interface.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  * Copyright (C) 2014 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #define _GNU_SOURCE
  16 #include <sys/socket.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <sys/utsname.h>
  21 #include <net/if.h>
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30
  31 #include <libubox/usock.h>
  32 #include <libubox/uloop.h>
  33 #include <libubox/avl-cmp.h>
  34 #include <libubox/utils.h>
  35 #include "interface.h"
  36 #include "util.h"
  37 #include "dns.h"
  38 #include "announce.h"
  39
  40 static int
  41 interface_send_packet4(struct interface *iface, struct iovec *iov, int iov_len)
  42 {
  43         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
  44         static struct sockaddr_in a;
  45         static struct msghdr m = {
  46                 .msg_name = (struct sockaddr *) &a,
  47                 .msg_namelen = sizeof(a),
  48                 .msg_control = cmsg_data,
  49                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  50         };
  51         struct in_pktinfo *pkti;
  52         struct cmsghdr *cmsg;
  53         int fd = iface->fd.fd;
  54
  55         a.sin_family = AF_INET;
  56         a.sin_port = htons(MCAST_PORT);
  57         m.msg_iov = iov;
  58         m.msg_iovlen = iov_len;
  59
  60         memset(cmsg_data, 0, sizeof(cmsg_data));
  61         cmsg = CMSG_FIRSTHDR(&m);
  62         cmsg->cmsg_len = m.msg_controllen;
  63         cmsg->cmsg_level = IPPROTO_IP;
  64         cmsg->cmsg_type = IP_PKTINFO;
  65
  66         pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
  67         pkti->ipi_ifindex = iface->ifindex;
  68
  69         a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
  70
  71         return sendmsg(fd, &m, 0);
  72 }
  73
  74 static int
  75 interface_send_packet6(struct interface *iface, struct iovec *iov, int iov_len)
  76 {
  77         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in6_pktinfo)) / sizeof(size_t)) + 1];
  78         static struct sockaddr_in6 a;
  79         static struct msghdr m = {
  80                 .msg_name = (struct sockaddr *) &a,
  81                 .msg_namelen = sizeof(a),
  82                 .msg_control = cmsg_data,
  83                 .msg_controllen = CMSG_LEN(sizeof(struct in6_pktinfo)),
  84         };
  85         struct in6_pktinfo *pkti;
  86         struct cmsghdr *cmsg;
  87         int fd = iface->fd.fd;
  88
  89         a.sin6_family = AF_INET6;
  90         a.sin6_port = htons(MCAST_PORT);
  91         m.msg_iov = iov;
  92         m.msg_iovlen = iov_len;
  93
  94         memset(cmsg_data, 0, sizeof(cmsg_data));
  95         cmsg = CMSG_FIRSTHDR(&m);
  96         cmsg->cmsg_len = m.msg_controllen;
  97         cmsg->cmsg_level = IPPROTO_IPV6;
  98         cmsg->cmsg_type = IPV6_PKTINFO;
  99
 100         pkti = (struct in6_pktinfo*) CMSG_DATA(cmsg);
 101         pkti->ipi6_ifindex = iface->ifindex;
 102
 103         inet_pton(AF_INET6, MCAST_ADDR6, &a.sin6_addr);
 104
 105         return sendmsg(fd, &m, 0);
 106 }
 107
 108 int
 109 interface_send_packet(struct interface *iface, struct iovec *iov, int iov_len)
 110 {
 111         if (iface->v6)
 112                 return interface_send_packet6(iface, iov, iov_len);
 113
 114         return interface_send_packet4(iface, iov, iov_len);
 115 }
 116
 117 static void interface_close(struct interface *iface)
 118 {
 119         if (iface->fd.fd < 0)
 120                 return;
 121
 122         announce_free(iface);
 123         uloop_fd_delete(&iface->fd);
 124         close(iface->fd.fd);
 125         iface->fd.fd = -1;
 126 }
 127
 128 static void interface_free(struct interface *iface)
 129 {
 130         interface_close(iface);
 131         free(iface);
 132 }
 133
 134 static void
 135 read_socket(struct uloop_fd *u, unsigned int events)
 136 {
 137         struct interface *iface = container_of(u, struct interface, fd);
 138         static uint8_t buffer[8 * 1024];
 139         struct iovec iov[1];
 140         char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
 141         struct cmsghdr *cmsgptr;
 142         struct msghdr msg;
 143         socklen_t len;
 144         struct sockaddr_in6 from;
 145         int flags = 0, ifindex = -1;
 146
 147         if (u->eof) {
 148                 interface_close(iface);
 149                 uloop_timeout_set(&iface->reconnect, 1000);
 150                 return;
 151         }
 152
 153         iov[0].iov_base = buffer;
 154         iov[0].iov_len = sizeof(buffer);
 155
 156         memset(&msg, 0, sizeof(msg));
 157         msg.msg_name = (struct sockaddr *) &from;
 158         msg.msg_namelen = (iface->v6) ? (sizeof(struct sockaddr_in6)) : (sizeof(struct sockaddr_in));
 159         msg.msg_iov = iov;
 160         msg.msg_iovlen = 1;
 161         msg.msg_control = &cmsg6;
 162         msg.msg_controllen = sizeof(cmsg6);
 163
 164         len = recvmsg(u->fd, &msg, flags);
