/*
	by hkpco (ChanAm Park)
	hkpco@korea.com
	http://hkpco.kr/

	irc bot program
*/

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdarg.h>

void pong( int sockfd, char *ping, int sz );
// keep-alive¸¦ À§ÇÑ ÇÔ¼ö

int irc_req( int sockfd, char *req, ... );
// request¸¦ º¸³»±â À§ÇÑ ÇÔ¼ö

int main( int argc , char **argv )
{
	pid_t pid;
	int sockfd, port, status;
	struct sockaddr_in sock;
	struct hostent *host_st;
	char nickname[64] = {0x00,}, channel[64] = {0x00,};
	char rcv_data[4096] = {0x00,}, tmp_buf[64+2] = {0x00,}, *strp;

	if( argc < 5 ) {
		fprintf( stderr, "%s <irc_server> <port> <nickname> <channel>\n", argv[0] );
		return -1;
	}

	/******* µ¥¸ó ÇÁ·Î±×·¥À» À§ÇÑ ¼¼Æà *******/
	pid = fork();
	if( pid < 0 ) {
		perror( "fork()" );
		return -1;
	}
	else if( pid != 0 ) {
		return 0;
	}
	else {
		setsid();
	}
	/******* ¼¼Æà ³¡ *******/

	printf( "\n\n<code by hkpco>\n\n" );

	/******* Á¢¼Ó Á¤º¸ ÀúÀå *******/
	port = atoi(argv[2]);

	strncpy( nickname, argv[3], sizeof(nickname) -1 );

	strncpy( channel, "#", 1 );
	strncat( channel, argv[4], sizeof(channel) -2 );
	/******* Á¢¼Ó Á¤º¸ ÀúÀå ³¡ *******/

	host_st = gethostbyname(argv[1]);
	if( host_st == NULL ) {
		perror( "gethostbyname()" );
		return -1;
	}

	if( argc > 2 )
		port = atoi(argv[2]);

	sockfd = socket( PF_INET, SOCK_STREAM, 0 );
	if( sockfd < 0 ) {
		perror( "socket()" );
		return -1;
	}

	bzero( sock.sin_zero, sizeof(sock.sin_zero) );
	sock.sin_family = AF_INET;
	sock.sin_port = htons(port);
	sock.sin_addr = *((struct in_addr *)host_st->h_addr);

	if( connect( sockfd, (struct sockaddr *)&sock, sizeof(sock) ) < 0 ) {
		perror( "connect()" );
		return -1;
	}

	/******* IRC Ãʱâ Á¢¼Ó *******/
	irc_req( sockfd, "NICK", nickname, NULL );
	read( sockfd, rcv_data,  sizeof(rcv_data) );
	printf( "Response:\n%s\n\n", rcv_data );
	memset( rcv_data, 0x0, sizeof(rcv_data) );

	memset( tmp_buf , 0x0, sizeof(tmp_buf));
	snprintf( tmp_buf, sizeof(tmp_buf) -1, ":%s\n", nickname );

	irc_req( sockfd, "USER", nickname, ". ." , tmp_buf , NULL );
	read( sockfd, rcv_data, sizeof(rcv_data) );
	printf( "Response:\n%s\n\n", rcv_data );

	if( (strp = strstr( rcv_data, "PING" )) == NULL ) {
		memset( rcv_data, 0x0, sizeof(rcv_data) );
		read( sockfd, rcv_data, sizeof(rcv_data) );

		strp = strstr( rcv_data, "PING" );
		pong( sockfd, strp, strlen(strp) );
	}
	else {
		pong( sockfd, strp, strlen(strp) );
	}

	memset( rcv_data, 0x0, sizeof(rcv_data) );
	read( sockfd, rcv_data, sizeof(rcv_data) );
	printf( "Response:\n%s\n\n", rcv_data );

	irc_req( sockfd, "USERHOST", nickname, NULL );
	read( sockfd, rcv_data, sizeof(rcv_data) );
	printf( "Response:\n%s\n\n", rcv_data );
	memset( rcv_data, 0x0, sizeof(rcv_data) );

	irc_req( sockfd, "JOIN", channel, NULL );
	read( sockfd, rcv_data, sizeof(rcv_data) );
	printf( "Response:\n%s\n\n", rcv_data );
	memset( rcv_data, 0x0, sizeof(rcv_data) );

	irc_req( sockfd, "PRIVMSG", channel, ":bot of hkpco.", NULL );
	read( sockfd, rcv_data, sizeof(rcv_data) );
	memset( rcv_data, 0x0, sizeof(rcv_data) );
	/******* IRC Ãʱâ Á¢¼Ó ³¡ *******/

