ircd/m_nick.c

   1 /*
   2  * IRC - Internet Relay Chat, ircd/m_nick.c
   3  * Copyright (C) 1990 Jarkko Oikarinen and
   4  *                    University of Oulu, Computing Center
   5  *
   6  * See file AUTHORS in IRC package for additional names of
   7  * the programmers.
   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 1, or (at your option)
  12  * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  *
  23  * $Id: m_nick.c,v 1.25 2005/03/19 23:22:09 entrope Exp $
  24  */
  25
  26 /*
  27  * m_functions execute protocol messages on this server:
  28  *
  29  *    cptr    is always NON-NULL, pointing to a *LOCAL* client
  30  *            structure (with an open socket connected!). This
  31  *            identifies the physical socket where the message
  32  *            originated (or which caused the m_function to be
  33  *            executed--some m_functions may call others...).
  34  *
  35  *    sptr    is the source of the message, defined by the
  36  *            prefix part of the message if present. If not
  37  *            or prefix not found, then sptr==cptr.
  38  *
  39  *            (!IsServer(cptr)) => (cptr == sptr), because
  40  *            prefixes are taken *only* from servers...
  41  *
  42  *            (IsServer(cptr))
  43  *                    (sptr == cptr) => the message didn't
  44  *                    have the prefix.
  45  *
  46  *                    (sptr != cptr && IsServer(sptr) means
  47  *                    the prefix specified servername. (?)
  48  *
  49  *                    (sptr != cptr && !IsServer(sptr) means
  50  *                    that message originated from a remote
  51  *                    user (not local).
  52  *
  53  *            combining
  54  *
  55  *            (!IsServer(sptr)) means that, sptr can safely
  56  *            taken as defining the target structure of the
  57  *            message in this server.
  58  *
  59  *    *Always* true (if 'parse' and others are working correct):
  60  *
  61  *    1)      sptr->from == cptr  (note: cptr->from == cptr)
  62  *
  63  *    2)      MyConnect(sptr) <=> sptr == cptr (e.g. sptr
  64  *            *cannot* be a local connection, unless it's
  65  *            actually cptr!). [MyConnect(x) should probably
  66  *            be defined as (x == x->from) --msa ]
  67  *
  68  *    parc    number of variable parameter strings (if zero,
  69  *            parv is allowed to be NULL)
  70  *
  71  *    parv    a NULL terminated list of parameter pointers,
  72  *
  73  *                    parv[0], sender (prefix string), if not present
  74  *                            this points to an empty string.
  75  *                    parv[1]...parv[parc-1]
  76  *                            pointers to additional parameters
  77  *                    parv[parc] == NULL, *always*
  78  *
  79  *            note:   it is guaranteed that parv[0]..parv[parc-1] are all
  80  *                    non-NULL pointers.
  81  */
  82 #include "config.h"
  83
  84 #include "IPcheck.h"
  85 #include "client.h"
  86 #include "hash.h"
  87 #include "ircd.h"
  88 #include "ircd_chattr.h"
  89 #include "ircd_features.h"
  90 #include "ircd_log.h"
  91 #include "ircd_reply.h"
  92 #include "ircd_string.h"
  93 #include "msg.h"
  94 #include "numeric.h"
  95 #include "numnicks.h"
  96 #include "s_debug.h"
  97 #include "s_misc.h"
  98 #include "s_user.h"
  99 #include "send.h"
 100 #include "sys.h"
 101
 102 /* #include <assert.h> -- Now using assert in ircd_log.h */
 103 #include <stdlib.h>
 104 #include <string.h>
 105
 106  /*
 107 * 'do_nick_name' ensures that the given parameter (nick) is really a proper
 108 * string for a nickname (note, the 'nick' may be modified in the process...)
 109 *
 110 * RETURNS the length of the final NICKNAME (0, if nickname is invalid)
 111 *
 112 * Nickname characters are in range 'A'..'}', '_', '-', '0'..'9'
 113 *  anything outside the above set will terminate nickname.
 114 * In addition, the first character cannot be '-' or a Digit.
