main.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/stat.h>
  15 #include <sys/types.h>
  16
  17 #include <time.h>
  18 #include <stdio.h>
  19 #include <fcntl.h>
  20 #include <getopt.h>
  21 #include <resolv.h>
  22 #include <unistd.h>
  23 #include <sys/types.h>
  24 #include <arpa/inet.h>
  25 #include <sys/socket.h>
  26 #include <netinet/in.h>
  27 #include <arpa/nameser.h>
  28 #include <asm/byteorder.h>
  29
  30 #include <libubus.h>
  31 #include <libubox/usock.h>
  32 #include <libubox/uloop.h>
  33 #include <libubox/avl-cmp.h>
  34
  35 #include "dns.h"
  36 #include "ubus.h"
  37 #include "util.h"
  38 #include "cache.h"
  39 #include "service.h"
  40 #include "announce.h"
  41
  42 static struct uloop_timeout reconnect;
  43 char *iface_name = "eth0";
  44 const char *iface_ip;
  45 int iface_index;
  46
  47 static int
  48 parse_answer(struct uloop_fd *u, uint8_t *buffer, int len, uint8_t **b, int *rlen, int cache)
  49 {
  50         char *name = dns_consume_name(buffer, len, b, rlen);
  51         struct dns_answer *a;
  52         uint8_t *rdata;
  53
  54         if (!name) {
  55                 fprintf(stderr, "dropping: bad question\n");
  56                 return -1;
  57         }
  58
  59         a = dns_consume_answer(b, rlen);
  60         if (!a) {
  61                 fprintf(stderr, "dropping: bad question\n");
  62                 return -1;
  63         }
  64
  65         rdata = *b;
  66         if (a->rdlength > *rlen) {
  67                 fprintf(stderr, "dropping: bad question\n");
  68                 return -1;
  69         }
  70
  71         *rlen -= a->rdlength;
  72         *b += a->rdlength;
  73
  74         if (cache)
  75                 cache_answer(u, buffer, len, name, a, rdata);
  76
  77         return 0;
  78 }
  79
  80 static void
  81 parse_question(struct uloop_fd *u, char *name, struct dns_question *q)
  82 {
  83         char *host;
  84
  85         DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name);
  86
  87         switch (q->type) {
  88         case TYPE_ANY:
  89                 host = service_name("local");
  90                 if (!strcmp(name, host))
  91                         service_reply(u, NULL);
  92                 break;
  93
  94         case TYPE_PTR:
  95                 service_announce_services(u, name);
  96                 service_reply(u, name);
  97                 break;
  98
  99         case TYPE_AAAA:
 100         case TYPE_A:
 101                 host = strstr(name, ".local");
 102                 if (host)
 103                         *host = '\0';
 104                 if (!strcmp(hostname, name))
 105                         service_reply_a(u, q->type);
 106                 break;
 107         };
 108 }
 109
 110 static void
 111 read_socket(struct uloop_fd *u, unsigned int events)
 112 {
 113         uint8_t buffer[8 * 1024];
 114         uint8_t *b = buffer;
 115         struct dns_header *h;
 116         int len, rlen;
 117
 118         if (u->eof) {
 119                 uloop_fd_delete(u);
 120                 close(u->fd);
 121                 u->fd = -1;
 122                 uloop_timeout_set(&reconnect, 1000);
 123                 return;
 124         }
 125
 126         rlen = len = read(u->fd, buffer, sizeof(buffer));
 127         if (len < 1) {
 128                 fprintf(stderr, "read failed: %s\n", strerror(errno));
 129                 return;
 130         }
 131
 132         h = dns_consume_header(&b, &rlen);
 133         if (!h) {
 134                 fprintf(stderr, "dropping: bad header\n");
 135                 return;
 136         }
 137
 138         while (h->questions-- > 0) {
 139                 char *name = dns_consume_name(buffer, len, &b, &rlen);
 140                 struct dns_question *q;
 141
 142                 if (!name) {
 143                         fprintf(stderr, "dropping: bad name\n");
 144                         return;
 145                 }
 146
 147                 q = dns_consume_question(&b, &rlen);
 148                 if (!q) {
 149                         fprintf(stderr, "dropping: bad question\n");
 150                         return;
 151                 }
 152
 153                 if (!(h->flags & FLAG_RESPONSE))
 154                         parse_question(announce_fd, name, q);
 155         }
 156
 157         if (!(h->flags & FLAG_RESPONSE))
 158                 return;
 159
 160         while (h->answers-- > 0)
 161                 parse_answer(u, buffer, len, &b, &rlen, 1);
 162
 163         while (h->authority-- > 0)
 164                 parse_answer(u, buffer, len, &b, &rlen, 0);
 165
 166         while (h->additional-- > 0)
 167                 parse_answer(u, buffer, len, &b, &rlen, 1);
 168 }
 169
 170 static void
 171 reconnect_socket(struct uloop_timeout *timeout)
 172 {
 173
 174         if (iface_ip)
 175                 listener.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK, MCAST_ADDR, "5353");
 176
 177         if (!iface_ip || listener.fd < 0) {
 178                 fprintf(stderr, "failed to add listener: %s\n", strerror(errno));
 179                 uloop_timeout_set(&reconnect, 1000);
 180         } else {
 181                 if (socket_setup(listener.fd, iface_ip)) {
 182                         uloop_timeout_set(&reconnect, 1000);
 183                         listener.fd = -1;
 184                         return;
 185                 }
 186
 187                 uloop_fd_add(&listener, ULOOP_READ);
 188                 sleep(5);
 189                 dns_send_question(&listener, "_services._dns-sd._udp.local", TYPE_PTR);
 190                 announce_init(&listener);
 191         }
 192 }
 193
 194 int
 195 main(int argc, char **argv)
 196 {
 197         int ch, ttl;
 198
 199         while ((ch = getopt(argc, argv, "h:t:i:d")) != -1) {
 200                 switch (ch) {
 201                 case 'h':
 202                         hostname = optarg;
 203                         break;
 204                 case 't':
 205                         ttl = atoi(optarg);
 206                         if (ttl > 0)
 207                                 announce_ttl = ttl;
 208                         else
 209                                 fprintf(stderr, "invalid ttl\n");
 210                         break;
 211                 case 'd':
 212                         debug++;
 213                         break;
 214                 case 'i':
 215                         iface_name = optarg;
 216                         break;
 217                 }
 218         }
 219
 220         if (!iface_name)
 221                 return -1;
 222
 223         iface_ip = get_iface_ipv4(iface_name);
 224
 225         if (!iface_ip) {
 226                 fprintf(stderr, "failed to read ip for %s\n", iface_name);
 227                 return -1;
 228         }
 229
 230         iface_index = get_iface_index(iface_name);
 231
 232         if (!iface_index) {
 233                 fprintf(stderr, "failed to read index for %s\n", iface_name);
 234                 return -1;
 235         }
 236
 237         fprintf(stderr, "interface %s has ip %s and index %d\n", iface_name, iface_ip, iface_index);
 238         signal_setup();
 239
 240         if (cache_init())
 241                 return -1;
 242
 243         service_init();
 244
 245         listener.cb = read_socket;
 246         reconnect.cb = reconnect_socket;
 247
 248         uloop_init();
 249         uloop_timeout_set(&reconnect, 100);
 250         ubus_startup();
 251         uloop_run();
 252         uloop_done();
 253
 254         cache_cleanup();
 255         service_cleanup();
 256
 257         return 0;
 258 }