1941 lines
50 KiB
C
1941 lines
50 KiB
C
/* -*- mode: c; tab-width: 8; c-basic-indent: 4; -*-
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Alias_db.c encapsulates all data structures used for storing
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packet aliasing data. Other parts of the aliasing software
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access data through functions provided in this file.
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Data storage is based on the notion of a "link", which is
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established for ICMP echo/reply packets, UDP datagrams and
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TCP stream connections. A link stores the original source
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and destination addresses. For UDP and TCP, it also stores
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source and destination port numbers, as well as an alias
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port number. Links are also used to store information about
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fragments.
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There is a facility for sweeping through and deleting old
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links as new packets are sent through. A simple timeout is
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used for ICMP and UDP links. TCP links are left alone unless
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there is an incomplete connection, in which case the link
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can be deleted after a certain amount of time.
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This software is placed into the public domain with no restrictions
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on its distribution.
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Initial version: August, 1996 (cjm)
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Version 1.4: September 16, 1996 (cjm)
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Facility for handling incoming links added.
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Version 1.6: September 18, 1996 (cjm)
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ICMP data handling simplified.
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Version 1.7: January 9, 1997 (cjm)
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Fragment handling simplified.
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Saves pointers for unresolved fragments.
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Permits links for unspecied remote ports
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or unspecified remote addresses.
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Fixed bug which did not properly zero port
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table entries after a link was deleted.
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Cleaned up some obsolete comments.
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Version 1.8: January 14, 1997 (cjm)
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Fixed data type error in StartPoint().
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(This error did not exist prior to v1.7
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and was discovered and fixed by Ari Suutari)
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Version 1.9: February 1, 1997
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Optionally, connections initiated from packet aliasing host
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machine will will not have their port number aliased unless it
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conflicts with an aliasing port already being used. (cjm)
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All options earlier being #ifdef'ed now are available through
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a new interface, SetPacketAliasMode(). This allow run time
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control (which is now available in PPP+pktAlias through the
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'alias' keyword). (ee)
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Added ability to create an alias port without
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either destination address or port specified.
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port type = ALIAS_PORT_UNKNOWN_DEST_ALL (ee)
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Removed K&R style function headers
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and general cleanup. (ee)
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Added packetAliasMode to replace compiler #defines's (ee)
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Allocates sockets for partially specified
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ports if ALIAS_USE_SOCKETS defined. (cjm)
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Version 2.0: March, 1997
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SetAliasAddress() will now clean up alias links
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if the aliasing address is changed. (cjm)
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PacketAliasPermanentLink() function added to support permanent
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links. (J. Fortes suggested the need for this.)
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Examples:
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(192.168.0.1, port 23) <-> alias port 6002, unknown dest addr/port
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(192.168.0.2, port 21) <-> alias port 3604, known dest addr
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unknown dest port
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These permament links allow for incoming connections to
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machines on the local network. They can be given with a
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user-chosen amount of specificity, with increasing specificity
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meaning more security. (cjm)
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Quite a bit of rework to the basic engine. The portTable[]
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array, which kept track of which ports were in use was replaced
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by a table/linked list structure. (cjm)
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SetExpire() function added. (cjm)
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DeleteLink() no longer frees memory association with a pointer
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to a fragment (this bug was first recognized by E. Eiklund in
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v1.9).
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Version 2.1: May, 1997 (cjm)
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Packet aliasing engine reworked so that it can handle
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multiple external addresses rather than just a single
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host address.
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PacketAliasRedirectPort() and PacketAliasRedirectAddr()
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added to the API. The first function is a more generalized
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version of PacketAliasPermanentLink(). The second function
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implements static network address translation.
