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alias.c (61861) alias.c (63899)
1/* -*- mode: c; tab-width: 8; c-basic-indent: 4; -*- */
2/*
3 Alias.c provides supervisory control for the functions of the
4 packet aliasing software. It consists of routines to monitor
5 TCP connection state, protocol-specific aliasing routines,
6 fragment handling and the following outside world functional
7 interfaces: SaveFragmentPtr, GetFragmentPtr, FragmentAliasIn,
8 PacketAliasIn and PacketAliasOut.

--- 62 unchanged lines hidden (view full) ---

71 - Rationalized API function names to begin
72 with "PacketAlias..."
73 - Eliminated PacketAliasIn2() and
74 PacketAliasOut2() as poorly conceived.
75
76 Version 2.3 Dec 1998 (dillon)
77 - Major bounds checking additions, see FreeBSD/CVS
78
1/* -*- mode: c; tab-width: 8; c-basic-indent: 4; -*- */
2/*
3 Alias.c provides supervisory control for the functions of the
4 packet aliasing software. It consists of routines to monitor
5 TCP connection state, protocol-specific aliasing routines,
6 fragment handling and the following outside world functional
7 interfaces: SaveFragmentPtr, GetFragmentPtr, FragmentAliasIn,
8 PacketAliasIn and PacketAliasOut.

--- 62 unchanged lines hidden (view full) ---

71 - Rationalized API function names to begin
72 with "PacketAlias..."
73 - Eliminated PacketAliasIn2() and
74 PacketAliasOut2() as poorly conceived.
75
76 Version 2.3 Dec 1998 (dillon)
77 - Major bounds checking additions, see FreeBSD/CVS
78
79 Version 3.1 May, 2000 (eds)
79 Version 3.1 May, 2000 (salander)
80 - Added hooks to handle PPTP.
81
80 - Added hooks to handle PPTP.
81
82 Version 3.2 July, 2000 (salander and satoh)
83 - Added PacketUnaliasOut routine.
84 - Added hooks to handle RTSP/RTP.
85
82 See HISTORY file for additional revisions.
83
86 See HISTORY file for additional revisions.
87
84 $FreeBSD: head/sys/netinet/libalias/alias.c 61861 2000-06-20 11:41:48Z ru $
88 $FreeBSD: head/sys/netinet/libalias/alias.c 63899 2000-07-26 23:15:46Z archie $
85*/
86
87#include <sys/types.h>
88
89#include <netinet/in_systm.h>
90#include <netinet/in.h>
91#include <netinet/ip.h>
92#include <netinet/ip_icmp.h>

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97#include "alias.h"
98
99#define NETBIOS_NS_PORT_NUMBER 137
100#define NETBIOS_DGM_PORT_NUMBER 138
101#define FTP_CONTROL_PORT_NUMBER 21
102#define IRC_CONTROL_PORT_NUMBER_1 6667
103#define IRC_CONTROL_PORT_NUMBER_2 6668
104#define CUSEEME_PORT_NUMBER 7648
89*/
90
91#include <sys/types.h>
92
93#include <netinet/in_systm.h>
94#include <netinet/in.h>
95#include <netinet/ip.h>
96#include <netinet/ip_icmp.h>

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101#include "alias.h"
102
103#define NETBIOS_NS_PORT_NUMBER 137
104#define NETBIOS_DGM_PORT_NUMBER 138
105#define FTP_CONTROL_PORT_NUMBER 21
106#define IRC_CONTROL_PORT_NUMBER_1 6667
107#define IRC_CONTROL_PORT_NUMBER_2 6668
108#define CUSEEME_PORT_NUMBER 7648
109#define RTSP_CONTROL_PORT_NUMBER_1 554
110#define RTSP_CONTROL_PORT_NUMBER_2 7070
105#define PPTP_CONTROL_PORT_NUMBER 1723
106
107
108
109
110/* TCP Handling Routines
111
112 TcpMonitorIn() -- These routines monitor TCP connections, and

