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 static 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                         cache_record_free(r);
  81
  82         avl_for_each_element_safe(&services, s, avl, t) {
  83                 if (!s->host)
  84                         continue;
  85                 if (!cache_is_expired(s->time, s->ttl, s->refresh))
  86                         continue;
  87                 if (s->refresh >= 100) {
  88                         cache_service_free(s);
  89                         continue;
  90                 }
  91                 s->refresh += 50;
  92                 if (cache_service_is_host(s)) {
  93                         dns_send_question(s->iface, s->entry, TYPE_A, 0);
  94                         dns_send_question(s->iface, s->entry, TYPE_AAAA, 0);
  95                 } else {
  96                         dns_send_question(s->iface, s->entry, TYPE_PTR, 0);
  97                 }
  98         }
  99
 100         uloop_timeout_set(timeout, 10000);
 101 }
 102
 103 int
 104 cache_init(void)
 105 {
 106         avl_init(&services, avl_strcmp, true, NULL);
 107
 108         cache_gc.cb = cache_gc_timer;
 109         uloop_timeout_set(&cache_gc, 10000);
 110
 111         return 0;
 112 }
 113
 114 void cache_cleanup(struct interface *iface)
 115 {
 116         struct cache_record *r, *p;
 117         struct cache_service *s, *t;
 118
 119         avl_for_each_element_safe(&services, s, avl, t)
 120                 if (!iface || iface == s->iface)
 121                         cache_service_free(s);
 122
 123         avl_for_each_element_safe(&records, r, avl, p)
 124                 if (!iface || iface == r->iface)
 125                         cache_record_free(r);
 126 }
 127
 128 void
 129 cache_update(void)
 130 {
 131         struct interface *iface;
 132         struct cache_service *s;
 133
 134         vlist_for_each_element(&interfaces, iface, node)
 135                 avl_for_each_element(&services, s, avl)
 136                         dns_send_question(iface, s->entry, TYPE_PTR, 0);
 137 }
 138
 139 static struct cache_service*
 140 cache_service(struct interface *iface, char *entry, int hlen, int ttl)
 141 {
 142         struct cache_service *s, *t;
 143         char *entry_buf;
 144         char *host_buf;
 145         char *type;
 146
 147         avl_for_each_element_safe(&services, s, avl, t)
 148                 if (!strcmp(s->entry, entry)) {
 149                         s->refresh = 50;
 150                         s->time = monotonic_time();
 151                         s->ttl = ttl;
 152                         return s;
 153                 }
 154
 155         s = calloc_a(sizeof(*s),
 156                 &entry_buf, strlen(entry) + 1,
 157                 &host_buf, hlen ? hlen + 1 : 0);
 158
 159         s->avl.key = s->entry = strcpy(entry_buf, entry);
 160         s->time = monotonic_time();
 161         s->ttl = ttl;
 162         s->iface = iface;
 163         s->refresh = 50;
 164
 165         if (hlen)
 166                 s->host = strncpy(host_buf, s->entry, hlen);
 167
 168         type = strstr(entry_buf, "._");
 169         if (type)
 170                 type++;
 171         if (type)
 172                 s->avl.key = type;
 173         avl_insert(&services, &s->avl);
 174
 175         if (!hlen)
 176                 dns_send_question(iface, entry, TYPE_PTR, iface->multicast);
 177
 178         return s;
 179 }
 180
 181 static struct cache_record*
 182 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 183 {
 184         struct cache_record *l = avl_find_element(&records, record, l, avl);
 185
 186         if (!l)
 187                 return NULL;
 188
 189         while (l && l->record && !strcmp(l->record, record)) {
 190                 struct cache_record *r = l;
 191
 192                 l = avl_next_element(l, avl);
 193                 if (r->type != type)
 194                         continue;
 195
 196                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 197                         return r;
 198
 199                 if (r->port != port)
 200                         continue;
 201
 202                 if (r->rdlength != rdlength)
 203                         continue;
 204
 205                 if (!!r->rdata != !!rdata)
 206                         continue;
 207
 208                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 209                         continue;
 210
 211                 return r;
 212         }
 213
 214         return NULL;
 215 }
 216
 217 int
 218 cache_host_is_known(char *record)
 219 {
 220         struct cache_record *l = avl_find_element(&records, record, l, avl);
 221
 222         if (!l)
 223                 return 0;
 224
 225         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 226                 struct cache_record *r = l;
 227
 228                 l = avl_next_element(l, avl);
 229                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 230                         continue;
 231                 return 1;
 232         }
 233
 234         return 0;
