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 <asm/byteorder.h>
  28 #include <arpa/nameser.h>
  29 #include <resolv.h>
  30 #include <time.h>
  31
  32 #include <libubox/usock.h>
  33 #include <libubox/uloop.h>
  34 #include <libubox/avl-cmp.h>
  35 #include <libubox/blobmsg_json.h>
  36 #include <libubox/kvlist.h>
  37 #include <libubus.h>
  38
  39 #include "cache.h"
  40 #include "util.h"
  41 #include "dns.h"
  42 #include "interface.h"
  43
  44 static struct uloop_timeout cache_gc;
  45 struct avl_tree entries;
  46 static AVL_TREE(records, avl_strcmp, true, NULL);
  47
  48 static void
  49 cache_record_free(struct cache_record *r)
  50 {
  51         DBG(2, "%s %s\n", dns_type_string(r->type), r->record);
  52         avl_delete(&records, &r->avl);
  53         free(r);
  54 }
  55
  56 static void
  57 cache_entry_free(struct cache_entry *s)
  58 {
  59         DBG(2, "%s\n", s->entry);
  60         avl_delete(&entries, &s->avl);
  61         free(s);
  62 }
  63
  64 static int
  65 cache_is_expired(time_t t, uint32_t ttl)
  66 {
  67         if (time(NULL) - t >= ttl)
  68                 return 1;
  69
  70         return 0;
  71 }
  72
  73 static void
  74 cache_gc_timer(struct uloop_timeout *timeout)
  75 {
  76         struct cache_record *r, *p;
  77         struct cache_entry *s, *t;
  78
  79         avl_for_each_element_safe(&records, r, avl, p)
  80                 if (cache_is_expired(r->time, r->ttl))
  81                         cache_record_free(r);
  82
  83         avl_for_each_element_safe(&entries, s, avl, t) {
  84                 if (!s->host)
  85                         continue;
  86                 if (cache_is_expired(s->time, s->ttl))
  87                         cache_entry_free(s);
  88         }
  89
  90         uloop_timeout_set(timeout, 10000);
  91 }
  92
  93 int
  94 cache_init(void)
  95 {
  96         avl_init(&entries, avl_strcmp, true, NULL);
  97
  98         cache_gc.cb = cache_gc_timer;
  99         uloop_timeout_set(&cache_gc, 10000);
 100
 101         return 0;
 102 }
 103
 104 void cache_cleanup(void)
 105 {
 106         struct cache_record *r, *p;
 107         struct cache_entry *s, *t;
 108
 109         avl_for_each_element_safe(&records, r, avl, p)
 110                 cache_record_free(r);
 111
 112         avl_for_each_element_safe(&entries, s, avl, t)
 113                 cache_entry_free(s);
 114 }
 115
 116 void
 117 cache_scan(void)
 118 {
 119         struct interface *iface;
 120         struct cache_entry *s;
 121
 122         vlist_for_each_element(&interfaces, iface, node)
 123                 avl_for_each_element(&entries, s, avl)
 124                         dns_send_question(iface, s->entry, TYPE_PTR);
 125 }
 126
 127 static struct cache_entry*
 128 cache_entry(struct interface *iface, char *entry, int hlen, int ttl)
 129 {
 130         struct cache_entry *s;
 131         char *entry_buf;
 132         char *host_buf;
 133         char *type;
 134
 135         s = avl_find_element(&entries, entry, s, avl);
 136         if (s)
 137                 return s;
 138
 139         s = calloc_a(sizeof(*s),
 140                 &entry_buf, strlen(entry) + 1,
 141                 &host_buf, hlen ? hlen + 1 : 0);
 142
 143         s->avl.key = s->entry = strcpy(entry_buf, entry);
 144         s->time = time(NULL);
 145         s->ttl = ttl;
 146
 147         if (hlen)
 148                 s->host = strncpy(host_buf, s->entry, hlen);
 149
 150         type = strstr(entry_buf, "._");
 151         if (type)
 152                 type++;
 153         if (type)
 154                 s->avl.key = type;
 155         avl_insert(&entries, &s->avl);
 156
 157         if (!hlen)
 158                 dns_send_question(iface, entry, TYPE_PTR);
 159
 160         return s;
 161 }
 162
 163 static struct cache_record*
 164 cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata)
 165 {
 166         struct cache_record *l = avl_find_element(&records, record, l, avl);
 167
 168         if (!l)
 169                 return NULL;
 170
 171         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 172                 struct cache_record *r = l;
 173
 174                 l = avl_next_element(l, avl);
 175                 if (r->type != type)
 176                         continue;
 177
 178                 if (r->type == TYPE_TXT || (r->type == TYPE_SRV))
 179                         return r;
 180
 181                 if (r->port != port)
 182                         continue;
 183
 184                 if (r->rdlength != rdlength)
 185                         continue;
 186
 187                 if (!!r->rdata != !!rdata)
 188                         continue;
 189
 190                 if (!r->rdata || !rdata || memcmp(r->rdata, rdata, rdlength))
 191                         continue;
 192
 193                 return r;
 194         }
 195
 196         return NULL;
 197 }
 198
 199 int
 200 cache_host_is_known(char *record)
 201 {
 202         struct cache_record *l = avl_find_element(&records, record, l, avl);
 203
 204         if (!l)
 205                 return 0;
 206
 207         while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
 208                 struct cache_record *r = l;
 209
 210                 l = avl_next_element(l, avl);
 211                 if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 212                         continue;
 213                 return 1;
 214         }
 215
 216         return 0;
 217 }
 218
 219 void
 220 cache_answer(struct interface *iface, uint8_t *base, int blen, char *name, struct dns_answer *a, uint8_t *rdata)
 221 {
 222         struct dns_srv_data *dsd = (struct dns_srv_data *) rdata;
 223         struct cache_record *r;
