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 <libubus.h>
  37
  38 #include "cache.h"
  39 #include "util.h"
  40 #include "dns.h"
  41
  42 static struct uloop_timeout cache_gc;
  43 struct avl_tree records, entries, types, hosts;
  44 static struct blob_buf b;
  45
  46 static void
  47 cache_record_free(struct cache_record *r, int rem)
  48 {
  49         DBG(2, "%s %s\n", dns_type_string(r->type), r->record);
  50         if (rem)
  51                 avl_delete(&records, &r->avl);
  52         if (r->record)
  53                 free(r->record);
  54         if (r->rdata)
  55                 free(r->rdata);
  56         if (r->txt)
  57                 free(r->txt);
  58         free(r);
  59 }
  60
  61 static void
  62 cache_entry_free(struct cache_entry *s)
  63 {
  64         DBG(2, "%s\n", s->entry);
  65         avl_delete(&entries, &s->avl);
  66         if (s->host)
  67                 free(s->host);
  68         if (s->entry)
  69                 free(s->entry);
  70         free(s);
  71 }
  72
  73 static int
  74 cache_is_expired(time_t t, uint32_t ttl)
  75 {
  76         if (time(NULL) - t >= ttl)
  77                 return 1;
  78
  79         return 0;
  80 }
  81
  82 static void
  83 cache_gc_timer(struct uloop_timeout *timeout)
  84 {
  85         struct cache_record *r, *p;
  86         struct cache_entry *s, *t;
  87
  88         avl_for_each_element_safe(&records, r, avl, p)
  89                 if (cache_is_expired(r->time, r->ttl))
  90                         cache_record_free(r, 1);
  91
  92         avl_for_each_element_safe(&entries, s, avl, t) {
  93                 if (!s->host)
  94                         continue;
  95                 if (cache_is_expired(s->time, s->ttl))
  96                         cache_entry_free(s);
  97         }
  98
  99         uloop_timeout_set(timeout, 10000);
 100 }
 101
 102 static void
 103 cache_load_services(void)
 104 {
 105         struct blob_attr *cur;
 106         int rem;
 107
 108         blob_buf_init(&b, 0);
 109
 110         if (!blobmsg_add_json_from_file(&b, "/lib/mdns/service-types"))
 111                 return;
 112
 113         blob_for_each_attr(cur, b.head, rem) {
 114                 struct cache_type *t = malloc(sizeof(struct cache_type));
 115
 116                 if (!t)
 117                         continue;
 118                 t->avl.key = t->key = strdup(blobmsg_name(cur));
 119                 t->val = strdup(blobmsg_get_string(cur));
 120                 avl_insert(&types, &t->avl);
 121         }
 122 }
 123
 124 char*
 125 cache_lookup_name(const char *key)
 126 {
 127         struct cache_type *t;
 128
 129         t = avl_find_element(&types, key, t, avl);
 130         if (!t)
 131                 return NULL;
 132
 133         return t->val;
 134 }
 135
 136 int
 137 cache_init(void)
 138 {
 139         avl_init(&entries, avl_strcmp, true, NULL);
 140         avl_init(&types, avl_strcmp, false, NULL);
 141         avl_init(&records, avl_strcmp, true, NULL);
 142
 143         cache_gc.cb = cache_gc_timer;
 144         uloop_timeout_set(&cache_gc, 10000);
 145         cache_load_services();
 146
 147         return 0;
 148 }
 149
 150 void cache_cleanup(void)
 151 {
 152         struct cache_record *r, *p;
 153         struct cache_entry *s, *t;
 154
 155         avl_for_each_element_safe(&records, r, avl, p)
 156                 cache_record_free(r, 1);
 157
 158         avl_for_each_element_safe(&entries, s, avl, t)
 159                 cache_entry_free(s);
 160 }
 161
 162 void
 163 cache_scan(void)
 164 {
 165         struct cache_entry *s;
 166
 167         avl_for_each_element(&entries, s, avl)
 168                 dns_send_question(&listener, s->entry, TYPE_PTR);
 169 }
 170
 171 static struct cache_entry*
 172 cache_find_entry(char *entry)
 173 {
 174         struct cache_entry *s;
 175
 176         avl_for_each_element(&entries, s, avl)
 177                 if (!strcmp(s->entry, entry))
 178                         return s;
 179         return NULL;
 180 }
 181
 182 static struct cache_entry*
 183 cache_entry(struct uloop_fd *u, char *entry, int hlen, int ttl)
 184 {
 185         struct cache_entry *s;
 186         char *type;
 187
 188         s = cache_find_entry(entry);
 189         if (s)
 190                 return s;
 191
 192         s = malloc(sizeof(struct cache_entry));
 193         memset(s, 0, sizeof(struct cache_entry));
 194         s->avl.key = s->entry = strdup(entry);
 195         s->time = time(NULL);
 196         s->ttl = ttl;
 197
 198         if (hlen)
 199                 s->host = strndup(s->entry, hlen);
 200         type = strstr(s->entry, "._");
 201         if (type)
 202                 type++;
 203         if (type)
 204                 s->avl.key = type;
 205         avl_insert(&entries, &s->avl);
 206
 207         if (!hlen)
 208                 dns_send_question(u, entry, TYPE_PTR);
 209
 210         return s;
 211 }
 212
 213 static struct cache_record*
 214 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 215 {
 216         struct cache_record *l = avl_find_element(&records, record, l, avl);
 217
 218         if (!l)
 219                 return NULL;
 220
 221         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 222                 struct cache_record *r = l;
 223
 224                 l = avl_next_element(l, avl);
 225                 if (r->type != type)
 226                         continue;
