cache.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 #define _GNU_SOURCE
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <sys/types.h>
  24 #include <sys/socket.h>
  25 #include <netinet/in.h>
  26 #include <arpa/inet.h>
  27 #include <asm/byteorder.h>
  28 #include <arpa/nameser.h>
  29 #include <resolv.h>
  30 #include <time.h>
  31
  32 #include <libubox/usock.h>
  33 #include <libubox/uloop.h>
  34 #include <libubox/avl-cmp.h>
  35 #include <libubox/blobmsg_json.h>
  36 #include <libubox/kvlist.h>
  37 #include <libubus.h>
  38
  39 #include "cache.h"
  40 #include "util.h"
  41 #include "dns.h"
  42
  43 static struct uloop_timeout cache_gc;
  44 struct avl_tree records, entries, hosts;
  45 static struct blob_buf b;
  46
  47 static struct kvlist types;
  48
  49 static void
  50 cache_record_free(struct cache_record *r, int rem)
  51 {
  52         DBG(2, "%s %s\n", dns_type_string(r->type), r->record);
  53         if (rem)
  54                 avl_delete(&records, &r->avl);
  55         free(r);
  56 }
  57
  58 static void
  59 cache_entry_free(struct cache_entry *s)
  60 {
  61         DBG(2, "%s\n", s->entry);
  62         avl_delete(&entries, &s->avl);
  63         free(s);
  64 }
  65
  66 static int
  67 cache_is_expired(time_t t, uint32_t ttl)
  68 {
  69         if (time(NULL) - t >= ttl)
  70                 return 1;
  71
  72         return 0;
  73 }
  74
  75 static void
  76 cache_gc_timer(struct uloop_timeout *timeout)
  77 {
  78         struct cache_record *r, *p;
  79         struct cache_entry *s, *t;
  80
  81         avl_for_each_element_safe(&records, r, avl, p)
  82                 if (cache_is_expired(r->time, r->ttl))
  83                         cache_record_free(r, 1);
  84
  85         avl_for_each_element_safe(&entries, s, avl, t) {
  86                 if (!s->host)
  87                         continue;
  88                 if (cache_is_expired(s->time, s->ttl))
  89                         cache_entry_free(s);
  90         }
  91
  92         uloop_timeout_set(timeout, 10000);
  93 }
  94
  95 static void
  96 cache_load_services(void)
  97 {
  98         struct blob_attr *cur;
  99         int rem;
 100
 101         blob_buf_init(&b, 0);
 102
 103         if (!blobmsg_add_json_from_file(&b, "/lib/mdns/service-types"))
 104                 return;
 105
 106         blob_for_each_attr(cur, b.head, rem)
 107                 kvlist_set(&types, blobmsg_name(cur), blobmsg_get_string(cur));
 108 }
 109
 110 char*
 111 cache_lookup_name(const char *key)
 112 {
 113         return kvlist_get(&types, key);
 114 }
 115
 116 int
 117 cache_init(void)
 118 {
 119         kvlist_init(&types, kvlist_strlen);
 120         avl_init(&entries, avl_strcmp, true, NULL);
 121         avl_init(&records, avl_strcmp, true, NULL);
 122
 123         cache_gc.cb = cache_gc_timer;
 124         uloop_timeout_set(&cache_gc, 10000);
 125         cache_load_services();
 126
 127         return 0;
 128 }
 129
 130 void cache_cleanup(void)
 131 {
 132         struct cache_record *r, *p;
 133         struct cache_entry *s, *t;
 134
 135         avl_for_each_element_safe(&records, r, avl, p)
 136                 cache_record_free(r, 1);
 137
 138         avl_for_each_element_safe(&entries, s, avl, t)
 139                 cache_entry_free(s);
 140 }
 141
 142 void
 143 cache_scan(void)
 144 {
 145         struct cache_entry *s;
 146
 147         avl_for_each_element(&entries, s, avl)
 148                 dns_send_question(&listener, s->entry, TYPE_PTR);
 149 }
 150
 151 static struct cache_entry*
 152 cache_entry(struct uloop_fd *u, char *entry, int hlen, int ttl)
 153 {
 154         struct cache_entry *s;
 155         char *entry_buf;
 156         char *host_buf;
 157         char *type;
 158
 159         s = avl_find_element(&entries, entry, s, avl);
 160         if (s)
 161                 return s;
 162
 163         s = calloc_a(sizeof(*s),
 164                 &entry_buf, strlen(entry) + 1,
 165                 &host_buf, hlen ? hlen + 1 : 0);
 166
 167         s->avl.key = s->entry = strcpy(entry_buf, entry);
 168         s->time = time(NULL);
 169         s->ttl = ttl;
 170
 171         if (hlen)
 172                 s->host = strncpy(host_buf, s->entry, hlen);
 173
 174         type = strstr(entry_buf, "._");
 175         if (type)
 176                 type++;
 177         if (type)
 178                 s->avl.key = type;
 179         avl_insert(&entries, &s->avl);
 180
 181         if (!hlen)
 182                 dns_send_question(u, entry, TYPE_PTR);
 183
 184         return s;
 185 }
 186
 187 static struct cache_record*
 188 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 189 {
 190         struct cache_record *l = avl_find_element(&records, record, l, avl);
 191
 192         if (!l)
 193                 return NULL;
 194
 195         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 196                 struct cache_record *r = l;
 197
 198                 l = avl_next_element(l, avl);
 199                 if (r->type != type)
 200                         continue;
 201
 202                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 203                         return r;
