stream_filter: httplive.c: parse attributes in #EXT-<tag> tags.

Implement an attribute parsing function that does not depend on fixed position of attributes in a HTTP live streaming m3u8 file.
The function returns a copy of the attributes value. Do not forget to free the copy otherwise it will result in a memory leak.

modules/stream_filter/httplive.c

@@ -76,7 +76,7 @@ typedef struct hls_stream_s
 {
     int         id;         /* program id */
     uint64_t    bandwidth;  /* bandwidth usage of segments (kbps)*/
-    int         version;
+    int         version;    /* protocol version should be 1 */
     int         sequence;   /* media sequence number */
     uint64_t    duration;   /* maximum duration per segment (ms) */
     int         segment;    /* current segment downloading */
@@ -525,6 +525,37 @@ static inline void FreeAllSegments(hls_stream_t *hls)
 }
 
 /* Parsing */
+static char *parse_Attributes(const char *line, const char *attr)
+{
+    char *p;
+    char *begin = (char *) line;
+    char *end = begin + strlen(line);
+
+    /* Find start of attributes */
+    if ((p = strchr(begin, ':' )) == NULL)
+        return NULL;
+
+    begin = p;
+    do
+    {
+        if (strncasecmp(begin, attr, strlen(attr)) == 0)
+        {
+            /* <attr>=<value>[,]* */
+            p = strchr(begin, ',');
+            begin += strlen(attr) + 1;
+            if (begin >= end)
+                return NULL;
+            if (p == NULL) /* last attribute */
+                return strndup(begin, end - begin);
+            /* copy till ',' */
+            return strndup(begin, p - begin);
+        }
+        begin++;
+    } while(begin < end);
+
+    return NULL;
+}
+
 static void parse_SegmentInformation(stream_t *s, hls_stream_t *hls, char *p_read, char *uri)
 {
     stream_sys_t *p_sys = s->p_sys;
@@ -535,7 +566,7 @@ static void parse_SegmentInformation(stream_t *s, hls_stream_t *hls, char *p_rea
     int ret = sscanf(p_read, "#EXTINF:%d,", &duration);
     if (ret != 1)
     {
-        msg_Err(s, "Parsing #EXTINF:<s>,");
+        msg_Err(s, "expected #EXTINF:<s>,");
         p_sys->b_error = true;
     }
     else
@@ -557,7 +588,7 @@ static void parse_TargetDuration(stream_t *s, char *p_read)
     int ret = sscanf(p_read, "#EXT-X-TARGETDURATION:%d", &duration);
     if (ret != 1)
     {
-        msg_Err(s, "Parsing #EXT-X-TARGETDURATION:<s>");
+        msg_Err(s, "expected #EXT-X-TARGETDURATION:<s>");
         p_sys->b_error = true;
     }
     else
@@ -575,41 +606,56 @@ static void parse_StreamInformation(stream_t *s, char *p_read, char *uri)
 {
     stream_sys_t *p_sys = s->p_sys;
 
-    /* FIXME: proper attribute parsing
-     * The current method only parses the most common attribute ordering, but
-     * does not allow other ordering. The specification does not specify the
-     * exact attribute ordering. */
     int id, bw;
-    int ret = sscanf(p_read, "#EXT-X-STREAM-INF:PROGRAM-ID=%d,BANDWIDTH=%d", &id, &bw);
-    if (ret != 2)
+    char *attr;
+
+    attr = parse_Attributes(p_read, "PROGRAM-ID");
+    if (attr == NULL)
     {
-        msg_Err(s, "error parsing: #EXT-X-STREAM-INF, ignoring ...");
+        msg_Err(s, "#EXT-X-STREAM-INF: expected PROGRAM-ID=<value>");
         p_sys->b_error = true;
+        return;
     }
-    else
+    id = atol(attr);
+    free(attr);
+
+    attr = parse_Attributes(p_read, "BANDWIDTH");
+    if (attr == NULL)
     {
-        msg_Info(s, "Bandwidth adaption detected (program-id=%d, bandwidth=%d).", id, bw);
+        msg_Err(s, "#EXT-X-STREAM-INF: expected BANDWIDTH=<value>");
+        p_sys->b_error = true;
+        return;
+    }
+    bw = atoll(attr);
+    free(attr);
+
+    if (bw == 0)
+    {
+        msg_Err(s, "#EXT-X-STREAM-INF: bandwidth cannot be 0");
+        p_sys->b_error = true;
+        return;
+    }
+
+    msg_Info(s, "Bandwidth adaption detected (program-id=%d, bandwidth=%d).", id, bw);
 
