yeah i should have done this before, i know

net/net.go

@@ -0,0 +1,98 @@
+package net
+
+import (
+	"fmt"
+	"net"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/evilsocket/bettercap/core"
+)
+
+var IPv4RouteParser = regexp.MustCompile("^([\\d\\.]+)\\s+([\\d\\.]+)\\s+([\\d\\.]+)\\s+([A-Z]+)\\s+\\d+\\s+\\d+\\s+\\d+\\s+(.+)$")
+var IPv4RouteTokens = 6
+
+func FindInterface(name string) (*Endpoint, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, iface := range ifaces {
+		mac := iface.HardwareAddr.String()
+		addrs, err := iface.Addrs()
+		// is interface active?
+		if err == nil && len(addrs) > 0 {
+			if (name == "" && iface.Name != "lo") || iface.Name == name {
+				var e *Endpoint = nil
+				// For every address of the interface.
+				for _, addr := range addrs {
+					ip := addr.String()
+					// Make sure this is an IPv4 address.
+					if m, _ := regexp.MatchString("^[0-9\\.]+/?\\d*$", ip); m == true {
+						if strings.IndexRune(ip, '/') == -1 {
+							// plain ip
+							e = NewEndpointNoResolve(ip, mac, iface.Name, 0)
+						} else {
+							// ip/bits
+							parts := strings.Split(ip, "/")
+							ip_part := parts[0]
+							bits, err := strconv.Atoi(parts[1])
+							if err == nil {
+								e = NewEndpointNoResolve(ip_part, mac, iface.Name, uint32(bits))
+							}
+						}
+					}
+				}
+
+				if e != nil {
+					return e, nil
+				}
+			}
+		}
+	}
+
+	if name == "" {
+		return nil, fmt.Errorf("Could not find default network interface.")
+	} else {
+		return nil, fmt.Errorf("Could not find interface '%s'.", name)
+	}
+}
+
+func FindGateway(iface *Endpoint) (*Endpoint, error) {
+	output, err := core.Exec("route", []string{"-n", "-A", "inet"})
+	if err != nil {
+		return nil, err
+	}
+
+	for _, line := range strings.Split(output, "\n") {
+		m := IPv4RouteParser.FindStringSubmatch(line)
+		if len(m) == IPv4RouteTokens {
+			// destination := m[1]
+			// mask := m[3]
+			flags := m[4]
+			ifname := m[5]
+
+			if ifname == iface.Name() && flags == "UG" {
+				gateway := m[2]
+				// log.Debugf("Gateway ip is %s", gateway)
+				if gateway == iface.IpAddress {
+					// log.Debug("Gateway == Interface")
+					return iface, nil
+				} else {
+					// we have the address, now we need its mac
+					mac, err := ArpLookup(iface.Name(), gateway, false)
+					if err == nil {
+						// log.Debugf("Gateway mac is %s", mac)
+						return NewEndpoint(gateway, mac), nil
+					} else {
+						log.Error(err)
+					}
+				}
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("Could not detect the gateway.")
+}