예제 #1
0
파일: client.c 프로젝트: kazcw/pande
/**
 * Introduce a new user or service client in the network.
 *
 * @param From Remote server introducing the client or NULL (local).
 * @param Client New client.
 * @param Type Type of the client (CLIENT_USER or CLIENT_SERVICE).
 */
GLOBAL void
Client_Introduce(CLIENT *From, CLIENT *Client, int Type)
{
	/* Set client type (user or service) */
	Client_SetType(Client, Type);

	if (From) {
		if (Conf_NickIsService(Conf_GetServer(Client_Conn(From)),
				   Client_ID(Client)))
			Client_SetType(Client, CLIENT_SERVICE);
		LogDebug("%s \"%s\" (+%s) registered (via %s, on %s, %d hop%s).",
			 Client_TypeText(Client), Client_Mask(Client),
			 Client_Modes(Client), Client_ID(From),
			 Client_ID(Client_Introducer(Client)),
			 Client_Hops(Client), Client_Hops(Client) > 1 ? "s": "");
	} else {
		Log(LOG_NOTICE, "%s \"%s\" registered (connection %d).",
		    Client_TypeText(Client), Client_Mask(Client),
		    Client_Conn(Client));
		Log_ServerNotice('c', "Client connecting: %s (%s@%s) [%s] - %s",
			         Client_ID(Client), Client_User(Client),
				 Client_Hostname(Client),
				 Conn_IPA(Client_Conn(Client)),
				 Client_TypeText(Client));
	}

	/* Inform other servers */
	IRC_WriteStrServersPrefixFlag_CB(From,
				From != NULL ? From : Client_ThisServer(),
				'\0', cb_introduceClient, (void *)Client);
} /* Client_Introduce */
예제 #2
0
파일: login.c 프로젝트: LucentW/ngircd
/**
 * Initiate client login.
 *
 * This function is called after the daemon received the required NICK and
 * USER commands of a new client. If the daemon is compiled with support for
 * PAM, the authentication sub-processs is forked; otherwise the global server
 * password is checked.
 *
 * @param Client The client logging in.
 * @returns CONNECTED or DISCONNECTED.
 */
GLOBAL bool
Login_User(CLIENT * Client)
{
#ifdef PAM
	int pipefd[2], result;
	pid_t pid;
#endif
	CONN_ID conn;

	assert(Client != NULL);
	conn = Client_Conn(Client);

#ifndef STRICT_RFC
	if (Conf_AuthPing) {
		/* Did we receive the "auth PONG" already? */
		if (Conn_GetAuthPing(conn)) {
			Client_SetType(Client, CLIENT_WAITAUTHPING);
			LogDebug("Connection %d: Waiting for AUTH PONG ...", conn);
			return CONNECTED;
		}
	}
#endif

	/* Still waiting for "CAP END" command? */
	if (Client_Cap(Client) & CLIENT_CAP_PENDING) {
		Client_SetType(Client, CLIENT_WAITCAPEND);
		LogDebug("Connection %d: Waiting for CAP END ...", conn);
		return CONNECTED;
	}

#ifdef PAM
	if (!Conf_PAM) {
		/* Don't do any PAM authentication at all if PAM is not
		 * enabled, instead emulate the behavior of the daemon
		 * compiled without PAM support. */
		if (strcmp(Conn_Password(conn), Conf_ServerPwd) == 0)
			return Login_User_PostAuth(Client);
		Client_Reject(Client, "Bad server password", false);
		return DISCONNECTED;
	}

	if (Conf_PAMIsOptional &&
	    strcmp(Conn_Password(conn), "") == 0) {
		/* Clients are not required to send a password and to be PAM-
		 * authenticated at all. If not, they won't become "identified"
		 * and keep the "~" in their supplied user name.
		 * Therefore it is sensible to either set Conf_PAMisOptional or
		 * to enable IDENT lookups -- not both. */
		return Login_User_PostAuth(Client);
	}

