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