int server(unsigned short serv_port) {
int serv_sock = 0;
int clnt_sock = 0;
struct sockaddr_in serv_addr;
struct sockaddr_in clnt_addr;
unsigned int clnt_addr_len = 0;
/* create socket */
if ((serv_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
tcp_error("socket() failed");
/* construct serv_addr */
memset(&serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(serv_port);
/* bind */
if (bind(serv_sock, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
tcp_error("bind() failed");
/* listen */
if (listen(serv_sock, MAX_PENDING) < 0)
tcp_error("listen() failed");
while (1) {
clnt_addr_len = sizeof(clnt_addr);
/* accept */
if ((clnt_sock = accept(serv_sock,
(struct sockaddr *) &clnt_addr, &clnt_addr_len)) < 0)
tcp_error("accept() failed");
/* clnt_sock is connected to a client! */
printf("[from %s]\n", inet_ntoa(clnt_addr.sin_addr));
handle_client(clnt_sock);
}
/* NOT REACHED */
}
void handle_client(int clnt_sock) {
char rcvd_msg[RCV_BUF_SIZE];
int msg_size = 0;
/* receive */
if ((msg_size = recv(clnt_sock, rcvd_msg, RCV_BUF_SIZE, 0)) < 0)
tcp_error("recv() failed");
/* handle */
while (msg_size > 0) {
rcvd_msg[msg_size] = '\0';
printf("received: %s\n", (char *)&rcvd_msg);
if (ECHO_MODE)
echo(clnt_sock, rcvd_msg, msg_size);
if ((msg_size = recv(clnt_sock, rcvd_msg, RCV_BUF_SIZE, 0)) < 0)
tcp_error("recv() failed");
}
/* close */
close(clnt_sock);
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *ct,
struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info ctinfo,
const struct nf_hook_state *state)
{
struct net *net = nf_ct_net(ct);
struct nf_tcp_net *tn = nf_tcp_pernet(net);
struct nf_conntrack_tuple *tuple;
enum tcp_conntrack new_state, old_state;
unsigned int index, *timeouts;
enum ip_conntrack_dir dir;
const struct tcphdr *th;
struct tcphdr _tcph;
unsigned long timeout;
th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
if (th == NULL)
return -NF_ACCEPT;
if (tcp_error(th, skb, dataoff, state))
return -NF_ACCEPT;
if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
return -NF_ACCEPT;
spin_lock_bh(&ct->lock);
old_state = ct->proto.tcp.state;
dir = CTINFO2DIR(ctinfo);
index = get_conntrack_index(th);
new_state = tcp_conntracks[dir][index][old_state];
tuple = &ct->tuplehash[dir].tuple;
switch (new_state) {
case TCP_CONNTRACK_SYN_SENT:
if (old_state < TCP_CONNTRACK_TIME_WAIT)
break;
/* RFC 1122: "When a connection is closed actively,
* it MUST linger in TIME-WAIT state for a time 2xMSL
* (Maximum Segment Lifetime). However, it MAY accept
* a new SYN from the remote TCP to reopen the connection
* directly from TIME-WAIT state, if..."
* We ignore the conditions because we are in the
* TIME-WAIT state anyway.
*
* Handle aborted connections: we and the server
* think there is an existing connection but the client
* aborts it and starts a new one.
*/
if (((ct->proto.tcp.seen[dir].flags
| ct->proto.tcp.seen[!dir].flags)
& IP_CT_TCP_FLAG_CLOSE_INIT)
|| (ct->proto.tcp.last_dir == dir
&& ct->proto.tcp.last_index == TCP_RST_SET)) {
/* Attempt to reopen a closed/aborted connection.
* Delete this connection and look up again. */
spin_unlock_bh(&ct->lock);
/* Only repeat if we can actually remove the timer.
* Destruction may already be in progress in process
* context and we must give it a chance to terminate.
*/
if (nf_ct_kill(ct))
return -NF_REPEAT;
return NF_DROP;
}
/* Fall through */
case TCP_CONNTRACK_IGNORE:
/* Ignored packets:
*
* Our connection entry may be out of sync, so ignore
* packets which may signal the real connection between
* the client and the server.
*
* a) SYN in ORIGINAL
* b) SYN/ACK in REPLY
* c) ACK in reply direction after initial SYN in original.
