From d370fe05f5884691a89784aa73bfb4eb2176edab Mon Sep 17 00:00:00 2001
From: Julien Barbot <julien@barbot.org>
Date: Sun, 3 Nov 2013 21:30:03 +0100
Subject: Add a new server_name_indication option to ssl:connect

- Set to disable to explicitly disable SNI support.
- Set to a hostname when upgrading from TCP to TLS.
---
 lib/ssl/doc/src/ssl.xml       | 10 +++++++++-
 lib/ssl/src/ssl_handshake.erl | 18 ++++++++++++------
 lib/ssl/src/ssl_internal.hrl  |  3 ++-
 lib/ssl/src/tls.erl           |  9 ++++++++-
 4 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/lib/ssl/doc/src/ssl.xml b/lib/ssl/doc/src/ssl.xml
index aac04095b4..b4182e6d61 100644
--- a/lib/ssl/doc/src/ssl.xml
+++ b/lib/ssl/doc/src/ssl.xml
@@ -89,7 +89,7 @@
       {ssl_imp, ssl_imp()} | {reuse_sessions, boolean()} | {reuse_session, fun()}
       {next_protocols_advertised, [binary()]} |
       {client_preferred_next_protocols, {client | server, [binary()]} | {client | server, [binary()], binary()}} |
-      {log_alert, boolean()}
+      {log_alert, boolean()} | {server_name_indication, hostname() | disable}
     </c></p>
 
     <p><c>transportoption() = {cb_info, {CallbackModule::atom(), DataTag::atom(), ClosedTag::atom(), ErrTag:atom()}}
@@ -384,6 +384,14 @@ fun(srp, Username :: string(), UserState :: term()) ->
       <tag>{srp_identity, {Username :: string(), Password :: string()}</tag>
       <item>Specifies the Username and Password to use to authenticate to the server.
       </item>
+      <tag>{server_name_indication, hostname()}</tag>
+      <tag>{server_name_indication, disable}</tag>
+      <item>
+        <p>This option can be specified when upgrading a tcp socket to a tls
+        socket to use the TLS Server Name Indication extension.</p>
+        <p>This option can also be set to disable to explicitly disable usage of
+        the Server Name Indication extension.</p>
+      </item>
     </taglist>
    </section>
 
diff --git a/lib/ssl/src/ssl_handshake.erl b/lib/ssl/src/ssl_handshake.erl
index e1fd6970cc..9142a260b1 100644
--- a/lib/ssl/src/ssl_handshake.erl
+++ b/lib/ssl/src/ssl_handshake.erl
@@ -105,7 +105,7 @@ client_hello_extensions(Host, Version, CipherSuites, SslOpts, ConnectionStates,
        next_protocol_negotiation =
 	   encode_client_protocol_negotiation(SslOpts#ssl_options.next_protocol_selector,
 					      Renegotiation),
-       sni = sni(Host)}.
+       sni = sni(Host, SslOpts#ssl_options.server_name_indication)}.
 
 %%--------------------------------------------------------------------
 -spec certificate(der_cert(), db_handle(), certdb_ref(), client | server) -> #certificate{} | #alert{}.
@@ -1159,13 +1159,19 @@ select_curve(Curves, [Curve| Rest]) ->
 	false ->
 	    select_curve(Curves, Rest)
     end.
+%% RFC 6066, Section 3: Currently, the only server names supported are
+%% DNS hostnames
+sni(_, disable) ->
+    undefined;
+sni(Host, undefined) ->
+    sni1(Host);
+sni(_Host, SNIOption) ->
+    sni1(SNIOption).
 
-sni(Host) ->
-    %% RFC 6066, Section 3: Currently, the only server names supported are
-    %% DNS hostnames
-    case inet_parse:domain(Host) of
+sni1(Hostname) ->
+    case inet_parse:domain(Hostname) of
         false -> undefined;
-        true -> #sni{hostname = Host}
+        true -> #sni{hostname = Hostname}
     end.
 %%--------------------------------------------------------------------
 %%% Internal functions
diff --git a/lib/ssl/src/ssl_internal.hrl b/lib/ssl/src/ssl_internal.hrl
index 96e3280fb5..a582b8c290 100644
--- a/lib/ssl/src/ssl_internal.hrl
+++ b/lib/ssl/src/ssl_internal.hrl
@@ -115,7 +115,8 @@
 	  erl_dist = false,
 	  next_protocols_advertised = undefined, %% [binary()],
 	  next_protocol_selector = undefined,  %% fun([binary()]) -> binary())
-	  log_alert
+	  log_alert,
+	  server_name_indication = undefined
 	  }).
 
 -record(socket_options,
diff --git a/lib/ssl/src/tls.erl b/lib/ssl/src/tls.erl
index b220a48f73..f1747dc69e 100644
--- a/lib/ssl/src/tls.erl
+++ b/lib/ssl/src/tls.erl
@@ -664,7 +664,8 @@ handle_options(Opts0, _Role) ->
       next_protocol_selector = 
 			make_next_protocol_selector(
 			  handle_option(client_preferred_next_protocols, Opts, undefined)),
-      log_alert = handle_option(log_alert, Opts, true)
+      log_alert = handle_option(log_alert, Opts, true),
+      server_name_indication = handle_option(server_name_indication, Opts, undefined)
      },
 
     CbInfo  = proplists:get_value(cb_info, Opts, {gen_tcp, tcp, tcp_closed, tcp_error}),    
@@ -855,6 +856,12 @@ validate_option(next_protocols_advertised = Opt, Value) when is_list(Value) ->
 
 validate_option(next_protocols_advertised, undefined) ->
     undefined;
+validate_option(server_name_indication, Value) when is_list(Value) ->
+    Value;
+validate_option(server_name_indication, disable) ->
+    disable;
+validate_option(server_name_indication, undefined) ->
+    undefined;
 validate_option(Opt, Value) ->
     throw({error, {options, {Opt, Value}}}).
 
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