 #if 1
-        /* FIXME: WORKAROUND FOR BUG IN ANEVIA m3u8 */
-        char *psz_uri = NULL;
-        if (asprintf(&psz_uri,"http://%s/%s","demo.anevia.com/0", uri) == -1)
-        {
-            msg_Err(s, "Failed workaround");
-            p_sys->b_error = true;
-        }
+    /* FIXME: WORKAROUND FOR BUG IN ANEVIA m3u8 */
+    char *psz_uri = NULL;
+    if (asprintf(&psz_uri,"http://%s/%s","demo.anevia.com/0", uri) == -1)
+    {
+        msg_Err(s, "Failed workaround");
+        p_sys->b_error = true;
+    }
 #endif
-        if (psz_uri != NULL)
-        {
-            msg_Info(s, "Playlist Location: %s", psz_uri);
 
-            hls_stream_t *hls = hls_New(p_sys->hls_stream, id, bw, psz_uri);
-            if (hls == NULL)
-            {
-                free(psz_uri);
-                msg_Err(s, "Could not allocate new HTTP Live Stream.");
-                p_sys->b_error = true;
-            }
+    if (psz_uri != NULL)
+    {
+        hls_stream_t *hls = hls_New(p_sys->hls_stream, id, bw, psz_uri);
+        if (hls == NULL)
+        {
+            free(psz_uri);
+            msg_Err(s, "Could not allocate new HTTP Live Stream.");
+            p_sys->b_error = true;
         }
     }
 }
@@ -622,7 +668,7 @@ static void parse_MediaSequence(stream_t *s, char *p_read)
     int ret = sscanf(p_read, "#EXT-X-MEDIA-SEQUENCE:%d", &sequence);
     if (ret != 1)
     {
-        msg_Err(s, "Parsing #EXT-X-MEDIA-SEQUENCE:<s>");
+        msg_Err(s, "expected #EXT-X-MEDIA-SEQUENCE:<s>");
         p_sys->b_error = true;
     }
     else
@@ -644,10 +690,34 @@ static void parse_MediaSequence(stream_t *s, char *p_read)
 static void parse_Key(stream_t *s, char *p_read)
 {
     stream_sys_t *p_sys = s->p_sys;
-    VLC_UNUSED(p_read);
 
-    msg_Warn(s, "Playback of encrypted HTTP Live Streaming media is not supported.");
-    p_sys->b_error = true;
+    /* #EXT-X-KEY:METHOD=<method>[,URI="<URI>"][,IV=<IV>] */
+    char *attr;
+    attr = parse_Attributes(p_read, "METHOD");
+    if (attr == NULL)
+    {
+        msg_Err(s, "#EXT-X-KEY: expected METHOD=<value>");
+        p_sys->b_error = true;
+    }
+    else if (strncasecmp(attr, "NONE", 4) == 0)
+    {
+        char *uri = parse_Attributes(p_read, "URI");
+        char *iv = parse_Attributes(p_read, "IV");
+        if ((iv != NULL) || (uri != NULL))
+        {
+            msg_Err(s, "#EXT-X-KEY: URI and IV not expected");
+            p_sys->b_error = true;
+
+            free(iv);
+            free(uri);
+        }
+    }
+    else
+    {
+        msg_Warn(s, "Playback of encrypted HTTP Live Streaming media is not supported.");
+        p_sys->b_error = true;
+    }
+    free(attr);
 }
 
 static void parse_ProgramDateTime(stream_t *s, char *p_read)
@@ -663,7 +733,7 @@ static void parse_AllowCache(stream_t *s, char *p_read)
     int ret = sscanf(p_read, "#EXT-X-ALLOW-CACHE:%3s", answer);
     if (ret != 1)
     {
-        msg_Err(s, "error parsing: #EXT-X-ALLOW-CACHE, ignoring ...");
+        msg_Err(s, "#EXT-X-ALLOW-CACHE, ignoring ...");
         p_sys->b_error = true;
     }
     else
@@ -682,15 +752,21 @@ static void parse_Version(stream_t *s, char *p_read)
     int ret = sscanf(p_read, "#EXT-X-VERSION:%d", &version);
     if (ret != 1)
     {
-        msg_Err(s, "error parsing: #EXT-X-VERSION, defaulting to protocol version 1.");
+        msg_Err(s, "#EXT-X-VERSION: no protocol version found, should be version 1.");
         p_sys->b_error = true;
+        return;
     }
-    else
+
+    hls_stream_t *hls = hls_GetLast(p_sys->hls_stream);
+    if (hls)
     {
-        hls_stream_t *hls = hls_GetLast(p_sys->hls_stream);
-        if (hls)
-            hls->version = version;
-        /* FIXME: check if this version is supported else abort */
+        hls->version = version;
+        /* Check version */
+        if (hls->version != 1)
+        {
+            msg_Err(s, "#EXT-X-VERSION should be version 1 iso %d", version);
+            p_sys->b_error = true;
+        }
     }
 }