
-// Patterns must be in the form of scheme://hostname (e.g. gemini://example.com).
-// If no scheme is specified, a default scheme of gemini:// is assumed.
-// Wildcard patterns are supported (e.g. *.example.com).
+//
+// Patterns must be in the form of "hostname" or "scheme://hostname".
+// If no scheme is specified, a scheme of "gemini://" is implied.
+// Wildcard patterns are supported (e.g. "*.example.com").
 func (s *Server) Register(pattern string, responder Responder) {
 	if pattern == "" {
 		panic("gemini: invalid pattern")
@@ -52,6 +61,7 @@ func (s *Server) Register(pattern string, responder Responder) {
 	}
 	if s.responders == nil {
 		s.responders = map[responderKey]Responder{}
+		s.hosts = map[string]bool{}
 	}
 
 	split := strings.SplitN(pattern, "://", 2)
@@ -63,13 +73,12 @@ func (s *Server) Register(pattern string, responder Responder) {
 		key.scheme = "gemini"
 		key.hostname = split[0]
 	}
-	split = strings.SplitN(key.hostname, ".", 2)
-	if len(split) == 2 && split[0] == "*" {
-		key.hostname = split[1]
-		key.wildcard = true
-	}
 
+	if _, ok := s.responders[key]; ok {
+		panic("gemini: multiple registrations for " + pattern)
+	}
 	s.responders[key] = responder
+	s.hosts[key.hostname] = true
 }
 
 // RegisterFunc registers a responder function for the given pattern.
@@ -90,18 +99,11 @@ func (s *Server) ListenAndServe() error {
 	}
 	defer ln.Close()
 
-	config := &tls.Config{
-		ClientAuth: tls.RequestClientCert,
-		MinVersion: tls.VersionTLS12,
-		GetCertificate: func(h *tls.ClientHelloInfo) (*tls.Certificate, error) {
-			if s.GetCertificate != nil {
-				return s.GetCertificate(h.ServerName, &s.CertificateStore), nil
-			}
-			return s.CertificateStore.Lookup(h.ServerName)
-		},
-	}
-	tlsListener := tls.NewListener(ln, config)
-	return s.Serve(tlsListener)
+	return s.Serve(tls.NewListener(ln, &tls.Config{
+		ClientAuth:     tls.RequestClientCert,
+		MinVersion:     tls.VersionTLS12,
+		GetCertificate: s.getCertificate,
+	}))
 }
 
 // Serve listens for requests on the provided listener.
@@ -121,7 +123,7 @@ func (s *Server) Serve(l net.Listener) error {
 				if max := 1 * time.Second; tempDelay > max {
 					tempDelay = max
 				}
-				log.Printf("gemini: Accept error: %v; retrying in %v", err, tempDelay)
+				s.logf("gemini: Accept error: %v; retrying in %v", err, tempDelay)
 				time.Sleep(tempDelay)
 				continue
 			}
@@ -135,74 +137,113 @@ func (s *Server) Serve(l net.Listener) error {
 	}
 }
 
