tools/testing/selftests/net/reuseport_dualstack.c

   1 /*
   2  * It is possible to use SO_REUSEPORT to open multiple sockets bound to
   3  * equivalent local addresses using AF_INET and AF_INET6 at the same time.  If
   4  * the AF_INET6 socket has IPV6_V6ONLY set, it's clear which socket should
   5  * receive a given incoming packet.  However, when it is not set, incoming v4
   6  * packets should prefer the AF_INET socket(s).  This behavior was defined with
   7  * the original SO_REUSEPORT implementation, but broke with
   8  * e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection")
   9  * This test creates these mixed AF_INET/AF_INET6 sockets and asserts the
  10  * AF_INET preference for v4 packets.
  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
  28 static const int PORT = 8888;
  29
  30 static 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
  72 static 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
 101 static 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
 127 static 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
 157 int 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         /* NOTE: UDP socket lookups traverse a different code path when there
 176          * are > 10 sockets in a group.
 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 }