new: implemented syn.scan module (closes #67)

packets/tcp.go

@@ -0,0 +1,29 @@
+package packets
+
+import (
+	"github.com/google/gopacket/layers"
+	"net"
+)
+
+func NewTCPSyn(from net.IP, from_hw net.HardwareAddr, to net.IP, to_hw net.HardwareAddr, srcPort int, dstPort int) (error, []byte) {
+	eth := layers.Ethernet{
+		SrcMAC:       from_hw,
+		DstMAC:       to_hw,
+		EthernetType: layers.EthernetTypeIPv4,
+	}
+	ip4 := layers.IPv4{
+		Protocol: layers.IPProtocolTCP,
+		Version:  4,
+		TTL:      64,
+		SrcIP:    from,
+		DstIP:    to,
+	}
+	tcp := layers.TCP{
+		SrcPort: layers.TCPPort(srcPort),
+		DstPort: layers.TCPPort(dstPort),
+		SYN:     true,
+	}
+	tcp.SetNetworkLayerForChecksum(&ip4)
+
+	return Serialize(&eth, &ip4, &tcp)
+}