ff_url_join: Don't add any at-char if the auth is an empty string

Originally committed as revision 23650 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/internal.h

@@ -131,7 +131,8 @@ void ff_url_split(char *proto, int proto_size,
  * @param size the size of the str buffer
  * @param proto the protocol identifier, if null, the separator
  *              after the identifier is left out, too
- * @param authorization an optional authorization string, may be null
+ * @param authorization an optional authorization string, may be null.
+ *                      An empty string is treated the same as a null string.
  * @param hostname the host name string
  * @param port the port number, left out from the string if negative
  * @param fmt a generic format string for everything to add after the

libavformat/utils.c

@@ -3601,7 +3601,7 @@ int ff_url_join(char *str, int size, const char *proto,
     str[0] = '\0';
     if (proto)
         av_strlcatf(str, size, "%s://", proto);
-    if (authorization)
+    if (authorization && authorization[0])
         av_strlcatf(str, size, "%s@", authorization);
 #if CONFIG_NETWORK && defined(AF_INET6)
     /* Determine if hostname is a numerical IPv6 address,