+func (s *Server) getCertificate(h *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	cert, err := s.getCertificateFor(h.ServerName)
+	if err != nil {
+		// Try wildcard
+		wildcard := strings.SplitN(h.ServerName, ".", 2)
+		if len(wildcard) == 2 {
+			cert, err = s.getCertificateFor("*." + wildcard[1])
+		}
+	}
+	return cert, err
+}
+
+func (s *Server) getCertificateFor(hostname string) (*tls.Certificate, error) {
+	if _, ok := s.hosts[hostname]; !ok {
+		return nil, errors.New("hostname not registered")
+	}
+
+	// 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.
 func (s *Server) respond(conn net.Conn) {
-	r := bufio.NewReader(conn)
-	w := newResponseWriter(conn)
-	// Read requested URL
-	rawurl, err := r.ReadString('\r')
+	defer conn.Close()
+	if d := s.ReadTimeout; d != 0 {
+		conn.SetReadDeadline(time.Now().Add(d))
+	}
+	if d := s.WriteTimeout; d != 0 {
+		conn.SetWriteDeadline(time.Now().Add(d))
+	}
+
+	w := NewResponseWriter(conn)
+	defer w.b.Flush()
+
+	req, err := ReadRequest(conn)
 	if err != nil {
-		return
-	}
-	// Read terminating line feed
-	if b, err := r.ReadByte(); err != nil {
-		return
-	} else if b != '\n' {
-		w.WriteHeader(StatusBadRequest, "Bad request")
-	}
-	// Trim carriage return
-	rawurl = rawurl[:len(rawurl)-1]
-	// Ensure URL is valid
-	if len(rawurl) > 1024 {
-		w.WriteHeader(StatusBadRequest, "Bad request")
-	} 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.WriteHeader(StatusBadRequest, "Bad request")
+		w.WriteStatus(StatusBadRequest)
 	} else {
-		// If no scheme is specified, assume a default scheme of gemini://
-		if url.Scheme == "" {
-			url.Scheme = "gemini"
-		}
-		req := &Request{
-			URL:        url,
-			RemoteAddr: conn.RemoteAddr(),
-			TLS:        conn.(*tls.Conn).ConnectionState(),
-		}
-		resp := s.responder(req)
-		if resp != nil {
-			resp.Respond(w, req)
-		} else {
-			w.WriteStatus(StatusNotFound)
+		// Store information about the TLS connection
+		if tlsConn, ok := conn.(*tls.Conn); ok {
+			req.TLS = tlsConn.ConnectionState()
+			if len(req.TLS.PeerCertificates) > 0 {
+				peerCert := req.TLS.PeerCertificates[0]
+				// Store the TLS certificate
+				req.Certificate = &tls.Certificate{
+					Certificate: [][]byte{peerCert.Raw},
+					Leaf:        peerCert,
+				}
+			}
 		}
 	}
-	w.b.Flush()
-	conn.Close()
+
+	resp := s.responder(req)
+	if resp != nil {
+		resp.Respond(w, req)
+	} else {
+		w.WriteStatus(StatusNotFound)
+	}
 }
 
 func (s *Server) responder(r *Request) Responder {
-	if h, ok := s.responders[responderKey{r.URL.Scheme, r.URL.Hostname(), false}]; ok {
+	if h, ok := s.responders[responderKey{r.URL.Scheme, r.URL.Hostname()}]; ok {
 		return h
 	}
 	wildcard := strings.SplitN(r.URL.Hostname(), ".", 2)
 	if len(wildcard) == 2 {
-		if h, ok := s.responders[responderKey{r.URL.Scheme, wildcard[1], true}]; ok {
+		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
-	mimetype    string
+	mediatype   string
 }
 
-func newResponseWriter(conn net.Conn) *ResponseWriter {
+// NewResponseWriter returns a ResponseWriter that uses the provided io.Writer.
+func NewResponseWriter(w io.Writer) *ResponseWriter {
 	return &ResponseWriter{
-		b: bufio.NewWriter(conn),
+		b: bufio.NewWriter(w),
 	}
 }
 
@@ -230,32 +271,31 @@ func (w *ResponseWriter) WriteHeader(status Status, meta string) {
 }
 
 // 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())
 }
 
-// SetMimetype sets the mimetype that will be written for a successful response.
-// The provided mimetype will only be used if Write is called without calling
-// WriteHeader.
+// 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) SetMimetype(mimetype string) {
-	w.mimetype = mimetype
+func (w *ResponseWriter) SetMediaType(mediatype string) {
+	w.mediatype = mediatype
 }
 
-// Write writes the response body.
+// Write writes data to the connection as part of the response body.
 // If the response status does not allow for a response body, Write returns
 // ErrBodyNotAllowed.
 //
-// If WriteHeader has not yet been called, Write calls
-// WriteHeader(StatusSuccess, mimetype) where mimetype is the mimetype set in
-// SetMimetype. If no mimetype is set, a default of "text/gemini" will be used.
+// 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 {
-		mimetype := w.mimetype
-		if mimetype == "" {
-			mimetype = "text/gemini"
+		mediatype := w.mediatype
+		if mediatype == "" {
+			mediatype = "text/gemini"
 		}
-		w.WriteHeader(StatusSuccess, mimetype)
+		w.WriteHeader(StatusSuccess, mediatype)
 	}
 	if !w.bodyAllowed {
 		return 0, ErrBodyNotAllowed
@@ -263,256 +303,20 @@ func (w *ResponseWriter) Write(b []byte) (int, error) {
 	return w.b.Write(b)
 }
 
