2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
33 Alias.c provides supervisory control for the functions of the
34 packet aliasing software. It consists of routines to monitor
35 TCP connection state, protocol-specific aliasing routines,
36 fragment handling and the following outside world functional
37 interfaces: SaveFragmentPtr, GetFragmentPtr, FragmentAliasIn,
38 PacketAliasIn and PacketAliasOut.
40 The other C program files are briefly described. The data
41 structure framework which holds information needed to translate
42 packets is encapsulated in alias_db.c. Data is accessed by
43 function calls, so other segments of the program need not know
44 about the underlying data structures. Alias_ftp.c contains
45 special code for modifying the ftp PORT command used to establish
46 data connections, while alias_irc.c does the same for IRC
47 DCC. Alias_util.c contains a few utility routines.
49 Version 1.0 August, 1996 (cjm)
51 Version 1.1 August 20, 1996 (cjm)
52 PPP host accepts incoming connections for ports 0 to 1023.
53 (Gary Roberts pointed out the need to handle incoming
56 Version 1.2 September 7, 1996 (cjm)
57 Fragment handling error in alias_db.c corrected.
58 (Tom Torrance helped fix this problem.)
60 Version 1.4 September 16, 1996 (cjm)
61 - A more generalized method for handling incoming
62 connections, without the 0-1023 restriction, is
63 implemented in alias_db.c
64 - Improved ICMP support in alias.c. Traceroute
65 packet streams can now be correctly aliased.
66 - TCP connection closing logic simplified in
67 alias.c and now allows for additional 1 minute
68 "grace period" after FIN or RST is observed.
70 Version 1.5 September 17, 1996 (cjm)
71 Corrected error in handling incoming UDP packets with 0 checksum.
72 (Tom Torrance helped fix this problem.)
74 Version 1.6 September 18, 1996 (cjm)
75 Simplified ICMP aliasing scheme. Should now support
76 traceroute from Win95 as well as FreeBSD.
78 Version 1.7 January 9, 1997 (cjm)
79 - Out-of-order fragment handling.
80 - IP checksum error fixed for ftp transfers
82 - Integer return codes added to all
83 aliasing/de-aliasing functions.
84 - Some obsolete comments cleaned up.
85 - Differential checksum computations for
86 IP header (TCP, UDP and ICMP were already
89 Version 2.1 May 1997 (cjm)
90 - Added support for outgoing ICMP error
92 - Added two functions PacketAliasIn2()
93 and PacketAliasOut2() for dynamic address
94 control (e.g. round-robin allocation of
97 Version 2.2 July 1997 (cjm)
98 - Rationalized API function names to begin
100 - Eliminated PacketAliasIn2() and
101 PacketAliasOut2() as poorly conceived.
103 Version 2.3 Dec 1998 (dillon)
104 - Major bounds checking additions, see FreeBSD/CVS
106 Version 3.1 May, 2000 (salander)
107 - Added hooks to handle PPTP.
109 Version 3.2 July, 2000 (salander and satoh)
110 - Added PacketUnaliasOut routine.
111 - Added hooks to handle RTSP/RTP.
113 See HISTORY file for additional revisions.
117 #include <sys/param.h>
118 #include <sys/systm.h>
119 #include <sys/mbuf.h>
120 #include <sys/sysctl.h>
122 #include <sys/types.h>
131 #include <netinet/in_systm.h>
132 #include <netinet/in.h>
133 #include <netinet/ip.h>
134 #include <netinet/ip_icmp.h>
135 #include <netinet/tcp.h>
136 #include <netinet/udp.h>
139 #include <netinet/libalias/alias.h>
140 #include <netinet/libalias/alias_local.h>
141 #include <netinet/libalias/alias_mod.h>
145 #include "alias_local.h"
146 #include "alias_mod.h"
150 * Define libalias SYSCTL Node
154 SYSCTL_DECL(_net_inet);
155 SYSCTL_DECL(_net_inet_ip);
156 SYSCTL_NODE(_net_inet_ip, OID_AUTO, alias, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
157 "Libalias sysctl API");
166 #if BYTE_ORDER == LITTLE_ENDIAN
167 uint16_t s1 = ((uint16_t)c[1] << 8) + (uint16_t)c[0];
168 uint16_t s2 = ((uint16_t)c[3] << 8) + (uint16_t)c[2];
170 uint16_t s1 = ((uint16_t)c[0] << 8) + (uint16_t)c[1];
171 uint16_t s2 = ((uint16_t)c[2] << 8) + (uint16_t)c[3];
176 /* TCP Handling Routines
178 TcpMonitorIn() -- These routines monitor TCP connections, and
179 TcpMonitorOut() delete a link when a connection is closed.
181 These routines look for SYN, FIN and RST flags to determine when TCP
182 connections open and close. When a TCP connection closes, the data
183 structure containing packet aliasing information is deleted after
187 /* Local prototypes */
188 static void TcpMonitorIn(u_char, struct alias_link *);
190 static void TcpMonitorOut(u_char, struct alias_link *);
193 TcpMonitorIn(u_char th_flags, struct alias_link *lnk)
195 switch (GetStateIn(lnk)) {
196 case ALIAS_TCP_STATE_NOT_CONNECTED:
197 if (th_flags & TH_RST)
198 SetStateIn(lnk, ALIAS_TCP_STATE_DISCONNECTED);
199 else if (th_flags & TH_SYN)
200 SetStateIn(lnk, ALIAS_TCP_STATE_CONNECTED);
202 case ALIAS_TCP_STATE_CONNECTED:
203 if (th_flags & (TH_FIN | TH_RST))
204 SetStateIn(lnk, ALIAS_TCP_STATE_DISCONNECTED);
210 TcpMonitorOut(u_char th_flags, struct alias_link *lnk)
212 switch (GetStateOut(lnk)) {
213 case ALIAS_TCP_STATE_NOT_CONNECTED:
214 if (th_flags & TH_RST)
215 SetStateOut(lnk, ALIAS_TCP_STATE_DISCONNECTED);
216 else if (th_flags & TH_SYN)
217 SetStateOut(lnk, ALIAS_TCP_STATE_CONNECTED);
219 case ALIAS_TCP_STATE_CONNECTED:
220 if (th_flags & (TH_FIN | TH_RST))
221 SetStateOut(lnk, ALIAS_TCP_STATE_DISCONNECTED);
226 /* Protocol Specific Packet Aliasing Routines
228 IcmpAliasIn(), IcmpAliasIn1(), IcmpAliasIn2()
229 IcmpAliasOut(), IcmpAliasOut1(), IcmpAliasOut2()
230 ProtoAliasIn(), ProtoAliasOut()
231 UdpAliasIn(), UdpAliasOut()
232 TcpAliasIn(), TcpAliasOut()
234 These routines handle protocol specific details of packet aliasing.
235 One may observe a certain amount of repetitive arithmetic in these
236 functions, the purpose of which is to compute a revised checksum
237 without actually summing over the entire data packet, which could be
238 unnecessarily time consuming.
