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 29static const int PORT = 8888; 30 31static 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 73static 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 102static 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 128static 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 159int 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