	if (Conf_PAM) {
		/* Fork child process for PAM authentication; and make sure that the
		 * process timeout is set higher than the login timeout! */
		pid = Proc_Fork(Conn_GetProcStat(conn), pipefd,
				cb_Read_Auth_Result, Conf_PongTimeout + 1);
		if (pid > 0) {
			LogDebug("Authenticator for connection %d created (PID %d).",
				 conn, pid);
			return CONNECTED;
		} else {
			/* Sub process */
			Log_Init_Subprocess("Auth");
			Conn_CloseAllSockets(NONE);
			result = PAM_Authenticate(Client);
			if (write(pipefd[1], &result, sizeof(result)) != sizeof(result))
				Log_Subprocess(LOG_ERR,
					       "Failed to pipe result to parent!");
			Log_Exit_Subprocess("Auth");
			exit(0);
		}
	} else return CONNECTED;
#else
	/* Check global server password ... */
	if (strcmp(Conn_Password(conn), Conf_ServerPwd) != 0) {
		/* Bad password! */
		Client_Reject(Client, "Bad server password", false);
		return DISCONNECTED;
	}
	return Login_User_PostAuth(Client);
#endif
}
예제 #3
0
파일: numeric.c 프로젝트: LucentW/ngircd
/**
 * Handle ENDOFMOTD (376) numeric and login remote server.
 * The peer is either an IRC server (no IRC+ protocol), or we got the
 * ENDOFMOTD numeric from an IRC+ server. We have to register the new server.
 */
GLOBAL bool
IRC_Num_ENDOFMOTD(CLIENT * Client, UNUSED REQUEST * Req)
{
	int max_hops, i;
	CLIENT *c;
	CHANNEL *chan;

	Client_SetType(Client, CLIENT_SERVER);

	Log(LOG_NOTICE | LOG_snotice,
	    "Server \"%s\" registered (connection %d, 1 hop - direct link).",
	    Client_ID(Client), Client_Conn(Client));

	/* Get highest hop count */
	max_hops = 0;
	c = Client_First();
	while (c) {
		if (Client_Hops(c) > max_hops)
			max_hops = Client_Hops(c);
		c = Client_Next(c);
	}

	/* Inform the new server about all other servers, and announce the
	 * new server to all the already registered ones. Important: we have
	 * to do this "in order" and can't introduce servers of which the
	 * "toplevel server" isn't known already. */
	for (i = 0; i < (max_hops + 1); i++) {
		for (c = Client_First(); c != NULL; c = Client_Next(c)) {
			if (Client_Type(c) != CLIENT_SERVER)
				continue;	/* not a server */
			if (Client_Hops(c) != i)
				continue;	/* not actual "nesting level" */
			if (c == Client || c == Client_ThisServer())
				continue;	/* that's us or the peer! */

			if (!Announce_Server(Client, c))
				return DISCONNECTED;
		}
	}

	/* Announce all the users to the new server */
	c = Client_First();
	while (c) {
		if (Client_Type(c) == CLIENT_USER ||
		    Client_Type(c) == CLIENT_SERVICE) {
			if (!Client_Announce(Client, Client_ThisServer(), c))
				return DISCONNECTED;
		}
		c = Client_Next(c);
	}

	/* Announce all channels to the new server */
	chan = Channel_First();
	while (chan) {
		if (Channel_IsLocal(chan)) {
			chan = Channel_Next(chan);
			continue;
		}
#ifdef IRCPLUS
		/* Send CHANINFO if the peer supports it */
		if (Client_HasFlag(Client, 'C')) {
			if (!Send_CHANINFO(Client, chan))
				return DISCONNECTED;
		}
#endif

		if (!Announce_Channel(Client, chan))
			return DISCONNECTED;