240 The purpose of the packet aliasing routines is to replace the source
241 address of the outgoing packet and then correctly put it back for
242 any incoming packets. For TCP and UDP, ports are also re-mapped.
244 For ICMP echo/timestamp requests and replies, the following scheme
245 is used: the ID number is replaced by an alias for the outgoing
248 ICMP error messages are handled by looking at the IP fragment
249 in the data section of the message.
251 For TCP and UDP protocols, a port number is chosen for an outgoing
252 packet, and then incoming packets are identified by IP address and
253 port numbers. For TCP packets, there is additional logic in the event
254 that sequence and ACK numbers have been altered (as in the case for
255 FTP data port commands).
257 The port numbers used by the packet aliasing module are not true
258 ports in the Unix sense. No sockets are actually bound to ports.
259 They are more correctly thought of as placeholders.
261 All packets go through the aliasing mechanism, whether they come from
262 the gateway machine or other machines on a local area network.
265 /* Local prototypes */
266 static int IcmpAliasIn1(struct libalias *, struct ip *);
267 static int IcmpAliasIn2(struct libalias *, struct ip *);
268 static int IcmpAliasIn(struct libalias *, struct ip *);
270 static int IcmpAliasOut1(struct libalias *, struct ip *, int create);
271 static int IcmpAliasOut2(struct libalias *, struct ip *);
272 static int IcmpAliasOut(struct libalias *, struct ip *, int create);
274 static int ProtoAliasIn(struct libalias *la, struct in_addr ip_src,
275 struct ip *pip, u_char ip_p, u_short *ip_sum);
276 static int ProtoAliasOut(struct libalias *la, struct ip *pip,
277 struct in_addr ip_dst, u_char ip_p, u_short *ip_sum,
280 static int UdpAliasIn(struct libalias *, struct ip *);
281 static int UdpAliasOut(struct libalias *, struct ip *, int, int create);
283 static int TcpAliasIn(struct libalias *, struct ip *);
284 static int TcpAliasOut(struct libalias *, struct ip *, int, int create);
287 De-alias incoming echo and timestamp replies.
288 Alias incoming echo and timestamp requests.
291 IcmpAliasIn1(struct libalias *la, struct ip *pip)
293 struct alias_link *lnk;
296 LIBALIAS_LOCK_ASSERT(la);
297 ic = (struct icmp *)ip_next(pip);
299 /* Get source address from ICMP data field and restore original data */
300 lnk = FindIcmpIn(la, pip->ip_src, pip->ip_dst, ic->icmp_id, 1);
305 original_id = GetOriginalPort(lnk);
307 /* Adjust ICMP checksum */
308 accumulate = ic->icmp_id;
309 accumulate -= original_id;
310 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);
312 /* Put original sequence number back in */
313 ic->icmp_id = original_id;
315 /* Put original address back into IP header */
317 struct in_addr original_address;
319 original_address = GetOriginalAddress(lnk);
320 DifferentialChecksum(&pip->ip_sum,
321 &original_address, &pip->ip_dst, 2);
322 pip->ip_dst = original_address;
325 return (PKT_ALIAS_OK);
327 return (PKT_ALIAS_IGNORED);
331 Alias incoming ICMP error messages containing
332 IP header and first 64 bits of datagram.
335 IcmpAliasIn2(struct libalias *la, struct ip *pip)
338 struct icmp *ic, *ic2;
341 struct alias_link *lnk;
343 LIBALIAS_LOCK_ASSERT(la);
344 ic = (struct icmp *)ip_next(pip);
347 ud = (struct udphdr *)ip_next(ip);
348 tc = (struct tcphdr *)ip_next(ip);
349 ic2 = (struct icmp *)ip_next(ip);
351 if (ip->ip_p == IPPROTO_UDP)
352 lnk = FindUdpTcpIn(la, ip->ip_dst, ip->ip_src,
353 ud->uh_dport, ud->uh_sport,
355 else if (ip->ip_p == IPPROTO_TCP)
356 lnk = FindUdpTcpIn(la, ip->ip_dst, ip->ip_src,
357 tc->th_dport, tc->th_sport,
359 else if (ip->ip_p == IPPROTO_ICMP) {
360 if (ic2->icmp_type == ICMP_ECHO || ic2->icmp_type == ICMP_TSTAMP)
361 lnk = FindIcmpIn(la, ip->ip_dst, ip->ip_src, ic2->icmp_id, 0);
368 if (ip->ip_p == IPPROTO_UDP || ip->ip_p == IPPROTO_TCP) {
369 int accumulate, accumulate2;
370 struct in_addr original_address;
371 u_short original_port;
373 original_address = GetOriginalAddress(lnk);
374 original_port = GetOriginalPort(lnk);
376 /* Adjust ICMP checksum */
377 accumulate = twowords(&ip->ip_src);
378 accumulate -= twowords(&original_address);
379 accumulate += ud->uh_sport;
380 accumulate -= original_port;
381 accumulate2 = accumulate;
382 accumulate2 += ip->ip_sum;
383 ADJUST_CHECKSUM(accumulate, ip->ip_sum);
384 accumulate2 -= ip->ip_sum;
385 ADJUST_CHECKSUM(accumulate2, ic->icmp_cksum);
387 /* Un-alias address in IP header */
388 DifferentialChecksum(&pip->ip_sum,
389 &original_address, &pip->ip_dst, 2);
390 pip->ip_dst = original_address;
392 /* Un-alias address and port number of
393 * original IP packet fragment contained
394 * in ICMP data section */
395 ip->ip_src = original_address;
396 ud->uh_sport = original_port;
397 } else if (ip->ip_p == IPPROTO_ICMP) {
398 int accumulate, accumulate2;
399 struct in_addr original_address;
402 original_address = GetOriginalAddress(lnk);
403 original_id = GetOriginalPort(lnk);
405 /* Adjust ICMP checksum */
406 accumulate = twowords(&ip->ip_src);
407 accumulate -= twowords(&original_address);
408 accumulate += ic2->icmp_id;
409 accumulate -= original_id;
410 accumulate2 = accumulate;
411 accumulate2 += ip->ip_sum;
412 ADJUST_CHECKSUM(accumulate, ip->ip_sum);
413 accumulate2 -= ip->ip_sum;
414 ADJUST_CHECKSUM(accumulate2, ic->icmp_cksum);
416 /* Un-alias address in IP header */
417 DifferentialChecksum(&pip->ip_sum,
418 &original_address, &pip->ip_dst, 2);
419 pip->ip_dst = original_address;
421 /* Un-alias address of original IP packet and
422 * sequence number of embedded ICMP datagram */
423 ip->ip_src = original_address;
424 ic2->icmp_id = original_id;
426 return (PKT_ALIAS_OK);
428 return (PKT_ALIAS_IGNORED);
432 IcmpAliasIn(struct libalias *la, struct ip *pip)
438 LIBALIAS_LOCK_ASSERT(la);
440 dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
441 if (dlen < ICMP_MINLEN)
442 return (PKT_ALIAS_IGNORED);
444 /* Return if proxy-only mode is enabled */
445 if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY)
446 return (PKT_ALIAS_OK);
448 ic = (struct icmp *)ip_next(pip);
450 iresult = PKT_ALIAS_IGNORED;
451 switch (ic->icmp_type) {
453 case ICMP_TSTAMPREPLY:
454 if (ic->icmp_code == 0) {
455 iresult = IcmpAliasIn1(la, pip);
459 case ICMP_SOURCEQUENCH:
462 if (dlen < ICMP_ADVLENMIN ||
463 dlen < (size_t)ICMP_ADVLEN(ic))
464 return (PKT_ALIAS_IGNORED);
465 iresult = IcmpAliasIn2(la, pip);
469 iresult = IcmpAliasIn1(la, pip);
