contrib/rtp: Enhance RTP replay tool

This patch adds optional parameters to pass the state file, the
destination address (default 127.0.0.1), the destination port
(default 4000), the source port (default 0). So it is called as
follows:

    gst rtp_replay.st -a [FILE [HOST [SOURCEPORT [DESTPORT]]]]

In addition, nonexistant FILEs are no longer created but opened
read-only instead.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/contrib/rtp/rtp_replay.st b/openbsc/contrib/rtp/rtp_replay.st
index 7fa9a4c..e26d073 100644
--- a/openbsc/contrib/rtp/rtp_replay.st
+++ b/openbsc/contrib/rtp/rtp_replay.st
@@ -7,11 +7,15 @@
 
 
 Eval [
-    | replay |
+    | replay file host dport |
 
+    file := Smalltalk arguments at: 1 ifAbsent: [ 'rtpstream.state' ].
+    host := Smalltalk arguments at: 2 ifAbsent: [ '127.0.0.1' ].
+    dport := (Smalltalk arguments at: 3 ifAbsent: [ '4000' ]) asInteger.
+    sport := (Smalltalk arguments at: 4 ifAbsent: [ '0' ]) asInteger.
 
-    replay := RTPReplay on: Smalltalk arguments first.
+    replay := RTPReplay on: file fromPort: sport.
 
     Transcript nextPutAll: 'Going to stream now'; nl.
-    replay streamAudio: '127.0.0.1' port: 4000.
+    replay streamAudio: host port: dport.
 ]