l4check/l4check.c - net/ipfilter - Rivoreo Source Code Repositories

 /*
  * (C)Copyright (C) 2012 by Darren Reed.
  */
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/ioctl.h>

 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>

 #include <net/if.h>

 #include <stdio.h>
 #include <netdb.h>
 #include <string.h>
 #include <ctype.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <stdlib.h>

 #include "ip_compat.h"
 #include "ip_fil.h"
 #include "ip_nat.h"

 #include "ipf.h"

 extern	char	*optarg;


 typedef	struct	l4cfg	{
 	struct	l4cfg		*l4_next;
 	struct	ipnat		l4_nat;		/* NAT rule */
 	struct	sockaddr_in	l4_sin;		/* remote socket to connect */
 	time_t			l4_last;	/* when we last connected */
 	int			l4_alive;	/* 1 = remote alive */
 	int			l4_fd;
 	int			l4_rw;		/* 0 = reading, 1 = writing */
 	char			*l4_rbuf;	/* read buffer */
 	int			l4_rsize;	/* size of buffer */
 	int			l4_rlen;	/* how much used */
 	char			*l4_wptr;	/* next byte to write */
 	int			l4_wlen;	/* length yet to be written */
 } l4cfg_t;


 l4cfg_t *l4list = NULL;
 char *response = NULL;
 char *probe = NULL;
 l4cfg_t template;
 int frequency = 20;
 int ctimeout = 1;
 int rtimeout = 1;
 size_t plen = 0;
 size_t rlen = 0;
 int natfd = -1;
 int opts = 0;

 #if defined(sun) && !defined(__svr4__) && !defined(__SVR4)
 # define	strerror(x)	sys_errlist[x]
 #endif


 char *copystr(dst, src)
 	char *dst, *src;
 {
 	register char *s, *t, c;
 	register int esc = 0;

 	for (s = src, t = dst; s && t && (c = *s++); )
 		if (esc) {
 			esc = 0;
 			switch (c)
 			{
 			case 'n' :
 				*t++ = '\n';
 				break;
 			case 'r' :
 				*t++ = '\r';
 				break;
 			case 't' :
 				*t++ = '\t';
 				break;
 			}
 		} else if (c != '\\')
 			*t++ = c;
 		else
 			esc = 1;
 	*t = '\0';
 	return dst;
 }

 void addnat(l4)
 	l4cfg_t *l4;
 {
 	ipnat_t *ipn = &l4->l4_nat;

 	printf("Add NAT rule for %s/%#x,%u -> ", inet_ntoa(ipn->in_out[0]),
 		ipn->in_outmsk, ntohs(ipn->in_pmin));
 	printf("%s,%u\n", inet_ntoa(ipn->in_in[0]), ntohs(ipn->in_pnext));
 	if (!(opts & OPT_DONOTHING)) {
 		if (ioctl(natfd, SIOCADNAT, &ipn) == -1)
 			perror("ioctl(SIOCADNAT)");
 	}
 }


 void delnat(l4)
 	l4cfg_t *l4;
 {
 	ipnat_t *ipn = &l4->l4_nat;

 	printf("Remove NAT rule for %s/%#x,%u -> ",
 		inet_ntoa(ipn->in_out[0]), ipn->in_outmsk, ipn->in_pmin);
 	printf("%s,%u\n", inet_ntoa(ipn->in_in[0]), ipn->in_pnext);
 	if (!(opts & OPT_DONOTHING)) {
 		if (ioctl(natfd, SIOCRMNAT, &ipn) == -1)
 			perror("ioctl(SIOCRMNAT)");
 	}
 }


 void connectl4(l4)
 	l4cfg_t *l4;
 {
 	l4->l4_rw = 1;
 	l4->l4_rlen = 0;
 	l4->l4_wlen = plen;
 	if (!l4->l4_wlen) {
 		l4->l4_alive = 1;
 		addnat(l4);
 	} else
 		l4->l4_wptr = probe;
 }


 void closel4(l4, dead)
 	l4cfg_t *l4;
 	int dead;
 {
 	close(l4->l4_fd);
 	l4->l4_fd = -1;
 	l4->l4_rw = -1;
 	if (dead && l4->l4_alive) {
 		l4->l4_alive = 0;
 		delnat(l4);
 	}
 }


 void connectfd(l4)
 	l4cfg_t *l4;
 {
 	if (connect(l4->l4_fd, (struct sockaddr *)&l4->l4_sin,
 		    sizeof(l4->l4_sin)) == -1) {
 		if (errno == EISCONN) {
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr, "Connected fd %d\n",
 					l4->l4_fd);
 			connectl4(l4);
 			return;
 		}
 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "Connect failed fd %d: %s\n",
 				l4->l4_fd, strerror(errno));
 		closel4(l4, 1);
 		return;
 	}
 	l4->l4_rw = 1;
 }


 void writefd(l4)
 	l4cfg_t *l4;
 {
 	char buf[80], *ptr;
 	int n, i, fd;

 	fd = l4->l4_fd;

 	if (l4->l4_rw == -2) {
 		connectfd(l4);
 		return;
 	}

 	n = l4->l4_wlen;

