Re: [PATCH net-next v2] selftests: net: Add support for testing SO_RCVMARK and SO_RCVPRIORITY

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Anna Emese Nyiri wrote:
> Introduce tests to verify the correct functionality of the SO_RCVMARK and 
> SO_RCVPRIORITY socket options.
> 
> Key changes include:
> 
> - so_rcv_listener.c: Implements a receiver application to test the correct 
> behavior of the SO_RCVMARK and SO_RCVPRIORITY options.
> - test_so_rcv.sh: Provides a shell script to automate testing for these options.
> - Makefile: Integrates test_so_rcv.sh into the kernel selftests.
> 
> v2:
> 
> - Add the C part to TEST_GEN_PROGS and .gitignore.
> - Modify buffer space and add IPv6 testing option
> in so_rcv_listener.c.
> - Add IPv6 testing, remove unnecessary comment,
> add kselftest exit codes, run both binaries in a namespace,
> and add sleep in test_so_rcv.sh.
> The sleep was added to ensure that the listener process has
> enough time to start before the sender attempts to connect.
> - Rebased on net-next.
> 
> v1:
> 
> https://lore.kernel.org/netdev/20250129143601.16035-2-annaemesenyiri@gmail.com/
> 
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Suggested-by: Ferenc Fejes <fejes@inf.elte.hu>
> Signed-off-by: Anna Emese Nyiri <annaemesenyiri@gmail.com>
> ---
>  tools/testing/selftests/net/.gitignore        |   1 +
>  tools/testing/selftests/net/Makefile          |   2 +
>  tools/testing/selftests/net/so_rcv_listener.c | 165 ++++++++++++++++++
>  tools/testing/selftests/net/test_so_rcv.sh    |  73 ++++++++
>  4 files changed, 241 insertions(+)
>  create mode 100644 tools/testing/selftests/net/so_rcv_listener.c
>  create mode 100755 tools/testing/selftests/net/test_so_rcv.sh
> 
> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
> index 28a715a8ef2b..80dcae53ef55 100644
> --- a/tools/testing/selftests/net/.gitignore
> +++ b/tools/testing/selftests/net/.gitignore
> @@ -42,6 +42,7 @@ socket
>  so_incoming_cpu
>  so_netns_cookie
>  so_txtime
> +so_rcv_listener
>  stress_reuseport_listen
>  tap
>  tcp_fastopen_backup_key
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index 73ee88d6b043..fe3491dea7c5 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -33,6 +33,7 @@ TEST_PROGS += gro.sh
>  TEST_PROGS += gre_gso.sh
>  TEST_PROGS += cmsg_so_mark.sh
>  TEST_PROGS += cmsg_so_priority.sh
> +TEST_PROGS += test_so_rcv.sh
>  TEST_PROGS += cmsg_time.sh cmsg_ipv6.sh
>  TEST_PROGS += netns-name.sh
>  TEST_PROGS += nl_netdev.py
> @@ -89,6 +90,7 @@ TEST_GEN_FILES += sctp_hello
>  TEST_GEN_FILES += ip_local_port_range
>  TEST_GEN_PROGS += bind_wildcard
>  TEST_GEN_PROGS += bind_timewait
> +TEST_GEN_PROGS += so_rcv_listener
>  TEST_PROGS += test_vxlan_mdb.sh
>  TEST_PROGS += test_bridge_neigh_suppress.sh
>  TEST_PROGS += test_vxlan_nolocalbypass.sh
> diff --git a/tools/testing/selftests/net/so_rcv_listener.c b/tools/testing/selftests/net/so_rcv_listener.c
> new file mode 100644
> index 000000000000..693fc1e3d44d
> --- /dev/null
> +++ b/tools/testing/selftests/net/so_rcv_listener.c
> @@ -0,0 +1,165 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <errno.h>
> +#include <netdb.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <linux/types.h>
> +#include <sys/socket.h>
> +#include <netinet/in.h>
> +#include <arpa/inet.h>
> +
> +#ifndef SO_RCVPRIORITY
> +#define SO_RCVPRIORITY 82
> +#endif
> +
> +struct options {
> +	__u32 val;
> +	int name;
> +	int rcvname;
> +	const char *host;
> +	const char *service;
> +} opt;
> +
