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 char*
 102 get_hostname(void)
 103 {
 104         static struct utsname utsname;
 105
 106         if (uname(&utsname) < 0)
 107                 return NULL;
 108
 109         return utsname.nodename;
 110 }
 111
 112 int
 113 socket_setup(int fd, const char *ip)
 114 {
 115         struct ip_mreqn mreq;
 116         uint8_t ttl = 255;
 117         int yes = 1;
 118         int no = 0;
 119         struct sockaddr_in sa;
 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 = htonl(INADDR_ANY);
 127         mreq.imr_multiaddr = sa.sin_addr;
 128
 129         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 130                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 131
 132         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 133                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 134
 135         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 136                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 137                 close(fd);
 138                 fd = -1;
 139                 return -1;
 140         }
 141
 142         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 143                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 144
 145         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 146                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 147
 148         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 149                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 150
 151         return 0;
 152 }
 153
 154 void*
 155 memdup(void *d, int l)
 156 {
 157         void *r = malloc(l);
 158         if (!r)
 159                 return NULL;
 160         memcpy(r, d, l);
 161         return r;
 162 }
 163