client: add local_protocol_name binding to info

In the case you are creating a client connection, there may be
no relationship between the ws protocol you want to bind to at
the server, and the local protocol name you want the wsi to
bind to at the client.

This introduces a new client info struct member .local_protocol_name,
if it is NULL then all is as before, otherwise it binds the client
wsi to the named protocol early in the process, and .protocol is used
for the negotiation with the ws server.

This allows you to bind client wsi to local protocol handlers that
don't share the name of the ws protocol the connection will try
to negotiate.

lib/client/client-handshake.c

@@ -103,7 +103,7 @@ lws_client_connect_2(struct lws *wsi)
 	 * to whatever we decided to connect to
 	 */
 
-       lwsl_notice("%s: %p: address %s\n", __func__, wsi, ads);
+       lwsl_info("%s: %p: address %s\n", __func__, wsi, ads);
 
        n = lws_getaddrinfo46(wsi, ads, &result);
 
@@ -717,12 +717,20 @@ lws_client_connect_via_info(struct lws_client_connect_info *i)
 	struct lws *wsi;
 	int v = SPEC_LATEST_SUPPORTED;
 	const struct lws_protocols *p;
+	const char *local = i->protocol;
 
 	if (i->context->requested_kill)
 		return NULL;
 
 	if (!i->context->protocol_init_done)
 		lws_protocol_init(i->context);
+	/*
+	 * If we have .local_protocol_name, use it to select the
+	 * local protocol handler to bind to.  Otherwise use .protocol if
+	 * http[s].
+	 */
+	if (i->local_protocol_name)
+		local = i->local_protocol_name;
 
 	wsi = lws_zalloc(sizeof(struct lws), "client wsi");
 	if (wsi == NULL)
@@ -765,10 +773,19 @@ lws_client_connect_via_info(struct lws_client_connect_info *i)
 
 	wsi->protocol = &wsi->vhost->protocols[0];
 
-	/* for http[s] connection, allow protocol selection by name */
-
-	if (i->method && i->vhost && i->protocol) {
-		p = lws_vhost_name_to_protocol(i->vhost, i->protocol);
+	/*
+	 * 1) for http[s] connection, allow protocol selection by name
+	 * 2) for ws[s], if local_protocol_name given also use it for
+	 *    local protocol binding... this defeats the server
+	 *    protocol negotiation if so
+	 *
+	 * Otherwise leave at protocols[0]... the server will tell us
+	 * which protocol we are associated with since we can give it a
+	 * list.
+	 */
+	if ((i->method || i->local_protocol_name) && wsi->vhost && local) {
+		lwsl_info("binding to %s\n", local);
+		p = lws_vhost_name_to_protocol(wsi->vhost, local);
 		if (p)
 			wsi->protocol = p;
 	}

lib/client/client.c

@@ -816,7 +816,7 @@ lws_client_interpret_server_handshake(struct lws *wsi)
 
 	len = lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL);
 	if (!len) {
-		lwsl_info("lws_client_int_s_hs: WSI_TOKEN_PROTOCOL is null\n");
+		lwsl_info("%s: WSI_TOKEN_PROTOCOL is null\n", __func__);
 		/*
 		 * no protocol name to work from,
 		 * default to first protocol
@@ -842,7 +842,7 @@ lws_client_interpret_server_handshake(struct lws *wsi)
 	}
 
 	if (!okay) {
-		lwsl_err("lws_client_int_s_hs: got bad protocol %s\n", p);
+		lwsl_info("%s: got bad protocol %s\n", __func__, p);
 		cce = "HS: PROTOCOL malformed";
 		goto bail2;
 	}
@@ -851,21 +851,47 @@ lws_client_interpret_server_handshake(struct lws *wsi)
 	 * identify the selected protocol struct and set it
 	 */
 	n = 0;
-	wsi->protocol = NULL;
-	while (wsi->vhost->protocols[n].callback && !wsi->protocol) {
-		if (strcmp(p, wsi->vhost->protocols[n].name) == 0) {
+	/* keep client connection pre-bound protocol */
+	if (!(wsi->mode & LWSCM_FLAG_IMPLIES_CALLBACK_CLOSED_CLIENT_HTTP))
+		wsi->protocol = NULL;
+
+	while (wsi->vhost->protocols[n].callback) {
+		if (!wsi->protocol &&
+		    strcmp(p, wsi->vhost->protocols[n].name) == 0) {
 			wsi->protocol = &wsi->vhost->protocols[n];
 			break;
 		}
 		n++;
 	}
 
-	if (wsi->protocol == NULL) {
-		lwsl_err("lws_client_int_s_hs: fail protocol %s\n", p);
-		cce = "HS: Cannot match protocol";
-		goto bail2;
+	if (!wsi->vhost->protocols[n].callback) { /* no match */
+		/* if server, that's already fatal */
+		if (!(wsi->mode & LWSCM_FLAG_IMPLIES_CALLBACK_CLOSED_CLIENT_HTTP)) {
+			lwsl_info("%s: fail protocol %s\n", __func__, p);
+			cce = "HS: Cannot match protocol";
+			goto bail2;
+		}
+
+		/* for client, find the index of our pre-bound protocol */
+
+		n = 0;
+		while (wsi->vhost->protocols[n].callback) {
+			if (strcmp(wsi->protocol->name,
+				   wsi->vhost->protocols[n].name) == 0) {
+				wsi->protocol = &wsi->vhost->protocols[n];
+				break;
+			}
+			n++;
+		}
+
+		if (!wsi->vhost->protocols[n].callback) {
+			lwsl_err("Failed to match protocol %s\n", wsi->protocol->name);
+			goto bail2;
+		}
 	}
 
+	lwsl_debug("Selected protocol %s\n", wsi->protocol->name);
+
 check_extensions:
 	/*
 	 * stitch protocol choice into the vh protocol linked list

lib/libwebsockets.h

@@ -3321,6 +3321,13 @@ struct lws_client_connect_info {
 	const char *iface;
 	/**< NULL to allow routing on any interface, or interface name or IP
 	 * to bind the socket to */
+	const char *local_protocol_name;
+	/**< NULL: .protocol is used both to select the local protocol handler
+	 *         to bind to and as the list of remote ws protocols we could
+	 *         accept.
+	 *   non-NULL: this protocol name is used to bind the connection to
+	 *             the local protocol handler.  .protocol is used for the
+	 *             list of remote ws protocols we could accept */
 
 	/* Add new things just above here ---^
 	 * This is part of the ABI, don't needlessly break compatibility