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