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 #include <sys/socket.h>
  16 #include <sys/ioctl.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <sys/utsname.h>
  20 #include <net/if.h>
  21 #include <arpa/inet.h>
  22
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <stdio.h>
  27 #include <errno.h>
  28
  29 #include <libubox/usock.h>
  30 #include <libubox/uloop.h>
  31 #include <libubox/avl-cmp.h>
  32 #include <libubox/utils.h>
  33 #include "interface.h"
  34 #include "util.h"
  35 #include "dns.h"
  36 #include "announce.h"
  37
  38 int
  39 interface_send_packet(struct interface *iface, struct iovec *iov, int iov_len)
  40 {
  41         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
  42         static struct sockaddr_in a;
  43         static struct msghdr m = {
  44                 .msg_name = (struct sockaddr *) &a,
  45                 .msg_namelen = sizeof(a),
  46                 .msg_control = cmsg_data,
  47                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  48         };
  49         struct in_pktinfo *pkti;
  50         struct cmsghdr *cmsg;
  51         int fd = iface->fd.fd;
  52
  53         a.sin_family = AF_INET;
  54         a.sin_port = htons(MCAST_PORT);
  55         m.msg_iov = iov;
  56         m.msg_iovlen = iov_len;
  57
  58         memset(cmsg_data, 0, sizeof(cmsg_data));
  59         cmsg = CMSG_FIRSTHDR(&m);
  60         cmsg->cmsg_len = m.msg_controllen;
  61         cmsg->cmsg_level = IPPROTO_IP;
  62         cmsg->cmsg_type = IP_PKTINFO;
  63
  64         pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
  65         pkti->ipi_ifindex = iface->ifindex;
  66
  67         a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
  68
  69         return sendmsg(fd, &m, 0);
  70 }
  71
  72 static void interface_close(struct interface *iface)
  73 {
  74         if (iface->fd.fd < 0)
  75                 return;
  76
  77         announce_free(iface);
  78         uloop_fd_delete(&iface->fd);
  79         close(iface->fd.fd);
  80         iface->fd.fd = -1;
  81 }
  82
  83 static void interface_free(struct interface *iface)
  84 {
  85         interface_close(iface);
  86         free(iface);
  87 }
  88
  89 static void
  90 read_socket(struct uloop_fd *u, unsigned int events)
  91 {
  92         struct interface *iface = container_of(u, struct interface, fd);
  93         static uint8_t buffer[8 * 1024];
  94         int len;
  95
  96         if (u->eof) {
  97                 interface_close(iface);
  98                 uloop_timeout_set(&iface->reconnect, 1000);
  99                 return;
 100         }
 101
 102         len = read(u->fd, buffer, sizeof(buffer));
 103         if (len < 1) {
 104                 fprintf(stderr, "read failed: %s\n", strerror(errno));
 105                 return;
 106         }
 107
 108         dns_handle_packet(iface, buffer, len);
 109 }
 110
 111 static int
 112 interface_socket_setup(struct interface *iface)
 113 {
 114         struct ip_mreqn mreq;
 115         uint8_t ttl = 255;
 116         int yes = 1;
 117         int no = 0;
 118         struct sockaddr_in sa = { 0 };
 119         int fd = iface->fd.fd;
 120
 121         sa.sin_family = AF_INET;
 122         sa.sin_port = htons(MCAST_PORT);
 123         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 124
 125         memset(&mreq, 0, sizeof(mreq));
 126         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 127         mreq.imr_multiaddr = sa.sin_addr;
 128         mreq.imr_ifindex = iface->ifindex;
 129
 130         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 131                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 132
 133         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 134                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 135
 136         /* Some network drivers have issues with dropping membership of
 137          * mcast groups when the iface is down, but don't allow rejoining
 138          * when it comes back up. This is an ugly workaround
 139          * -- this was copied from avahi --
 140          */
 141         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 142
 143         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 144                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 145                 close(fd);
 146                 fd = -1;
 147                 return -1;
 148         }
 149
 150         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 151                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 152
 153         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 154                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 155
 156         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 157                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 158
 159         return 0;
 160 }
 161
 162 static void
 163 reconnect_socket(struct uloop_timeout *timeout)
 164 {
 165         struct interface *iface = container_of(timeout, struct interface, reconnect);
 166
 167         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK, MCAST_ADDR, "5353");
 168         if (iface->fd.fd < 0) {
 169                 fprintf(stderr, "failed to add listener: %s\n", strerror(errno));
 170                 goto retry;
 171         }
 172
 173         if (interface_socket_setup(iface)) {
 174                 iface->fd.fd = -1;
 175                 goto retry;
 176         }
 177
 178         uloop_fd_add(&iface->fd, ULOOP_READ);
 179         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 180         announce_init(iface);
 181         return;
 182
 183 retry:
 184         uloop_timeout_set(timeout, 1000);
 185 }
 186
 187
 188 static void interface_start(struct interface *iface)
 189 {
 190         iface->fd.cb = read_socket;
 191         iface->reconnect.cb = reconnect_socket;
 192         uloop_timeout_set(&iface->reconnect, 100);
 193 }
 194
 195 static void
 196 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 197                 struct vlist_node *node_old)
 198 {
 199         struct interface *iface;
 200
 201         if (node_old) {
 202                 iface = container_of(node_old, struct interface, node);
 203                 interface_free(iface);
 204         }
 205
 206         if (node_new) {
 207                 iface = container_of(node_new, struct interface, node);
 208                 interface_start(iface);
 209         }
 210 }
 211
 212 static int
 213 get_iface_ipv4(struct interface *iface)
 214 {
 215         struct sockaddr_in *sin;
 216         struct ifreq ir;
 217         int sock, ret = -1;
 218
 219         sock = socket(AF_INET, SOCK_DGRAM, 0);
 220         if (sock < 0)
 221                 return -1;
 222
 223         memset(&ir, 0, sizeof(struct ifreq));
 224         strncpy(ir.ifr_name, iface->name, sizeof(ir.ifr_name));
 225
 226         ret = ioctl(sock, SIOCGIFADDR, &ir);
 227         if (ret < 0)
 228                 goto out;
 229
 230         sin = (struct sockaddr_in *) &ir.ifr_addr;
 231         memcpy(&iface->v4_addr, &sin->sin_addr, sizeof(iface->v4_addr));
 232
 233 out:
 234         close(sock);
 235         return ret;
 236 }
 237
 238 int interface_add(const char *name)
 239 {
 240         struct interface *iface;
 241         char *name_buf;
 242
 243         iface = calloc_a(sizeof(*iface),
 244                 &name_buf, strlen(name) + 1);
 245
 246         iface->name = strcpy(name_buf, name);
 247         iface->ifindex = if_nametoindex(name);
 248         iface->fd.fd = -1;
 249
 250         if (iface->ifindex <= 0)
 251                 goto error;
 252
 253         if (get_iface_ipv4(iface))
 254                 goto error;
 255
 256         vlist_add(&interfaces, &iface->node, name);
 257         return 0;
 258
 259 error:
 260         free(iface);
 261         return -1;
 262 }
 263
 264 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);