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sniffer: fix accidental logging of good packets as bad

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We need to check vv.Size() instead of len(tcp), as tcp will always be 20 bytes
long.

PiperOrigin-RevId: 310218351
This commit is contained in:
Kevin Krakauer
2020-05-06 13:38:36 -07:00
committed by gVisor bot
parent 4631de620a
commit b08222cf3a
1 changed files with 4 additions and 4 deletions
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pkg/tcpip/link/sniffer/sniffer.go
+4 -4
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@@ -391,7 +391,7 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
break
}
udp := header.UDP(hdr)
if fragmentOffset == 0 && len(udp) >= header.UDPMinimumSize {
if fragmentOffset == 0 {
srcPort = udp.SourcePort()
dstPort = udp.DestinationPort()
details = fmt.Sprintf("xsum: 0x%x", udp.Checksum())
@@ -405,14 +405,14 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
break
}
tcp := header.TCP(hdr)
if fragmentOffset == 0 && len(tcp) >= header.TCPMinimumSize {
if fragmentOffset == 0 {
offset := int(tcp.DataOffset())
if offset < header.TCPMinimumSize {
details += fmt.Sprintf("invalid packet: tcp data offset too small %d", offset)
break
}
if offset > len(tcp) && !moreFragments {
details += fmt.Sprintf("invalid packet: tcp data offset %d larger than packet buffer length %d", offset, len(tcp))
if offset > vv.Size() && !moreFragments {
details += fmt.Sprintf("invalid packet: tcp data offset %d larger than packet buffer length %d", offset, vv.Size())
break
}