Don't redirect by default

cert.go

@@ -2,12 +2,14 @@ package gemini
 
 import (
 	"crypto"
+	"crypto/ecdsa"
 	"crypto/ed25519"
+	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
 	"encoding/pem"
-	"log"
 	"math/big"
 	"net"
 	"os"
@@ -26,7 +28,7 @@ type CertificateStore struct {
 
 // 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(scope string, cert tls.Certificate) {
+func (c *CertificateStore) Add(scope string, cert tls.Certificate) error {
 	if c.store == nil {
 		c.store = map[string]tls.Certificate{}
 	}
@@ -39,27 +41,20 @@ func (c *CertificateStore) Add(scope string, cert tls.Certificate) {
 	}
 	if c.dir {
 		// Write certificates
-		log.Printf("gemini: Writing certificate for %s to %s", scope, c.path)
 		certPath := filepath.Join(c.path, scope+".crt")
 		keyPath := filepath.Join(c.path, scope+".key")
 		if err := WriteCertificate(cert, certPath, keyPath); err != nil {
-			log.Printf("gemini: Failed to write certificate for %s: %s", scope, err)
+			return err
 		}
 	}
 	c.store[scope] = cert
+	return nil
 }
 
 // Lookup returns the certificate for the given scope.
-func (c *CertificateStore) Lookup(scope string) (*tls.Certificate, error) {
+func (c *CertificateStore) Lookup(scope string) (tls.Certificate, bool) {
 	cert, ok := c.store[scope]
-	if !ok {
+	return cert, ok
-		return nil, ErrCertificateNotFound
-	}
-	// Ensure that the certificate is not expired
-	if cert.Leaf != nil && cert.Leaf.NotAfter.Before(time.Now()) {
-		return &cert, ErrCertificateExpired
-	}
-	return &cert, nil
 }
 
 // Load loads certificates from the given path.
@@ -87,11 +82,31 @@ func (c *CertificateStore) Load(path string) error {
 	return nil
 }
 
-// CertificateOptions configures how a certificate is created.
+// 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
-	DNSNames    []string
+
-	Duration    time.Duration
+	// 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.
@@ -109,15 +124,27 @@ func CreateCertificate(options CertificateOptions) (tls.Certificate, error) {
 
 // newX509KeyPair creates and returns a new certificate and private key.
 func newX509KeyPair(options CertificateOptions) (*x509.Certificate, crypto.PrivateKey, error) {
-	// Generate an ED25519 private key
+	var pub crypto.PublicKey
-	_, priv, err := ed25519.GenerateKey(rand.Reader)
+	var priv crypto.PrivateKey
-	if err != nil {
+	if options.Ed25519 {
-		return nil, nil, err
+		// 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
+	// ECDSA and Ed25519 keys should have the DigitalSignature KeyUsage bits
-	// in the x509.Certificate template
+	// set in the x509.Certificate template
 	keyUsage := x509.KeyUsageDigitalSignature
 
 	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
@@ -138,9 +165,10 @@ func newX509KeyPair(options CertificateOptions) (*x509.Certificate, crypto.Priva
 		BasicConstraintsValid: true,
 		IPAddresses:           options.IPAddresses,
 		DNSNames:              options.DNSNames,
+		Subject:               options.Subject,
 	}
 
-	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
 	}

client.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"crypto/tls"
 	"crypto/x509"
+	"errors"
 	"net"
 	"net/url"
 	"path"
@@ -39,8 +40,7 @@ type Client struct {
 	GetInput func(prompt string, sensitive bool) (input string, ok bool)
 
 	// CheckRedirect determines whether to follow a redirect.
-	// If CheckRedirect is nil, a default policy of no more than 5 consecutive
+	// If CheckRedirect is nil, redirects will not be followed.
-	// redirects will be enforced.
 	CheckRedirect func(req *Request, via []*Request) error
 
