dynamically create client extensions offer from extensions list
Signed-off-by: Andy Green <andy@warmcat.com>
diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index ec71d79..444357b 100644
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -555,6 +555,9 @@
int okay = 0;
struct lws_tokens eff_buf;
int more = 1;
+ int ext_count = 0;
+ struct libwebsocket_extension *ext;
+
#ifdef LWS_OPENSSL_SUPPORT
char ssl_err_buf[512];
#endif
@@ -1119,8 +1122,47 @@
if (wsi->c_protocol)
p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a",
wsi->c_protocol);
- p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a",
- wsi->ietf_spec_revision);
+
+ /* tell the server what extensions we could support */
+
+ p += sprintf(p, "Sec-WebSocket-Extensions: ");
+
+ ext =context->extensions;
+ while (ext && ext->callback) {
+
+ n = 0;
+ n = context->protocols[0].callback(context, wsi,
+ LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED,
+ wsi->user_space, (char *)ext->name, 0);
+
+ /*
+ * zero return from callback means
+ * go ahead and allow the extension,
+ * it's what we get if the callback is
+ * unhandled
+ */
+
+ if (n) {
+ ext++;
+ continue;
+ }
+
+ /* apply it */
+
+ if (ext_count)
+ *p++ = ',';
+ p += sprintf(p, ext->name);
+ ext_count++;
+
+ ext++;
+ }
+
+ p += sprintf(p, "\x0d\x0a");
+
+ if (wsi->ietf_spec_revision)
+ p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a",
+ wsi->ietf_spec_revision);
+
/* give userland a chance to append, eg, cookies */
context->protocols[0].callback(context, wsi,
diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index c5ca187..3b2c11a 100644
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -64,6 +64,7 @@
LWS_CALLBACK_OPENSSL_PERFORM_CLIENT_CERT_VERIFICATION,
LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
LWS_CALLBACK_CONFIRM_EXTENSION_OKAY,
+ LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED,
/* external poll() management support */
LWS_CALLBACK_ADD_POLL_FD,
LWS_CALLBACK_DEL_POLL_FD,
@@ -334,6 +335,15 @@
* content during this callback might not be useful for anything.
* Notice this callback comes to protocols[0].
*
+ * LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED: When a client
+ * connection is being prepared to start a handshake to a server,
+ * each supported extension is checked with protocols[0] callback
+ * with this reason, giving the user code a chance to suppress the
+ * claim to support that extension by returning non-zero. If
+ * unhandled, by default 0 will be returned and the extension
+ * support included in the header to the server. Notice this
+ * callback comes to protocols[0].
+ *
* The next four reasons are optional and only need taking care of if you
* will be integrating libwebsockets sockets into an external polling
* array.
diff --git a/libwebsockets-api-doc.html b/libwebsockets-api-doc.html
index 4693387..a82383b 100644
--- a/libwebsockets-api-doc.html
+++ b/libwebsockets-api-doc.html
@@ -664,6 +664,17 @@
happened yet so if you initialize <tt><b>user</b></tt> content there, <tt><b>user</b></tt>
content during this callback might not be useful for anything.
Notice this callback comes to protocols[0].
+</blockquote>
+<h3>LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED</h3>
+<blockquote>
+When a client
+connection is being prepared to start a handshake to a server,
+each supported extension is checked with protocols[0] callback
+with this reason, giving the user code a chance to suppress the
+claim to support that extension by returning non-zero. If
+unhandled, by default 0 will be returned and the extension
+support included in the header to the server. Notice this
+callback comes to protocols[0].
<p>
The next four reasons are optional and only need taking care of if you
will be integrating libwebsockets sockets into an external polling