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 uint8_t mdns_buf[MDNS_BUF_LEN];
  37 int debug = 0;
  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 char*
  77 get_hostname(void)
  78 {
  79         static struct utsname utsname;
  80
  81         if (uname(&utsname) < 0)
  82                 return NULL;
  83
  84         return utsname.nodename;
  85 }
  86
  87 void*
  88 memdup(const void *d, int l)
  89 {
  90         void *r = malloc(l);
  91         if (!r)
  92                 return NULL;
  93         memcpy(r, d, l);
  94         return r;
  95 }
  96