 	// CreateCertificate is called to generate a certificate upon
@@ -125,9 +125,10 @@ func (c *Client) do(req *Request, via []*Request) (*Response, error) {
 				return resp, err
 			}
 			c.Certificates.Add(hostname+path, cert)
+			req.Certificate = &cert
 			return c.do(req, via)
 		}
-		return resp, ErrCertificateRequired
+		return resp, nil
 
 	case resp.Status.Class() == StatusClassInput:
 		if c.GetInput != nil {
@@ -138,7 +139,7 @@ func (c *Client) do(req *Request, via []*Request) (*Response, error) {
 				return c.do(req, via)
 			}
 		}
-		return resp, ErrInputRequired
+		return resp, nil
 
 	case resp.Status.Class() == StatusClassRedirect:
 		if via == nil {
@@ -150,21 +151,19 @@ func (c *Client) do(req *Request, via []*Request) (*Response, error) {
 		if err != nil {
 			return resp, err
 		}
+
 		target = req.URL.ResolveReference(target)
-		redirect, err := NewRequestFromURL(target)
+		if target.Scheme != "" && target.Scheme != "gemini" {
-		if err != nil {
+			return resp, nil
-			return resp, err
 		}
 
+		redirect := NewRequestFromURL(target)
 		if c.CheckRedirect != nil {
 			if err := c.CheckRedirect(redirect, via); err != nil {
 				return resp, err
 			}
-		} else if len(via) > 5 {
+			return c.do(redirect, via)
-			// Default policy of no more than 5 redirects
-			return resp, ErrTooManyRedirects
 		}
-		return c.do(redirect, via)
 	}
 
 	resp.Request = req
@@ -180,13 +179,14 @@ func (c *Client) getClientCertificate(req *Request) (*tls.Certificate, error) {
 	// Search recursively for the certificate
 	scope := req.URL.Hostname() + strings.TrimSuffix(req.URL.Path, "/")
 	for {
-		cert, err := c.Certificates.Lookup(scope)
+		cert, ok := c.Certificates.Lookup(scope)
-		if err == nil {
+		if ok {
-			// Store the certificate
+			// Ensure that the certificate is not expired
-			req.Certificate = cert
+			if cert.Leaf != nil && !time.Now().After(cert.Leaf.NotAfter) {
-			return cert, err
+				// Store the certificate
-		}
+				req.Certificate = &cert
-		if err == ErrCertificateExpired {
+				return &cert, nil
+			}
 			break
 		}
 		scope = path.Dir(scope)
@@ -214,21 +214,27 @@ func (c *Client) verifyConnection(req *Request, cs tls.ConnectionState) error {
 		return nil
 	}
 	// Check the known hosts
-	err := c.KnownHosts.Lookup(hostname, cert)
+	knownHost, ok := c.KnownHosts.Lookup(hostname)
-	switch err {
+	if ok && time.Now().After(cert.NotAfter) {
-	case ErrCertificateExpired, ErrCertificateNotFound:
+		// Not expired
-		// See if the client trusts the certificate
+		fingerprint := NewFingerprint(cert)
-		if c.TrustCertificate != nil {
+		if knownHost.Hex != fingerprint.Hex {
-			switch c.TrustCertificate(hostname, cert) {
+			return errors.New("gemini: fingerprint does not match")
-			case TrustOnce:
-				c.KnownHosts.AddTemporary(hostname, cert)
-				return nil
-			case TrustAlways:
-				c.KnownHosts.Add(hostname, cert)
-				return nil
-			}
 		}
-		return ErrCertificateNotTrusted
+		return nil
 	}
-	return err
+
+	// Unknown certificate
+	// See if the client trusts the certificate
+	if c.TrustCertificate != nil {
+		switch c.TrustCertificate(hostname, cert) {
+		case TrustOnce:
+			c.KnownHosts.AddTemporary(hostname, cert)
+			return nil
+		case TrustAlways:
+			c.KnownHosts.Add(hostname, cert)
+			return nil
+		}
+	}
+	return errors.New("gemini: certificate not trusted")
 }