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*/
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/* System include files */
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/errno.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <sys/types.h>
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/* BSD network include files */
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#include <netinet/in_systm.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#include <netinet/tcp.h>
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#include <arpa/inet.h>
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#include "alias.h"
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#include "alias_local.h"
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/*
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Constants (note: constants are also defined
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near relevant functions or structs)
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*/
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/* Sizes of input and output link tables */
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#define LINK_TABLE_OUT_SIZE 101
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#define LINK_TABLE_IN_SIZE 4001
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/* Parameters used for cleanup of expired links */
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#define ALIAS_CLEANUP_INTERVAL_SECS 60
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#define ALIAS_CLEANUP_MAX_SPOKES 30
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/* Timouts (in seconds) for different link types) */
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#define ICMP_EXPIRE_TIME 60
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#define UDP_EXPIRE_TIME 60
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#define TCP_EXPIRE_TIME 90
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#define FRAGMENT_ID_EXPIRE_TIME 10
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#define FRAGMENT_PTR_EXPIRE_TIME 30
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/* Dummy port number codes used for FindLinkIn/Out() and AddLink().
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These constants can be anything except zero, which indicates an
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unknown port numbea. */
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#define NO_DEST_PORT 1
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#define NO_SRC_PORT 1
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/* Data Structures
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The fundamental data structure used in this program is
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"struct alias_link". Whenever a TCP connection is made,
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a UDP datagram is sent out, or an ICMP echo request is made,
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a link record is made (if it has not already been created).
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The link record is identified by the source address/port
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and the destination address/port. In the case of an ICMP
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echo request, the source port is treated as being equivalent
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with the 16-bit id number of the ICMP packet.
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The link record also can store some auxiliary data. For
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TCP connections that have had sequence and acknowledgment
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modifications, data space is available to track these changes.
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A state field is used to keep track in changes to the tcp
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connection state. Id numbers of fragments can also be
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stored in the auxiliary space. Pointers to unresolved
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framgents can also be stored.
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The link records support two independent chainings. Lookup
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tables for input and out tables hold the initial pointers
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the link chains. On input, the lookup table indexes on alias
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port and link type. On output, the lookup table indexes on
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source addreess, destination address, source port, destination
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port and link type.
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*/
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struct ack_data_record /* used to save changes to ack/seq numbers */
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{
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u_long ack_old;
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u_long ack_new;
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int delta;
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int active;
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};
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struct tcp_state /* Information about tcp connection */
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{
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int in; /* State for outside -> inside */
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int out; /* State for inside -> outside */
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int index; /* Index to ack data array */
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int ack_modified; /* Indicates whether ack and seq numbers */
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/* been modified */
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};
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#define N_LINK_TCP_DATA 3 /* Number of distinct ack number changes
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saved for a modified TCP stream */
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struct tcp_dat
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{
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struct tcp_state state;
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struct ack_data_record ack[N_LINK_TCP_DATA];
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};
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struct alias_link /* Main data structure */
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{
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struct in_addr src_addr; /* Address and port information */
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struct in_addr dst_addr; /* . */
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struct in_addr alias_addr; /* . */
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u_short src_port; /* . */
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u_short dst_port; /* . */
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u_short alias_port; /* . */
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int link_type; /* Type of link: tcp, udp, icmp, frag */
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/* values for link_type */
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#define LINK_ICMP 1
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#define LINK_UDP 2
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#define LINK_TCP 3
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#define LINK_FRAGMENT_ID 4
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#define LINK_FRAGMENT_PTR 5
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#define LINK_ADDR 6
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int flags; /* indicates special characteristics */
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/* flag bits */
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#define LINK_UNKNOWN_DEST_PORT 0x01
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#define LINK_UNKNOWN_DEST_ADDR 0x02
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#define LINK_PERMANENT 0x04
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#define LINK_PARTIALLY_SPECIFIED 0x03 /* logical-or of first two bits */
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int timestamp; /* Time link was last accessed */
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int expire_time; /* Expire time for link */
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int sockfd; /* socket descriptor */
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u_int start_point_out; /* Index number in output lookup table */
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u_int start_point_in;
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struct alias_link *next_out; /* Linked list pointers for input and */
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struct alias_link *last_out; /* output tables */
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struct alias_link *next_in; /* . */
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struct alias_link *last_in; /* . */
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union /* Auxiliary data */
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{
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char *frag_ptr;
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struct in_addr frag_addr;
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struct tcp_dat *tcp;
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} data;
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};
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/* Global Variables
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The global variables listed here are only accessed from
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within alias_db.c and so are prefixed with the static
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designation.
