reuseport_addr_any.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3/* Test that sockets listening on a specific address are preferred
  4 * over sockets listening on addr_any.
  5 */
  6
  7#define _GNU_SOURCE
  8
  9#include <arpa/inet.h>
 10#include <errno.h>
 11#include <error.h>
 12#include <linux/in.h>
 13#include <linux/unistd.h>
 14#include <stdbool.h>
 15#include <stdio.h>
 16#include <stdlib.h>
 17#include <string.h>
 18#include <sys/epoll.h>
 19#include <sys/types.h>
 20#include <sys/socket.h>
 21#include <unistd.h>
 22
 23static const char *IP4_ADDR = "127.0.0.1";
 24static const char *IP6_ADDR = "::1";
 25static const char *IP4_MAPPED6 = "::ffff:127.0.0.1";
 26
 27static const int PORT = 8888;
 28
 29static void build_rcv_fd(int family, int proto, int *rcv_fds, int count,
 30			 const char *addr_str)
 31{
 32	struct sockaddr_in  addr4 = {0};
 33	struct sockaddr_in6 addr6 = {0};
 34	struct sockaddr *addr;
 35	int opt, i, sz;
 36
 37	memset(&addr, 0, sizeof(addr));
 38
 39	switch (family) {
 40	case AF_INET:
 41		addr4.sin_family = family;
 42		if (!addr_str)
 43			addr4.sin_addr.s_addr = htonl(INADDR_ANY);
 44		else if (!inet_pton(family, addr_str, &addr4.sin_addr.s_addr))
 45			error(1, errno, "inet_pton failed: %s", addr_str);
 46		addr4.sin_port = htons(PORT);
 47		sz = sizeof(addr4);
 48		addr = (struct sockaddr *)&addr4;
 49		break;
 50	case AF_INET6:
 51		addr6.sin6_family = AF_INET6;
 52		if (!addr_str)
 53			addr6.sin6_addr = in6addr_any;
 54		else if (!inet_pton(family, addr_str, &addr6.sin6_addr))
 55			error(1, errno, "inet_pton failed: %s", addr_str);
 56		addr6.sin6_port = htons(PORT);
 57		sz = sizeof(addr6);
 58		addr = (struct sockaddr *)&addr6;
 59		break;
 60	default:
 61		error(1, 0, "Unsupported family %d", family);
 62		/* clang does not recognize error() above as terminating
 63		 * the program, so it complains that saddr, sz are
 64		 * not initialized when this code path is taken. Silence it.
 65		 */
 66		return;
 67	}
 68
 69	for (i = 0; i < count; ++i) {
 70		rcv_fds[i] = socket(family, proto, 0);
 71		if (rcv_fds[i] < 0)
 72			error(1, errno, "failed to create receive socket");
 73
 74		opt = 1;
 75		if (setsockopt(rcv_fds[i], SOL_SOCKET, SO_REUSEPORT, &opt,
 76			       sizeof(opt)))
 77			error(1, errno, "failed to set SO_REUSEPORT");
 78
 79		if (bind(rcv_fds[i], addr, sz))
 80			error(1, errno, "failed to bind receive socket");
 81
 82		if (proto == SOCK_STREAM && listen(rcv_fds[i], 10))
 83			error(1, errno, "tcp: failed to listen on receive port");
 84	}
 85}
 86
 87static int connect_and_send(int family, int proto)
 88{
 89	struct sockaddr_in  saddr4 = {0};
 90	struct sockaddr_in  daddr4 = {0};
 91	struct sockaddr_in6 saddr6 = {0};
 92	struct sockaddr_in6 daddr6 = {0};
 93	struct sockaddr *saddr, *daddr;
 94	int fd, sz;
 95
 96	switch (family) {
 97	case AF_INET:
 98		saddr4.sin_family = AF_INET;
 99		saddr4.sin_addr.s_addr = htonl(INADDR_ANY);
100		saddr4.sin_port = 0;
101
102		daddr4.sin_family = AF_INET;
103		if (!inet_pton(family, IP4_ADDR, &daddr4.sin_addr.s_addr))
104			error(1, errno, "inet_pton failed: %s", IP4_ADDR);
105		daddr4.sin_port = htons(PORT);
106
107		sz = sizeof(saddr4);
108		saddr = (struct sockaddr *)&saddr4;
109		daddr = (struct sockaddr *)&daddr4;
110	break;
111	case AF_INET6:
112		saddr6.sin6_family = AF_INET6;
113		saddr6.sin6_addr = in6addr_any;
114
115		daddr6.sin6_family = AF_INET6;
116		if (!inet_pton(family, IP6_ADDR, &daddr6.sin6_addr))
117			error(1, errno, "inet_pton failed: %s", IP6_ADDR);
118		daddr6.sin6_port = htons(PORT);
119
120		sz = sizeof(saddr6);
121		saddr = (struct sockaddr *)&saddr6;
122		daddr = (struct sockaddr *)&daddr6;
123	break;
124	default:
125		error(1, 0, "Unsupported family %d", family);
126		/* clang does not recognize error() above as terminating
127		 * the program, so it complains that saddr, daddr, sz are
128		 * not initialized when this code path is taken. Silence it.
