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, r->refresh))
  80                         continue;
  81                 /* Records other than A(AAA) are handled as services */
  82                 if (r->type != TYPE_A && r->type != TYPE_AAAA) {
  83                         if (cache_is_expired(r->time, r->ttl, 100))
  84                                 cache_record_free(r);
  85                         continue;
  86                 }
  87                 if (r->refresh >= 100) {
  88                         cache_record_free(r);
  89                         continue;
  90                 }
  91                 r->refresh += 50;
  92                 dns_send_question(r->iface, (struct sockaddr *)&r->from, r->record, r->type, 0);
  93         }
  94
  95         avl_for_each_element_safe(&services, s, avl, t) {
  96                 if (!s->host)
  97                         continue;
  98                 if (!cache_is_expired(s->time, s->ttl, s->refresh))
  99                         continue;
 100                 if (s->refresh >= 100) {
 101                         cache_service_free(s);
 102                         continue;
 103                 }
 104                 s->refresh += 50;
 105                 dns_send_question(s->iface, NULL, s->entry, TYPE_PTR, 0);
 106         }
 107
 108         uloop_timeout_set(timeout, 10000);
 109 }
 110
 111 int
 112 cache_init(void)
 113 {
 114         avl_init(&services, avl_strcmp, true, NULL);
 115
 116         cache_gc.cb = cache_gc_timer;
 117         uloop_timeout_set(&cache_gc, 10000);
 118
 119         return 0;
 120 }
 121
 122 void cache_cleanup(struct interface *iface)
 123 {
 124         struct cache_record *r, *p;
 125         struct cache_service *s, *t;
 126
 127         avl_for_each_element_safe(&services, s, avl, t)
 128                 if (!iface || iface == s->iface)
 129                         cache_service_free(s);
 130
 131         avl_for_each_element_safe(&records, r, avl, p)
 132                 if (!iface || iface == r->iface)
 133                         cache_record_free(r);
 134 }
 135
 136 void
 137 cache_update(void)
 138 {
 139         struct interface *iface;
 140         struct cache_service *s;
 141
 142         vlist_for_each_element(&interfaces, iface, node)
 143                 avl_for_each_element(&services, s, avl)
 144                         dns_send_question(iface, NULL, s->entry, TYPE_PTR, 0);
 145 }
 146
 147 static struct cache_service*
 148 cache_service(struct interface *iface, char *entry, int hlen, int ttl)
 149 {
 150         struct cache_service *s, *t;
 151         char *entry_buf;
 152         char *host_buf;
 153         char *type;
 154
 155         avl_for_each_element_safe(&services, s, avl, t)
 156                 if (!strcmp(s->entry, entry)) {
 157                         s->refresh = 50;
 158                         s->time = monotonic_time();
 159                         s->ttl = ttl;
 160                         return s;
 161                 }
 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 = monotonic_time();
 169         s->ttl = ttl;
 170         s->iface = iface;
 171         s->refresh = 50;
 172
 173         if (hlen)
 174                 s->host = strncpy(host_buf, s->entry, hlen);
 175
 176         type = strstr(entry_buf, "._");
 177         if (type)
 178                 type++;
 179         if (type)
 180                 s->avl.key = type;
 181         avl_insert(&services, &s->avl);
 182
 183         if (!hlen)
 184                 dns_send_question(iface, NULL, entry, TYPE_PTR, iface->multicast);
 185
 186         return s;
 187 }
 188
 189 static struct cache_record*
 190 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 191 {
 192         struct cache_record *l = avl_find_element(&records, record, l, avl);
 193
 194         if (!l)
 195                 return NULL;
 196
 197         while (l && l->record && !strcmp(l->record, record)) {
 198                 struct cache_record *r = l;
 199
 200                 l = avl_next_element(l, avl);
 201                 if (r->type != type)
 202                         continue;
 203
 204                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 205                         return r;
 206
 207                 if (r->port != port)
 208                         continue;
 209
 210                 if (r->rdlength != rdlength)
 211                         continue;
 212
 213                 if (!!r->rdata != !!rdata)
 214                         continue;
 215
 216                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 217                         continue;
 218
 219                 return r;
 220         }
 221
 222         return NULL;
 223 }
 224
 225 int
 226 cache_host_is_known(char *record)
 227 {
 228         struct cache_record *l = avl_find_element(&records, record, l, avl);
 229
 230         if (!l)
 231                 return 0;
 232
 233         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 234                 struct cache_record *r = l;
 235
 236                 l = avl_next_element(l, avl);
 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);
 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 (iface->v6)
 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)