+// Flush writes any buffered data to the underlying io.Writer.
+func (w *ResponseWriter) Flush() error {
+	return w.b.Flush()
+}
+
 // A Responder responds to a Gemini request.
 type Responder interface {
 	// Respond accepts a Request and constructs a Response.
 	Respond(*ResponseWriter, *Request)
 }
 
-// Input returns the request query.
-// If no input is provided, it responds with StatusInput.
-func Input(w *ResponseWriter, r *Request, prompt string) (string, bool) {
-	if r.URL.ForceQuery || r.URL.RawQuery != "" {
-		return r.URL.RawQuery, true
-	}
-	w.WriteHeader(StatusInput, prompt)
-	return "", false
-}
-
-// SensitiveInput returns the request query.
-// If no input is provided, it responds with StatusSensitiveInput.
-func SensitiveInput(w *ResponseWriter, r *Request, prompt string) (string, bool) {
-	if r.URL.ForceQuery || r.URL.RawQuery != "" {
-		return r.URL.RawQuery, true
-	}
-	w.WriteHeader(StatusSensitiveInput, prompt)
-	return "", false
-}
-
-// Redirect replies to the request with a redirect to the given URL.
-func Redirect(w *ResponseWriter, url string) {
-	w.WriteHeader(StatusRedirect, url)
-}
-
-// PermanentRedirect replies to the request with a permanent redirect to the given URL.
-func PermanentRedirect(w *ResponseWriter, url string) {
-	w.WriteHeader(StatusRedirectPermanent, url)
-}
-
-// Certificate returns the request certificate. If one is not provided,
-// it returns nil and responds with StatusCertificateRequired.
-func Certificate(w *ResponseWriter, r *Request) (*x509.Certificate, bool) {
-	if len(r.TLS.PeerCertificates) == 0 {
-		w.WriteStatus(StatusCertificateRequired)
-		return nil, false
-	}
-	return r.TLS.PeerCertificates[0], true
-}
-
 // 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)
 }
-
-// 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
-// most closely matches the URL.
-//
-// Patterns name fixed, rooted paths, like "/favicon.ico",
-// or rooted subtrees, like "/images/" (note the trailing slash).
-// Longer patterns take precedence over shorter ones, so that
-// if there are handlers registered for both "/images/"
-// and "/images/thumbnails/", the latter handler will be
-// called for paths beginning "/images/thumbnails/" and the
-// former will receive requests for any other paths in the
-// "/images/" subtree.
-//
-// Note that since a pattern ending in a slash names a rooted subtree,
-// the pattern "/" matches all paths not matched by other registered
-// patterns, not just the URL with Path == "/".
-//
-// 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
-// be overridden with a separate registration for the path without
-// the trailing slash. For example, registering "/images/" causes ServeMux
-// to redirect a request for "/images" to "/images/", unless "/images" has
-// been registered separately.
-//
-// ServeMux also takes care of sanitizing the URL request path and
-// redirecting any request containing . or .. elements or repeated slashes
-// to an equivalent, cleaner URL.
-type ServeMux struct {
-	mu sync.RWMutex
-	m  map[string]muxEntry
-	es []muxEntry // slice of entries sorted from longest to shortest.
-}
-
-type muxEntry struct {
-	r       Responder
-	pattern string
-}
-
-// cleanPath returns the canonical path for p, eliminating . and .. elements.
-func cleanPath(p string) string {
-	if p == "" {
-		return "/"
-	}
-	if p[0] != '/' {
-		p = "/" + p
-	}
-	np := path.Clean(p)
-	// path.Clean removes trailing slash except for root;
-	// put the trailing slash back if necessary.
-	if p[len(p)-1] == '/' && np != "/" {
-		// Fast path for common case of p being the string we want:
-		if len(p) == len(np)+1 && strings.HasPrefix(p, np) {
-			np = p
-		} else {
-			np += "/"
-		}
-	}
-	return np
-}
-
-// Find a handler on a handler map given a path string.
-// Most-specific (longest) pattern wins.
-func (mux *ServeMux) match(path string) Responder {
-	// Check for exact match first.
-	v, ok := mux.m[path]
-	if ok {
-		return v.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) {
-			return e.r
-		}
-	}
-	return nil
-}
-
-// redirectToPathSlash determines if the given path needs appending "/" to it.
-// 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) {
-	mux.mu.RLock()
-	shouldRedirect := mux.shouldRedirectRLocked(path)
-	mux.mu.RUnlock()
-	if !shouldRedirect {
-		return u, false
-	}
-	path = path + "/"
-	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 {
-	if _, exist := mux.m[path]; exist {
-		return false
-	}
-
-	n := len(path)
-	if n == 0 {
-		return false
-	}
-	if _, exist := mux.m[path+"/"]; exist {
-		return path[n-1] != '/'
-	}
-
-	return false
-}
-
-// Respond dispatches the request to the responder whose
-// pattern most closely matches the request URL.
-func (mux *ServeMux) Respond(w *ResponseWriter, r *Request) {
-	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 {
-		Redirect(w, u.String())
-		return
-	}
-
-	if path != r.URL.Path {
-		u := *r.URL
-		u.Path = path
-		Redirect(w, u.String())
-		return
-	}
-
-	mux.mu.RLock()
-	defer mux.mu.RUnlock()
-
-	resp := mux.match(path)
-	if resp == nil {
-		w.WriteStatus(StatusNotFound)
-		return
-	}
-	resp.Respond(w, r)
-}
-
-// Handle registers the responder for the given pattern.
-// If a responder already exists for pattern, Handle panics.
-func (mux *ServeMux) Handle(pattern string, responder Responder) {
-	mux.mu.Lock()
-	defer mux.mu.Unlock()
-
-	if pattern == "" {
-		panic("gemini: invalid pattern")
-	}
-	if responder == nil {
-		panic("gemini: nil responder")
-	}
-	if _, exist := mux.m[pattern]; exist {
-		panic("gemini: multiple registrations for " + pattern)
-	}
-
-	if mux.m == nil {
-		mux.m = make(map[string]muxEntry)
-	}
-	e := muxEntry{responder, pattern}
-	mux.m[pattern] = e
-	if pattern[len(pattern)-1] == '/' {
-		mux.es = appendSorted(mux.es, e)
-	}
-}
-
-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)
-	})
-	if i == n {
-		return append(es, e)
-	}
-	// we now know that i points at where we want to insert
-	es = append(es, muxEntry{}) // try to grow the slice in place, any entry works.
-	copy(es[i+1:], es[i:])      // move shorter entries down
-	es[i] = e
-	return es
-}
-
-// HandleFunc registers the responder function for the given pattern.
-func (mux *ServeMux) HandleFunc(pattern string, responder func(*ResponseWriter, *Request)) {
-	if responder == nil {
-		panic("gemini: nil responder")
-	}
-	mux.Handle(pattern, ResponderFunc(responder))
-}