*
* If the ignored packet is invalid, the receiver will send
* a RST we'll catch below.
*/
if (index == TCP_SYNACK_SET
&& ct->proto.tcp.last_index == TCP_SYN_SET
&& ct->proto.tcp.last_dir != dir
&& ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
/* b) This SYN/ACK acknowledges a SYN that we earlier
* ignored as invalid. This means that the client and
* the server are both in sync, while the firewall is
* not. We get in sync from the previously annotated
* values.
*/
old_state = TCP_CONNTRACK_SYN_SENT;
new_state = TCP_CONNTRACK_SYN_RECV;
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
ct->proto.tcp.last_end;
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
ct->proto.tcp.last_end;
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
ct->proto.tcp.last_win == 0 ?
1 : ct->proto.tcp.last_win;
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
ct->proto.tcp.last_wscale;
ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
ct->proto.tcp.last_flags;
memset(&ct->proto.tcp.seen[dir], 0,
sizeof(struct ip_ct_tcp_state));
break;
}
ct->proto.tcp.last_index = index;
ct->proto.tcp.last_dir = dir;
ct->proto.tcp.last_seq = ntohl(th->seq);
ct->proto.tcp.last_end =
segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
ct->proto.tcp.last_win = ntohs(th->window);
/* a) This is a SYN in ORIGINAL. The client and the server
* may be in sync but we are not. In that case, we annotate
* the TCP options and let the packet go through. If it is a
* valid SYN packet, the server will reply with a SYN/ACK, and
* then we'll get in sync. Otherwise, the server potentially
* responds with a challenge ACK if implementing RFC5961.
*/
if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
struct ip_ct_tcp_state seen = {};
ct->proto.tcp.last_flags =
ct->proto.tcp.last_wscale = 0;
tcp_options(skb, dataoff, th, &seen);
if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
ct->proto.tcp.last_flags |=
IP_CT_TCP_FLAG_WINDOW_SCALE;
ct->proto.tcp.last_wscale = seen.td_scale;
}
if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
ct->proto.tcp.last_flags |=
IP_CT_TCP_FLAG_SACK_PERM;
}
/* Mark the potential for RFC5961 challenge ACK,
* this pose a special problem for LAST_ACK state
* as ACK is intrepretated as ACKing last FIN.
*/
if (old_state == TCP_CONNTRACK_LAST_ACK)
ct->proto.tcp.last_flags |=
IP_CT_EXP_CHALLENGE_ACK;
}
spin_unlock_bh(&ct->lock);
nf_ct_l4proto_log_invalid(skb, ct, "invalid packet ignored in "
"state %s ", tcp_conntrack_names[old_state]);
return NF_ACCEPT;
case TCP_CONNTRACK_MAX:
/* Special case for SYN proxy: when the SYN to the server or
* the SYN/ACK from the server is lost, the client may transmit
* a keep-alive packet while in SYN_SENT state. This needs to
* be associated with the original conntrack entry in order to
* generate a new SYN with the correct sequence number.
*/
if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
spin_unlock_bh(&ct->lock);
return NF_ACCEPT;
}
/* Invalid packet */
pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
dir, get_conntrack_index(th), old_state);
spin_unlock_bh(&ct->lock);
nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
return -NF_ACCEPT;
case TCP_CONNTRACK_TIME_WAIT:
/* RFC5961 compliance cause stack to send "challenge-ACK"
* e.g. in response to spurious SYNs. Conntrack MUST
* not believe this ACK is acking last FIN.
*/
if (old_state == TCP_CONNTRACK_LAST_ACK &&
index == TCP_ACK_SET &&
ct->proto.tcp.last_dir != dir &&
ct->proto.tcp.last_index == TCP_SYN_SET &&
(ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
/* Detected RFC5961 challenge ACK */
ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
spin_unlock_bh(&ct->lock);
nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
return NF_ACCEPT; /* Don't change state */
}
break;
case TCP_CONNTRACK_SYN_SENT2:
/* tcp_conntracks table is not smart enough to handle
* simultaneous open.
