http: Do not try to make a new request when seeking past the end of the file

This avoids making invalid HTTP Range requests for a byte range past the
known end of the file during a seek. Those requests generally return a HTTP
response of 416 Range Not Satisfiable, which causes an error response.

Reference: https://tools.ietf.org/html/rfc7233

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavformat/http.c

@@ -1691,6 +1691,13 @@ static int64_t http_seek_internal(URLContext *h, int64_t off, int whence, int fo
     if (s->off && h->is_streamed)
         return AVERROR(ENOSYS);
 
+    /* do not try to make a new connection if seeking past the end of the file */
+    if (s->end_off || s->filesize != UINT64_MAX) {
+        uint64_t end_pos = s->end_off ? s->end_off : s->filesize;
+        if (s->off >= end_pos)
+            return s->off;
+    }
+
     /* we save the old context in case the seek fails */
     old_buf_size = s->buf_end - s->buf_ptr;
     memcpy(old_buf, s->buf_ptr, old_buf_size);