diff options
Diffstat (limited to 'pkg/tcpip/transport')
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 00c0c9a92..f14f0ca65 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -299,6 +299,15 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error { return nil } + // RFC 793, Section 3.9, page 69, states that in the SYN-RCVD state, a + // sequence number outside of the window causes an ACK with the proper seq + // number and "After sending the acknowledgment, drop the unacceptable + // segment and return." + if !s.sequenceNumber.InWindow(h.ackNum, h.rcvWnd) { + h.ep.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck, h.iss+1, h.ackNum, h.rcvWnd) + return nil + } + if s.flagIsSet(header.TCPFlagSyn) && s.sequenceNumber != h.ackNum-1 { // We received two SYN segments with different sequence // numbers, so we reset this and restart the whole |