476 Alias outgoing echo and timestamp requests.
477 De-alias outgoing echo and timestamp replies.
480 IcmpAliasOut1(struct libalias *la, struct ip *pip, int create)
482 struct alias_link *lnk;
485 LIBALIAS_LOCK_ASSERT(la);
486 ic = (struct icmp *)ip_next(pip);
488 /* Save overwritten data for when echo packet returns */
489 lnk = FindIcmpOut(la, pip->ip_src, pip->ip_dst, ic->icmp_id, create);
494 alias_id = GetAliasPort(lnk);
496 /* Since data field is being modified, adjust ICMP checksum */
497 accumulate = ic->icmp_id;
498 accumulate -= alias_id;
499 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);
501 /* Alias sequence number */
502 ic->icmp_id = alias_id;
504 /* Change source address */
506 struct in_addr alias_address;
508 alias_address = GetAliasAddress(lnk);
509 DifferentialChecksum(&pip->ip_sum,
510 &alias_address, &pip->ip_src, 2);
511 pip->ip_src = alias_address;
514 return (PKT_ALIAS_OK);
516 return (PKT_ALIAS_IGNORED);
520 Alias outgoing ICMP error messages containing
521 IP header and first 64 bits of datagram.
524 IcmpAliasOut2(struct libalias *la, struct ip *pip)
527 struct icmp *ic, *ic2;
530 struct alias_link *lnk;
532 LIBALIAS_LOCK_ASSERT(la);
533 ic = (struct icmp *)ip_next(pip);
536 ud = (struct udphdr *)ip_next(ip);
537 tc = (struct tcphdr *)ip_next(ip);
538 ic2 = (struct icmp *)ip_next(ip);
540 if (ip->ip_p == IPPROTO_UDP)
541 lnk = FindUdpTcpOut(la, ip->ip_dst, ip->ip_src,
542 ud->uh_dport, ud->uh_sport,
544 else if (ip->ip_p == IPPROTO_TCP)
545 lnk = FindUdpTcpOut(la, ip->ip_dst, ip->ip_src,
546 tc->th_dport, tc->th_sport,
548 else if (ip->ip_p == IPPROTO_ICMP) {
549 if (ic2->icmp_type == ICMP_ECHO || ic2->icmp_type == ICMP_TSTAMP)
550 lnk = FindIcmpOut(la, ip->ip_dst, ip->ip_src, ic2->icmp_id, 0);
557 if (ip->ip_p == IPPROTO_UDP || ip->ip_p == IPPROTO_TCP) {
559 struct in_addr alias_address;
562 alias_address = GetAliasAddress(lnk);
563 alias_port = GetAliasPort(lnk);
565 /* Adjust ICMP checksum */
566 accumulate = twowords(&ip->ip_dst);
567 accumulate -= twowords(&alias_address);
568 accumulate += ud->uh_dport;
569 accumulate -= alias_port;
570 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);
573 * Alias address in IP header if it comes from the host
574 * the original TCP/UDP packet was destined for.
576 if (pip->ip_src.s_addr == ip->ip_dst.s_addr) {
577 DifferentialChecksum(&pip->ip_sum,
578 &alias_address, &pip->ip_src, 2);
579 pip->ip_src = alias_address;
581 /* Alias address and port number of original IP packet
582 * fragment contained in ICMP data section */
583 ip->ip_dst = alias_address;
584 ud->uh_dport = alias_port;
585 } else if (ip->ip_p == IPPROTO_ICMP) {
587 struct in_addr alias_address;
590 alias_address = GetAliasAddress(lnk);
591 alias_id = GetAliasPort(lnk);
593 /* Adjust ICMP checksum */
594 accumulate = twowords(&ip->ip_dst);
595 accumulate -= twowords(&alias_address);
596 accumulate += ic2->icmp_id;
597 accumulate -= alias_id;
598 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);
601 * Alias address in IP header if it comes from the host
602 * the original ICMP message was destined for.
604 if (pip->ip_src.s_addr == ip->ip_dst.s_addr) {
605 DifferentialChecksum(&pip->ip_sum,
606 &alias_address, &pip->ip_src, 2);
607 pip->ip_src = alias_address;
609 /* Alias address of original IP packet and
610 * sequence number of embedded ICMP datagram */
611 ip->ip_dst = alias_address;
612 ic2->icmp_id = alias_id;
614 return (PKT_ALIAS_OK);
616 return (PKT_ALIAS_IGNORED);
620 IcmpAliasOut(struct libalias *la, struct ip *pip, int create)
625 LIBALIAS_LOCK_ASSERT(la);
628 /* Return if proxy-only mode is enabled */
629 if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY)
630 return (PKT_ALIAS_OK);
632 ic = (struct icmp *)ip_next(pip);
634 iresult = PKT_ALIAS_IGNORED;
635 switch (ic->icmp_type) {
638 if (ic->icmp_code == 0) {
639 iresult = IcmpAliasOut1(la, pip, create);
643 case ICMP_SOURCEQUENCH:
646 iresult = IcmpAliasOut2(la, pip);
649 case ICMP_TSTAMPREPLY:
650 iresult = IcmpAliasOut1(la, pip, create);
656 Handle incoming IP packets. The
657 only thing which is done in this case is to alias
658 the dest IP address of the packet to our inside
662 ProtoAliasIn(struct libalias *la, struct in_addr ip_src,
663 struct ip *pip, u_char ip_p, u_short *ip_sum)
665 struct alias_link *lnk;
667 LIBALIAS_LOCK_ASSERT(la);
668 /* Return if proxy-only mode is enabled */
669 if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY)
670 return (PKT_ALIAS_OK);
672 lnk = FindProtoIn(la, ip_src, pip->ip_dst, ip_p);
674 struct in_addr original_address;
676 original_address = GetOriginalAddress(lnk);
678 /* Restore original IP address */
679 DifferentialChecksum(ip_sum,
680 &original_address, &pip->ip_dst, 2);
681 pip->ip_dst = original_address;
683 return (PKT_ALIAS_OK);
685 return (PKT_ALIAS_IGNORED);
689 Handle outgoing IP packets. The
690 only thing which is done in this case is to alias
691 the source IP address of the packet.