 	i = send(fd, l4->l4_wptr, n, 0);
 	if (i == 0 || i == -1) {
 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "Send on fd %d failed: %s\n",
 				fd, strerror(errno));
 		closel4(l4, 1);
 	} else {
 		l4->l4_wptr += i;
 		l4->l4_wlen -= i;
 		if (l4->l4_wlen == 0)
 			l4->l4_rw = 0;
 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "Sent %d bytes to fd %d\n", i, fd);
 	}
 }


 void readfd(l4)
 	l4cfg_t *l4;
 {
 	char buf[80], *ptr;
 	int n, i, fd;

 	fd = l4->l4_fd;

 	if (l4->l4_rw == -2) {
 		connectfd(l4);
 		return;
 	}

 	if (l4->l4_rsize) {
 		n = l4->l4_rsize - l4->l4_rlen;
 		ptr = l4->l4_rbuf + l4->l4_rlen;
 	} else {
 		n = sizeof(buf) - 1;
 		ptr = buf;
 	}

 	if (opts & OPT_VERBOSE)
 		fprintf(stderr, "Read %d bytes on fd %d to %p\n",
 			n, fd, ptr);
 	i = recv(fd, ptr, n, 0);
 	if (i == 0 || i == -1) {
 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "Read error on fd %d: %s\n",
 				fd, (i == 0) ? "EOF" : strerror(errno));
 		closel4(l4, 1);
 	} else {
 		if (ptr == buf)
 			ptr[i] = '\0';
 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "%d: Read %d bytes [%*.*s]\n",
 				fd, i, i, i, ptr);
 		if (ptr != buf) {
 			l4->l4_rlen += i;
 			if (l4->l4_rlen >= l4->l4_rsize) {
 				if (!strncmp(response, l4->l4_rbuf,
 					     l4->l4_rsize)) {
 					printf("%d: Good response\n",
 						fd);
 					if (!l4->l4_alive) {
 						l4->l4_alive = 1;
 						addnat(l4);
 					}
 					closel4(l4, 0);
 				} else {
 					if (opts & OPT_VERBOSE)
 						printf("%d: Bad response\n",
 							fd);
 					closel4(l4, 1);
 				}
 			}
 		} else if (!l4->l4_alive) {
 			l4->l4_alive = 1;
 			addnat(l4);
 			closel4(l4, 0);
 		}
 	}
 }


 int runconfig()
 {
 	int fd, opt, res, mfd, i;
 	struct timeval tv;
 	time_t now, now1;
 	fd_set rfd, wfd;
 	l4cfg_t *l4;

 	mfd = 0;
 	opt = 1;
 	now = time(NULL);

 	/*
 	 * First, initiate connections that are closed, as required.
 	 */
 	for (l4 = l4list; l4; l4 = l4->l4_next) {
 		if ((l4->l4_last + frequency < now) && (l4->l4_fd == -1)) {
 			l4->l4_last = now;
 			fd = socket(AF_INET, SOCK_STREAM, 0);
 			if (fd == -1)
 				continue;
 			setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt,
 				   sizeof(opt));
 #ifdef	O_NONBLOCK
 			if ((res = fcntl(fd, F_GETFL, 0)) != -1)
 				fcntl(fd, F_SETFL, res | O_NONBLOCK);
 #endif
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr,
 					"Connecting to %s,%d (fd %d)...",
 					inet_ntoa(l4->l4_sin.sin_addr),
 					ntohs(l4->l4_sin.sin_port), fd);
 			if (connect(fd, (struct sockaddr *)&l4->l4_sin,
 				    sizeof(l4->l4_sin)) == -1) {
 				if (errno != EINPROGRESS) {
 					if (opts & OPT_VERBOSE)
 						fprintf(stderr, "failed\n");
 					perror("connect");
 					close(fd);
 					fd = -1;
 				} else {
 					if (opts & OPT_VERBOSE)
 						fprintf(stderr, "waiting\n");
 					l4->l4_rw = -2;
 				}
 			} else {
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr, "connected\n");
 				connectl4(l4);
 			}
 			l4->l4_fd = fd;
 		}
 	}

 	/*
 	 * Now look for fd's which we're expecting to read/write from.
 	 */
 	FD_ZERO(&rfd);
 	FD_ZERO(&wfd);
 	tv.tv_sec = MIN(rtimeout, ctimeout);
 	tv.tv_usec = 0;

 	for (l4 = l4list; l4; l4 = l4->l4_next)
 		if (l4->l4_rw == 0) {
 			if (now - l4->l4_last > rtimeout) {
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr, "%d: Read timeout\n",
 						l4->l4_fd);
 				closel4(l4, 1);
 				continue;
 			}
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr, "Wait for read on fd %d\n",
 					l4->l4_fd);
 			FD_SET(l4->l4_fd, &rfd);
 			if (l4->l4_fd > mfd)
 				mfd = l4->l4_fd;
 		} else if ((l4->l4_rw == 1 && l4->l4_wlen) ||
 			   l4->l4_rw == -2) {
 			if ((l4->l4_rw == -2) &&
 			    (now - l4->l4_last > ctimeout)) {
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"%d: connect timeout\n",
 						l4->l4_fd);
 				closel4(l4);
 				continue;
 			}
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr, "Wait for write on fd %d\n",
 					l4->l4_fd);
 			FD_SET(l4->l4_fd, &wfd);
 			if (l4->l4_fd > mfd)
 				mfd = l4->l4_fd;
 		}