 115 *
 116 * Note:
 117 *  The '~'-character should be allowed, but a change should be global,
 118 *  some confusion would result if only few servers allowed it...
 119 */
 120 static int do_nick_name(char* nick)
 121 {
 122   char* ch  = nick;
 123   char* end = ch + NICKLEN;
 124   assert(0 != ch);
 125
 126   /* first character in [0..9-] */
 127   if (*ch == '-' || IsDigit(*ch))
 128     return 0;
 129   for ( ; (ch < end) && *ch; ++ch)
 130     if (!IsNickChar(*ch))
 131       break;
 132
 133   *ch = '\0';
 134
 135   return (ch - nick);
 136 }
 137
 138 /*
 139  * m_nick - message handler for local clients
 140  * parv[0] = sender prefix
 141  * parv[1] = nickname
 142  */
 143 int m_nick(struct Client* cptr, struct Client* sptr, int parc, char* parv[])
 144 {
 145   struct Client* acptr;
 146   char           nick[NICKLEN + 2];
 147   char*          arg;
 148   char*          s;
 149   const char*    client_name;
 150
 151   assert(0 != cptr);
 152   assert(cptr == sptr);
 153
 154   /*
 155    * parv[0] will be empty for clients connecting for the first time
 156    */
 157   client_name = (*(cli_name(sptr))) ? cli_name(sptr) : "*";
 158
 159   if (parc < 2) {
 160     send_reply(sptr, ERR_NONICKNAMEGIVEN);
 161     return 0;
 162   }
 163   /*
 164    * Don't let them send make us send back a really long string of
 165    * garbage
 166    */
 167   arg = parv[1];
 168   if (strlen(arg) > IRCD_MIN(NICKLEN, feature_int(FEAT_NICKLEN)))
 169     arg[IRCD_MIN(NICKLEN, feature_int(FEAT_NICKLEN))] = '\0';
 170
 171   if ((s = strchr(arg, '~')))
 172     *s = '\0';
 173
 174   strcpy(nick, arg);
 175
 176   /*
 177    * If do_nick_name() returns a null name then reject it.
 178    */
 179   if (0 == do_nick_name(nick)) {
 180     send_reply(sptr, ERR_ERRONEUSNICKNAME, arg);
 181     return 0;
 182   }
 183
 184   /*
 185    * Check if this is a LOCAL user trying to use a reserved (Juped)
 186    * nick, if so tell him that it's a nick in use...
 187    */
 188   if (isNickJuped(nick)) {
 189     send_reply(sptr, ERR_NICKNAMEINUSE, nick);
 190     return 0;                        /* NICK message ignored */
 191   }
 192
 193   if (!(acptr = FindClient(nick))) {
 194     /*
 195      * No collisions, all clear...
 196      */
 197     return set_nick_name(cptr, sptr, nick, parc, parv);
 198   }
 199   if (IsServer(acptr)) {
 200     send_reply(sptr, ERR_NICKNAMEINUSE, nick);
 201     return 0;                        /* NICK message ignored */
 202   }
 203   /*
 204    * If acptr == sptr, then we have a client doing a nick
 205    * change between *equivalent* nicknames as far as server
 206    * is concerned (user is changing the case of his/her
 207    * nickname or somesuch)
 208    */
 209   if (acptr == sptr) {
 210     /*
 211      * If acptr == sptr, then we have a client doing a nick
 212      * change between *equivalent* nicknames as far as server
 213      * is concerned (user is changing the case of his/her
 214      * nickname or somesuch)
 215      */
 216     if (0 != strcmp(cli_name(acptr), nick)) {
 217       /*
 218        * Allows change of case in his/her nick
 219        */
 220       return set_nick_name(cptr, sptr, nick, parc, parv);
 221     }
 222     /*
 223      * This is just ':old NICK old' type thing.
 224      * Just forget the whole thing here. There is
 225      * no point forwarding it to anywhere,
 226      * especially since servers prior to this
 227      * version would treat it as nick collision.
 228      */
 229     return 0;
 230   }
 231   /*
 232    * Note: From this point forward it can be assumed that
 233    * acptr != sptr (point to different client structures).