694 ProtoAliasOut(struct libalias *la, struct ip *pip,
695 struct in_addr ip_dst, u_char ip_p, u_short *ip_sum, int create)
697 struct alias_link *lnk;
699 LIBALIAS_LOCK_ASSERT(la);
701 /* Return if proxy-only mode is enabled */
702 if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY)
703 return (PKT_ALIAS_OK);
706 return (PKT_ALIAS_IGNORED);
708 lnk = FindProtoOut(la, pip->ip_src, ip_dst, ip_p);
710 struct in_addr alias_address;
712 alias_address = GetAliasAddress(lnk);
714 /* Change source address */
715 DifferentialChecksum(ip_sum,
716 &alias_address, &pip->ip_src, 2);
717 pip->ip_src = alias_address;
719 return (PKT_ALIAS_OK);
721 return (PKT_ALIAS_IGNORED);
724 #define MF_ISSET(_pip) (ntohs((_pip)->ip_off) & IP_MF)
725 #define FRAG_NO_HDR(_pip) (ntohs((_pip)->ip_off) & IP_OFFMASK)
727 static struct udphdr *
728 ValidateUdpLength(struct ip *pip)
734 KASSERT(!FRAG_NO_HDR(pip), ("header-less fragment isn't expected here"));
736 dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
737 if (dlen < sizeof(struct udphdr))
739 ud = (struct udphdr *)ip_next(pip);
740 if (!MF_ISSET(pip) && dlen < ntohs(ud->uh_ulen))
746 UdpAliasIn(struct libalias *la, struct ip *pip)
749 struct alias_link *lnk;
751 LIBALIAS_LOCK_ASSERT(la);
753 ud = ValidateUdpLength(pip);
755 return (PKT_ALIAS_IGNORED);
757 lnk = FindUdpTcpIn(la, pip->ip_src, pip->ip_dst,
758 ud->uh_sport, ud->uh_dport,
759 IPPROTO_UDP, !(la->packetAliasMode & PKT_ALIAS_PROXY_ONLY));
761 struct in_addr alias_address;
762 struct in_addr original_address;
763 struct in_addr proxy_address;
768 struct alias_data ad = {
770 .oaddr = &original_address,
771 .aaddr = &alias_address,
772 .aport = &alias_port,
773 .sport = &ud->uh_sport,
774 .dport = &ud->uh_dport,
778 alias_address = GetAliasAddress(lnk);
779 original_address = GetOriginalAddress(lnk);
780 proxy_address = GetProxyAddress(lnk);
781 alias_port = ud->uh_dport;
782 ud->uh_dport = GetOriginalPort(lnk);
783 proxy_port = GetProxyPort(lnk);
785 /* Walk out chain. */
786 error = find_handler(IN, UDP, la, pip, &ad);
787 /* If we cannot figure out the packet, ignore it. */
789 return (PKT_ALIAS_IGNORED);
791 /* If UDP checksum is not zero, then adjust since
792 * destination port is being unaliased and
793 * destination address is being altered. */
794 if (ud->uh_sum != 0) {
795 accumulate = alias_port;
796 accumulate -= ud->uh_dport;
797 accumulate += twowords(&alias_address);
798 accumulate -= twowords(&original_address);
800 /* If this is a proxy packet, modify checksum
801 * because of source change.*/
802 if (proxy_port != 0) {
803 accumulate += ud->uh_sport;
804 accumulate -= proxy_port;
807 if (proxy_address.s_addr != 0) {
808 accumulate += twowords(&pip->ip_src);
809 accumulate -= twowords(&proxy_address);
812 ADJUST_CHECKSUM(accumulate, ud->uh_sum);
815 /* XXX: Could the two if's below be concatenated to one ? */
816 /* Restore source port and/or address in case of proxying*/
818 ud->uh_sport = proxy_port;
820 if (proxy_address.s_addr != 0) {
821 DifferentialChecksum(&pip->ip_sum,
822 &proxy_address, &pip->ip_src, 2);
823 pip->ip_src = proxy_address;
826 /* Restore original IP address */
827 DifferentialChecksum(&pip->ip_sum,
828 &original_address, &pip->ip_dst, 2);
829 pip->ip_dst = original_address;
831 return (PKT_ALIAS_OK);
833 return (PKT_ALIAS_IGNORED);
837 UdpAliasOut(struct libalias *la, struct ip *pip, int maxpacketsize, int create)
840 struct alias_link *lnk;
841 struct in_addr dest_address;
842 struct in_addr proxy_server_address;
844 u_short proxy_server_port;
847 LIBALIAS_LOCK_ASSERT(la);
849 ud = ValidateUdpLength(pip);
851 return (PKT_ALIAS_IGNORED);
853 /* Return if proxy-only mode is enabled and not proxyrule found.*/
854 proxy_type = ProxyCheck(la, &proxy_server_address, &proxy_server_port,
855 pip->ip_src, pip->ip_dst, ud->uh_dport, pip->ip_p);
856 if (proxy_type == 0 && (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY))
857 return (PKT_ALIAS_OK);
859 /* If this is a transparent proxy, save original destination,
860 * then alter the destination and adjust checksums */
861 dest_port = ud->uh_dport;
862 dest_address = pip->ip_dst;
864 if (proxy_type != 0) {
867 accumulate = twowords(&pip->ip_dst);
868 accumulate -= twowords(&proxy_server_address);
870 ADJUST_CHECKSUM(accumulate, pip->ip_sum);
872 if (ud->uh_sum != 0) {
873 accumulate = twowords(&pip->ip_dst);
874 accumulate -= twowords(&proxy_server_address);
875 accumulate += ud->uh_dport;
876 accumulate -= proxy_server_port;
877 ADJUST_CHECKSUM(accumulate, ud->uh_sum);
879 pip->ip_dst = proxy_server_address;
880 ud->uh_dport = proxy_server_port;
882 lnk = FindUdpTcpOut(la, pip->ip_src, pip->ip_dst,
883 ud->uh_sport, ud->uh_dport,
884 IPPROTO_UDP, create);
887 struct in_addr alias_address;
888 struct alias_data ad = {
891 .aaddr = &alias_address,
892 .aport = &alias_port,
893 .sport = &ud->uh_sport,
894 .dport = &ud->uh_dport,
898 /* Save original destination address, if this is a proxy packet.