 	if (opts & OPT_VERBOSE)
 		fprintf(stderr, "Select: max fd %d wait %d\n", mfd + 1,
 			tv.tv_sec);
 	i = select(mfd + 1, &rfd, &wfd, NULL, &tv);
 	if (i == -1) {
 		perror("select");
 		return -1;
 	}

 	now1 = time(NULL);

 	for (l4 = l4list; (i > 0) && l4; l4 = l4->l4_next) {
 		if (l4->l4_fd < 0)
 			continue;
 		if (FD_ISSET(l4->l4_fd, &rfd)) {
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr, "Ready to read on fd %d\n",
 					l4->l4_fd);
 			readfd(l4);
 			i--;
 		}

 		if ((l4->l4_fd >= 0) && FD_ISSET(l4->l4_fd, &wfd)) {
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr, "Ready to write on fd %d\n",
 					l4->l4_fd);
 			writefd(l4);
 			i--;
 		}
 	}
 	return 0;
 }


 int gethostport(str, lnum, ipp, portp)
 	char *str;
 	int lnum;
 	u_32_t *ipp;
 	u_short *portp;
 {
 	struct servent *sp;
 	struct hostent *hp;
 	char *host, *port;
 	struct in_addr ip;

 	host = str;
 	port = strchr(host, ',');
 	if (port)
 		*port++ = '\0';

 #ifdef	HAVE_INET_ATON
 	if (ISDIGIT(*host) && inet_aton(host, &ip))
 		*ipp = ip.s_addr;
 #else
 	if (ISDIGIT(*host))
 		*ipp = inet_addr(host);
 #endif
 	else {
 		if (!(hp = gethostbyname(host))) {
 			fprintf(stderr, "%d: can't resolve hostname: %s\n",
 				lnum, host);
 			return 0;
 		}
 		*ipp = *(u_32_t *)hp->h_addr;
 	}

 	if (port) {
 		if (ISDIGIT(*port))
 			*portp = htons(atoi(port));
 		else {
 			sp = getservbyname(port, "tcp");
 			if (sp)
 				*portp = sp->s_port;
 			else {
 				fprintf(stderr, "%d: unknown service %s\n",
 					lnum, port);
 				return 0;
 			}
 		}
 	} else
 		*portp = 0;
 	return 1;
 }


 char *mapfile(file, sizep)
 	char *file;
 	size_t *sizep;
 {
 	struct stat sb;
 	caddr_t addr;
 	int fd;

 	fd = open(file, O_RDONLY);
 	if (fd == -1) {
 		perror("open(mapfile)");
 		return NULL;
 	}

 	if (fstat(fd, &sb) == -1) {
 		perror("fstat(mapfile)");
 		close(fd);
 		return NULL;
 	}

 	addr = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
 	if (addr == (caddr_t)-1) {
 		perror("mmap(mapfile)");
 		close(fd);
 		return NULL;
 	}
 	close(fd);
 	*sizep = sb.st_size;
 	return (char *)addr;
 }


 int readconfig(filename)
 	char *filename;
 {
 	char c, buf[512], *s, *t, *errtxt = NULL, *line;
 	int num, err = 0;
 	ipnat_t *ipn;
 	l4cfg_t *l4;
 	FILE *fp;

 	fp = fopen(filename, "r");
 	if (!fp) {
 		perror("open(configfile)");
 		return -1;
 	}

 	bzero((char *)&template, sizeof(template));
 	template.l4_fd = -1;
 	template.l4_rw = -1;
 	template.l4_sin.sin_family = AF_INET;
 	ipn = &template.l4_nat;
 	ipn->in_flags = IPN_TCP|IPN_ROUNDR;
 	ipn->in_redir = NAT_REDIRECT;

 	for (num = 1; fgets(buf, sizeof(buf), fp); num++) {
 		s = strchr(buf, '\n');
 		if  (!s) {
 			fprintf(stderr, "%d: line too long\n", num);
 			fclose(fp);
 			return -1;
 		}

 		*s = '\0';

 		/*
 		 * lines which are comments
 		 */
 		s = strchr(buf, '#');
 		if (s)
 			*s = '\0';

 		/*
 		 * Skip leading whitespace
 		 */
 		for (line = buf; (c = *line) && ISSPACE(c); line++)
 			;
 		if (!*line)
 			continue;

 		if (opts & OPT_VERBOSE)
 			fprintf(stderr, "Parsing: [%s]\n", line);
 		t = strtok(line, " \t");
 		if (!t)
 			continue;
 		if (!strcasecmp(t, "interface")) {
 			s = strtok(NULL, " \t");
 			if (s)
 				t = strtok(NULL, "\t");
 			if (!s || !t) {
 				errtxt = line;
 				err = -1;
 				break;
 			}

 			if (!strchr(t, ',')) {
 				fprintf(stderr,
 					"%d: local address,port missing\n",
 					num);
 				err = -1;
 				break;
 			}