status.go

@@ -0,0 +1,85 @@
+package gemini
+
+// Status codes.
+type Status int
+
+const (
+	StatusInput                    Status = 10
+	StatusSensitiveInput           Status = 11
+	StatusSuccess                  Status = 20
+	StatusRedirect                 Status = 30
+	StatusPermanentRedirect        Status = 31
+	StatusTemporaryFailure         Status = 40
+	StatusServerUnavailable        Status = 41
+	StatusCGIError                 Status = 42
+	StatusProxyError               Status = 43
+	StatusSlowDown                 Status = 44
+	StatusPermanentFailure         Status = 50
+	StatusNotFound                 Status = 51
+	StatusGone                     Status = 52
+	StatusProxyRequestRefused      Status = 53
+	StatusBadRequest               Status = 59
+	StatusCertificateRequired      Status = 60
+	StatusCertificateNotAuthorized Status = 61
+	StatusCertificateNotValid      Status = 62
+)
+
+// Status code categories.
+type StatusClass int
+
+const (
+	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.
+func (s Status) Message() string {
+	switch s {
+	case StatusInput:
+		return "Input"
+	case StatusSensitiveInput:
+		return "Sensitive input"
+	case StatusSuccess:
+		return "Success"
+	case StatusRedirect:
+		return "Redirect"
+	case StatusPermanentRedirect:
+		return "Permanent redirect"
+	case StatusTemporaryFailure:
+		return "Temporary failure"
+	case StatusServerUnavailable:
+		return "Server unavailable"
+	case StatusCGIError:
+		return "CGI error"
+	case StatusProxyError:
+		return "Proxy error"
+	case StatusSlowDown:
+		return "Slow down"
+	case StatusPermanentFailure:
+		return "Permanent failure"
+	case StatusNotFound:
+		return "Not found"
+	case StatusGone:
+		return "Gone"
+	case StatusProxyRequestRefused:
+		return "Proxy request refused"
+	case StatusBadRequest:
+		return "Bad request"
+	case StatusCertificateRequired:
+		return "Certificate required"
+	case StatusCertificateNotAuthorized:
+		return "Certificate not authorized"
+	case StatusCertificateNotValid:
+		return "Certificate not valid"
+	}
+	return ""
+}