*/
ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
break;
case TCP_CONNTRACK_SYN_RECV:
if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
new_state = TCP_CONNTRACK_ESTABLISHED;
break;
case TCP_CONNTRACK_CLOSE:
if (index == TCP_RST_SET
&& (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
&& before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
/* Invalid RST */
spin_unlock_bh(&ct->lock);
nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
return -NF_ACCEPT;
}
if (index == TCP_RST_SET
&& ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
&& ct->proto.tcp.last_index == TCP_SYN_SET)
|| (!test_bit(IPS_ASSURED_BIT, &ct->status)
&& ct->proto.tcp.last_index == TCP_ACK_SET))
&& ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
/* RST sent to invalid SYN or ACK we had let through
* at a) and c) above:
*
* a) SYN was in window then
* c) we hold a half-open connection.
*
* Delete our connection entry.
* We skip window checking, because packet might ACK
* segments we ignored. */
goto in_window;
}
/* Just fall through */
default:
/* Keep compilers happy. */
break;
}
if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
skb, dataoff, th)) {
spin_unlock_bh(&ct->lock);
return -NF_ACCEPT;
}
in_window:
/* From now on we have got in-window packets */
ct->proto.tcp.last_index = index;
ct->proto.tcp.last_dir = dir;
pr_debug("tcp_conntracks: ");
nf_ct_dump_tuple(tuple);
pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
(th->syn ? 1 : 0), (th->ack ? 1 : 0),
(th->fin ? 1 : 0), (th->rst ? 1 : 0),
old_state, new_state);
ct->proto.tcp.state = new_state;
if (old_state != new_state
&& new_state == TCP_CONNTRACK_FIN_WAIT)
ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
timeouts = nf_ct_timeout_lookup(ct);
if (!timeouts)
timeouts = tn->timeouts;
if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
timeout = timeouts[TCP_CONNTRACK_RETRANS];
else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
timeout = timeouts[TCP_CONNTRACK_UNACK];
else if (ct->proto.tcp.last_win == 0 &&
timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
timeout = timeouts[TCP_CONNTRACK_RETRANS];
else
timeout = timeouts[new_state];
spin_unlock_bh(&ct->lock);
if (new_state != old_state)
nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
/* If only reply is a RST, we can consider ourselves not to
have an established connection: this is a fairly common
problem case, so we can delete the conntrack
immediately. --RR */
if (th->rst) {
nf_ct_kill_acct(ct, ctinfo, skb);
return NF_ACCEPT;
}
/* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
* pickup with loose=1. Avoid large ESTABLISHED timeout.
*/
if (new_state == TCP_CONNTRACK_ESTABLISHED &&
timeout > timeouts[TCP_CONNTRACK_UNACK])
timeout = timeouts[TCP_CONNTRACK_UNACK];
} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
&& (old_state == TCP_CONNTRACK_SYN_RECV
|| old_state == TCP_CONNTRACK_ESTABLISHED)
&& new_state == TCP_CONNTRACK_ESTABLISHED) {
/* Set ASSURED if we see see valid ack in ESTABLISHED
after SYN_RECV or a valid answer for a picked up
connection. */
set_bit(IPS_ASSURED_BIT, &ct->status);
nf_conntrack_event_cache(IPCT_ASSURED, ct);
}
nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
return NF_ACCEPT;
}
void echo(int clnt_sock, char *rcvd_msg, int msg_size) {
if (send(clnt_sock, rcvd_msg, msg_size, 0) != msg_size)
tcp_error("send() failed");
}
/* Called when a new connection for this protocol found. */
static int tcp_new(struct ip_conntrack *conntrack,
struct sk_buff *skb, int hooknum)
{
struct iphdr *iph = skb->nh.iph;
size_t len = skb->len;
enum tcp_conntrack new_state;
struct tcphdr *tcph = (struct tcphdr *)((u_int32_t *)iph + iph->ihl);
#ifdef DEBUGP_VARS
struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0];
struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1];
#endif
/* Skip unclean packets */
if (tcp_error(skb, hooknum) != NF_ACCEPT)
return 0;
/* Don't need lock here: this conntrack not in circulation yet */
new_state
= tcp_conntracks[0][get_conntrack_index(tcph)]
[TCP_CONNTRACK_NONE];
/* Invalid: delete conntrack */
if (new_state >= TCP_CONNTRACK_MAX) {
DEBUGP("ip_ct_tcp: invalid new deleting.\n");
return 0;
}
if (new_state == TCP_CONNTRACK_SYN_SENT) {
/* SYN packet */
conntrack->proto.tcp.seen[0].td_end =
segment_seq_plus_len(ntohl(tcph->seq), len,
iph, tcph);
conntrack->proto.tcp.seen[0].td_maxwin = ntohs(tcph->window);
if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
conntrack->proto.tcp.seen[0].td_maxwin = 1;
conntrack->proto.tcp.seen[0].td_maxend =
conntrack->proto.tcp.seen[0].td_end;
tcp_options(tcph, &conntrack->proto.tcp.seen[0]);
conntrack->proto.tcp.seen[1].flags = 0;
conntrack->proto.tcp.seen[0].loose =
conntrack->proto.tcp.seen[1].loose = 0;
} else if (ip_ct_tcp_loose == 0) {
/* Don't try to pick up connections. */
return 0;
} else {
/*
* We are in the middle of a connection,
* its history is lost for us.
