Added support for server name indication (RFC 4366).

Patch submitted by Kaspar Brand.

lib/gtls.c

@@ -43,6 +43,7 @@
 
 #include "urldata.h"
 #include "sendf.h"
+#include "inet_pton.h"
 #include "gtls.h"
 #include "sslgen.h"
 #include "parsedate.h"
@@ -229,6 +230,11 @@ Curl_gtls_connect(struct connectdata *conn,
   const char *ptr;
   void *ssl_sessionid;
   size_t ssl_idsize;
+#ifdef ENABLE_IPV6
+  struct in6_addr addr;
+#else
+  struct in_addr addr;
+#endif
 
   if(!gtls_inited)
     _Curl_gtls_init();
@@ -275,6 +281,15 @@ Curl_gtls_connect(struct connectdata *conn,
   /* convenient assign */
   session = conn->ssl[sockindex].session;
 
+  if ((0 == Curl_inet_pton(AF_INET, conn->host.name, &addr)) &&
+#ifdef ENABLE_IPV6
+      (0 == Curl_inet_pton(AF_INET6, conn->host.name, &addr)) &&
+#endif
+      (gnutls_server_name_set(session, GNUTLS_NAME_DNS, conn->host.name,
+                              strlen(conn->host.name)) < 0))
+    infof(data, "WARNING: failed to configure server name indication (SNI) "
+          "TLS extension\n");
+
   /* Use default priorities */
   rc = gnutls_set_default_priority(session);
   if(rc < 0)