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net: tcp: Make sure that connection failure is propagated to app

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It is possible that TCP connect() will fail if for example network
interface does not have IP address set. In this case we close
the connection during net_tcp_connect() but do not set the return
code properly. This looks in the application like the connection
succeeded even if it was not.

As the tcp_in() call in net_tcp_connect() might close the connection,
we just take extra ref count while calling tcp_in(). Otherwise we
might access already freed connection.

Before the fix:

net_tcp_connect: context: 0x80757c0, local: 0.0.0.0, remote: 192.0.2.2
net_tcp_connect: conn: 0x8087320 src: 0.0.0.0, dst: 192.0.2.2
tcp_in: [LISTEN Seq=1604170158 Ack=0]
tcp_conn_close_debug: conn: 0x8087320 closed by TCP stack (tcp_in():3626)
tcp_conn_close_debug: LISTEN->CLOSED
tcp_conn_unref: conn: 0x8087320, ref_count=1
net_tcp_connect: conn: 0x8087320, ret=0

After the fix:

net_tcp_connect: context: 0x80757c0, local: 0.0.0.0, remote: 192.0.2.2
net_tcp_connect: conn: 0x8087320 src: 0.0.0.0, dst: 192.0.2.2
tcp_conn_ref: conn: 0x8087320, ref_count: 2
tcp_in: [LISTEN Seq=1604170158 Ack=0]
tcp_conn_close_debug: conn: 0x8087320 closed by TCP stack (tcp_in():3626)
tcp_conn_close_debug: LISTEN->CLOSED
tcp_conn_unref: conn: 0x8087320, ref_count=2
net_tcp: tcp_conn_unref: conn: 0x8087320, ref_count=1
net_tcp: net_tcp_connect: conn: 0x8087320, ret=-128

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>
This commit is contained in:
Jukka Rissanen 2024-09-24 11:15:46 +03:00 committed by Fabio Baltieri
parent 57a8a7c350
commit a41f625fab
1 changed files with 14 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
subsys/net/ip/tcp.c
View File

@ -3948,16 +3948,21 @@ int net_tcp_connect(struct net_context *context,
* a TCP connection to be established
*/
conn->in_connect = !IS_ENABLED(CONFIG_NET_TEST_PROTOCOL);
/* The ref will make sure that if the connection is closed in tcp_in(),
* we do not access already freed connection.
*/
tcp_conn_ref(conn);
(void)tcp_in(conn, NULL);
if (!IS_ENABLED(CONFIG_NET_TEST_PROTOCOL)) {
if (conn->state == TCP_UNUSED || conn->state == TCP_CLOSED) {
ret = -errno;
goto out;
ret = -ENOTCONN;
goto out_unref;
} else if ((K_TIMEOUT_EQ(timeout, K_NO_WAIT)) &&
conn->state != TCP_ESTABLISHED) {
ret = -EINPROGRESS;
goto out;
goto out_unref;
} else if (k_sem_take(&conn->connect_sem, timeout) != 0 &&
conn->state != TCP_ESTABLISHED) {
if (conn->in_connect) {
@ -3966,11 +3971,15 @@ int net_tcp_connect(struct net_context *context,
}
ret = -ETIMEDOUT;
goto out;
goto out_unref;
}
conn->in_connect = false;
}
out:
out_unref:
tcp_conn_unref(conn);
out:
NET_DBG("conn: %p, ret=%d", conn, ret);
return ret;