899 * Also modify packet to include destination encoding. This may
900 * change the size of IP header. */
901 if (proxy_type != 0) {
902 SetProxyPort(lnk, dest_port);
903 SetProxyAddress(lnk, dest_address);
904 ProxyModify(la, lnk, pip, maxpacketsize, proxy_type);
905 ud = (struct udphdr *)ip_next(pip);
908 alias_address = GetAliasAddress(lnk);
909 alias_port = GetAliasPort(lnk);
911 /* Walk out chain. */
912 find_handler(OUT, UDP, la, pip, &ad);
914 /* If UDP checksum is not zero, adjust since source port is */
915 /* being aliased and source address is being altered */
916 if (ud->uh_sum != 0) {
919 accumulate = ud->uh_sport;
920 accumulate -= alias_port;
921 accumulate += twowords(&pip->ip_src);
922 accumulate -= twowords(&alias_address);
923 ADJUST_CHECKSUM(accumulate, ud->uh_sum);
925 /* Put alias port in UDP header */
926 ud->uh_sport = alias_port;
928 /* Change source address */
929 DifferentialChecksum(&pip->ip_sum,
930 &alias_address, &pip->ip_src, 2);
931 pip->ip_src = alias_address;
933 return (PKT_ALIAS_OK);
935 return (PKT_ALIAS_IGNORED);
939 TcpAliasIn(struct libalias *la, struct ip *pip)
942 struct alias_link *lnk;
945 LIBALIAS_LOCK_ASSERT(la);
947 dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
948 if (dlen < sizeof(struct tcphdr))
949 return (PKT_ALIAS_IGNORED);
950 tc = (struct tcphdr *)ip_next(pip);
952 lnk = FindUdpTcpIn(la, pip->ip_src, pip->ip_dst,
953 tc->th_sport, tc->th_dport,
955 !(la->packetAliasMode & PKT_ALIAS_PROXY_ONLY));
957 struct in_addr alias_address;
958 struct in_addr original_address;
959 struct in_addr proxy_address;
965 * The init of MANY vars is a bit below, but aliashandlepptpin
966 * seems to need the destination port that came within the
967 * packet and not the original one looks below [*].
970 struct alias_data ad = {
975 .sport = &tc->th_sport,
976 .dport = &tc->th_dport,
980 /* Walk out chain. */
981 find_handler(IN, TCP, la, pip, &ad);
983 alias_address = GetAliasAddress(lnk);
984 original_address = GetOriginalAddress(lnk);
985 proxy_address = GetProxyAddress(lnk);
986 alias_port = tc->th_dport;
987 tc->th_dport = GetOriginalPort(lnk);
988 proxy_port = GetProxyPort(lnk);
991 * Look above, if anyone is going to add find_handler AFTER
992 * this aliashandlepptpin/point, please redo alias_data too.
993 * Uncommenting the piece here below should be enough.
996 struct alias_data ad = {
998 .oaddr = &original_address,
999 .aaddr = &alias_address,
1000 .aport = &alias_port,
1001 .sport = &ud->uh_sport,
1002 .dport = &ud->uh_dport,
1006 /* Walk out chain. */
1007 error = find_handler(la, pip, &ad);
1008 if (error == EHDNOF)
1009 printf("Protocol handler not found\n");
1012 /* Adjust TCP checksum since destination port is being
1013 * unaliased and destination port is being altered. */
1014 accumulate = alias_port;
1015 accumulate -= tc->th_dport;
1016 accumulate += twowords(&alias_address);
1017 accumulate -= twowords(&original_address);
1019 /* If this is a proxy, then modify the TCP source port
1020 * and checksum accumulation */
1021 if (proxy_port != 0) {
1022 accumulate += tc->th_sport;
1023 tc->th_sport = proxy_port;
1024 accumulate -= tc->th_sport;
1025 accumulate += twowords(&pip->ip_src);
1026 accumulate -= twowords(&proxy_address);
1028 /* See if ACK number needs to be modified */
1029 if (GetAckModified(lnk) == 1) {
1032 tc = (struct tcphdr *)ip_next(pip);
1033 delta = GetDeltaAckIn(tc->th_ack, lnk);
1035 accumulate += twowords(&tc->th_ack);
1036 tc->th_ack = htonl(ntohl(tc->th_ack) - delta);
1037 accumulate -= twowords(&tc->th_ack);
1040 ADJUST_CHECKSUM(accumulate, tc->th_sum);
1042 /* Restore original IP address */
1043 accumulate = twowords(&pip->ip_dst);
1044 pip->ip_dst = original_address;
1045 accumulate -= twowords(&pip->ip_dst);
1047 /* If this is a transparent proxy packet,
1048 * then modify the source address */
1049 if (proxy_address.s_addr != 0) {
1050 accumulate += twowords(&pip->ip_src);
1051 pip->ip_src = proxy_address;
1052 accumulate -= twowords(&pip->ip_src);
1054 ADJUST_CHECKSUM(accumulate, pip->ip_sum);
1056 /* Monitor TCP connection state */
1057 tc = (struct tcphdr *)ip_next(pip);
1058 TcpMonitorIn(tc->th_flags, lnk);
1060 return (PKT_ALIAS_OK);
1062 return (PKT_ALIAS_IGNORED);
1066 TcpAliasOut(struct libalias *la, struct ip *pip, int maxpacketsize, int create)
1070 u_short proxy_server_port;
1072 struct in_addr dest_address;
1073 struct in_addr proxy_server_address;
1075 struct alias_link *lnk;
1077 LIBALIAS_LOCK_ASSERT(la);
1079 dlen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
1080 if (dlen < sizeof(struct tcphdr))
1081 return (PKT_ALIAS_IGNORED);
1082 tc = (struct tcphdr *)ip_next(pip);
1085 proxy_type = ProxyCheck(la, &proxy_server_address,
1086 &proxy_server_port, pip->ip_src, pip->ip_dst,
1087 tc->th_dport, pip->ip_p);
1091 if (proxy_type == 0 && (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY))
1092 return (PKT_ALIAS_OK);
1094 /* If this is a transparent proxy, save original destination,
1095 * then alter the destination and adjust checksums */
1096 dest_port = tc->th_dport;
1097 dest_address = pip->ip_dst;
1098 if (proxy_type != 0) {
1101 accumulate = tc->th_dport;
1102 tc->th_dport = proxy_server_port;
1103 accumulate -= tc->th_dport;
1104 accumulate += twowords(&pip->ip_dst);
1105 accumulate -= twowords(&proxy_server_address);
1106 ADJUST_CHECKSUM(accumulate, tc->th_sum);
1108 accumulate = twowords(&pip->ip_dst);
1109 pip->ip_dst = proxy_server_address;
1110 accumulate -= twowords(&pip->ip_dst);
1111 ADJUST_CHECKSUM(accumulate, pip->ip_sum);
1113 lnk = FindUdpTcpOut(la, pip->ip_src, pip->ip_dst,
1114 tc->th_sport, tc->th_dport,
1115 IPPROTO_TCP, create);
1117 return (PKT_ALIAS_IGNORED);
1120 struct in_addr alias_address;
1122 struct alias_data ad = {
1125 .aaddr = &alias_address,
1126 .aport = &alias_port,
1127 .sport = &tc->th_sport,
1128 .dport = &tc->th_dport,
1129 .maxpktsize = maxpacketsize
1132 /* Save original destination address, if this is a proxy packet.