	/******* ¸Þ½ÃÁö ó¸® *******/
	while(1)
	{
		fd_set fds;
		int cmd_pps[2];
		pid_t cmd_prcs;
		char cmd_buf[1024] = {0x00,}, buf_snd[2048] = {0x00,};;
		char buf[1024] = {0x00,}, *p;

		FD_ZERO(&fds);
		FD_SET( sockfd, &fds );

		if( (select( sockfd +1, &fds, (fd_set *)NULL, (fd_set *)NULL, (struct timeval*)NULL )) < 0 ) {
			perror( "select()" );
			return -1;
		}

		if( FD_ISSET( sockfd, &fds ) ) {
			read( sockfd, buf, sizeof(buf) -1 );

			if( (p = strstr( buf, "PING" )) ) {
				pong( sockfd, p, strlen(p) );
			}

			else if( strstr( buf, "whoareyou?" ) ) {
				if( pipe(cmd_pps) < 0 ) {
					perror( "pipe()" );
					continue;
				}
				// ÀÚ½Ä ÇÁ·Î¼¼½º¿ÍÀÇ Åë½ÅÀ» À§ÇÑ pipe »ý¼º

				if( (cmd_prcs = fork()) < 0 ) {
					perror( "fork()" );
					continue;
				}

				if( cmd_prcs == 0 ) {
					dup2( cmd_pps[1], 1 );
					dup2( cmd_pps[1], 2 );
					close(cmd_pps[0]);
					close(cmd_pps[1]);
					execl( "/usr/bin/id", "-a", NULL );
					// id ¸í·ÉÀÇ °á°ú´Â ÆÄÀÌÇÁ¸¦ ÅëÇÏ¿© Àü¼ÛµÊ

					return 0;
				}
				else {
					read( cmd_pps[0], cmd_buf, sizeof(cmd_buf) -1 );
					// ÆÄÀÌÇÁ¸¦ ÅëÇÏ¿© ÀÚ½Ä ÇÁ·Î¼¼½ºÀÇ id ¸í·É °á°ú¸¦ ¼ö½Å

					snprintf( buf_snd, sizeof(buf_snd) -1, "PRIVMSG %s :%s\n", channel, cmd_buf );
					write( sockfd, buf_snd, strlen(buf_snd) );

					close(cmd_pps[0]);
					close(cmd_pps[1]);
				}

				waitpid( cmd_prcs, &status, 0 );
			}

			// irc bot Á¾·á ¸í·É üũ
			else if( strstr( buf, "!go_away" ) ) {
				break;
			}

			memset( buf, 0x0, sizeof(buf) );
			memset( cmd_buf, 0x0, sizeof(cmd_buf) );
			memset( buf_snd, 0x0, sizeof(buf_snd) );
		}
	}
	/******* ¸Þ½ÃÁö ó¸® ³¡ *******/

	printf( "\n[-] EXIT\n" );
	close(sockfd);
	return 0;
}

void pong( int sockfd, char *ping, int sz )
{
	int cnt;
	char buffer[4096] = {0x00,};

	strncpy( buffer, ping, sz );
	memcpy( buffer, "PONG", 4 );

	for( cnt = 1 ; cnt < sz ; cnt++ )
	{
		if( buffer[cnt] == '\n' )
			break;
	}
	
	write( sockfd, buffer, cnt );
	printf( "Request:\n" );
	write( 1, buffer, cnt );
	printf( "\n\n" );

}

int irc_req( int sockfd, char *req, ... )
{
	va_list v_arg;
	char buffer[4096] = {0x00,};
	char *ptr;

	strncpy( buffer, req, sizeof(buffer) -1 );

	va_start( v_arg, req );
	while( (ptr = va_arg( v_arg, char* )) != NULL )
	{
		strncat( buffer, " ", sizeof(buffer) -1 );
		strncat( buffer, ptr, sizeof(buffer) -1 );
	}

	strncat( buffer, "\n", sizeof(buffer) -1 );
	write( sockfd, buffer, strlen(buffer) );
	printf( "Request:\n%s\n\n", buffer );

	return 0;
}