 234    */
 235   assert(acptr != sptr);
 236   /*
 237    * If the older one is "non-person", the new entry is just
 238    * allowed to overwrite it. Just silently drop non-person,
 239    * and proceed with the nick. This should take care of the
 240    * "dormant nick" way of generating collisions...
 241    *
 242    * XXX - hmmm can this happen after one is registered?
 243    *
 244    * Yes, client 1 connects to IRC and registers, client 2 connects and
 245    * sends "NICK foo" but doesn't send anything more.  client 1 now does
 246    * /nick foo, they should succeed and client 2 gets disconnected with
 247    * the message below.
 248    */
 249   if (IsUnknown(acptr) && MyConnect(acptr)) {
 250     ServerStats->is_ref++;
 251     IPcheck_connect_fail(acptr);
 252     exit_client(cptr, acptr, &me, "Overridden by other sign on");
 253     return set_nick_name(cptr, sptr, nick, parc, parv);
 254   }
 255   /*
 256    * NICK is coming from local client connection. Just
 257    * send error reply and ignore the command.
 258    */
 259   send_reply(sptr, ERR_NICKNAMEINUSE, nick);
 260   return 0;                        /* NICK message ignored */
 261 }
 262
 263
 264 /*
 265  * ms_nick - server message handler for nicks
 266  * parv[0] = sender prefix
 267  * parv[1] = nickname
 268  *
 269  * If from server, source is client:
 270  *   parv[2] = timestamp
 271  *
 272  * Source is server:
 273  *   parv[2] = hopcount
 274  *   parv[3] = timestamp
 275  *   parv[4] = username
 276  *   parv[5] = hostname
 277  *   parv[6] = umode (optional)
 278  *   parv[parc-3] = IP#                 <- Only Protocol >= 10
 279  *   parv[parc-2] = YXX, numeric nick   <- Only Protocol >= 10
 280  *   parv[parc-1] = info
 281  *   parv[0] = server
 282  */
 283 int ms_nick(struct Client* cptr, struct Client* sptr, int parc, char* parv[])
 284 {
 285   struct Client *acptr;
 286   char nick[NICKLEN + 2];
 287   time_t lastnick = 0;
 288   int differ = 1;
 289   const char *type;
 290
 291   assert(0 != cptr);
 292   assert(0 != sptr);
 293   assert(IsServer(cptr));
 294
 295   if ((IsServer(sptr) && parc < 8) || parc < 3)
 296   {
 297     sendto_opmask_butone(0, SNO_OLDSNO, "bad NICK param count for %s from %C",
 298                          parv[1], cptr);
 299     return need_more_params(sptr, "NICK");
 300   }
 301
 302   ircd_strncpy(nick, parv[1], NICKLEN);
 303   nick[NICKLEN] = '\0';
 304
 305   if (IsServer(sptr))
 306   {
 307     lastnick = atoi(parv[3]);
 308     if (lastnick > OLDEST_TS && !IsBurstOrBurstAck(sptr))
 309       cli_serv(sptr)->lag = TStime() - lastnick;
 310   }
 311   else
 312   {
 313     lastnick = atoi(parv[2]);
 314     if (lastnick > OLDEST_TS && !IsBurstOrBurstAck(sptr))
 315       cli_serv(cli_user(sptr)->server)->lag = TStime() - lastnick;
 316   }
 317   /*
 318    * If do_nick_name() returns a null name OR if the server sent a nick
 319    * name and do_nick_name() changed it in some way (due to rules of nick
 320    * creation) then reject it. If from a server and we reject it,
 321    * and KILL it. -avalon 4/4/92
 322    */
 323   if (!do_nick_name(nick) || strcmp(nick, parv[1]))
 324   {
 325     send_reply(sptr, ERR_ERRONEUSNICKNAME, parv[1]);
 326
 327     ++ServerStats->is_kill;
 328     sendto_opmask_butone(0, SNO_OLDSNO, "Bad Nick: %s From: %s %C", parv[1],
 329                          parv[0], cptr);
 330     sendcmdto_one(&me, CMD_KILL, cptr, "%s :%s (%s <- %s[%s])",
 331                   IsServer(sptr) ? parv[parc - 2] : parv[0], cli_name(&me), parv[1],
 332                   nick, cli_name(cptr));
 333     if (!IsServer(sptr))
 334     {
 335       /*
 336        * bad nick _change_