		/* Get next channel ... */
		chan = Channel_Next(chan);
	}

#ifdef IRCPLUS
	if (Client_HasFlag(Client, 'L')) {
		LogDebug("Synchronizing INVITE- and BAN-lists ...");
		if (!Synchronize_Lists(Client))
			return DISCONNECTED;
	}
#endif

	if (!IRC_WriteStrClient(Client, "PING :%s",
	    Client_ID(Client_ThisServer())))
		return DISCONNECTED;

	return CONNECTED;
} /* IRC_Num_ENDOFMOTD */
예제 #4
0
/**
 * Handler for the IRC command "SERVER".
 * See RFC 2813 section 4.1.2.
 */
GLOBAL bool
IRC_SERVER( CLIENT *Client, REQUEST *Req )
{
	char str[LINE_LEN];
	CLIENT *from, *c;
	int i;
	CONN_ID con;
	
	assert( Client != NULL );
	assert( Req != NULL );

	/* Return an error if this is not a local client */
	if (Client_Conn(Client) <= NONE)
		return IRC_WriteStrClient(Client, ERR_UNKNOWNCOMMAND_MSG,
					  Client_ID(Client), Req->command);

	if (Client_Type(Client) == CLIENT_GOTPASS ||
	    Client_Type(Client) == CLIENT_GOTPASS_2813) {
		/* We got a PASS command from the peer, and now a SERVER
		 * command: the peer tries to register itself as a server. */
		LogDebug("Connection %d: got SERVER command (new server link) ...",
			Client_Conn(Client));

		if(( Req->argc != 2 ) && ( Req->argc != 3 )) return IRC_WriteStrClient( Client, ERR_NEEDMOREPARAMS_MSG, Client_ID( Client ), Req->command );

		/* Ist this server configured on out side? */
		for( i = 0; i < MAX_SERVERS; i++ ) if( strcasecmp( Req->argv[0], Conf_Server[i].name ) == 0 ) break;
		if( i >= MAX_SERVERS )
		{
			Log( LOG_ERR, "Connection %d: Server \"%s\" not configured here!", Client_Conn( Client ), Req->argv[0] );
			Conn_Close( Client_Conn( Client ), NULL, "Server not configured here", true);
			return DISCONNECTED;
		}
		if( strcmp( Client_Password( Client ), Conf_Server[i].pwd_in ) != 0 )
		{
			/* wrong password */
			Log( LOG_ERR, "Connection %d: Got bad password from server \"%s\"!", Client_Conn( Client ), Req->argv[0] );
			Conn_Close( Client_Conn( Client ), NULL, "Bad password", true);
			return DISCONNECTED;
		}
		
		/* Is there a registered server with this ID? */
		if( ! Client_CheckID( Client, Req->argv[0] )) return DISCONNECTED;

		Client_SetID( Client, Req->argv[0] );
		Client_SetHops( Client, 1 );
		Client_SetInfo( Client, Req->argv[Req->argc - 1] );

		/* Is this server registering on our side, or are we connecting to
		 * a remote server? */
		con = Client_Conn(Client);
		if (Client_Token(Client) != TOKEN_OUTBOUND) {
			/* Incoming connection, send user/pass */
			if (!IRC_WriteStrClient(Client, "PASS %s %s",
						Conf_Server[i].pwd_out,
						NGIRCd_ProtoID)
			    || !IRC_WriteStrClient(Client, "SERVER %s 1 :%s",
						   Conf_ServerName,
						   Conf_ServerInfo)) {
				    Conn_Close(con, "Unexpected server behavior!",
					       NULL, false);
				    return DISCONNECTED;
			}
			Client_SetIntroducer(Client, Client);
			Client_SetToken(Client, 1);
		} else {
			/* outgoing connect, we already sent a SERVER and PASS
			 * command to the peer */
			Client_SetToken(Client, atoi(Req->argv[1]));
		}

		/* Mark this connection as belonging to an configured server */
		Conf_SetServer(i, con);

		/* Check protocol level */
		if (Client_Type(Client) == CLIENT_GOTPASS) {
			/* We got a "simple" PASS command, so the peer is
			 * using the protocol as defined in RFC 1459. */
			if (! (Conn_Options(con) & CONN_RFC1459))
				Log(LOG_INFO,
				    "Switching connection %d (\"%s\") to RFC 1459 compatibility mode.",
				    con, Client_ID(Client));
			Conn_SetOption(con, CONN_RFC1459);
		}

		Client_SetType(Client, CLIENT_UNKNOWNSERVER);