129		 */
130		return -1;
131	}
132
133	fd = socket(family, proto, 0);
134	if (fd < 0)
135		error(1, errno, "failed to create send socket");
136
137	if (bind(fd, saddr, sz))
138		error(1, errno, "failed to bind send socket");
139
140	if (connect(fd, daddr, sz))
141		error(1, errno, "failed to connect send socket");
142
143	if (send(fd, "a", 1, 0) < 0)
144		error(1, errno, "failed to send message");
145
146	return fd;
147}
148
149static int receive_once(int epfd, int proto)
150{
151	struct epoll_event ev;
152	int i, fd;
153	char buf[8];
154
155	i = epoll_wait(epfd, &ev, 1, 3);
156	if (i < 0)
157		error(1, errno, "epoll_wait failed");
158
159	if (proto == SOCK_STREAM) {
160		fd = accept(ev.data.fd, NULL, NULL);
161		if (fd < 0)
162			error(1, errno, "failed to accept");
163		i = recv(fd, buf, sizeof(buf), 0);
164		close(fd);
165	} else {
166		i = recv(ev.data.fd, buf, sizeof(buf), 0);
167	}
168
169	if (i < 0)
170		error(1, errno, "failed to recv");
171
172	return ev.data.fd;
173}
174
175static void test(int *rcv_fds, int count, int family, int proto, int fd)
176{
177	struct epoll_event ev;
178	int epfd, i, send_fd, recv_fd;
179
180	epfd = epoll_create(1);
181	if (epfd < 0)
182		error(1, errno, "failed to create epoll");
183
184	ev.events = EPOLLIN;
185	for (i = 0; i < count; ++i) {
186		ev.data.fd = rcv_fds[i];
187		if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fds[i], &ev))
188			error(1, errno, "failed to register sock epoll");
189	}
190
191	send_fd = connect_and_send(family, proto);
192
193	recv_fd = receive_once(epfd, proto);
194	if (recv_fd != fd)
195		error(1, 0, "received on an unexpected socket");
196
197	close(send_fd);
198	close(epfd);
199}
200
201
202static void run_one_test(int fam_send, int fam_rcv, int proto,
203			 const char *addr_str)
204{
205	/* Below we test that a socket listening on a specific address
206	 * is always selected in preference over a socket listening
207	 * on addr_any. Bugs where this is not the case often result
208	 * in sockets created first or last to get picked. So below
209	 * we make sure that there are always addr_any sockets created
210	 * before and after a specific socket is created.
211	 */
212	int rcv_fds[10], i;
213
214	build_rcv_fd(AF_INET, proto, rcv_fds, 2, NULL);
215	build_rcv_fd(AF_INET6, proto, rcv_fds + 2, 2, NULL);
216	build_rcv_fd(fam_rcv, proto, rcv_fds + 4, 1, addr_str);
217	build_rcv_fd(AF_INET, proto, rcv_fds + 5, 2, NULL);
218	build_rcv_fd(AF_INET6, proto, rcv_fds + 7, 2, NULL);
219	test(rcv_fds, 9, fam_send, proto, rcv_fds[4]);
220	for (i = 0; i < 9; ++i)
221		close(rcv_fds[i]);
222	fprintf(stderr, "pass\n");
223}
224
225static void test_proto(int proto, const char *proto_str)
226{
227	fprintf(stderr, "%s IPv4 ... ", proto_str);
228	run_one_test(AF_INET, AF_INET, proto, IP4_ADDR);
229
230	fprintf(stderr, "%s IPv6 ... ", proto_str);
231	run_one_test(AF_INET6, AF_INET6, proto, IP6_ADDR);
232
233	fprintf(stderr, "%s IPv4 mapped to IPv6 ... ", proto_str);
234	run_one_test(AF_INET, AF_INET6, proto, IP4_MAPPED6);
235}
236
237int main(void)
238{
239	test_proto(SOCK_DGRAM, "UDP");
240	test_proto(SOCK_STREAM, "TCP");
241
242	fprintf(stderr, "SUCCESS\n");
243	return 0;
244}