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
  36 struct interface *cur_iface = NULL;
  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                 .sin_family = AF_INET,
  44                 .sin_port = htons(MCAST_PORT),
  45         };
  46         static struct msghdr m = {
  47                 .msg_name = (struct sockaddr *) &a,
  48                 .msg_namelen = sizeof(a),
  49                 .msg_control = cmsg_data,
  50                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  51         };
  52         struct in_pktinfo *pkti;
  53         struct cmsghdr *cmsg;
  54         int fd = iface->fd.fd;
  55
  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_free(struct interface *iface)
  74 {
  75         if (cur_iface == iface)
  76                 cur_iface = NULL;
  77
  78         if (iface->fd.fd >= 0) {
  79                 uloop_fd_delete(&iface->fd);
  80                 close(iface->fd.fd);
  81         }
  82         free(iface);
  83 }
  84
  85 static void interface_start(struct interface *iface)
  86 {
  87         cur_iface = iface;
  88 }
  89
  90 static void
  91 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
  92                 struct vlist_node *node_old)
  93 {
  94         struct interface *iface;
  95
  96         if (node_old) {
  97                 iface = container_of(node_old, struct interface, node);
  98                 interface_free(iface);
  99         }
 100
 101         if (node_new) {
 102                 iface = container_of(node_new, struct interface, node);
 103                 interface_start(iface);
 104         }
 105 }
 106
 107 int interface_socket_setup(struct interface *iface)
 108 {
 109         struct ip_mreqn mreq;
 110         uint8_t ttl = 255;
 111         int yes = 1;
 112         int no = 0;
 113         struct sockaddr_in sa = { 0 };
 114         struct in_addr in;
 115         int fd = iface->fd.fd;
 116
 117         inet_aton(iface->ip, &in);
 118
 119         sa.sin_family = AF_INET;
 120         sa.sin_port = htons(MCAST_PORT);
 121         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 122
 123         memset(&mreq, 0, sizeof(mreq));
 124         mreq.imr_address.s_addr = in.s_addr;
 125         mreq.imr_multiaddr = sa.sin_addr;
 126         mreq.imr_ifindex = iface->ifindex;
 127
 128         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 129                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 130
 131         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 132                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 133
 134         /* Some network drivers have issues with dropping membership of
 135          * mcast groups when the iface is down, but don't allow rejoining
 136          * when it comes back up. This is an ugly workaround
 137          * -- this was copied from avahi --
 138          */
 139         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 140
 141         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 142                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 143                 close(fd);
 144                 fd = -1;
 145                 return -1;
 146         }
 147
 148         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 149                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 150
 151         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 152                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 153
 154         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 155                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 156
 157         return 0;
 158 }
 159
 160 static const char*
 161 get_iface_ipv4(const char *ifname)
 162 {
 163         static char buffer[INET_ADDRSTRLEN];
 164         struct ifreq ir;
 165         const char *ret;
 166         int sock;
 167
 168         sock = socket(AF_INET, SOCK_DGRAM, 0);
 169         if (sock < 0)
 170                 return NULL;
 171
 172         memset(&ir, 0, sizeof(struct ifreq));
 173         strncpy(ir.ifr_name, ifname, sizeof(ir.ifr_name));
 174
 175         if (ioctl(sock, SIOCGIFADDR, &ir) < 0)
 176                 return NULL;
 177
 178         ret = inet_ntop(AF_INET, &((struct sockaddr_in *) &ir.ifr_addr)->sin_addr, buffer, sizeof(buffer));
 179         close(sock);
 180
 181         return ret;
 182 }
 183
 184 int interface_add(const char *name)
 185 {
 186         struct interface *iface;
 187         const char *ip_str;
 188         char *name_buf, *ip_buf;
 189
 190         ip_str = get_iface_ipv4(name);
 191         if (!ip_str)
 192                 return -1;
 193
 194         iface = calloc_a(sizeof(*iface),
 195                 &name_buf, strlen(name) + 1,
 196                 &ip_buf, strlen(ip_str) + 1);
 197
 198         iface->name = strcpy(name_buf, name);
 199         iface->ip = strcpy(ip_buf, ip_str);
 200         iface->ifindex = if_nametoindex(name);
 201         iface->fd.fd = -1;
 202
 203         if (iface->ifindex <= 0)
 204                 goto error;
 205
 206         vlist_add(&interfaces, &iface->node, name);
 207         return 0;
 208
 209 error:
 210         free(iface);
 211         return -1;
 212 }
 213
 214 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);