server: add websockets support via libwebsockets

New API: spice_server_set_ws_ports

This adds an optional dependency on libwebsockets. You need to get my
patched 0.0.3 version here:
 git://people.freedesktop.org/~alon/libwebsockets

There is no qemu patches yet, to test change in reds.c the default value
of spice_ws_port to 5959 (for the default of spice-html5).

For testing there is an online client at
 http://spice-space.org/spice-html5/spice.html

Known issues:
 1. The tester (server/tests/test_display_no_ssl) gets into dropping all
  data after a few seconds, I think it's an issue with the implemented
  watches, but haven't figured it out.

 2. libwebsocket's read interface is inverted to what our code expects,
 i.e. there is no libwebsocket_read, so there is an additional copy
 involved (see RedsWebSocket). This can be fixed.

 3. Listening on a separate port. Since the headers are different, we
 could listen on the same port (first three bytes RED/GET). I don't know
 if we want to?

Todos:
 1. SSL not implemented yet. Needs some thought as to how.

 2. Serve spice-html5 when accessed as a http server. Nice to have.

1 files changed, 17 insertions, 0 deletions

diff --git a/server/reds.h b/server/reds.h
index f8e8d56c..0d4f933c 100644
--- a/server/reds.h
+++ b/server/reds.h
@@ -65,6 +65,20 @@ typedef struct RedsSASL {
 } RedsSASL;
 #endif
 
+#ifdef USE_LIBWEBSOCKETS
+typedef struct RedsWebSocket {
+    struct libwebsocket_context *context;
+    struct libwebsocket *wsi;
+    SpiceWatch *watch;
+    int fd;
+    unsigned events;
+    /* buffer of available data to read, always starts at offset 0 to data_avail - 1. */
+    unsigned char *data;
+    unsigned data_len;
+    unsigned data_avail;
+} RedsWebSocket;
+#endif
+
 struct RedsStream {
     int socket;
     SpiceWatch *watch;
@@ -73,6 +87,9 @@ struct RedsStream {
        receive may return data afterward. check the flag before calling receive*/
     int shutdown;
     SSL *ssl;
+#ifdef USE_LIBWEBSOCKETS
+    RedsWebSocket *ws;
+#endif
 
 #if HAVE_SASL
     RedsSASL sasl;