 337        */
 338       sendcmdto_serv_butone(&me, CMD_KILL, 0, "%s :%s (%s <- %s!%s@%s)",
 339                             parv[0], cli_name(&me), cli_name(cptr), parv[0],
 340                             cli_user(sptr) ? cli_username(sptr) : "",
 341                             cli_user(sptr) ? cli_name(cli_user(sptr)->server) :
 342                             cli_name(cptr));
 343     }
 344     return 0;
 345   }
 346   /* Check against nick name collisions. */
 347   if ((acptr = FindClient(nick)) == NULL)
 348     /* No collisions, all clear... */
 349     return set_nick_name(cptr, sptr, nick, parc, parv);
 350
 351   /*
 352    * If acptr == sptr, then we have a client doing a nick
 353    * change between *equivalent* nicknames as far as server
 354    * is concerned (user is changing the case of his/her
 355    * nickname or somesuch)
 356    */
 357   if (acptr == sptr)
 358   {
 359     if (strcmp(cli_name(acptr), nick) != 0)
 360       /* Allows change of case in his/her nick */
 361       return set_nick_name(cptr, sptr, nick, parc, parv);
 362     else
 363       /* Setting their nick to what it already is? Ignore it. */
 364       return 0;
 365   }
 366   /* now we know we have a real collision. */
 367   /*
 368    * Note: From this point forward it can be assumed that
 369    * acptr != sptr (point to different client structures).
 370    */
 371   assert(acptr != sptr);
 372   /*
 373    * If the older one is "non-person", the new entry is just
 374    * allowed to overwrite it. Just silently drop non-person,
 375    * and proceed with the nick. This should take care of the
 376    * "dormant nick" way of generating collisions...
 377    */
 378   if (IsUnknown(acptr) && MyConnect(acptr))
 379   {
 380     ServerStats->is_ref++;
 381     IPcheck_connect_fail(acptr);
 382     exit_client(cptr, acptr, &me, "Overridden by other sign on");
 383     return set_nick_name(cptr, sptr, nick, parc, parv);
 384   }
 385   /*
 386    * Decide, we really have a nick collision and deal with it
 387    */
 388   /*
 389    * NICK was coming from a server connection.
 390    * This means we have a race condition (two users signing on
 391    * at the same time), or two net fragments reconnecting with the same nick.
 392    * The latter can happen because two different users connected
 393    * or because one and the same user switched server during a net break.
 394    * If the TimeStamps are equal, we kill both (or only 'new'
 395    * if it was a ":server NICK new ...").
 396    * Otherwise we kill the youngest when user@host differ,
 397    * or the oldest when they are the same.
 398    * We treat user and ~user as different, because if it wasn't
 399    * a faked ~user the AUTH wouldn't have added the '~'.
 400    * --Run
 401    *
 402    */
 403   if (IsServer(sptr))
 404   {
 405     struct irc_in_addr ip;
 406     /*
 407      * A new NICK being introduced by a neighbouring
 408      * server (e.g. message type ":server NICK new ..." received)
 409      *
 410      * compare IP address and username
 411      */
 412     base64toip(parv[parc - 3], &ip);
 413     differ =  (0 != memcmp(&cli_ip(acptr), &ip, sizeof(cli_ip(acptr)))) ||
 414               (0 != ircd_strcmp(cli_user(acptr)->username, parv[4]));
 415     sendto_opmask_butone(0, SNO_OLDSNO, "Nick collision on %C (%C %Tu <- "
 416                          "%C %Tu (%s user@host))", acptr, cli_from(acptr),
 417                          cli_lastnick(acptr), cptr, lastnick,
 418                          differ ? "Different" : "Same");
 419   }
 420   else
 421   {
 422     /*
 423      * A NICK change has collided (e.g. message type ":old NICK new").
