TT#30403 support codec-offer

only codecs from the original list for now

Change-Id: I884775a5b337ed3533972f4361ecb50e329b126e

README.md

@@ -1193,6 +1193,19 @@ Optionally included keys are:
 		an `a=rtpmap` attribute, or can be from the list of RFC-defined codecs. Examples
 		are `PCMU`, `opus`, or `telephone-event`.
 
+		As a special keyword, `all` can be used to remove all codecs, except the ones
+		that should explicitly offered (see below). Note that it is an error to strip
+		all codecs and leave none that could be offered. In this case, the original
+		list of codecs will be left unchanged.
+
+	* `offer`
+
+		Contains a list of strings. Each string is the name of a codec that should be
+		included in the list of codecs offered. This is primarily useful to block all
+		codecs (`strip -> all`) except the ones given in the `offer` whitelist.
+		Currently codecs that were not present in the original list of codecs
+		offered by the client will be ignored.
+
 
 An example of a complete `offer` request dictionary could be (SDP body abbreviated):
 

daemon/call.c

@@ -1419,32 +1419,56 @@ static void __dtls_logic(const struct sdp_ng_flags *flags,
 		MEDIA_SET(other_media, DTLS);
 }
 
-static void __rtp_payload_types(struct call_media *media, GQueue *types, GHashTable *strip) {
-	struct rtp_payload_type *pt;
+static void __rtp_payload_type_add(struct call_media *media, struct rtp_payload_type *pt) {
 	struct call *call = media->call;
-	static const str __all = STR_CONST_INIT("all");
+	/* we must duplicate the contents */
+	call_str_cpy(call, &pt->encoding_with_params, &pt->encoding_with_params);
+	call_str_cpy(call, &pt->encoding, &pt->encoding);
+	call_str_cpy(call, &pt->encoding_parameters, &pt->encoding_parameters);
+	call_str_cpy(call, &pt->format_parameters, &pt->format_parameters);
+	g_hash_table_replace(media->rtp_payload_types, &pt->payload_type, pt);
+	g_queue_push_tail(&media->rtp_payload_types_prefs, pt);
+}
+
+static void __rtp_payload_types(struct call_media *media, GQueue *types, GHashTable *strip,
+		const GQueue *offer)
+{
+	struct rtp_payload_type *pt;
+	static const str str_all = STR_CONST_INIT("all");
+	GHashTable *removed = g_hash_table_new_full(str_hash, str_equal, NULL, __payload_type_free);
+	int remove_all = 0;
 
 	// start fresh
 	g_queue_clear(&media->rtp_payload_types_prefs);
 
+	if (strip && g_hash_table_lookup(strip, &str_all))
+		remove_all = 1;
+
 	/* we steal the entire list to avoid duplicate allocs */
 	while ((pt = g_queue_pop_head(types))) {
 		// codec stripping
 		if (strip) {
-			if (g_hash_table_lookup(strip, &pt->encoding)
-					|| g_hash_table_lookup(strip, &__all)) {
-				__payload_type_free(pt);
+			if (remove_all || g_hash_table_lookup(strip, &pt->encoding)) {
+				g_hash_table_replace(removed, &pt->encoding, pt);
 				continue;
 			}
 		}
-		/* we must duplicate the contents */
-		call_str_cpy(call, &pt->encoding_with_params, &pt->encoding_with_params);
-		call_str_cpy(call, &pt->encoding, &pt->encoding);
-		call_str_cpy(call, &pt->encoding_parameters, &pt->encoding_parameters);
-		call_str_cpy(call, &pt->format_parameters, &pt->format_parameters);
-		g_hash_table_replace(media->rtp_payload_types, &pt->payload_type, pt);
-		g_queue_push_tail(&media->rtp_payload_types_prefs, pt);
+		__rtp_payload_type_add(media, pt);
+	}
+
+	if (offer) {
+		// now restore codecs that have been removed, but should be offered
+		for (GList *l = offer->head; l; l = l->next) {
+			str *codec = l->data;
+			pt = g_hash_table_lookup(removed, codec);
+			if (!pt)
+				continue;
+			g_hash_table_steal(removed, codec);
+			__rtp_payload_type_add(media, pt);
+		}
 	}
+
+	g_hash_table_destroy(removed);
 }
 
 static void __ice_start(struct call_media *media) {
@@ -1567,7 +1591,7 @@ int monologue_offer_answer(struct call_monologue *other_ml, GQueue *streams,
 				MEDIA_SET(other_media, SDES);
 		}
 
-		__rtp_payload_types(media, &sp->rtp_payload_types, flags->codec_strip);
+		__rtp_payload_types(media, &sp->rtp_payload_types, flags->codec_strip, &flags->codec_offer);
 
 		/* send and recv are from our POV */
 		bf_copy_same(&media->media_flags, &sp->sp_flags,

utils/rtpengine-ng-client

@@ -45,6 +45,7 @@ GetOptions(
 	'port-latching'			=> \$options{'port latching'},
 	'media-address=s'		=> \$options{'media address'},
 	'codec-strip=s@'		=> \$options{'codec-strip'},
+	'codec-offer=s@'		=> \$options{'codec-offer'},
 	'flags=s@'			=> \$options{'flags'},
 ) or die;
 
@@ -75,6 +76,9 @@ if (defined($options{direction})) {
 if ($options{'codec-strip'} && @{$options{'codec-strip'}}) {
 	$packet{codec}{strip} = $options{'codec-strip'};
 }
+if ($options{'codec-offer'} && @{$options{'codec-offer'}}) {
+	$packet{codec}{offer} = $options{'codec-offer'};
+}
 if ($options{'flags'} && @{$options{'flags'}}) {
 	push(@{$packet{flags}}, @{$options{'flags'}});
 }