From 7be849d4a6bb8771ac2914e9166a8e10c7d7300c Mon Sep 17 00:00:00 2001
From: Adam Langley <agl@golang.org>
Date: Wed, 21 Jul 2010 11:36:01 -0400
Subject: [PATCH] crypto/tls: add client-side SNI support and PeerCertificates.

SNI (Server Name Indication) is a way for a TLS client to
indicate to the server which name it knows the server by. This
allows the server to have several names and return the correct
certificate for each (virtual hosting).

PeerCertificates returns the list of certificates presented by
server.

R=r
CC=golang-dev
https://golang.org/cl/1741053
---
 src/pkg/crypto/tls/common.go             |  3 +++
 src/pkg/crypto/tls/conn.go               | 11 +++++++++++
 src/pkg/crypto/tls/handshake_client.go   |  3 +++
 src/pkg/crypto/tls/handshake_messages.go |  3 ++-
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/pkg/crypto/tls/common.go b/src/pkg/crypto/tls/common.go
index 7c6940aa32..717ae0a815 100644
--- a/src/pkg/crypto/tls/common.go
+++ b/src/pkg/crypto/tls/common.go
@@ -85,6 +85,9 @@ type Config struct {
 	// NextProtos is a list of supported, application level protocols.
 	// Currently only server-side handling is supported.
 	NextProtos []string
+	// ServerName is included in the client's handshake to support virtual
+	// hosting.
+	ServerName string
 }
 
 type Certificate struct {
diff --git a/src/pkg/crypto/tls/conn.go b/src/pkg/crypto/tls/conn.go
index aa224e49d2..7f5d97d4be 100644
--- a/src/pkg/crypto/tls/conn.go
+++ b/src/pkg/crypto/tls/conn.go
@@ -5,6 +5,7 @@ package tls
 import (
 	"bytes"
 	"crypto/subtle"
+	"crypto/x509"
 	"hash"
 	"io"
 	"net"
@@ -27,6 +28,7 @@ type Conn struct {
 	handshakeComplete bool
 	cipherSuite       uint16
 	ocspResponse      []byte // stapled OCSP response
+	peerCertificates  []*x509.Certificate
 
 	clientProtocol string
 
@@ -651,3 +653,12 @@ func (c *Conn) OCSPResponse() []byte {
 
 	return c.ocspResponse
 }
+
+// PeerCertificates returns the certificate chain that was presented by the
+// other side.
+func (c *Conn) PeerCertificates() []*x509.Certificate {
+	c.handshakeMutex.Lock()
+	defer c.handshakeMutex.Unlock()
+
+	return c.peerCertificates
+}
diff --git a/src/pkg/crypto/tls/handshake_client.go b/src/pkg/crypto/tls/handshake_client.go
index b3b597327f..324c02f701 100644
--- a/src/pkg/crypto/tls/handshake_client.go
+++ b/src/pkg/crypto/tls/handshake_client.go
@@ -28,6 +28,7 @@ func (c *Conn) clientHandshake() os.Error {
 		compressionMethods: []uint8{compressionNone},
 		random:             make([]byte, 32),
 		ocspStapling:       true,
+		serverName:         c.config.ServerName,
 	}
 
 	t := uint32(c.config.Time())
@@ -107,6 +108,8 @@ func (c *Conn) clientHandshake() os.Error {
 		return c.sendAlert(alertUnsupportedCertificate)
 	}
 
+	c.peerCertificates = certs
+
 	if serverHello.certStatus {
 		msg, err = c.readHandshake()
 		if err != nil {
diff --git a/src/pkg/crypto/tls/handshake_messages.go b/src/pkg/crypto/tls/handshake_messages.go
index 13c05fe574..6d4e5c7094 100644
--- a/src/pkg/crypto/tls/handshake_messages.go
+++ b/src/pkg/crypto/tls/handshake_messages.go
@@ -100,7 +100,8 @@ func (m *clientHelloMsg) marshal() []byte {
 		//     ServerName server_name_list<1..2^16-1>
 		// } ServerNameList;
 
-		z[1] = 1
+		z[0] = byte((len(m.serverName) + 3) >> 8)
+		z[1] = byte(len(m.serverName) + 3)
 		z[3] = byte(len(m.serverName) >> 8)
 		z[4] = byte(len(m.serverName))
 		copy(z[5:], []byte(m.serverName))