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 <arpa/nameser.h>
  28 #include <resolv.h>
  29 #include <time.h>
  30
  31 #include <libubox/usock.h>
  32 #include <libubox/uloop.h>
  33 #include <libubox/avl-cmp.h>
  34 #include <libubox/blobmsg_json.h>
  35 #include <libubox/kvlist.h>
  36 #include <libubus.h>
  37
  38 #include "cache.h"
  39 #include "util.h"
  40 #include "dns.h"
  41 #include "interface.h"
  42
  43 static struct uloop_timeout cache_gc;
  44 struct avl_tree services;
  45
  46 static int avl_strcasecmp(const void *k1, const void *k2, void *ptr)
  47 {
  48         return strcasecmp(k1, k2);
  49 }
  50
  51 AVL_TREE(records, avl_strcasecmp, true, NULL);
  52
  53 static void
  54 cache_record_free(struct cache_record *r)
  55 {
  56         DBG(2, "%s %s\n", dns_type_string(r->type), r->record);
  57         avl_delete(&records, &r->avl);
  58         free(r);
  59 }
  60
  61 static void
  62 cache_service_free(struct cache_service *s)
  63 {
  64         DBG(2, "%s\n", s->entry);
  65         avl_delete(&services, &s->avl);
  66         free(s);
  67 }
  68
  69 static int
  70 cache_is_expired(time_t t, uint32_t ttl, int frac)
  71 {
  72         if (monotonic_time() - t >= ttl * frac / 100)
  73                 return 1;
  74
  75         return 0;
  76 }
  77
  78 static void
  79 cache_gc_timer(struct uloop_timeout *timeout)
  80 {
  81         struct cache_record *r, *p;
  82         struct cache_service *s, *t;
  83
  84         avl_for_each_element_safe(&records, r, avl, p) {
  85                 if (!cache_is_expired(r->time, r->ttl, r->refresh))
  86                         continue;
  87                 /* Records other than A(AAA) are handled as services */
  88                 if (r->type != TYPE_A && r->type != TYPE_AAAA) {
  89                         if (cache_is_expired(r->time, r->ttl, 100))
  90                                 cache_record_free(r);
  91                         continue;
  92                 }
  93                 if (r->refresh >= 100) {
  94                         cache_record_free(r);
  95                         continue;
  96                 }
  97                 r->refresh += 50;
  98                 dns_send_question(r->iface, (struct sockaddr *)&r->from, r->record, r->type, 0);
  99         }
 100
 101         avl_for_each_element_safe(&services, s, avl, t) {
 102                 if (!s->host)
 103                         continue;
 104                 if (!cache_is_expired(s->time, s->ttl, s->refresh))
 105                         continue;
 106                 if (s->refresh >= 100) {
 107                         cache_service_free(s);
 108                         continue;
 109                 }
 110                 s->refresh += 50;
 111                 dns_send_question(s->iface, NULL, s->entry, TYPE_PTR, 0);
 112         }
 113
 114         uloop_timeout_set(timeout, 10000);
 115 }
 116
 117 int
 118 cache_init(void)
 119 {
 120         avl_init(&services, avl_strcasecmp, true, NULL);
 121
 122         cache_gc.cb = cache_gc_timer;
 123         uloop_timeout_set(&cache_gc, 10000);
 124
 125         return 0;
 126 }
 127
 128 void cache_cleanup(struct interface *iface)
 129 {
 130         struct cache_record *r, *p;
 131         struct cache_service *s, *t;
 132
 133         avl_for_each_element_safe(&services, s, avl, t)
 134                 if (!iface || iface == s->iface)
 135                         cache_service_free(s);
 136
 137         avl_for_each_element_safe(&records, r, avl, p)
 138                 if (!iface || iface == r->iface)
 139                         cache_record_free(r);
 140 }
 141
 142 void
 143 cache_update(void)
 144 {
 145         struct interface *iface;
 146         struct cache_service *s;
 147
 148         vlist_for_each_element(&interfaces, iface, node)
 149                 avl_for_each_element(&services, s, avl)
 150                         dns_send_question(iface, NULL, s->entry, TYPE_PTR, 0);
 151 }
 152
 153 static struct cache_service*
 154 cache_service(struct interface *iface, char *entry, int hlen, int ttl)
 155 {
 156         struct cache_service *s, *t;
 157         char *entry_buf;
 158         char *host_buf;
 159         char *type;
 160
 161         avl_for_each_element_safe(&services, s, avl, t)
 162                 if (!strcmp(s->entry, entry)) {
 163                         s->refresh = 50;
 164                         s->time = monotonic_time();
 165                         s->ttl = ttl;
 166                         return s;
 167                 }
 168
