From b6e9d7c790a9327b0bee0263308a90a8272226c4 Mon Sep 17 00:00:00 2001
From: Daniel-Constantin Mierla <miconda@gmail.com>
Date: Wed, 13 Apr 2022 11:43:17 +0200
Subject: [PATCH] sgsip: reuse via from INVITE request for ACK of failure
 responses

- GH #4
---
 sgsip/sgsip.go | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/sgsip/sgsip.go b/sgsip/sgsip.go
index c98ee33..3446029 100644
--- a/sgsip/sgsip.go
+++ b/sgsip/sgsip.go
@@ -1071,17 +1071,21 @@ func SGSIPInviteToACKString(invReq *SGSIPMessage, invRpl *SGSIPMessage, outputSt
 	for _, h := range invReq.Headers {
 		switch h.HType {
 		case HeaderTypeVia:
-			sList := strings.SplitN(h.Body, ";branch=", 2)
-			if len(sList) < 2 {
+			if invRpl.FLine.Code >= 300 {
 				sb.WriteString(h.Name + ": " + h.Body + "\r\n")
 			} else {
-				idxSCol := strings.Index(sList[1], ";")
-				if idxSCol < 0 {
-					sb.WriteString(h.Name + ": " + sList[0] + ";branch=" +
-						viaBranchCookie + uuid.New().String() + "\r\n")
+				sList := strings.SplitN(h.Body, ";branch=", 2)
+				if len(sList) < 2 {
+					sb.WriteString(h.Name + ": " + h.Body + "\r\n")
 				} else {
-					sb.WriteString(h.Name + ": " + sList[0] + ";branch=" +
-						viaBranchCookie + uuid.New().String() + sList[1][idxSCol:] + "\r\n")
+					idxSCol := strings.Index(sList[1], ";")
+					if idxSCol < 0 {
+						sb.WriteString(h.Name + ": " + sList[0] + ";branch=" +
+							viaBranchCookie + uuid.New().String() + "\r\n")
+					} else {
+						sb.WriteString(h.Name + ": " + sList[0] + ";branch=" +
+							viaBranchCookie + uuid.New().String() + sList[1][idxSCol:] + "\r\n")
+					}
 				}
 			}
 		case HeaderTypeFrom: