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Merge pull request #8 from spurserh/master

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add port accessors and modifiers for TCP/UDP
This commit is contained in:
Song Gao 2016-05-10 11:11:24 -05:00
commit f87d2289c2
1 changed files with 31 additions and 0 deletions
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31
waterutil/tun_ipv4.go
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@ -28,11 +28,42 @@ func IPv4Source(packet []byte) net.IP {
return net.IPv4(packet[12], packet[13], packet[14], packet[15])
}
func SetIPv4Source(packet []byte, source net.IP) {
copy(packet[12:16], source.To4())
}
func IPv4Destination(packet []byte) net.IP {
return net.IPv4(packet[16], packet[17], packet[18], packet[19])
}
func SetIPv4Destination(packet []byte, dest net.IP) {
copy(packet[16:20], dest.To4())
}
func IPv4Payload(packet []byte) []byte {
ihl := packet[0] & 0x0F
return packet[ihl*4:]
}
// For TCP/UDP
func IPv4SourcePort(packet []byte) uint16 {
payload := IPv4Payload(packet)
return (uint16(payload[0]) << 8) | uint16(payload[1])
}
func IPv4DestinationPort(packet []byte) uint16 {
payload := IPv4Payload(packet)
return (uint16(payload[2]) << 8) | uint16(payload[3])
}
func SetIPv4SourcePort(packet []byte, port uint16) {
payload := IPv4Payload(packet)
payload[0] = byte(port >> 8)
payload[1] = byte(port & 0xFF)
}
func SetIPv4DestinationPort(packet []byte, port uint16) {
payload := IPv4Payload(packet)
payload[2] = byte(port >> 8)
payload[3] = byte(port & 0xFF)
}