From 3eecc25d7b58229f942740e52f72e4b5c695089b Mon Sep 17 00:00:00 2001
From: Louis Royer <infos.louis.royer@gmail.com>
Date: Wed, 4 Sep 2024 18:37:50 +0200
Subject: [PATCH] Allow creation of FARMap with a FAR that have no Forwarding
 Parameter and no FORW Flag

Closes #5
---
 pfcp/far_map.go | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/pfcp/far_map.go b/pfcp/far_map.go
index 5dec9e7..386973e 100644
--- a/pfcp/far_map.go
+++ b/pfcp/far_map.go
@@ -154,26 +154,37 @@ func NewFARMap(fars []*ie.IE) (farmap *FARMap, err error, cause uint8, offending
 			}
 		}
 
-		fp, err := far.ForwardingParameters()
 		// This IE shall be present when the Apply Action requests
 		// the packets to be forwarded. It may be present otherwise.
-		if err != nil {
-			// XXX: Updating FAR should not be done like that
-			fp, err = far.UpdateForwardingParameters()
+		mustHaveFP := false
+		hasFP := false
+		if far.HasFORW() {
+			mustHaveFP = true
+		}
+		fp, err := far.ForwardingParameters()
 
+		if err != nil && mustHaveFP {
+			fp, err = far.ForwardingParameters()
 			if err != nil {
 				//XXX:  workaround for a free5gc-smf bug: Forwarding Parameters are missing sometimes
 				fp = make([]*ie.IE, 0)
+				hasFP = true
 				//			if err == io.ErrUnexpectedEOF {
 				//				return nil, err, ie.CauseInvalidLength, ie.ForwardingParameters
 				//			}
 				//			if ie.NewApplyAction(aa).HasFORW() && err == ie.ErrIENotFound {
 				//				return nil, err, ie.CauseConditionalIEMissing, ie.ForwardingParameters
 				//			}
+			} else if err == nil {
+				hasFP = true
 			}
 		}
 
-		err = f.Add(NewFAR(ie.NewFARID(id), ie.NewApplyAction(aa...), ie.NewForwardingParameters(fp...)))
+		if !hasFP {
+			err = f.Add(NewFAR(ie.NewFARID(id), ie.NewApplyAction(aa...), nil))
+		} else {
+			err = f.Add(NewFAR(ie.NewFARID(id), ie.NewApplyAction(aa...), ie.NewForwardingParameters(fp...)))
+		}
 		if err != nil {
 			return nil, err, ie.CauseMandatoryIEIncorrect, ie.CreateFAR
 		}