 165         if (len == -1) {
 166                 perror("read failed");
 167                 return;
 168         }
 169         for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL && ifindex == -1; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) {
 170                 void *c = CMSG_DATA(cmsgptr);
 171
 172                 if (cmsgptr->cmsg_level == IPPROTO_IP && cmsgptr->cmsg_type == IP_PKTINFO)
 173                         ifindex = ((struct in_pktinfo *) c)->ipi_ifindex;
 174                 else if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == IPV6_PKTINFO)
 175                         ifindex = ((struct in6_pktinfo *) c)->ipi6_ifindex;
 176         }
 177         if (ifindex)
 178                 dns_handle_packet(iface, buffer, len);
 179
 180         printf("%d\n", ifindex);
 181 }
 182
 183 static int
 184 interface_socket_setup4(struct interface *iface)
 185 {
 186         struct ip_mreqn mreq;
 187         uint8_t ttl = 255;
 188         int yes = 1;
 189         int no = 0;
 190         struct sockaddr_in sa = { 0 };
 191         int fd = iface->fd.fd;
 192
 193         sa.sin_family = AF_INET;
 194         sa.sin_port = htons(MCAST_PORT);
 195         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 196
 197         memset(&mreq, 0, sizeof(mreq));
 198         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 199         mreq.imr_multiaddr = sa.sin_addr;
 200         mreq.imr_ifindex = iface->ifindex;
 201
 202         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 203                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 204
 205         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 206                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 207
 208         /* Some network drivers have issues with dropping membership of
 209          * mcast groups when the iface is down, but don't allow rejoining
 210          * when it comes back up. This is an ugly workaround
 211          * -- this was copied from avahi --
 212          */
 213         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 214
 215         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 216                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 217                 close(fd);
 218                 fd = -1;
 219                 return -1;
 220         }
 221
 222         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 223                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 224
 225         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 226                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 227
 228         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 229                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 230
 231         return 0;
 232 }
 233
 234 static int
 235 interface_socket_setup6(struct interface *iface)
 236 {
 237         struct ipv6_mreq mreq;
 238         int ttl = 255;
 239         int yes = 1;
 240         int no = 0;
 241         struct sockaddr_in6 sa = { 0 };
 242         int fd = iface->fd.fd;
 243
 244         sa.sin6_family = AF_INET6;
 245         sa.sin6_port = htons(MCAST_PORT);
 246         inet_pton(AF_INET6, MCAST_ADDR6, &sa.sin6_addr);
 247
 248         memset(&mreq, 0, sizeof(mreq));
 249         mreq.ipv6mr_multiaddr = sa.sin6_addr;
 250         mreq.ipv6mr_interface = iface->ifindex;
 251
 252         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 253                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_HOPS\n");
 254
 255         if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 256                 fprintf(stderr, "ioctl failed: IPV6_UNICAST_HOPS\n");
 257
 258         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 259                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 260
 261         setsockopt(fd, IPPROTO_IPV6, IPV6_LEAVE_GROUP, &mreq, sizeof(mreq));
 262         if (setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 263                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 264                 close(fd);
 265                 fd = -1;
 266                 return -1;
 267         }
 268
 269         if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0)
 270                 fprintf(stderr, "ioctl failed: IPV6_RECVPKTINFO\n");
 271
 272         if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0)
 273                 fprintf(stderr, "ioctl failed: IPV6_RECVHOPLIMIT\n");
 274
 275         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 276                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_LOOP\n");
 277
 278         return 0;
 279 }
 280
 281 static void
 282 reconnect_socket(struct uloop_timeout *timeout)
 283 {
 284         struct interface *iface = container_of(timeout, struct interface, reconnect);
 285         char mcast_addr[16];
 286         int type = 0;
 287
