ircd/dns.c

   1 /*
   2  *  dns.c: An interface to the resolver module in authd
   3  *  (based somewhat on ircd-ratbox dns.c)
   4  *
   5  *  Copyright (C) 2005 Aaron Sethman <androsyn@ratbox.org>
   6  *  Copyright (C) 2005-2012 ircd-ratbox development team
   7  *  Copyright (C) 2016 William Pitcock <nenolod@dereferenced.org>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or
  12  *  (at your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to the Free Software
  21  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
  22  *  USA
  23  */
  24
  25 #include "stdinc.h"
  26 #include "rb_lib.h"
  27 #include "client.h"
  28 #include "ircd_defs.h"
  29 #include "parse.h"
  30 #include "dns.h"
  31 #include "match.h"
  32 #include "logger.h"
  33 #include "s_conf.h"
  34 #include "client.h"
  35 #include "send.h"
  36 #include "numeric.h"
  37 #include "msg.h"
  38 #include "hash.h"
  39
  40 #define DNS_IDTABLE_SIZE 0x2000
  41 #define DNS_STATTABLE_SIZE 0x10
  42
  43 #define DNS_HOST_IPV4           ((char)'4')
  44 #define DNS_HOST_IPV6           ((char)'6')
  45 #define DNS_REVERSE_IPV4        ((char)'R')
  46 #define DNS_REVERSE_IPV6        ((char)'S')
  47
  48 static void submit_dns(uint16_t uid, char type, const char *addr);
  49 static void submit_dns_stat(uint16_t uid);
  50
  51 struct dnsreq
  52 {
  53         DNSCB callback;
  54         void *data;
  55 };
  56
  57 struct dnsstatreq
  58 {
  59         DNSLISTCB callback;
  60         void *data;
  61 };
  62
  63 static struct dnsreq querytable[DNS_IDTABLE_SIZE];
  64 static struct dnsstatreq stattable[DNS_STATTABLE_SIZE];
  65 rb_dlink_list nameservers;
  66
  67
  68 static uint16_t
  69 assign_dns_id(void)
  70 {
  71         static uint16_t id = 1;
  72         int loopcnt = 0;
  73         while(1)
  74         {
  75                 if(++loopcnt > DNS_IDTABLE_SIZE)
  76                         return 0;
  77                 if(id < DNS_IDTABLE_SIZE - 1 || id == 0)
  78                         id++;
  79                 else
  80                         id = 1;
  81                 if(querytable[id].callback == NULL)
  82                         break;
  83         }
  84         return (id);
  85 }
  86
  87 static uint8_t
  88 assign_dns_stat_id(void)
  89 {
  90         static uint8_t id = 1;
  91         int loopcnt = 0;
  92         while(1)
  93         {
  94                 if(++loopcnt > DNS_STATTABLE_SIZE)
  95                         return 0;
  96                 if(id < DNS_STATTABLE_SIZE - 1 || id == 0)
  97                         id++;
  98                 else
  99                         id = 1;
 100                 if(stattable[id].callback == NULL)
 101                         break;
 102         }
 103         return (id);
 104 }
 105
 106 static void
 107 handle_dns_failure(uint16_t xid)
 108 {
 109         struct dnsreq *req;
 110
 111         req = &querytable[xid];
 112         if(req->callback == NULL)
 113                 return;
 114
 115         req->callback("FAILED", 0, 0, req->data);
 116         req->callback = NULL;
 117         req->data = NULL;
 118 }
 119
 120 static void
 121 handle_dns_stat_failure(uint8_t xid)
 122 {
 123         struct dnsstatreq *req;
 124         const char *err[] = { "Unknown failure" };
 125
 126         req = &stattable[xid];
 127         if(req->callback == NULL)
 128                 return;
 129
 130         req->callback(1, err, 2, req->data);
 131
 132         req->callback = NULL;
 133         req->data = NULL;
 134 }
 135
 136 void
 137 cancel_lookup(uint16_t xid)
 138 {
 139         querytable[xid].callback = NULL;
 140         querytable[xid].data = NULL;
 141 }
 142
 143 void
 144 cancel_dns_stats(uint16_t xid)
 145 {
 146         stattable[xid].callback = NULL;
 147         stattable[xid].data = NULL;
 148 }
 149
 150 uint16_t
 151 lookup_hostname(const char *hostname, int aftype, DNSCB callback, void *data)
 152 {
 153         struct dnsreq *req;
 154         int aft;
 155         uint16_t nid;
 156         check_authd();
 157         nid = assign_dns_id();
 158         if((nid = assign_dns_id()) == 0)
 159                 return 0;
 160
 161         req = &querytable[nid];
 162
 163         req->callback = callback;
 164         req->data = data;
 165
 166 #ifdef RB_IPV6
 167         if(aftype == AF_INET6)
 168                 aft = 6;
 169         else
 170 #endif
 171                 aft = 4;
 172
 173         submit_dns(nid, aft == 4 ? DNS_HOST_IPV4 : DNS_HOST_IPV6, hostname);
 174         return (nid);
 175 }
 176
 177 uint16_t
 178 lookup_ip(const char *addr, int aftype, DNSCB callback, void *data)
 179 {
 180         struct dnsreq *req;
