linux/tools/testing/selftests/net/reuseport_dualstack.c
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   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        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
 158int 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}
 210