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 AVL_TREE(records, avl_strcmp, true, NULL);
  46
  47 static void
  48 cache_record_free(struct cache_record *r)
  49 {
  50         DBG(2, "%s %s\n", dns_type_string(r->type), r->record);
  51         avl_delete(&records, &r->avl);
  52         free(r);
  53 }
  54
  55 static void
  56 cache_service_free(struct cache_service *s)
  57 {
  58         DBG(2, "%s\n", s->entry);
  59         avl_delete(&services, &s->avl);
  60         free(s);
  61 }
  62
  63 static int
  64 cache_is_expired(time_t t, uint32_t ttl, int frac)
  65 {
  66         if (monotonic_time() - t >= ttl * frac / 100)
  67                 return 1;
  68
  69         return 0;
  70 }
  71
  72 static void
  73 cache_gc_timer(struct uloop_timeout *timeout)
  74 {
  75         struct cache_record *r, *p;
  76         struct cache_service *s, *t;
  77
  78         avl_for_each_element_safe(&records, r, avl, p) {
  79                 if (!cache_is_expired(r->time, r->ttl, 100))
  80                         continue;
  81                 /* Records other and A(AAA) are handled as services */
  82                 if (r->type != TYPE_A && r->type != TYPE_AAAA) {
  83                         cache_record_free(r);
  84                         continue;
  85                 }
  86                 if (r->refresh >= 100) {
  87                         cache_record_free(r);
  88                         continue;
  89                 }
  90                 r->refresh += 50;
  91                 dns_send_question(r->iface, r->record, r->type, 0);
  92         }
  93
  94         avl_for_each_element_safe(&services, s, avl, t) {
  95                 if (!s->host)
  96                         continue;
  97                 if (!cache_is_expired(s->time, s->ttl, s->refresh))
  98                         continue;
  99                 if (s->refresh >= 100) {
 100                         cache_service_free(s);
 101                         continue;
 102                 }
 103                 s->refresh += 50;
 104                 if (cache_service_is_host(s))
 105                         continue;
 106                 dns_send_question(s->iface, s->entry, TYPE_PTR, 0);
 107         }
 108
 109         uloop_timeout_set(timeout, 10000);
 110 }
 111
 112 int
 113 cache_init(void)
 114 {
 115         avl_init(&services, avl_strcmp, true, NULL);
 116
 117         cache_gc.cb = cache_gc_timer;
 118         uloop_timeout_set(&cache_gc, 10000);
 119
 120         return 0;
 121 }
 122
 123 void cache_cleanup(struct interface *iface)
 124 {
 125         struct cache_record *r, *p;
 126         struct cache_service *s, *t;
 127
 128         avl_for_each_element_safe(&services, s, avl, t)
 129                 if (!iface || iface == s->iface)
 130                         cache_service_free(s);
 131
 132         avl_for_each_element_safe(&records, r, avl, p)
 133                 if (!iface || iface == r->iface)
 134                         cache_record_free(r);
 135 }
 136
 137 void
 138 cache_update(void)
 139 {
 140         struct interface *iface;
 141         struct cache_service *s;
 142
 143         vlist_for_each_element(&interfaces, iface, node)
 144                 avl_for_each_element(&services, s, avl)
 145                         dns_send_question(iface, s->entry, TYPE_PTR, 0);
 146 }
 147
 148 static struct cache_service*
 149 cache_service(struct interface *iface, char *entry, int hlen, int ttl)
 150 {
 151         struct cache_service *s, *t;
 152         char *entry_buf;
 153         char *host_buf;
 154         char *type;
 155
 156         avl_for_each_element_safe(&services, s, avl, t)
 157                 if (!strcmp(s->entry, entry)) {
 158                         s->refresh = 50;
 159                         s->time = monotonic_time();
 160                         s->ttl = ttl;
 161                         return s;
 162                 }
 163
 164         s = calloc_a(sizeof(*s),
 165                 &entry_buf, strlen(entry) + 1,
 166                 &host_buf, hlen ? hlen + 1 : 0);
 167
 168         s->avl.key = s->entry = strcpy(entry_buf, entry);
 169         s->time = monotonic_time();
 170         s->ttl = ttl;
 171         s->iface = iface;
 172         s->refresh = 50;
 173
 174         if (hlen)
 175                 s->host = strncpy(host_buf, s->entry, hlen);
 176
 177         type = strstr(entry_buf, "._");
 178         if (type)
 179                 type++;
 180         if (type)
 181                 s->avl.key = type;
 182         avl_insert(&services, &s->avl);
 183
 184         if (!hlen)
 185                 dns_send_question(iface, entry, TYPE_PTR, iface->multicast);
 186
 187         return s;
 188 }
 189
 190 static struct cache_record*
 191 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 192 {
 193         struct cache_record *l = avl_find_element(&records, record, l, avl);
 194
 195         if (!l)
 196                 return NULL;
 197
 198         while (l && l->record && !strcmp(l->record, record)) {
 199                 struct cache_record *r = l;
 200
 201                 l = avl_next_element(l, avl);