1133 * Also modify packet to include destination
1134 * encoding. This may change the size of IP header. */
1135 if (proxy_type != 0) {
1136 SetProxyPort(lnk, dest_port);
1137 SetProxyAddress(lnk, dest_address);
1138 ProxyModify(la, lnk, pip, maxpacketsize, proxy_type);
1139 tc = (struct tcphdr *)ip_next(pip);
1141 /* Get alias address and port */
1142 alias_port = GetAliasPort(lnk);
1143 alias_address = GetAliasAddress(lnk);
1145 /* Monitor TCP connection state */
1146 tc = (struct tcphdr *)ip_next(pip);
1147 TcpMonitorOut(tc->th_flags, lnk);
1149 /* Walk out chain. */
1150 find_handler(OUT, TCP, la, pip, &ad);
1152 /* Adjust TCP checksum since source port is being aliased
1153 * and source address is being altered */
1154 accumulate = tc->th_sport;
1155 tc->th_sport = alias_port;
1156 accumulate -= tc->th_sport;
1157 accumulate += twowords(&pip->ip_src);
1158 accumulate -= twowords(&alias_address);
1160 /* Modify sequence number if necessary */
1161 if (GetAckModified(lnk) == 1) {
1164 tc = (struct tcphdr *)ip_next(pip);
1165 delta = GetDeltaSeqOut(tc->th_seq, lnk);
1167 accumulate += twowords(&tc->th_seq);
1168 tc->th_seq = htonl(ntohl(tc->th_seq) + delta);
1169 accumulate -= twowords(&tc->th_seq);
1172 ADJUST_CHECKSUM(accumulate, tc->th_sum);
1174 /* Change source address */
1175 accumulate = twowords(&pip->ip_src);
1176 pip->ip_src = alias_address;
1177 accumulate -= twowords(&pip->ip_src);
1178 ADJUST_CHECKSUM(accumulate, pip->ip_sum);
1180 return (PKT_ALIAS_OK);
1182 return (PKT_ALIAS_IGNORED);
1185 /* Fragment Handling
1190 The packet aliasing module has a limited ability for handling IP
1191 fragments. If the ICMP, TCP or UDP header is in the first fragment
1192 received, then the ID number of the IP packet is saved, and other
1193 fragments are identified according to their ID number and IP address
1194 they were sent from. Pointers to unresolved fragments can also be
1195 saved and recalled when a header fragment is seen.
1198 /* Local prototypes */
1199 static int FragmentIn(struct libalias *la, struct in_addr ip_src,
1200 struct ip *pip, u_short ip_id, u_short *ip_sum);
1201 static int FragmentOut(struct libalias *, struct ip *pip,
1205 FragmentIn(struct libalias *la, struct in_addr ip_src, struct ip *pip,
1206 u_short ip_id, u_short *ip_sum)
1208 struct alias_link *lnk;
1210 LIBALIAS_LOCK_ASSERT(la);
1211 lnk = FindFragmentIn2(la, ip_src, pip->ip_dst, ip_id);
1213 struct in_addr original_address;
1215 GetFragmentAddr(lnk, &original_address);
1216 DifferentialChecksum(ip_sum,
1217 &original_address, &pip->ip_dst, 2);
1218 pip->ip_dst = original_address;
1220 return (PKT_ALIAS_OK);
1222 return (PKT_ALIAS_UNRESOLVED_FRAGMENT);
1226 FragmentOut(struct libalias *la, struct ip *pip, u_short *ip_sum)
1228 struct in_addr alias_address;
1230 LIBALIAS_LOCK_ASSERT(la);
1231 alias_address = FindAliasAddress(la, pip->ip_src);
1232 DifferentialChecksum(ip_sum,
1233 &alias_address, &pip->ip_src, 2);
1234 pip->ip_src = alias_address;
1236 return (PKT_ALIAS_OK);
1239 /* Outside World Access
1241 PacketAliasSaveFragment()
1242 PacketAliasGetFragment()
1243 PacketAliasFragmentIn()
1248 (prototypes in alias.h)
1252 LibAliasSaveFragment(struct libalias *la, void *ptr)
1255 struct alias_link *lnk;
1259 pip = (struct ip *)ptr;
1260 lnk = AddFragmentPtrLink(la, pip->ip_src, pip->ip_id);
1261 iresult = PKT_ALIAS_ERROR;
1263 SetFragmentPtr(lnk, ptr);
1264 iresult = PKT_ALIAS_OK;
1266 LIBALIAS_UNLOCK(la);
1271 LibAliasGetFragment(struct libalias *la, void *ptr)
1273 struct alias_link *lnk;
1278 pip = (struct ip *)ptr;
1279 lnk = FindFragmentPtr(la, pip->ip_src, pip->ip_id);
1281 GetFragmentPtr(lnk, &fptr);
1282 SetFragmentPtr(lnk, NULL);
1283 SetExpire(lnk, 0); /* Deletes link */
1287 LIBALIAS_UNLOCK(la);
1292 LibAliasFragmentIn(struct libalias *la,
1293 void *ptr, /* Points to correctly de-aliased header fragment */
1294 void *ptr_fragment /* fragment which must be de-aliased */
1302 pip = (struct ip *)ptr;
1303 fpip = (struct ip *)ptr_fragment;
1305 DifferentialChecksum(&fpip->ip_sum,
1306 &pip->ip_dst, &fpip->ip_dst, 2);
1307 fpip->ip_dst = pip->ip_dst;
1308 LIBALIAS_UNLOCK(la);
1311 /* Local prototypes */
1313 LibAliasOutLocked(struct libalias *la, struct ip *pip,
1314 int maxpacketsize, int create);
1316 LibAliasInLocked(struct libalias *la, struct ip *pip,
1320 LibAliasIn(struct libalias *la, void *ptr, int maxpacketsize)
1325 res = LibAliasInLocked(la, (struct ip *)ptr, maxpacketsize);
1326 LIBALIAS_UNLOCK(la);
1331 LibAliasInLocked(struct libalias *la, struct ip *pip, int maxpacketsize)
