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         if (r->record)
  56                 free(r->record);
  57         if (r->rdata)
  58                 free(r->rdata);
  59         if (r->txt)
  60                 free(r->txt);
  61         free(r);
  62 }
  63
  64 static void
  65 cache_entry_free(struct cache_entry *s)
  66 {
  67         DBG(2, "%s\n", s->entry);
  68         avl_delete(&entries, &s->avl);
  69         if (s->host)
  70                 free(s->host);
  71         if (s->entry)
  72                 free(s->entry);
  73         free(s);
  74 }
  75
  76 static int
  77 cache_is_expired(time_t t, uint32_t ttl)
  78 {
  79         if (time(NULL) - t >= ttl)
  80                 return 1;
  81
  82         return 0;
  83 }
  84
  85 static void
  86 cache_gc_timer(struct uloop_timeout *timeout)
  87 {
  88         struct cache_record *r, *p;
  89         struct cache_entry *s, *t;
  90
  91         avl_for_each_element_safe(&records, r, avl, p)
  92                 if (cache_is_expired(r->time, r->ttl))
  93                         cache_record_free(r, 1);
  94
  95         avl_for_each_element_safe(&entries, s, avl, t) {
  96                 if (!s->host)
  97                         continue;
  98                 if (cache_is_expired(s->time, s->ttl))
  99                         cache_entry_free(s);
 100         }
 101
 102         uloop_timeout_set(timeout, 10000);
 103 }
 104
 105 static void
 106 cache_load_services(void)
 107 {
 108         struct blob_attr *cur;
 109         int rem;
 110
 111         blob_buf_init(&b, 0);
 112
 113         if (!blobmsg_add_json_from_file(&b, "/lib/mdns/service-types"))
 114                 return;
 115
 116         blob_for_each_attr(cur, b.head, rem)
 117                 kvlist_set(&types, blobmsg_name(cur), blobmsg_get_string(cur));
 118 }
 119
 120 char*
 121 cache_lookup_name(const char *key)
 122 {
 123         return kvlist_get(&types, key);
 124 }
 125
 126 int
 127 cache_init(void)
 128 {
 129         kvlist_init(&types, kvlist_strlen);
 130         avl_init(&entries, avl_strcmp, true, NULL);
 131         avl_init(&records, avl_strcmp, true, NULL);
 132
 133         cache_gc.cb = cache_gc_timer;
 134         uloop_timeout_set(&cache_gc, 10000);
 135         cache_load_services();
 136
 137         return 0;
 138 }
 139
 140 void cache_cleanup(void)
 141 {
 142         struct cache_record *r, *p;
 143         struct cache_entry *s, *t;
 144
 145         avl_for_each_element_safe(&records, r, avl, p)
 146                 cache_record_free(r, 1);
 147
 148         avl_for_each_element_safe(&entries, s, avl, t)
 149                 cache_entry_free(s);
 150 }
 151
 152 void
 153 cache_scan(void)
 154 {
 155         struct cache_entry *s;
 156
 157         avl_for_each_element(&entries, s, avl)
 158                 dns_send_question(&listener, s->entry, TYPE_PTR);
 159 }
 160
 161 static struct cache_entry*
 162 cache_entry(struct uloop_fd *u, char *entry, int hlen, int ttl)
 163 {
 164         struct cache_entry *s;
 165         char *type;
 166
 167         s = avl_find_element(&entries, entry, s, avl);
 168         if (s)
 169                 return s;
 170
 171         s = malloc(sizeof(struct cache_entry));
 172         memset(s, 0, sizeof(struct cache_entry));
 173         s->avl.key = s->entry = strdup(entry);
 174         s->time = time(NULL);
 175         s->ttl = ttl;
 176
 177         if (hlen)
 178                 s->host = strndup(s->entry, hlen);
 179         type = strstr(s->entry, "._");
 180         if (type)
 181                 type++;
 182         if (type)
 183                 s->avl.key = type;
 184         avl_insert(&entries, &s->avl);
 185
 186         if (!hlen)
 187                 dns_send_question(u, entry, TYPE_PTR);
 188
 189         return s;
 190 }
 191
 192 static struct cache_record*
 193 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 194 {
 195         struct cache_record *l = avl_find_element(&records, record, l, avl);
 196
 197         if (!l)
 198                 return NULL;
 199
 200         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 201                 struct cache_record *r = l;
 202
 203                 l = avl_next_element(l, avl);
 204                 if (r->type != type)
 205                         continue;
 206
 207                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 208                         return r;
 209
 210                 if (r->port != port)
 211                         continue;
 212
 213                 if (r->rdlength != rdlength)
 214                         continue;
 215
 216                 if (!!r->rdata != !!rdata)
 217                         continue;
 218
 219                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 220                         continue;
