/*
	File:                  $Source: /usr/drwho/vault/cvs/topsy/MipsSim/ethertap.c,v $
 	Affiliation:           ETH Zuerich, TIK
 	Version:               $Revision: 1.1 $
 	Creation Date:         December 1996
 	Last Date of Change:   $Date: 2000/04/05 14:33:16 $      by: $Author: gfa $
	
	$Log: ethertap.c,v $
	Revision 1.1  2000/04/05 14:33:16  gfa
	*** empty log message ***
	
	
	Usage:
	
	if [[ ! -c /dev/tap0 ]]; then
		mknod /dev/tap0 c 36 16
		chmod go+rw /dev/tap0
	fi
	modprobe ethertap
	ifconfig tap0 192.168.2.1/24 arp
*/

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int setuptap(char *name);
int setupserver(int port);
int setupclient(int sockt);
int setuplog(char *name);
ssize_t sendpacket(int, int, int);
ssize_t recvpacket(int, int, int);

main(int argc, char **argv)
{
	int port, sockt;
	int tapfd, clientfd, maxfd;
	int taplog=0, clientlog=0;
	fd_set fdset;
	struct timeval tv;
	ssize_t len;
	
	if(argc<3) {
		fprintf(stderr,"Syntax: ethertap tapdevice port [tap-log-file] [client-log-file]\n");
		exit(1);
	}
	
	port = atoi(argv[2]);
	
	printf("Starting Ethertap server (v1.1) on port %d.\n", port);

	/* Open tap device */
	tapfd = setuptap(argv[1]);

	/* Open socket */
	sockt = setupserver(port);

	/* Open log files */
	if(argc>3) taplog = setuplog(argv[3]);
	if(argc>4) clientlog = setuplog(argv[4]);
	
	while(1) {
		/* Wait for client */
		clientfd = setupclient(sockt);
	
		if(tapfd>clientfd) maxfd=tapfd+1;
		else               maxfd=clientfd+1;
		
		while(1) {
			FD_ZERO(&fdset);
			FD_SET(tapfd, &fdset);
			FD_SET(clientfd, &fdset);
			tv.tv_sec = 0;
			tv.tv_usec = 1000;
			
			if(select(maxfd, &fdset, NULL, NULL, &tv)) {
				if(FD_ISSET(tapfd, &fdset)) {
					/* fputc('>',stdout); fflush(stdout); */
					len=sendpacket(tapfd,clientfd,taplog);
					if(len<=0) break;
					printf("tap -> client (%d)\n",len);
				}
				if(FD_ISSET(clientfd, &fdset)) {
				        /* fputc('<',stdout); fflush(stdout); */
					len=recvpacket(clientfd,tapfd,clientlog);
					if(len<=0) break;
					printf("tap <- client (%d)\n",len);
				}
			}
		}
		
		close(clientfd);
	}
	
	close(sockt);
	close(tapfd);

	exit(0);
}

int setuptap(char *name)
{
	int fd;
	
	fd = open(name, O_RDWR);
	if(fd < 0) {
		perror(name);
		exit(1);
	}

	return fd;
}

int setuplog(char *name)
{
	int fd;
	
	fd = open(name, O_WRONLY|O_CREAT);
	if(fd < 0) {
		perror(name);
		exit(1);
	}

	return fd;
}


int setupserver(int port)
{
	int s, n=INADDR_ANY;
	int len	= sizeof(struct sockaddr_in);
	struct sockaddr_in name;
	
	/* open socket */
	s = socket(AF_INET, SOCK_STREAM, 0);
	if(s < 0) {
		perror("socket");
		exit(1);
	}

	/* address */
	memset(&name, 0, sizeof(struct sockaddr_in));
	name.sin_family=AF_INET;
	name.sin_port=htons(port);
	memcpy(&name.sin_addr, &n, sizeof(long));

	/* bind */
	if(bind(s,(struct sockaddr *)&name, len)<0) {
		perror("bind");
		exit(1);
	}

	/* listen */
	if(listen(s, 5)<0) {
		perror("listen");
		exit(1);
	}

	return s;
}
	
int setupclient(int s)
{
	int fd;
	int len	= sizeof(struct sockaddr_in);
	struct sockaddr_in name;
	
	puts("Waiting for a client.");
	if((fd = accept(s, (struct sockaddr *) &name, &len)) < 0) {
		perror("accept");
		exit(1);
	}
	puts("Client connected.");

	return fd;
}

ssize_t sendpacket(int from, int to, int log)
{
	char buf[2000];
	ssize_t len;
	int n;

	len=read(from,buf,sizeof(buf));
	if(len > 0) {
		n = write(to,buf+2,len-2); /* What is this 2-bytes-junk at the beginning? */
		if(log) write(log,buf+2,len-2);
		if(n!=len-2) {
			printf("warning: wanted to write: %d, written: %d\n", len-2, n);
		}
	}

	return len-2;
}

ssize_t recvpacket(int from, int to, int log)
{
	char buf[2000];
	ssize_t len;

	len=read(from,buf+2,sizeof(buf));
	buf[0]=0;
	buf[1]=0;
	if(len > 0) {
		len=write(to,buf,len+2);
		if(log) write(log,buf,len);
		if(len>2) len-=2;
	}
	return len;
}