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1107
1108/* Special processing for IP encoding protocols */
1109 if (ntohs(tc->th_dport) == FTP_CONTROL_PORT_NUMBER
1110 || ntohs(tc->th_sport) == FTP_CONTROL_PORT_NUMBER)
1111 AliasHandleFtpOut(pip, link, maxpacketsize);
1112 else if (ntohs(tc->th_dport) == IRC_CONTROL_PORT_NUMBER_1
1113 || ntohs(tc->th_dport) == IRC_CONTROL_PORT_NUMBER_2)
1114 AliasHandleIrcOut(pip, link, maxpacketsize);
111#define PPTP_CONTROL_PORT_NUMBER 1723
112
113
114
115
116/* TCP Handling Routines
117
118 TcpMonitorIn() -- These routines monitor TCP connections, and

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1113
1114/* Special processing for IP encoding protocols */
1115 if (ntohs(tc->th_dport) == FTP_CONTROL_PORT_NUMBER
1116 || ntohs(tc->th_sport) == FTP_CONTROL_PORT_NUMBER)
1117 AliasHandleFtpOut(pip, link, maxpacketsize);
1118 else if (ntohs(tc->th_dport) == IRC_CONTROL_PORT_NUMBER_1
1119 || ntohs(tc->th_dport) == IRC_CONTROL_PORT_NUMBER_2)
1120 AliasHandleIrcOut(pip, link, maxpacketsize);
1121 else if (ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1
1122 || ntohs(tc->th_sport) == RTSP_CONTROL_PORT_NUMBER_1
1123 || ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2
1124 || ntohs(tc->th_sport) == RTSP_CONTROL_PORT_NUMBER_2)
1125 AliasHandleRtspOut(pip, link, maxpacketsize);
1115 else if (ntohs(tc->th_dport) == PPTP_CONTROL_PORT_NUMBER
1116 || ntohs(tc->th_sport) == PPTP_CONTROL_PORT_NUMBER)
1117 AliasHandlePptpOut(pip, link);
1118
1119/* Adjust TCP checksum since source port is being aliased */
1120/* and source address is being altered */
1121 accumulate = tc->th_sport;
1122 tc->th_sport = alias_port;

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1231
1232/* Outside World Access
1233
1234 PacketAliasSaveFragment()
1235 PacketAliasGetFragment()
1236 PacketAliasFragmentIn()
1237 PacketAliasIn()
1238 PacketAliasOut()
1126 else if (ntohs(tc->th_dport) == PPTP_CONTROL_PORT_NUMBER
1127 || ntohs(tc->th_sport) == PPTP_CONTROL_PORT_NUMBER)
1128 AliasHandlePptpOut(pip, link);
1129
1130/* Adjust TCP checksum since source port is being aliased */
1131/* and source address is being altered */
1132 accumulate = tc->th_sport;
1133 tc->th_sport = alias_port;

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1242
1243/* Outside World Access
1244
1245 PacketAliasSaveFragment()
1246 PacketAliasGetFragment()
1247 PacketAliasFragmentIn()
1248 PacketAliasIn()
1249 PacketAliasOut()
1250 PacketUnaliasOut()
1239
1240(prototypes in alias.h)
1241*/
1242
1243
1244int
1245PacketAliasSaveFragment(char *ptr)
1246{

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1460 else
1461 {
1462 iresult = FragmentOut(pip);
1463 }
1464
1465 SetDefaultAliasAddress(addr_save);
1466 return(iresult);
1467}
1251
1252(prototypes in alias.h)
1253*/
1254
1255
1256int
1257PacketAliasSaveFragment(char *ptr)
1258{

