wfd: Shorten session ID to work around buggy LG TVs

As it turns out, some TVs from LG do not accept a session ID of length
16. Subclass the session pool to change the session ID generation and
then use our own implementation rather than the default one.

Fixes: #78

src/wfd/meson.build

@@ -6,6 +6,7 @@ wfd_server_sources = [
   'wfd-params.c',
   'wfd-resolution.c',
   'wfd-server.c',
+  'wfd-session-pool.c',
   'wfd-audio-codec.c',
   'wfd-video-codec.c',
 ]

src/wfd/wfd-server.c

 #include "wfd-server.h"
 #include "wfd-client.h"
 #include "wfd-media-factory.h"
+#include "wfd-session-pool.h"
 
 struct _WfdServer
 {
@@ -23,7 +24,12 @@ static guint signals[NR_SIGNALS];
 WfdServer *
 wfd_server_new (void)
 {
-  return g_object_new (WFD_TYPE_SERVER, NULL);
+  /* We use our own session pool. The only reason to do so is
+   * to shorten the session ID to 15 characters!
+   */
+  return g_object_new (WFD_TYPE_SERVER,
+                       "session-pool", wfd_session_pool_new (),
+                       NULL);
 }
 
 static void

src/wfd/wfd-session-pool.c

+/* nd-meta-provider.c
+ *
+ * Copyright 2008 Wim Taymans <wim.taymans at gmail.com>
+ * Copyright 2018 Benjamin Berg <bberg@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "wfd-session-pool.h"
+
+struct _WfdSessionPool
+{
+  GstRTSPSessionPool parent_instance;
+};
+
+G_DEFINE_TYPE (WfdSessionPool, wfd_session_pool, GST_TYPE_RTSP_SESSION_POOL)
+
+/* The following is copied from GstRTSPSessionPool, the only change is that
+ * we stop after rather than 16 for the session-id.
+ * This is required to support some LG TVs which limit the length to 15 bytes
+ * (i.e. 16 including a NUL byte).
+ */
+static const gchar session_id_charset[] =
+    { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
+  'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D',
+  'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
+  'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7',
+  '8', '9', '-', '_', '.', '+'  /* '$' Live555 in VLC strips off $ chars */
+};
+
+static gchar*
+create_session_id (GstRTSPSessionPool * pool)
+{
+  gchar id[15];
+  gint i;
+
+  for (i = 0; i < 15; i++) {
+    id[i] =
+        session_id_charset[g_random_int_range (0,
+            G_N_ELEMENTS (session_id_charset))];
+  }
+
+  return g_strndup (id, 15);
+}
+
+static void
+wfd_session_pool_class_init (WfdSessionPoolClass *klass)
+{
+  GstRTSPSessionPoolClass *parent_class = GST_RTSP_SESSION_POOL_CLASS (klass);
+
+  parent_class->create_session_id = create_session_id;
+}
+
+static void
+wfd_session_pool_init (WfdSessionPool *self)
+{
+}
+
+WfdSessionPool *
+wfd_session_pool_new (void)
+{
+  return g_object_new (WFD_TYPE_SESSION_POOL, NULL);
+}

src/wfd/wfd-session-pool.h

+#pragma once
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#include <gst/rtsp-server/rtsp-session-pool.h>
+#pragma GCC diagnostic pop
+
+G_BEGIN_DECLS
+
+#define WFD_TYPE_SESSION_POOL (wfd_session_pool_get_type())
+
+G_DECLARE_FINAL_TYPE (WfdSessionPool, wfd_session_pool, WFD, SESSION_POOL, GstRTSPSessionPool)
+
+WfdSessionPool *wfd_session_pool_new (void);
+
+G_END_DECLS