Make a mount point of "/" work correctly.

As far as I can tell, this is neither explicitly allowed nor
forbidden by RFC 7826.

Meanwhile, URLs such as rtsp://<IP>:554 or rtsp://<IP>:554/ are in
use in the wild (presumably with non-GStreamer servers).

GStreamer's prior behavior was confusing, in that
gst_rtsp_mount_points_add_factory() would appear to accept a mount
path of "" or "/", but later connection attempts would fail with a
"media not found" error.

This commit makes a mount path of "/" work for either form of URL,
while an empty mount path ("") is rejected and logs a warning.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-rtsp-server/-/merge_requests/168>

gst/rtsp-server/rtsp-client.c

@@ -1320,10 +1320,12 @@ default_make_path_from_uri (GstRTSPClient * client, const GstRTSPUrl * uri)
 {
   gchar *path;
 
-  if (uri->query)
+  if (uri->query) {
     path = g_strconcat (uri->abspath, "?", uri->query, NULL);
-  else
+  } else {
-    path = g_strdup (uri->abspath);
+    /* normalize rtsp://<IP>:<PORT> to rtsp://<IP>:<PORT>/ */
+    path = g_strdup (uri->abspath[0] ? uri->abspath : "/");
+  }
 
   return path;
 }
@@ -2763,9 +2765,15 @@ handle_setup_request (GstRTSPClient * client, GstRTSPContext * ctx)
     }
   } else {
     /* path is what matched. */
-    path[matched] = '\0';
+    gchar *newpath = g_strndup (path, matched);
     /* control is remainder */
-    control = &path[matched + 1];
+    if (matched == 1 && path[0] == '/')
+      control = g_strdup (&path[1]);
+    else
+      control = g_strdup (&path[matched + 1]);
+
+    g_free (path);
+    path = newpath;
 
     /* find the stream now using the control part */
     stream = gst_rtsp_media_find_stream (media, control);
@@ -2977,6 +2985,7 @@ handle_setup_request (GstRTSPClient * client, GstRTSPContext * ctx)
   g_object_unref (media);
   g_object_unref (session);
   g_free (path);
+  g_free (control);
 
   return TRUE;
 
@@ -3109,6 +3118,7 @@ keymgmt_error:
       g_object_unref (session);
   cleanup_path:
     g_free (path);
+    g_free (control);
     return FALSE;
   }
 }

gst/rtsp-server/rtsp-mount-points.c

@@ -171,7 +171,8 @@ gst_rtsp_mount_points_new (void)
 static gchar *
 default_make_path (GstRTSPMountPoints * mounts, const GstRTSPUrl * url)
 {
-  return g_strdup (url->abspath);
+  /* normalize rtsp://<IP>:<PORT> to rtsp://<IP>:<PORT>/ */
+  return g_strdup (url->abspath[0] ? url->abspath : "/");
 }
 
 /**
@@ -210,6 +211,10 @@ has_prefix (DataItem * str, DataItem * prefix)
   if (str->len < prefix->len)
     return FALSE;
 
+  /* special case when "/" is the entire prefix */
+  if (prefix->len == 1 && prefix->path[0] == '/' && str->path[0] == '/')
+    return TRUE;
+
   /* if str is larger, it there should be a / following the prefix */
   if (str->len > prefix->len && str->path[prefix->len] != '/')
     return FALSE;
@@ -331,7 +336,8 @@ gst_rtsp_mount_points_remove_factory_unlocked (GstRTSPMountPoints * mounts,
  *
  * Attach @factory to the mount point @path in @mounts.
  *
- * @path is of the form (/node)+. Any previous mount point will be freed.
+ * @path is either of the form (/node)+ or the root path '/'. (An empty path is
+ * not allowed.) Any previous mount point will be freed.
  *
  * Ownership is taken of the reference on @factory so that @factory should not be
  * used after calling this function.
@@ -345,7 +351,7 @@ gst_rtsp_mount_points_add_factory (GstRTSPMountPoints * mounts,
 
   g_return_if_fail (GST_IS_RTSP_MOUNT_POINTS (mounts));
   g_return_if_fail (GST_IS_RTSP_MEDIA_FACTORY (factory));
-  g_return_if_fail (path != NULL);
+  g_return_if_fail (path != NULL && path[0] == '/');
 
   priv = mounts->priv;
 
@@ -374,7 +380,7 @@ gst_rtsp_mount_points_remove_factory (GstRTSPMountPoints * mounts,
   GstRTSPMountPointsPrivate *priv;
 
   g_return_if_fail (GST_IS_RTSP_MOUNT_POINTS (mounts));
-  g_return_if_fail (path != NULL);
+  g_return_if_fail (path != NULL && path[0] == '/');
 
   priv = mounts->priv;
 

gst/rtsp-server/rtsp-session-media.c

@@ -194,6 +194,12 @@ gst_rtsp_session_media_matches (GstRTSPSessionMedia * media,
   if (len < priv->path_len)
     return FALSE;
 
+  /* special case when "/" is the entire path */
+  if (priv->path_len == 1 && priv->path[0] == '/' && path[0] == '/') {
+    *matched = 1;
+    return TRUE;
+  }
+
   /* if media path is larger, it there should be a / following the path */
   if (len > priv->path_len && path[priv->path_len] != '/')
     return FALSE;