tools/testing/selftests/net/reuseport_dualstack.c

   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         uint16_t 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         if (getsockopt(test_fd, SOL_SOCKET, SO_DOMAIN, &test_family, &len))
 150                 error(1, errno, "failed to read socket domain");
 151         if (test_family != AF_INET)
 152                 error(1, 0, "expected to receive on v4 socket but got v6 (%d)",
 153                       test_family);
 154
 155         close(epfd);
 156 }
 157
 158 int main(void)
 159 {
 160         int rcv_fds[32], i;
 161
 162         fprintf(stderr, "---- UDP IPv4 created before IPv6 ----\n");
 163         build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 5);
 164         build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[5]), 5);
 165         test(rcv_fds, 10, SOCK_DGRAM);
 166         for (i = 0; i < 10; ++i)
 167                 close(rcv_fds[i]);
 168
 169         fprintf(stderr, "---- UDP IPv6 created before IPv4 ----\n");
 170         build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 5);
 171         build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[5]), 5);
 172         test(rcv_fds, 10, SOCK_DGRAM);
 173         for (i = 0; i < 10; ++i)
 174                 close(rcv_fds[i]);
 175
 176         /* NOTE: UDP socket lookups traverse a different code path when there
 177          * are > 10 sockets in a group.
 178          */
 179         fprintf(stderr, "---- UDP IPv4 created before IPv6 (large) ----\n");
 180         build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 16);
 181         build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[16]), 16);
 182         test(rcv_fds, 32, SOCK_DGRAM);
 183         for (i = 0; i < 32; ++i)
 184                 close(rcv_fds[i]);
 185
 186         fprintf(stderr, "---- UDP IPv6 created before IPv4 (large) ----\n");
 187         build_rcv_fd(AF_INET6, SOCK_DGRAM, rcv_fds, 16);
 188         build_rcv_fd(AF_INET, SOCK_DGRAM, &(rcv_fds[16]), 16);
 189         test(rcv_fds, 32, SOCK_DGRAM);
 190         for (i = 0; i < 32; ++i)
 191                 close(rcv_fds[i]);
 192
 193         fprintf(stderr, "---- TCP IPv4 created before IPv6 ----\n");
 194         build_rcv_fd(AF_INET, SOCK_STREAM, rcv_fds, 5);
 195         build_rcv_fd(AF_INET6, SOCK_STREAM, &(rcv_fds[5]), 5);
 196         test(rcv_fds, 10, SOCK_STREAM);
 197         for (i = 0; i < 10; ++i)
 198                 close(rcv_fds[i]);
 199
 200         fprintf(stderr, "---- TCP IPv6 created before IPv4 ----\n");
 201         build_rcv_fd(AF_INET6, SOCK_STREAM, rcv_fds, 5);
 202         build_rcv_fd(AF_INET, SOCK_STREAM, &(rcv_fds[5]), 5);
 203         test(rcv_fds, 10, SOCK_STREAM);
 204         for (i = 0; i < 10; ++i)
 205                 close(rcv_fds[i]);
 206
 207         fprintf(stderr, "SUCCESS\n");
 208         return 0;
 209 }