 424      *
 425      * compare IP address and username
 426      */
 427     differ =  (0 != memcmp(&cli_ip(acptr), &cli_ip(sptr), sizeof(cli_ip(acptr)))) ||
 428               (0 != ircd_strcmp(cli_user(acptr)->username, cli_user(sptr)->username));
 429     sendto_opmask_butone(0, SNO_OLDSNO, "Nick change collision from %C to "
 430                          "%C (%C %Tu <- %C %Tu)", sptr, acptr, cli_from(acptr),
 431                          cli_lastnick(acptr), cptr, lastnick);
 432   }
 433   type = differ ? "older nick overruled" : "nick collision from same user@host";
 434   /*
 435    * Now remove (kill) the nick on our side if it is the youngest.
 436    * If no timestamp was received, we ignore the incoming nick
 437    * (and expect a KILL for our legit nick soon ):
 438    * When the timestamps are equal we kill both nicks. --Run
 439    * acptr->from != cptr should *always* be true (?).
 440    *
 441    * This exits the client sending the NICK message
 442    */
 443   if ((differ && lastnick >= cli_lastnick(acptr)) ||
 444       (!differ && lastnick <= cli_lastnick(acptr)))
 445   {
 446     /* We need to bounce this kill straight back... Although the nick message
 447      * for acptr is probably waiting in their recvq from me, its also possible
 448      * that sptr will change their nick on cptr before cptr receives the
 449      * nick message for acptr, which would leave acptr and sptr both alive
 450      * on cptr, but only acptr alive on me, i.e. desync. This extra kill
 451      * message has been absent for a while in ircu although it was a major
 452      * problem when it was tried on efnet, so I don't know how big an issue it
 453      * is. Probably best that this be left here, anyway...
 454      */
 455     ServerStats->is_kill++;
 456     sendcmdto_one(&me, CMD_KILL, cptr, "%s :%s (%s)",
 457                   nick, cli_name(&me), type);
 458     /* But if this was a nick change and not a nick introduction,
 459      * we also need to ensure that we remove our local state
 460      * record of the original client... Also, the rest of the
 461      * net should be informed...
 462      */
 463     if (!IsServer(sptr))
 464     {
 465       assert(!MyConnect(sptr));
 466       /* Inform the rest of the net... */
 467       sendcmdto_serv_butone(&me, CMD_KILL, cptr, "%s :%s (%s)",
 468                             nick, cli_name(&me), type);
 469       /* Don't go sending off a QUIT message... */
 470       SetFlag(sptr, FLAG_KILLED);
 471       /* Remove them locally. */
 472       exit_client_msg(cptr, sptr, &me,
 473                       "Killed (%s (%s))",
 474                       feature_str(FEAT_HIS_SERVERNAME), type);
 475       /*
 476        * We have killed sptr off, zero out it's pointer so if it's used
 477        * again we'll know about it --Bleep
 478        */
 479       sptr = NULL;
 480     }
 481     /* If the timestamps differ and we just killed sptr, we don't need to kill
 482      * acptr as well.
 483      */
 484     if (lastnick != cli_lastnick(acptr))
 485       return 0;
 486   }
 487   /* Tell acptr why we are killing it. */
 488   send_reply(acptr, ERR_NICKCOLLISION, nick);
 489
 490   ServerStats->is_kill++;
 491   SetFlag(acptr, FLAG_KILLED);
 492   /*
 493    * This exits the client we had before getting the NICK message
 494    */
 495   sendcmdto_serv_butone(&me, CMD_KILL, NULL, "%C :%s"
 496                         " (%s)", acptr, feature_str(FEAT_HIS_SERVERNAME),
 497                         type);
 498   exit_client_msg(cptr, acptr, &me, "Killed (%s (%s))",
 499                   feature_str(FEAT_HIS_SERVERNAME), type);
 500   if (lastnick == cli_lastnick(acptr))
 501     return 0;
 502   if (sptr == NULL)
 503     return 0;
 504   return set_nick_name(cptr, sptr, nick, parc, parv);
 505 }