From 6c84978cf52dc0e463b1936e428a34a4f06ff08f Mon Sep 17 00:00:00 2001
From: Kalle Olavi Niemitalo <kon@iki.fi>
Date: Mon, 2 May 2011 14:41:40 +0300
Subject: [PATCH] 1024: Use RFC 3546 server_name TLS extension

For both GnuTLS and OpenSSL.  Not tested with nss-compat-openssl.
---
 src/network/ssl/socket.c | 18 +++++++++++++++++-
 src/network/ssl/ssl.c    | 29 ++++++++++++++++++++++++-----
 src/network/ssl/ssl.h    | 14 ++++++++++++--
 3 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/src/network/ssl/socket.c b/src/network/ssl/socket.c
index c080233fb..83c1c0710 100644
--- a/src/network/ssl/socket.c
+++ b/src/network/ssl/socket.c
@@ -181,12 +181,28 @@ int
 ssl_connect(struct socket *socket)
 {
 	int ret;
+	unsigned char *server_name;
+	struct connection *conn = socket->conn;
 
-	if (init_ssl_connection(socket) == S_SSL_ERROR) {
+	/* TODO: Recode server_name to UTF-8.  */
+	server_name = get_uri_string(conn->proxied_uri, URI_HOST);
+	if (!server_name) {
+		socket->ops->done(socket, connection_state(S_OUT_OF_MEM));
+		return -1;
+	}
+
+	/* RFC 3546 says literal IPv4 and IPv6 addresses are not allowed.  */
+	if (is_ip_address(server_name, strlen(server_name)))
+		mem_free_set(&server_name, NULL);
+
+	if (init_ssl_connection(socket, server_name) == S_SSL_ERROR) {
+		mem_free_if(server_name);
 		socket->ops->done(socket, connection_state(S_SSL_ERROR));
 		return -1;
 	}
 
+	mem_free_if(server_name);
+
 	if (socket->no_tls)
 		ssl_set_no_tls(socket);
 
diff --git a/src/network/ssl/ssl.c b/src/network/ssl/ssl.c
index 723b265e0..faf3c0844 100644
--- a/src/network/ssl/ssl.c
+++ b/src/network/ssl/ssl.c
@@ -249,13 +249,26 @@ struct module ssl_module = struct_module(
 );
 
 int
-init_ssl_connection(struct socket *socket)
+init_ssl_connection(struct socket *socket,
+		    const unsigned char *server_name)
 {
 #ifdef USE_OPENSSL
 	socket->ssl = SSL_new(context);
 	if (!socket->ssl) return S_SSL_ERROR;
+
+	/* If the server name is known, pass it to OpenSSL.
+	 *
+	 * The return value of SSL_set_tlsext_host_name is not
+	 * documented.  The source shows that it returns 1 if
+	 * successful; on error, it calls SSLerr and returns 0.  */
+	if (server_name
+	    && !SSL_set_tlsext_host_name(socket->ssl, server_name)) {
+		SSL_free(socket->ssl);
+		socket->ssl = NULL;
+		return S_SSL_ERROR;
+	}
+
 #elif defined(CONFIG_GNUTLS)
-	/* const unsigned char server_name[] = "localhost"; */
 	ssl_t *state = mem_alloc(sizeof(ssl_t));
 
 	if (!state) return S_SSL_ERROR;
@@ -294,11 +307,17 @@ init_ssl_connection(struct socket *socket)
 	/* gnutls_handshake_set_private_extensions(*state, 1); */
 	gnutls_cipher_set_priority(*state, cipher_priority);
 	gnutls_kx_set_priority(*state, kx_priority);
-	/* gnutls_certificate_type_set_priority(*state, cert_type_priority);
-	gnutls_server_name_set(*state, GNUTLS_NAME_DNS, server_name,
-			       sizeof(server_name) - 1); */
+	/* gnutls_certificate_type_set_priority(*state, cert_type_priority); */
 #endif
 
+	if (server_name
+	    && gnutls_server_name_set(*state, GNUTLS_NAME_DNS, server_name,
+				      strlen(server_name))) {
+		gnutls_deinit(*state);
+		mem_free(state);
+		return S_SSL_ERROR;
+	}
+
 	socket->ssl = state;
 #endif
 
diff --git a/src/network/ssl/ssl.h b/src/network/ssl/ssl.h
index 21ca1420b..7f89a511e 100644
--- a/src/network/ssl/ssl.h
+++ b/src/network/ssl/ssl.h
@@ -11,8 +11,18 @@ struct socket;
 extern struct module ssl_module;
 
 /* Initializes the SSL connection data. Returns S_OK on success and S_SSL_ERROR
- * on failure. */
-int init_ssl_connection(struct socket *socket);
+ * on failure.
+ *
+ * server_name is the DNS name of the server (in UTF-8), or NULL if
+ * ELinks knows only the IP address.  ELinks reports that name to the
+ * server so that the server can choose the correct certificate if it
+ * has multiple virtual hosts on the same IP address.  See RFC 3546
+ * section 3.1.
+ *
+ * server_name does not affect how ELinks verifies the certificate
+ * after the server has returned it.  */
+int init_ssl_connection(struct socket *socket,
+			const unsigned char *server_name);
 
 /* Releases the SSL connection data */
 void done_ssl_connection(struct socket *socket);