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*/
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int packetAliasMode; /* Mode flags */
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/* - documented in alias.h */
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static struct in_addr aliasAddress; /* Address written onto source */
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/* field of IP packet. */
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static struct in_addr targetAddress; /* IP address incoming packets */
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/* are sent to if no aliasing */
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/* link already exists */
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static struct in_addr nullAddress; /* Used as a dummy parameter for */
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/* some function calls */
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static struct alias_link *
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linkTableOut[LINK_TABLE_OUT_SIZE]; /* Lookup table of pointers to */
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/* chains of link records. Each */
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static struct alias_link * /* link record is doubly indexed */
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linkTableIn[LINK_TABLE_IN_SIZE]; /* into input and output lookup */
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/* tables. */
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static int icmpLinkCount; /* Link statistics */
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static int udpLinkCount;
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static int tcpLinkCount;
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static int fragmentIdLinkCount;
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static int fragmentPtrLinkCount;
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static int sockCount;
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static int cleanupIndex; /* Index to chain of link table */
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/* being inspected for old links */
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static int timeStamp; /* System time in seconds for */
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/* current packet */
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static int lastCleanupTime; /* Last time IncrementalCleanup() */
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/* was called */
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static int houseKeepingResidual; /* used by HouseKeeping() */
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static int deleteAllLinks; /* If equal to zero, DeleteLink() */
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/* will not remove permanent links */
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static FILE *monitorFile; /* File descriptor for link */
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/* statistics monitoring file */
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static int firstCall = 1; /* Needed by InitAlias() */
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static int newDefaultLink; /* Indicates if a new aliasing */
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/* link has been created after a */
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/* call to PacketAliasIn/Out(). */
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/* Internal utility routines (used only in alias_db.c)
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Lookup table starting points:
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StartPointIn() -- link table initial search point for
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outgoing packets
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StartPointOut() -- port table initial search point for
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incoming packets
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Miscellaneous:
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SeqDiff() -- difference between two TCP sequences
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ShowAliasStats() -- send alias statistics to a monitor file
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*/
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/* Local prototypes */
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static u_int StartPointIn(struct in_addr, u_short, int);
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static u_int StartPointOut(struct in_addr, struct in_addr,
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u_short, u_short, int);
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static int SeqDiff(u_long, u_long);
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static void ShowAliasStats(void);
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static u_int
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StartPointIn(struct in_addr alias_addr,
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u_short alias_port,
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int link_type)
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{
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u_int n;
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n = alias_addr.s_addr;
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n += alias_port;
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n += link_type;
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return(n % LINK_TABLE_IN_SIZE);
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}
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static u_int
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StartPointOut(struct in_addr src_addr, struct in_addr dst_addr,
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u_short src_port, u_short dst_port, int link_type)
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{
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u_int n;
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n = src_addr.s_addr;
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n += dst_addr.s_addr;
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n += src_port;
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n += dst_port;
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n += link_type;
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return(n % LINK_TABLE_OUT_SIZE);
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}
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static int
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SeqDiff(u_long x, u_long y)
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{
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/* Return the difference between two TCP sequence numbers */
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/*
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This function is encapsulated in case there are any unusual
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arithmetic conditions that need to be considered.