examples/auth.go

@@ -5,6 +5,7 @@ package main
 import (
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
 	"fmt"
 	"log"
 	"time"
@@ -48,6 +49,9 @@ func main() {
 	}
 	server.CreateCertificate = func(hostname string) (tls.Certificate, error) {
 		return gemini.CreateCertificate(gemini.CertificateOptions{
+			Subject: pkix.Name{
+				CommonName: hostname,
+			},
 			DNSNames: []string{hostname},
 			Duration: time.Hour,
 		})
@@ -60,8 +64,8 @@ func main() {
 }
 
 func getSession(cert *x509.Certificate) (*session, bool) {
-	fingerprint := gemini.Fingerprint(cert)
+	fingerprint := gemini.NewFingerprint(cert)
-	session, ok := sessions[fingerprint]
+	session, ok := sessions[fingerprint.Hex]
 	return session, ok
 }
 
@@ -75,8 +79,8 @@ func login(w *gemini.ResponseWriter, r *gemini.Request) {
 		w.WriteHeader(gemini.StatusInput, "Username")
 		return
 	}
-	fingerprint := gemini.Fingerprint(r.Certificate.Leaf)
+	fingerprint := gemini.NewFingerprint(r.Certificate.Leaf)
-	sessions[fingerprint] = &session{
+	sessions[fingerprint.Hex] = &session{
 		username: username,
 	}
 	w.WriteHeader(gemini.StatusRedirect, "/password")
@@ -103,7 +107,7 @@ func loginPassword(w *gemini.ResponseWriter, r *gemini.Request) {
 		session.authorized = true
 		w.WriteHeader(gemini.StatusRedirect, "/profile")
 	} else {
-		w.WriteHeader(gemini.StatusSensitiveInput, "Wrong password. Try again")
+		w.WriteHeader(gemini.StatusSensitiveInput, "Password")
 	}
 }
 
@@ -112,9 +116,10 @@ func logout(w *gemini.ResponseWriter, r *gemini.Request) {
 		w.WriteStatus(gemini.StatusCertificateRequired)
 		return
 	}
-	fingerprint := gemini.Fingerprint(r.Certificate.Leaf)
+	fingerprint := gemini.NewFingerprint(r.Certificate.Leaf)
-	delete(sessions, fingerprint)
+	delete(sessions, fingerprint.Hex)
 	fmt.Fprintln(w, "Successfully logged out.")
+	fmt.Fprintln(w, "=> / Index")
 }
 
 func profile(w *gemini.ResponseWriter, r *gemini.Request) {

examples/cert.go

@@ -3,6 +3,7 @@
 package main
 
 import (
+	"crypto/x509/pkix"
 	"fmt"
 	"log"
 	"os"
@@ -22,6 +23,9 @@ func main() {
 		log.Fatal(err)
 	}
 	options := gemini.CertificateOptions{
+		Subject: pkix.Name{
+			CommonName: host,
+		},
 		DNSNames: []string{host},
 		Duration: duration,
 	}

examples/client.go

@@ -33,7 +33,8 @@ func init() {
 	client.Timeout = 30 * time.Second
 	client.KnownHosts.LoadDefault()
 	client.TrustCertificate = func(hostname string, cert *x509.Certificate) gemini.Trust {
-		fmt.Printf(trustPrompt, hostname, gemini.Fingerprint(cert))
+		fingerprint := gemini.NewFingerprint(cert)
+		fmt.Printf(trustPrompt, hostname, fingerprint.Hex)
 		scanner.Scan()
 		switch scanner.Text() {
 		case "t":

examples/server.go

@@ -4,6 +4,7 @@ package main
 
 import (
 	"crypto/tls"
+	"crypto/x509/pkix"
 	"log"
 	"time"
 
@@ -19,6 +20,9 @@ func main() {
 	}
 	server.CreateCertificate = func(hostname string) (tls.Certificate, error) {
 		return gemini.CreateCertificate(gemini.CertificateOptions{
+			Subject: pkix.Name{
+				CommonName: hostname,
+			},
 			DNSNames: []string{hostname},
 			Duration: time.Minute, // for testing purposes
 		})

fs.go

@@ -96,9 +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

@@ -9,17 +9,9 @@ var crlf = []byte("\r\n")
 