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1472 else
1473 {
1474 iresult = FragmentOut(pip);
1475 }
1476
1477 SetDefaultAliasAddress(addr_save);
1478 return(iresult);
1479}
1480
1481int
1482PacketUnaliasOut(char *ptr, /* valid IP packet */
1483 int maxpacketsize /* for error checking */
1484 )
1485{
1486 struct ip *pip;
1487 struct icmp *ic;
1488 struct udphdr *ud;
1489 struct tcphdr *tc;
1490 struct alias_link *link;
1491 int iresult = PKT_ALIAS_IGNORED;
1492
1493 pip = (struct ip *) ptr;
1494
1495 /* Defense against mangled packets */
1496 if (ntohs(pip->ip_len) > maxpacketsize
1497 || (pip->ip_hl<<2) > maxpacketsize)
1498 return(iresult);
1499
1500 ud = (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
1501 tc = (struct tcphdr *) ud;
1502 ic = (struct icmp *) ud;
1503
1504 /* Find a link */
1505 if (pip->ip_p == IPPROTO_UDP)
1506 link = QueryUdpTcpIn(pip->ip_dst, pip->ip_src,
1507 ud->uh_dport, ud->uh_sport,
1508 IPPROTO_UDP);
1509 else if (pip->ip_p == IPPROTO_TCP)
1510 link = QueryUdpTcpIn(pip->ip_dst, pip->ip_src,
1511 tc->th_dport, tc->th_sport,
1512 IPPROTO_TCP);
1513 else if (pip->ip_p == IPPROTO_ICMP)
1514 link = FindIcmpIn(pip->ip_dst, pip->ip_src, ic->icmp_id);
1515 else
1516 link = NULL;
1517
1518 /* Change it from an aliased packet to an unaliased packet */
1519 if (link != NULL)
1520 {
1521 if (pip->ip_p == IPPROTO_UDP || pip->ip_p == IPPROTO_TCP)
1522 {
1523 u_short *sptr;
1524 int accumulate;
1525 struct in_addr original_address;
1526 u_short original_port;
1527
1528 original_address = GetOriginalAddress(link);
1529 original_port = GetOriginalPort(link);
1530
1531 /* Adjust TCP/UDP checksum */
1532 sptr = (u_short *) &(pip->ip_src);
1533 accumulate = *sptr++;
1534 accumulate += *sptr;
1535 sptr = (u_short *) &original_address;
1536 accumulate -= *sptr++;
1537 accumulate -= *sptr;
1538
1539 if (pip->ip_p == IPPROTO_UDP) {
1540 accumulate += ud->uh_sport;
1541 accumulate -= original_port;
1542 ADJUST_CHECKSUM(accumulate, ud->uh_sum)
1543 } else {
1544 accumulate += tc->th_sport;
1545 accumulate -= original_port;
1546 ADJUST_CHECKSUM(accumulate, tc->th_sum)
1547 }
1548
1549 /* Adjust IP checksum */
1550 DifferentialChecksum(&pip->ip_sum,
1551 (u_short *) &original_address,
1552 (u_short *) &pip->ip_src,
1553 2);
1554
1555 /* Un-alias source address and port number */
1556 pip->ip_src = original_address;
1557 if (pip->ip_p == IPPROTO_UDP)
1558 ud->uh_sport = original_port;
1559 else
1560 tc->th_sport = original_port;
1561
1562 iresult = PKT_ALIAS_OK;
1563
1564 } else if (pip->ip_p == IPPROTO_ICMP) {
1565
1566 u_short *sptr;
1567 int accumulate;
1568 struct in_addr original_address;
1569 u_short original_id;
1570
1571 original_address = GetOriginalAddress(link);
1572 original_id = GetOriginalPort(link);
1573
1574 /* Adjust ICMP checksum */
1575 sptr = (u_short *) &(pip->ip_src);
1576 accumulate = *sptr++;
1577 accumulate += *sptr;
1578 sptr = (u_short *) &original_address;
1579 accumulate -= *sptr++;
1580 accumulate -= *sptr;
1581 accumulate += ic->icmp_id;
1582 accumulate -= original_id;
1583 ADJUST_CHECKSUM(accumulate, ic->icmp_cksum)
1584
1585 /* Adjust IP checksum */
1586 DifferentialChecksum(&pip->ip_sum,
1587 (u_short *) &original_address,
1588 (u_short *) &pip->ip_src,
1589 2);
1590
1591 /* Un-alias source address and port number */
1592 pip->ip_src = original_address;
1593 ic->icmp_id = original_id;
1594
1595 iresult = PKT_ALIAS_OK;
1596 }
1597 }
1598 return(iresult);
1599
1600}