tools/testing/selftests/net/reuseaddr_conflict.c

/*
 * Test for the regression introduced by
 *
 * b9470c27607b ("inet: kill smallest_size and smallest_port")
 *
 * If we open an ipv4 socket on a port with reuseaddr we shouldn't reset the tb
 * when we open the ipv6 conterpart, which is what was happening previously.
 */
#include <errno.h>
#include <error.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#define PORT 9999

int open_port(int ipv6, int any)
{
	int fd = -1;
	int reuseaddr = 1;
	int v6only = 1;
	int addrlen;
	int ret = -1;
	struct sockaddr *addr;
	int family = ipv6 ? AF_INET6 : AF_INET;

	struct sockaddr_in6 addr6 = {
		.sin6_family = AF_INET6,
		.sin6_port = htons(PORT),
		.sin6_addr = in6addr_any
	};
	struct sockaddr_in addr4 = {
		.sin_family = AF_INET,
		.sin_port = htons(PORT),
		.sin_addr.s_addr = any ? htonl(INADDR_ANY) : inet_addr("127.0.0.1"),
	};


	if (ipv6) {
		addr = (struct sockaddr*)&addr6;
		addrlen = sizeof(addr6);
	} else {
		addr = (struct sockaddr*)&addr4;
		addrlen = sizeof(addr4);
	}

	if ((fd = socket(family, SOCK_STREAM, IPPROTO_TCP)) < 0) {
		perror("socket");
		goto out;
	}

	if (ipv6 && setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&v6only,
			       sizeof(v6only)) < 0) {
		perror("setsockopt IPV6_V6ONLY");
		goto out;
	}

	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
		       sizeof(reuseaddr)) < 0) {
		perror("setsockopt SO_REUSEADDR");
		goto out;
	}

	if (bind(fd, addr, addrlen) < 0) {
		perror("bind");
		goto out;
	}

	if (any)
		return fd;

	if (listen(fd, 1) < 0) {
		perror("listen");
		goto out;
	}
	return fd;
out:
	close(fd);
	return ret;
}

int main(void)
{
	int listenfd;
	int fd1, fd2;

	fprintf(stderr, "Opening 127.0.0.1:%d\n", PORT);
	listenfd = open_port(0, 0);
	if (listenfd < 0)
		error(1, errno, "Couldn't open listen socket");
	fprintf(stderr, "Opening INADDR_ANY:%d\n", PORT);
	fd1 = open_port(0, 1);
	if (fd1 >= 0)
		error(1, 0, "Was allowed to create an ipv4 reuseport on a already bound non-reuseport socket");
	fprintf(stderr, "Opening in6addr_any:%d\n", PORT);
	fd1 = open_port(1, 1);
	if (fd1 < 0)
		error(1, errno, "Couldn't open ipv6 reuseport");
	fprintf(stderr, "Opening INADDR_ANY:%d\n", PORT);
	fd2 = open_port(0, 1);
	if (fd2 >= 0)
		error(1, 0, "Was allowed to create an ipv4 reuseport on a already bound non-reuseport socket");
	close(fd1);
	fprintf(stderr, "Opening INADDR_ANY:%d after closing ipv6 socket\n", PORT);
	fd1 = open_port(0, 1);
	if (fd1 >= 0)
		error(1, 0, "Was allowed to create an ipv4 reuseport on an already bound non-reuseport socket with no ipv6");
	fprintf(stderr, "Success");
	return 0;
}