text: /*	$OpenBSD: filter.c,v 1.1 2005/12/28 19:07:07 jcs Exp $ */
  /*	$FreeBSD: soc2013/dpl/head/contrib/pf/tftp-proxy/filter.c 171215 2007-07-03 12:30:03Z mlaier $ */
  
  /*
   * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <syslog.h>
  
  #include <sys/ioctl.h>
  #include <sys/types.h>
  #include <sys/socket.h>
  
  #include <net/if.h>
  #include <net/pfvar.h>
  #include <netinet/in.h>
  #include <netinet/tcp.h>
  #include <arpa/inet.h>
  
  #include <err.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "filter.h"
  
  /* From netinet/in.h, but only _KERNEL_ gets them. */
  #define satosin(sa)	((struct sockaddr_in *)(sa))
  #define satosin6(sa)	((struct sockaddr_in6 *)(sa))
  
  enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
  
  int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
      u_int16_t, u_int8_t);
  int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
      struct sockaddr_in *, u_int8_t);
  int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
      struct sockaddr_in6 *, u_int8_t);
  
  static struct pfioc_pooladdr	pfp;
  static struct pfioc_rule	pfr;
  static struct pfioc_trans	pft;
  static struct pfioc_trans_e	pfte[TRANS_SIZE];
  static int dev, rule_log;
  static char *qname;
  
  int
  add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
      struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
  {
  	if (!src || !dst || !d_port || !proto) {
  		errno = EINVAL;
  		return (-1);
  	}
  
  	if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port, proto) == -1)
  		return (-1);
  
  	pfr.rule.direction = dir;
  	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
  		return (-1);
  
  	return (0);
  }
  
  int
  add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
      u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
      u_int16_t nat_range_high, u_int8_t proto)
  {
  	if (!src || !dst || !d_port || !nat || !nat_range_low || !proto ||
  	    (src->sa_family != nat->sa_family)) {
  		errno = EINVAL;
  		return (-1);
  	}
  
  	if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port, proto) == -1)
  		return (-1);
  
  	if (nat->sa_family == AF_INET) {
  		memcpy(&pfp.addr.addr.v.a.addr.v4,
  		    &satosin(nat)->sin_addr.s_addr, 4);
  		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
  	} else {
  		memcpy(&pfp.addr.addr.v.a.addr.v6,
  		    &satosin6(nat)->sin6_addr.s6_addr, 16);
  		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
  	}
  	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
  		return (-1);
  
  	pfr.rule.rpool.proxy_port[0] = nat_range_low;
  	pfr.rule.rpool.proxy_port[1] = nat_range_high;
  	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
  		return (-1);
  
  	return (0);
  }
  
  int
  add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
      u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port, u_int8_t proto)
  {
  	if (!src || !dst || !d_port || !rdr || !rdr_port || !proto ||
  	    (src->sa_family != rdr->sa_family)) {
  		errno = EINVAL;
  		return (-1);
  	}
  
  	if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port, proto) == -1)
  		return (-1);
  
  	if (rdr->sa_family == AF_INET) {
  		memcpy(&pfp.addr.addr.v.a.addr.v4,
  		    &satosin(rdr)->sin_addr.s_addr, 4);
  		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
  	} else {
  		memcpy(&pfp.addr.addr.v.a.addr.v6,
  		    &satosin6(rdr)->sin6_addr.s6_addr, 16);
  		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
  	}
  	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
  		return (-1);
  
  	pfr.rule.rpool.proxy_port[0] = rdr_port;
  	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
  		return (-1);
  
  	return (0);
  }
  
  int
  do_commit(void)
  {
  	if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
  		return (-1);
  
  	return (0);
  }
  
  int
  do_rollback(void)
  {
  	if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
  		return (-1);
  	
  	return (0);
  }
  
  void
  init_filter(char *opt_qname, int opt_verbose)
  {
  	struct pf_status status;
  
  	qname = opt_qname;
  
  	if (opt_verbose == 1)
  		rule_log = PF_LOG;
  	else if (opt_verbose == 2)
  		rule_log = PF_LOG_ALL;
  
