xref: /dports/irc/ngircd/ngircd-26.1/src/ngircd/conn.c

/*
 * ngIRCd -- The Next Generation IRC Daemon
 * Copyright (c)2001-2019 Alexander Barton (alex@barton.de) and Contributors.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * Please read the file COPYING, README and AUTHORS for more information.
 */

#define CONN_MODULE
#define CONN_MODULE_GLOBAL_INIT

#include "portab.h"

/**
 * @file
 * Connection management
 */

/* Additionan debug messages related to buffer handling: 0=off / 1=on */
#define DEBUG_BUFFER 0

#include <assert.h>
#ifdef PROTOTYPES
# include <stdarg.h>
#else
# include <varargs.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <netinet/in.h>

#ifdef HAVE_NETINET_IP_H
# ifdef HAVE_NETINET_IN_SYSTM_H
#  include <netinet/in_systm.h>
# endif
# include <netinet/ip.h>
#endif

#ifdef TCPWRAP
# include <tcpd.h>			/* for TCP Wrappers */
#endif

#include "conn.h"

#include "ngircd.h"
#include "class.h"
#ifdef ICONV
# include "conn-encoding.h"
#endif
#include "conn-ssl.h"
#include "conn-zip.h"
#include "conn-func.h"
#include "io.h"
#include "log.h"
#include "ng_ipaddr.h"
#include "parse.h"
#include "resolve.h"

#define SERVER_WAIT (NONE - 1)		/** "Wait for outgoing connection" flag */

#define MAX_COMMANDS 3			/** Max. commands per loop for users */
#define MAX_COMMANDS_SERVER_MIN 10	/** Min. commands per loop for servers */
#define MAX_COMMANDS_SERVICE 10		/** Max. commands per loop for services */

#define SD_LISTEN_FDS_START 3		/** systemd(8) socket activation offset */

#define THROTTLE_CMDS 1			/** Throttling: max commands reached */
#define THROTTLE_BPS 2			/** Throttling: max bps reached */

static bool Handle_Write PARAMS(( CONN_ID Idx ));
static bool Conn_Write PARAMS(( CONN_ID Idx, char *Data, size_t Len ));
static int New_Connection PARAMS(( int Sock, bool IsSSL ));
static CONN_ID Socket2Index PARAMS(( int Sock ));
static void Read_Request PARAMS(( CONN_ID Idx ));
static unsigned int Handle_Buffer PARAMS(( CONN_ID Idx ));
static void Check_Connections PARAMS(( void ));
static void Check_Servers PARAMS(( void ));
static void Init_Conn_Struct PARAMS(( CONN_ID Idx ));
static bool Init_Socket PARAMS(( int Sock ));
static void New_Server PARAMS(( int Server, ng_ipaddr_t *dest ));
static void Simple_Message PARAMS(( int Sock, const char *Msg ));
static int NewListener PARAMS(( const char *listen_addr, UINT16 Port ));
static void Account_Connection PARAMS((void));
static void Throttle_Connection PARAMS((const CONN_ID Idx, CLIENT *Client,
					const int Reason, unsigned int Value));

static array My_Listeners;
static array My_ConnArray;
static size_t NumConnections, NumConnectionsMax, NumConnectionsAccepted;

#ifdef TCPWRAP
int allow_severity = LOG_INFO;
int deny_severity = LOG_ERR;
#endif

static void server_login PARAMS((CONN_ID idx));

#ifdef SSL_SUPPORT
extern struct SSLOptions Conf_SSLOptions;
static bool SSL_WantRead PARAMS((const CONNECTION *c));
static bool SSL_WantWrite PARAMS((const CONNECTION *c));
static void cb_listen_ssl PARAMS((int sock, short irrelevant));
static void cb_connserver_login_ssl PARAMS((int sock, short what));
static void cb_clientserver_ssl PARAMS((int sock, short what));
#endif
static void cb_Read_Resolver_Result PARAMS((int sock, UNUSED short what));
static void cb_Connect_to_Server PARAMS((int sock, UNUSED short what));
static void cb_clientserver PARAMS((int sock, short what));

time_t idle_t = 0;

/**
 * Get number of sockets available from systemd(8).
 *
 * ngIRCd needs to implement its own sd_listen_fds(3) function and can't
 * use the one provided by systemd itself, because the sockets will be
 * used in a forked child process with a new PID, and this would trigger
 * an error in the standard implementation.
 *
 * @return Number of sockets available, -1 if sockets have already been
 *         initialized, or 0 when no sockets have been passed.
 */
static int
my_sd_listen_fds(void)
{
	const char *e;
	int count;

	/* Check if LISTEN_PID exists; but we ignore the result, because
	 * normally ngircd forks a child before checking this, and therefore
	 * the PID set in the environment is always wrong ... */
	e = getenv("LISTEN_PID");
	if (!e || !*e)
		return 0;

	e = getenv("LISTEN_FDS");
	if (!e || !*e)
		return -1;
	count = atoi(e);
#ifdef HAVE_UNSETENV
	unsetenv("LISTEN_FDS");
#endif

	return count;
}

/**
 * IO callback for listening sockets: handle new connections. This callback
 * gets called when a new non-SSL connection should be accepted.
 *
 * @param sock		Socket descriptor.
 * @param irrelevant	(ignored IO specification)
 */
static void
cb_listen(int sock, short irrelevant)
{
	(void) irrelevant;
	(void) New_Connection(sock, false);
}

/**
 * IO callback for new outgoing non-SSL server connections.
 *
 * @param sock	Socket descriptor.
 * @param what	IO specification (IO_WANTREAD/IO_WANTWRITE/...).
 */
static void
cb_connserver(int sock, UNUSED short what)
{
	int res, err, server;
	socklen_t sock_len;
	CONN_ID idx = Socket2Index( sock );

	if (idx <= NONE) {
		io_close(sock);
		return;
	}

	assert(what & IO_WANTWRITE);

	/* Make sure that the server is still configured; it could have been
	 * removed in the meantime! */
	server = Conf_GetServer(idx);
	if (server < 0) {
		Log(LOG_ERR, "Connection on socket %d to \"%s\" aborted!",
		    sock, My_Connections[idx].host);
		Conn_Close(idx, "Connection aborted", NULL, false);
		return;
	}

	/* connect() finished, get result. */
	sock_len = (socklen_t)sizeof(err);
	res = getsockopt(My_Connections[idx].sock, SOL_SOCKET, SO_ERROR,
			 &err, &sock_len );
	assert(sock_len == sizeof(err));

	/* Error while connecting? */
 	if ((res != 0) || (err != 0)) {
 		if (res != 0)
 			Log(LOG_CRIT, "getsockopt (connection %d): %s!",
 			    idx, strerror(errno));
 		else
 			Log(LOG_CRIT,
 			    "Can't connect socket to \"%s:%d\" (connection %d): %s!",
			    My_Connections[idx].host, Conf_Server[server].port,
 			    idx, strerror(err));

		Conn_Close(idx, "Can't connect", NULL, false);

		if (ng_ipaddr_af(&Conf_Server[server].dst_addr[0])) {
			/* more addresses to try... */
			New_Server(server, &Conf_Server[server].dst_addr[0]);
			/* connection to dst_addr[0] is now in progress, so
			 * remove this address... */
			Conf_Server[server].dst_addr[0] =
				Conf_Server[server].dst_addr[1];
			memset(&Conf_Server[server].dst_addr[1], 0,
			       sizeof(Conf_Server[server].dst_addr[1]));
		}
		return;
	}

	/* connect() succeeded, remove all additional addresses */
	memset(&Conf_Server[server].dst_addr, 0,
	       sizeof(Conf_Server[server].dst_addr));

	Conn_OPTION_DEL( &My_Connections[idx], CONN_ISCONNECTING );
#ifdef SSL_SUPPORT
	if ( Conn_OPTION_ISSET( &My_Connections[idx], CONN_SSL_CONNECT )) {
		io_event_setcb( sock, cb_connserver_login_ssl );
		io_event_add( sock, IO_WANTWRITE|IO_WANTREAD );
		return;
	}
#endif
	server_login(idx);
}

/**
 * Login to a remote server.
 *
 * @param idx	Connection index.
 */
static void
server_login(CONN_ID idx)
{
	Log(LOG_INFO,
	    "Connection %d (socket %d) with \"%s:%d\" established. Now logging in ...",
	    idx, My_Connections[idx].sock, My_Connections[idx].host,
	    Conf_Server[Conf_GetServer(idx)].port);

	io_event_setcb( My_Connections[idx].sock, cb_clientserver);
	io_event_add( My_Connections[idx].sock, IO_WANTREAD|IO_WANTWRITE);

	/* Send PASS and SERVER command to peer */
	Conn_WriteStr(idx, "PASS %s %s",
		      Conf_Server[Conf_GetServer( idx )].pwd_out, NGIRCd_ProtoID);
	Conn_WriteStr(idx, "SERVER %s :%s",
		      Conf_ServerName, Conf_ServerInfo);
}

/**
 * IO callback for established non-SSL client and server connections.
 *
 * @param sock	Socket descriptor.
 * @param what	IO specification (IO_WANTREAD/IO_WANTWRITE/...).
 */
static void
cb_clientserver(int sock, short what)
{
	CONN_ID idx = Socket2Index(sock);

	if (idx <= NONE) {
		io_close(sock);
		return;
	}

#ifdef SSL_SUPPORT
	if (what & IO_WANTREAD
	    || (Conn_OPTION_ISSET(&My_Connections[idx], CONN_SSL_WANT_WRITE))) {
		/* if TLS layer needs to write additional data, call
		 * Read_Request() instead so that SSL/TLS can continue */
		Read_Request(idx);
	}
#else
	if (what & IO_WANTREAD)
		Read_Request(idx);
#endif
	if (what & IO_WANTWRITE)
		Handle_Write(idx);
}

/**
 * Initialize connection module.
 */
GLOBAL void
Conn_Init( void )
{
	int size;

	/* Initialize the "connection pool".
	 * FIXME: My_Connetions/Pool_Size is needed by other parts of the
	 * code; remove them! */
	Pool_Size = 0;
	size = Conf_MaxConnections > 0 ? Conf_MaxConnections : CONNECTION_POOL;
	if (Socket2Index(size) <= NONE) {
		Log(LOG_EMERG, "Failed to initialize connection pool!");
		exit(1);
	}

	/* Initialize "listener" array. */
	array_free( &My_Listeners );
} /* Conn_Init */

/**
 * Clean up connection module.
 */
GLOBAL void
Conn_Exit( void )
{
	CONN_ID idx;

	Conn_ExitListeners();

	LogDebug("Shutting down all connections ..." );
	for( idx = 0; idx < Pool_Size; idx++ ) {
		if( My_Connections[idx].sock > NONE ) {
			Conn_Close( idx, NULL, NGIRCd_SignalRestart ?
				"Server going down (restarting)":"Server going down", true );
		}
	}

	array_free(&My_ConnArray);
	My_Connections = NULL;
	Pool_Size = 0;
	io_library_shutdown();
} /* Conn_Exit */

