From 5dd7202f19711228cb4a51aa8b3415421c2edefe Mon Sep 17 00:00:00 2001
From: akshay navale <akshaynawale@gmail.com>
Date: Wed, 1 Apr 2020 11:58:30 -0600
Subject: adding fallback logic to remote id parsing

Signed-off-by: akshay navale <akshaynawale@gmail.com>
---
 dhcpv6/ztpv6/parse_remote_id.go      | 27 +++++++++++++++++----------
 dhcpv6/ztpv6/parse_remote_id_test.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/dhcpv6/ztpv6/parse_remote_id.go b/dhcpv6/ztpv6/parse_remote_id.go
index 9de9bdf..9dd72b1 100644
--- a/dhcpv6/ztpv6/parse_remote_id.go
+++ b/dhcpv6/ztpv6/parse_remote_id.go
@@ -36,29 +36,36 @@ func ParseRemoteID(packet dhcpv6.DHCPv6) (*CircuitID, error) {
 		if rid := rm.Options.RemoteID(); rid != nil {
 			remoteID := string(rid.RemoteID)
 			circ, err := matchCircuitId(remoteID)
-			if err != nil {
-				return nil, err
+			if err == nil {
+				return circ, nil
+			}
+		}
+		// if we fail to find circuit id from remote id try to use interface ID option
+		if iid := rm.Options.InterfaceID(); iid != nil {
+			interfaceID := string(iid)
+			circ, err := matchCircuitId(interfaceID)
+			if err == nil {
+				return circ, nil
 			}
-			return circ, nil
 		}
 	}
-	return nil, errors.New("failed to parse RemoteID option data")
+	return nil, errors.New("failed to parse RemoteID and InterfaceID option data")
 }
 
-func matchCircuitId(remoteID string) (*CircuitID, error) {
+func matchCircuitId(circuitInfo string) (*CircuitID, error) {
 	var names, matches []string
 
 	switch {
-	case aristaPVPattern.MatchString(remoteID):
-		matches = aristaPVPattern.FindStringSubmatch(remoteID)
+	case aristaPVPattern.MatchString(circuitInfo):
+		matches = aristaPVPattern.FindStringSubmatch(circuitInfo)
 		names = aristaPVPattern.SubexpNames()
-	case aristaSMPPattern.MatchString(remoteID):
-		matches = aristaSMPPattern.FindStringSubmatch(remoteID)
+	case aristaSMPPattern.MatchString(circuitInfo):
+		matches = aristaSMPPattern.FindStringSubmatch(circuitInfo)
 		names = aristaSMPPattern.SubexpNames()
 	}
 
 	if len(matches) == 0 {
-		return nil, fmt.Errorf("no circuitId regex matches for %v", remoteID)
+		return nil, fmt.Errorf("no circuitId regex matches for %v", circuitInfo)
 	}
 
 	var circuit CircuitID
diff --git a/dhcpv6/ztpv6/parse_remote_id_test.go b/dhcpv6/ztpv6/parse_remote_id_test.go
index 48d20bc..6147cec 100644
--- a/dhcpv6/ztpv6/parse_remote_id_test.go
+++ b/dhcpv6/ztpv6/parse_remote_id_test.go
@@ -17,6 +17,7 @@ func TestCircuitID(t *testing.T) {
 		{name: "Bogus string", circuit: "ope/1/2/3:ope", fail: true, want: nil},
 		{name: "Arista Port Vlan Pattern", circuit: "Ethernet13:2001", want: &CircuitID{Port: "13", Vlan: "2001"}},
 		{name: "Arista Slot Module Port Pattern", circuit: "Ethernet1/3/4", want: &CircuitID{Slot: "1", Module: "3", Port: "4"}},
+		{name: "Arista Slot Module Port Pattern InterfaceID", circuit: "Ethernet1/3/4:default", want: &CircuitID{Slot: "1", Module: "3", Port: "4"}},
 	}
 	for _, tc := range tt {
 		t.Run(tc.name, func(t *testing.T) {
@@ -83,3 +84,34 @@ func TestParseRemoteID(t *testing.T) {
 		})
 	}
 }
+
+func TestParseRemoteIDWithInterfaceID(t *testing.T) {
+	tt := []struct {
+		name    string
+		circuit []byte
+		want    *CircuitID
+		fail    bool
+	}{
+		{name: "Bogus string", circuit: []byte("ope/1/2/3:ope.1"), fail: true, want: nil},
+		{name: "Arista Slot Module Port Pattern", circuit: []byte("Ethernet1/3/4:default"), want: &CircuitID{Slot: "1", Module: "3", Port: "4"}},
+	}
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			m := &dhcpv6.RelayMessage{
+				MessageType: dhcpv6.MessageTypeRelayForward,
+			}
+			// Has to be a well-formed relay message with the OptRelayMsg.
+			m.Options.Add(dhcpv6.OptRelayMessage(&dhcpv6.Message{}))
+			m.Options.Add(dhcpv6.OptInterfaceID(tc.circuit))
+			circuit, err := ParseRemoteID(m)
+			if err != nil && !tc.fail {
+				t.Errorf("unexpected failure: %v", err)
+			}
+			if circuit != nil {
+				require.Equal(t, *tc.want, *circuit, "ZTPRemoteID data")
+			} else {
+				require.Equal(t, tc.want, circuit, "ZTPRemoteID data")
+			}
+		})
+	}
+}
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