 181         int aft;
 182         uint16_t nid;
 183         check_authd();
 184
 185         if((nid = assign_dns_id()) == 0)
 186                 return 0;
 187
 188         req = &querytable[nid];
 189
 190         req->callback = callback;
 191         req->data = data;
 192
 193 #ifdef RB_IPV6
 194         if(aftype == AF_INET6)
 195                 aft = 6;
 196         else
 197 #endif
 198                 aft = 4;
 199
 200         submit_dns(nid, aft == 4 ? DNS_REVERSE_IPV4 : DNS_REVERSE_IPV6, addr);
 201         return (nid);
 202 }
 203
 204 uint8_t
 205 get_nameservers(DNSLISTCB callback, void *data)
 206 {
 207         struct dnsstatreq *req;
 208         uint8_t nid;
 209         check_authd();
 210
 211         if((nid = assign_dns_stat_id()) == 0)
 212                 return 0;
 213
 214         req = &stattable[nid];
 215         req->callback = callback;
 216         req->data = data;
 217
 218         submit_dns_stat(nid);
 219         return (nid);
 220 }
 221
 222 void
 223 dns_results_callback(const char *callid, const char *status, const char *type, const char *results)
 224 {
 225         struct dnsreq *req;
 226         uint16_t nid;
 227         int st;
 228         int aft;
 229         long lnid = strtol(callid, NULL, 16);
 230
 231         if(lnid > DNS_IDTABLE_SIZE || lnid == 0)
 232                 return;
 233         nid = (uint16_t)lnid;
 234         req = &querytable[nid];
 235         st = (*status == 'O');
 236         aft = *type == '6' || *type == 'S' ? 6 : 4;
 237         if(req->callback == NULL)
 238         {
 239                 /* got cancelled..oh well */
 240                 req->data = NULL;
 241                 return;
 242         }
 243 #ifdef RB_IPV6
 244         if(aft == 6)
 245                 aft = AF_INET6;
 246         else
 247 #endif
 248                 aft = AF_INET;
 249
 250         req->callback(results, st, aft, req->data);
 251         req->callback = NULL;
 252         req->data = NULL;
 253 }
 254
 255 void
 256 dns_stats_results_callback(const char *callid, const char *status, int resc, const char *resv[])
 257 {
 258         struct dnsstatreq *req;
 259         uint8_t nid;
 260         int st, i;
 261         long lnid = strtol(callid, NULL, 16);
 262
 263         if(lnid > DNS_STATTABLE_SIZE || lnid == 0)
 264                 return;
 265         nid = (uint8_t)lnid;
 266         req = &stattable[nid];
 267
 268         if(req->callback == NULL)
 269         {
 270                 req->data = NULL;
 271                 return;
 272         }
 273
 274         switch(*status)
 275         {
 276         case 'Y':
 277                 st = 0;
 278                 break;
 279         case 'X':
 280                 /* Error */
 281                 st = 1;
 282                 break;
 283         default:
 284                 /* Shouldn't happen... */
 285                 return;
 286         }
 287
 288         /* Query complete */
 289         req->callback(resc, resv, st, stattable[nid].data);
 290
 291         req->data = NULL;
 292         req->callback = NULL;
 293 }
 294
 295 static void
 296 get_nameservers_cb(int resc, const char *resv[], int status, void *data)
 297 {
 298         if(status == 0)
 299         {
 300                 rb_dlink_node *n, *tn;
 301
 302                 RB_DLINK_FOREACH_SAFE(n, tn, nameservers.head)
 303                 {
 304                         /* Clean up old nameservers */
 305                         rb_free(n->data);
 306                         rb_dlinkDestroy(n, &nameservers);
 307                 }
 308
 309                 for(int i = 0; i < resc; i++)
 310                         rb_dlinkAddAlloc(rb_strdup(resv[i]), &nameservers);
 311         }
 312         else
 313         {
 314                 const char *error = resc ? resv[resc] : "Unknown error";
 315                 iwarn(L_MAIN, "Error getting DNS servers: %s", error);
 316         }
 317 }
 318
 319 void
 320 init_nameserver_cache(void)
 321 {
 322         (void)get_nameservers(get_nameservers_cb, NULL);
 323 }
 324
 325 static void
 326 submit_dns(uint16_t nid, char type, const char *addr)
 327 {
 328         if(authd_helper == NULL)
 329         {
 330                 handle_dns_failure(nid);
 331                 return;
 332         }
 333         rb_helper_write(authd_helper, "D %x %c %s", nid, type, addr);
 334 }
 335
 336 static void
 337 submit_dns_stat(uint16_t nid)
 338 {
 339         if(authd_helper == NULL)
 340         {
 341                 handle_dns_stat_failure(nid);
 342                 return;
 343         }
 344         rb_helper_write(authd_helper, "S %x D", nid);
 345 }