[2/2] socket: Add new test for connect

  This commit adds a new test for the connect function.
---
 socket/Makefile      |   1 +
 socket/tst-connect.c | 109 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 socket/tst-connect.c
  

> This commit adds a new test for the connect function.

Overall, this looks fine to me. I have a couple of suggestions.

> diff --git a/socket/Makefile b/socket/Makefile
> index 74ca5b8452..fc1bd0a260 100644
> --- a/socket/Makefile
> +++ b/socket/Makefile
> @@ -70,6 +70,7 @@ tests := \
>    tst-accept4 \
>    tst-cmsg_cloexec \
>    tst-cmsghdr \
> +  tst-connect \
>    tst-sockopt \
>    # tests

OK. New test.

> diff --git a/socket/tst-connect.c b/socket/tst-connect.c
> new file mode 100644
> index 0000000000..44999d2953
> --- /dev/null
> +++ b/socket/tst-connect.c
> @@ -0,0 +1,109 @@
> +/* Test the connect function.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <arpa/inet.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <signal.h>
> +#include <stdbool.h>
> +#include <support/check.h>
> +#include <support/xsocket.h>
> +#include <support/xunistd.h>
> +#include <sys/socket.h>
> +#include <stdio.h>
> +
> +static struct sockaddr_in server_address;
> +
> +int
> +open_socket (int domain, int type, int protocol)
> +{
> +  int fd = socket (domain, type, protocol);
> +  if (fd < 0)
> +  {
> +    if (errno == EAFNOSUPPORT)
> +      FAIL_UNSUPPORTED ("The host does not support IPv4");

Considering we are assuming inside open_socket that we will be using
IPv4, and since both calls to open_socket are with the same args,
perhaps let's get rid of args for open_socket?

> +    else
> +      FAIL_EXIT1 ("socket (%d, %d, %d): %m\n", domain, type, protocol);
> +  }
> +  return fd;
> +}
> +
> +static pid_t
> +start_server (void)
> +{
> +
> +  server_address.sin_family = AF_INET;
> +  server_address.sin_port = 0;
> +  server_address.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
> +
> +  int server_sock = open_socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
> +
> +  xbind (server_sock, (struct sockaddr *) &server_address,
> +    sizeof (server_address));
> +
> +  socklen_t sa_len = sizeof (server_address);
> +  xgetsockname (server_sock, (struct sockaddr *) &server_address, &sa_len);
> +  printf ("Server listen on port %d\n",ntohs (server_address.sin_port));
> +  xlisten (server_sock, 5);

The printf doesn't seem necessary.
OK otherwise.

> +
> +  pid_t my_pid = xfork ();
> +  if (my_pid > 0)
> +  {
> +    xclose (server_sock);
> +    return my_pid;

OK. Parent returns PID of child.

> +  }
> +
> +  struct sockaddr_in client_address;
> +  socklen_t ca_len = sizeof (server_address);
> +  int client_sock = xaccept (server_sock,
> +    (struct sockaddr *) &client_address, &ca_len);
> +  printf ("socket accepted %d\n",client_sock);
> +
> +  _exit (0);
> +}

OK. Child waits for a connection, then exits.
This printf can be skipped too.

> +
> +static int
> +do_test (void)
> +{
> +  pid_t serv_pid;
> +  struct sockaddr_in peer;
> +  socklen_t peer_len;
> +
> +  serv_pid = start_server ();
> +  int client_sock = open_socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
> +  xconnect (client_sock, (const struct sockaddr *) &server_address,
> +    sizeof (server_address));

OK.

> +  int result = connect (client_sock, (const struct sockaddr *) &server_address,
> +    sizeof (server_address));
> +  if (result == 0  || errno != EISCONN)
> +    FAIL_EXIT1 ("Second connect (%d), should fail with EISCONN: %m",
> +      client_sock);

OK. Testing that a second connect fails.
Took me a long moment to realize why there's a second connect call
right after an xconnect. Maybe worth a comment :)

> +
> +  peer_len = sizeof (peer);
> +  xgetpeername (client_sock, (struct sockaddr *) &peer, &peer_len);
> +  TEST_COMPARE (peer_len, sizeof (peer));
> +  TEST_COMPARE (peer.sin_port, server_address.sin_port);
> +  TEST_COMPARE_BLOB (&peer.sin_addr, sizeof (peer.sin_addr),
> +    &server_address.sin_addr, sizeof (server_address.sin_addr));

OK. Checking that the peer we just connected to matches the server.

> +
> +  int status;
> +  xwaitpid (serv_pid, &status, 0);
> +  TEST_COMPARE (status, 0);
> +  return 0;
> +}
> +#include <support/test-driver.c>

OK.

--
Arjun Shankar
he/him/his