 235 }
 236
 237 void
 238 cache_answer(struct interface *iface, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata, int flush)
 239 {
 240         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 241         struct cache_record *r;
 242         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 243         char *p = NULL;
 244         char *name_buf;
 245         void *rdata_ptr, *txt_ptr;
 246         int host_len = 0;
 247         static char *rdata_buffer = (char *) mdns_buf;
 248         time_t now = monotonic_time();
 249
 250         nlen = strlen(name);
 251
 252         switch (a->type) {
 253         case TYPE_PTR:
 254                 if (a->rdlength < 2)
 255                         return;
 256
 257                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 258                         perror("process_answer/dn_expand");
 259                         return;
 260                 }
 261
 262                 DBG(1, "A -> %s %s %s ttl:%d\n", dns_type_string(a->type), name, rdata_buffer, a->ttl);
 263
 264                 rdlength = strlen(rdata_buffer);
 265
 266                 if (strcmp(C_DNS_SD, name) != 0 &&
 267                     nlen + 1 < rdlength && !strcmp(rdata_buffer + rdlength - nlen, name))
 268                         host_len = rdlength - nlen - 1;
 269
 270                 cache_service(iface, rdata_buffer, host_len, a->ttl);
 271
 272                 dlen = strlen(rdata_buffer) + 1;
 273                 rdata = (uint8_t*)rdata_buffer;
 274                 break;
 275
 276         case TYPE_SRV:
 277                 if (a->rdlength < 8)
 278                         return;
 279
 280                 port = be16_to_cpu(dsd->port);
 281                 memcpy(rdata_buffer, dsd, sizeof(*dsd));
 282                 if (dn_expand(base, base + blen, (const uint8_t*)&dsd[1],
 283                                 &rdata_buffer[sizeof(*dsd)], MAX_DATA_LEN - sizeof(*dsd)) < 0) {
 284                         perror("process_answer/dn_expand");
 285                         return;
 286                 }
 287                 dlen = sizeof(*dsd) + strlen(&rdata_buffer[sizeof(*dsd)]) + 1;
 288                 rdata = (uint8_t*)rdata_buffer;
 289                 break;
 290
 291         case TYPE_TXT:
 292                 rdlength = a->rdlength;
 293                 if (rdlength <= 2)
 294                         return;
 295
 296                 memcpy(rdata_buffer, &rdata[1], rdlength);
 297                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 298                 tlen = rdlength + 1;
 299                 p = &rdata_buffer[*rdata];
 300
 301                 do {
 302                         uint8_t v = *p;
 303
 304                         *p = '\0';
 305                         if (v && p + v < &rdata_buffer[rdlength])
 306                                 p += v + 1;
 307                 } while (*p);
 308                 break;
 309
 310         case TYPE_A:
 311                 cache_service(iface, name, strlen(name), a->ttl);
 312                 if (a->rdlength != 4)
 313                         return;
 314                 dlen = 4;
 315                 break;
 316
 317         case TYPE_AAAA:
 318                 cache_service(iface, name, strlen(name), a->ttl);
 319                 if (a->rdlength != 16)
 320                         return;
 321                 dlen = 16;
 322                 break;
 323
 324         default:
 325                 return;
 326         }
 327
 328         r = cache_record_find(name, a->type, port, dlen, rdata);
 329         if (r) {
 330                 if (!a->ttl) {
 331                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 332                         r->time = now + 1 - r->ttl;
 333                 } else {
 334                         r->ttl = a->ttl;
 335                         r->time = now;
 336                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 337                 }
 338                 return;
 339         }
 340
 341         if (!a->ttl)
 342                 return;
 343
 344         r = calloc_a(sizeof(*r),
 345                 &name_buf, strlen(name) + 1,
 346                 &txt_ptr, tlen,
 347                 &rdata_ptr, dlen);
 348
 349         r->avl.key = r->record = strcpy(name_buf, name);
 350         r->type = a->type;
 351         r->ttl = a->ttl;
 352         r->port = port;
 353         r->rdlength = dlen;
 354         r->time = now;
 355         r->iface = iface;
 356
 357         if (tlen)
 358                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 359
 360         if (dlen)
 361                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 362
 363         if (avl_insert(&records, &r->avl))
 364                 free(r);
 365         else
 366                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 367 }
 368
 369 void
 370 cache_dump_records(struct blob_buf *buf, const char *name)
 371 {
 372         struct cache_record *r, *last, *next;
 373         const char *txt;
 374         char buffer[INET6_ADDRSTRLEN];
 375