 221
 222                 return r;
 223         }
 224
 225         return NULL;
 226 }
 227
 228 int
 229 cache_host_is_known(char *record)
 230 {
 231         struct cache_record *l = avl_find_element(&records, record, l, avl);
 232
 233         if (!l)
 234                 return 0;
 235
 236         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 237                 struct cache_record *r = l;
 238
 239                 l = avl_next_element(l, avl);
 240                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 241                         continue;
 242                 return 1;
 243         }
 244
 245         return 0;
 246 }
 247
 248 void
 249 cache_answer(struct uloop_fd *u, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata)
 250 {
 251         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 252         struct cache_record *r;
 253         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 254         char *p = NULL;
 255
 256         if (!(a->class & CLASS_IN))
 257                 return;
 258
 259         nlen = strlen(name);
 260
 261         switch (a->type) {
 262         case TYPE_PTR:
 263                 if (a->rdlength < 2)
 264                         return;
 265
 266                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 267                         perror("process_answer/dn_expand");
 268                         return;
 269                 }
 270
 271                 DBG(1, "A -> %s %s %s\n", dns_type_string(a->type), name, rdata_buffer);
 272
 273                 rdlength = strlen(rdata_buffer);
 274
 275                 if (!strcmp(C_DNS_SD, name)) {
 276                         cache_entry(u, rdata_buffer, 0, a->ttl);
 277                         return;
 278                 }
 279
 280                 if ((rdlength < nlen) && (rdlength - nlen - 1 > 0))
 281                         return;
 282
 283                 cache_entry(u, rdata_buffer, rdlength - nlen - 1, a->ttl);
 284                 return;
 285
 286         case TYPE_SRV:
 287                 if (a->rdlength < 8)
 288                         return;
 289
 290                 port = be16_to_cpu(dsd->port);
 291                 break;
 292
 293         case TYPE_TXT:
 294                 rdlength = a->rdlength;
 295                 if (rdlength <= 2)
 296                         return;
 297
 298                 memcpy(rdata_buffer, &rdata[1], rdlength);
 299                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 300                 tlen = rdlength + 1;
 301                 p = &rdata_buffer[*rdata];
 302
 303                 do {
 304                         uint8_t v = *p;
 305
 306                         *p = '\0';
 307                         if (v)
 308                                 p += v + 1;
 309                 } while (*p);
 310                 break;
 311
 312         case TYPE_A:
 313                 cache_entry(u, name, strlen(name), a->ttl);
 314                 if (a->rdlength != 4)
 315                         return;
 316                 dlen = 4;
 317                 break;
 318
 319         case TYPE_AAAA:
 320                 cache_entry(u, name, strlen(name), a->ttl);
 321                 if (a->rdlength != 16)
 322                         return;
 323                 dlen = 16;
 324                 break;
 325
 326         default:
 327                 return;
 328         }
 329
 330         r = cache_record_find(name, a->type, port, dlen, rdata);
 331         if (r) {
 332                 if (!a->ttl) {
 333                         cache_record_free(r, 1);
 334                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 335                 } else {
 336                         r->ttl = a->ttl;
 337                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 338                 }
 339                 return;
 340         }
 341
 342         if (!a->ttl)
 343                 return;
 344
 345         r = malloc(sizeof(struct cache_record));
 346         memset(r, 0, sizeof(struct cache_record));
 347         r->avl.key = r->record = strdup(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 = malloc(tlen);
 356                 if (r->txt)
 357                         memcpy(r->txt, rdata_buffer, tlen);
 358         }
 359
 360         if (dlen) {
 361                 r->rdata = malloc(dlen);
 362                 if (!r->rdata) {
 363                         cache_record_free(r, 0);
 364                         return;
 365                 }
 366                 memcpy(r->rdata, rdata, dlen);
 367         }
 368
 369         if (avl_insert(&records, &r->avl))
 370                 cache_record_free(r, 0);
 371         else
 372                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 373 }