 			strncpy(ipn->in_ifname, s, sizeof(ipn->in_ifname));
 			if (!gethostport(t, num, &ipn->in_outip,
 					 &ipn->in_pmin)) {
 				errtxt = line;
 				err = -1;
 				break;
 			}
 			ipn->in_outmsk = 0xffffffff;
 			ipn->in_pmax = ipn->in_pmin;
 			if (opts & OPT_VERBOSE)
 				fprintf(stderr,
 					"Interface %s %s/%#x port %u\n",
 					ipn->in_ifname,
 					inet_ntoa(ipn->in_out[0]),
 					ipn->in_outmsk, ipn->in_pmin);
 		} else if (!strcasecmp(t, "remote")) {
 			if (!*ipn->in_ifname) {
 				fprintf(stderr,
 					"%d: ifname not set prior to remote\n",
 					num);
 				err = -1;
 				break;
 			}
 			s = strtok(NULL, " \t");
 			if (s)
 				t = strtok(NULL, "");
 			if (!s || !t || strcasecmp(s, "server")) {
 				errtxt = line;
 				err = -1;
 				break;
 			}

 			ipn->in_pnext = 0;
 			if (!gethostport(t, num, &ipn->in_inip,
 					 &ipn->in_pnext)) {
 				errtxt = line;
 				err = -1;
 				break;
 			}
 			ipn->in_inmsk = 0xffffffff;
 			if (ipn->in_pnext == 0)
 				ipn->in_pnext = ipn->in_pmin;

 			l4 = (l4cfg_t *)malloc(sizeof(*l4));
 			if (!l4) {
 				fprintf(stderr, "%d: out of memory (%d)\n",
 					num, sizeof(*l4));
 				err = -1;
 				break;
 			}
 			bcopy((char *)&template, (char *)l4, sizeof(*l4));
 			l4->l4_sin.sin_addr = ipn->in_in[0];
 			l4->l4_sin.sin_port = ipn->in_pnext;
 			l4->l4_next = l4list;
 			l4list = l4;
 		} else if (!strcasecmp(t, "connect")) {
 			s = strtok(NULL, " \t");
 			if (s)
 				t = strtok(NULL, "\t");
 			if (!s || !t) {
 				errtxt = line;
 				err = -1;
 				break;
 			} else if (!strcasecmp(s, "timeout")) {
 				ctimeout = atoi(t);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr, "connect timeout %d\n",
 						ctimeout);
 			} else if (!strcasecmp(s, "frequency")) {
 				frequency = atoi(t);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"connect frequency %d\n",
 						frequency);
 			} else {
 				errtxt = line;
 				err = -1;
 				break;
 			}
 		} else if (!strcasecmp(t, "probe")) {
 			s = strtok(NULL, " \t");
 			if (!s) {
 				errtxt = line;
 				err = -1;
 				break;
 			} else if (!strcasecmp(s, "string")) {
 				if (probe) {
 					fprintf(stderr,
 						"%d: probe already set\n",
 						num);
 					err = -1;
 					break;
 				}
 				t = strtok(NULL, "");
 				if (!t) {
 					fprintf(stderr,
 						"%d: No probe string\n", num);
 					err = -1;
 					break;
 				}

 				probe = malloc(strlen(t));
 				copystr(probe, t);
 				plen = strlen(probe);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr, "Probe string [%s]\n",
 						probe);
 			} else if (!strcasecmp(s, "file")) {
 				t = strtok(NULL, " \t");
 				if (!t) {
 					errtxt = line;
 					err = -1;
 					break;
 				}
 				if (probe) {
 					fprintf(stderr,
 						"%d: probe already set\n",
 						num);
 					err = -1;
 					break;
 				}
 				probe = mapfile(t, &plen);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"Probe file %s len %u@%p\n",
 						t, plen, probe);
 			}
 		} else if (!strcasecmp(t, "response")) {
 			s = strtok(NULL, " \t");
 			if (!s) {
 				errtxt = line;
 				err = -1;
 				break;
 			} else if (!strcasecmp(s, "timeout")) {
 				t = strtok(NULL, " \t");
 				if (!t) {
 					errtxt = line;
 					err = -1;
 					break;
 				}
 				rtimeout = atoi(t);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"response timeout %d\n",
 						rtimeout);
 			} else if (!strcasecmp(s, "string")) {
 				if (response) {
 					fprintf(stderr,
 						"%d: response already set\n",
 						num);
 					err = -1;
 					break;
 				}
 				response = strdup(strtok(NULL, ""));
 				rlen = strlen(response);
 				template.l4_rsize = rlen;
 				template.l4_rbuf = malloc(rlen);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"Response string [%s]\n",
 						response);
 			} else if (!strcasecmp(s, "file")) {
 				t = strtok(NULL, " \t");
 				if (!t) {
 					errtxt = line;
 					err = -1;
 					break;
 				}
 				if (response) {
 					fprintf(stderr,
 						"%d: response already set\n",
 						num);
 					err = -1;
 					break;
 				}
 				response = mapfile(t, &rlen);
 				template.l4_rsize = rlen;
 				template.l4_rbuf = malloc(rlen);
 				if (opts & OPT_VERBOSE)
 					fprintf(stderr,
 						"Response file %s len %u@%p\n",
 						t, rlen, response);
 			}
 		} else {
 			errtxt = line;
 			err = -1;
 			break;
 		}
 	}

 	if (errtxt)
 		fprintf(stderr, "%d: syntax error at \"%s\"\n", num, errtxt);
 	fclose(fp);
 	return err;
 }


 void usage(prog)
 	char *prog;
 {
 	fprintf(stderr, "Usage: %s -f <configfile>\n", prog);
 	exit(1);
 }


