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