 202                 if (r->type != type)
 203                         continue;
 204
 205                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 206                         return r;
 207
 208                 if (r->port != port)
 209                         continue;
 210
 211                 if (r->rdlength != rdlength)
 212                         continue;
 213
 214                 if (!!r->rdata != !!rdata)
 215                         continue;
 216
 217                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 218                         continue;
 219
 220                 return r;
 221         }
 222
 223         return NULL;
 224 }
 225
 226 int
 227 cache_host_is_known(char *record)
 228 {
 229         struct cache_record *l = avl_find_element(&records, record, l, avl);
 230
 231         if (!l)
 232                 return 0;
 233
 234         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 235                 struct cache_record *r = l;
 236
 237                 l = avl_next_element(l, avl);
 238                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 239                         continue;
 240                 return 1;
 241         }
 242
 243         return 0;
 244 }
 245
 246 void
 247 cache_answer(struct interface *iface, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata, 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                 cache_service(iface, rdata_buffer, host_len, a->ttl);
 280
 281                 dlen = strlen(rdata_buffer) + 1;
 282                 rdata = (uint8_t*)rdata_buffer;
 283                 break;
 284
 285         case TYPE_SRV:
 286                 if (a->rdlength < 8)
 287                         return;
 288
 289                 port = be16_to_cpu(dsd->port);
 290                 memcpy(rdata_buffer, dsd, sizeof(*dsd));
 291                 if (dn_expand(base, base + blen, (const uint8_t*)&dsd[1],
 292                                 &rdata_buffer[sizeof(*dsd)], MAX_DATA_LEN - sizeof(*dsd)) < 0) {
 293                         perror("process_answer/dn_expand");
 294                         return;
 295                 }
 296                 dlen = sizeof(*dsd) + strlen(&rdata_buffer[sizeof(*dsd)]) + 1;
 297                 rdata = (uint8_t*)rdata_buffer;
 298                 break;
 299
 300         case TYPE_TXT:
 301                 rdlength = a->rdlength;
 302                 if (rdlength <= 2)
 303                         return;
 304
 305                 memcpy(rdata_buffer, &rdata[1], rdlength);
 306                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 307                 tlen = rdlength + 1;
 308                 p = &rdata_buffer[*rdata];
 309
 310                 do {
 311                         uint8_t v = *p;
 312
 313                         *p = '\0';
 314                         if (v && p + v < &rdata_buffer[rdlength])
 315                                 p += v + 1;
 316                 } while (*p);
 317                 break;
 318
 319         case TYPE_A:
 320                 cache_service(iface, name, strlen(name), a->ttl);
 321                 if (a->rdlength != 4)
 322                         return;
 323                 dlen = 4;
 324                 break;
 325
 326         case TYPE_AAAA:
 327                 cache_service(iface, name, strlen(name), a->ttl);
 328                 if (a->rdlength != 16)
 329                         return;
 330                 dlen = 16;
 331                 break;
 332
 333         default:
 334                 return;
 335         }
 336
 337         r = cache_record_find(name, a->type, port, dlen, rdata);
 338         if (r) {
 339                 if (!a->ttl) {
 340                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 341                         r->time = now + 1 - r->ttl;
 342                 } else {
 343                         r->ttl = a->ttl;
 344                         r->time = now;
 345                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 346                 }
 347                 return;
 348         }
 349
 350         if (!a->ttl)
 351                 return;
 352
 353         r = calloc_a(sizeof(*r),
 354                 &name_buf, strlen(name) + 1,
 355                 &txt_ptr, tlen,
 356                 &rdata_ptr, dlen);
 357
 358         r->avl.key = r->record = strcpy(name_buf, name);
 359         r->type = a->type;
 360         r->ttl = a->ttl;
 361         r->port = port;
 362         r->rdlength = dlen;
 363         r->time = now;
 364         r->iface = iface;
 365
 366         if (tlen)
 367                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 368
 369         if (dlen)
 370                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 371
 372         if (avl_insert(&records, &r->avl))
 373                 free(r);
 374         else
 375                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 376 }
 377
 378 void
 379 cache_dump_records(struct blob_buf *buf, const char *name)
 380 {
 381         struct cache_record *r, *last, *next;
 382         const char *txt;
 383         char buffer[INET6_ADDRSTRLEN];