 386 {
 387         struct cache_record *r, *last, *next;
 388         const char *txt;
 389         char buffer[INET6_ADDRSTRLEN];
 390
 391         last = avl_last_element(&records, last, avl);
 392         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 393                 switch (r->type) {
 394                 case TYPE_TXT:
 395                         if (r->txt && strlen(r->txt)) {
 396                                 txt = r->txt;
 397                                 do {
 398                                         blobmsg_add_string(buf, "txt", txt);
 399                                         txt = &txt[strlen(txt) + 1];
 400                                 } while (*txt);
 401                         }
 402                         break;
 403
 404                 case TYPE_SRV:
 405                         if (r->port)
 406                                 blobmsg_add_u32(buf, "port", r->port);
 407                         break;
 408
 409                 case TYPE_A:
 410                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 411                                 blobmsg_add_string(buf, "ipv4", buffer);
 412                         break;
 413
 414                 case TYPE_AAAA:
 415                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 416                                 blobmsg_add_string(buf, "ipv6", buffer);
 417                         break;
 418                 }
 419
 420                 if (r == last)
 421                         break;
 422
 423                 next = avl_next_element(r, avl);
 424                 if (strcmp(r->record, next->record) != 0)
 425                         break;
 426         }
 427 }
 428
 429 void
 430 cache_dump_recursive(struct blob_buf *b, const char *name, uint16_t type, struct interface *iface)
 431 {
 432         time_t now = monotonic_time();
 433         for (struct cache_record *r = avl_find_ge_element(&records, name, r, avl);
 434                         r && !strcmp(r->record, name);
 435                         r = !avl_is_last(&records, &r->avl) ? avl_next_element(r, avl) : NULL) {
 436                 int32_t ttl = r->ttl - (now - r->time);
 437                 if (ttl <= 0 || (iface && iface->ifindex != r->iface->ifindex) ||
 438                                 (type != TYPE_ANY && type != r->type))
 439                         continue;
 440
 441                 const char *txt;
 442                 char buf[INET6_ADDRSTRLEN];
 443                 void *k = blobmsg_open_table(b, NULL), *l;
 444                 const struct dns_srv_data *dsd = (const struct dns_srv_data*)r->rdata;
 445
 446                 blobmsg_add_string(b, "name", r->record);
 447                 blobmsg_add_string(b, "type", dns_type_string(r->type));
 448                 blobmsg_add_u32(b, "ttl", ttl);
 449
 450                 switch (r->type) {
 451                 case TYPE_TXT:
 452                         if ((txt = r->txt) && strlen(txt)) {
 453                                 l = blobmsg_open_array(b, "data");
 454                                 do {
 455                                         blobmsg_add_string(b, NULL, txt);
 456                                         txt = &txt[strlen(txt) + 1];
 457                                 } while (*txt);
 458                                 blobmsg_close_array(b, l);
 459                         }
 460                         break;
 461
 462                 case TYPE_SRV:
 463                         if (r->rdlength > sizeof(*dsd)) {
 464                                 blobmsg_add_u32(b, "priority", be16_to_cpu(dsd->priority));
 465                                 blobmsg_add_u32(b, "weight", be16_to_cpu(dsd->weight));
 466                                 blobmsg_add_u32(b, "port", be16_to_cpu(dsd->port));
 467                                 blobmsg_add_string(b, "target", (const char*)&dsd[1]);
 468                         }
 469                         break;
 470
 471                 case TYPE_PTR:
 472                         if (r->rdlength > 0)
 473                                 blobmsg_add_string(b, "target", (const char*)r->rdata);
 474                         break;
 475
 476                 case TYPE_A:
 477                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buf, sizeof(buf)))
 478                                 blobmsg_add_string(b, "target", buf);
 479                         break;
 480
 481                 case TYPE_AAAA:
 482                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buf, sizeof(buf)))
 483                                 blobmsg_add_string(b, "target", buf);
 484                         break;
 485                 }
 486
 487                 blobmsg_close_table(b, k);
 488
 489
 490                 if (r->type == TYPE_PTR) {
 491                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_SRV, iface);
 492                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_TXT, iface);
 493                 }
 494
 495                 if (r->type == TYPE_SRV) {
 496                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_A, iface);
 497                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_AAAA, iface);
 498                 }
 499         }
 500 }