misc: small fix or general refactoring i did not bother commenting

modules/net_probe_upnp.go

@@ -1,6 +1,7 @@
 package modules
 
 import (
+	"fmt"
 	"net"
 
 	"github.com/bettercap/bettercap/log"
@@ -8,13 +9,18 @@ import (
 )
 
 func (p *Prober) sendProbeUPNP(from net.IP, from_hw net.HardwareAddr) {
-	err, raw := packets.NewUPNPProbe(from, from_hw)
+	name := fmt.Sprintf("%s:%d", packets.UPNPDestIP, packets.UPNPPort)
-	if err != nil {
+	if addr, err := net.ResolveUDPAddr("udp", name); err != nil {
-		log.Error("error while sending upnp probe: %v", err)
+		log.Debug("could not resolve %s.", name)
-		return
+	} else if con, err := net.DialUDP("udp", nil, addr); err != nil {
-	} else if err := p.Session.Queue.Send(raw); err != nil {
+		log.Debug("could not dial %s.", name)
-		log.Error("error sending upnp packet: %s", err)
 	} else {
-		log.Debug("sent %d bytes of UPNP probe", len(raw))
+		defer con.Close()
+		if wrote, _ := con.Write(packets.UPNPDiscoveryPayload); wrote > 0 {
+			p.Session.Queue.TrackSent(uint64(wrote))
+		} else {
+			p.Session.Queue.TrackError()
+		}
 	}
+
 }

packets/upnp.go

@@ -3,9 +3,6 @@ package packets
 import (
 	"fmt"
 	"net"
-
-	"github.com/google/gopacket"
-	"github.com/google/gopacket/layers"
 )
 
 const (
@@ -13,40 +10,12 @@ const (
 )
 
 var (
-	UPNPDestMac = net.HardwareAddr{0x01, 0x00, 0x5e, 0x00, 0x00, 0xfb}
+	UPNPDestMac          = net.HardwareAddr{0x01, 0x00, 0x5e, 0x00, 0x00, 0xfb}
-	UPNPDestIP  = net.ParseIP("239.255.255.250")
+	UPNPDestIP           = net.ParseIP("239.255.255.250")
-)
+	UPNPDiscoveryPayload = []byte("M-SEARCH * HTTP/1.1\r\n" +
-
-func NewUPNPProbe(from net.IP, from_hw net.HardwareAddr) (error, []byte) {
-	eth := layers.Ethernet{
-		SrcMAC:       from_hw,
-		DstMAC:       UPNPDestMac,
-		EthernetType: layers.EthernetTypeIPv4,
-	}
-
-	ip4 := layers.IPv4{
-		Protocol: layers.IPProtocolUDP,
-		Version:  4,
-		TTL:      64,
-		SrcIP:    from,
-		DstIP:    UPNPDestIP,
-	}
-
-	udp := layers.UDP{
-		SrcPort: layers.UDPPort(12345),
-		DstPort: layers.UDPPort(UPNPPort),
-	}
-
-	payload := []byte("M-SEARCH * HTTP/1.1\r\n" +
 		fmt.Sprintf("Host: %s:%d\r\n", UPNPDestIP, UPNPPort) +
 		"Man: ssdp:discover\r\n" +
 		"ST: ssdp:all\r\n" +
 		"MX: 2\r\n" +
 		"\r\n")
-
+)
-	if err := udp.SetNetworkLayerForChecksum(&ip4); err != nil {
-		return err, nil
-	}
-
-	return Serialize(&eth, &ip4, &udp, gopacket.Payload(payload))
-}