#ifdef ZLIB
		if (strchr(Client_Flags(Client), 'Z') && !Zip_InitConn(con)) {
			Conn_Close( con, "Can't inizialize compression (zlib)!", NULL, false );
			return DISCONNECTED;
		}
#endif

#ifdef IRCPLUS
		if (strchr(Client_Flags(Client), 'H')) {
			LogDebug("Peer supports IRC+ extended server handshake ...");
			if (!IRC_Send_ISUPPORT(Client))
				return DISCONNECTED;
			return IRC_WriteStrClient(Client, RPL_ENDOFMOTD_MSG,
						  Client_ID(Client));
		} else {
#endif
			if (Conf_MaxNickLength != CLIENT_NICK_LEN_DEFAULT)
				Log(LOG_CRIT,
				    "Attention: this server uses a non-standard nick length, but the peer doesn't support the IRC+ extended server handshake!");
#ifdef IRCPLUS
		}
#endif

		return IRC_Num_ENDOFMOTD(Client, Req);
	}
	else if( Client_Type( Client ) == CLIENT_SERVER )
	{
		/* New server is being introduced to the network */

		if( Req->argc != 4 ) return IRC_WriteStrClient( Client, ERR_NEEDMOREPARAMS_MSG, Client_ID( Client ), Req->command );

		/* check for existing server with same ID */
		if( ! Client_CheckID( Client, Req->argv[0] )) return DISCONNECTED;

		from = Client_Search( Req->prefix );
		if( ! from )
		{
			/* Uh, Server, that introduced the new server is unknown?! */
			Log( LOG_ALERT, "Unknown ID in prefix of SERVER: \"%s\"! (on connection %d)", Req->prefix, Client_Conn( Client ));
			Conn_Close( Client_Conn( Client ), NULL, "Unknown ID in prefix of SERVER", true);
			return DISCONNECTED;
		}

		c = Client_NewRemoteServer(Client, Req->argv[0], from, atoi(Req->argv[1]), atoi(Req->argv[2]), Req->argv[3], true);
		if (!c) {
			Log( LOG_ALERT, "Can't create client structure for server! (on connection %d)", Client_Conn( Client ));
			Conn_Close( Client_Conn( Client ), NULL, "Can't allocate client structure for remote server", true);
			return DISCONNECTED;
		}

		if(( Client_Hops( c ) > 1 ) && ( Req->prefix[0] )) snprintf( str, sizeof( str ), "connected to %s, ", Client_ID( from ));
		else strcpy( str, "" );
		Log( LOG_NOTICE|LOG_snotice, "Server \"%s\" registered (via %s, %s%d hop%s).", Client_ID( c ), Client_ID( Client ), str, Client_Hops( c ), Client_Hops( c ) > 1 ? "s": "" );

		/* notify other servers */
		IRC_WriteStrServersPrefix( Client, from, "SERVER %s %d %d :%s", Client_ID( c ), Client_Hops( c ) + 1, Client_MyToken( c ), Client_Info( c ));

		return CONNECTED;
	} else
		return IRC_WriteStrClient(Client, ERR_NEEDMOREPARAMS_MSG,
					  Client_ID(Client), Req->command);
} /* IRC_SERVER */
예제 #5
0
파일: irc-login.c 프로젝트: husemann/ngircd
/**
 * Handler for the IRC "PASS" command.
 *
 * See RFC 2813 section 4.1.1, and RFC 2812 section 3.1.1.
 *
 * @param Client	The client from which this command has been received.
 * @param Req		Request structure with prefix and all parameters.
 * @returns		CONNECTED or DISCONNECTED.
 */
GLOBAL bool
IRC_PASS( CLIENT *Client, REQUEST *Req )
{
	char *type, *orig_flags;
	int protohigh, protolow;

	assert( Client != NULL );
	assert( Req != NULL );