/**
 * Close all sockets (file descriptors) of open connections.
 * This is useful in forked child processes, for example, to make sure that
 * they don't hold connections open that the main process wants to close.
 */
GLOBAL void
Conn_CloseAllSockets(int ExceptOf)
{
	CONN_ID idx;

	for(idx = 0; idx < Pool_Size; idx++) {
		if(My_Connections[idx].sock > NONE &&
		   My_Connections[idx].sock != ExceptOf)
			close(My_Connections[idx].sock);
	}
}

/**
 * Initialize listening ports.
 *
 * @param a		Array containing the ports the daemon should listen on.
 * @param listen_addr	Address the socket should listen on (can be "0.0.0.0").
 * @param func		IO callback function to register.
 * @returns		Number of listening sockets created.
 */
static unsigned int
Init_Listeners(array *a, const char *listen_addr, void (*func)(int,short))
{
	unsigned int created = 0;
	size_t len;
	int fd;
	UINT16 *port;

	len = array_length(a, sizeof (UINT16));
	port = array_start(a);
	while (len--) {
		fd = NewListener(listen_addr, *port);
		if (fd < 0) {
			port++;
			continue;
		}
		if (!io_event_create( fd, IO_WANTREAD, func )) {
			Log(LOG_ERR,
			    "io_event_create(): Can't add fd %d (port %u): %s!",
			    fd, (unsigned int) *port, strerror(errno));
			close(fd);
			port++;
			continue;
		}
		created++;
		port++;
	}
	return created;
}

/**
 * Initialize all listening sockets.
 *
 * @returns	Number of created listening sockets
 */
GLOBAL unsigned int
Conn_InitListeners( void )
{
	/* Initialize ports on which the server should accept connections */
	unsigned int created = 0;
	char *af_str, *copy, *listen_addr;
	int count, fd, i, addr_len;
	ng_ipaddr_t addr;

	assert(Conf_ListenAddress);

	count = my_sd_listen_fds();
	if (count < 0) {
		Log(LOG_INFO,
		    "Not re-initializing listening sockets of systemd(8) ...");
		return 0;
	}
	if (count > 0) {
		/* systemd(8) passed sockets to us, so don't try to initialize
		 * listening sockets on our own but use the passed ones */
		LogDebug("Initializing %d systemd sockets ...", count);
		for (i = 0; i < count; i++) {
			fd = SD_LISTEN_FDS_START + i;
			addr_len = (int)sizeof(addr);
			getsockname(fd, (struct sockaddr *)&addr,
				    (socklen_t*)&addr_len);
#ifdef WANT_IPV6
			if (addr.sin4.sin_family != AF_INET
			    && addr.sin4.sin_family != AF_INET6)
#else
			if (addr.sin4.sin_family != AF_INET)
#endif
			{
				/* Socket is of unsupported type! For example,
				 * systemd passed in an IPv6 socket but ngIRCd
				 * isn't compiled with IPv6 support. */
				switch (addr.sin4.sin_family)
				{
					case AF_UNSPEC: af_str = "AF_UNSPEC"; break;
					case AF_UNIX: af_str = "AF_UNIX"; break;
					case AF_INET: af_str = "AF_INET"; break;
#ifdef AF_INET6
					case AF_INET6: af_str = "AF_INET6"; break;
#endif
#ifdef AF_NETLINK
					case AF_NETLINK: af_str = "AF_NETLINK"; break;
#endif
					default: af_str = "unknown"; break;
				}
				Log(LOG_CRIT,
				    "Socket %d is of unsupported type \"%s\" (%d), have to ignore it!",
				    fd, af_str, addr.sin4.sin_family);
				close(fd);
				continue;
			}

			Init_Socket(fd);
			if (!io_event_create(fd, IO_WANTREAD, cb_listen)) {
				Log(LOG_ERR,
				    "io_event_create(): Can't add fd %d: %s!",
				    fd, strerror(errno));
				continue;
			}
			Log(LOG_INFO,
			    "Initialized socket %d from systemd(8): %s:%d.", fd,
			    ng_ipaddr_tostr(&addr), ng_ipaddr_getport(&addr));
			created++;
		}
		return created;
	}

	/* not using systemd socket activation, initialize listening sockets: */

	/* can't use Conf_ListenAddress directly, see below */
	copy = strdup(Conf_ListenAddress);
	if (!copy) {
		Log(LOG_CRIT, "Cannot copy %s: %s", Conf_ListenAddress,
		    strerror(errno));
		return 0;
	}
	listen_addr = strtok(copy, ",");

	while (listen_addr) {
		ngt_TrimStr(listen_addr);
		if (*listen_addr) {
			created += Init_Listeners(&Conf_ListenPorts,
						  listen_addr, cb_listen);
#ifdef SSL_SUPPORT
			created += Init_Listeners(&Conf_SSLOptions.ListenPorts,
						  listen_addr, cb_listen_ssl);
#endif
		}

		listen_addr = strtok(NULL, ",");
	}

	/* Can't free() Conf_ListenAddress here: on REHASH, if the config file
	 * cannot be re-loaded, we'd end up with a NULL Conf_ListenAddress.
	 * Instead, free() takes place in conf.c, before the config file
	 * is being parsed. */
	free(copy);

	return created;
} /* Conn_InitListeners */

/**
 * Shut down all listening sockets.
 */
GLOBAL void
Conn_ExitListeners( void )
{
	/* Close down all listening sockets */
	int *fd;
	size_t arraylen;

	/* Get number of listening sockets to shut down. There can be none
	 * if ngIRCd has been "socket activated" by systemd. */
	arraylen = array_length(&My_Listeners, sizeof (int));
	if (arraylen < 1)
		return;

	Log(LOG_INFO,
	    "Shutting down all listening sockets (%d total) ...", arraylen);
	fd = array_start(&My_Listeners);
	while(arraylen--) {
		assert(fd != NULL);
		assert(*fd >= 0);
		io_close(*fd);
		LogDebug("Listening socket %d closed.", *fd );
		fd++;
	}
	array_free(&My_Listeners);
} /* Conn_ExitListeners */

/**
 * Bind a socket to a specific (source) address.
 *
 * @param addr			Address structure.
 * @param listen_addrstr	Source address as string.
 * @param Port			Port number.
 * @returns			true on success, false otherwise.
 */
static bool
InitSinaddrListenAddr(ng_ipaddr_t *addr, const char *listen_addrstr, UINT16 Port)
{
	bool ret;

	ret = ng_ipaddr_init(addr, listen_addrstr, Port);
	if (!ret) {
		assert(listen_addrstr);
		Log(LOG_CRIT,
		    "Can't listen on [%s]:%u: Failed to parse IP address!",
		    listen_addrstr, Port);
	}
	return ret;
}

/**
 * Set a socket to "IPv6 only". If the given socket doesn't belong to the
 * AF_INET6 family, or the operating system doesn't support this functionality,
 * this function retruns silently.
 *
 * @param af	Address family of the socket.
 * @param sock	Socket handle.
 */
static void
set_v6_only(int af, int sock)
{
#if defined(IPV6_V6ONLY) && defined(WANT_IPV6)
	int on = 1;

	if (af != AF_INET6)
		return;

	if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, (socklen_t)sizeof(on)))
		Log(LOG_ERR, "Could not set IPV6_V6ONLY: %s", strerror(errno));
#else
	(void)af;
	(void)sock;
#endif
}

/**
 * Initialize new listening port.
 *
 * @param listen_addr	Local address to bind the socet to (can be 0.0.0.0).
 * @param Port		Port number on which the new socket should be listening.
 * @returns		file descriptor of the socket or -1 on failure.
 */
static int
NewListener(const char *listen_addr, UINT16 Port)
{
	/* Create new listening socket on specified port */
	ng_ipaddr_t addr;
	int sock, af;

	if (!InitSinaddrListenAddr(&addr, listen_addr, Port))
		return -1;

	af = ng_ipaddr_af(&addr);
	sock = socket(af, SOCK_STREAM, 0);
	if (sock < 0) {
		Log(LOG_CRIT, "Can't create socket (af %d) : %s!", af,
		    strerror(errno));
		return -1;
	}

	set_v6_only(af, sock);

	if (!Init_Socket(sock))
		return -1;

	if (bind(sock, (struct sockaddr *)&addr, ng_ipaddr_salen(&addr)) != 0) {
		Log(LOG_CRIT, "Can't bind socket to address %s:%d - %s!",
		    ng_ipaddr_tostr(&addr), Port, strerror(errno));
		close(sock);
		return -1;
	}

	if (listen(sock, 10) != 0) {
		Log(LOG_CRIT, "Can't listen on socket: %s!", strerror(errno));
		close(sock);
		return -1;
	}

	/* keep fd in list so we can close it when ngircd restarts/shuts down */
	if (!array_catb(&My_Listeners, (char *)&sock, sizeof(int))) {
		Log(LOG_CRIT, "Can't add socket to My_Listeners array: %s!",
		    strerror(errno));
		close(sock);
		return -1;
	}

	Log(LOG_INFO, "Now listening on [%s]:%d (socket %d).",
	    ng_ipaddr_tostr(&addr), Port, sock);
	return sock;
} /* NewListener */

/**
 * "Main Loop": Loop until shutdown or restart is signalled.
 *
 * This function loops until a shutdown or restart of ngIRCd is signalled and
 * calls io_dispatch() to check for readable and writable sockets every second.
 * It checks for status changes on pending connections (e. g. when a hostname
 * has been resolved), checks for "penalties" and timeouts, and handles the
 * input buffers.
 */
GLOBAL void
Conn_Handler(void)
{
	int i;
	size_t wdatalen;
	struct timeval tv;
	time_t t;
	bool command_available;

	Log(LOG_NOTICE, "Server \"%s\" (on \"%s\") ready.",
	    Client_ID(Client_ThisServer()), Client_Hostname(Client_ThisServer()));

	while (!NGIRCd_SignalQuit && !NGIRCd_SignalRestart) {
		t = time(NULL);
		command_available = false;

		/* Check configured servers and established links */
		Check_Servers();
		Check_Connections();

		/* Expire outdated class/list items */
		Class_Expire();

		/* Look for non-empty read buffers ... */
		for (i = 0; i < Pool_Size; i++) {
			if ((My_Connections[i].sock > NONE)
			    && (array_bytes(&My_Connections[i].rbuf) > 0)) {
				/* ... and try to handle the received data */
				Handle_Buffer(i);
			}
		}

		/* Look for non-empty write buffers ... */
		for (i = 0; i < Pool_Size; i++) {
			if (My_Connections[i].sock <= NONE)
				continue;

			wdatalen = array_bytes(&My_Connections[i].wbuf);
#ifdef ZLIB
			if (wdatalen > 0 ||
			    array_bytes(&My_Connections[i].zip.wbuf) > 0)
#else
			if (wdatalen > 0)
#endif
			{
#ifdef SSL_SUPPORT
				if (SSL_WantRead(&My_Connections[i]))
					continue;
#endif
				io_event_add(My_Connections[i].sock,
					     IO_WANTWRITE);
			}
		}

