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