> +static void __attribute__((noreturn)) usage(const char *bin)
> +{
> +	printf("Usage: %s [opts] <dst host> <dst port / service>\n", bin);
> +	printf("Options:\n"
> +		"\t\t-M val  Test SO_RCVMARK\n"
> +		"\t\t-P val  Test SO_RCVPRIORITY\n"
> +		"");
> +	exit(EXIT_FAILURE);
> +}
> +
> +static void parse_args(int argc, char *argv[])
> +{
> +	int o;
> +
> +	while ((o = getopt(argc, argv, "M:P:")) != -1) {
> +		switch (o) {
> +		case 'M':
> +			opt.val = atoi(optarg);
> +			opt.name = SO_MARK;
> +			opt.rcvname = SO_RCVMARK;
> +			break;
> +		case 'P':
> +			opt.val = atoi(optarg);
> +			opt.name = SO_PRIORITY;
> +			opt.rcvname = SO_RCVPRIORITY;
> +			break;
> +		default:
> +			usage(argv[0]);
> +			break;
> +		}
> +	}
> +
> +	if (optind != argc - 2)
> +		usage(argv[0]);
> +
> +	opt.host = argv[optind];
> +	opt.service = argv[optind + 1];
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int err = 0;
> +	int recv_fd = -1;
> +	int ret_value = 0;
> +	__u32 recv_val;
> +	struct cmsghdr *cmsg;
> +	char cbuf[CMSG_SPACE(sizeof(__u32))];
> +	char recv_buf[CMSG_SPACE(sizeof(__u32))];
> +	struct iovec iov[1];
> +	struct msghdr msg;
> +	struct sockaddr_in recv_addr4;
> +	struct sockaddr_in6 recv_addr6;
> +
> +	parse_args(argc, argv);
> +
> +	int family = strchr(opt.host, ':') ? AF_INET6 : AF_INET;
> +
> +	recv_fd = socket(family, SOCK_DGRAM, IPPROTO_UDP);
> +	if (recv_fd < 0) {
> +		perror("Can't open recv socket");
> +		ret_value = -errno;
> +		goto cleanup;
> +	}
> +
> +	err = setsockopt(recv_fd, SOL_SOCKET, opt.rcvname, &opt.val, sizeof(opt.val));
> +	if (err < 0) {
> +		perror("Recv setsockopt error");
> +		ret_value = -errno;
> +		goto cleanup;
> +	}
> +
> +	if (family == AF_INET) {
> +		memset(&recv_addr4, 0, sizeof(recv_addr4));
> +		recv_addr4.sin_family = family;
> +		recv_addr4.sin_port = htons(atoi(opt.service));
> +
> +		if (inet_pton(family, opt.host, &recv_addr4.sin_addr) <= 0) {
> +			perror("Invalid IPV4 address");
> +			ret_value = -errno;
> +			goto cleanup;
> +		}
> +
> +		err = bind(recv_fd, (struct sockaddr *)&recv_addr4, sizeof(recv_addr4));
> +	} else {
> +		memset(&recv_addr6, 0, sizeof(recv_addr6));
> +		recv_addr6.sin6_family = family;
> +		recv_addr6.sin6_port = htons(atoi(opt.service));
> +
> +		if (inet_pton(family, opt.host, &recv_addr6.sin6_addr) <= 0) {
> +			perror("Invalid IPV6 address");
> +			ret_value = -errno;
> +			goto cleanup;
> +		}
> +
> +		err = bind(recv_fd, (struct sockaddr *)&recv_addr6, sizeof(recv_addr6));
> +	}
> +
> +	if (err < 0) {
> +		perror("Recv bind error");
> +		ret_value = -errno;
> +		goto cleanup;
> +	}
> +
> +	iov[0].iov_base = recv_buf;
> +	iov[0].iov_len = sizeof(recv_buf);
> +
> +	memset(&msg, 0, sizeof(msg));
> +	msg.msg_iov = iov;
> +	msg.msg_iovlen = 1;
> +	msg.msg_control = cbuf;
> +	msg.msg_controllen = sizeof(cbuf);
> +
> +	err = recvmsg(recv_fd, &msg, 0);
> +	if (err < 0) {
> +		perror("Message receive error");
> +		ret_value = -errno;
> +		goto cleanup;
> +	}
> +
> +	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
> +		if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == opt.name) {
> +			recv_val = *(__u32 *)CMSG_DATA(cmsg);
> +			printf("Received value: %u\n", recv_val);
> +
> +			if (recv_val != opt.val) {
> +				fprintf(stderr, "Error: expected value: %u, got: %u\n",
> +					opt.val, recv_val);
> +				ret_value = -EINVAL;

This test will return success if no cmsg of cmsg_type opt.name is
encountered. You probably want to fail in that case.

> +				goto cleanup;
> +			}
> +		}
> +	}
> +