From 610c6fc53344cad3c4b730466e7da7d6eb43a7eb Mon Sep 17 00:00:00 2001
From: Adnan Maolood <me@adnano.co>
Date: Tue, 3 Nov 2020 16:11:31 -0500
Subject: [PATCH] Add ErrorLog field to Server

---
 cert.go          |  7 +++----
 examples/auth.go |  1 +
 server.go        | 19 +++++++++++++++++--
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/cert.go b/cert.go
index 8079a8a..702584c 100644
--- a/cert.go
+++ b/cert.go
@@ -8,7 +8,6 @@ import (
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
-	"log"
 	"math/big"
 	"net"
 	"os"
@@ -27,7 +26,7 @@ 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{}
 	}
@@ -40,14 +39,14 @@ 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.
diff --git a/examples/auth.go b/examples/auth.go
index 41fb70c..13597bb 100644
--- a/examples/auth.go
+++ b/examples/auth.go
@@ -119,6 +119,7 @@ func logout(w *gemini.ResponseWriter, r *gemini.Request) {
 	fingerprint := gemini.Fingerprint(r.Certificate.Leaf)
 	delete(sessions, fingerprint)
 	fmt.Fprintln(w, "Successfully logged out.")
+	fmt.Fprintln(w, "=> / Index")
 }
 
 func profile(w *gemini.ResponseWriter, r *gemini.Request) {
diff --git a/server.go b/server.go
index 45555fc..8db210e 100644
--- a/server.go
+++ b/server.go
@@ -31,6 +31,11 @@ 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 +122,7 @@ 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
 			}
@@ -154,7 +159,9 @@ func (s *Server) getCertificateFor(hostname string) (*tls.Certificate, error) {
 		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
 		}
@@ -241,6 +248,14 @@ 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