Add local ip template

README.md

@@ -140,6 +140,7 @@ Almost every leaf `[string]` or `[object]` parameter can be templated with go te
 - `random_payload`
 - `random_mac_addr`
 - `random_port`
+- `local_ip`
 - `base64_encode`
 - `base64_decode`
 

main.go

@@ -94,9 +94,11 @@ func parseStringTemplate(input string) string {
 		"random_ip":       packetgen.RandomIP,
 		"random_port":     packetgen.RandomPort,
 		"random_mac_addr": packetgen.RandomMacAddr,
+		"local_ip":        packetgen.LocalIP,
 		"base64_encode":   base64.StdEncoding.EncodeToString,
 		"base64_decode":   base64.StdEncoding.DecodeString,
 		"json_encode":     json.Marshal,
+		"json_decode":     json.Unmarshal,
 	}
 	// TODO: consider adding ability to populate custom data
 	tmpl, err := template.New("test").Funcs(funcMap).Parse(input)
@@ -340,12 +342,19 @@ func packetgenJob(ctx context.Context, l *logs.Logger, args JobArgs) error {
 
 	for jobConfig.Next(ctx) {
 		packetConfigBytes := parseByteTemplate(jobConfig.Packet)
+		l.Debug("[packetgen] parsed packet config template:\n%s", string(packetConfigBytes))
 		var packetConfig packetgen.PacketConfig
 		err := json.Unmarshal(packetConfigBytes, &packetConfig)
 		if err != nil {
 			l.Error("error parsing json: %v", err)
 			return err
 		}
+		packetConfigBytes, err = json.Marshal(packetConfig)
+		if err != nil {
+			l.Error("error marshaling back to json: %v", err)
+			return err
+		}
+		l.Debug("[packetgen] parsed packet config:\n%v", string(packetConfigBytes))
 		len, err := packetgen.SendPacket(packetConfig, host, port)
 		if err != nil {
 			l.Error("error sending packet: %v", err)

packetgen/utils.go

@@ -34,6 +34,23 @@ func RandomMacAddr() net.HardwareAddr {
 	return net.HardwareAddr(addr.String())
 }
 
+// GetLocalIP returns the non loopback local IP of the host
+func LocalIP() string {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return ""
+	}
+	for _, address := range addrs {
+		// check the address type and if it is not a loopback the display it
+		if ipnet, ok := address.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
+			if ipnet.IP.To4() != nil {
+				return ipnet.IP.String()
+			}
+		}
+	}
+	return ""
+}
+
 // getIps returns a string slice to spoof ip packets with dummy source ip addresses
 func getIps() []string {
 	ips := make([]string, 0)

testconfig.json

@@ -63,12 +63,15 @@
             "dst_mac": "{{ random_mac_addr }}"
           },
           "ip": {
-            "src_ip": "{{ random_ip }}",
+            "src_ip": "{{ local_ip }}",
             "dst_ip": "{{ random_ip }}"
           },
           "tcp": {
             "src_port": "{{ random_port }}",
-            "dst_port": "{{ random_port }}"
+            "dst_port": "{{ random_port }}",
+            "flags": {
+              "syn": true
+            }
           },
           "udp": {
             "src_port": "{{ random_port }}",