 int main(argc, argv)
 	int argc;
 	char *argv[];
 {
 	char *config = NULL;
 	int c;

 	while ((c = getopt(argc, argv, "f:nv")) != -1)
 		switch (c)
 		{
 		case 'f' :
 			config = optarg;
 			break;
 		case 'n' :
 			opts |= OPT_DONOTHING;
 			break;
 		case 'v' :
 			opts |= OPT_VERBOSE;
 			break;
 		}

 	if (config == NULL)
 		usage(argv[0]);

 	if (readconfig(config))
 		exit(1);

 	if (!l4list) {
 		fprintf(stderr, "No remote servers, exiting.");
 		exit(1);
 	}

 	if (!(opts & OPT_DONOTHING)) {
 		natfd = open(IPL_NAT, O_RDWR);
 		if (natfd == -1) {
 			perror("open(IPL_NAT)");
 			exit(1);
 		}
 	}

 	if (opts & OPT_VERBOSE)
 		fprintf(stderr, "Starting...\n");
 	while (runconfig() == 0)
 		;
 }
	/*
	* (C)Copyright (C) 2012 by Darren Reed.
	*/
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/mman.h>
	#include <sys/socket.h>
	#include <sys/time.h>
	#include <sys/ioctl.h>

	#include <netinet/in.h>
	#include <netinet/in_systm.h>
	#include <netinet/ip.h>

	#include <net/if.h>

	#include <stdio.h>
	#include <netdb.h>
	#include <string.h>
	#include <ctype.h>
	#include <fcntl.h>
	#include <errno.h>
	#include <stdlib.h>

	#include "ip_compat.h"
	#include "ip_fil.h"
	#include "ip_nat.h"

	#include "ipf.h"

	extern char *optarg;


	typedef struct l4cfg {
	struct l4cfg *l4_next;
	struct ipnat l4_nat; /* NAT rule */
	struct sockaddr_in l4_sin; /* remote socket to connect */
	time_t l4_last; /* when we last connected */
	int l4_alive; /* 1 = remote alive */
	int l4_fd;
	int l4_rw; /* 0 = reading, 1 = writing */
	char l4_rbuf; / read buffer */
	int l4_rsize; /* size of buffer */
	int l4_rlen; /* how much used */
	char l4_wptr; / next byte to write */
	int l4_wlen; /* length yet to be written */
	} l4cfg_t;


	l4cfg_t *l4list = NULL;
	char *response = NULL;
	char *probe = NULL;
	l4cfg_t template;
	int frequency = 20;
	int ctimeout = 1;
	int rtimeout = 1;
	size_t plen = 0;
	size_t rlen = 0;
	int natfd = -1;
	int opts = 0;

	#if defined(sun) && !defined(__svr4__) && !defined(__SVR4)
	# define strerror(x) sys_errlist[x]
	#endif


	char *copystr(dst, src)
	char dst, src;
	{
	register char s, t, c;
	register int esc = 0;

	for (s = src, t = dst; s && t && (c = *s++); )
	if (esc) {
	esc = 0;
	switch (c)
	{
	case 'n' :
	*t++ = '\n';
	break;
	case 'r' :
	*t++ = '\r';
	break;
	case 't' :
	*t++ = '\t';
	break;
	}
	} else if (c != '\\')
	*t++ = c;
	else
	esc = 1;
	*t = '\0';
	return dst;
	}

	void addnat(l4)
	l4cfg_t *l4;
	{
	ipnat_t *ipn = &l4->l4_nat;

	printf("Add NAT rule for %s/%#x,%u -> ", inet_ntoa(ipn->in_out[0]),
	ipn->in_outmsk, ntohs(ipn->in_pmin));
	printf("%s,%u\n", inet_ntoa(ipn->in_in[0]), ntohs(ipn->in_pnext));
	if (!(opts & OPT_DONOTHING)) {
	if (ioctl(natfd, SIOCADNAT, &ipn) == -1)
	perror("ioctl(SIOCADNAT)");
	}
	}


	void delnat(l4)
	l4cfg_t *l4;
	{
	ipnat_t *ipn = &l4->l4_nat;

	printf("Remove NAT rule for %s/%#x,%u -> ",
	inet_ntoa(ipn->in_out[0]), ipn->in_outmsk, ipn->in_pmin);
	printf("%s,%u\n", inet_ntoa(ipn->in_in[0]), ipn->in_pnext);
	if (!(opts & OPT_DONOTHING)) {
	if (ioctl(natfd, SIOCRMNAT, &ipn) == -1)
	perror("ioctl(SIOCRMNAT)");
	}
	}


	void connectl4(l4)
	l4cfg_t *l4;
	{
	l4->l4_rw = 1;
	l4->l4_rlen = 0;
	l4->l4_wlen = plen;
	if (!l4->l4_wlen) {
	l4->l4_alive = 1;
	addnat(l4);
	} else
	l4->l4_wptr = probe;
	}


	void closel4(l4, dead)
	l4cfg_t *l4;
	int dead;
	{
	close(l4->l4_fd);
	l4->l4_fd = -1;
	l4->l4_rw = -1;
	if (dead && l4->l4_alive) {
	l4->l4_alive = 0;
	delnat(l4);
	}
	}


