path: root/src/logger/win32/syslog_win32.c

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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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/*
 * syslog-client.c - syslog client implementation for windows
 *
 * Created by Alexander Yaworsky
 *
 * THIS SOFTWARE IS NOT COPYRIGHTED
 *
 * This source code is offered for use in the public domain. You may
 * use, modify or distribute it freely.
 *
 * This code is distributed in the hope that it will be useful but
 * WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
 * DISCLAIMED. This includes but is not limited to warranties of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

/**
 * \file syslog_win32.c
 * \brief implementation of a syslog client on Windows
 *
 * It is roughly based on the one of http://syslog-win32.sourceforge.net,
 * changed in the way it's configured (we can't have a /etc/syslog.conf
 * on Windows, host and port must be injectable through a function from
 * the Wolframe configuration), in the way the messages are composed using
 * newer string functions, using WSock2 funtions like getaddrinfo and
 * some small other things like added documentation.
*/

/* TODOS:
 * - reset logmask in openlog?
 * - handle more options
 */

#include "syslog_win32.h"

#include <Winsock2.h>
#include <ws2tcpip.h>
#include <string.h>
#include <stdio.h>

static BOOL initialized = FALSE;
static BOOL wsa_initialized = FALSE;

static int log_mask = 0xFF;
static const char *syslog_ident = NULL;
static int syslog_facility = 0;
static char str_pid[40];
static char local_hostname[MAX_COMPUTERNAME_LENGTH+4];

static char syslog_hostname[256] = "localhost";
static char syslog_service[256] = "514";

/* UDP socket and data to use for sending messages */
static SOCKADDR_STORAGE sa_logger;
static SOCKET sock = INVALID_SOCKET;
#define SYSLOG_DGRAM_SIZE 1024
static char datagram[SYSLOG_DGRAM_SIZE];
static int datagram_size = SYSLOG_DGRAM_SIZE;

void openlog( const char* ident, int option, int facility )
{
	BOOL failed = TRUE;
	WSADATA wsd;
	struct addrinfo hints;
	struct addrinfo *result = NULL;
	SOCKADDR_IN sa_local;
	int size;
	DWORD n;
	
	/* allow idempotent calls, first options are taken, use closelog
	 * before openlog if you want to reconfigure the syslog interface
	 */
	if( initialized ) return;

	/* Initialize Windows Socket DLL */
	if( WSAStartup( MAKEWORD( 2, 2 ), &wsd ) != 0 ) goto DONE;
	wsa_initialized = TRUE;

	/* tell getaddrinfo what we want */
	memset( &hints, 0, sizeof( struct addrinfo ) );
	hints.ai_flags = 0;
	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_DGRAM;
	hints.ai_protocol = IPPROTO_UDP;
 
	/* resolve the domain name into a list of addresses */
	if( getaddrinfo( syslog_hostname, syslog_service, &hints, &result ) != 0 ) goto DONE;

	/* Compose the socket address and port of the logging destination */
	memset( &sa_logger, 0, sizeof( SOCKADDR_IN ) );
	memcpy( &sa_logger, result->ai_addr, result->ai_addrlen );

	/* Create a UDP socket */
	sock = socket( result->ai_family, result->ai_socktype, result->ai_protocol );
	if( sock == INVALID_SOCKET ) goto DONE;
	
	/* from RFC 3164: The client should connect from a constant port, if possible
	 * also port 514.
	 *
	 * But if we are on the same machine with loopback the port is taken?
	 * Should we try 514 and if it is taken take a fixed different one?
	 */
	
	/* bind to the socket */
	memset( &sa_local, 0, sizeof( SOCKADDR_IN ) );
	sa_local.sin_family = AF_INET;
	if( bind( sock, (SOCKADDR *)&sa_local, sizeof( SOCKADDR_IN ) ) != 0 ) goto DONE;

