diff options
| author | Ghanan Gowripalan <ghanan@google.com> | 2021-06-24 22:38:14 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2021-06-24 22:45:17 -0700 |
| commit | 1f113b96e68fed452e40855db0cf3efa24b2b9b6 (patch) | |
| tree | 7af96816bd25d99469b90b77d9c69204b3559a33 /pkg/tcpip/header/ipv4.go | |
| parent | 49986674aaefd1aff50cc35cf1089206e174325c (diff) | |
Incrementally update checksum when NAT-ing
...instead of calculating a fresh checksum to avoid re-calcalculating
a checksum on unchanged bytes.
Fixes #5340.
PiperOrigin-RevId: 381403888
Diffstat (limited to 'pkg/tcpip/header/ipv4.go')
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index e9abbb709..dcc549c7b 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -305,6 +305,18 @@ func (b IPv4) DestinationAddress() tcpip.Address { return tcpip.Address(b[dstAddr : dstAddr+IPv4AddressSize]) } +// SetSourceAddressWithChecksumUpdate implements ChecksummableNetwork. +func (b IPv4) SetSourceAddressWithChecksumUpdate(new tcpip.Address) { + b.SetChecksum(^checksumUpdate2ByteAlignedAddress(^b.Checksum(), b.SourceAddress(), new)) + b.SetSourceAddress(new) +} + +// SetDestinationAddressWithChecksumUpdate implements ChecksummableNetwork. +func (b IPv4) SetDestinationAddressWithChecksumUpdate(new tcpip.Address) { + b.SetChecksum(^checksumUpdate2ByteAlignedAddress(^b.Checksum(), b.DestinationAddress(), new)) + b.SetDestinationAddress(new) +} + // padIPv4OptionsLength returns the total length for IPv4 options of length l // after applying padding according to RFC 791: // The internet header padding is used to ensure that the internet |