		/* Check from which sockets we possibly could read ... */
		for (i = 0; i < Pool_Size; i++) {
			if (My_Connections[i].sock <= NONE)
				continue;
#ifdef SSL_SUPPORT
			if (SSL_WantWrite(&My_Connections[i]))
				/* TLS/SSL layer needs to write data; deal
				 * with this first! */
				continue;
#endif
			if (Proc_InProgress(&My_Connections[i].proc_stat)) {
				/* Wait for completion of forked subprocess
				 * and ignore the socket in the meantime ... */
				io_event_del(My_Connections[i].sock,
					     IO_WANTREAD);
				continue;
			}

			if (Conn_OPTION_ISSET(&My_Connections[i], CONN_ISCONNECTING))
				/* Wait for completion of connect() ... */
				continue;

			if (My_Connections[i].delaytime > t) {
				/* There is a "penalty time" set: ignore socket! */
				io_event_del(My_Connections[i].sock,
					     IO_WANTREAD);
				continue;
			}

			if (array_bytes(&My_Connections[i].rbuf) >= COMMAND_LEN) {
				/* There is still more data in the read buffer
				 * than a single valid command can get long:
				 * so either there is a complete command, or
				 * invalid data. Therefore don't try to read in
				 * even more data from the network but wait for
				 * this command(s) to be handled first! */
				io_event_del(My_Connections[i].sock,
					     IO_WANTREAD);
				command_available = true;
				continue;
			}

			io_event_add(My_Connections[i].sock, IO_WANTREAD);
		}

		/* Don't wait for data when there is still at least one command
		 * available in a read buffer which can be handled immediately;
		 * set the timeout for reading from the network to 1 second
		 * otherwise, which is the granularity with witch we handle
		 * "penalty times" for example.
		 * Note: tv_sec/usec are undefined(!) after io_dispatch()
		 * returns, so we have to set it before each call to it! */
		tv.tv_usec = 0;
		tv.tv_sec = command_available ? 0 : 1;

		/* Wait for activity ... */
		i = io_dispatch(&tv);
		if (i == -1 && errno != EINTR) {
			Log(LOG_EMERG, "Conn_Handler(): io_dispatch(): %s!",
			    strerror(errno));
			Log(LOG_ALERT, "%s exiting due to fatal errors!",
			    PACKAGE_NAME);
			exit(1);
		}

		/* Should ngIRCd timeout when idle? */
		if (Conf_IdleTimeout > 0 && NumConnectionsAccepted > 0
		    && idle_t > 0 && time(NULL) - idle_t >= Conf_IdleTimeout) {
			LogDebug("Server idle timeout reached: %d second%s. Initiating shutdown ...",
				 Conf_IdleTimeout,
				 Conf_IdleTimeout == 1 ? "" : "s");
			NGIRCd_SignalQuit = true;
		}
	}

	if (NGIRCd_SignalQuit)
		Log(LOG_NOTICE | LOG_snotice, "Server going down NOW!");
	else if (NGIRCd_SignalRestart)
		Log(LOG_NOTICE | LOG_snotice, "Server restarting NOW!");
} /* Conn_Handler */

/**
 * Write a text string into the socket of a connection.
 *
 * This function automatically appends CR+LF to the string and validates that
 * the result is a valid IRC message (oversized messages are shortened, for
 * example). Then it calls the Conn_Write() function to do the actual sending.
 *
 * @param Idx		Index fo the connection.
 * @param Format	Format string, see printf().
 * @returns		true on success, false otherwise.
 */
#ifdef PROTOTYPES
GLOBAL bool
Conn_WriteStr(CONN_ID Idx, const char *Format, ...)
#else
GLOBAL bool
Conn_WriteStr(Idx, Format, va_alist)
CONN_ID Idx;
const char *Format;
va_dcl
#endif
{
	char buffer[COMMAND_LEN];
#ifdef ICONV
	char *ptr, *message;
#endif
	size_t len;
	bool ok;
	va_list ap;
	int r;

	assert( Idx > NONE );
	assert( Format != NULL );

#ifdef PROTOTYPES
	va_start( ap, Format );
#else
	va_start( ap );
#endif
	r = vsnprintf(buffer, COMMAND_LEN - 2, Format, ap);
	if (r >= COMMAND_LEN - 2 || r == -1) {
		/*
		 * The string that should be written to the socket is longer
		 * than the allowed size of COMMAND_LEN bytes (including both
		 * the CR and LF characters). This can be caused by the
		 * IRC_WriteXXX() functions when the prefix of this server had
		 * to be added to an already "quite long" command line which
		 * has been received from a regular IRC client, for example.
		 *
		 * We are not allowed to send such "oversized" messages to
		 * other servers and clients, see RFC 2812 2.3 and 2813 3.3
		 * ("these messages SHALL NOT exceed 512 characters in length,
		 * counting all characters including the trailing CR-LF").
		 *
		 * So we have a big problem here: we should send more bytes
		 * to the network than we are allowed to and we don't know
		 * the originator (any more). The "old" behavior of blaming
		 * the receiver ("next hop") is a bad idea (it could be just
		 * an other server only routing the message!), so the only
		 * option left is to shorten the string and to hope that the
		 * result is still somewhat useful ...
		 *
		 * Note:
		 * C99 states that vsnprintf() "returns the number of characters
		 * that would have been printed if the n were unlimited"; but
		 * according to the Linux manual page "glibc until 2.0.6 would
		 * return -1 when the output was truncated" -- so we have to
		 * handle both cases ...
		 *                                                   -alex-
		 */

		strcpy (buffer + sizeof(buffer) - strlen(CUT_TXTSUFFIX) - 2 - 1,
			CUT_TXTSUFFIX);
	}

#ifdef ICONV
	ptr = strchr(buffer + 1, ':');
	if (ptr) {
		ptr++;
		message = Conn_EncodingTo(Idx, ptr);
		if (message != ptr)
			strlcpy(ptr, message, sizeof(buffer) - (ptr - buffer));
	}
#endif

#ifdef SNIFFER
	if (NGIRCd_Sniffer)
		Log(LOG_DEBUG, " -> connection %d: '%s'.", Idx, buffer);
#endif

	len = strlcat( buffer, "\r\n", sizeof( buffer ));
	ok = Conn_Write(Idx, buffer, len);
	My_Connections[Idx].msg_out++;

	va_end( ap );
	return ok;
} /* Conn_WriteStr */

GLOBAL char*
Conn_Password( CONN_ID Idx )
{
	assert( Idx > NONE );
	if (My_Connections[Idx].pwd == NULL)
		return (char*)"\0";
	else
		return My_Connections[Idx].pwd;
} /* Conn_Password */

GLOBAL void
Conn_SetPassword( CONN_ID Idx, const char *Pwd )
{
	assert( Idx > NONE );

	if (My_Connections[Idx].pwd)
		free(My_Connections[Idx].pwd);

	My_Connections[Idx].pwd = strdup(Pwd);
	if (My_Connections[Idx].pwd == NULL) {
		Log(LOG_EMERG, "Can't allocate memory! [Conn_SetPassword]");
		exit(1);
	}
} /* Conn_SetPassword */

/**
 * Append Data to the outbound write buffer of a connection.
 *
 * @param Idx	Index of the connection.
 * @param Data	pointer to the data.
 * @param Len	length of Data.
 * @returns	true on success, false otherwise.
 */
static bool
Conn_Write( CONN_ID Idx, char *Data, size_t Len )
{
	CLIENT *c;
	size_t writebuf_limit = WRITEBUFFER_MAX_LEN;
	assert( Idx > NONE );
	assert( Data != NULL );
	assert( Len > 0 );

	/* Is the socket still open? A previous call to Conn_Write()
	 * may have closed the connection due to a fatal error.
	 * In this case it is sufficient to return an error, as well. */
	if (My_Connections[Idx].sock <= NONE) {
		LogDebug("Skipped write on closed socket (connection %d).", Idx);
		return false;
	}

	/* Make sure that there still exists a CLIENT structure associated
	 * with this connection and check if this is a server or not: */
	c = Conn_GetClient(Idx);
	if (c) {
		/* Servers do get special write buffer limits, so they can
		 * generate all the messages that are required while peering. */
		if (Client_Type(c) == CLIENT_SERVER)
			writebuf_limit = WRITEBUFFER_SLINK_LEN;
	} else
		LogDebug("Write on socket without client (connection %d)!?", Idx);

#ifdef ZLIB
	if ( Conn_OPTION_ISSET( &My_Connections[Idx], CONN_ZIP )) {
		/* Compressed link:
		 * Zip_Buffer() does all the dirty work for us: it flushes
		 * the (pre-)compression buffers if required and handles
		 * all error conditions. */
		if (!Zip_Buffer(Idx, Data, Len))
			return false;
	}
	else
#endif
	{
		/* Uncompressed link:
		 * Check if outbound buffer has enough space for the data. */
		if (array_bytes(&My_Connections[Idx].wbuf) + Len >=
		    WRITEBUFFER_FLUSH_LEN) {
			/* Buffer is full, flush it. Handle_Write deals with
			 * low-level errors, if any. */
			if (!Handle_Write(Idx))
				return false;
		}

		/* When the write buffer is still too big after flushing it,
		 * the connection will be killed. */
		if (array_bytes(&My_Connections[Idx].wbuf) + Len >=
		    writebuf_limit) {
			Log(LOG_NOTICE,
			    "Write buffer space exhausted (connection %d, limit is %lu bytes, %lu bytes new, %lu bytes pending)",
			    Idx, writebuf_limit, Len,
			    (unsigned long)array_bytes(&My_Connections[Idx].wbuf));
			Conn_Close(Idx, "Write buffer space exhausted", NULL, false);
			return false;
		}

		/* Copy data to write buffer */
		if (!array_catb(&My_Connections[Idx].wbuf, Data, Len))
			return false;

		My_Connections[Idx].bytes_out += Len;
	}

	/* Adjust global write counter */
	WCounter += Len;

	return true;
} /* Conn_Write */

/**
 * Shut down a connection.
 *
 * @param Idx		Connection index.
 * @param LogMsg	Message to write to the log or NULL. If no LogMsg
 *			is given, the FwdMsg is logged.
 * @param FwdMsg	Message to forward to remote servers.
 * @param InformClient	If true, inform the client on the connection which is
 *			to be shut down of the reason (FwdMsg) and send
 *			connection statistics before disconnecting it.
 */
GLOBAL void
Conn_Close(CONN_ID Idx, const char *LogMsg, const char *FwdMsg, bool InformClient)
{
	/* Close connection. Open pipes of asynchronous resolver
	 * sub-processes are closed down. */

	CLIENT *c;
	double in_k, out_k;
	UINT16 port;
#ifdef ZLIB
	double in_z_k, out_z_k;
	int in_p, out_p;
#endif

	assert( Idx > NONE );

	/* Is this link already shutting down? */
	if( Conn_OPTION_ISSET( &My_Connections[Idx], CONN_ISCLOSING )) {
		/* Conn_Close() has been called recursively for this link;
		 * probable reason: Handle_Write() failed -- see below. */
		LogDebug("Recursive request to close connection %d!", Idx );
		return;
	}

	assert( My_Connections[Idx].sock > NONE );

	/* Mark link as "closing" */
	Conn_OPTION_ADD( &My_Connections[Idx], CONN_ISCLOSING );

	port = ng_ipaddr_getport(&My_Connections[Idx].addr);
	Log(LOG_INFO, "Shutting down connection %d (%s) with \"%s:%d\" ...", Idx,
	    LogMsg ? LogMsg : FwdMsg, My_Connections[Idx].host, port);

