1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * It is possible to use SO_REUSEPORT to open multiple sockets bound to
4 * equivalent local addresses using AF_INET and AF_INET6 at the same time. If
5 * the AF_INET6 socket has IPV6_V6ONLY set, it's clear which socket should
6 * receive a given incoming packet. However, when it is not set, incoming v4
7 * packets should prefer the AF_INET socket(s). This behavior was defined with
8 * the original SO_REUSEPORT implementation, but broke with
9 * e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection")
10 * This test creates these mixed AF_INET/AF_INET6 sockets and asserts the
11 * AF_INET preference for v4 packets.
12 */
13
14 #define _GNU_SOURCE
15
16 #include <arpa/inet.h>
17 #include <errno.h>
18 #include <error.h>
19 #include <linux/in.h>
20 #include <linux/unistd.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/epoll.h>
25 #include <sys/types.h>
26 #include <sys/socket.h>
27 #include <unistd.h>
28
29 static const int PORT = 8888;
30
31 static void build_rcv_fd(int family, int proto, int *rcv_fds, int count)
32 {
33 struct sockaddr_storage addr;
34 struct sockaddr_in *addr4;
35 struct sockaddr_in6 *addr6;
36 int opt, i;
37
38 switch (family) {
39 case AF_INET:
40 addr4 = (struct sockaddr_in *)&addr;
41 addr4->sin_family = AF_INET;
42 addr4->sin_addr.s_addr = htonl(INADDR_ANY);
43 addr4->sin_port = htons(PORT);
44 break;
45 case AF_INET6:
46 addr6 = (struct sockaddr_in6 *)&addr;
47 addr6->sin6_family = AF_INET6;
48 addr6->sin6_addr = in6addr_any;
49 addr6->sin6_port = htons(PORT);
50 break;
51 default:
52 error(1, 0, "Unsupported family %d", family);
53 }
54
55 for (i = 0; i < count; ++i) {
56 rcv_fds[i] = socket(family, proto, 0);
57 if (rcv_fds[i] < 0)
58 error(1, errno, "failed to create receive socket");
59
60 opt = 1;
61 if (setsockopt(rcv_fds[i], SOL_SOCKET, SO_REUSEPORT, &opt,
62 sizeof(opt)))
63 error(1, errno, "failed to set SO_REUSEPORT");
64
65 if (bind(rcv_fds[i], (struct sockaddr *)&addr, sizeof(addr)))
66 error(1, errno, "failed to bind receive socket");
67
68 if (proto == SOCK_STREAM && listen(rcv_fds[i], 10))
69 error(1, errno, "failed to listen on receive port");
70 }
71 }
72
73 static void send_from_v4(int proto)
74 {
75 struct sockaddr_in saddr, daddr;
76 int fd;
77
78 saddr.sin_family = AF_INET;
79 saddr.sin_addr.s_addr = htonl(INADDR_ANY);
80 saddr.sin_port = 0;
81
82 daddr.sin_family = AF_INET;
83 daddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
84 daddr.sin_port = htons(PORT);
85
86 fd = socket(AF_INET, proto, 0);
87 if (fd < 0)
88 error(1, errno, "failed to create send socket");
89
90 if (bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)))
91 error(1, errno, "failed to bind send socket");
92
93 if (connect(fd, (struct sockaddr *)&daddr, sizeof(daddr)))
94 error(1, errno, "failed to connect send socket");
95
96 if (send(fd, "a", 1, 0) < 0)
97 error(1, errno, "failed to send message");
98
99 close(fd);
100 }
101
102 static int receive_once(int epfd, int proto)
103 {
104 struct epoll_event ev;
105 int i, fd;
106 char buf[8];
107
108 i = epoll_wait(epfd, &ev, 1, -1);
109 if (i < 0)
110 error(1, errno, "epoll_wait failed");
111
112 if (proto == SOCK_STREAM) {
113 fd = accept(ev.data.fd, NULL, NULL);
114 if (fd < 0)
115 error(1, errno, "failed to accept");
116 i = recv(fd, buf, sizeof(buf), 0);
117 close(fd);
118 } else {
119 i = recv(ev.data.fd, buf, sizeof(buf), 0);
120 }
121
122 if (i < 0)
123 error(1, errno, "failed to recv");
124
125 return ev.data.fd;
126 }
127
128 static void test(int *rcv_fds, int count, int proto)
129 {
130 struct epoll_event ev;
131 int epfd, i, test_fd;
132 int test_family;
133 socklen_t len;
134
135 epfd = epoll_create(1);
136 if (epfd < 0)
137 error(1, errno, "failed to create epoll");
138
139 ev.events = EPOLLIN;
140 for (i = 0; i < count; ++i) {
141 ev.data.fd = rcv_fds[i];
142 if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fds[i], &ev))
143 error(1, errno, "failed to register sock epoll");
144 }
145
146 send_from_v4(proto);
147
148 test_fd = receive_once(epfd, proto);
149 len = sizeof(test_family);
150 if (getsockopt(test_fd, SOL_SOCKET, SO_DOMAIN, &test_family, &len))
151 error(1, errno, "failed to read socket domain");
152 if (test_family != AF_INET)
153 error(1, 0, "expected to receive on v4 socket but got v6 (%d)",
154 test_family);
155
156 close(epfd);
157 }
158
159 int main(void)
160 {
161 int rcv_fds[32], i;
162
163 fprintf(stderr, "---- UDP IPv4 created before IPv6 ----\n");
164 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 5);
165 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[5]), 5);
166 test(rcv_fds, 10, SOCK_DGRAM);
167 for (i = 0; i < 10; ++i)
168 close(rcv_fds[i]);
169
170 fprintf(stderr, "---- UDP IPv6 created before IPv4 ----\n");
171 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 5);
172 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[5]), 5);
173 test(rcv_fds, 10, SOCK_DGRAM);
174 for (i = 0; i < 10; ++i)
175 close(rcv_fds[i]);
176
177 /* NOTE: UDP socket lookups traverse a different code path when there
178 * are > 10 sockets in a group.
179 */
180 fprintf(stderr, "---- UDP IPv4 created before IPv6 (large) ----\n");
181 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 16);
182 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[16]), 16);
183 test(rcv_fds, 32, SOCK_DGRAM);
184 for (i = 0; i < 32; ++i)
185 close(rcv_fds[i]);
186
187 fprintf(stderr, "---- UDP IPv6 created before IPv4 (large) ----\n");
188 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 16);
189 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[16]), 16);
190 test(rcv_fds, 32, SOCK_DGRAM);
191 for (i = 0; i < 32; ++i)
192 close(rcv_fds[i]);
193
194 fprintf(stderr, "---- TCP IPv4 created before IPv6 ----\n");
195 build_rcv_fd(AF_INET, SOCK_STREAM, rcv_fds, 5);
196 build_rcv_fd(AF_INET6, SOCK_STREAM, &(rcv_fds[5]), 5);
197 test(rcv_fds, 10, SOCK_STREAM);
198 for (i = 0; i < 10; ++i)
199 close(rcv_fds[i]);
200
201 fprintf(stderr, "---- TCP IPv6 created before IPv4 ----\n");
202 build_rcv_fd(AF_INET6, SOCK_STREAM, rcv_fds, 5);
203 build_rcv_fd(AF_INET, SOCK_STREAM, &(rcv_fds[5]), 5);
204 test(rcv_fds, 10, SOCK_STREAM);
205 for (i = 0; i < 10; ++i)
206 close(rcv_fds[i]);
207
208 fprintf(stderr, "SUCCESS\n");
209 return 0;
210 }
211
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