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Do not modify IGMP packets when verifying checksum 

PiperOrigin-RevId: 353336894
This commit is contained in:
Ghanan Gowripalan 2021-01-22 16:03:27 -08:00 committed by gVisor bot
parent f190e13a74
commit 76da673a0d
1 changed files with 7 additions and 8 deletions
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15
pkg/tcpip/network/ipv4/igmp.go
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@ -157,14 +157,13 @@ func (igmp *igmpState) handleIGMP(pkt *stack.PacketBuffer) {
}
h := header.IGMP(headerView)
// Temporarily reset the checksum field to 0 in order to calculate the proper
// checksum.
wantChecksum := h.Checksum()
h.SetChecksum(0)
gotChecksum := ^header.ChecksumVV(pkt.Data, 0 /* initial */)
h.SetChecksum(wantChecksum)
if gotChecksum != wantChecksum {
// As per RFC 1071 section 1.3,
//
// To check a checksum, the 1's complement sum is computed over the
// same set of octets, including the checksum field. If the result
// is all 1 bits (-0 in 1's complement arithmetic), the check
// succeeds.
if header.ChecksumVV(pkt.Data, 0 /* initial */) != 0xFFFF {
received.checksumErrors.Increment()
return
}