	/* Search client, if any */
	c = Conn_GetClient( Idx );

	/* Should the client be informed? */
	if (InformClient) {
#ifndef STRICT_RFC
		/* Send statistics to client if registered as user: */
		if ((c != NULL) && (Client_Type(c) == CLIENT_USER)) {
			Conn_WriteStr( Idx,
			 ":%s NOTICE %s :%sConnection statistics: client %.1f kb, server %.1f kb.",
			 Client_ID(Client_ThisServer()), Client_ID(c),
			 NOTICE_TXTPREFIX,
			 (double)My_Connections[Idx].bytes_in / 1024,
			 (double)My_Connections[Idx].bytes_out / 1024);
		}
#endif
		/* Send ERROR to client (see RFC 2812, section 3.1.7) */
		if (FwdMsg)
			Conn_WriteStr(Idx, "ERROR :%s", FwdMsg);
		else
			Conn_WriteStr(Idx, "ERROR :Closing connection");
	}

	/* Try to write out the write buffer. Note: Handle_Write() eventually
	 * removes the CLIENT structure associated with this connection if an
	 * error occurs! So we have to re-check if there is still an valid
	 * CLIENT structure after calling Handle_Write() ...*/
	(void)Handle_Write( Idx );

	/* Search client, if any (re-check!) */
	c = Conn_GetClient( Idx );
#ifdef SSL_SUPPORT
	if ( Conn_OPTION_ISSET( &My_Connections[Idx], CONN_SSL )) {
		LogDebug("SSL connection %d shutting down ...", Idx);
		ConnSSL_Free(&My_Connections[Idx]);
	}
#endif
	/* Shut down socket */
	if (! io_close(My_Connections[Idx].sock)) {
		/* Oops, we can't close the socket!? This is ... ugly! */
		Log(LOG_CRIT,
		    "Error closing connection %d (socket %d) with %s:%d - %s! (ignored)",
		    Idx, My_Connections[Idx].sock, My_Connections[Idx].host,
		    port, strerror(errno));
	}

	/* Mark socket as invalid: */
	My_Connections[Idx].sock = NONE;

	/* If there is still a client, unregister it now */
	if (c)
		Client_Destroy(c, LogMsg, FwdMsg, true);

	/* Calculate statistics and log information */
	in_k = (double)My_Connections[Idx].bytes_in / 1024;
	out_k = (double)My_Connections[Idx].bytes_out / 1024;
#ifdef ZLIB
	if (Conn_OPTION_ISSET( &My_Connections[Idx], CONN_ZIP)) {
		in_z_k = (double)My_Connections[Idx].zip.bytes_in / 1024;
		out_z_k = (double)My_Connections[Idx].zip.bytes_out / 1024;
		/* Make sure that no division by zero can occur during
		 * the calculation of in_p and out_p: in_z_k and out_z_k
		 * are non-zero, that's guaranteed by the protocol until
		 * compression can be enabled. */
		if (in_z_k <= 0)
			in_z_k = in_k;
		if (out_z_k <= 0)
			out_z_k = out_k;
		in_p = (int)(( in_k * 100 ) / in_z_k );
		out_p = (int)(( out_k * 100 ) / out_z_k );
		Log(LOG_INFO,
		    "Connection %d with \"%s:%d\" closed (in: %.1fk/%.1fk/%d%%, out: %.1fk/%.1fk/%d%%).",
		    Idx, My_Connections[Idx].host, port,
		    in_k, in_z_k, in_p, out_k, out_z_k, out_p);
	}
	else
#endif
	{
		Log(LOG_INFO,
		    "Connection %d with \"%s:%d\" closed (in: %.1fk, out: %.1fk).",
		    Idx, My_Connections[Idx].host, port,
		    in_k, out_k);
	}

	/* Servers: Modify time of next connect attempt? */
	Conf_UnsetServer( Idx );

#ifdef ZLIB
	/* Clean up zlib, if link was compressed */
	if ( Conn_OPTION_ISSET( &My_Connections[Idx], CONN_ZIP )) {
		inflateEnd( &My_Connections[Idx].zip.in );
		deflateEnd( &My_Connections[Idx].zip.out );
		array_free(&My_Connections[Idx].zip.rbuf);
		array_free(&My_Connections[Idx].zip.wbuf);
	}
#endif

	array_free(&My_Connections[Idx].rbuf);
	array_free(&My_Connections[Idx].wbuf);
	if (My_Connections[Idx].pwd != NULL)
		free(My_Connections[Idx].pwd);

	/* Clean up connection structure (=free it) */
	Init_Conn_Struct( Idx );

	assert(NumConnections > 0);
	if (NumConnections)
		NumConnections--;
	LogDebug("Shutdown of connection %d completed, %ld connection%s left.",
		 Idx, NumConnections, NumConnections != 1 ? "s" : "");

	idle_t = NumConnections > 0 ? 0 : time(NULL);
} /* Conn_Close */

/**
 * Get current number of connections.
 *
 * @returns	Number of current connections.
 */
GLOBAL long
Conn_Count(void)
{
	return NumConnections;
} /* Conn_Count */

/**
 * Get number of maximum simultaneous connections.
 *
 * @returns	Number of maximum simultaneous connections.
 */
GLOBAL long
Conn_CountMax(void)
{
	return NumConnectionsMax;
} /* Conn_CountMax */

/**
 * Get number of connections accepted since the daemon startet.
 *
 * @returns	Number of connections accepted.
 */
GLOBAL long
Conn_CountAccepted(void)
{
	return NumConnectionsAccepted;
} /* Conn_CountAccepted */

/**
 * Synchronize established connections and configured server structures
 * after a configuration update and store the correct connection IDs, if any.
 */
GLOBAL void
Conn_SyncServerStruct(void)
{
	CLIENT *client;
	CONN_ID i;
	int c;

	for (i = 0; i < Pool_Size; i++) {
		if (My_Connections[i].sock == NONE)
			continue;

		/* Server link? */
		client = Conn_GetClient(i);
		if (!client || Client_Type(client) != CLIENT_SERVER)
			continue;

		for (c = 0; c < MAX_SERVERS; c++) {
			/* Configured server? */
			if (!Conf_Server[c].host[0])
				continue;

			if (strcasecmp(Conf_Server[c].name, Client_ID(client)) == 0)
				Conf_Server[c].conn_id = i;
		}
	}
} /* SyncServerStruct */

/**
 * Get IP address string of a connection.
 *
 * @param Idx Connection index.
 * @return Pointer to a global buffer containing the IP address as string.
 */
GLOBAL const char *
Conn_GetIPAInfo(CONN_ID Idx)
{
	assert(Idx > NONE);
	return ng_ipaddr_tostr(&My_Connections[Idx].addr);
}

/**
 * Send out data of write buffer; connect new sockets.
 *
 * @param Idx	Connection index.
 * @returns	true on success, false otherwise.
 */
static bool
Handle_Write( CONN_ID Idx )
{
	ssize_t len;
	size_t wdatalen;

	assert( Idx > NONE );
	if ( My_Connections[Idx].sock < 0 ) {
		LogDebug("Handle_Write() on closed socket, connection %d", Idx);
		return false;
	}
	assert( My_Connections[Idx].sock > NONE );

	wdatalen = array_bytes(&My_Connections[Idx].wbuf );

#ifdef ZLIB
	if (wdatalen == 0) {
		/* Write buffer is empty, so we try to flush the compression
		 * buffer and get some data to work with from there :-) */
		if (!Zip_Flush(Idx))
			return false;

		/* Now the write buffer most probably has changed: */
		wdatalen = array_bytes(&My_Connections[Idx].wbuf);
	}
#endif

	if (wdatalen == 0) {
		/* Still no data, fine. */
		io_event_del(My_Connections[Idx].sock, IO_WANTWRITE );
		return true;
	}

#if DEBUG_BUFFER
	LogDebug
	    ("Handle_Write() called for connection %d, %ld bytes pending ...",
	     Idx, wdatalen);
#endif

#ifdef SSL_SUPPORT
	if ( Conn_OPTION_ISSET( &My_Connections[Idx], CONN_SSL )) {
		len = ConnSSL_Write(&My_Connections[Idx],
				    array_start(&My_Connections[Idx].wbuf),
				    wdatalen);
	} else
#endif
	{
		len = write(My_Connections[Idx].sock,
			    array_start(&My_Connections[Idx].wbuf), wdatalen );
	}
	if( len < 0 ) {
		if (errno == EAGAIN || errno == EINTR)
			return true;

		/* Log write errors but do not close the connection yet.
		 * Calling Conn_Close() now could result in too many recursive calls.
		 */
		if (!Conn_OPTION_ISSET(&My_Connections[Idx], CONN_ISCLOSING))
			Log(LOG_ERR,
			    "Write error on connection %d (socket %d): %s!",
			    Idx, My_Connections[Idx].sock, strerror(errno));
		else
			LogDebug("Recursive write error on connection %d (socket %d): %s!",
				 Idx, My_Connections[Idx].sock, strerror(errno));

		return false;
	}

	/* move any data not yet written to beginning */
	array_moveleft(&My_Connections[Idx].wbuf, 1, (size_t)len);

	return true;
} /* Handle_Write */

/**
 * Count established connections to a specific IP address.
 *
 * @returns	Number of established connections.
 */
static int
Count_Connections(ng_ipaddr_t *a)
{
	int i, cnt;

	cnt = 0;
	for (i = 0; i < Pool_Size; i++) {
		if (My_Connections[i].sock <= NONE)
			continue;
		if (ng_ipaddr_ipequal(&My_Connections[i].addr, a))
			cnt++;
	}
	return cnt;
} /* Count_Connections */

/**
 * Initialize new client connection on a listening socket.
 *
 * @param Sock	Listening socket descriptor.
 * @param IsSSL	true if this socket expects SSL-encrypted data.
 * @returns	Accepted socket descriptor or -1 on error.
 */
static int
New_Connection(int Sock, UNUSED bool IsSSL)
{
#ifdef TCPWRAP
	struct request_info req;
#endif
	ng_ipaddr_t new_addr;
	char ip_str[NG_INET_ADDRSTRLEN];
	int new_sock, new_sock_len;
	CLIENT *c;
	long cnt;

	assert(Sock > NONE);

	LogDebug("Accepting new connection on socket %d ...", Sock);

	new_sock_len = (int)sizeof(new_addr);
	new_sock = accept(Sock, (struct sockaddr *)&new_addr,
			  (socklen_t *)&new_sock_len);
	if (new_sock < 0) {
		Log(LOG_CRIT, "Can't accept connection: %s!", strerror(errno));
		return -1;
	}
	NumConnectionsAccepted++;

	if (!ng_ipaddr_tostr_r(&new_addr, ip_str)) {
		Log(LOG_CRIT, "fd %d: Can't convert IP address!", new_sock);
		Simple_Message(new_sock, "ERROR :Internal Server Error");
		close(new_sock);
		return -1;
	}

