From 65e603c1af6dd6dfbd407c6742c7b1e1bbf7b2a6 Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <nhofmeyr@sysmocom.de>
Date: Mon, 5 Sep 2022 16:02:50 +0200
Subject: [PATCH] sdp_msg: when NULL, do not crash but return empty SDP str

Change-Id: Ibd5c43fae61cd006d8fb42a06b99a609356f7037
---
 src/libmsc/sdp_msg.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/libmsc/sdp_msg.c b/src/libmsc/sdp_msg.c
index eda6ac9cc..09e127783 100644
--- a/src/libmsc/sdp_msg.c
+++ b/src/libmsc/sdp_msg.c
@@ -220,8 +220,16 @@ int sdp_msg_to_sdp_str_buf(char *dst, size_t dst_size, const struct sdp_msg *sdp
 {
 	const struct sdp_audio_codec *codec;
 	struct osmo_strbuf sb = { .buf = dst, .len = dst_size };
-	const char *ip = sdp->rtp.ip[0] ? sdp->rtp.ip : "0.0.0.0";
-	char ipv = osmo_ip_str_type(ip) == AF_INET6 ? '6' : '4';
+	const char *ip;
+	char ipv;
+
+	if (!sdp) {
+		OSMO_STRBUF_PRINTF(sb, "%s", "");
+		return sb.chars_needed;
+	}
+
+	ip = sdp->rtp.ip[0] ? sdp->rtp.ip : "0.0.0.0";
+	ipv = (osmo_ip_str_type(ip) == AF_INET6) ? '6' : '4';
 
 	OSMO_STRBUF_PRINTF(sb,
 			   "v=0\r\n"