 204
 205                 if (r->port != port)
 206                         continue;
 207
 208                 if (r->rdlength != rdlength)
 209                         continue;
 210
 211                 if (!!r->rdata != !!rdata)
 212                         continue;
 213
 214                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 215                         continue;
 216
 217                 return r;
 218         }
 219
 220         return NULL;
 221 }
 222
 223 int
 224 cache_host_is_known(char *record)
 225 {
 226         struct cache_record *l = avl_find_element(&records, record, l, avl);
 227
 228         if (!l)
 229                 return 0;
 230
 231         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 232                 struct cache_record *r = l;
 233
 234                 l = avl_next_element(l, avl);
 235                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 236                         continue;
 237                 return 1;
 238         }
 239
 240         return 0;
 241 }
 242
 243 void
 244 cache_answer(struct uloop_fd *u, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata)
 245 {
 246         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 247         struct cache_record *r;
 248         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 249         char *p = NULL;
 250         char *name_buf;
 251         void *rdata_ptr, *txt_ptr;
 252
 253         if (!(a->class & CLASS_IN))
 254                 return;
 255
 256         nlen = strlen(name);
 257
 258         switch (a->type) {
 259         case TYPE_PTR:
 260                 if (a->rdlength < 2)
 261                         return;
 262
 263                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 264                         perror("process_answer/dn_expand");
 265                         return;
 266                 }
 267
 268                 DBG(1, "A -> %s %s %s\n", dns_type_string(a->type), name, rdata_buffer);
 269
 270                 rdlength = strlen(rdata_buffer);
 271
 272                 if (!strcmp(C_DNS_SD, name)) {
 273                         cache_entry(u, rdata_buffer, 0, a->ttl);
 274                         return;
 275                 }
 276
 277                 if ((rdlength < nlen) && (rdlength - nlen - 1 > 0))
 278                         return;
 279
 280                 cache_entry(u, rdata_buffer, rdlength - nlen - 1, a->ttl);
 281                 return;
 282
 283         case TYPE_SRV:
 284                 if (a->rdlength < 8)
 285                         return;
 286
 287                 port = be16_to_cpu(dsd->port);
 288                 break;
 289
 290         case TYPE_TXT:
 291                 rdlength = a->rdlength;
 292                 if (rdlength <= 2)
 293                         return;
 294
 295                 memcpy(rdata_buffer, &rdata[1], rdlength);
 296                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 297                 tlen = rdlength + 1;
 298                 p = &rdata_buffer[*rdata];
 299
 300                 do {
 301                         uint8_t v = *p;
 302
 303                         *p = '\0';
 304                         if (v)
 305                                 p += v + 1;
 306                 } while (*p);
 307                 break;
 308
 309         case TYPE_A:
 310                 cache_entry(u, name, strlen(name), a->ttl);
 311                 if (a->rdlength != 4)
 312                         return;
 313                 dlen = 4;
 314                 break;
 315
 316         case TYPE_AAAA:
 317                 cache_entry(u, name, strlen(name), a->ttl);
 318                 if (a->rdlength != 16)
 319                         return;
 320                 dlen = 16;
 321                 break;
 322
 323         default:
 324                 return;
 325         }
 326
 327         r = cache_record_find(name, a->type, port, dlen, rdata);
 328         if (r) {
 329                 if (!a->ttl) {
 330                         cache_record_free(r, 1);
 331                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 332                 } else {
 333                         r->ttl = a->ttl;
 334                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 335                 }
 336                 return;
 337         }
 338
 339         if (!a->ttl)
 340                 return;
 341
 342         r = calloc_a(sizeof(*r),
 343                 &name_buf, strlen(name) + 1,
 344                 &txt_ptr, tlen,
 345                 &rdata_ptr, dlen);
 346
 347         r->avl.key = r->record = strcpy(name_buf, name);
 348         r->type = a->type;
 349         r->ttl = a->ttl;
 350         r->port = port;
 351         r->rdlength = dlen;
 352         r->time = time(NULL);
 353
 354         if (tlen)
 355                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 356
 357         if (dlen)
 358                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 359
 360         if (avl_insert(&records, &r->avl))
 361                 free(r);
 362         else
 363                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 364 }