#ifdef TCPWRAP
	/* Validate socket using TCP Wrappers */
	request_init(&req, RQ_DAEMON, PACKAGE_NAME, RQ_FILE, new_sock,
		     RQ_CLIENT_SIN, &new_addr, NULL);
	fromhost(&req);
	if (!hosts_access(&req)) {
		Log(deny_severity,
		    "Refused connection from %s (by TCP Wrappers)!", ip_str);
		Simple_Message(new_sock, "ERROR :Connection refused");
		close(new_sock);
		return -1;
	}
#endif

	if (!Init_Socket(new_sock))
		return -1;

	/* Check global connection limit */
	if ((Conf_MaxConnections > 0) &&
	    (NumConnections >= (size_t) Conf_MaxConnections)) {
		Log(LOG_ALERT, "Can't accept new connection on socket %d: Limit (%d) reached!",
		    Sock, Conf_MaxConnections);
		Simple_Message(new_sock, "ERROR :Connection limit reached");
		close(new_sock);
		return -1;
	}

	/* Check IP-based connection limit */
	cnt = Count_Connections(&new_addr);
	if ((Conf_MaxConnectionsIP > 0) && (cnt >= Conf_MaxConnectionsIP)) {
		/* Access denied, too many connections from this IP address! */
		Log(LOG_ERR,
		    "Refused connection from %s: too may connections (%ld) from this IP address!",
		    ip_str, cnt);
		Simple_Message(new_sock,
			       "ERROR :Connection refused, too many connections from your IP address");
		close(new_sock);
		return -1;
	}

	if (Socket2Index(new_sock) <= NONE) {
		Simple_Message(new_sock, "ERROR: Internal error");
		close(new_sock);
		return -1;
	}

	/* register callback */
	if (!io_event_create(new_sock, IO_WANTREAD, cb_clientserver)) {
		Log(LOG_ALERT,
		    "Can't accept connection: io_event_create failed!");
		Simple_Message(new_sock, "ERROR :Internal error");
		close(new_sock);
		return -1;
	}

	c = Client_NewLocal(new_sock, NULL, CLIENT_UNKNOWN, false);
	if (!c) {
		Log(LOG_ALERT,
		    "Can't accept connection: can't create client structure!");
		Simple_Message(new_sock, "ERROR :Internal error");
		io_close(new_sock);
		return -1;
	}

	Init_Conn_Struct(new_sock);
	My_Connections[new_sock].sock = new_sock;
	My_Connections[new_sock].addr = new_addr;
	My_Connections[new_sock].client = c;

	/* Set initial hostname to IP address. This becomes overwritten when
	 * the DNS lookup is enabled and succeeds, but is used otherwise. */
	if (ng_ipaddr_af(&new_addr) != AF_INET)
		snprintf(My_Connections[new_sock].host,
			 sizeof(My_Connections[new_sock].host), "[%s]", ip_str);
	else
		strlcpy(My_Connections[new_sock].host, ip_str,
			sizeof(My_Connections[new_sock].host));

	Client_SetHostname(c, My_Connections[new_sock].host);

	Log(LOG_INFO, "Accepted connection %d from \"%s:%d\" on socket %d.",
	    new_sock, My_Connections[new_sock].host,
	    ng_ipaddr_getport(&new_addr), Sock);
	Account_Connection();

#ifdef SSL_SUPPORT
	/* Delay connection initalization until SSL handshake is finished */
	if (!IsSSL)
#endif
		Conn_StartLogin(new_sock);

	return new_sock;
} /* New_Connection */

/**
 * Finish connection initialization, start resolver subprocess.
 *
 * @param Idx Connection index.
 */
GLOBAL void
Conn_StartLogin(CONN_ID Idx)
{
	int ident_sock = -1;

	assert(Idx >= 0);

	/* Nothing to do if DNS (and resolver subprocess) is disabled */
	if (!Conf_DNS)
		return;

#ifdef IDENTAUTH
	/* Should we make an IDENT request? */
	if (Conf_Ident)
		ident_sock = My_Connections[Idx].sock;
#endif

	if (Conf_NoticeBeforeRegistration) {
		/* Send "NOTICE *" messages to the client */
#ifdef IDENTAUTH
		if (Conf_Ident)
			(void)Conn_WriteStr(Idx,
				"NOTICE * :*** Looking up your hostname and checking ident");
		else
#endif
			(void)Conn_WriteStr(Idx,
				"NOTICE * :*** Looking up your hostname");
		/* Send buffered data to the client, but break on errors
		 * because Handle_Write() would have closed the connection
		 * again in this case! */
		if (!Handle_Write(Idx))
			return;
	}

	Resolve_Addr(&My_Connections[Idx].proc_stat, &My_Connections[Idx].addr,
		     ident_sock, cb_Read_Resolver_Result);
}

/**
 * Update global connection counters.
 */
static void
Account_Connection(void)
{
	NumConnections++;
	idle_t = 0;
	if (NumConnections > NumConnectionsMax)
		NumConnectionsMax = NumConnections;
	LogDebug("Total number of connections now %lu (max %lu).",
		 NumConnections, NumConnectionsMax);
} /* Account_Connection */

/**
 * Translate socket handle into connection index (for historical reasons, it is
 * a 1:1 mapping today) and enlarge the "connection pool" accordingly.
 *
 * @param Sock	Socket handle.
 * @returns	Connecion index or NONE when the pool is too small.
 */
static CONN_ID
Socket2Index( int Sock )
{
	assert(Sock > 0);
	assert(Pool_Size >= 0);

	if (Sock < Pool_Size)
		return Sock;

	/* Try to allocate more memory ... */
	if (!array_alloc(&My_ConnArray, sizeof(CONNECTION), (size_t)Sock)) {
		Log(LOG_EMERG,
		    "Can't allocate memory to enlarge connection pool!");
		return NONE;
	}
	LogDebug("Enlarged connection pool for %ld sockets (%ld items, %ld bytes)",
		 Sock, array_length(&My_ConnArray, sizeof(CONNECTION)),
		 array_bytes(&My_ConnArray));

	/* Adjust pointer to new block, update size and initialize new items. */
	My_Connections = array_start(&My_ConnArray);
	while (Pool_Size <= Sock)
		Init_Conn_Struct(Pool_Size++);

	return Sock;
}

/**
 * Read data from the network to the read buffer. If an error occurs,
 * the socket of this connection will be shut down.
 *
 * @param Idx	Connection index.
 */
static void
Read_Request(CONN_ID Idx)
{
	ssize_t len;
	static const unsigned int maxbps = COMMAND_LEN / 2;
	char readbuf[READBUFFER_LEN];
	time_t t;
	CLIENT *c;

	assert(Idx > NONE);
	assert(My_Connections[Idx].sock > NONE);

	/* Check if the read buffer is "full". Basically this shouldn't happen
	 * here, because as long as there possibly are commands in the read
	 * buffer (buffer usage > COMMAND_LEN), the socket shouldn't be
	 * scheduled for reading in Conn_Handler() at all ... */
#ifdef ZLIB
	if ((array_bytes(&My_Connections[Idx].rbuf) >= READBUFFER_LEN) ||
		(array_bytes(&My_Connections[Idx].zip.rbuf) >= READBUFFER_LEN))
#else
	if (array_bytes(&My_Connections[Idx].rbuf) >= READBUFFER_LEN)
#endif
	{
		Log(LOG_ERR,
		    "Receive buffer space exhausted (connection %d): %d/%d bytes",
		    Idx, array_bytes(&My_Connections[Idx].rbuf), READBUFFER_LEN);
		Conn_Close(Idx, "Receive buffer space exhausted", NULL, false);
		return;
	}

	/* Now read new data from the network, up to READBUFFER_LEN bytes ... */
#ifdef SSL_SUPPORT
	if (Conn_OPTION_ISSET(&My_Connections[Idx], CONN_SSL))
		len = ConnSSL_Read(&My_Connections[Idx], readbuf, sizeof(readbuf));
	else
#endif
		len = read(My_Connections[Idx].sock, readbuf, sizeof(readbuf));

	if (len == 0) {
		LogDebug("Client \"%s:%u\" is closing connection %d ...",
			 My_Connections[Idx].host,
			 ng_ipaddr_getport(&My_Connections[Idx].addr), Idx);
		Conn_Close(Idx, NULL, "Client closed connection", false);
		return;
	}

	if (len < 0) {
		if (errno == EAGAIN)
			return;

		Log(LOG_ERR, "Read error on connection %d (socket %d): %s!",
		    Idx, My_Connections[Idx].sock, strerror(errno));
		Conn_Close(Idx, "Read error", "Client closed connection",
			   false);
		return;
	}

	/* Now append the newly received data to the connection buffer.
	 * NOTE: This can lead to connection read buffers being bigger(!) than
	 * READBUFFER_LEN bytes, as we add up to READBUFFER_LEN new bytes to a
	 * buffer possibly being "almost" READBUFFER_LEN bytes already! */
#ifdef ZLIB
	if (Conn_OPTION_ISSET(&My_Connections[Idx], CONN_ZIP)) {
		if (!array_catb(&My_Connections[Idx].zip.rbuf, readbuf,
				(size_t) len)) {
			Log(LOG_ERR,
			    "Could not append received data to zip input buffer (connection %d): %d bytes!",
			    Idx, len);
			Conn_Close(Idx, "Receive buffer space exhausted", NULL,
				   false);
			return;
		}
	} else
#endif
	{
		if (!array_catb( &My_Connections[Idx].rbuf, readbuf, len)) {
			Log(LOG_ERR,
			    "Could not append received data to input buffer (connection %d): %d bytes!",
			    Idx, len);
			Conn_Close(Idx, "Receive buffer space exhausted", NULL,
				   false );
		}
	}

	/* Update connection statistics */
	My_Connections[Idx].bytes_in += len;

	/* Handle read buffer */
	My_Connections[Idx].bps += Handle_Buffer(Idx);

	/* Make sure that there is still a valid client registered */
	c = Conn_GetClient(Idx);
	if (!c)
		return;

	/* Update timestamp of last data received if this connection is
	 * registered as a user, server or service connection. Don't update
	 * otherwise, so users have at least Conf_PongTimeout seconds time to
	 * register with the IRC server -- see Check_Connections().
	 * Update "lastping", too, if time shifted backwards ... */
	if (Client_Type(c) == CLIENT_USER
	    || Client_Type(c) == CLIENT_SERVER
	    || Client_Type(c) == CLIENT_SERVICE) {
		t = time(NULL);
		if (My_Connections[Idx].lastdata != t)
			My_Connections[Idx].bps = 0;

		My_Connections[Idx].lastdata = t;
		if (My_Connections[Idx].lastping > t)
			My_Connections[Idx].lastping = t;
	}

	/* Look at the data in the (read-) buffer of this connection */
	if (My_Connections[Idx].bps >= maxbps)
		Throttle_Connection(Idx, c, THROTTLE_BPS, maxbps);
} /* Read_Request */

/**
 * Handle all data in the connection read-buffer.
 *
 * Data is processed until no complete command is left in the read buffer,
 * or MAX_COMMANDS[_SERVER|_SERVICE] commands were processed.
 * When a fatal error occurs, the connection is shut down.
 *
 * @param Idx	Index of the connection.
 * @returns	Number of bytes processed.
 */
static unsigned int
Handle_Buffer(CONN_ID Idx)
{
#ifndef STRICT_RFC
	char *ptr1, *ptr2, *first_eol;
#endif
	char *ptr;
	size_t len, delta;
	time_t starttime;
#ifdef ZLIB
	bool old_z;
#endif
	unsigned int i, maxcmd = MAX_COMMANDS, len_processed = 0;
	CLIENT *c;

	c = Conn_GetClient(Idx);
	starttime = time(NULL);

	assert(c != NULL);