	void connectfd(l4)
	l4cfg_t *l4;
	{
	if (connect(l4->l4_fd, (struct sockaddr *)&l4->l4_sin,
	sizeof(l4->l4_sin)) == -1) {
	if (errno == EISCONN) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Connected fd %d\n",
	l4->l4_fd);
	connectl4(l4);
	return;
	}
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Connect failed fd %d: %s\n",
	l4->l4_fd, strerror(errno));
	closel4(l4, 1);
	return;
	}
	l4->l4_rw = 1;
	}


	void writefd(l4)
	l4cfg_t *l4;
	{
	char buf[80], *ptr;
	int n, i, fd;

	fd = l4->l4_fd;

	if (l4->l4_rw == -2) {
	connectfd(l4);
	return;
	}

	n = l4->l4_wlen;

	i = send(fd, l4->l4_wptr, n, 0);
	if (i == 0 \|\| i == -1) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Send on fd %d failed: %s\n",
	fd, strerror(errno));
	closel4(l4, 1);
	} else {
	l4->l4_wptr += i;
	l4->l4_wlen -= i;
	if (l4->l4_wlen == 0)
	l4->l4_rw = 0;
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Sent %d bytes to fd %d\n", i, fd);
	}
	}


	void readfd(l4)
	l4cfg_t *l4;
	{
	char buf[80], *ptr;
	int n, i, fd;

	fd = l4->l4_fd;

	if (l4->l4_rw == -2) {
	connectfd(l4);
	return;
	}

	if (l4->l4_rsize) {
	n = l4->l4_rsize - l4->l4_rlen;
	ptr = l4->l4_rbuf + l4->l4_rlen;
	} else {
	n = sizeof(buf) - 1;
	ptr = buf;
	}

	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Read %d bytes on fd %d to %p\n",
	n, fd, ptr);
	i = recv(fd, ptr, n, 0);
	if (i == 0 \|\| i == -1) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Read error on fd %d: %s\n",
	fd, (i == 0) ? "EOF" : strerror(errno));
	closel4(l4, 1);
	} else {
	if (ptr == buf)
	ptr[i] = '\0';
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "%d: Read %d bytes [%.s]\n",
	fd, i, i, i, ptr);
	if (ptr != buf) {
	l4->l4_rlen += i;
	if (l4->l4_rlen >= l4->l4_rsize) {
	if (!strncmp(response, l4->l4_rbuf,
	l4->l4_rsize)) {
	printf("%d: Good response\n",
	fd);
	if (!l4->l4_alive) {
	l4->l4_alive = 1;
	addnat(l4);
	}
	closel4(l4, 0);
	} else {
	if (opts & OPT_VERBOSE)
	printf("%d: Bad response\n",
	fd);
	closel4(l4, 1);
	}
	}
	} else if (!l4->l4_alive) {
	l4->l4_alive = 1;
	addnat(l4);
	closel4(l4, 0);
	}
	}
	}


	int runconfig()
	{
	int fd, opt, res, mfd, i;
	struct timeval tv;
	time_t now, now1;
	fd_set rfd, wfd;
	l4cfg_t *l4;

	mfd = 0;
	opt = 1;
	now = time(NULL);

	/*
	* First, initiate connections that are closed, as required.
	*/
	for (l4 = l4list; l4; l4 = l4->l4_next) {
	if ((l4->l4_last + frequency < now) && (l4->l4_fd == -1)) {
	l4->l4_last = now;
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if (fd == -1)
	continue;
	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt,
	sizeof(opt));
	#ifdef O_NONBLOCK
	if ((res = fcntl(fd, F_GETFL, 0)) != -1)
	fcntl(fd, F_SETFL, res \| O_NONBLOCK);
	#endif
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"Connecting to %s,%d (fd %d)...",
	inet_ntoa(l4->l4_sin.sin_addr),
	ntohs(l4->l4_sin.sin_port), fd);
	if (connect(fd, (struct sockaddr *)&l4->l4_sin,
	sizeof(l4->l4_sin)) == -1) {
	if (errno != EINPROGRESS) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "failed\n");
	perror("connect");
	close(fd);
	fd = -1;
	} else {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "waiting\n");
	l4->l4_rw = -2;
	}
	} else {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "connected\n");
	connectl4(l4);
	}
	l4->l4_fd = fd;
	}
	}

	/*
	* Now look for fd's which we're expecting to read/write from.
	*/
	FD_ZERO(&rfd);
	FD_ZERO(&wfd);
	tv.tv_sec = MIN(rtimeout, ctimeout);
	tv.tv_usec = 0;

	for (l4 = l4list; l4; l4 = l4->l4_next)
	if (l4->l4_rw == 0) {
	if (now - l4->l4_last > rtimeout) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "%d: Read timeout\n",
	l4->l4_fd);
	closel4(l4, 1);
	continue;
	}
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Wait for read on fd %d\n",
	l4->l4_fd);
	FD_SET(l4->l4_fd, &rfd);
	if (l4->l4_fd > mfd)
	mfd = l4->l4_fd;
	} else if ((l4->l4_rw == 1 && l4->l4_wlen) \|\|
	l4->l4_rw == -2) {
	if ((l4->l4_rw == -2) &&
	(now - l4->l4_last > ctimeout)) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"%d: connect timeout\n",
	l4->l4_fd);
	closel4(l4);
	continue;
	}
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Wait for write on fd %d\n",
	l4->l4_fd);
	FD_SET(l4->l4_fd, &wfd);
	if (l4->l4_fd > mfd)
	mfd = l4->l4_fd;
	}