1333 struct in_addr alias_addr;
1336 if (la->packetAliasMode & PKT_ALIAS_REVERSE) {
1337 la->packetAliasMode &= ~PKT_ALIAS_REVERSE;
1338 iresult = LibAliasOutLocked(la, pip, maxpacketsize, 1);
1339 la->packetAliasMode |= PKT_ALIAS_REVERSE;
1343 alias_addr = pip->ip_dst;
1345 /* Defense against mangled packets */
1346 if (ntohs(pip->ip_len) > maxpacketsize
1347 || (pip->ip_hl << 2) > maxpacketsize) {
1348 iresult = PKT_ALIAS_IGNORED;
1352 if (FRAG_NO_HDR(pip)) {
1353 iresult = FragmentIn(la, pip->ip_src, pip, pip->ip_id,
1358 iresult = PKT_ALIAS_IGNORED;
1359 switch (pip->ip_p) {
1361 iresult = IcmpAliasIn(la, pip);
1364 iresult = UdpAliasIn(la, pip);
1367 iresult = TcpAliasIn(la, pip);
1371 iresult = SctpAlias(la, pip, SN_TO_LOCAL);
1376 struct alias_data ad = {
1386 /* Walk out chain. */
1387 error = find_handler(IN, IP, la, pip, &ad);
1389 iresult = PKT_ALIAS_OK;
1391 iresult = ProtoAliasIn(la, pip->ip_src,
1392 pip, pip->ip_p, &pip->ip_sum);
1396 iresult = ProtoAliasIn(la, pip->ip_src, pip,
1397 pip->ip_p, &pip->ip_sum);
1401 if (MF_ISSET(pip)) {
1402 struct alias_link *lnk;
1404 lnk = FindFragmentIn1(la, pip->ip_src, alias_addr, pip->ip_id);
1406 iresult = PKT_ALIAS_FOUND_HEADER_FRAGMENT;
1407 SetFragmentAddr(lnk, pip->ip_dst);
1409 iresult = PKT_ALIAS_ERROR;
1417 /* Unregistered address ranges */
1419 /* 10.0.0.0 -> 10.255.255.255 */
1420 #define UNREG_ADDR_A_LOWER 0x0a000000
1421 #define UNREG_ADDR_A_UPPER 0x0affffff
1423 /* 172.16.0.0 -> 172.31.255.255 */
1424 #define UNREG_ADDR_B_LOWER 0xac100000
1425 #define UNREG_ADDR_B_UPPER 0xac1fffff
1427 /* 192.168.0.0 -> 192.168.255.255 */
1428 #define UNREG_ADDR_C_LOWER 0xc0a80000
1429 #define UNREG_ADDR_C_UPPER 0xc0a8ffff
1431 /* 100.64.0.0 -> 100.127.255.255 (RFC 6598 - Carrier Grade NAT) */
1432 #define UNREG_ADDR_CGN_LOWER 0x64400000
1433 #define UNREG_ADDR_CGN_UPPER 0x647fffff
1436 LibAliasOut(struct libalias *la, void *ptr, int maxpacketsize)
1441 res = LibAliasOutLocked(la, (struct ip *)ptr, maxpacketsize, 1);
1442 LIBALIAS_UNLOCK(la);
1447 LibAliasOutTry(struct libalias *la, void *ptr, int maxpacketsize, int create)
1452 res = LibAliasOutLocked(la, (struct ip *)ptr, maxpacketsize, create);
1453 LIBALIAS_UNLOCK(la);
1458 LibAliasOutLocked(struct libalias *la,
1459 struct ip *pip, /* valid IP packet */
1460 int maxpacketsize, /* How much the packet data may grow (FTP and IRC inline changes) */
1461 int create /* Create new entries ? */
1465 struct in_addr addr_save;
1467 if (la->packetAliasMode & PKT_ALIAS_REVERSE) {
1468 la->packetAliasMode &= ~PKT_ALIAS_REVERSE;
1469 iresult = LibAliasInLocked(la, pip, maxpacketsize);
1470 la->packetAliasMode |= PKT_ALIAS_REVERSE;
1475 /* Defense against mangled packets */
1476 if (ntohs(pip->ip_len) > maxpacketsize
1477 || (pip->ip_hl << 2) > maxpacketsize) {
1478 iresult = PKT_ALIAS_IGNORED;
1482 addr_save = GetDefaultAliasAddress(la);
1483 if (la->packetAliasMode & PKT_ALIAS_UNREGISTERED_ONLY ||
1484 la->packetAliasMode & PKT_ALIAS_UNREGISTERED_CGN) {
1489 addr = ntohl(pip->ip_src.s_addr);
1490 if (addr >= UNREG_ADDR_C_LOWER && addr <= UNREG_ADDR_C_UPPER)
1492 else if (addr >= UNREG_ADDR_B_LOWER && addr <= UNREG_ADDR_B_UPPER)
1494 else if (addr >= UNREG_ADDR_A_LOWER && addr <= UNREG_ADDR_A_UPPER)
1496 else if (addr >= UNREG_ADDR_CGN_LOWER && addr <= UNREG_ADDR_CGN_UPPER &&
1497 la->packetAliasMode & PKT_ALIAS_UNREGISTERED_CGN)
1501 SetDefaultAliasAddress(la, pip->ip_src);
1503 } else if (la->packetAliasMode & PKT_ALIAS_PROXY_ONLY) {
1504 SetDefaultAliasAddress(la, pip->ip_src);
1507 if (FRAG_NO_HDR(pip)) {
1508 iresult = FragmentOut(la, pip, &pip->ip_sum);
1509 goto getout_restore;
1512 iresult = PKT_ALIAS_IGNORED;
1513 switch (pip->ip_p) {
1515 iresult = IcmpAliasOut(la, pip, create);
1518 iresult = UdpAliasOut(la, pip, maxpacketsize, create);
1521 iresult = TcpAliasOut(la, pip, maxpacketsize, create);
1525 iresult = SctpAlias(la, pip, SN_TO_GLOBAL);
1530 struct alias_data ad = {
1539 /* Walk out chain. */
1540 error = find_handler(OUT, IP, la, pip, &ad);
1542 iresult = PKT_ALIAS_OK;
1544 iresult = ProtoAliasOut(la, pip,
1545 pip->ip_dst, pip->ip_p, &pip->ip_sum, create);
1549 iresult = ProtoAliasOut(la, pip,
1550 pip->ip_dst, pip->ip_p, &pip->ip_sum, create);
1555 SetDefaultAliasAddress(la, addr_save);
1561 LibAliasUnaliasOut(struct libalias *la,
1562 void *ptr, /* valid IP packet */
1563 int maxpacketsize /* for error checking */
1570 struct alias_link *lnk;
1571 int iresult = PKT_ALIAS_IGNORED;
1574 pip = (struct ip *)ptr;