 169         s = calloc_a(sizeof(*s),
 170                 &entry_buf, strlen(entry) + 1,
 171                 &host_buf, hlen ? hlen + 1 : 0);
 172
 173         s->avl.key = s->entry = strcpy(entry_buf, entry);
 174         s->time = monotonic_time();
 175         s->ttl = ttl;
 176         s->iface = iface;
 177         s->refresh = 50;
 178
 179         if (hlen)
 180                 s->host = strncpy(host_buf, s->entry, hlen);
 181
 182         type = strstr(entry_buf, "._");
 183         if (type)
 184                 type++;
 185         if (type)
 186                 s->avl.key = type;
 187         avl_insert(&services, &s->avl);
 188
 189         if (!hlen)
 190                 dns_send_question(iface, NULL, entry, TYPE_PTR, interface_multicast(iface));
 191
 192         return s;
 193 }
 194
 195 static struct cache_record*
 196 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 197 {
 198         struct cache_record *l = avl_find_element(&records, record, l, avl);
 199
 200         while (l && !strcmp(l->record, record)) {
 201                 struct cache_record *r = l;
 202
 203                 l = !avl_is_last(&records, &l->avl) ? avl_next_element(l, avl) : NULL;
 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         while (l && !strcmp(l->record, record)) {
 234                 struct cache_record *r = l;
 235
 236                 l = !avl_is_last(&records, &l->avl) ? avl_next_element(l, avl) : NULL;
 237                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 238                         continue;
 239                 return 1;
 240         }
 241
 242         return 0;
 243 }
 244
 245 void cache_answer(struct interface *iface, struct sockaddr *from, uint8_t *base,
 246                   int blen, char *name, struct dns_answer *a, uint8_t *rdata,
 247                   int flush)
 248 {
 249         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 250         struct cache_record *r;
 251         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 252         char *p = NULL;
 253         char *name_buf;
 254         void *rdata_ptr, *txt_ptr;
 255         int host_len = 0;
 256         static char *rdata_buffer = (char *) mdns_buf;
 257         time_t now = monotonic_time();
 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 ttl:%d\n", dns_type_string(a->type), name, rdata_buffer, a->ttl);
 272
 273                 rdlength = strlen(rdata_buffer);
 274
 275                 if (strcmp(C_DNS_SD, name) != 0 &&
 276                     nlen + 1 < rdlength && !strcmp(rdata_buffer + rdlength - nlen, name))
 277                         host_len = rdlength - nlen - 1;
 278
 279                 if (name[0] == '_')
 280                         cache_service(iface, rdata_buffer, host_len, a->ttl);
 281
 282                 dlen = strlen(rdata_buffer) + 1;
 283                 rdata = (uint8_t*)rdata_buffer;
 284                 break;
 285
 286         case TYPE_SRV:
 287                 if (a->rdlength < 8)
 288                         return;
 289
 290                 port = be16_to_cpu(dsd->port);
 291                 memcpy(rdata_buffer, dsd, sizeof(*dsd));
 292                 if (dn_expand(base, base + blen, (const uint8_t*)&dsd[1],
 293                                 &rdata_buffer[sizeof(*dsd)], MAX_DATA_LEN - sizeof(*dsd)) < 0) {
 294                         perror("process_answer/dn_expand");
 295                         return;
 296                 }
 297                 dlen = sizeof(*dsd) + strlen(&rdata_buffer[sizeof(*dsd)]) + 1;
 298                 rdata = (uint8_t*)rdata_buffer;
 299                 break;
 300
 301         case TYPE_TXT:
 302                 rdlength = a->rdlength;
 303                 if (rdlength <= 2)
 304                         return;
 305
 306                 memcpy(rdata_buffer, &rdata[1], rdlength-1);
 307                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 308                 tlen = rdlength + 1;
 309                 p = &rdata_buffer[*rdata];
 310
 311                 do {
 312                         uint8_t v = *p;
 313
 314                         *p = '\0';
 315                         if (v && p + v < &rdata_buffer[rdlength])
 316                                 p += v + 1;
 317                 } while (*p);
 318                 break;
 319
 320         case TYPE_A:
 321                 if (a->rdlength != 4)
 322                         return;
 323                 dlen = 4;
 324                 break;
 325
 326         case TYPE_AAAA:
 327                 if (a->rdlength != 16)
 328                         return;