	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Select: max fd %d wait %d\n", mfd + 1,
	tv.tv_sec);
	i = select(mfd + 1, &rfd, &wfd, NULL, &tv);
	if (i == -1) {
	perror("select");
	return -1;
	}

	now1 = time(NULL);

	for (l4 = l4list; (i > 0) && l4; l4 = l4->l4_next) {
	if (l4->l4_fd < 0)
	continue;
	if (FD_ISSET(l4->l4_fd, &rfd)) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Ready to read on fd %d\n",
	l4->l4_fd);
	readfd(l4);
	i--;
	}

	if ((l4->l4_fd >= 0) && FD_ISSET(l4->l4_fd, &wfd)) {
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Ready to write on fd %d\n",
	l4->l4_fd);
	writefd(l4);
	i--;
	}
	}
	return 0;
	}


	int gethostport(str, lnum, ipp, portp)
	char *str;
	int lnum;
	u_32_t *ipp;
	u_short *portp;
	{
	struct servent *sp;
	struct hostent *hp;
	char host, port;
	struct in_addr ip;

	host = str;
	port = strchr(host, ',');
	if (port)
	*port++ = '\0';

	#ifdef HAVE_INET_ATON
	if (ISDIGIT(*host) && inet_aton(host, &ip))
	*ipp = ip.s_addr;
	#else
	if (ISDIGIT(*host))
	*ipp = inet_addr(host);
	#endif
	else {
	if (!(hp = gethostbyname(host))) {
	fprintf(stderr, "%d: can't resolve hostname: %s\n",
	lnum, host);
	return 0;
	}
	ipp = (u_32_t *)hp->h_addr;
	}

	if (port) {
	if (ISDIGIT(*port))
	*portp = htons(atoi(port));
	else {
	sp = getservbyname(port, "tcp");
	if (sp)
	*portp = sp->s_port;
	else {
	fprintf(stderr, "%d: unknown service %s\n",
	lnum, port);
	return 0;
	}
	}
	} else
	*portp = 0;
	return 1;
	}


	char *mapfile(file, sizep)
	char *file;
	size_t *sizep;
	{
	struct stat sb;
	caddr_t addr;
	int fd;

	fd = open(file, O_RDONLY);
	if (fd == -1) {
	perror("open(mapfile)");
	return NULL;
	}

	if (fstat(fd, &sb) == -1) {
	perror("fstat(mapfile)");
	close(fd);
	return NULL;
	}

	addr = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
	if (addr == (caddr_t)-1) {
	perror("mmap(mapfile)");
	close(fd);
	return NULL;
	}
	close(fd);
	*sizep = sb.st_size;
	return (char *)addr;
	}


	int readconfig(filename)
	char *filename;
	{
	char c, buf[512], s, t, errtxt = NULL, line;
	int num, err = 0;
	ipnat_t *ipn;
	l4cfg_t *l4;
	FILE *fp;

	fp = fopen(filename, "r");
	if (!fp) {
	perror("open(configfile)");
	return -1;
	}

	bzero((char *)&template, sizeof(template));
	template.l4_fd = -1;
	template.l4_rw = -1;
	template.l4_sin.sin_family = AF_INET;
	ipn = &template.l4_nat;
	ipn->in_flags = IPN_TCP\|IPN_ROUNDR;
	ipn->in_redir = NAT_REDIRECT;

	for (num = 1; fgets(buf, sizeof(buf), fp); num++) {
	s = strchr(buf, '\n');
	if (!s) {
	fprintf(stderr, "%d: line too long\n", num);
	fclose(fp);
	return -1;
	}

	*s = '\0';

	/*
	* lines which are comments
	*/
	s = strchr(buf, '#');
	if (s)
	*s = '\0';

	/*
	* Skip leading whitespace
	*/
	for (line = buf; (c = *line) && ISSPACE(c); line++)
	;
	if (!*line)
	continue;

	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Parsing: [%s]\n", line);
	t = strtok(line, " \t");
	if (!t)
	continue;
	if (!strcasecmp(t, "interface")) {
	s = strtok(NULL, " \t");
	if (s)
	t = strtok(NULL, "\t");
	if (!s \|\| !t) {
	errtxt = line;
	err = -1;
	break;
	}

	if (!strchr(t, ',')) {
	fprintf(stderr,
	"%d: local address,port missing\n",
	num);
	err = -1;
	break;
	}

	strncpy(ipn->in_ifname, s, sizeof(ipn->in_ifname));
	if (!gethostport(t, num, &ipn->in_outip,
	&ipn->in_pmin)) {
	errtxt = line;
	err = -1;
	break;
	}
	ipn->in_outmsk = 0xffffffff;
	ipn->in_pmax = ipn->in_pmin;
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"Interface %s %s/%#x port %u\n",
	ipn->in_ifname,
	inet_ntoa(ipn->in_out[0]),
	ipn->in_outmsk, ipn->in_pmin);
	} else if (!strcasecmp(t, "remote")) {
	if (!*ipn->in_ifname) {
	fprintf(stderr,
	"%d: ifname not set prior to remote\n",
	num);
	err = -1;
	break;
	}
	s = strtok(NULL, " \t");
	if (s)
	t = strtok(NULL, "");
	if (!s \|\| !t \|\| strcasecmp(s, "server")) {
	errtxt = line;
	err = -1;
	break;
	}