	/* Servers get special command limits that depend on the user count */
	switch (Client_Type(c)) {
	    case CLIENT_SERVER:
		maxcmd = (int)(Client_UserCount() / 5)
		       + MAX_COMMANDS_SERVER_MIN;
		/* Allow servers to handle even more commands while peering
		 * to speed up server login and network synchronization. */
		if (Conn_LastPing(Idx) == 0)
			maxcmd *= 5;
		break;
	    case CLIENT_SERVICE:
		maxcmd = MAX_COMMANDS_SERVICE;
		break;
	    case CLIENT_USER:
		if (Client_HasMode(c, 'F'))
			maxcmd = MAX_COMMANDS_SERVICE;
		break;
	}

	for (i=0; i < maxcmd; i++) {
		/* Check penalty */
		if (My_Connections[Idx].delaytime > starttime)
			return 0;
#ifdef ZLIB
		/* Unpack compressed data, if compression is in use */
		if (Conn_OPTION_ISSET(&My_Connections[Idx], CONN_ZIP)) {
			/* When unzipping fails, Unzip_Buffer() shuts
			 * down the connection itself */
			if (!Unzip_Buffer(Idx))
				return 0;
		}
#endif

		if (0 == array_bytes(&My_Connections[Idx].rbuf))
			break;

		/* Make sure that the buffer is NULL terminated */
		if (!array_cat0_temporary(&My_Connections[Idx].rbuf)) {
			Conn_Close(Idx, NULL,
				   "Can't allocate memory [Handle_Buffer]",
				   true);
			return 0;
		}

		/* RFC 2812, section "2.3 Messages", 5th paragraph:
		 * "IRC messages are always lines of characters terminated
		 * with a CR-LF (Carriage Return - Line Feed) pair [...]". */
		delta = 2;
		ptr = strstr(array_start(&My_Connections[Idx].rbuf), "\r\n");

#ifndef STRICT_RFC
		/* Check for non-RFC-compliant request (only CR or LF)?
		 * Unfortunately, there are quite a few clients out there
		 * that do this -- e. g. mIRC, BitchX, and Trillian :-( */
		ptr1 = strchr(array_start(&My_Connections[Idx].rbuf), '\r');
		ptr2 = strchr(array_start(&My_Connections[Idx].rbuf), '\n');
		if (ptr) {
			/* Check if there is a single CR or LF _before_ the
			 * correct CR+LF line terminator:  */
			first_eol = ptr1 < ptr2 ? ptr1 : ptr2;
			if (first_eol < ptr) {
				/* Single CR or LF before CR+LF found */
				ptr = first_eol;
				delta = 1;
			}
		} else if (ptr1 || ptr2) {
			/* No CR+LF terminated command found, but single
			 * CR or LF found ... */
			if (ptr1 && ptr2)
				ptr = ptr1 < ptr2 ? ptr1 : ptr2;
			else
				ptr = ptr1 ? ptr1 : ptr2;
			delta = 1;
		}
#endif

		if (!ptr)
			break;

		/* Complete (=line terminated) request found, handle it! */
		*ptr = '\0';

		len = ptr - (char *)array_start(&My_Connections[Idx].rbuf) + delta;

		if (len > (COMMAND_LEN - 1)) {
			/* Request must not exceed 512 chars (incl. CR+LF!),
			 * see RFC 2812. Disconnect Client if this happens. */
			Log(LOG_ERR,
			    "Request too long (connection %d): %d bytes (max. %d expected)!",
			    Idx, array_bytes(&My_Connections[Idx].rbuf),
			    COMMAND_LEN - 1);
			Conn_Close(Idx, NULL, "Request too long", true);
			return 0;
		}

		len_processed += (unsigned int)len;
		if (len <= delta) {
			/* Request is empty (only '\r\n', '\r' or '\n');
			 * delta is 2 ('\r\n') or 1 ('\r' or '\n'), see above */
			array_moveleft(&My_Connections[Idx].rbuf, 1, len);
			continue;
		}
#ifdef ZLIB
		/* remember if stream is already compressed */
		old_z = My_Connections[Idx].options & CONN_ZIP;
#endif

		My_Connections[Idx].msg_in++;
		if (!Parse_Request
		    (Idx, (char *)array_start(&My_Connections[Idx].rbuf)))
			return 0; /* error -> connection has been closed */

		array_moveleft(&My_Connections[Idx].rbuf, 1, len);
#ifdef ZLIB
		if ((!old_z) && (My_Connections[Idx].options & CONN_ZIP) &&
		    (array_bytes(&My_Connections[Idx].rbuf) > 0)) {
			/* The last command activated socket compression.
			 * Data that was read after that needs to be copied
			 * to the unzip buffer for decompression: */
			if (!array_copy
			    (&My_Connections[Idx].zip.rbuf,
			     &My_Connections[Idx].rbuf)) {
				Conn_Close(Idx, NULL,
					   "Can't allocate memory [Handle_Buffer]",
					   true);
				return 0;
			}

			array_trunc(&My_Connections[Idx].rbuf);
			LogDebug
			    ("Moved already received data (%u bytes) to uncompression buffer.",
			     array_bytes(&My_Connections[Idx].zip.rbuf));
		}
#endif
	}
#if DEBUG_BUFFER
	LogDebug("Connection %d: Processed %ld commands (max=%ld), %ld bytes. %ld bytes left in read buffer.",
		 Idx, i, maxcmd, len_processed,
		 array_bytes(&My_Connections[Idx].rbuf));
#endif

	/* If data has been processed but there is still data in the read
	 * buffer, the command limit triggered. Enforce the penalty time: */
	if (len_processed && array_bytes(&My_Connections[Idx].rbuf) > 2)
		Throttle_Connection(Idx, c, THROTTLE_CMDS, maxcmd);

	return len_processed;
} /* Handle_Buffer */

/**
 * Check whether established connections are still alive or not.
 * If not, play PING-PONG first; and if that doesn't help either,
 * disconnect the respective peer.
 */
static void
Check_Connections(void)
{
	CLIENT *c;
	CONN_ID i;
	char msg[64];
	time_t time_now;

	time_now = time(NULL);

	for (i = 0; i < Pool_Size; i++) {
		if (My_Connections[i].sock < 0)
			continue;

		c = Conn_GetClient(i);
		if (c && ((Client_Type(c) == CLIENT_USER)
			  || (Client_Type(c) == CLIENT_SERVER)
			  || (Client_Type(c) == CLIENT_SERVICE))) {
			/* connected User, Server or Service */
			if (My_Connections[i].lastping >
			    My_Connections[i].lastdata) {
				/* We already sent a ping */
				if (My_Connections[i].lastping <
				    time_now - Conf_PongTimeout) {
					/* Timeout */
					snprintf(msg, sizeof(msg),
						 "Ping timeout: %d seconds",
						 Conf_PongTimeout);
					LogDebug("Connection %d: %s.", i, msg);
					Conn_Close(i, NULL, msg, true);
				}
			} else if (My_Connections[i].lastdata <
				   time_now - Conf_PingTimeout) {
				/* We need to send a PING ... */
				LogDebug("Connection %d: sending PING ...", i);
				Conn_UpdatePing(i, time_now);
				Conn_WriteStr(i, "PING :%s",
					      Client_ID(Client_ThisServer()));
			}
		} else {
			/* The connection is not fully established yet, so
			 * we don't do the PING-PONG game here but instead
			 * disconnect the client after "a short time" if it's
			 * still not registered. */

			if (My_Connections[i].lastdata <
			    time_now - Conf_PongTimeout) {
				LogDebug
				    ("Unregistered connection %d timed out ...",
				     i);
				Conn_Close(i, NULL, "Timeout", false);
			}
		}
	}
} /* Check_Connections */

/**
 * Check if further server links should be established.
 */
static void
Check_Servers(void)
{
	int i, n;
	time_t time_now;

	time_now = time(NULL);

	/* Check all configured servers */
	for (i = 0; i < MAX_SERVERS; i++) {
		if (Conf_Server[i].conn_id != NONE)
			continue;	/* Already establishing or connected */
		if (!Conf_Server[i].host[0] || Conf_Server[i].port <= 0)
			continue;	/* No host and/or port configured */
		if (Conf_Server[i].flags & CONF_SFLAG_DISABLED)
			continue;	/* Disabled configuration entry */
		if (Conf_Server[i].lasttry > (time_now - Conf_ConnectRetry))
			continue;	/* We have to wait a little bit ... */

		/* Is there already a connection in this group? */
		if (Conf_Server[i].group > NONE) {
			for (n = 0; n < MAX_SERVERS; n++) {
				if (n == i)
					continue;
				if ((Conf_Server[n].conn_id != NONE) &&
				    (Conf_Server[n].group == Conf_Server[i].group))
					break;
			}
			if (n < MAX_SERVERS)
				continue;
		}

		/* Okay, try to connect now */
		Log(LOG_NOTICE,
		    "Preparing to establish a new server link for \"%s\" ...",
		    Conf_Server[i].name);
		Conf_Server[i].lasttry = time_now;
		Conf_Server[i].conn_id = SERVER_WAIT;
		assert(Proc_GetPipeFd(&Conf_Server[i].res_stat) < 0);

		/* Start resolver subprocess ... */
		if (!Resolve_Name(&Conf_Server[i].res_stat, Conf_Server[i].host,
				  cb_Connect_to_Server))
			Conf_Server[i].conn_id = NONE;
	}
} /* Check_Servers */

/**
 * Establish a new outgoing server connection.
 *
 * @param Server	Configuration index of the server.
 * @param dest		Destination IP address to connect to.
 */
static void
New_Server( int Server , ng_ipaddr_t *dest)
{
	/* Establish new server link */
	char ip_str[NG_INET_ADDRSTRLEN];
	int af_dest, res, new_sock;
	CLIENT *c;

	assert( Server > NONE );

	/* Make sure that the remote server hasn't re-linked to this server
	 * asynchronously on its own */
	if (Conf_Server[Server].conn_id > NONE) {
		Log(LOG_INFO,
			"Connection to \"%s\" meanwhile re-established, aborting preparation.");
		return;
	}

	if (!ng_ipaddr_tostr_r(dest, ip_str)) {
		Log(LOG_WARNING, "New_Server: Could not convert IP to string");
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	af_dest = ng_ipaddr_af(dest);
	new_sock = socket(af_dest, SOCK_STREAM, 0);

	Log(LOG_INFO,
	    "Establishing connection for \"%s\" to \"%s:%d\" (%s), socket %d ...",
	    Conf_Server[Server].name, Conf_Server[Server].host,
	    Conf_Server[Server].port, ip_str, new_sock);

	if (new_sock < 0) {
		Log(LOG_CRIT, "Can't create socket (af %d): %s!",
		    af_dest, strerror(errno));
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	if (!Init_Socket(new_sock)) {
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	/* is a bind address configured? */
	res = ng_ipaddr_af(&Conf_Server[Server].bind_addr);