	/* Return an error if this is not a local client */
	if (Client_Conn(Client) <= NONE)
		return IRC_WriteStrClient(Client, ERR_UNKNOWNCOMMAND_MSG,
					  Client_ID(Client), Req->command);

	if (Client_Type(Client) == CLIENT_UNKNOWN && Req->argc == 1) {
		/* Not yet registered "unknown" connection, PASS with one
		 * argument: either a regular client, service, or server
		 * using the old RFC 1459 section 4.1.1 syntax. */
		LogDebug("Connection %d: got PASS command (RFC 1459) ...",
			 Client_Conn(Client));
	} else if ((Client_Type(Client) == CLIENT_UNKNOWN ||
		    Client_Type(Client) == CLIENT_UNKNOWNSERVER) &&
		   (Req->argc == 3 || Req->argc == 4)) {
		/* Not yet registered "unknown" connection or outgoing server
		 * link, PASS with three or four argument: server using the
		 * RFC 2813 section 4.1.1 syntax. */
		LogDebug("Connection %d: got PASS command (RFC 2813, new server link) ...",
			 Client_Conn(Client));
	} else if (Client_Type(Client) == CLIENT_UNKNOWN ||
		   Client_Type(Client) == CLIENT_UNKNOWNSERVER) {
		/* Unregistered connection, but wrong number of arguments: */
		return IRC_WriteStrClient(Client, ERR_NEEDMOREPARAMS_MSG,
					  Client_ID(Client), Req->command);
	} else {
		/* Registered connection, PASS command is not allowed! */
		return IRC_WriteStrClient(Client, ERR_ALREADYREGISTRED_MSG,
					  Client_ID(Client));
	}

	Conn_SetPassword(Client_Conn(Client), Req->argv[0]);

	/* Protocol version */
	if (Req->argc >= 2 && strlen(Req->argv[1]) >= 4) {
		int c2, c4;

		c2 = Req->argv[1][2];
		c4 = Req->argv[1][4];

		Req->argv[1][4] = '\0';
		protolow = atoi(&Req->argv[1][2]);
		Req->argv[1][2] = '\0';
		protohigh = atoi(Req->argv[1]);

		Req->argv[1][2] = c2;
		Req->argv[1][4] = c4;

		Client_SetType(Client, CLIENT_GOTPASS_2813);
	} else {
		protohigh = protolow = 0;
		Client_SetType(Client, CLIENT_GOTPASS);
	}

	/* Protocol type, see doc/Protocol.txt */
	if (Req->argc >= 2 && strlen(Req->argv[1]) > 4)
		type = &Req->argv[1][4];
	else
		type = NULL;

	/* Protocol flags/options */
	if (Req->argc >= 4)
		orig_flags = Req->argv[3];
	else
		orig_flags = "";

	/* Implementation, version and IRC+ flags */
	if (Req->argc >= 3) {
		char *impl, *ptr, *serverver, *flags;

		impl = Req->argv[2];
		ptr = strchr(impl, '|');
		if (ptr)
			*ptr = '\0';

		if (type && strcmp(type, PROTOIRCPLUS) == 0) {
			/* The peer seems to be a server which supports the
			 * IRC+ protocol (see doc/Protocol.txt). */
			serverver = ptr ? ptr + 1 : "?";
			flags = strchr(ptr ? serverver : impl, ':');
			if (flags) {
				*flags = '\0';
				flags++;
			} else
				flags = "";
			Log(LOG_INFO,
			    "Peer on conenction %d announces itself as %s-%s using protocol %d.%d/IRC+ (flags: \"%s\").",
			    Client_Conn(Client), impl, serverver,
			    protohigh, protolow, flags);
		} else {
			/* The peer seems to be a server supporting the
			 * "original" IRC protocol (RFC 2813). */
			if (strchr(orig_flags, 'Z'))
				flags = "Z";
			else
				flags = "";
			Log(LOG_INFO,
			    "Peer on connection %d announces itself as \"%s\" using protocol %d.%d (flags: \"%s\").",
			    Client_Conn(Client), impl,
			    protohigh, protolow, flags);
		}
		Client_SetFlags(Client, flags);
	}