 329                 dlen = 16;
 330                 break;
 331
 332         default:
 333                 return;
 334         }
 335
 336         r = cache_record_find(name, a->type, port, dlen, rdata);
 337         if (r) {
 338                 if (!a->ttl) {
 339                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 340                         r->time = now + 1 - r->ttl;
 341                         r->refresh = 100;
 342                 } else {
 343                         r->ttl = a->ttl;
 344                         r->time = now;
 345                         r->refresh = 50;
 346                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 347                 }
 348                 return;
 349         }
 350
 351         if (!a->ttl)
 352                 return;
 353
 354         r = calloc_a(sizeof(*r),
 355                 &name_buf, strlen(name) + 1,
 356                 &txt_ptr, tlen,
 357                 &rdata_ptr, dlen);
 358
 359         r->avl.key = r->record = strcpy(name_buf, name);
 360         r->type = a->type;
 361         r->ttl = a->ttl;
 362         r->port = port;
 363         r->rdlength = dlen;
 364         r->time = now;
 365         r->iface = iface;
 366         if (interface_ipv6(iface))
 367                 memcpy(&r->from, from, sizeof(struct sockaddr_in6));
 368         else
 369                 memcpy(&r->from, from, sizeof(struct sockaddr_in));
 370         r->refresh = 50;
 371
 372         if (tlen)
 373                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 374
 375         if (dlen)
 376                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 377
 378         if (avl_insert(&records, &r->avl))
 379                 free(r);
 380         else
 381                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 382 }
 383
 384 void
 385 cache_dump_records(struct blob_buf *buf, const char *name, int array,
 386                    const char **hostname)
 387 {
 388         struct cache_record *r, *last, *next;
 389         const char *txt;
 390         char buffer[INET6_ADDRSTRLEN];
 391         void *c = NULL;
 392
 393         last = avl_last_element(&records, last, avl);
 394         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 395                 switch (r->type) {
 396                 case TYPE_A:
 397                         if (!c && array)
 398                                 c = blobmsg_open_array(buf, "ipv4");
 399                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 400                                 blobmsg_add_string(buf, "ipv4", buffer);
 401                         break;
 402                 }
 403
 404                 if (r == last)
 405                         break;
 406
 407                 next = avl_next_element(r, avl);
 408                 if (strcmp(r->record, next->record) != 0)
 409                         break;
 410         }
 411
 412         if (c) {
 413                 blobmsg_close_array(buf, c);
 414                 c = NULL;
 415         }
 416
 417         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 418                 switch (r->type) {
 419                 case TYPE_AAAA:
 420                         if (!c && array)
 421                                 c = blobmsg_open_array(buf, "ipv6");
 422                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 423                                 blobmsg_add_string(buf, "ipv6", buffer);
 424                         break;
 425                 }
 426
 427                 if (r == last)
 428                         break;
 429
 430                 next = avl_next_element(r, avl);
 431                 if (strcmp(r->record, next->record) != 0)
 432                         break;
 433         }
 434
 435         if (c) {
 436                 blobmsg_close_array(buf, c);
 437                 c = NULL;
 438         }
 439
 440         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 441                 switch (r->type) {
 442                 case TYPE_TXT:
 443                         if (r->txt && strlen(r->txt)) {
 444                                 if (array)
 445                                         c = blobmsg_open_array(buf, "txt");
 446
 447                                 txt = r->txt;
 448                                 do {
 449                                         blobmsg_add_string(buf, "txt", txt);
 450                                         txt = &txt[strlen(txt) + 1];
 451                                 } while (*txt);
