From b562f5ca477bde2a48f6aad35e7cdc7da9a7f276 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Mon, 23 Feb 2026 10:12:55 -0400
Subject: [PATCH] MT#55283 extend "answer only" logic

Provide an extra codec-store for the lookup of the answer codec. This is
needed for codec switches during an extra answer, as the original codecs
are kept in a different codec-store.

Closes #2073

Change-Id: I7e2efc434789ecc8d3b5fcf97240e5c3f7c84652
(cherry picked from commit cfe9a588fac393444edaf460076ff394ad255227)
---
 daemon/call.c   | 15 ++++++++-------
 daemon/codec.c  |  9 ++++++---
 include/codec.h |  4 ++--
 3 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/daemon/call.c b/daemon/call.c
index ef8f42666..dd7717d26 100644
--- a/daemon/call.c
+++ b/daemon/call.c
@@ -2540,21 +2540,21 @@ static void codecs_answer(struct call_media *media, struct call_media *other_med
 			STR_FMT(&other_media->monologue->tag),
 			other_media->index);
 
-	bool codec_answer_only = true;
+	const struct codec_store *answer_cs = &media->offered_codecs;
 	// don't do codec answer for a rejected media section
 	if (other_media->streams.length == 0)
-		codec_answer_only = false;
+		answer_cs = NULL;
 	else if (sp->rtp_endpoint.port == 0)
-		codec_answer_only = false;
+		answer_cs = NULL;
 
 	if (flags->reuse_codec)
 		codec_store_populate_reuse(&other_media->codecs, &sp->codecs,
 				.codec_set = flags->codec_set,
-				.answer_only = codec_answer_only);
+				.answer_cs = answer_cs);
 	else
 		codec_store_populate(&other_media->codecs, &sp->codecs,
 				.codec_set = flags->codec_set,
-				.answer_only = codec_answer_only,
+				.answer_cs = answer_cs,
 				.allow_asymmetric = !!flags->allow_asymmetric_codecs);
 	codec_store_strip(&other_media->codecs, &flags->codec_strip, flags->codec_except);
 	codec_store_offer(&other_media->codecs, &flags->codec_offer, &sp->codecs);
@@ -4577,12 +4577,13 @@ int monologue_subscribe_answer(struct call_monologue *dst_ml, sdp_ng_flags *flag
 		if (flags->allow_transcoding) {
 			codec_store_populate(&dst_media->codecs, &sp->codecs,
 					.codec_set = flags->codec_set,
-					.answer_only = true,
+					.answer_cs = &src_media->codecs,
 					.allow_asymmetric = !!flags->allow_asymmetric_codecs);
 			codec_store_strip(&dst_media->codecs, &flags->codec_strip, flags->codec_except);
 			codec_store_offer(&dst_media->codecs, &flags->codec_offer, &sp->codecs);
 		} else {
-			codec_store_populate(&dst_media->codecs, &sp->codecs, .answer_only = true,
+			codec_store_populate(&dst_media->codecs, &sp->codecs,
+					.answer_cs = &src_media->codecs,
 					.allow_asymmetric = !!flags->allow_asymmetric_codecs);
 			if (!codec_store_is_full_answer(&src_media->codecs, &dst_media->codecs))
 				return -1;
diff --git a/daemon/codec.c b/daemon/codec.c
index 24e201d95..0e971fe03 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -5676,7 +5676,7 @@ void __codec_store_populate_reuse(struct codec_store *dst, struct codec_store *s
 			codec_store_add_raw_link(dst, dup, pos);
 		}
 		else {
-			if (!a.answer_only) {
+			if (!a.answer_cs) {
 				ilogs(codec, LOG_DEBUG, "Adding codec " STR_FORMAT "/" STR_FORMAT
 					" (%i) to end of list",
 						STR_FMT(&pt->encoding_with_params),
@@ -5756,8 +5756,11 @@ void __codec_store_populate(struct codec_store *dst, struct codec_store *src, st
 				GINT_TO_POINTER(pt->payload_type));
 		if (orig_pt && !rtp_payload_type_eq_compat(orig_pt, pt))
 			orig_pt = NULL;
-		if (a.answer_only && !orig_pt) {
-			if (a.allow_asymmetric)
+		if (a.answer_cs && !orig_pt) {
+			orig_pt = t_hash_table_lookup(a.answer_cs->codecs, GINT_TO_POINTER(pt->payload_type));
+			if (orig_pt && !rtp_payload_type_eq_compat(orig_pt, pt))
+				orig_pt = NULL;
+			if (a.allow_asymmetric && !orig_pt)
 				orig_pt = codec_store_find_compatible(&orig_dst, pt);
 			if (!orig_pt) {
 				ilogs(codec, LOG_DEBUG, "Not adding stray answer codec "
diff --git a/include/codec.h b/include/codec.h
index 53776a0cd..9bd7306f3 100644
--- a/include/codec.h
+++ b/include/codec.h
@@ -164,9 +164,9 @@ void codec_update_all_source_handlers(struct call_monologue *ml, const sdp_ng_fl
 
 struct codec_store_args {
 	str_case_value_ht codec_set;
-	bool answer_only;
-	bool allow_asymmetric;
+	const struct codec_store *answer_cs;
 	struct codec_store *merge_cs;
+	bool allow_asymmetric;
 };
 
 __attribute__((nonnull(1)))