 288         if (iface->v6) {
 289                 snprintf(mcast_addr, sizeof(mcast_addr), "%s%%%s", iface->mcast_addr, iface->name);
 290                 type = USOCK_IPV6ONLY;
 291         } else {
 292                 snprintf(mcast_addr, sizeof(mcast_addr), "%s", iface->mcast_addr);
 293                 type = USOCK_IPV4ONLY;
 294         }
 295
 296         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | type, mcast_addr, "5353");
 297         if (iface->fd.fd < 0) {
 298                 fprintf(stderr, "failed to add listener %s: %s\n", mcast_addr, strerror(errno));
 299                 goto retry;
 300         }
 301
 302         if (!iface->v6 && interface_socket_setup4(iface)) {
 303                 iface->fd.fd = -1;
 304                 goto retry;
 305         }
 306
 307         if (iface->v6 && interface_socket_setup6(iface)) {
 308                 iface->fd.fd = -1;
 309                 goto retry;
 310         }
 311
 312         uloop_fd_add(&iface->fd, ULOOP_READ);
 313         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 314         announce_init(iface);
 315         return;
 316
 317 retry:
 318         uloop_timeout_set(timeout, 1000);
 319 }
 320
 321
 322 static void interface_start(struct interface *iface)
 323 {
 324         iface->fd.cb = read_socket;
 325         iface->reconnect.cb = reconnect_socket;
 326         uloop_timeout_set(&iface->reconnect, 100);
 327 }
 328
 329 static void
 330 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 331                 struct vlist_node *node_old)
 332 {
 333         struct interface *iface;
 334
 335         if (node_old) {
 336                 iface = container_of(node_old, struct interface, node);
 337                 interface_free(iface);
 338         }
 339
 340         if (node_new) {
 341                 iface = container_of(node_new, struct interface, node);
 342                 interface_start(iface);
 343         }
 344 }
 345
 346 static int
 347 get_iface_ipv4(struct interface *iface)
 348 {
 349         struct sockaddr_in *sin;
 350         struct ifreq ir;
 351         int sock, ret = -1;
 352
 353         if (cfg_proto && (cfg_proto != 4))
 354                 return -1;
 355
 356         sock = socket(AF_INET, SOCK_DGRAM, 0);
 357         if (sock < 0)
 358                 return -1;
 359
 360         memset(&ir, 0, sizeof(struct ifreq));
 361         strncpy(ir.ifr_name, iface->name, sizeof(ir.ifr_name));
 362
 363         ret = ioctl(sock, SIOCGIFADDR, &ir);
 364         if (ret < 0)
 365                 goto out;
 366
 367         sin = (struct sockaddr_in *) &ir.ifr_addr;
 368         memcpy(&iface->v4_addr, &sin->sin_addr, sizeof(iface->v4_addr));
 369         iface->mcast_addr = MCAST_ADDR;
 370 out:
 371         close(sock);
 372         return ret;
 373 }
 374
 375 static int
 376 get_iface_ipv6(struct interface *iface)
 377 {
 378         struct sockaddr_in6 addr = {AF_INET6, 0, iface->ifindex, IN6ADDR_ANY_INIT, 0};
 379         socklen_t alen = sizeof(addr);
 380         int sock, ret = -1;
 381
 382         if (cfg_proto && (cfg_proto != 6))
 383                 return -1;
 384
 385         addr.sin6_addr.s6_addr[0] = 0xff;
 386         addr.sin6_addr.s6_addr[1] = 0x02;
 387         addr.sin6_addr.s6_addr[15] = 0x01;
 388
 389         sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
 390         connect(sock, (struct sockaddr*)&addr, sizeof(addr));
 391         ret = getsockname(sock, (struct sockaddr*)&addr, &alen);
 392         if (!ret) {
 393                 memcpy(&iface->v6_addr, &addr.sin6_addr, sizeof(iface->v6_addr));
 394                 iface->mcast_addr = MCAST_ADDR6;
 395                 iface->v6 = 1;
 396         }
 397         close(sock);
 398         return ret;
 399 }
 400
 401 static int _interface_add(const char *name, int v6)
 402 {
 403         struct interface *iface;
 404         char *name_buf;
 405         char *id_buf;
 406
 407         iface = calloc_a(sizeof(*iface),
 408                 &name_buf, strlen(name) + 1,
 409                 &id_buf, strlen(name) + 3);
 410
 411         sprintf(id_buf, "%d_%s", v6, name);
 412         iface->name = strcpy(name_buf, name);
 413         iface->id = id_buf;
 414         iface->ifindex = if_nametoindex(name);
 415         iface->fd.fd = -1;
 416
 417         if (iface->ifindex <= 0)
 418                 goto error;
 419
 420         if (!v6 && get_iface_ipv4(iface))
 421                 goto error;
 422
 423         if (v6 && get_iface_ipv6(iface))
 424                 goto error;
 425
 426         vlist_add(&interfaces, &iface->node, iface->id);
 427         return 0;
 428
 429 error:
 430         free(iface);
 431         return -1;
 432 }
 433
 434 int interface_add(const char *name)
 435 {
 436         int v4 = _interface_add(name, 0);
 437         int v6 = _interface_add(name, 1);
 438
 439         return v4 && v6;
 440 }
 441
 442 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);