 // Errors.
 var (
-	ErrInvalidURL            = errors.New("gemini: invalid URL")
+	ErrInvalidURL      = errors.New("gemini: invalid URL")
-	ErrInvalidResponse       = errors.New("gemini: invalid response")
+	ErrInvalidResponse = errors.New("gemini: invalid response")
-	ErrCertificateExpired    = errors.New("gemini: certificate expired")
+	ErrBodyNotAllowed  = errors.New("gemini: response body not allowed")
-	ErrCertificateNotFound   = errors.New("gemini: certificate not found")
-	ErrCertificateNotTrusted = errors.New("gemini: certificate not trusted")
-	ErrCertificateRequired   = errors.New("gemini: certificate required")
-	ErrNotAFile              = errors.New("gemini: not a file")
-	ErrNotAGeminiURL         = errors.New("gemini: not a Gemini URL")
-	ErrBodyNotAllowed        = errors.New("gemini: response status code does not allow for body")
-	ErrTooManyRedirects      = errors.New("gemini: too many redirects")
-	ErrInputRequired         = errors.New("gemini: input required")
 )
 
 // defaultClient is the default client. It is used by Get and Do.

request.go

@@ -41,15 +41,12 @@ 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) {
+func NewRequestFromURL(url *url.URL) *Request {
-	if url.Scheme != "" && url.Scheme != "gemini" {
-		return nil, ErrNotAGeminiURL
-	}
 	host := url.Host
 	if url.Port() == "" {
 		host += ":1965"
@@ -57,7 +54,7 @@ func NewRequestFromURL(url *url.URL) (*Request, error) {
 	return &Request{
 		URL:  url,
 		Host: host,
-	}, nil
+	}
 }
 
 // write writes the Gemini request to the provided buffered writer.

server.go

@@ -3,6 +3,7 @@ package gemini
 import (
 	"bufio"
 	"crypto/tls"
+	"errors"
 	"log"
 	"net"
 	"net/url"
@@ -31,6 +32,11 @@ type Server struct {
 	// 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
@@ -117,7 +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
 			}
@@ -145,22 +151,24 @@ func (s *Server) getCertificate(h *tls.ClientHelloInfo) (*tls.Certificate, error
 
 func (s *Server) getCertificateFor(hostname string) (*tls.Certificate, error) {
 	if _, ok := s.hosts[hostname]; !ok {
-		return nil, ErrCertificateNotFound
+		return nil, errors.New("hostname not registered")
 	}
-	cert, err := s.Certificates.Lookup(hostname)
 
-	switch err {
+	// Generate a new certificate if it is missing or expired
-	case ErrCertificateNotFound, ErrCertificateExpired:
+	cert, ok := s.Certificates.Lookup(hostname)
+	if !ok || cert.Leaf != nil && !time.Now().After(cert.Leaf.NotAfter) {
 		if s.CreateCertificate != nil {
 			cert, err := s.CreateCertificate(hostname)
 			if err == nil {
-				s.Certificates.Add(hostname, cert)
+				if err := s.Certificates.Add(hostname, cert); err != nil {
+					s.logf("gemini: Failed to add new certificate for %s: %s", hostname, err)
+				}
 			}
 			return &cert, err
 		}
+		return nil, errors.New("no certificate")
 	}
-
+	return &cert, nil
-	return cert, err
 }
 
 // respond responds to a connection.
@@ -241,6 +249,14 @@ func (s *Server) responder(r *Request) Responder {
 	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

tofu.go

@@ -8,9 +8,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"strconv"
 	"strings"
-	"time"
 )
 
 // Trust represents the trustworthiness of a certificate.
@@ -25,7 +23,7 @@ const (
 // 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
+	hosts map[string]Fingerprint
 	file  *os.File
 }
 
