From 5041267be99a3f0e38f461fa96474802f968963a Mon Sep 17 00:00:00 2001
From: evilsocket <evilsocket@gmail.com>
Date: Thu, 3 May 2018 13:03:52 +0200
Subject: [PATCH] fixed net.FindGateway if there's a VPN interface active

---
 network/lan_test.go    | 13 ++-----------
 network/net_gateway.go | 29 ++++++++++++++++-------------
 network/net_test.go    | 32 --------------------------------
 3 files changed, 18 insertions(+), 56 deletions(-)

diff --git a/network/lan_test.go b/network/lan_test.go
index ce30d1ba..22a69fd4 100644
--- a/network/lan_test.go
+++ b/network/lan_test.go
@@ -1,7 +1,6 @@
 package network
 
 import (
-	"net"
 	"testing"
 )
 
@@ -14,16 +13,8 @@ func buildExampleLAN() *LAN {
 }
 
 func buildExampleEndpoint() *Endpoint {
-	ifaces, _ := net.Interfaces()
-	var exampleIface net.Interface
-	for _, iface := range ifaces {
-		if iface.HardwareAddr != nil {
-			exampleIface = iface
-			break
-		}
-	}
-	foundEndpoint, _ := FindInterface(exampleIface.Name)
-	return foundEndpoint
+	iface, _ := FindInterface("")
+	return iface
 }
 
 func TestNewLAN(t *testing.T) {
diff --git a/network/net_gateway.go b/network/net_gateway.go
index 4a47698b..ece07c74 100644
--- a/network/net_gateway.go
+++ b/network/net_gateway.go
@@ -14,21 +14,24 @@ func FindGateway(iface *Endpoint) (*Endpoint, error) {
 		return nil, err
 	}
 
+	ifName := iface.Name()
 	for _, line := range strings.Split(output, "\n") {
-		m := IPv4RouteParser.FindStringSubmatch(line)
-		if len(m) == IPv4RouteTokens {
-			return IPv4RouteIsGateway(iface.Name(), m, func(gateway string) (*Endpoint, error) {
-				if gateway == iface.IpAddress {
-					return iface, nil
-				} else {
-					// we have the address, now we need its mac
-					mac, err := ArpLookup(iface.Name(), gateway, false)
-					if err != nil {
-						return nil, err
+		if strings.Contains(line, ifName) {
+			m := IPv4RouteParser.FindStringSubmatch(line)
+			if len(m) == IPv4RouteTokens {
+				return IPv4RouteIsGateway(ifName, m, func(gateway string) (*Endpoint, error) {
+					if gateway == iface.IpAddress {
+						return iface, nil
+					} else {
+						// we have the address, now we need its mac
+						mac, err := ArpLookup(ifName, gateway, false)
+						if err != nil {
+							return nil, err
+						}
+						return NewEndpoint(gateway, mac), nil
 					}
-					return NewEndpoint(gateway, mac), nil
-				}
-			})
+				})
+			}
 		}
 	}
 
diff --git a/network/net_test.go b/network/net_test.go
index 636aed84..4d93a416 100644
--- a/network/net_test.go
+++ b/network/net_test.go
@@ -87,38 +87,6 @@ func TestFindInterfaceByName(t *testing.T) {
 	}
 }
 
-func TestMatchByAddress(t *testing.T) {
-	ifaces, err := net.Interfaces()
-	if err != nil {
-		t.Error(err)
-	}
-	if len(ifaces) <= 0 {
-		t.Error("Unable to find any network interfaces to run test with.")
-	}
-	var exampleIface net.Interface
-	// emulate libpcap's pcap_lookupdev function to find
-	// default interface to test with ( maybe could use loopback ? )
-	for _, iface := range ifaces {
-		if iface.HardwareAddr != nil {
-			exampleIface = iface
-			break
-		}
-	}
-	// check match by mac address
-	if !matchByAddress(exampleIface, exampleIface.HardwareAddr.String()) {
-		t.Error("unable to verify a match with a given interface and mac address")
-	}
-	addrs, err := exampleIface.Addrs()
-	if err != nil || len(addrs) <= 0 {
-		t.Error("Unable to find any ip addresses to run test with interface:", exampleIface.Name)
-
-	}
-	// check match by ip address
-	if !matchByAddress(exampleIface, addrs[0].String()) {
-		t.Error("unable to verify a match with a given interface and ip address")
-	}
-}
-
 func TestFindInterface(t *testing.T) {
 	ifaces, err := net.Interfaces()
 	if err != nil {