From c6740a5750adc3d6c5eb9da4d33369055cfe326f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=98=B8=EF=B8=8F?=
 <29265684+buffermet@users.noreply.github.com>
Date: Mon, 20 Sep 2021 19:18:43 +1000
Subject: [PATCH] fix automatic gateway detection for Linux

---
 routing/update_linux.go | 72 +++++++++++++++++++++++++++--------------
 1 file changed, 48 insertions(+), 24 deletions(-)

diff --git a/routing/update_linux.go b/routing/update_linux.go
index 016fe8f4..89885589 100644
--- a/routing/update_linux.go
+++ b/routing/update_linux.go
@@ -1,43 +1,67 @@
 package routing
 
 import (
-	"github.com/bettercap/bettercap/core"
-	"github.com/evilsocket/islazy/str"
 	"regexp"
 	"strings"
+
+	"github.com/bettercap/bettercap/core"
+	"github.com/evilsocket/islazy/str"
 )
 
-var parser = regexp.MustCompile(`^(.+)\sdev\s([^\s]+)\s(.+)$`)
+var (
+	routeHeadings    []string
+	whitespaceParser = regexp.MustCompile(`\s+`)
+)
 
 func update() ([]Route, error) {
 	table = make([]Route, 0)
 
-	for ip, inet := range map[RouteType]string{IPv4: "inet", IPv6: "inet6"} {
-		output, err := core.Exec("ip", []string{"-f", inet, "route"})
-		if err != nil {
-			return nil, err
-		}
+	output, err := core.Exec("netstat", []string{"-r", "-n"})
+	if err != nil {
+		return nil, err
+	}
 
-		for _, line := range strings.Split(output, "\n") {
-			if line = str.Trim(line); len(line) > 0 {
-				matches := parser.FindStringSubmatch(line)
-				if num := len(matches); num == 4 {
-					route := Route{
-						Type:        ip,
-						Destination: matches[1],
-						Device:      matches[2],
-						Flags:       matches[3],
-						Default:     strings.Index(matches[1], "default ") == 0,
-					}
+	for _, line := range strings.Split(output, "\n") {
+		if line = str.Trim(line); len(line) != 0 {
+			parts := whitespaceParser.Split(line, -1)
+			if parts[0] == "Kernel" {
+				continue
+			}
 
-					if idx := strings.Index(route.Destination, " via "); idx >= 0 {
-						route.Gateway = route.Destination[idx + len(" via "):]
-						route.Destination = route.Destination[:idx]
-					}
+			if parts[0] == "Destination" {
+				routeHeadings = parts
+				continue
+			}
 
-					table = append(table, route)
+			route := Route{}
+			for i, s := range parts {
+				switch routeHeadings[i] {
+				case "Destination":
+					route.Destination = s
+					break
+				case "Flags":
+					route.Flags = s
+					break
+				case "Gateway":
+					route.Gateway = s
+					break
+				case "Iface":
+					route.Device = s
+					break
 				}
 			}
+
+			route.Default = strings.Contains(route.Flags, "G")
+
+			if route.Destination != "" {
+				if strings.ContainsRune(route.Destination, '.') || strings.ContainsRune(route.Gateway, '.') {
+					route.Type = "IPv4"
+				} else {
+					route.Type = "IPv6"
+				}
+			}
+
+			table = append(table, route)
 		}
 	}