text.go

@@ -87,58 +87,68 @@ func (l LineText) line()                {}
 // Text represents a Gemini text response.
 type Text []Line
 
-// Parse parses Gemini text from the provided io.Reader.
-func Parse(r io.Reader) Text {
-	const spacetab = " \t"
+// ParseText parses Gemini text from the provided io.Reader.
+func ParseText(r io.Reader) Text {
 	var t Text
+	ParseLines(r, func(line Line) {
+		t = append(t, line)
+	})
+	return t
+}
+
+// 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)) {
+	const spacetab = " \t"
 	var pre bool
 	scanner := bufio.NewScanner(r)
 	for scanner.Scan() {
-		line := scanner.Text()
-		if strings.HasPrefix(line, "```") {
+		var line Line
+		text := scanner.Text()
+		if strings.HasPrefix(text, "```") {
 			pre = !pre
-			line = line[3:]
-			t = append(t, LinePreformattingToggle(line))
+			text = text[3:]
+			line = LinePreformattingToggle(text)
 		} else if pre {
-			t = append(t, LinePreformattedText(line))
-		} else if strings.HasPrefix(line, "=>") {
-			line = line[2:]
-			line = strings.TrimLeft(line, spacetab)
-			split := strings.IndexAny(line, spacetab)
+			line = LinePreformattedText(text)
+		} else if strings.HasPrefix(text, "=>") {
+			text = text[2:]
+			text = strings.TrimLeft(text, spacetab)
+			split := strings.IndexAny(text, spacetab)
 			if split == -1 {
-				// line is a URL
-				t = append(t, LineLink{URL: line})
+				// text is a URL
+				line = LineLink{URL: text}
 			} else {
-				url := line[:split]
-				name := line[split:]
+				url := text[:split]
+				name := text[split:]
 				name = strings.TrimLeft(name, spacetab)
-				t = append(t, LineLink{url, name})
+				line = LineLink{url, name}
 			}
-		} else if strings.HasPrefix(line, "*") {
-			line = line[1:]
-			line = strings.TrimLeft(line, spacetab)
-			t = append(t, LineListItem(line))
-		} else if strings.HasPrefix(line, "###") {
-			line = line[3:]
-			line = strings.TrimLeft(line, spacetab)
-			t = append(t, LineHeading3(line))
-		} else if strings.HasPrefix(line, "##") {
-			line = line[2:]
-			line = strings.TrimLeft(line, spacetab)
-			t = append(t, LineHeading2(line))
-		} else if strings.HasPrefix(line, "#") {
-			line = line[1:]
-			line = strings.TrimLeft(line, spacetab)
-			t = append(t, LineHeading1(line))
-		} else if strings.HasPrefix(line, ">") {
-			line = line[1:]
-			line = strings.TrimLeft(line, spacetab)
-			t = append(t, LineQuote(line))
+		} else if strings.HasPrefix(text, "*") {
+			text = text[1:]
+			text = strings.TrimLeft(text, spacetab)
+			line = LineListItem(text)
+		} else if strings.HasPrefix(text, "###") {
+			text = text[3:]
+			text = strings.TrimLeft(text, spacetab)
+			line = LineHeading3(text)
+		} else if strings.HasPrefix(text, "##") {
+			text = text[2:]
+			text = strings.TrimLeft(text, spacetab)
+			line = LineHeading2(text)
+		} else if strings.HasPrefix(text, "#") {
+			text = text[1:]
+			text = strings.TrimLeft(text, spacetab)
+			line = LineHeading1(text)
+		} else if strings.HasPrefix(text, ">") {
+			text = text[1:]
+			text = strings.TrimLeft(text, spacetab)
+			line = LineQuote(text)
 		} else {
-			t = append(t, LineText(line))
+			line = LineText(text)
 		}
+		handler(line)
 	}
-	return t
 }
 
