rtmp: Support 'rtmp_app', an option which overrides the name of application

This option is the name of application to connect on the RTMP server.
Sometimes the URL parser cannot determine the app name automatically,
so it must be given explicitly using this option (ie. -rtmp_app).
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rtmpproto.c

@@ -28,6 +28,7 @@
 #include "libavutil/avstring.h"
 #include "libavutil/intfloat.h"
 #include "libavutil/lfg.h"
+#include "libavutil/opt.h"
 #include "libavutil/sha.h"
 #include "avformat.h"
 #include "internal.h"
@@ -41,6 +42,8 @@
 
 //#define DEBUG
 
+#define APP_MAX_LENGTH 128
+
 /** RTMP protocol handler state */
 typedef enum {
     STATE_START,      ///< client has not done anything yet
@@ -56,12 +59,13 @@ typedef enum {
 
 /** protocol handler context */
 typedef struct RTMPContext {
+    const AVClass *class;
     URLContext*   stream;                     ///< TCP stream used in interactions with RTMP server
     RTMPPacket    prev_pkt[2][RTMP_CHANNELS]; ///< packet history used when reading and sending packets
     int           chunk_size;                 ///< size of the chunks RTMP packets are divided into
     int           is_input;                   ///< input/output flag
     char          playpath[256];              ///< path to filename to play (with possible "mp4:" prefix)
-    char          app[128];                   ///< application
+    char          *app;                       ///< name of application
     ClientState   state;                      ///< current state
     int           main_channel_id;            ///< an additional channel ID which is used for some invocations
     uint8_t*      flv_data;                   ///< buffer with data for demuxer
@@ -822,6 +826,7 @@ static int rtmp_open(URLContext *s, const char *uri, int flags)
 {
     RTMPContext *rt = s->priv_data;
     char proto[8], hostname[256], path[1024], *fname;
+    char *old_app;
     uint8_t buf[2048];
     int port;
     int ret;
@@ -847,6 +852,16 @@ static int rtmp_open(URLContext *s, const char *uri, int flags)
 
     rt->chunk_size = 128;
     rt->state = STATE_HANDSHAKED;
+
+    // Keep the application name when it has been defined by the user.
+    old_app = rt->app;
+
+    rt->app = av_malloc(APP_MAX_LENGTH);
+    if (!rt->app) {
+        rtmp_close(s);
+        return AVERROR(ENOMEM);
+    }
+
     //extract "app" part from path
     if (!strncmp(path, "/ondemand/", 10)) {
         fname = path + 10;
@@ -868,6 +883,13 @@ static int rtmp_open(URLContext *s, const char *uri, int flags)
             }
         }
     }
+
+    if (old_app) {
+        // The name of application has been defined by the user, override it.
+        av_free(rt->app);
+        rt->app = old_app;
+    }
+
     if (!strchr(fname, ':') &&
         (!strcmp(fname + strlen(fname) - 4, ".f4v") ||
          !strcmp(fname + strlen(fname) - 4, ".mp4"))) {
@@ -1013,6 +1035,22 @@ static int rtmp_write(URLContext *s, const uint8_t *buf, int size)
     return size;
 }
 
+#define OFFSET(x) offsetof(RTMPContext, x)
+#define DEC AV_OPT_FLAG_DECODING_PARAM
+#define ENC AV_OPT_FLAG_ENCODING_PARAM
+
+static const AVOption rtmp_options[] = {
+    {"rtmp_app", "Name of application to connect to on the RTMP server", OFFSET(app), AV_OPT_TYPE_STRING, {.str = NULL }, 0, 0, DEC|ENC},
+    { NULL },
+};
+
+static const AVClass rtmp_class = {
+    .class_name = "rtmp",
+    .item_name  = av_default_item_name,
+    .option     = rtmp_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 URLProtocol ff_rtmp_protocol = {
     .name           = "rtmp",
     .url_open       = rtmp_open,
@@ -1021,4 +1059,5 @@ URLProtocol ff_rtmp_protocol = {
     .url_close      = rtmp_close,
     .priv_data_size = sizeof(RTMPContext),
     .flags          = URL_PROTOCOL_FLAG_NETWORK,
+    .priv_data_class= &rtmp_class,
 };