 224         int port = 0, dlen = 0, tlen = 0, nlen, rdlength;
 225         char *p = NULL;
 226         char *name_buf;
 227         void *rdata_ptr, *txt_ptr;
 228         int host_len = 0;
 229         static char *rdata_buffer = (char *) mdns_buf;
 230
 231         if (!(a->class & CLASS_IN))
 232                 return;
 233
 234         nlen = strlen(name);
 235
 236         switch (a->type) {
 237         case TYPE_PTR:
 238                 if (a->rdlength < 2)
 239                         return;
 240
 241                 if (dn_expand(base, base + blen, rdata, rdata_buffer, MAX_DATA_LEN) < 0) {
 242                         perror("process_answer/dn_expand");
 243                         return;
 244                 }
 245
 246                 DBG(1, "A -> %s %s %s\n", dns_type_string(a->type), name, rdata_buffer);
 247
 248                 rdlength = strlen(rdata_buffer);
 249
 250                 if (strcmp(C_DNS_SD, name) != 0 &&
 251                     nlen + 1 < rdlength && !strcmp(rdata_buffer + rdlength - nlen, name))
 252                         host_len = rdlength - nlen - 1;
 253
 254                 cache_entry(iface, rdata_buffer, host_len, a->ttl);
 255                 return;
 256
 257         case TYPE_SRV:
 258                 if (a->rdlength < 8)
 259                         return;
 260
 261                 port = be16_to_cpu(dsd->port);
 262                 break;
 263
 264         case TYPE_TXT:
 265                 rdlength = a->rdlength;
 266                 if (rdlength <= 2)
 267                         return;
 268
 269                 memcpy(rdata_buffer, &rdata[1], rdlength);
 270                 rdata_buffer[rdlength] = rdata_buffer[rdlength + 1] = '\0';
 271                 tlen = rdlength + 1;
 272                 p = &rdata_buffer[*rdata];
 273
 274                 do {
 275                         uint8_t v = *p;
 276
 277                         *p = '\0';
 278                         if (v)
 279                                 p += v + 1;
 280                 } while (*p);
 281                 break;
 282
 283         case TYPE_A:
 284                 cache_entry(iface, name, strlen(name), a->ttl);
 285                 if (a->rdlength != 4)
 286                         return;
 287                 dlen = 4;
 288                 break;
 289
 290         case TYPE_AAAA:
 291                 cache_entry(iface, name, strlen(name), a->ttl);
 292                 if (a->rdlength != 16)
 293                         return;
 294                 dlen = 16;
 295                 break;
 296
 297         default:
 298                 return;
 299         }
 300
 301         r = cache_record_find(name, a->type, port, dlen, rdata);
 302         if (r) {
 303                 if (!a->ttl) {
 304                         cache_record_free(r);
 305                         DBG(1, "D -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 306                 } else {
 307                         r->ttl = a->ttl;
 308                         DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 309                 }
 310                 return;
 311         }
 312
 313         if (!a->ttl)
 314                 return;
 315
 316         r = calloc_a(sizeof(*r),
 317                 &name_buf, strlen(name) + 1,
 318                 &txt_ptr, tlen,
 319                 &rdata_ptr, dlen);
 320
 321         r->avl.key = r->record = strcpy(name_buf, name);
 322         r->type = a->type;
 323         r->ttl = a->ttl;
 324         r->port = port;
 325         r->rdlength = dlen;
 326         r->time = time(NULL);
 327
 328         if (tlen)
 329                 r->txt = memcpy(txt_ptr, rdata_buffer, tlen);
 330
 331         if (dlen)
 332                 r->rdata = memcpy(rdata_ptr, rdata, dlen);
 333
 334         if (avl_insert(&records, &r->avl))
 335                 free(r);
 336         else
 337                 DBG(1, "A -> %s %s ttl:%d\n", dns_type_string(r->type), r->record, r->ttl);
 338 }
 339
 340 void
 341 cache_dump_records(struct blob_buf *buf, const char *name)
 342 {
 343         struct cache_record *r, *q = avl_find_element(&records, name, r, avl);
 344         const char *txt;
 345         char buffer[INET6_ADDRSTRLEN];
 346
 347         if (!q)
 348                 return;
 349
 350         do {
 351                 r = q;
 352                 switch (r->type) {
 353                 case TYPE_TXT:
 354                         if (r->txt && strlen(r->txt)) {
 355                                 txt = r->txt;
 356                                 do {
 357                                         blobmsg_add_string(buf, "txt", txt);
 358                                         txt = &txt[strlen(txt) + 1];
 359                                 } while (*txt);
 360                         }
 361                         break;
 362
 363                 case TYPE_SRV:
 364                         if (r->port)
 365                                 blobmsg_add_u32(buf, "port", r->port);
 366                         break;
 367
 368                 case TYPE_A:
 369                         if ((r->rdlength == 4) && inet_ntop(AF_INET, r->rdata, buffer, INET6_ADDRSTRLEN))
 370                                 blobmsg_add_string(buf, "ipv4", buffer);
 371                         break;
 372
 373                 case TYPE_AAAA:
 374                         if ((r->rdlength == 16) && inet_ntop(AF_INET6, r->rdata, buffer, INET6_ADDRSTRLEN))
 375                                 blobmsg_add_string(buf, "ipv6", buffer);
 376                         break;
 377                 }
 378                 q = avl_next_element(r, avl);
 379         } while (q && !strcmp(r->record, q->record));
 380 }