#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>

#define DBG 0

int parseparams(int argc, char *argv[], ulong *adres, uint *rport, uint *lport, uint *service)
{
	char *s;
	uint c, d;
	
	if (argc<1) return 255;
	
	*lport=80;
	*service=113;
	
	switch (argc)
	{
		case 2:
			fprintf(stderr,"Error: missing remote port!\n");
		case 1:
			fprintf(stderr,"Usage: ident <xxx.xxx.xxx.xxx> <remote port> [local port] [ident port]\n");
			return 1;
		default:
		case 5:
			c=0;
			s=argv[4];
			while (*s)
			{
				if (c<65536 && *s>='0' && *s<='9') c=c*10+*s-'0';
				else
				{
					fprintf(stderr,"Error: wrong ident port!\n");
					return 5;
				}
				s++;
			}
			*service=c;
		case 4:
			c=0;
			s=argv[3];
			while (*s)
			{
				if (c<65536 && *s>='0' && *s<='9') c=c*10+*s-'0';
				else
				{
					fprintf(stderr,"Error: wrong local port!\n");
					return 4;
				}
				s++;
			}
			*lport=c;
		case 3:
			*adres=0;
			c=d=0;
			s=argv[1];
			while (*s)
			{	
				if (*s>='0' && *s<='9') 
				{
					c=c*10+*s-'0';
					if (c>255)
					{
						fprintf(stderr,"Error: wrong address!\n");
						return 2;
					}
				}
				else
					if (*s=='.')
					{
						*adres=*adres*256+c;
						c=0;
						if (d++>=3)
						{
							fprintf(stderr,"Error: wrong address!\n");
							return 2;
						}
					}
					else 
					{
						fprintf(stderr,"Error: wrong address!\n"); 
						return 2;
					}
				s++;
			}
			*adres=*adres*256+c;
			
			c=0;
			s=argv[2];
			while (*s)
			{
				if (c<65536 && *s>='0' && *s<='9') c=c*10+*s-'0';
				else
				{
					fprintf(stderr,"Error: wrong remote port!\n");
					return 3;
				}
				s++;
			}
			*rport=c;
	}
	return 0;
}

int main(int argc, char *argv[])
{
	int sock;
	struct sockaddr_in addr;
	char buf[256];
	int count;
	ulong adres;
	uint rport, lport, service;
	int err;
	static const int val_one=1;

	if (parseparams(argc,argv,&adres,&rport,&lport,&service)) return 3;

	if (DBG) fprintf(stderr,"addr: %lX  rport: %u  lport: %u  service: %i\n",adres,rport,lport,service);

	addr.sin_family=AF_INET;
	addr.sin_addr.s_addr=htonl(adres);
	addr.sin_port=htons(service);

	sock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
	setsockopt(sock,SOL_SOCKET,SO_KEEPALIVE,&val_one,sizeof(val_one));

	if (DBG) 
	{
		err=errno;
		fprintf(stderr,"socket: %i, errno: %i\n",sock,err);
	}
	if (sock==-1) 
	{
		fprintf(stderr,"Error: cannot create socket!\n");
		return 4;
	}

	count=connect(sock,(struct sockaddr*)&addr,sizeof(addr));
	if (DBG)
	{
		err=errno;
		fprintf(stderr,"connect: %i, errno: %i\n",count,err);	
	}

	if (count)
	{
		fprintf(stderr,"Error: connection failed!\n");
		return 5;
	}

	count=snprintf(buf,sizeof(buf),"%d , %d\n",rport,lport);
	if (count==-1) return 1;
	if (write(sock,buf,count)!=count) return 2;
	
	for (;;)
	{
		count=read(sock,buf,sizeof(buf)-1);
		if (count<=0) break;
		buf[count]=0;
		printf("%s",buf);
		fflush(stdout);
	}

	if (DBG) fprintf(stderr,"count = %d , errno = %d\n",count,errno);
	close(sock);
	return 0;
}