 384
 385         last = avl_last_element(&records, last, avl);
 386         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 387                 switch (r->type) {
 388                 case TYPE_TXT:
 389                         if (r->txt && strlen(r->txt)) {
 390                                 txt = r->txt;
 391                                 do {
 392                                         blobmsg_add_string(buf, "txt", txt);
 393                                         txt = &txt[strlen(txt) + 1];
 394                                 } while (*txt);
 395                         }
 396                         break;
 397
 398                 case TYPE_SRV:
 399                         if (r->port)
 400                                 blobmsg_add_u32(buf, "port", r->port);
 401                         break;
 402
 403                 case TYPE_A:
 404                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 405                                 blobmsg_add_string(buf, "ipv4", buffer);
 406                         break;
 407
 408                 case TYPE_AAAA:
 409                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 410                                 blobmsg_add_string(buf, "ipv6", buffer);
 411                         break;
 412                 }
 413
 414                 if (r == last)
 415                         break;
 416
 417                 next = avl_next_element(r, avl);
 418                 if (strcmp(r->record, next->record) != 0)
 419                         break;
 420         }
 421 }
 422
 423 void
 424 cache_dump_recursive(struct blob_buf *b, const char *name, uint16_t type, struct interface *iface)
 425 {
 426         time_t now = monotonic_time();
 427         for (struct cache_record *r = avl_find_ge_element(&records, name, r, avl);
 428                         r && !strcmp(r->record, name);
 429                         r = !avl_is_last(&records, &r->avl) ? avl_next_element(r, avl) : NULL) {
 430                 int32_t ttl = r->ttl - (now - r->time);
 431                 if (ttl <= 0 || (iface && iface->ifindex != r->iface->ifindex) ||
 432                                 (type != TYPE_ANY && type != r->type))
 433                         continue;
 434
 435                 const char *txt;
 436                 char buf[INET6_ADDRSTRLEN];
 437                 void *k = blobmsg_open_table(b, NULL), *l;
 438                 const struct dns_srv_data *dsd = (const struct dns_srv_data*)r->rdata;
 439
 440                 blobmsg_add_string(b, "name", r->record);
 441                 blobmsg_add_string(b, "type", dns_type_string(r->type));
 442                 blobmsg_add_u32(b, "ttl", ttl);
 443
 444                 switch (r->type) {
 445                 case TYPE_TXT:
 446                         if ((txt = r->txt) && strlen(txt)) {
 447                                 l = blobmsg_open_array(b, "data");
 448                                 do {
 449                                         blobmsg_add_string(b, NULL, txt);
 450                                         txt = &txt[strlen(txt) + 1];
 451                                 } while (*txt);
 452                                 blobmsg_close_array(b, l);
 453                         }
 454                         break;
 455
 456                 case TYPE_SRV:
 457                         if (r->rdlength > sizeof(*dsd)) {
 458                                 blobmsg_add_u32(b, "priority", be16_to_cpu(dsd->priority));
 459                                 blobmsg_add_u32(b, "weight", be16_to_cpu(dsd->weight));
 460                                 blobmsg_add_u32(b, "port", be16_to_cpu(dsd->port));
 461                                 blobmsg_add_string(b, "target", (const char*)&dsd[1]);
 462                         }
 463                         break;
 464
 465                 case TYPE_PTR:
 466                         if (r->rdlength > 0)
 467                                 blobmsg_add_string(b, "target", (const char*)r->rdata);
 468                         break;
 469
 470                 case TYPE_A:
 471                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buf, sizeof(buf)))
 472                                 blobmsg_add_string(b, "target", buf);
 473                         break;
 474
 475                 case TYPE_AAAA:
 476                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buf, sizeof(buf)))
 477                                 blobmsg_add_string(b, "target", buf);
 478                         break;
 479                 }
 480
 481                 blobmsg_close_table(b, k);
 482
 483
 484                 if (r->type == TYPE_PTR) {
 485                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_SRV, iface);
 486                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_TXT, iface);
 487                 }
 488
 489                 if (r->type == TYPE_SRV) {
 490                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_A, iface);
 491                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_AAAA, iface);
 492                 }
 493         }
 494 }