  	dev = open("/dev/pf", O_RDWR);	
  	if (dev == -1) {
  		syslog(LOG_ERR, "can't open /dev/pf");
  		exit(1);
  	}
  	if (ioctl(dev, DIOCGETSTATUS, &status) == -1) {
  		syslog(LOG_ERR, "DIOCGETSTATUS");
  		exit(1);
  	}
  	if (!status.running) {
  		syslog(LOG_ERR, "pf is disabled");
  		exit(1);
  	}
  }
  
  int
  prepare_commit(u_int32_t id)
  {
  	char an[PF_ANCHOR_NAME_SIZE];
  	int i;
  
  	memset(&pft, 0, sizeof pft);
  	pft.size = TRANS_SIZE;
  	pft.esize = sizeof pfte[0];
  	pft.array = pfte;
  
  	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
  	    getpid(), id);
  	for (i = 0; i < TRANS_SIZE; i++) {
  		memset(&pfte[i], 0, sizeof pfte[0]);
  		strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
  		switch (i) {
  		case TRANS_FILTER:
  			pfte[i].rs_num = PF_RULESET_FILTER;
  			break;
  		case TRANS_NAT:
  			pfte[i].rs_num = PF_RULESET_NAT;
  			break;
  		case TRANS_RDR:
  			pfte[i].rs_num = PF_RULESET_RDR;
  			break;
  		default:
  			errno = EINVAL;
  			return (-1);
  		}
  	}
  
  	if (ioctl(dev, DIOCXBEGIN, &pft) == -1)
  		return (-1);
  
  	return (0);
  }
  	
  int
  prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
      struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
  {
  	char an[PF_ANCHOR_NAME_SIZE];
  
  	if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
  	    (src->sa_family != dst->sa_family)) {
  	    	errno = EPROTONOSUPPORT;
  		return (-1);
  	}
  
  	memset(&pfp, 0, sizeof pfp);
  	memset(&pfr, 0, sizeof pfr);
  	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
  	    getpid(), id);
  	strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
  	strlcpy(pfr.anchor, an, PF_ANCHOR_NAME_SIZE);
  
  	switch (rs_num) {
  	case PF_RULESET_FILTER:
  		pfr.ticket = pfte[TRANS_FILTER].ticket;
  		break;
  	case PF_RULESET_NAT:
  		pfr.ticket = pfte[TRANS_NAT].ticket;
  		break;
  	case PF_RULESET_RDR:
  		pfr.ticket = pfte[TRANS_RDR].ticket;
  		break;
  	default:
  		errno = EINVAL;
  		return (-1);
  	}
  	if (ioctl(dev, DIOCBEGINADDRS, &pfp) == -1)
  		return (-1);
  	pfr.pool_ticket = pfp.ticket;
  
  	/* Generic for all rule types. */
  	pfr.rule.af = src->sa_family;
  	pfr.rule.proto = proto;
  	pfr.rule.src.addr.type = PF_ADDR_ADDRMASK;
  	pfr.rule.dst.addr.type = PF_ADDR_ADDRMASK;
  	if (src->sa_family == AF_INET) {
  		memcpy(&pfr.rule.src.addr.v.a.addr.v4,
  		    &satosin(src)->sin_addr.s_addr, 4);
  		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 4);
  		memcpy(&pfr.rule.dst.addr.v.a.addr.v4,
  		    &satosin(dst)->sin_addr.s_addr, 4);
  		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 4);
  	} else {
  		memcpy(&pfr.rule.src.addr.v.a.addr.v6,
  		    &satosin6(src)->sin6_addr.s6_addr, 16);
  		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 16);
  		memcpy(&pfr.rule.dst.addr.v.a.addr.v6,
  		    &satosin6(dst)->sin6_addr.s6_addr, 16);
  		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 16);
  	}
  	pfr.rule.dst.port_op = PF_OP_EQ;
  	pfr.rule.dst.port[0] = htons(d_port);
  
