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/avl-cmp.h>
  31 #include <libubox/utils.h>
  32 #include "interface.h"
  33 #include "util.h"
  34 #include "dns.h"
  35 #include "announce.h"
  36
  37 struct interface *cur_iface = NULL;
  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_free(struct interface *iface)
  75 {
  76         if (cur_iface == iface)
  77                 cur_iface = NULL;
  78
  79         announce_free(iface);
  80         if (iface->fd.fd >= 0) {
  81                 uloop_fd_delete(&iface->fd);
  82                 close(iface->fd.fd);
  83         }
  84         free(iface);
  85 }
  86
  87 static void interface_start(struct interface *iface)
  88 {
  89         cur_iface = iface;
  90 }
  91
  92 static void
  93 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
  94                 struct vlist_node *node_old)
  95 {
  96         struct interface *iface;
  97
  98         if (node_old) {
  99                 iface = container_of(node_old, struct interface, node);
 100                 interface_free(iface);
 101         }
 102
 103         if (node_new) {
 104                 iface = container_of(node_new, struct interface, node);
 105                 interface_start(iface);
 106         }
 107 }
 108
 109 int interface_socket_setup(struct interface *iface)
 110 {
 111         struct ip_mreqn mreq;
 112         uint8_t ttl = 255;
 113         int yes = 1;
 114         int no = 0;
 115         struct sockaddr_in sa = { 0 };
 116         struct in_addr in;
 117         int fd = iface->fd.fd;
 118
 119         inet_aton(iface->ip, &in);
 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 = in.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 const char*
 163 get_iface_ipv4(const char *ifname)
 164 {
 165         static char buffer[INET_ADDRSTRLEN];
 166         struct ifreq ir;
 167         const char *ret;
 168         int sock;
 169
 170         sock = socket(AF_INET, SOCK_DGRAM, 0);
 171         if (sock < 0)
 172                 return NULL;
 173
 174         memset(&ir, 0, sizeof(struct ifreq));
 175         strncpy(ir.ifr_name, ifname, sizeof(ir.ifr_name));
 176
 177         if (ioctl(sock, SIOCGIFADDR, &ir) < 0)
 178                 return NULL;
 179
 180         ret = inet_ntop(AF_INET, &((struct sockaddr_in *) &ir.ifr_addr)->sin_addr, buffer, sizeof(buffer));
 181         close(sock);
 182
 183         return ret;
 184 }
 185
 186 int interface_add(const char *name)
 187 {
 188         struct interface *iface;
 189         const char *ip_str;
 190         char *name_buf, *ip_buf;
 191
 192         ip_str = get_iface_ipv4(name);
 193         if (!ip_str)
 194                 return -1;
 195
 196         iface = calloc_a(sizeof(*iface),
 197                 &name_buf, strlen(name) + 1,
 198                 &ip_buf, strlen(ip_str) + 1);
 199
 200         iface->name = strcpy(name_buf, name);
 201         iface->ip = strcpy(ip_buf, ip_str);
 202         iface->ifindex = if_nametoindex(name);
 203         iface->fd.fd = -1;
 204
 205         if (iface->ifindex <= 0)
 206                 goto error;
 207
 208         vlist_add(&interfaces, &iface->node, name);
 209         return 0;
 210
 211 error:
 212         free(iface);
 213         return -1;
 214 }
 215
 216 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);