	return CONNECTED;
} /* IRC_PASS */
예제 #6
0
파일: irc-login.c 프로젝트: husemann/ngircd
/**
 * Handler for the IRC "USER" command.
 *
 * See RFC 2812, 3.1.3 "User message".
 *
 * @param Client	The client from which this command has been received.
 * @param Req		Request structure with prefix and all parameters.
 * @returns		CONNECTED or DISCONNECTED.
 */
GLOBAL bool
IRC_USER(CLIENT * Client, REQUEST * Req)
{
	CLIENT *c;
	char *ptr;

	assert(Client != NULL);
	assert(Req != NULL);

	if (Client_Type(Client) == CLIENT_GOTNICK ||
#ifndef STRICT_RFC
	    Client_Type(Client) == CLIENT_UNKNOWN ||
#endif
	    Client_Type(Client) == CLIENT_GOTPASS)
	{
		/* New connection */
		if (Req->argc != 4)
			return IRC_WriteStrClient(Client,
						  ERR_NEEDMOREPARAMS_MSG,
						  Client_ID(Client),
						  Req->command);

		/* User name: only alphanumeric characters and limited
		   punctuation is allowed.*/
		ptr = Req->argv[0];
		while (*ptr) {
			if (!isalnum(*ptr) &&
			    *ptr != '+' && *ptr != '-' &&
			    *ptr != '.' && *ptr != '_') {
				Conn_Close(Client_Conn(Client), NULL,
					   "Invalid user name", true);
				return DISCONNECTED;
			}
			ptr++;
		}

#ifdef IDENTAUTH
		ptr = Client_User(Client);
		if (!ptr || !*ptr || *ptr == '~')
			Client_SetUser(Client, Req->argv[0], false);
#else
		Client_SetUser(Client, Req->argv[0], false);
#endif
		Client_SetOrigUser(Client, Req->argv[0]);

		/* "Real name" or user info text: Don't set it to the empty
		 * string, the original ircd can't deal with such "real names"
		 * (e. g. "USER user * * :") ... */
		if (*Req->argv[3])
			Client_SetInfo(Client, Req->argv[3]);
		else
			Client_SetInfo(Client, "-");

		LogDebug("Connection %d: got valid USER command ...",
		    Client_Conn(Client));
		if (Client_Type(Client) == CLIENT_GOTNICK)
			return Login_User(Client);
		else
			Client_SetType(Client, CLIENT_GOTUSER);
		return CONNECTED;

	} else if (Client_Type(Client) == CLIENT_SERVER ||
		   Client_Type(Client) == CLIENT_SERVICE) {
		/* Server/service updating an user */
		if (Req->argc != 4)
			return IRC_WriteStrClient(Client,
						  ERR_NEEDMOREPARAMS_MSG,
						  Client_ID(Client),
						  Req->command);
		c = Client_Search(Req->prefix);
		if (!c)
			return IRC_WriteStrClient(Client, ERR_NOSUCHNICK_MSG,
						  Client_ID(Client),
						  Req->prefix);

		Client_SetUser(c, Req->argv[0], true);
		Client_SetOrigUser(c, Req->argv[0]);
		Client_SetHostname(c, Req->argv[1]);
		Client_SetInfo(c, Req->argv[3]);

		LogDebug("Connection %d: got valid USER command for \"%s\".",
			 Client_Conn(Client), Client_Mask(c));

		/* RFC 1459 style user registration?
		 * Introduce client to network: */
		if (Client_Type(c) == CLIENT_GOTNICK)
			Client_Introduce(Client, c, CLIENT_USER);