	ipn->in_pnext = 0;
	if (!gethostport(t, num, &ipn->in_inip,
	&ipn->in_pnext)) {
	errtxt = line;
	err = -1;
	break;
	}
	ipn->in_inmsk = 0xffffffff;
	if (ipn->in_pnext == 0)
	ipn->in_pnext = ipn->in_pmin;

	l4 = (l4cfg_t )malloc(sizeof(l4));
	if (!l4) {
	fprintf(stderr, "%d: out of memory (%d)\n",
	num, sizeof(*l4));
	err = -1;
	break;
	}
	bcopy((char )&template, (char )l4, sizeof(*l4));
	l4->l4_sin.sin_addr = ipn->in_in[0];
	l4->l4_sin.sin_port = ipn->in_pnext;
	l4->l4_next = l4list;
	l4list = l4;
	} else if (!strcasecmp(t, "connect")) {
	s = strtok(NULL, " \t");
	if (s)
	t = strtok(NULL, "\t");
	if (!s \|\| !t) {
	errtxt = line;
	err = -1;
	break;
	} else if (!strcasecmp(s, "timeout")) {
	ctimeout = atoi(t);
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "connect timeout %d\n",
	ctimeout);
	} else if (!strcasecmp(s, "frequency")) {
	frequency = atoi(t);
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"connect frequency %d\n",
	frequency);
	} else {
	errtxt = line;
	err = -1;
	break;
	}
	} else if (!strcasecmp(t, "probe")) {
	s = strtok(NULL, " \t");
	if (!s) {
	errtxt = line;
	err = -1;
	break;
	} else if (!strcasecmp(s, "string")) {
	if (probe) {
	fprintf(stderr,
	"%d: probe already set\n",
	num);
	err = -1;
	break;
	}
	t = strtok(NULL, "");
	if (!t) {
	fprintf(stderr,
	"%d: No probe string\n", num);
	err = -1;
	break;
	}

	probe = malloc(strlen(t));
	copystr(probe, t);
	plen = strlen(probe);
	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Probe string [%s]\n",
	probe);
	} else if (!strcasecmp(s, "file")) {
	t = strtok(NULL, " \t");
	if (!t) {
	errtxt = line;
	err = -1;
	break;
	}
	if (probe) {
	fprintf(stderr,
	"%d: probe already set\n",
	num);
	err = -1;
	break;
	}
	probe = mapfile(t, &plen);
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"Probe file %s len %u@%p\n",
	t, plen, probe);
	}
	} else if (!strcasecmp(t, "response")) {
	s = strtok(NULL, " \t");
	if (!s) {
	errtxt = line;
	err = -1;
	break;
	} else if (!strcasecmp(s, "timeout")) {
	t = strtok(NULL, " \t");
	if (!t) {
	errtxt = line;
	err = -1;
	break;
	}
	rtimeout = atoi(t);
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"response timeout %d\n",
	rtimeout);
	} else if (!strcasecmp(s, "string")) {
	if (response) {
	fprintf(stderr,
	"%d: response already set\n",
	num);
	err = -1;
	break;
	}
	response = strdup(strtok(NULL, ""));
	rlen = strlen(response);
	template.l4_rsize = rlen;
	template.l4_rbuf = malloc(rlen);
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"Response string [%s]\n",
	response);
	} else if (!strcasecmp(s, "file")) {
	t = strtok(NULL, " \t");
	if (!t) {
	errtxt = line;
	err = -1;
	break;
	}
	if (response) {
	fprintf(stderr,
	"%d: response already set\n",
	num);
	err = -1;
	break;
	}
	response = mapfile(t, &rlen);
	template.l4_rsize = rlen;
	template.l4_rbuf = malloc(rlen);
	if (opts & OPT_VERBOSE)
	fprintf(stderr,
	"Response file %s len %u@%p\n",
	t, rlen, response);
	}
	} else {
	errtxt = line;
	err = -1;
	break;
	}
	}

	if (errtxt)
	fprintf(stderr, "%d: syntax error at \"%s\"\n", num, errtxt);
	fclose(fp);
	return err;
	}


	void usage(prog)
	char *prog;
	{
	fprintf(stderr, "Usage: %s -f <configfile>\n", prog);
	exit(1);
	}


	int main(argc, argv)
	int argc;
	char *argv[];
	{
	char *config = NULL;
	int c;

	while ((c = getopt(argc, argv, "f:nv")) != -1)
	switch (c)
	{
	case 'f' :
	config = optarg;
	break;
	case 'n' :
	opts \|= OPT_DONOTHING;
	break;
	case 'v' :
	opts \|= OPT_VERBOSE;
	break;
	}

	if (config == NULL)
	usage(argv[0]);

	if (readconfig(config))
	exit(1);

	if (!l4list) {
	fprintf(stderr, "No remote servers, exiting.");
	exit(1);
	}

	if (!(opts & OPT_DONOTHING)) {
	natfd = open(IPL_NAT, O_RDWR);
	if (natfd == -1) {
	perror("open(IPL_NAT)");
	exit(1);
	}
	}

	if (opts & OPT_VERBOSE)
	fprintf(stderr, "Starting...\n");
	while (runconfig() == 0)
	;
	}