 // String writes the Gemini text response to a string and returns it.

tofu.go

@@ -2,118 +2,101 @@ package gemini
 
 import (
 	"bufio"
-	"bytes"
 	"crypto/sha512"
-	"crypto/x509"
 	"fmt"
 	"io"
 	"os"
-	"path/filepath"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
-// KnownHosts represents a list of known hosts.
-// The zero value for KnownHosts is an empty list ready to use.
-type KnownHosts struct {
-	hosts map[string]certInfo
-	file  *os.File
+// 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.
+//
+// KnownHostsFile is safe for concurrent use by multiple goroutines.
+type KnownHostsFile struct {
+	KnownHosts
+	out io.Writer
+	mu  sync.RWMutex
 }
 
-// LoadDefault loads the known hosts from the default known hosts path, which is
-// $XDG_DATA_HOME/gemini/known_hosts.
-// It creates the path and any of its parent directories if they do not exist.
-// KnownHosts will append to the file whenever a certificate is added.
-func (k *KnownHosts) LoadDefault() error {
-	path, err := defaultKnownHostsPath()
-	if err != nil {
-		return err
+// SetOutput sets the output to which new known hosts will be written to.
+func (k *KnownHostsFile) SetOutput(w io.Writer) {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	k.out = w
+}
+
+// Add adds a known host to the list of known hosts.
+func (k *KnownHostsFile) Add(hostname string, fingerprint Fingerprint) {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	if k.KnownHosts == nil {
+		k.KnownHosts = KnownHosts{}
 	}
-	return k.Load(path)
+	k.KnownHosts[hostname] = fingerprint
 }
 
-// Load loads the known hosts from the provided path.
-// It creates the path and any of its parent directories if they do not exist.
-// KnownHosts will append to the file whenever a certificate is added.
-func (k *KnownHosts) Load(path string) error {
-	if dir := filepath.Dir(path); dir != "." {
-		err := os.MkdirAll(dir, 0755)
-		if err != nil {
+// Lookup returns the fingerprint of the certificate corresponding to
+// the given hostname.
+func (k *KnownHostsFile) Lookup(hostname string) (Fingerprint, bool) {
+	k.mu.RLock()
+	defer k.mu.RUnlock()
+	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) {
+	k.mu.RLock()
+	defer k.mu.RUnlock()
+	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 {
+	k.mu.RLock()
+	defer k.mu.RUnlock()
+	for h, c := range k.KnownHosts {
+		if _, err := k.writeKnownHost(w, h, c); err != nil {
 			return err
 		}
 	}
-	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDONLY, 0644)
+	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_RDWR, 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.file = f
+	k.SetOutput(f)
 	return nil
 }
 