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*/
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return (ntohl(y) - ntohl(x));
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}
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static void
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ShowAliasStats(void)
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{
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/* Used for debugging */
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if (packetAliasMode & PKT_ALIAS_LOG)
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{
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fprintf(monitorFile, "icmp=%d, udp=%d, tcp=%d, frag_id=%d frag_ptr=%d",
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icmpLinkCount,
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udpLinkCount,
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tcpLinkCount,
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fragmentIdLinkCount,
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fragmentPtrLinkCount);
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fprintf(monitorFile, " / tot=%d (sock=%d)\n",
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icmpLinkCount + udpLinkCount
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+ tcpLinkCount
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+ fragmentIdLinkCount
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+ fragmentPtrLinkCount,
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sockCount);
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fflush(monitorFile);
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}
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}
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/* Internal routines for finding, deleting and adding links
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Port Allocation:
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GetNewPort() -- find and reserve new alias port number
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GetSocket() -- try to allocate a socket for a given port
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Link creation and deletion:
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CleanupAliasData() - remove all link chains from lookup table
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IncrementalCleanup() - look for stale links in a single chain
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DeleteLink() - remove link
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AddLink() - add link
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Link search:
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FindLinkOut() - find link for outgoing packets
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FindLinkIn() - find link for incoming packets
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*/
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/* Local prototypes */
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static int GetNewPort(struct alias_link *, int);
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static u_short GetSocket(u_short, int *, int);
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static void CleanupAliasData(void);
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static void IncrementalCleanup(void);
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static void DeleteLink(struct alias_link *);
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static struct alias_link *
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AddLink(struct in_addr, struct in_addr, struct in_addr,
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u_short, u_short, int, int);
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static struct alias_link *
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FindLinkOut(struct in_addr, struct in_addr, u_short, u_short, int);
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static struct alias_link *
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FindLinkIn(struct in_addr, struct in_addr, u_short, u_short, int, int);
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#define ALIAS_PORT_BASE 0x08000
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#define ALIAS_PORT_MASK 0x07fff
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#define GET_NEW_PORT_MAX_ATTEMPTS 20
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#define GET_ALIAS_PORT -1
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#define GET_ALIAS_ID GET_ALIAS_PORT
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/* GetNewPort() allocates port numbers. Note that if a port number