		return CONNECTED;
	} else if (Client_Type(Client) == CLIENT_USER) {
		/* Already registered connection */
		return IRC_WriteStrClient(Client, ERR_ALREADYREGISTRED_MSG,
					  Client_ID(Client));
	} else {
		/* Unexpected/invalid connection state? */
		return IRC_WriteStrClient(Client, ERR_NOTREGISTERED_MSG,
					  Client_ID(Client));
	}
} /* IRC_USER */
예제 #7
0
파일: irc-login.c 프로젝트: husemann/ngircd
/**
 * Handler for the IRC "NICK" command.
 *
 * See RFC 2812, 3.1.2 "Nick message", and RFC 2813, 4.1.3 "Nick".
 *
 * This function implements the IRC command "NICK" which is used to register
 * with the server, to change already registered nicknames and to introduce
 * new users which are connected to other servers.
 *
 * @param Client	The client from which this command has been received.
 * @param Req		Request structure with prefix and all parameters.
 * @returns		CONNECTED or DISCONNECTED.
 */
GLOBAL bool
IRC_NICK( CLIENT *Client, REQUEST *Req )
{
	CLIENT *intr_c, *target, *c;
	char *nick, *user, *hostname, *modes, *info;
	int token, hops;

	assert( Client != NULL );
	assert( Req != NULL );

	/* Some IRC clients, for example BitchX, send the NICK and USER
	 * commands in the wrong order ... */
	if(Client_Type(Client) == CLIENT_UNKNOWN
	    || Client_Type(Client) == CLIENT_GOTPASS
	    || Client_Type(Client) == CLIENT_GOTNICK
#ifndef STRICT_RFC
	    || Client_Type(Client) == CLIENT_GOTUSER
#endif
	    || Client_Type(Client) == CLIENT_USER
	    || Client_Type(Client) == CLIENT_SERVICE
	    || (Client_Type(Client) == CLIENT_SERVER && Req->argc == 1))
	{
		/* User registration or change of nickname */

		/* Wrong number of arguments? */
		if( Req->argc != 1 )
			return IRC_WriteStrClient( Client, ERR_NEEDMOREPARAMS_MSG,
						   Client_ID( Client ),
						   Req->command );

		/* Search "target" client */
		if( Client_Type( Client ) == CLIENT_SERVER )
		{
			target = Client_Search( Req->prefix );
			if( ! target )
				return IRC_WriteStrClient( Client,
							   ERR_NOSUCHNICK_MSG,
							   Client_ID( Client ),
							   Req->argv[0] );
		}
		else
		{
			/* Is this a restricted client? */
			if( Client_HasMode( Client, 'r' ))
				return IRC_WriteStrClient( Client,
							   ERR_RESTRICTED_MSG,
							   Client_ID( Client ));

			target = Client;
		}

#ifndef STRICT_RFC
		/* If the clients tries to change to its own nickname we won't
		 * do anything. This is how the original ircd behaves and some
		 * clients (for example Snak) expect it to be like this.
		 * But I doubt that this is "really the right thing" ... */
		if( strcmp( Client_ID( target ), Req->argv[0] ) == 0 )
			return CONNECTED;
#endif

		/* Check that the new nickname is available. Special case:
		 * the client only changes from/to upper to lower case. */
		if( strcasecmp( Client_ID( target ), Req->argv[0] ) != 0 )
		{
			if( ! Client_CheckNick( target, Req->argv[0] ))
				return CONNECTED;
		}

		if (Client_Type(target) != CLIENT_USER &&
		    Client_Type(target) != CLIENT_SERVICE &&
		    Client_Type(target) != CLIENT_SERVER) {
			/* New client */
			LogDebug("Connection %d: got valid NICK command ...",
			     Client_Conn( Client ));

			/* Register new nickname of this client */
			Client_SetID( target, Req->argv[0] );

#ifndef STRICT_RFC
			if (Conf_AuthPing) {
				Conn_SetAuthPing(Client_Conn(Client), rand());
				IRC_WriteStrClient(Client, "PING :%ld",
					Conn_GetAuthPing(Client_Conn(Client)));
				LogDebug("Connection %d: sent AUTH PING %ld ...",
					Client_Conn(Client),
					Conn_GetAuthPing(Client_Conn(Client)));
			}
#endif