-// Add adds a certificate to the list of known hosts.
-// If KnownHosts was loaded from a file, Add will append to the file.
-func (k *KnownHosts) Add(hostname string, cert *x509.Certificate) {
-	k.add(hostname, cert, true)
-}
-
-// AddTemporary adds a certificate to the list of known hosts
-// without writing it to the known hosts file.
-func (k *KnownHosts) AddTemporary(hostname string, cert *x509.Certificate) {
-	k.add(hostname, cert, false)
-}
-
-func (k *KnownHosts) add(hostname string, cert *x509.Certificate, write bool) {
-	if k.hosts == nil {
-		k.hosts = map[string]certInfo{}
-	}
-	info := certInfo{
-		Algorithm:   "SHA-512",
-		Fingerprint: Fingerprint(cert),
-		Expires:     cert.NotAfter.Unix(),
-	}
-	k.hosts[hostname] = info
-	// Append to the file
-	if write && k.file != nil {
-		appendKnownHost(k.file, hostname, info)
-	}
-}
-
-// Lookup looks for the provided certificate in the list of known hosts.
-// If the hostname is in the list, but the fingerprint differs,
-// Lookup returns ErrCertificateNotTrusted.
-// If the hostname is not in the list, Lookup returns ErrCertificateUnknown.
-// If the certificate is found and the fingerprint matches, error will be nil.
-func (k *KnownHosts) Lookup(hostname string, cert *x509.Certificate) error {
-	now := time.Now().Unix()
-	fingerprint := Fingerprint(cert)
-	if c, ok := k.hosts[hostname]; ok {
-		if c.Expires <= now {
-			// Certificate is expired
-			return ErrCertificateUnknown
-		}
-		if c.Fingerprint != fingerprint {
-			// Fingerprint does not match
-			return ErrCertificateNotTrusted
-		}
-		// Certificate is trusted
-		return nil
-	}
-	return ErrCertificateUnknown
-}
-
 // Parse parses the provided reader and adds the parsed known hosts to the list.
-// Invalid lines are ignored.
-func (k *KnownHosts) Parse(r io.Reader) {
-	if k.hosts == nil {
-		k.hosts = map[string]certInfo{}
+// Invalid entries are ignored.
+func (k *KnownHostsFile) Parse(r io.Reader) {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	if k.KnownHosts == nil {
+		k.KnownHosts = map[string]Fingerprint{}
 	}
 	scanner := bufio.NewScanner(r)
 	for scanner.Scan() {
@@ -128,70 +111,42 @@ func (k *KnownHosts) Parse(r io.Reader) {
 		if algorithm != "SHA-512" {
 			continue
 		}
-		fingerprint := parts[2]
-		expires, err := strconv.ParseInt(parts[3], 10, 0)
+		hex := parts[2]
+
+		unix, err := strconv.ParseInt(parts[3], 10, 0)
 		if err != nil {
 			continue
 		}
+		expires := time.Unix(unix, 0)
 
-		k.hosts[hostname] = certInfo{
-			Algorithm:   algorithm,
-			Fingerprint: fingerprint,
-			Expires:     expires,
+		k.KnownHosts[hostname] = Fingerprint{
+			Algorithm: algorithm,
+			Hex:       hex,
+			Expires:   expires,
 		}
 	}
 }
 
-// Write writes the known hosts to the provided io.Writer.
-func (k *KnownHosts) Write(w io.Writer) {
-	for h, c := range k.hosts {
-		appendKnownHost(w, h, c)
-	}
+// 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
 }
 
-type certInfo struct {
-	Algorithm   string // fingerprint algorithm e.g. SHA-512
-	Fingerprint string // fingerprint in hexadecimal, with ':' between each octet
-	Expires     int64  // unix time of certificate notAfter date
-}
-
-func appendKnownHost(w io.Writer, hostname string, c certInfo) (int, error) {
-	return fmt.Fprintf(w, "%s %s %s %d\n", hostname, c.Algorithm, c.Fingerprint, c.Expires)
-}
-
-// Fingerprint returns the SHA-512 fingerprint of the provided certificate.
-func Fingerprint(cert *x509.Certificate) string {
-	sum512 := sha512.Sum512(cert.Raw)
-	var buf bytes.Buffer
+// 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 {
-			fmt.Fprintf(&buf, ":")
+			b.WriteByte(':')
 		}
-		fmt.Fprintf(&buf, "%02X", f)
+		fmt.Fprintf(&b, "%02X", f)
+	}
+	return Fingerprint{
+		Algorithm: "SHA-512",
+		Hex:       b.String(),
+		Expires:   expires,
 	}
-	return buf.String()
-}
-
-// defaultKnownHostsPath returns the default known_hosts path.
-// The default path is $XDG_DATA_HOME/gemini/known_hosts
-func defaultKnownHostsPath() (string, error) {
-	dataDir, err := userDataDir()
-	if err != nil {
-		return "", err
-	}
-	return filepath.Join(dataDir, "gemini", "known_hosts"), nil
-}
-
-// userDataDir returns the user data directory.
-func userDataDir() (string, error) {
-	dataDir, ok := os.LookupEnv("XDG_DATA_HOME")
-	if ok {
-		return dataDir, nil
-	}
-
-	home, err := os.UserHomeDir()
-	if err != nil {
-		return "", err
-	}
-	return filepath.Join(home, ".local", "share"), nil
 }