	/* if yes, bind now. If it fails, warn and let connect() pick a
	 * source address */
	if (res && bind(new_sock, (struct sockaddr *) &Conf_Server[Server].bind_addr,
				ng_ipaddr_salen(&Conf_Server[Server].bind_addr)))
	{
		ng_ipaddr_tostr_r(&Conf_Server[Server].bind_addr, ip_str);
		Log(LOG_WARNING, "Can't bind socket to %s: %s!", ip_str,
		    strerror(errno));
	}
	ng_ipaddr_setport(dest, Conf_Server[Server].port);
	res = connect(new_sock, (struct sockaddr *) dest, ng_ipaddr_salen(dest));
	if(( res != 0 ) && ( errno != EINPROGRESS )) {
		Log( LOG_CRIT, "Can't connect socket: %s!", strerror( errno ));
		close( new_sock );
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	if (Socket2Index(new_sock) <= NONE) {
		close( new_sock );
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	if (!io_event_create( new_sock, IO_WANTWRITE, cb_connserver)) {
		Log(LOG_ALERT, "io_event_create(): could not add fd %d",
		    strerror(errno));
		close(new_sock);
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	assert(My_Connections[new_sock].sock <= 0);

	Init_Conn_Struct(new_sock);

	ng_ipaddr_tostr_r(dest, ip_str);
	c = Client_NewLocal(new_sock, ip_str, CLIENT_UNKNOWNSERVER, false);
	if (!c) {
		Log( LOG_ALERT, "Can't establish connection: can't create client structure!" );
		io_close(new_sock);
		Conf_Server[Server].conn_id = NONE;
		return;
	}

	/* Conn_Close() decrements this counter again */
	Account_Connection();
	Client_SetIntroducer( c, c );
	Client_SetToken( c, TOKEN_OUTBOUND );

	/* Register connection */
	if (!Conf_SetServer(Server, new_sock))
		return;
	My_Connections[new_sock].sock = new_sock;
	My_Connections[new_sock].addr = *dest;
	My_Connections[new_sock].client = c;
	strlcpy( My_Connections[new_sock].host, Conf_Server[Server].host,
				sizeof(My_Connections[new_sock].host ));

#ifdef SSL_SUPPORT
	if (Conf_Server[Server].SSLConnect &&
	    !ConnSSL_PrepareConnect(&My_Connections[new_sock], &Conf_Server[Server]))
	{
		Log(LOG_ALERT, "Could not initialize SSL for outgoing connection");
		Conn_Close(new_sock, "Could not initialize SSL for outgoing connection",
			   NULL, false);
		Init_Conn_Struct(new_sock);
		Conf_Server[Server].conn_id = NONE;
		return;
	}
#endif
	LogDebug("Registered new connection %d on socket %d (%ld in total).",
		 new_sock, My_Connections[new_sock].sock, NumConnections);
	Conn_OPTION_ADD( &My_Connections[new_sock], CONN_ISCONNECTING );
} /* New_Server */

/**
 * Initialize connection structure.
 *
 * @param Idx	Connection index.
 */
static void
Init_Conn_Struct(CONN_ID Idx)
{
	time_t now = time(NULL);

	memset(&My_Connections[Idx], 0, sizeof(CONNECTION));
	My_Connections[Idx].sock = -1;
	My_Connections[Idx].signon = now;
	My_Connections[Idx].lastdata = now;
	My_Connections[Idx].lastprivmsg = now;
	Proc_InitStruct(&My_Connections[Idx].proc_stat);

#ifdef ICONV
	My_Connections[Idx].iconv_from = (iconv_t)(-1);
	My_Connections[Idx].iconv_to = (iconv_t)(-1);
#endif
} /* Init_Conn_Struct */

/**
 * Initialize options of a new socket.
 *
 * For example, we try to set socket options SO_REUSEADDR and IPTOS_LOWDELAY.
 * The socket is automatically closed if a fatal error is encountered.
 *
 * @param Sock	Socket handle.
 * @returns false if socket was closed due to fatal error.
 */
static bool
Init_Socket( int Sock )
{
	int value;

	if (!io_setnonblock(Sock)) {
		Log(LOG_CRIT, "Can't enable non-blocking mode for socket: %s!",
		    strerror(errno));
		close(Sock);
		return false;
	}

	/* Don't block this port after socket shutdown */
	value = 1;
	if (setsockopt(Sock, SOL_SOCKET, SO_REUSEADDR, &value,
		       (socklen_t)sizeof(value)) != 0) {
		Log(LOG_ERR, "Can't set socket option SO_REUSEADDR: %s!",
		    strerror(errno));
		/* ignore this error */
	}

	/* Set type of service (TOS) */
#if defined(IPPROTO_IP) && defined(IPTOS_LOWDELAY)
	value = IPTOS_LOWDELAY;
	if (setsockopt(Sock, IPPROTO_IP, IP_TOS, &value,
		       (socklen_t) sizeof(value))) {
		LogDebug("Can't set socket option IP_TOS: %s!",
			 strerror(errno));
		/* ignore this error */
	} else
		LogDebug("IP_TOS on socket %d has been set to IPTOS_LOWDELAY.",
			 Sock);
#endif

	return true;
} /* Init_Socket */

/**
 * Read results of a resolver sub-process and try to initiate a new server
 * connection.
 *
 * @param fd		File descriptor of the pipe to the sub-process.
 * @param events	(ignored IO specification)
 */
static void
cb_Connect_to_Server(int fd, UNUSED short events)
{
	int i;
	size_t len;

	/* we can handle at most 3 addresses; but we read up to 4 so we can
	 * log the 'more than we can handle' condition. First result is tried
	 * immediately, rest is saved for later if needed. */
	ng_ipaddr_t dest_addrs[4];

	LogDebug("Resolver: Got forward lookup callback on fd %d, events %d",
		 fd, events);

	for (i=0; i < MAX_SERVERS; i++) {
		  if (Proc_GetPipeFd(&Conf_Server[i].res_stat) == fd )
			  break;
	}

	if( i >= MAX_SERVERS) {
		/* Ops, no matching server found?! */
		io_close( fd );
		LogDebug("Resolver: Got Forward Lookup callback for unknown server!?");
		return;
	}

	/* Read result from pipe */
	len = Proc_Read(&Conf_Server[i].res_stat, dest_addrs, sizeof(dest_addrs));
	Proc_Close(&Conf_Server[i].res_stat);
	if (len == 0) {
		/* Error resolving hostname: reset server structure */
		Conf_Server[i].conn_id = NONE;
		return;
	}

	assert((len % sizeof(ng_ipaddr_t)) == 0);

	LogDebug("Got result from resolver: %u structs (%u bytes).",
		 len/sizeof(ng_ipaddr_t), len);

	memset(&Conf_Server[i].dst_addr, 0, sizeof(Conf_Server[i].dst_addr));
	if (len > sizeof(ng_ipaddr_t)) {
		/* more than one address for this hostname, remember them
		 * in case first address is unreachable/not available */
		len -= sizeof(ng_ipaddr_t);
		if (len > sizeof(Conf_Server[i].dst_addr)) {
			len = sizeof(Conf_Server[i].dst_addr);
			Log(LOG_NOTICE,
				"Notice: Resolver returned more IP Addresses for host than we can handle, additional addresses dropped.");
		}
		memcpy(&Conf_Server[i].dst_addr, &dest_addrs[1], len);
	}
	/* connect() */
	New_Server(i, dest_addrs);
} /* cb_Read_Forward_Lookup */

/**
 * Read results of a resolver sub-process from the pipe and update the
 * appropriate connection/client structure(s): hostname and/or IDENT user name.
 *
 * @param r_fd		File descriptor of the pipe to the sub-process.
 * @param events	(ignored IO specification)
 */
static void
cb_Read_Resolver_Result( int r_fd, UNUSED short events )
{
	CLIENT *c;
	CONN_ID i;
	size_t len;
	char *identptr;
#ifdef IDENTAUTH
	char readbuf[HOST_LEN + 2 + CLIENT_USER_LEN];
	char *ptr;
#else
	char readbuf[HOST_LEN + 1];
#endif

	LogDebug("Resolver: Got callback on fd %d, events %d", r_fd, events );
	i = Conn_GetFromProc(r_fd);
	if (i == NONE) {
		/* Ops, none found? Probably the connection has already
		 * been closed!? We'll ignore that ... */
		io_close( r_fd );
		LogDebug("Resolver: Got callback for unknown connection!?");
		return;
	}

	/* Read result from pipe */
	len = Proc_Read(&My_Connections[i].proc_stat, readbuf, sizeof readbuf -1);
	Proc_Close(&My_Connections[i].proc_stat);
	if (len == 0)
		return;

	readbuf[len] = '\0';
	identptr = strchr(readbuf, '\n');
	assert(identptr != NULL);
	if (!identptr) {
		Log( LOG_CRIT, "Resolver: Got malformed result!");
		return;
	}

	*identptr = '\0';
	LogDebug("Got result from resolver: \"%s\" (%u bytes read).", readbuf, len);
	/* Okay, we got a complete result: this is a host name for outgoing
	 * connections and a host name and IDENT user name (if enabled) for
	 * incoming connections.*/
	assert ( My_Connections[i].sock >= 0 );
	/* Incoming connection. Search client ... */
	c = Conn_GetClient( i );
	assert( c != NULL );

	/* Only update client information of unregistered clients.
	 * Note: user commands (e. g. WEBIRC) are always read _after_ reading
	 * the resolver results, so we don't have to worry to override settings
	 * from these commands here. */
	if(Client_Type(c) == CLIENT_UNKNOWN) {
		strlcpy(My_Connections[i].host, readbuf,
			sizeof(My_Connections[i].host));
		Client_SetHostname(c, readbuf);
		if (Conf_NoticeBeforeRegistration)
			(void)Conn_WriteStr(i,
					"NOTICE * :*** Found your hostname: %s",
					My_Connections[i].host);
#ifdef IDENTAUTH
		++identptr;
		if (*identptr) {
			ptr = identptr;
			while (*ptr) {
				if ((*ptr < '0' || *ptr > '9') &&
				    (*ptr < 'A' || *ptr > 'Z') &&
				    (*ptr < 'a' || *ptr > 'z'))
					break;
				ptr++;
			}
			if (*ptr) {
				/* Erroneous IDENT reply */
				Log(LOG_NOTICE,
				    "Got invalid IDENT reply for connection %d! Ignored.",
				    i);
			} else {
				Log(LOG_INFO,
				    "IDENT lookup for connection %d: \"%s\".",
				    i, identptr);
				Client_SetUser(c, identptr, true);
			}
			if (Conf_NoticeBeforeRegistration) {
				(void)Conn_WriteStr(i,
					"NOTICE * :*** Got %sident response%s%s",
					*ptr ? "invalid " : "",
					*ptr ? "" : ": ",
					*ptr ? "" : identptr);
			}
		} else if(Conf_Ident) {
			Log(LOG_INFO, "IDENT lookup for connection %d: no result.", i);
			if (Conf_NoticeBeforeRegistration)
				(void)Conn_WriteStr(i,
					"NOTICE * :*** No ident response");
		}
#endif

		if (Conf_NoticeBeforeRegistration) {
			/* Send buffered data to the client, but break on
			 * errors because Handle_Write() would have closed
			 * the connection again in this case! */
			if (!Handle_Write(i))
				return;
		}

