common

func CalculateIPv4Checksum ¶

func CalculateIPv4Checksum(bytes []byte) uint16

CalculateIPv4Checksum calculates the IPv4 checksum for the given bytes. copied from gopacket/layers/ip4.go because they didn't export one. for whatever some reason..

func UpdateIPv4Checksum ¶

func UpdateIPv4Checksum(ip *layers.IPv4)

UpdateIPv4Checksum updates the IPv4 checksum field and the raw bytes for a gopacket IPv4 layer.

func UpdateTCPChecksum ¶

func UpdateTCPChecksum(tcp *layers.TCP, ip *layers.IPv4)

UpdateTCPChecksum updates the TCP checksum field and the raw bytes for a gopacket TCP layer.

The TCP checksum covers a pseudo-header derived from the IPv4 source and destination addresses, so ip must be the TCP layer's network layer. A freshly decoded packet does not carry that association, which is why the caller passes it explicitly; without it ComputeChecksum fails and the checksum would be left zero. ip may be nil only when the TCP layer already has its network layer set.