@@ -80,53 +78,34 @@ func (k *KnownHosts) AddTemporary(hostname string, cert *x509.Certificate) {
 
 func (k *KnownHosts) add(hostname string, cert *x509.Certificate, write bool) {
 	if k.hosts == nil {
-		k.hosts = map[string]certInfo{}
+		k.hosts = map[string]Fingerprint{}
 	}
-	info := certInfo{
+	fingerprint := NewFingerprint(cert)
-		Algorithm:   "SHA-512",
+	k.hosts[hostname] = fingerprint
-		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)
+		appendKnownHost(k.file, hostname, fingerprint)
 	}
 }
 
-// Lookup looks for the provided certificate in the list of known hosts.
+// Lookup returns the fingerprint of the certificate corresponding to
-// If the hostname is not in the list, Lookup returns ErrCertificateNotFound.
+// the given hostname.
-// If the fingerprint doesn't match, Lookup returns ErrCertificateNotTrusted.
+func (k *KnownHosts) Lookup(hostname string) (Fingerprint, bool) {
-// Otherwise, Lookup returns nil.
+	c, ok := k.hosts[hostname]
-func (k *KnownHosts) Lookup(hostname string, cert *x509.Certificate) error {
+	return c, ok
-	now := time.Now().Unix()
-	fingerprint := Fingerprint(cert)
-	if c, ok := k.hosts[hostname]; ok {
-		if c.Expires <= now {
-			// Certificate is expired
-			return ErrCertificateExpired
-		}
-		if c.Fingerprint != fingerprint {
-			// Fingerprint does not match
-			return ErrCertificateNotTrusted
-		}
-		// Certificate is found
-		return nil
-	}
-	return ErrCertificateNotFound
 }
 
 // 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{}
+		k.hosts = map[string]Fingerprint{}
 	}
 	scanner := bufio.NewScanner(r)
 	for scanner.Scan() {
 		text := scanner.Text()
 		parts := strings.Split(text, " ")
-		if len(parts) < 4 {
+		if len(parts) < 3 {
 			continue
 		}
 
@@ -136,15 +115,10 @@ func (k *KnownHosts) Parse(r io.Reader) {
 			continue
 		}
 		fingerprint := parts[2]
-		expires, err := strconv.ParseInt(parts[3], 10, 0)
-		if err != nil {
-			continue
-		}
 
-		k.hosts[hostname] = certInfo{
+		k.hosts[hostname] = Fingerprint{
-			Algorithm:   algorithm,
+			Algorithm: algorithm,
-			Fingerprint: fingerprint,
+			Hex:       fingerprint,
-			Expires:     expires,
 		}
 	}
 }
@@ -156,18 +130,18 @@ func (k *KnownHosts) Write(w io.Writer) {
 	}
 }
 
-type certInfo struct {
+func appendKnownHost(w io.Writer, hostname string, f Fingerprint) (int, error) {
-	Algorithm   string // fingerprint algorithm e.g. SHA-512
+	return fmt.Fprintf(w, "%s %s %s\n", hostname, f.Algorithm, f.Hex)
-	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) {
+// Fingerprint represents a fingerprint using a certain algorithm.
-	return fmt.Fprintf(w, "%s %s %s %d\n", hostname, c.Algorithm, c.Fingerprint, c.Expires)
+type Fingerprint struct {
+	Algorithm string // fingerprint algorithm e.g. SHA-512
+	Hex       string // fingerprint in hexadecimal, with ':' between each octet
 }
 
-// Fingerprint returns the SHA-512 fingerprint of the provided certificate.
+// NewFingerprint returns the SHA-512 fingerprint of the provided certificate.
-func Fingerprint(cert *x509.Certificate) string {
+func NewFingerprint(cert *x509.Certificate) Fingerprint {
 	sum512 := sha512.Sum512(cert.Raw)
 	var b strings.Builder
 	for i, f := range sum512 {
@@ -176,7 +150,10 @@ func Fingerprint(cert *x509.Certificate) string {
 		}
 		fmt.Fprintf(&b, "%02X", f)
 	}
-	return b.String()
+	return Fingerprint{
+		Algorithm: "SHA-512",
+		Hex:       b.String(),
+	}
 }
 
 // defaultKnownHostsPath returns the default known_hosts path.