1576 /* Defense against mangled packets */
1577 if (ntohs(pip->ip_len) > maxpacketsize
1578 || (pip->ip_hl << 2) > maxpacketsize)
1581 ud = (struct udphdr *)ip_next(pip);
1582 tc = (struct tcphdr *)ip_next(pip);
1583 ic = (struct icmp *)ip_next(pip);
1586 if (pip->ip_p == IPPROTO_UDP)
1587 lnk = FindUdpTcpIn(la, pip->ip_dst, pip->ip_src,
1588 ud->uh_dport, ud->uh_sport,
1590 else if (pip->ip_p == IPPROTO_TCP)
1591 lnk = FindUdpTcpIn(la, pip->ip_dst, pip->ip_src,
1592 tc->th_dport, tc->th_sport,
1594 else if (pip->ip_p == IPPROTO_ICMP)
1595 lnk = FindIcmpIn(la, pip->ip_dst, pip->ip_src, ic->icmp_id, 0);
1599 /* Change it from an aliased packet to an unaliased packet */
1601 if (pip->ip_p == IPPROTO_UDP || pip->ip_p == IPPROTO_TCP) {
1603 struct in_addr original_address;
1604 u_short original_port;
1606 original_address = GetOriginalAddress(lnk);
1607 original_port = GetOriginalPort(lnk);
1609 /* Adjust TCP/UDP checksum */
1610 accumulate = twowords(&pip->ip_src);
1611 accumulate -= twowords(&original_address);
1613 if (pip->ip_p == IPPROTO_UDP) {
1614 accumulate += ud->uh_sport;
1615 accumulate -= original_port;
1616 ADJUST_CHECKSUM(accumulate, ud->uh_sum);
1618 accumulate += tc->th_sport;
1619 accumulate -= original_port;
1620 ADJUST_CHECKSUM(accumulate, tc->th_sum);
1623 /* Adjust IP checksum */
1624 DifferentialChecksum(&pip->ip_sum,
1625 &original_address, &pip->ip_src, 2);
1627 /* Un-alias source address and port number */
1628 pip->ip_src = original_address;
1629 if (pip->ip_p == IPPROTO_UDP)
1630 ud->uh_sport = original_port;
1632 tc->th_sport = original_port;
1634 iresult = PKT_ALIAS_OK;
1635 } else if (pip->ip_p == IPPROTO_ICMP) {
1637 struct in_addr original_address;
1638 u_short original_id;
1640 original_address = GetOriginalAddress(lnk);
1641 original_id = GetOriginalPort(lnk);
1643 /* Adjust ICMP checksum */
1644 accumulate = twowords(&pip->ip_src);
1645 accumulate -= twowords(&original_address);
1646 accumulate += ic->icmp_id;
1647 accumulate -= original_id;
1648 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);
1650 /* Adjust IP checksum */
1651 DifferentialChecksum(&pip->ip_sum,
1652 &original_address, &pip->ip_src, 2);
1654 /* Un-alias source address and port number */
1655 pip->ip_src = original_address;
1656 ic->icmp_id = original_id;
1658 iresult = PKT_ALIAS_OK;
1662 LIBALIAS_UNLOCK(la);
1669 LibAliasRefreshModules(void)
1671 char buf[256], conf[] = "/etc/libalias.conf";
1675 fd = fopen(conf, "r");
1677 err(1, "fopen(%s)", conf);
1679 LibAliasUnLoadAllModule();
1682 fgets(buf, 256, fd);
1687 for (i = 0; i < len; i++)
1688 if (!isspace(buf[i]))
1692 buf[len - 1] = '\0';
1693 LibAliasLoadModule(buf);
1701 LibAliasLoadModule(char *path)
1705 struct proto_handler *m;
1709 handle = dlopen (path, RTLD_LAZY);
1711 fprintf(stderr, "%s\n", dlerror());
1715 p = dlsym(handle, "alias_mod");
1716 if ((error = dlerror()) != NULL) {
1717 fprintf(stderr, "%s\n", dlerror());
1721 t = malloc(sizeof(struct dll));
1724 strncpy(t->name, p->name, DLL_LEN);
1726 if (attach_dll(t) == EEXIST) {
1728 fprintf(stderr, "dll conflict\n");
1732 m = dlsym(t->handle, "handlers");
1733 if ((error = dlerror()) != NULL) {
1734 fprintf(stderr, "%s\n", error);
1738 LibAliasAttachHandlers(m);
1743 LibAliasUnLoadAllModule(void)
1746 struct proto_handler *p;
1748 /* Unload all modules then reload everything. */
1749 while ((p = first_handler()) != NULL) {
1750 LibAliasDetachHandlers(p);
1752 while ((t = walk_dll_chain()) != NULL) {
1763 * m_megapullup() - this function is a big hack.
1764 * Thankfully, it's only used in ng_nat and ipfw+nat.
1766 * It allocates an mbuf with cluster and copies the specified part of the chain
1767 * into cluster, so that it is all contiguous and can be accessed via a plain
1768 * (char *) pointer. This is required, because libalias doesn't know how to
1769 * handle mbuf chains.
1771 * On success, m_megapullup returns an mbuf (possibly with cluster) containing
1772 * the input packet, on failure NULL. The input packet is always consumed.
1775 m_megapullup(struct mbuf *m, int len)
1779 if (len > m->m_pkthdr.len)
1782 if (m->m_next == NULL && M_WRITABLE(m))
1785 if (len <= MJUMPAGESIZE)
1786 mcl = m_get2(len, M_NOWAIT, MT_DATA, M_PKTHDR);
1787 else if (len <= MJUM9BYTES)
1788 mcl = m_getjcl(M_NOWAIT, MT_DATA, M_PKTHDR, MJUM9BYTES);
1789 else if (len <= MJUM16BYTES)
1790 mcl = m_getjcl(M_NOWAIT, MT_DATA, M_PKTHDR, MJUM16BYTES);
1796 m_move_pkthdr(mcl, m);
1797 m_copydata(m, 0, len, mtod(mcl, caddr_t));
1798 mcl->m_len = mcl->m_pkthdr.len = len;