* Let's try to use the data from the packet.
*/
conntrack->proto.tcp.seen[0].td_end =
segment_seq_plus_len(ntohl(tcph->seq), len,
iph, tcph);
conntrack->proto.tcp.seen[0].td_maxwin = ntohs(tcph->window);
if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
conntrack->proto.tcp.seen[0].td_maxwin = 1;
conntrack->proto.tcp.seen[0].td_maxend =
conntrack->proto.tcp.seen[0].td_end +
conntrack->proto.tcp.seen[0].td_maxwin;
conntrack->proto.tcp.seen[0].td_scale = 0;
/* We assume SACK. Should we assume window scaling too? */
conntrack->proto.tcp.seen[0].flags =
conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM;
conntrack->proto.tcp.seen[0].loose =
conntrack->proto.tcp.seen[1].loose = ip_ct_tcp_loose;
}
conntrack->proto.tcp.seen[1].td_end = 0;
conntrack->proto.tcp.seen[1].td_maxend = 0;
conntrack->proto.tcp.seen[1].td_maxwin = 1;
conntrack->proto.tcp.seen[1].td_scale = 0;
/* tcp_packet will set them */
conntrack->proto.tcp.state = TCP_CONNTRACK_NONE;
conntrack->proto.tcp.last_index = TCP_NONE_SET;
DEBUGP("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
"receiver end=%u maxend=%u maxwin=%u scale=%i\n",
sender->td_end, sender->td_maxend, sender->td_maxwin,
sender->td_scale,
receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
receiver->td_scale);
return 1;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
enum ip_conntrack_info ctinfo,
struct sk_buff *skb, int hooknum)
{
struct iphdr *iph = skb->nh.iph;
size_t len = skb->len;
enum tcp_conntrack new_state, old_state;
enum ip_conntrack_dir dir;
struct tcphdr *tcph = (struct tcphdr *)((u_int32_t *)iph + iph->ihl);
unsigned long timeout;
unsigned int index;
/* Do not handle unclean packets, which could cause false alarms. */
if (tcp_error(skb, hooknum) != NF_ACCEPT)
return -NF_ACCEPT;
WRITE_LOCK(&tcp_lock);
old_state = conntrack->proto.tcp.state;
dir = CTINFO2DIR(ctinfo);
index = get_conntrack_index(tcph);
new_state = tcp_conntracks[dir][index][old_state];
switch (new_state) {
case TCP_CONNTRACK_IGNORE:
/* Either SYN in ORIGINAL
* or SYN/ACK in REPLY. */
if (index == TCP_SYNACK_SET
&& conntrack->proto.tcp.last_index == TCP_SYN_SET
&& conntrack->proto.tcp.last_dir != dir
&& ntohl(tcph->ack_seq) ==
conntrack->proto.tcp.last_end) {
/* This SYN/ACK acknowledges a SYN that we earlier
* ignored as invalid. This means that the client and
* the server are both in sync, while the firewall is
* not. We kill this session and block the SYN/ACK so
* that the client cannot but retransmit its SYN and
* thus initiate a clean new session.