 452                                 if (array)
 453                                         blobmsg_close_array(buf, c);
 454                         }
 455                         break;
 456
 457                 case TYPE_SRV:
 458                         if (r->rdata) {
 459                                 blobmsg_add_string(buf, "host", (char *)r->rdata + sizeof(struct dns_srv_data));
 460                                 if (hostname)
 461                                         *hostname = (char *)r->rdata + sizeof(struct dns_srv_data);
 462                         }
 463                         if (r->port)
 464                                 blobmsg_add_u32(buf, "port", r->port);
 465                         break;
 466                 }
 467
 468                 if (r == last)
 469                         break;
 470
 471                 next = avl_next_element(r, avl);
 472                 if (strcmp(r->record, next->record) != 0)
 473                         break;
 474         }
 475 }
 476
 477 void
 478 cache_dump_recursive(struct blob_buf *b, const char *name, uint16_t type, struct interface *iface)
 479 {
 480         time_t now = monotonic_time();
 481         for (struct cache_record *r = avl_find_ge_element(&records, name, r, avl);
 482                         r && !strcmp(r->record, name);
 483                         r = !avl_is_last(&records, &r->avl) ? avl_next_element(r, avl) : NULL) {
 484                 int32_t ttl = r->ttl - (now - r->time);
 485                 if (ttl <= 0 || (iface && iface->ifindex != r->iface->ifindex) ||
 486                                 (type != TYPE_ANY && type != r->type))
 487                         continue;
 488
 489                 const char *txt;
 490                 char buf[INET6_ADDRSTRLEN];
 491                 void *k = blobmsg_open_table(b, NULL), *l;
 492                 const struct dns_srv_data *dsd = (const struct dns_srv_data*)r->rdata;
 493
 494                 blobmsg_add_string(b, "name", r->record);
 495                 blobmsg_add_string(b, "type", dns_type_string(r->type));
 496                 blobmsg_add_u32(b, "ttl", ttl);
 497
 498                 switch (r->type) {
 499                 case TYPE_TXT:
 500                         if ((txt = r->txt) && strlen(txt)) {
 501                                 l = blobmsg_open_array(b, "data");
 502                                 do {
 503                                         blobmsg_add_string(b, NULL, txt);
 504                                         txt = &txt[strlen(txt) + 1];
 505                                 } while (*txt);
 506                                 blobmsg_close_array(b, l);
 507                         }
 508                         break;
 509
 510                 case TYPE_SRV:
 511                         if (r->rdlength > sizeof(*dsd)) {
 512                                 blobmsg_add_u32(b, "priority", be16_to_cpu(dsd->priority));
 513                                 blobmsg_add_u32(b, "weight", be16_to_cpu(dsd->weight));
 514                                 blobmsg_add_u32(b, "port", be16_to_cpu(dsd->port));
 515                                 blobmsg_add_string(b, "target", (const char*)&dsd[1]);
 516                         }
 517                         break;
 518
 519                 case TYPE_PTR:
 520                         if (r->rdlength > 0)
 521                                 blobmsg_add_string(b, "target", (const char*)r->rdata);
 522                         break;
 523
 524                 case TYPE_A:
 525                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buf, sizeof(buf)))
 526                                 blobmsg_add_string(b, "target", buf);
 527                         break;
 528
 529                 case TYPE_AAAA:
 530                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buf, sizeof(buf)))
 531                                 blobmsg_add_string(b, "target", buf);
 532                         break;
 533                 }
 534
 535                 blobmsg_close_table(b, k);
 536
 537
 538                 if (r->type == TYPE_PTR) {
 539                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_SRV, iface);
 540                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_TXT, iface);
 541                 }
 542
 543                 if (r->type == TYPE_SRV) {
 544                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_A, iface);
 545                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_AAAA, iface);
 546                 }
 547         }
 548 }