		Class_HandleServerBans(c);
	}
#ifdef DEBUG
	else
		LogDebug("Resolver: discarding result for already registered connection %d.", i);
#endif
} /* cb_Read_Resolver_Result */

/**
 * Write a "simple" (error) message to a socket.
 *
 * The message is sent without using the connection write buffers, without
 * compression/encryption, and even without any error reporting. It is
 * designed for error messages of e.g. New_Connection().
 *
 * @param Sock	Socket handle.
 * @param Msg	Message string to send.
 */
static void
Simple_Message(int Sock, const char *Msg)
{
	char buf[COMMAND_LEN];
	size_t len;

	assert(Sock > NONE);
	assert(Msg != NULL);

	strlcpy(buf, Msg, sizeof buf - 2);
	len = strlcat(buf, "\r\n", sizeof buf);
	if (write(Sock, buf, len) < 0) {
		/* Because this function most probably got called to log
		 * an error message, any write error is ignored here to
		 * avoid an endless loop. But casting the result of write()
		 * to "void" doesn't satisfy the GNU C code attribute
		 * "warn_unused_result" which is used by some versions of
		 * glibc (e.g. 2.11.1), therefore this silly error
		 * "handling" code here :-( */
		return;
	}
} /* Simple_Error */

/**
 * Get CLIENT structure that belongs to a local connection identified by its
 * index number. Each connection belongs to a client by definition, so it is
 * not required that the caller checks for NULL return values.
 *
 * @param Idx	Connection index number.
 * @returns	Pointer to CLIENT structure.
 */
GLOBAL CLIENT *
Conn_GetClient( CONN_ID Idx )
{
	CONNECTION *c;

	assert(Idx >= 0);
	c = array_get(&My_ConnArray, sizeof (CONNECTION), (size_t)Idx);
	assert(c != NULL);
	return c ? c->client : NULL;
}

/**
 * Get PROC_STAT sub-process structure of a connection.
 *
 * @param Idx	Connection index number.
 * @returns	PROC_STAT structure.
 */
GLOBAL PROC_STAT *
Conn_GetProcStat(CONN_ID Idx)
{
	CONNECTION *c;

	assert(Idx >= 0);
	c = array_get(&My_ConnArray, sizeof (CONNECTION), (size_t)Idx);
	assert(c != NULL);
	return &c->proc_stat;
} /* Conn_GetProcStat */

/**
 * Get CONN_ID from file descriptor associated to a subprocess structure.
 *
 * @param fd	File descriptor.
 * @returns	CONN_ID or NONE (-1).
 */
GLOBAL CONN_ID
Conn_GetFromProc(int fd)
{
	int i;

	assert(fd > 0);
	for (i = 0; i < Pool_Size; i++) {
		if ((My_Connections[i].sock != NONE)
		    && (Proc_GetPipeFd(&My_Connections[i].proc_stat) == fd))
			return i;
	}
	return NONE;
} /* Conn_GetFromProc */

/**
 * Throttle a connection because of excessive usage.
 *
 * @param Reason The reason, see THROTTLE_xxx constants.
 * @param Idx The connection index.
 * @param Client The client of this connection.
 * @param Value The time to delay this connection.
 */
static void
Throttle_Connection(const CONN_ID Idx, CLIENT *Client, const int Reason,
		    unsigned int Value)
{
	assert(Idx > NONE);
	assert(Client != NULL);

	/* Never throttle servers or services, only interrupt processing */
	if (Client_Type(Client) == CLIENT_SERVER
	    || Client_Type(Client) == CLIENT_UNKNOWNSERVER
	    || Client_Type(Client) == CLIENT_SERVICE)
		return;

	/* Don't throttle clients with user mode 'F' set */
	if (Client_HasMode(Client, 'F'))
		return;

	LogDebug("Throttling connection %d: code %d, value %d!", Idx,
		 Reason, Value);
	Conn_SetPenalty(Idx, 1);
}

#ifndef STRICT_RFC

GLOBAL long
Conn_GetAuthPing(CONN_ID Idx)
{
	assert (Idx != NONE);
	return My_Connections[Idx].auth_ping;
} /* Conn_GetAuthPing */

GLOBAL void
Conn_SetAuthPing(CONN_ID Idx, long ID)
{
	assert (Idx != NONE);
	My_Connections[Idx].auth_ping = ID;
} /* Conn_SetAuthPing */

#endif /* STRICT_RFC */

#ifdef SSL_SUPPORT

/**
 * IO callback for new SSL-enabled client and server connections.
 *
 * @param sock	Socket descriptor.
 * @param what	IO specification (IO_WANTREAD/IO_WANTWRITE/...).
 */
static void
cb_clientserver_ssl(int sock, UNUSED short what)
{
	CONN_ID idx = Socket2Index(sock);

	if (idx <= NONE) {
		io_close(sock);
		return;
	}

	switch (ConnSSL_Accept(&My_Connections[idx])) {
		case 1:
			break;	/* OK */
		case 0:
			return;	/* EAGAIN: callback will be invoked again by IO layer */
		default:
			Conn_Close(idx,
				   "SSL accept error, closing socket", "SSL accept error",
				   false);
			return;
	}

	io_event_setcb(sock, cb_clientserver);	/* SSL handshake completed */
}

/**
 * IO callback for listening SSL sockets: handle new connections. This callback
 * gets called when a new SSL-enabled connection should be accepted.
 *
 * @param sock		Socket descriptor.
 * @param irrelevant	(ignored IO specification)
 */
static void
cb_listen_ssl(int sock, short irrelevant)
{
	int fd;

	(void) irrelevant;
	fd = New_Connection(sock, true);
	if (fd < 0)
		return;
	io_event_setcb(My_Connections[fd].sock, cb_clientserver_ssl);
}

/**
 * IO callback for new outgoing SSL-enabled server connections.
 *
 * @param sock		Socket descriptor.
 * @param unused	(ignored IO specification)
 */
static void
cb_connserver_login_ssl(int sock, short unused)
{
	CONN_ID idx = Socket2Index(sock);

	(void) unused;

	if (idx <= NONE) {
		io_close(sock);
		return;
	}

	switch (ConnSSL_Connect( &My_Connections[idx])) {
		case 1: break;
		case 0: LogDebug("ConnSSL_Connect: not ready");
			return;
		case -1:
			Log(LOG_ERR, "SSL connection on socket %d failed!", sock);
			Conn_Close(idx, "Can't connect", NULL, false);
			return;
	}

	Log( LOG_INFO, "SSL connection %d with \"%s:%d\" established.", idx,
	    My_Connections[idx].host, Conf_Server[Conf_GetServer( idx )].port );

	server_login(idx);
}


/**
 * Check if SSL library needs to read SSL-protocol related data.
 *
 * SSL/TLS connections require extra treatment:
 * When either CONN_SSL_WANT_WRITE or CONN_SSL_WANT_READ is set, we
 * need to take care of that first, before checking read/write buffers.
 * For instance, while we might have data in our write buffer, the
 * TLS/SSL protocol might need to read internal data first for TLS/SSL
 * writes to succeed.
 *
 * If this function returns true, such a condition is met and we have
 * to reverse the condition (check for read even if we've data to write,
 * do not check for read but writeability even if write-buffer is empty).
 *
 * @param c	Connection to check.
 * @returns	true if SSL-library has to read protocol data.
 */
static bool
SSL_WantRead(const CONNECTION *c)
{
	if (Conn_OPTION_ISSET(c, CONN_SSL_WANT_READ)) {
		io_event_add(c->sock, IO_WANTREAD);
		return true;
	}
	return false;
}

/**
 * Check if SSL library needs to write SSL-protocol related data.
 *
 * Please see description of SSL_WantRead() for full description!
 *
 * @param c	Connection to check.
 * @returns	true if SSL-library has to write protocol data.
 */
static bool
SSL_WantWrite(const CONNECTION *c)
{
	if (Conn_OPTION_ISSET(c, CONN_SSL_WANT_WRITE)) {
		io_event_add(c->sock, IO_WANTWRITE);
		return true;
	}
	return false;
}

/**
 * Get information about used SSL cipher.
 *
 * @param Idx	Connection index number.
 * @param buf	Buffer for returned information text.
 * @param len	Size of return buffer "buf".
 * @returns	true on success, false otherwise.
 */
GLOBAL bool
Conn_GetCipherInfo(CONN_ID Idx, char *buf, size_t len)
{
	if (Idx < 0)
		return false;
	assert(Idx < (int) array_length(&My_ConnArray, sizeof(CONNECTION)));
	return ConnSSL_GetCipherInfo(&My_Connections[Idx], buf, len);
}

/**
 * Check if a connection is SSL-enabled or not.
 *
 * @param Idx	Connection index number.
 * @return	true if connection is SSL-enabled, false otherwise.
 */
GLOBAL bool
Conn_UsesSSL(CONN_ID Idx)
{
	if (Idx < 0)
		return false;
	assert(Idx < (int) array_length(&My_ConnArray, sizeof(CONNECTION)));
	return Conn_OPTION_ISSET(&My_Connections[Idx], CONN_SSL);
}

GLOBAL char *
Conn_GetCertFp(CONN_ID Idx)
{
	if (Idx < 0)
		return NULL;
	assert(Idx < (int) array_length(&My_ConnArray, sizeof(CONNECTION)));
	return ConnSSL_GetCertFp(&My_Connections[Idx]);
}

GLOBAL bool
Conn_SetCertFp(CONN_ID Idx, const char *fingerprint)
{
	if (Idx < 0)
		return false;
	assert(Idx < (int) array_length(&My_ConnArray, sizeof(CONNECTION)));
	return ConnSSL_SetCertFp(&My_Connections[Idx], fingerprint);
}

#else /* SSL_SUPPORT */

GLOBAL bool
Conn_UsesSSL(UNUSED CONN_ID Idx)
{
	return false;
}

GLOBAL char *
Conn_GetCertFp(UNUSED CONN_ID Idx)
{
	return NULL;
}

GLOBAL bool
Conn_SetCertFp(UNUSED CONN_ID Idx, UNUSED const char *fingerprint)
{
	return true;
}

#endif /* SSL_SUPPORT */

#ifdef DEBUG

/**
 * Dump internal state of the "connection module".
 */
GLOBAL void
Conn_DebugDump(void)
{
	int i;

	Log(LOG_DEBUG, "Connection status:");
	for (i = 0; i < Pool_Size; i++) {
		if (My_Connections[i].sock == NONE)
			continue;
		Log(LOG_DEBUG,
		    " - %d: host=%s, lastdata=%ld, lastping=%ld, delaytime=%ld, flag=%d, options=%d, bps=%d, client=%s",
		    My_Connections[i].sock, My_Connections[i].host,
		    My_Connections[i].lastdata, My_Connections[i].lastping,
		    My_Connections[i].delaytime, My_Connections[i].flag,
		    My_Connections[i].options, My_Connections[i].bps,
		    My_Connections[i].client ? Client_ID(My_Connections[i].client) : "-");
	}
} /* Conn_DumpClients */

#endif /* DEBUG */

/* -eof- */