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is already in use, that does not mean that it cannot be used by
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another link concurrently. This is because GetNewPort() looks for
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unused triplets: (dest addr, dest port, alias port). */
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static int
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GetNewPort(struct alias_link *link, int alias_port_param)
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{
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int i;
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int max_trials;
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u_short port_sys;
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u_short port_net;
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/*
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Description of alias_port_param for GetNewPort(). When
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this parameter is zero or positive, it precisely specifies
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the port number. GetNewPort() will return this number
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without check that it is in use.
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Whis this parameter is -1, it indicates to get a randomly
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selected port number.
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*/
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if (alias_port_param == GET_ALIAS_PORT)
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{
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/*
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* The aliasing port is automatically selected
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* by one of two methods below:
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*/
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max_trials = GET_NEW_PORT_MAX_ATTEMPTS;
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if (packetAliasMode & PKT_ALIAS_SAME_PORTS)
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{
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/*
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* When the ALIAS_SAME_PORTS option is
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* chosen, the first try will be the
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* actual source port. If this is already
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* in use, the remainder of the trials
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* will be random.
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*/
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port_net = link->src_port;
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port_sys = ntohs(port_net);
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}
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else
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{
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/* First trial and all subsequent are random. */
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port_sys = random() & ALIAS_PORT_MASK;
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port_sys += ALIAS_PORT_BASE;
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port_net = htons(port_sys);
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}
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}
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else if (alias_port_param >= 0 && alias_port_param < 0x10000)
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{
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link->alias_port = (u_short) alias_port_param;
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return(0);
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}
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else
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{
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fprintf(stderr, "PacketAlias/GetNewPort(): ");
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fprintf(stderr, "input parameter error\n");
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return(-1);
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}
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/* Port number search */
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for (i=0; i<max_trials; i++)