	/* determine the maximal size of a datagram packet we can send */
	size = sizeof( datagram_size );
	if( getsockopt( sock, SOL_SOCKET, SO_MAX_MSG_SIZE, (char *)&datagram_size, &size ) != 0 ) goto DONE;
	if( datagram_size > sizeof( datagram ) ) datagram_size = sizeof( datagram );
	
	/* set global facility and ident */
	syslog_facility = facility ? facility : LOG_USER;
	syslog_ident = ident;

	/* by RFC 3164 we should put here the name of the local machine */
	n = sizeof( local_hostname );
	if( !GetComputerName( local_hostname, &n ) ) goto DONE;
	
	/* interpret options, currently we use only LOG_PID */
	if( option & LOG_PID )
		_snprintf_s( str_pid, sizeof( str_pid ), _TRUNCATE, "[%lu]", GetCurrentProcessId( ) );
	else
		str_pid[0] = '\0';
	
	/* install C cleanup function */
	if( atexit( closelog ) ) goto DONE;
	
	/* if we get here, everything's peachy */
	failed = FALSE;
	
DONE:
	if( failed ) {
		if( sock != INVALID_SOCKET ) {
			closesocket( sock );
			sock = INVALID_SOCKET;
		}
		if( wsa_initialized ) {
			wsa_initialized = FALSE;
			WSACleanup( );
		}
	}
	
	initialized = !failed;
}

extern int setlogmask( int mask )
{
	/* set log mask, return old one */
	int old_mask = log_mask;
	
	if( mask ) log_mask = mask;	
	
	return old_mask;
}

void syslog( int pri, char* fmt, ... )
{
	va_list ap;
	va_start( ap, fmt );
	vsyslog( pri, fmt, ap );
	va_end( ap );
}
	
void vsyslog( int pri, char* fmt, va_list ap )
{
	/* from RFC 3164: Mmm is the English language abbreviation for the month of the
	 * year with the first character in uppercase and the other two
	 * characters in lowercase.  The following are the only acceptable
	 * values:
	 *
	 * Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
	 */
	static char *month[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	                        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };

	int len;
	SYSTEMTIME t;

	/* do not log if we are not inside the logging mask */
	if( !( LOG_MASK( LOG_PRI( pri ) ) & log_mask ) ) return;

	/* open default logger, will return immediatelly if already
	 * registered before */
	openlog( NULL, 0, pri & LOG_FACMASK );

	/* do not log if not initialized after opening a default log */
	if( !initialized ) return;

	if( !( pri & LOG_FACMASK ) ) pri |= syslog_facility;

	/* from RFC 3164: .. hh:mm:ss is the local time. .. */
	GetLocalTime( &t );
	
	/* the PRI and the HEADER with TIMESTAMP and HOSTNAME as
	 * well as the TAG field of the MSG part
	 */
	len = _snprintf_s( datagram, datagram_size, _TRUNCATE, "<%d>%s %2d %02d:%02d:%02d %s %s%s: ",
		pri, month[t.wMonth-1], t.wDay, t.wHour, t.wMinute, t.wSecond,
		local_hostname, syslog_ident ? syslog_ident : "", str_pid );

	/* append now the formatted user message */
	(void)_vsnprintf_s( datagram + len, datagram_size - len, _TRUNCATE, fmt, ap );

	/* send as datagram, we are not really interested in errors here */
	(void)sendto( sock, datagram, strlen( datagram ), 0, (SOCKADDR *)&sa_logger, sizeof( SOCKADDR_IN ) );
}

void closelog( )
{
	if( !initialized ) return;
	
	if( sock != INVALID_SOCKET ) (void)closesocket( sock );
	if( wsa_initialized ) WSACleanup( );

	sock = INVALID_SOCKET;
	wsa_initialized	= FALSE;
	initialized = FALSE;	
}

void set_syslogd_destination( const char *hostname, const char *service )
{
	strncpy_s( syslog_hostname, 255, hostname, _TRUNCATE );
	strncpy_s( syslog_service, 255, service, _TRUNCATE );
}