From 6884281d8654e67beb2474fbe5b3f0189c9bb703 Mon Sep 17 00:00:00 2001
From: adnano <me@adnano.co>
Date: Mon, 21 Sep 2020 18:21:42 -0400
Subject: [PATCH] Add support for client-side certificates

---
 client.go                 | 25 ++++++++++++++++++-------
 example/client/.gitignore |  2 ++
 example/client/client.go  | 21 ++++++++++++++++++++-
 example/server/server.go  |  2 +-
 server.go                 |  4 ++--
 5 files changed, 43 insertions(+), 11 deletions(-)
 create mode 100644 example/client/.gitignore

diff --git a/client.go b/client.go
index a25b6d0..fda626e 100644
--- a/client.go
+++ b/client.go
@@ -16,7 +16,19 @@ var (
 
 // Client is a Gemini client.
 type Client struct {
-	TLSConfig *tls.Config // TODO: Client certificate support
+	// The client's TLS configuration.
+	// To use a client-side certificate, provide it here.
+	//
+	// Example:
+	//
+	//     config := tls.Config{}
+	//     cert, err := tls.LoadX509KeyPair("example/server/server.crt", "example/server/server.key")
+	//     if err != nil {
+	//         panic(err)
+	//     }
+	//     config.Certificates = append(config.Certificates, cert)
+	//
+	TLSConfig tls.Config
 }
 
 // Request makes a request for the provided URL. The host is inferred from the URL.
@@ -83,12 +95,11 @@ func (c *Client) Do(req *Request) (*Response, error) {
 		host += ":1965"
 	}
 
-	config := &tls.Config{
-		// Allow self-signed certificates
-		// TODO: Trust on first use
-		InsecureSkipVerify: true,
-	}
-	conn, err := tls.Dial("tcp", host, config)
+	// Allow self signed certificates
+	config := c.TLSConfig
+	config.InsecureSkipVerify = true
+
+	conn, err := tls.Dial("tcp", host, &config)
 	if err != nil {
 		return nil, err
 	}
diff --git a/example/client/.gitignore b/example/client/.gitignore
new file mode 100644
index 0000000..37278c1
--- /dev/null
+++ b/example/client/.gitignore
@@ -0,0 +1,2 @@
+client.crt
+client.key
diff --git a/example/client/client.go b/example/client/client.go
index 5b6fde2..0dac61b 100644
--- a/example/client/client.go
+++ b/example/client/client.go
@@ -4,14 +4,33 @@ package main
 
 import (
 	"bufio"
+	"crypto/tls"
 	"fmt"
-	"git.sr.ht/~adnano/go-gemini"
 	"log"
 	"os"
+
+	"git.sr.ht/~adnano/go-gemini"
 )
 
 var client gemini.Client
 
+func init() {
+	// Configure a client side certificate.
+	// To generate a certificate, run:
+	//
+	//     openssl genrsa -out client.key 2048
+	//     openssl ecparam -genkey -name secp384r1 -out client.key
+	//     openssl req -new -x509 -sha256 -key client.key -out client.crt -days 3650
+	//
+	config := tls.Config{}
+	cert, err := tls.LoadX509KeyPair("example/client/client.crt", "example/client/client.key")
+	if err != nil {
+		log.Fatal(err)
+	}
+	config.Certificates = append(config.Certificates, cert)
+	client.TLSConfig = config
+}
+
 func makeRequest(url string) {
 	resp, err := client.Request(url)
 	if err != nil {
diff --git a/example/server/server.go b/example/server/server.go
index 3f0a3e3..dbb23a0 100644
--- a/example/server/server.go
+++ b/example/server/server.go
@@ -17,7 +17,7 @@ func main() {
 	//     openssl ecparam -genkey -name secp384r1 -out server.key
 	//     openssl req -new -x509 -sha256 -key server.key -out server.crt -days 3650
 	//
-	config := &tls.Config{}
+	config := tls.Config{}
 	cert, err := tls.LoadX509KeyPair("example/server/server.crt", "example/server/server.key")
 	if err != nil {
 		log.Fatal(err)
diff --git a/server.go b/server.go
index e039f67..a42588b 100644
--- a/server.go
+++ b/server.go
@@ -62,7 +62,7 @@ func (r *Response) Write(w io.Writer) {
 // Server is a Gemini server.
 type Server struct {
 	Addr      string
-	TLSConfig *tls.Config
+	TLSConfig tls.Config
 	Handler   Handler
 }
 
@@ -79,7 +79,7 @@ func (s *Server) ListenAndServe() error {
 	}
 	defer ln.Close()
 
-	tlsListener := tls.NewListener(ln, s.TLSConfig)
+	tlsListener := tls.NewListener(ln, &s.TLSConfig)
 	return s.Serve(tlsListener)
 }