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{
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int go_ahead;
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struct alias_link *search_result;
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search_result = FindLinkIn(link->dst_addr, link->alias_addr,
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link->dst_port, port_net,
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link->link_type, 0);
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if (search_result == NULL)
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go_ahead = 1;
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else if (!(link->flags & LINK_PARTIALLY_SPECIFIED)
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&& (search_result->flags & LINK_PARTIALLY_SPECIFIED))
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go_ahead = 1;
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else
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go_ahead = 0;
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if (go_ahead)
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{
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if ((packetAliasMode && PKT_ALIAS_USE_SOCKETS)
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&& (link->flags & LINK_PARTIALLY_SPECIFIED))
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{
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if (GetSocket(port_net, &link->sockfd, link->link_type))
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{
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link->alias_port = port_net;
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return(0);
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}
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}
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else
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{
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link->alias_port = port_net;
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return(0);
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}
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}
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|
|
port_sys = random() & ALIAS_PORT_MASK;
|
|
port_sys += ALIAS_PORT_BASE;
|
|
port_net = htons(port_sys);
|
|
}
|
|
|
|
fprintf(stderr, "PacketAlias/GetnewPort(): ");
|
|
fprintf(stderr, "could not find free port\n");
|
|
|
|
return(-1);
|
|
}
|
|
|
|
|
|
static u_short
|
|
GetSocket(u_short port_net, int *sockfd, int link_type)
|
|
{
|
|
int err;
|
|
int sock;
|
|
struct sockaddr_in sock_addr;
|
|
|
|
if (link_type == LINK_TCP)
|
|
sock = socket(AF_INET, SOCK_STREAM, 0);
|
|
else if (link_type == LINK_UDP)
|
|
sock = socket(AF_INET, SOCK_DGRAM, 0);
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAlias/GetSocket(): ");
|
|
fprintf(stderr, "incorrect link type\n");
|
|
return(0);
|
|
}
|
|
|
|
if (sock < 0)
|
|
{
|
|
fprintf(stderr, "PacketAlias/GetSocket(): ");
|
|
fprintf(stderr, "socket() error %d\n", *sockfd);
|
|
return(0);
|
|
}
|
|
|
|
sock_addr.sin_family = AF_INET;
|
|
sock_addr.sin_addr.s_addr = htonl(INADDR_ANY);
|
|
sock_addr.sin_port = port_net;
|
|
|
|
err = bind(sock,
|
|
(struct sockaddr *) &sock_addr,
|
|
sizeof(sock_addr));
|
|
if (err == 0)
|
|
{
|
|
sockCount++;
|
|
*sockfd = sock;
|
|
return(1);
|
|
}
|
|
else
|
|
{
|
|
close(sock);
|
|
return(0);
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
CleanupAliasData(void)
|
|
{
|
|
struct alias_link *link;
|
|
int i, icount;
|
|
|
|
icount = 0;
|
|
for (i=0; i<LINK_TABLE_OUT_SIZE; i++)
|
|
{
|
|
link = linkTableOut[i];
|
|
linkTableOut[i] = NULL;
|
|
while (link != NULL)
|
|
{
|
|
struct alias_link *link_next;
|
|
link_next = link->next_out;
|
|
icount++;
|
|
DeleteLink(link);
|
|
link = link_next;
|
|
}
|
|
}
|
|
|
|
cleanupIndex =0;
|
|
}
|
|
|
|
|
|
static void
|
|
IncrementalCleanup(void)
|
|
{
|
|
int icount;
|
|
struct alias_link *link;
|
|
|
|
icount = 0;
|
|
link = linkTableOut[cleanupIndex++];
|
|
while (link != NULL)
|
|
{
|
|
int idelta;
|
|
struct alias_link *link_next;
|
|
|
|
link_next = link->next_out;
|
|
idelta = timeStamp - link->timestamp;
|
|
switch (link->link_type)
|
|
{
|
|
case LINK_ICMP:
|
|
case LINK_UDP:
|
|
case LINK_FRAGMENT_ID:
|
|
case LINK_FRAGMENT_PTR:
|
|
if (idelta > link->expire_time)
|
|
{
|
|
DeleteLink(link);
|
|
icount++;
|
|
}
|
|
break;
|
|
case LINK_TCP:
|
|
if (idelta > link->expire_time)
|
|
{
|
|
struct tcp_dat *tcp_aux;
|
|
|
|
tcp_aux = link->data.tcp;
|
|
if (tcp_aux->state.in != 1
|
|
|| tcp_aux->state.out != 1)
|
|
{
|
|
DeleteLink(link);
|
|