			/* If we received a valid USER command already then
			 * register the new client! */
			if( Client_Type( Client ) == CLIENT_GOTUSER )
				return Login_User( Client );
			else
				Client_SetType( Client, CLIENT_GOTNICK );
		} else {
			/* Nickname change */
			if (Client_Conn(target) > NONE) {
				/* Local client */
				Log(LOG_INFO,
				    "%s \"%s\" changed nick (connection %d): \"%s\" -> \"%s\".",
				    Client_TypeText(target), Client_Mask(target),
				    Client_Conn(target), Client_ID(target),
				    Req->argv[0]);
				Conn_UpdateIdle(Client_Conn(target));
			} else {
				/* Remote client */
				LogDebug("%s \"%s\" changed nick: \"%s\" -> \"%s\".",
					 Client_TypeText(target),
					 Client_Mask(target), Client_ID(target),
					 Req->argv[0]);
			}

			/* Inform all users and servers (which have to know)
			 * of this nickname change */
			if( Client_Type( Client ) == CLIENT_USER )
				IRC_WriteStrClientPrefix( Client, Client,
							  "NICK :%s",
							  Req->argv[0] );
			IRC_WriteStrServersPrefix( Client, target,
						   "NICK :%s", Req->argv[0] );
			IRC_WriteStrRelatedPrefix( target, target, false,
						   "NICK :%s", Req->argv[0] );

			/* Register old nickname for WHOWAS queries */
			Client_RegisterWhowas( target );

			/* Save new nickname */
			Client_SetID( target, Req->argv[0] );

			IRC_SetPenalty( target, 2 );
		}

		return CONNECTED;
	} else if(Client_Type(Client) == CLIENT_SERVER ||
		  Client_Type(Client) == CLIENT_SERVICE) {
		/* Server or service introduces new client */

		/* Bad number of parameters? */
		if (Req->argc != 2 && Req->argc != 7)
			return IRC_WriteStrClient(Client, ERR_NEEDMOREPARAMS_MSG,
						  Client_ID(Client), Req->command);

		if (Req->argc >= 7) {
			/* RFC 2813 compatible syntax */
			nick = Req->argv[0];
			hops = atoi(Req->argv[1]);
			user = Req->argv[2];
			hostname = Req->argv[3];
			token = atoi(Req->argv[4]);
			modes = Req->argv[5] + 1;
			info = Req->argv[6];
		} else {
			/* RFC 1459 compatible syntax */
			nick = Req->argv[0];
			hops = 1;
			user = Req->argv[0];
			hostname = Client_ID(Client);
			token = atoi(Req->argv[1]);
			modes = "";
			info = Req->argv[0];
		}

		c = Client_Search(nick);
		if(c) {
			/*
			 * the new nick is already present on this server:
			 * the new and the old one have to be disconnected now.
			 */
			Log( LOG_ERR, "Server %s introduces already registered nick \"%s\"!", Client_ID( Client ), Req->argv[0] );
			Kill_Nick( Req->argv[0], "Nick collision" );
			return CONNECTED;
		}

		/* Find the Server this client is connected to */
		intr_c = Client_GetFromToken(Client, token);
		if( ! intr_c )
		{
			Log( LOG_ERR, "Server %s introduces nick \"%s\" on unknown server!?", Client_ID( Client ), Req->argv[0] );
			Kill_Nick( Req->argv[0], "Unknown server" );
			return CONNECTED;
		}

		c = Client_NewRemoteUser(intr_c, nick, hops, user, hostname,
					 token, modes, info, true);
		if( ! c )
		{
			/* out of memory, need to disconnect client to keep network state consistent */
			Log( LOG_ALERT, "Can't create client structure! (on connection %d)", Client_Conn( Client ));
			Kill_Nick( Req->argv[0], "Server error" );
			return CONNECTED;
		}

		/* RFC 2813: client is now fully registered, inform all the
		 * other servers about the new user.
		 * RFC 1459: announce the new client only after receiving the
		 * USER command, first we need more information! */
		if (Req->argc < 7) {
			LogDebug("Client \"%s\" is being registered (RFC 1459) ...",
				 Client_Mask(c));
			Client_SetType(c, CLIENT_GOTNICK);
		} else
			Client_Introduce(Client, c, CLIENT_USER);

		return CONNECTED;
	}
	else return IRC_WriteStrClient( Client, ERR_ALREADYREGISTRED_MSG, Client_ID( Client ));
} /* IRC_NICK */