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 (time(NULL) - 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, 1);
  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, 1);
 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 = time(NULL);
 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 = time(NULL);
 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
 243         nlen = strlen(name);
 244
 245         switch (a->type) {
 246         case TYPE_PTR:
 247                 if (a->rdlength < 2)
 248                         return;
 249
 250                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 251                         perror("process_answer/dn_expand");
 252                         return;
 253                 }
 254
 255                 DBG(1, "A -> %s %s %s ttl:%d\n", dns_type_string(a->type), name, rdata_buffer, a->ttl);
 256
 257                 rdlength = strlen(rdata_buffer);
 258
 259                 if (strcmp(C_DNS_SD, name) != 0 &&
 260                     nlen + 1 < rdlength && !strcmp(rdata_buffer + rdlength - nlen, name))
 261                         host_len = rdlength - nlen - 1;
 262
 263                 cache_service(iface, rdata_buffer, host_len, a->ttl);
 264                 return;
 265
 266         case TYPE_SRV:
 267                 if (a->rdlength < 8)
 268                         return;
 269
 270                 port = be16_to_cpu(dsd->port);
 271                 break;
 272
 273         case TYPE_TXT:
 274                 rdlength = a->rdlength;
 275                 if (rdlength <= 2)
 276                         return;
 277
 278                 memcpy(rdata_buffer, &rdata[1], rdlength);
 279                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 280                 tlen = rdlength + 1;
 281                 p = &rdata_buffer[*rdata];
 282
 283                 do {
 284                         uint8_t v = *p;
 285
 286                         *p = '\0';
 287                         if (v && p + v < &rdata_buffer[rdlength])
 288                                 p += v + 1;
 289                 } while (*p);
 290                 break;
 291
 292         case TYPE_A:
 293                 cache_service(iface, name, strlen(name), a->ttl);
 294                 if (a->rdlength != 4)
 295                         return;
 296                 dlen = 4;
 297                 break;
 298
 299         case TYPE_AAAA:
 300                 cache_service(iface, name, strlen(name), a->ttl);
 301                 if (a->rdlength != 16)
 302                         return;
 303                 dlen = 16;
 304                 break;
 305
 306         default:
 307                 return;
 308         }
 309
 310         r = cache_record_find(name, a->type, port, dlen, rdata);
 311         if (r) {
 312                 if (!a->ttl) {
 313                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 314                         r->time = time(0) + 1 - r->ttl;
 315                 } else {
 316                         r->ttl = a->ttl;
 317                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 318                 }
 319                 return;
 320         }
 321
 322         if (!a->ttl)
 323                 return;
 324
 325         r = calloc_a(sizeof(*r),
 326                 &name_buf, strlen(name) + 1,
 327                 &txt_ptr, tlen,
 328                 &rdata_ptr, dlen);
 329
 330         r->avl.key = r->record = strcpy(name_buf, name);
 331         r->type = a->type;
 332         r->ttl = a->ttl;
 333         r->port = port;
 334         r->rdlength = dlen;
 335         r->time = time(NULL);
 336         r->iface = iface;
 337
 338         if (tlen)
 339                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 340
 341         if (dlen)
 342                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 343
 344         if (avl_insert(&records, &r->avl))
 345                 free(r);
 346         else
 347                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 348 }
 349
 350 void
 351 cache_dump_records(struct blob_buf *buf, const char *name)
 352 {
 353         struct cache_record *r, *last, *next;
 354         const char *txt;
 355         char buffer[INET6_ADDRSTRLEN];
 356
 357         last = avl_last_element(&records, last, avl);
 358         for (r = avl_find_element(&records, name, r, avl); r; r = next) {
 359                 switch (r->type) {
 360                 case TYPE_TXT:
 361                         if (r->txt && strlen(r->txt)) {
 362                                 txt = r->txt;
 363                                 do {
 364                                         blobmsg_add_string(buf, "txt", txt);
 365                                         txt = &txt[strlen(txt) + 1];
 366                                 } while (*txt);
 367                         }
 368                         break;
 369
 370                 case TYPE_SRV:
 371                         if (r->port)
 372                                 blobmsg_add_u32(buf, "port", r->port);
 373                         break;
 374
 375                 case TYPE_A:
 376                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 377                                 blobmsg_add_string(buf, "ipv4", buffer);
 378                         break;
 379
 380                 case TYPE_AAAA:
 381                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 382                                 blobmsg_add_string(buf, "ipv6", buffer);
 383                         break;
 384                 }
 385
 386                 if (r == last)
 387                         break;
 388
 389                 next = avl_next_element(r, avl);
 390                 if (strcmp(r->record, next->record) != 0)
 391                         break;
 392         }
 393 }