icount++;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
link = link_next;
|
|
}
|
|
|
|
if (cleanupIndex == LINK_TABLE_OUT_SIZE)
|
|
cleanupIndex = 0;
|
|
}
|
|
|
|
void
|
|
DeleteLink(struct alias_link *link)
|
|
{
|
|
struct alias_link *link_last;
|
|
struct alias_link *link_next;
|
|
|
|
/* Don't do anything if the link is marked permanent */
|
|
if (deleteAllLinks == 0 && link->flags & LINK_PERMANENT)
|
|
return;
|
|
|
|
/* Adjust output table pointers */
|
|
link_last = link->last_out;
|
|
link_next = link->next_out;
|
|
|
|
if (link_last != NULL)
|
|
link_last->next_out = link_next;
|
|
else
|
|
linkTableOut[link->start_point_out] = link_next;
|
|
|
|
if (link_next != NULL)
|
|
link_next->last_out = link_last;
|
|
|
|
/* Adjust input table pointers */
|
|
link_last = link->last_in;
|
|
link_next = link->next_in;
|
|
|
|
if (link_last != NULL)
|
|
link_last->next_in = link_next;
|
|
else
|
|
linkTableIn[link->start_point_in] = link_next;
|
|
|
|
if (link_next != NULL)
|
|
link_next->last_in = link_last;
|
|
|
|
/* Close socket, if one has been allocated */
|
|
if (link->sockfd != -1)
|
|
{
|
|
sockCount--;
|
|
close(link->sockfd);
|
|
}
|
|
|
|
/* Link-type dependent cleanup */
|
|
switch(link->link_type)
|
|
{
|
|
case LINK_ICMP:
|
|
icmpLinkCount--;
|
|
break;
|
|
case LINK_UDP:
|
|
udpLinkCount--;
|
|
break;
|
|
case LINK_TCP:
|
|
tcpLinkCount--;
|
|
if (link->data.tcp != NULL)
|
|
free(link->data.tcp);
|
|
break;
|
|
case LINK_FRAGMENT_ID:
|
|
fragmentIdLinkCount--;
|
|
break;
|
|
case LINK_FRAGMENT_PTR:
|
|
fragmentPtrLinkCount--;
|
|
if (link->data.frag_ptr != NULL)
|
|
free(link->data.frag_ptr);
|
|
break;
|
|
}
|
|
|
|
/* Free memory */
|
|
free(link);
|
|
|
|
/* Write statistics, if logging enabled */
|
|
if (packetAliasMode & PKT_ALIAS_LOG)
|
|
{
|
|
ShowAliasStats();
|
|
}
|
|
}
|
|
|
|
|
|
static struct alias_link *
|
|
AddLink(struct in_addr src_addr,
|
|
struct in_addr dst_addr,
|
|
struct in_addr alias_addr,
|
|
u_short src_port,
|
|
u_short dst_port,
|
|
int alias_port_param, /* if less than zero, alias */
|
|
int link_type) /* port will be automatically */
|
|
{ /* chosen. If greater than */
|
|
u_int start_point; /* zero, equal to alias port */
|
|
struct alias_link *link;
|
|
struct alias_link *first_link;
|
|
|
|
link = malloc(sizeof(struct alias_link));
|
|
if (link != NULL)
|
|
{
|
|
/* If either the aliasing address or source address are
|
|
equal to the default device address (equal to the
|
|
global variable aliasAddress), then set the alias
|
|
address field of the link record to zero */
|
|
|
|
if (src_addr.s_addr == aliasAddress.s_addr)
|
|
src_addr.s_addr = 0;
|
|
|
|
if (alias_addr.s_addr == aliasAddress.s_addr)
|
|
alias_addr.s_addr = 0;
|
|
|
|
/* Basic initialization */
|
|
link->src_addr = src_addr;
|
|
link->dst_addr = dst_addr;
|
|
link->src_port = src_port;
|
|
link->alias_addr = alias_addr;
|
|
link->dst_port = dst_port;
|
|
link->link_type = link_type;
|
|
link->sockfd = -1;
|
|
link->flags = 0;
|
|
link->timestamp = timeStamp;
|
|
|
|
/* Expiration time */
|
|
switch (link_type)
|
|
{
|
|
case LINK_ICMP:
|
|
link->expire_time = ICMP_EXPIRE_TIME;
|
|
break;
|
|
case LINK_UDP:
|
|
link->expire_time = UDP_EXPIRE_TIME;
|
|
break;
|
|
case LINK_TCP:
|
|
link->expire_time = TCP_EXPIRE_TIME;
|
|
break;
|
|
case LINK_FRAGMENT_ID:
|
|
link->expire_time = FRAGMENT_ID_EXPIRE_TIME;
|
|
break;
|
|
case LINK_FRAGMENT_PTR:
|
|
link->expire_time = FRAGMENT_PTR_EXPIRE_TIME;
|
|
break;
|
|
}
|
|
|
|
/* Determine alias flags */
|
|
if (dst_addr.s_addr == 0)
|
|
link->flags |= LINK_UNKNOWN_DEST_ADDR;
|
|
if (dst_port == 0)
|
|
link->flags |= LINK_UNKNOWN_DEST_PORT;
|
|
|
|
/* Determine alias port */
|
|
if (GetNewPort(link, alias_port_param) != 0)
|
|
{
|
|
free(link);
|
|
return(NULL);
|
|
}
|
|
|
|
/* Set up pointers for output lookup table */
|
|
start_point = StartPointOut(src_addr, dst_addr,
|
|
src_port, dst_port, link_type);
|
|
first_link = linkTableOut[start_point];
|
|
|
|
link->last_out = NULL;
|
|
link->next_out = first_link;
|
|
link->start_point_out = start_point;
|
|
|
|
if (first_link != NULL)
|
|
first_link->last_out = link;
|
|
|
|
linkTableOut[start_point] = link;
|
|
|
|
/* Set up pointers for input lookup table */
|
|
start_point = StartPointIn(alias_addr, link->alias_port, link_type);
|
|
first_link = linkTableIn[start_point];
|
|
|
|
link->last_in = NULL;
|
|
link->next_in = first_link;
|
|
link->start_point_in = start_point;
|
|
|
|
if (first_link != NULL)
|
|
first_link->last_in = link;
|
|
|
|
linkTableIn[start_point] = link;
|
|
|
|
/* Link-type dependent initialization */
|
|
switch(link_type)
|
|
{
|
|
struct tcp_dat *aux_tcp;
