util.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/socket.h>
  15 #include <sys/ioctl.h>
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <sys/utsname.h>
  19 #include <linux/if.h>
  20 #include <linux/sockios.h>
  21 #include <arpa/inet.h>
  22
  23 #include <unistd.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <stdlib.h>
  29 #include <signal.h>
  30
  31 #include <libubox/uloop.h>
  32
  33 #include "dns.h"
  34 #include "util.h"
  35
  36 int debug = 0;
  37 struct uloop_fd listener;
  38
  39 static void
  40 signal_shutdown(int signal)
  41 {
  42         uloop_end();
  43 }
  44
  45 void
  46 signal_setup(void)
  47 {
  48         signal(SIGPIPE, SIG_IGN);
  49         signal(SIGTERM, signal_shutdown);
  50         signal(SIGKILL, signal_shutdown);
  51 }
  52
  53 uint32_t
  54 rand_time_delta(uint32_t t)
  55 {
  56         uint32_t val;
  57         int fd = open("/dev/urandom", O_RDONLY);
  58
  59         if (!fd)
  60                 return t;
  61
  62         if (read(fd, &val, sizeof(val)) == sizeof(val)) {
  63                 int range = t / 30;
  64
  65                 srand(val);
  66                 val = t + (rand() % range) - (range / 2);
  67         } else {
  68                 val = t;
  69         }
  70
  71         close(fd);
  72
  73         return val;
  74 }
  75
  76 const char*
  77 get_iface_ipv4(const char *ifname)
  78 {
  79         static char buffer[INET_ADDRSTRLEN];
  80         struct ifreq ir;
  81         const char *ret;
  82         int sock;
  83
  84         sock = socket(AF_INET, SOCK_DGRAM, 0);
  85         if (sock < 0)
  86                 return NULL;
  87
  88         memset(&ir, 0, sizeof(struct ifreq));
  89
  90         strncpy(ir.ifr_name, ifname, sizeof(ir.ifr_name));
  91
  92         if (ioctl(sock, SIOCGIFADDR, &ir) < 0)
  93                 return NULL;
  94
  95         ret = inet_ntop(AF_INET, &((struct sockaddr_in *) &ir.ifr_addr)->sin_addr, buffer, sizeof(buffer));
  96         close(sock);
  97
  98         return ret;
  99 }
 100
 101 int
 102 get_iface_index(const char *ifname)
 103 {
 104         struct ifreq ir;
 105         int sock;
 106
 107         sock = socket(AF_INET, SOCK_DGRAM, 0);
 108         if (sock < 0)
 109                 return 0;
 110
 111         memset(&ir, 0, sizeof(struct ifreq));
 112
 113         strncpy(ir.ifr_name, ifname, sizeof(ir.ifr_name));
 114
 115         if (ioctl(sock, SIOCGIFINDEX, &ir) < 0)
 116                 return 0;
 117
 118         close(sock);
 119
 120         return ir.ifr_ifindex;
 121 }
 122
 123 char*
 124 get_hostname(void)
 125 {
 126         static struct utsname utsname;
 127
 128         if (uname(&utsname) < 0)
 129                 return NULL;
 130
 131         return utsname.nodename;
 132 }
 133
 134 int
 135 socket_setup(int fd, const char *ip)
 136 {
 137         struct ip_mreqn mreq;
 138         uint8_t ttl = 255;
 139         int yes = 1;
 140         int no = 0;
 141         struct sockaddr_in sa = { 0 };
 142         struct in_addr in;
 143
 144         inet_aton(iface_ip, &in);
 145
 146         sa.sin_family = AF_INET;
 147         sa.sin_port = htons(MCAST_PORT);
 148         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 149
 150         memset(&mreq, 0, sizeof(mreq));
 151         mreq.imr_address.s_addr = in.s_addr;
 152         mreq.imr_multiaddr = sa.sin_addr;
 153         mreq.imr_ifindex = iface_index;
 154
 155         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 156                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 157
 158         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 159                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 160
 161         /* Some network drivers have issues with dropping membership of
 162          * mcast groups when the iface is down, but don't allow rejoining
 163          * when it comes back up. This is an ugly workaround
 164          * -- this was copied from avahi --
 165          */
 166         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 167
 168         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 169                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 170                 close(fd);
 171                 fd = -1;
 172                 return -1;
 173         }
 174
 175         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 176                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 177
 178         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 179                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 180
 181         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 182                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 183
 184         return 0;
 185 }
 186
 187 void*
 188 memdup(void *d, int l)
 189 {
 190         void *r = malloc(l);
 191         if (!r)
 192                 return NULL;
 193         memcpy(r, d, l);
 194         return r;
 195 }
 196