1
2
3
4
5
6
7
8
9
10
11
12
13#define _GNU_SOURCE
14
15#include <arpa/inet.h>
16#include <errno.h>
17#include <error.h>
18#include <linux/in.h>
19#include <linux/unistd.h>
20#include <stdio.h>
21#include <stdlib.h>
22#include <string.h>
23#include <sys/epoll.h>
24#include <sys/types.h>
25#include <sys/socket.h>
26#include <unistd.h>
27
28static const int PORT = 8888;
29
30static void build_rcv_fd(int family, int proto, int *rcv_fds, int count)
31{
32 struct sockaddr_storage addr;
33 struct sockaddr_in *addr4;
34 struct sockaddr_in6 *addr6;
35 int opt, i;
36
37 switch (family) {
38 case AF_INET:
39 addr4 = (struct sockaddr_in *)&addr;
40 addr4->sin_family = AF_INET;
41 addr4->sin_addr.s_addr = htonl(INADDR_ANY);
42 addr4->sin_port = htons(PORT);
43 break;
44 case AF_INET6:
45 addr6 = (struct sockaddr_in6 *)&addr;
46 addr6->sin6_family = AF_INET6;
47 addr6->sin6_addr = in6addr_any;
48 addr6->sin6_port = htons(PORT);
49 break;
50 default:
51 error(1, 0, "Unsupported family %d", family);
52 }
53
54 for (i = 0; i < count; ++i) {
55 rcv_fds[i] = socket(family, proto, 0);
56 if (rcv_fds[i] < 0)
57 error(1, errno, "failed to create receive socket");
58
59 opt = 1;
60 if (setsockopt(rcv_fds[i], SOL_SOCKET, SO_REUSEPORT, &opt,
61 sizeof(opt)))
62 error(1, errno, "failed to set SO_REUSEPORT");
63
64 if (bind(rcv_fds[i], (struct sockaddr *)&addr, sizeof(addr)))
65 error(1, errno, "failed to bind receive socket");
66
67 if (proto == SOCK_STREAM && listen(rcv_fds[i], 10))
68 error(1, errno, "failed to listen on receive port");
69 }
70}
71
72static void send_from_v4(int proto)
73{
74 struct sockaddr_in saddr, daddr;
75 int fd;
76
77 saddr.sin_family = AF_INET;
78 saddr.sin_addr.s_addr = htonl(INADDR_ANY);
79 saddr.sin_port = 0;
80
81 daddr.sin_family = AF_INET;
82 daddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
83 daddr.sin_port = htons(PORT);
84
85 fd = socket(AF_INET, proto, 0);
86 if (fd < 0)
87 error(1, errno, "failed to create send socket");
88
89 if (bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)))
90 error(1, errno, "failed to bind send socket");
91
92 if (connect(fd, (struct sockaddr *)&daddr, sizeof(daddr)))
93 error(1, errno, "failed to connect send socket");
94
95 if (send(fd, "a", 1, 0) < 0)
96 error(1, errno, "failed to send message");
97
98 close(fd);
99}
100
101static int receive_once(int epfd, int proto)
102{
103 struct epoll_event ev;
104 int i, fd;
105 char buf[8];
106
107 i = epoll_wait(epfd, &ev, 1, -1);
108 if (i < 0)
109 error(1, errno, "epoll_wait failed");
110
111 if (proto == SOCK_STREAM) {
112 fd = accept(ev.data.fd, NULL, NULL);
113 if (fd < 0)
114 error(1, errno, "failed to accept");
115 i = recv(fd, buf, sizeof(buf), 0);
116 close(fd);
117 } else {
118 i = recv(ev.data.fd, buf, sizeof(buf), 0);
119 }
120
121 if (i < 0)
122 error(1, errno, "failed to recv");
123
124 return ev.data.fd;
125}
126
127static void test(int *rcv_fds, int count, int proto)
128{
129 struct epoll_event ev;
130 int epfd, i, test_fd;
131 uint16_t test_family;
132 socklen_t len;
133
134 epfd = epoll_create(1);
135 if (epfd < 0)
136 error(1, errno, "failed to create epoll");
137
138 ev.events = EPOLLIN;
139 for (i = 0; i < count; ++i) {
140 ev.data.fd = rcv_fds[i];
141 if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fds[i], &ev))
142 error(1, errno, "failed to register sock epoll");
143 }
144
145 send_from_v4(proto);
146
147 test_fd = receive_once(epfd, proto);
148 if (getsockopt(test_fd, SOL_SOCKET, SO_DOMAIN, &test_family, &len))
149 error(1, errno, "failed to read socket domain");
150 if (test_family != AF_INET)
151 error(1, 0, "expected to receive on v4 socket but got v6 (%d)",
152 test_family);
153
154 close(epfd);
155}
156
157int main(void)
158{
159 int rcv_fds[32], i;
160
161 fprintf(stderr, "---- UDP IPv4 created before IPv6 ----\n");
162 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 5);
163 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[5]), 5);
164 test(rcv_fds, 10, SOCK_DGRAM);
165 for (i = 0; i < 10; ++i)
166 close(rcv_fds[i]);
167
168 fprintf(stderr, "---- UDP IPv6 created before IPv4 ----\n");
169 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 5);
170 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[5]), 5);
171 test(rcv_fds, 10, SOCK_DGRAM);
172 for (i = 0; i < 10; ++i)
173 close(rcv_fds[i]);
174
175
176
177
178 fprintf(stderr, "---- UDP IPv4 created before IPv6 (large) ----\n");
179 build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 16);
180 build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[16]), 16);
181 test(rcv_fds, 32, SOCK_DGRAM);
182 for (i = 0; i < 32; ++i)
183 close(rcv_fds[i]);
184
185 fprintf(stderr, "---- UDP IPv6 created before IPv4 (large) ----\n");
186 build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 16);
187 build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[16]), 16);
188 test(rcv_fds, 32, SOCK_DGRAM);
189 for (i = 0; i < 32; ++i)
190 close(rcv_fds[i]);
191
192 fprintf(stderr, "---- TCP IPv4 created before IPv6 ----\n");
193 build_rcv_fd(AF_INET, SOCK_STREAM, rcv_fds, 5);
194 build_rcv_fd(AF_INET6, SOCK_STREAM, &(rcv_fds[5]), 5);
195 test(rcv_fds, 10, SOCK_STREAM);
196 for (i = 0; i < 10; ++i)
197 close(rcv_fds[i]);
198
199 fprintf(stderr, "---- TCP IPv6 created before IPv4 ----\n");
200 build_rcv_fd(AF_INET6, SOCK_STREAM, rcv_fds, 5);
201 build_rcv_fd(AF_INET, SOCK_STREAM, &(rcv_fds[5]), 5);
202 test(rcv_fds, 10, SOCK_STREAM);
203 for (i = 0; i < 10; ++i)
204 close(rcv_fds[i]);
205
206 fprintf(stderr, "SUCCESS\n");
207 return 0;
208}
209
