Mirrors_Framework/nuttx
1
0
Fork 0
mirror of https://github.com/apache/nuttx.git synced 2026-05-21 21:34:07 +08:00
Code Issues Actions 1 Packages Projects Releases Wiki Activity

net/tcp: support OTW SEQ number check except SYN-SEND state

Browse Source 
According rfc793 p69, from state SYN-RECEIVED to state TIME-WAIT, if the incoming segment is not acceptable, an acknowledgment should be sent in reply (unless the RST bit is set):
<SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>

Signed-off-by: wenquan1 <wenquan1@xiaomi.com>
This commit is contained in:
wenquan1
2025-08-20 11:25:12 +08:00
committed by archer
parent 758b6dd847
commit c4494c714c
1 changed files with 42 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/tcp/tcp_input.c
+42 -3
View File
@@ -744,10 +744,49 @@ static void tcp_input(FAR struct net_driver_s *dev, uint8_t domain,
conn = tcp_active(dev, tcp);
if (conn)
{
/* We found an active connection.. Check for the subsequent SYN
/* RFC793, 1) page 37 Reset Processing: "In all states except
* SYN-SENT, all reset (RST) segments are validated by checking
* their SEQ-fields."
* 2) page 69 In all states except SYN-SENT: "If an incoming
* segment is not acceptable, an acknowledgment should be sent
* in reply (unless the RST bit is set, if so drop the segment
* and return)".
*/
if ((conn->tcpstateflags & TCP_STATE_MASK) != TCP_SYN_SENT &&
((conn->tcpstateflags & TCP_STATE_MASK) >= TCP_SYN_RCVD &&
(conn->tcpstateflags & TCP_STATE_MASK) <= TCP_LAST_ACK))
{
uint32_t seq;
uint32_t rcvseq;
uint32_t endseq;
seq = tcp_getsequence(tcp->seqno);
rcvseq = tcp_getsequence(conn->rcvseq);
endseq = seq + dev->d_len - iplen - ((tcp->tcpoffset >> 4) << 2);
if ((tcp->flags & (TCP_SYN | TCP_FIN)) != 0)
{
endseq += 1;
}
if (TCP_SEQ_LT(endseq, rcvseq) || TCP_SEQ_GT(seq, conn->rcv_adv))
{
if ((tcp->flags & TCP_RST) == 0)
{
tcp_send(dev, conn, TCP_ACK, tcpiplen);
return;
}
else
{
goto drop;
}
}
}
/* RFC793,p71 In all states except SYN-SENT: "If the SYN is in the
* window it is an error, send a reset", except the subsequent SYN
* arriving in TCP_SYN_RCVD state after the SYNACK packet was
* lost. To avoid other issues, reset any active connection
* where a SYN arrives in a state != TCP_SYN_RCVD.
* lost.
*/
if ((conn->tcpstateflags & TCP_STATE_MASK) != TCP_SYN_RCVD &&