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net/tcp: discard fin packet in LISTEN state

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Discard fin packet in LISTEN state

Signed-off-by: wenquan1 <wenquan1@xiaomi.com>
This commit is contained in:
wenquan1
2025-08-15 15:19:13 +08:00
committed by Xiang Xiao
parent 302731ad1a
commit cc0cc552fc
1 changed files with 83 additions and 75 deletions
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net/tcp/tcp_input.c
+83 -75
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@@ -768,105 +768,113 @@ static void tcp_input(FAR struct net_driver_s *dev, uint8_t domain,
* it is an old packet and we send a RST.
*/
if ((tcp->flags & TCP_CTL) == TCP_SYN)
{
/* This is a SYN packet for a connection. Find the connection
* listening on this port.
*/
tmp16 = tcp->destport;
tmp16 = tcp->destport;
#ifdef CONFIG_NET_IPv6
# ifdef CONFIG_NET_IPv4
if (domain == PF_INET6)
if (domain == PF_INET6)
# endif
{
net_ipv6addr_copy(&uaddr.ipv6.laddr, IPv6BUF->destipaddr);
}
{
net_ipv6addr_copy(&uaddr.ipv6.laddr, IPv6BUF->destipaddr);
}
#endif
#ifdef CONFIG_NET_IPv4
# ifdef CONFIG_NET_IPv6
if (domain == PF_INET)
if (domain == PF_INET)
# endif
{
net_ipv4addr_copy(uaddr.ipv4.laddr,
net_ip4addr_conv32(IPv4BUF->destipaddr));
}
{
net_ipv4addr_copy(uaddr.ipv4.laddr,
net_ip4addr_conv32(IPv4BUF->destipaddr));
}
#endif
#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
if ((conn = tcp_findlistener(&uaddr, tmp16, domain)) != NULL)
if ((conn = tcp_findlistener(&uaddr, tmp16, domain)) != NULL)
#else
if ((conn = tcp_findlistener(&uaddr, tmp16)) != NULL)
if ((conn = tcp_findlistener(&uaddr, tmp16)) != NULL)
#endif
{
/* According rfc793 p65&66, In LISTEN state, first ignore packet
* contains RST flag, second reset packet contains ACK flag,
* finally if the packet is not a SYN, ignore it.
*/
if ((tcp->flags & TCP_CTL) != TCP_SYN)
{
if (!tcp_backlogavailable(conn))
if ((tcp->flags & TCP_ACK) != 0)
{
nerr("ERROR: no free containers for TCP BACKLOG!\n");
goto drop;
goto reset;
}
/* We matched the incoming packet with a connection in LISTEN.
* We now need to create a new connection and send a SYNACK in
* response.
goto drop;
}
if (!tcp_backlogavailable(conn))
{
nerr("ERROR: no free containers for TCP BACKLOG!\n");
goto drop;
}
/* We matched the incoming packet with a connection in LISTEN.
* We now need to create a new connection and send a SYNACK in
* response.
*/
/* First allocate a new connection structure and see if there is
* any user application to accept it.
*/
conn = tcp_alloc_accept(dev, tcp, conn);
if (conn)
{
/* The connection structure was successfully allocated and has
* been initialized in the TCP_SYN_RECVD state. The expected
* sequence of events is then the rest of the 3-way handshake:
*
* 1. We just received a TCP SYN packet from a remote host.
* 2. We will send the SYN-ACK response below (perhaps
* repeatedly in the event of a timeout)
* 3. Then we expect to receive an ACK from the remote host
* indicated the TCP socket connection is ESTABLISHED.
*
* Possible failure:
*
* 1. The ACK is never received. This will be handled by
* a timeout managed by tcp_timer().
* 2. The listener "unlistens()". This will be handled by
* the failure of tcp_accept_connection() when the ACK is
* received.
*/
/* First allocate a new connection structure and see if there is
* any user application to accept it.
conn->crefs = 1;
}
if (!conn)
{
/* Either (1) all available connections are in use, or (2)
* there is no application in place to accept the connection.
* We drop packet and hope that the remote end will retransmit
* the packet at a time when we have more spare connections
* or someone waiting to accept the connection.
*/
conn = tcp_alloc_accept(dev, tcp, conn);
if (conn)
{
/* The connection structure was successfully allocated and has
* been initialized in the TCP_SYN_RECVD state. The expected
* sequence of events is then the rest of the 3-way handshake:
*
* 1. We just received a TCP SYN packet from a remote host.
* 2. We will send the SYN-ACK response below (perhaps
* repeatedly in the event of a timeout)
* 3. Then we expect to receive an ACK from the remote host
* indicated the TCP socket connection is ESTABLISHED.
*
* Possible failure:
*
* 1. The ACK is never received. This will be handled by
* a timeout managed by tcp_timer().
* 2. The listener "unlistens()". This will be handled by
* the failure of tcp_accept_connection() when the ACK is
* received.
*/
conn->crefs = 1;
}
if (!conn)
{
/* Either (1) all available connections are in use, or (2)
* there is no application in place to accept the connection.
* We drop packet and hope that the remote end will retransmit
* the packet at a time when we have more spare connections
* or someone waiting to accept the connection.
*/
#ifdef CONFIG_NET_STATISTICS
g_netstats.tcp.syndrop++;
g_netstats.tcp.syndrop++;
#endif
nerr("ERROR: No free TCP connections\n");
goto drop;
}
net_incr32(conn->rcvseq, 1); /* ack SYN */
/* Parse the TCP MSS option, if present. */
tcp_parse_option(dev, conn, iplen);
/* Our response will be a SYNACK. */
tcp_synack(dev, conn, TCP_ACK | TCP_SYN);
return;
nerr("ERROR: No free TCP connections\n");
goto drop;
}
net_incr32(conn->rcvseq, 1); /* ack SYN */
/* Parse the TCP MSS option, if present. */
tcp_parse_option(dev, conn, iplen);
/* Our response will be a SYNACK. */
tcp_synack(dev, conn, TCP_ACK | TCP_SYN);
return;
}
nwarn("WARNING: SYN with no listener (or old packet) .. reset\n");