 376         last = avl_last_element(&records, last, avl);
 377         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 378                 switch (r->type) {
 379                 case TYPE_TXT:
 380                         if (r->txt && strlen(r->txt)) {
 381                                 txt = r->txt;
 382                                 do {
 383                                         blobmsg_add_string(buf, "txt", txt);
 384                                         txt = &txt[strlen(txt) + 1];
 385                                 } while (*txt);
 386                         }
 387                         break;
 388
 389                 case TYPE_SRV:
 390                         if (r->port)
 391                                 blobmsg_add_u32(buf, "port", r->port);
 392                         break;
 393
 394                 case TYPE_A:
 395                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 396                                 blobmsg_add_string(buf, "ipv4", buffer);
 397                         break;
 398
 399                 case TYPE_AAAA:
 400                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 401                                 blobmsg_add_string(buf, "ipv6", buffer);
 402                         break;
 403                 }
 404
 405                 if (r == last)
 406                         break;
 407
 408                 next = avl_next_element(r, avl);
 409                 if (strcmp(r->record, next->record) != 0)
 410                         break;
 411         }
 412 }
 413
 414 void
 415 cache_dump_recursive(struct blob_buf *b, const char *name, uint16_t type, struct interface *iface)
 416 {
 417         time_t now = monotonic_time();
 418         for (struct cache_record *r = avl_find_ge_element(&records, name, r, avl);
 419                         r && !strcmp(r->record, name);
 420                         r = !avl_is_last(&records, &r->avl) ? avl_next_element(r, avl) : NULL) {
 421                 int32_t ttl = r->ttl - (now - r->time);
 422                 if (ttl <= 0 || (iface && iface->ifindex != r->iface->ifindex) ||
 423                                 (type != TYPE_ANY && type != r->type))
 424                         continue;
 425
 426                 const char *txt;
 427                 char buf[INET6_ADDRSTRLEN];
 428                 void *k = blobmsg_open_table(b, NULL), *l;
 429                 const struct dns_srv_data *dsd = (const struct dns_srv_data*)r->rdata;
 430
 431                 blobmsg_add_string(b, "name", r->record);
 432                 blobmsg_add_string(b, "type", dns_type_string(r->type));
 433                 blobmsg_add_u32(b, "ttl", ttl);
 434
 435                 switch (r->type) {
 436                 case TYPE_TXT:
 437                         if ((txt = r->txt) && strlen(txt)) {
 438                                 l = blobmsg_open_array(b, "data");
 439                                 do {
 440                                         blobmsg_add_string(b, NULL, txt);
 441                                         txt = &txt[strlen(txt) + 1];
 442                                 } while (*txt);
 443                                 blobmsg_close_array(b, l);
 444                         }
 445                         break;
 446
 447                 case TYPE_SRV:
 448                         if (r->rdlength > sizeof(*dsd)) {
 449                                 blobmsg_add_u32(b, "priority", be16_to_cpu(dsd->priority));
 450                                 blobmsg_add_u32(b, "weight", be16_to_cpu(dsd->weight));
 451                                 blobmsg_add_u32(b, "port", be16_to_cpu(dsd->port));
 452                                 blobmsg_add_string(b, "target", (const char*)&dsd[1]);
 453                         }
 454                         break;
 455
 456                 case TYPE_PTR:
 457                         if (r->rdlength > 0)
 458                                 blobmsg_add_string(b, "target", (const char*)r->rdata);
 459                         break;
 460
 461                 case TYPE_A:
 462                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buf, sizeof(buf)))
 463                                 blobmsg_add_string(b, "target", buf);
 464                         break;
 465
 466                 case TYPE_AAAA:
 467                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buf, sizeof(buf)))
 468                                 blobmsg_add_string(b, "target", buf);
 469                         break;
 470                 }
 471
 472                 blobmsg_close_table(b, k);
 473
 474
 475                 if (r->type == TYPE_PTR) {
 476                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_SRV, iface);
 477                         cache_dump_recursive(b, (const char*)r->rdata, TYPE_TXT, iface);
 478                 }
 479
 480                 if (r->type == TYPE_SRV) {
 481                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_A, iface);
 482                         cache_dump_recursive(b, (const char*)&dsd[1], TYPE_AAAA, iface);
 483                 }
 484         }
 485 }