*/
WRITE_UNLOCK(&tcp_lock);
if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
nf_log(PF_INET, (char *)iph, len,
"ip_ct_tcp: killing out of sync session ");
if (del_timer(&conntrack->timeout))
conntrack->timeout.function((unsigned long)
conntrack);
return -NF_DROP;
}
conntrack->proto.tcp.last_index = index;
conntrack->proto.tcp.last_dir = dir;
conntrack->proto.tcp.last_seq = ntohl(tcph->seq);
conntrack->proto.tcp.last_end =
segment_seq_plus_len(ntohl(tcph->seq), len, iph, tcph);
WRITE_UNLOCK(&tcp_lock);
if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
nf_log(PF_INET, (char *)iph, len,
"ip_ct_tcp: invalid packet ignored ");
return NF_ACCEPT;
case TCP_CONNTRACK_MAX:
/* Invalid packet */
DEBUGP("ip_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
dir, get_conntrack_index(tcph),
old_state);
WRITE_UNLOCK(&tcp_lock);
if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
nf_log(PF_INET, (char *)iph, len,
"ip_ct_tcp: invalid state ");
return -NF_ACCEPT;
case TCP_CONNTRACK_SYN_SENT:
if (old_state < TCP_CONNTRACK_TIME_WAIT)
break;
if ((conntrack->proto.tcp.seen[dir].flags &
IP_CT_TCP_FLAG_CLOSE_INIT)
|| after(ntohl(tcph->seq),
conntrack->proto.tcp.seen[dir].td_end)) {
/* Attempt to reopen a closed connection.
* Delete this connection and look up again. */
WRITE_UNLOCK(&tcp_lock);
if (del_timer(&conntrack->timeout))
conntrack->timeout.function((unsigned long)
conntrack);
return -NF_REPEAT;
} else {
WRITE_UNLOCK(&tcp_lock);
if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
nf_log(PF_INET, (char *)iph, len,
"ip_ct_tcp: invalid SYN ");
return -NF_ACCEPT;
}
case TCP_CONNTRACK_CLOSE:
if (index == TCP_RST_SET
&& test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
&& conntrack->proto.tcp.last_index == TCP_SYN_SET
&& ntohl(tcph->ack_seq) == conntrack->proto.tcp.last_end) {
/* RST sent to invalid SYN we had let trough
* SYN was in window then, tear down connection.
* We skip window checking, because packet might ACK
* segments we ignored in the SYN. */
goto in_window;
}
/* Just fall trough */
default:
/* Keep compilers happy. */
break;
}
if (!tcp_in_window(&conntrack->proto.tcp, dir, index,
iph, len, tcph)) {
WRITE_UNLOCK(&tcp_lock);
return -NF_ACCEPT;
}
in_window:
/* From now on we have got in-window packets */
conntrack->proto.tcp.last_index = index;
DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
"syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
NIPQUAD(iph->saddr), ntohs(tcph->source),
NIPQUAD(iph->daddr), ntohs(tcph->dest),
(tcph->syn ? 1 : 0), (tcph->ack ? 1 : 0),
(tcph->fin ? 1 : 0), (tcph->rst ? 1 : 0),
old_state, new_state);
conntrack->proto.tcp.state = new_state;
if (old_state != new_state
&& (new_state == TCP_CONNTRACK_FIN_WAIT
|| new_state == TCP_CONNTRACK_CLOSE))
conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
timeout = conntrack->proto.tcp.retrans >= ip_ct_tcp_max_retrans
&& *tcp_timeouts[new_state] > ip_ct_tcp_timeout_max_retrans
? ip_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
WRITE_UNLOCK(&tcp_lock);
if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
/* If only reply is a RST, we can consider ourselves not to
have an established connection: this is a fairly common
problem case, so we can delete the conntrack
immediately. --RR */
if (tcph->rst) {
if (del_timer(&conntrack->timeout))
conntrack->timeout.function((unsigned long)
conntrack);
return NF_ACCEPT;
}
} else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
&& (old_state == TCP_CONNTRACK_SYN_RECV
|| old_state == TCP_CONNTRACK_ESTABLISHED)
&& new_state == TCP_CONNTRACK_ESTABLISHED) {
/* Set ASSURED if we see see valid ack in ESTABLISHED
after SYN_RECV or a valid answer for a picked up
connection. */
set_bit(IPS_ASSURED_BIT, &conntrack->status);
}
ip_ct_refresh_acct(conntrack, ctinfo, iph, timeout);
return NF_ACCEPT;
}