 227
 228                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 229                         return r;
 230
 231                 if (r->port != port)
 232                         continue;
 233
 234                 if (r->rdlength != rdlength)
 235                         continue;
 236
 237                 if (!!r->rdata != !!rdata)
 238                         continue;
 239
 240                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 241                         continue;
 242
 243                 return r;
 244         }
 245
 246         return NULL;
 247 }
 248
 249 int
 250 cache_host_is_known(char *record)
 251 {
 252         struct cache_record *l = avl_find_element(&records, record, l, avl);
 253
 254         if (!l)
 255                 return 0;
 256
 257         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 258                 struct cache_record *r = l;
 259
 260                 l = avl_next_element(l, avl);
 261                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 262                         continue;
 263                 return 1;
 264         }
 265
 266         return 0;
 267 }
 268
 269 void
 270 cache_answer(struct uloop_fd *u, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata)
 271 {
 272         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 273         struct cache_record *r;
 274         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 275         char *p = NULL;
 276
 277         if (!(a->class & CLASS_IN))
 278                 return;
 279
 280         nlen = strlen(name);
 281
 282         switch (a->type) {
 283         case TYPE_PTR:
 284                 if (a->rdlength < 2)
 285                         return;
 286
 287                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 288                         perror("process_answer/dn_expand");
 289                         return;
 290                 }
 291
 292                 DBG(1, "A -> %s %s %s\n", dns_type_string(a->type), name, rdata_buffer);
 293
 294                 rdlength = strlen(rdata_buffer);
 295
 296                 if (!strcmp(C_DNS_SD, name)) {
 297                         cache_entry(u, rdata_buffer, 0, a->ttl);
 298                         return;
 299                 }
 300
 301                 if ((rdlength < nlen) && (rdlength - nlen - 1 > 0))
 302                         return;
 303
 304                 cache_entry(u, rdata_buffer, rdlength - nlen - 1, a->ttl);
 305                 return;
 306
 307         case TYPE_SRV:
 308                 if (a->rdlength < 8)
 309                         return;
 310
 311                 port = be16_to_cpu(dsd->port);
 312                 break;
 313
 314         case TYPE_TXT:
 315                 rdlength = a->rdlength;
 316                 if (rdlength <= 2)
 317                         return;
 318
 319                 memcpy(rdata_buffer, &rdata[1], rdlength);
 320                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 321                 tlen = rdlength + 1;
 322                 p = &rdata_buffer[*rdata];
 323
 324                 do {
 325                         uint8_t v = *p;
 326
 327                         *p = '\0';
 328                         if (v)
 329                                 p += v + 1;
 330                 } while (*p);
 331                 break;
 332
 333         case TYPE_A:
 334                 cache_entry(u, name, strlen(name), a->ttl);
 335                 if (a->rdlength != 4)
 336                         return;
 337                 dlen = 4;
 338                 break;
 339
 340         case TYPE_AAAA:
 341                 cache_entry(u, name, strlen(name), a->ttl);
 342                 if (a->rdlength != 16)
 343                         return;
 344                 dlen = 16;
 345                 break;
 346
 347         default:
 348                 return;
 349         }
 350
 351         r = cache_record_find(name, a->type, port, dlen, rdata);
 352         if (r) {
 353                 if (!a->ttl) {
 354                         cache_record_free(r, 1);
 355                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 356                 } else {
 357                         r->ttl = a->ttl;
 358                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 359                 }
 360                 return;
 361         }
 362
 363         if (!a->ttl)
 364                 return;
 365
 366         r = malloc(sizeof(struct cache_record));
 367         memset(r, 0, sizeof(struct cache_record));
 368         r->avl.key = r->record = strdup(name);
 369         r->type = a->type;
 370         r->ttl = a->ttl;
 371         r->port = port;
 372         r->rdlength = dlen;
 373         r->time = time(NULL);
 374
 375         if (tlen) {
 376                 r->txt = malloc(tlen);
 377                 if (r->txt)
 378                         memcpy(r->txt, rdata_buffer, tlen);
 379         }
 380
 381         if (dlen) {
 382                 r->rdata = malloc(dlen);
 383                 if (!r->rdata) {
 384                         cache_record_free(r, 0);
 385                         return;
 386                 }
 387                 memcpy(r->rdata, rdata, dlen);
 388         }
 389
 390         if (avl_insert(&records, &r->avl))
 391                 cache_record_free(r, 0);
 392         else
 393                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 394 }