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 <linux/sockios.h>
  22 #include <arpa/inet.h>
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29
  30 #include <libubox/usock.h>
  31 #include <libubox/uloop.h>
  32 #include <libubox/avl-cmp.h>
  33 #include <libubox/utils.h>
  34 #include "interface.h"
  35 #include "util.h"
  36 #include "dns.h"
  37 #include "announce.h"
  38
  39 int
  40 interface_send_packet(struct interface *iface, struct iovec *iov, int iov_len)
  41 {
  42         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
  43         static struct sockaddr_in a = {
  44                 .sin_family = AF_INET,
  45                 .sin_port = htons(MCAST_PORT),
  46         };
  47         static struct msghdr m = {
  48                 .msg_name = (struct sockaddr *) &a,
  49                 .msg_namelen = sizeof(a),
  50                 .msg_control = cmsg_data,
  51                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  52         };
  53         struct in_pktinfo *pkti;
  54         struct cmsghdr *cmsg;
  55         int fd = iface->fd.fd;
  56
  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 void interface_close(struct interface *iface)
  75 {
  76         if (iface->fd.fd < 0)
  77                 return;
  78
  79         announce_free(iface);
  80         uloop_fd_delete(&iface->fd);
  81         close(iface->fd.fd);
  82         iface->fd.fd = -1;
  83 }
  84
  85 static void interface_free(struct interface *iface)
  86 {
  87         interface_close(iface);
  88         free(iface);
  89 }
  90
  91 static void
  92 read_socket(struct uloop_fd *u, unsigned int events)
  93 {
  94         struct interface *iface = container_of(u, struct interface, fd);
  95         static uint8_t buffer[8 * 1024];
  96         int len;
  97
  98         if (u->eof) {
  99                 interface_close(iface);
 100                 uloop_timeout_set(&iface->reconnect, 1000);
 101                 return;
 102         }
 103
 104         len = read(u->fd, buffer, sizeof(buffer));
 105         if (len < 1) {
 106                 fprintf(stderr, "read failed: %s\n", strerror(errno));
 107                 return;
 108         }
 109
 110         dns_handle_packet(iface, buffer, len);
 111 }
 112
 113 static int
 114 interface_socket_setup(struct interface *iface)
 115 {
 116         struct ip_mreqn mreq;
 117         uint8_t ttl = 255;
 118         int yes = 1;
 119         int no = 0;
 120         struct sockaddr_in sa = { 0 };
 121         int fd = iface->fd.fd;
 122
 123         sa.sin_family = AF_INET;
 124         sa.sin_port = htons(MCAST_PORT);
 125         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 126
 127         memset(&mreq, 0, sizeof(mreq));
 128         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 129         mreq.imr_multiaddr = sa.sin_addr;
 130         mreq.imr_ifindex = iface->ifindex;
 131
 132         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 133                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 134
 135         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 136                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 137
 138         /* Some network drivers have issues with dropping membership of
 139          * mcast groups when the iface is down, but don't allow rejoining
 140          * when it comes back up. This is an ugly workaround
 141          * -- this was copied from avahi --
 142          */
 143         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 144
 145         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 146                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 147                 close(fd);
 148                 fd = -1;
 149                 return -1;
 150         }
 151
 152         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 153                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 154
 155         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 156                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 157
 158         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 159                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 160
 161         return 0;
 162 }
 163
 164 static void
 165 reconnect_socket(struct uloop_timeout *timeout)
 166 {
 167         struct interface *iface = container_of(timeout, struct interface, reconnect);
 168
 169         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK, MCAST_ADDR, "5353");
 170         if (iface->fd.fd < 0) {
 171                 fprintf(stderr, "failed to add listener: %s\n", strerror(errno));
 172                 goto retry;
 173         }
 174
 175         if (interface_socket_setup(iface)) {
 176                 iface->fd.fd = -1;
 177                 goto retry;
 178         }
 179
 180         uloop_fd_add(&iface->fd, ULOOP_READ);
 181         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 182         announce_init(iface);
 183         return;
 184
 185 retry:
 186         uloop_timeout_set(timeout, 1000);
 187 }
 188
 189
 190 static void interface_start(struct interface *iface)
 191 {
 192         iface->fd.cb = read_socket;
 193         iface->reconnect.cb = reconnect_socket;
 194         uloop_timeout_set(&iface->reconnect, 100);
 195 }
 196
 197 static void
 198 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 199                 struct vlist_node *node_old)
 200 {
 201         struct interface *iface;
 202
 203         if (node_old) {
 204                 iface = container_of(node_old, struct interface, node);
 205                 interface_free(iface);
 206         }
 207
 208         if (node_new) {
 209                 iface = container_of(node_new, struct interface, node);
 210                 interface_start(iface);
 211         }
 212 }
 213
 214 static int
 215 get_iface_ipv4(struct interface *iface)
 216 {
 217         struct sockaddr_in *sin;
 218         struct ifreq ir;
 219         int sock, ret = -1;
 220
 221         sock = socket(AF_INET, SOCK_DGRAM, 0);
 222         if (sock < 0)
 223                 return -1;
 224
 225         memset(&ir, 0, sizeof(struct ifreq));
 226         strncpy(ir.ifr_name, iface->name, sizeof(ir.ifr_name));
 227
 228         ret = ioctl(sock, SIOCGIFADDR, &ir);
 229         if (ret < 0)
 230                 goto out;
 231
 232         sin = (struct sockaddr_in *) &ir.ifr_addr;
 233         memcpy(&iface->v4_addr, &sin->sin_addr, sizeof(iface->v4_addr));
 234
 235 out:
 236         close(sock);
 237         return ret;
 238 }
 239
 240 int interface_add(const char *name)
 241 {
 242         struct interface *iface;
 243         char *name_buf;
 244
 245         iface = calloc_a(sizeof(*iface),
 246                 &name_buf, strlen(name) + 1);
 247
 248         iface->name = strcpy(name_buf, name);
 249         iface->ifindex = if_nametoindex(name);
 250         iface->fd.fd = -1;
 251
 252         if (iface->ifindex <= 0)
 253                 goto error;
 254
 255         if (get_iface_ipv4(iface))
 256                 goto error;
 257
 258         vlist_add(&interfaces, &iface->node, name);
 259         return 0;
 260
 261 error:
 262         free(iface);
 263         return -1;
 264 }
 265
 266 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);