  	switch (rs_num) {
  	case PF_RULESET_FILTER:
  		/*
  		 * pass quick [log] inet[6] proto tcp \
  		 *     from $src to $dst port = $d_port flags S/SAFR keep state
  		 *     (max 1) [queue qname]
  		 */
  		pfr.rule.action = PF_PASS;
  		pfr.rule.quick = 1;
  		pfr.rule.log = rule_log;
  		pfr.rule.keep_state = 1;
  #ifdef __FreeBSD__
  		pfr.rule.flags = (proto == IPPROTO_TCP ? TH_SYN : 0);
  		pfr.rule.flagset = (proto == IPPROTO_TCP ?
  		    (TH_SYN|TH_ACK|TH_FIN|TH_RST) : 0);
  #else
  		pfr.rule.flags = (proto == IPPROTO_TCP ? TH_SYN : NULL);
  		pfr.rule.flagset = (proto == IPPROTO_TCP ?
  		    (TH_SYN|TH_ACK|TH_FIN|TH_RST) : NULL);
  #endif
  		pfr.rule.max_states = 1;
  		if (qname != NULL)
  			strlcpy(pfr.rule.qname, qname, sizeof pfr.rule.qname);
  		break;
  	case PF_RULESET_NAT:
  		/*
  		 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
  		 */
  		pfr.rule.action = PF_NAT;
  		break;
  	case PF_RULESET_RDR:
  		/*
  		 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
  		 */
  		pfr.rule.action = PF_RDR;
  		break;
  	default:
  		errno = EINVAL;
  		return (-1);
  	}
  
  	return (0);
  }
  
  int
  server_lookup(struct sockaddr *client, struct sockaddr *proxy,
      struct sockaddr *server, u_int8_t proto)
  {
  	if (client->sa_family == AF_INET)
  		return (server_lookup4(satosin(client), satosin(proxy),
  		    satosin(server), proto));
  
  	if (client->sa_family == AF_INET6)
  		return (server_lookup6(satosin6(client), satosin6(proxy),
  		    satosin6(server), proto));
  
  	errno = EPROTONOSUPPORT;
  	return (-1);
  }
  
  int
  server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
      struct sockaddr_in *server, u_int8_t proto)
  {
  	struct pfioc_natlook pnl;
  
  	memset(&pnl, 0, sizeof pnl);
  	pnl.direction = PF_OUT;
  	pnl.af = AF_INET;
  	pnl.proto = proto;
  	memcpy(&pnl.saddr.v4, &client->sin_addr.s_addr, sizeof pnl.saddr.v4);
  	memcpy(&pnl.daddr.v4, &proxy->sin_addr.s_addr, sizeof pnl.daddr.v4);
  	pnl.sport = client->sin_port;
  	pnl.dport = proxy->sin_port;
  
  	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
  		return (-1);
  
  	memset(server, 0, sizeof(struct sockaddr_in));
  	server->sin_len = sizeof(struct sockaddr_in);
  	server->sin_family = AF_INET;
  	memcpy(&server->sin_addr.s_addr, &pnl.rdaddr.v4,
  	    sizeof server->sin_addr.s_addr);
  	server->sin_port = pnl.rdport;
  
  	return (0);
  }
  
  int
  server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
      struct sockaddr_in6 *server, u_int8_t proto)
  {
  	struct pfioc_natlook pnl;
  
  	memset(&pnl, 0, sizeof pnl);
  	pnl.direction = PF_OUT;
  	pnl.af = AF_INET6;
  	pnl.proto = proto;
  	memcpy(&pnl.saddr.v6, &client->sin6_addr.s6_addr, sizeof pnl.saddr.v6);
  	memcpy(&pnl.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof pnl.daddr.v6);
  	pnl.sport = client->sin6_port;
  	pnl.dport = proxy->sin6_port;
  	
  	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
  		return (-1);
  
  	memset(server, 0, sizeof(struct sockaddr_in6));
  	server->sin6_len = sizeof(struct sockaddr_in6);
  	server->sin6_family = AF_INET6;
  	memcpy(&server->sin6_addr.s6_addr, &pnl.rdaddr.v6,
  	    sizeof server->sin6_addr);
  	server->sin6_port = pnl.rdport;
  
  	return (0);
  }
  