From 2734e1c38cf30094cbb8b24025031ced8396d92b Mon Sep 17 00:00:00 2001
From: Pau Espin Pedrol <pespin@sysmocom.de>
Date: Thu, 16 Jan 2020 19:44:47 +0100
Subject: sccp: Support receiving messages with no optional params

Change-Id: I745bd32c62763ba2d88e74de8644c171ef506b37
---
 src/sccp2sua.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/sccp2sua.c b/src/sccp2sua.c
index b829cf6..2be27ea 100644
--- a/src/sccp2sua.c
+++ b/src/sccp2sua.c
@@ -705,6 +705,12 @@ static struct xua_msg *sccp_to_xua_opt(struct msgb *msg, uint8_t *ptr_opt, struc
 	/* some bounds checking */
 	if (ptr_opt < msg->data || ptr_opt > msg->tail)
 		return NULL;
+
+	/* Q.713 section 2.3 "Coding of pointers": pointer value all zeros used
+	  to indicate that no optional param is present. */
+	if (*ptr_opt == 0)
+		return xua;
+
 	opt_start = ptr_opt + *ptr_opt;
 	if (opt_start > msg->tail)
 		return NULL;
-- 
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