initial commit

waterutil/tun_ipv4.go

@@ -0,0 +1,38 @@
+package waterutil
+
+import (
+	"net"
+)
+
+func IPv4DSCP(packet []byte) byte {
+	return packet[1] >> 2
+}
+
+func IPv4ECN(packet []byte) byte {
+	return packet[1] & 0x03
+}
+
+func IPv4Identification(packet []byte) [2]byte {
+	return [2]byte{packet[4], packet[5]}
+}
+
+func IPv4TTL(packet []byte) byte {
+	return packet[8]
+}
+
+func IPv4Protocol(packet []byte) IPProtocol {
+	return IPProtocol(packet[9])
+}
+
+func IPv4Source(packet []byte) net.IP {
+	return net.IPv4(packet[12], packet[13], packet[14], packet[15])
+}
+
+func IPv4Destination(packet []byte) net.IP {
+	return net.IPv4(packet[16], packet[17], packet[18], packet[19])
+}
+
+func IPv4Payload(packet []byte) []byte {
+	ihl := packet[0] & 0x0F
+	return packet[ihl*4:]
+}