|
|
|
|
case LINK_ICMP:
|
|
icmpLinkCount++;
|
|
break;
|
|
case LINK_UDP:
|
|
udpLinkCount++;
|
|
break;
|
|
case LINK_TCP:
|
|
aux_tcp = malloc(sizeof(struct tcp_dat));
|
|
link->data.tcp = aux_tcp;
|
|
if (aux_tcp != NULL)
|
|
{
|
|
int i;
|
|
|
|
tcpLinkCount++;
|
|
aux_tcp->state.in = 0;
|
|
aux_tcp->state.out = 0;
|
|
aux_tcp->state.index = 0;
|
|
aux_tcp->state.ack_modified = 0;
|
|
for (i=0; i<N_LINK_TCP_DATA; i++)
|
|
aux_tcp->ack[i].active = 0;
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAlias/AddLink: ");
|
|
fprintf(stderr, " cannot allocate auxiliary TCP data\n");
|
|
}
|
|
break;
|
|
case LINK_FRAGMENT_ID:
|
|
fragmentIdLinkCount++;
|
|
break;
|
|
case LINK_FRAGMENT_PTR:
|
|
fragmentPtrLinkCount++;
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAlias/AddLink(): ");
|
|
fprintf(stderr, "malloc() call failed.\n");
|
|
}
|
|
|
|
if (packetAliasMode & PKT_ALIAS_LOG)
|
|
{
|
|
ShowAliasStats();
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
static struct alias_link *
|
|
FindLinkOut(struct in_addr src_addr,
|
|
struct in_addr dst_addr,
|
|
u_short src_port,
|
|
u_short dst_port,
|
|
int link_type)
|
|
{
|
|
u_int i;
|
|
struct alias_link *link;
|
|
|
|
if (src_addr.s_addr == aliasAddress.s_addr)
|
|
src_addr.s_addr = 0;
|
|
|
|
i = StartPointOut(src_addr, dst_addr, src_port, dst_port, link_type);
|
|
link = linkTableOut[i];
|
|
while (link != NULL)
|
|
{
|
|
if (link->src_addr.s_addr == src_addr.s_addr
|
|
&& link->dst_addr.s_addr == dst_addr.s_addr
|
|
&& link->dst_port == dst_port
|
|
&& link->src_port == src_port
|
|
&& link->link_type == link_type)
|
|
{
|
|
link->timestamp = timeStamp;
|
|
break;
|
|
}
|
|
link = link->next_out;
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindLinkIn(struct in_addr dst_addr,
|
|
struct in_addr alias_addr,
|
|
u_short dst_port,
|
|
u_short alias_port,
|
|
int link_type,
|
|
int replace_partial_links)
|
|
{
|
|
int flags_in;
|
|
u_int start_point;
|
|
struct alias_link *link;
|
|
struct alias_link *link_fully_specified;
|
|
struct alias_link *link_unknown_all;
|
|
struct alias_link *link_unknown_dst_addr;
|
|
struct alias_link *link_unknown_dst_port;
|
|
|
|
/* Initialize pointers */
|
|
link_fully_specified = NULL;
|
|
link_unknown_all = NULL;
|
|
link_unknown_dst_addr = NULL;
|
|
link_unknown_dst_port = NULL;
|
|
|
|
/* If either the dest addr or port is unknown, the search
|
|
loop will have to know about this. */
|
|
|
|
flags_in = 0;
|
|
if (dst_addr.s_addr == 0)
|
|
flags_in |= LINK_UNKNOWN_DEST_ADDR;
|
|
if (dst_port == 0)
|
|
flags_in |= LINK_UNKNOWN_DEST_PORT;
|
|
|
|
/* The following allows permanent links to be
|
|
be specified as using the default aliasing address
|
|
(i.e. device interface address) without knowing
|
|
in advance what that address is. */
|
|
|
|
if (alias_addr.s_addr == aliasAddress.s_addr)
|
|
alias_addr.s_addr = 0;
|
|
|
|
/* Search loop */
|
|
start_point = StartPointIn(alias_addr, alias_port, link_type);
|
|
link = linkTableIn[start_point];
|
|
while (link != NULL)
|
|
{
|
|
int flags;
|
|
|
|
flags = flags_in | link->flags;
|
|
if (!(flags & LINK_PARTIALLY_SPECIFIED))
|
|
{
|
|
if (link->alias_addr.s_addr == alias_addr.s_addr
|
|
&& link->alias_port == alias_port
|
|
&& link->dst_addr.s_addr == dst_addr.s_addr
|
|
&& link->dst_port == dst_port
|
|
&& link->link_type == link_type)
|
|
{
|
|
link_fully_specified = link;
|
|
break;
|
|
}
|
|
}
|
|
else if ((flags & LINK_UNKNOWN_DEST_ADDR)
|
|
&& (flags & LINK_UNKNOWN_DEST_PORT))
|
|
{
|
|
if (link->alias_addr.s_addr == alias_addr.s_addr
|
|
&& link->alias_port == alias_port
|
|
&& link->link_type == link_type)
|
|
{
|
|
if (link_unknown_all == NULL)
|
|
link_unknown_all = link;
|
|
}
|
|
}
|
|
else if (flags & LINK_UNKNOWN_DEST_ADDR)
|
|
{
|
|
if (link->alias_addr.s_addr == alias_addr.s_addr
|
|
&& link->alias_port == alias_port
|
|
&& link->link_type == link_type
|
|
&& link->dst_port == dst_port)
|
|
{
|
|
if (link_unknown_dst_addr == NULL)
|
|
link_unknown_dst_addr = link;
|
|
}
|
|
}
|
|
else if (flags & LINK_UNKNOWN_DEST_PORT)
|
|
{
|
|
if (link->alias_addr.s_addr == alias_addr.s_addr
|
|
&& link->alias_port == alias_port
|
|
&& link->link_type == link_type
|
|
&& link->dst_addr.s_addr == dst_addr.s_addr)
|
|
{
|
|
if (link_unknown_dst_port == NULL)
|
|
link_unknown_dst_port = link;
|
|
}
|
|
}
|
|
link = link->next_in;
|
|
}
|
|
|
|
|
|
|
|
if (link_fully_specified != NULL)
|
|
{
|
|
return (link_fully_specified);
|
|
}
|
|
else if (link_unknown_dst_port != NULL)
|
|
{
|
|
if (replace_partial_links)
|
|
{
|
|
link = AddLink(link_unknown_dst_port->src_addr, dst_addr,
|
|
alias_addr,
|
|
link_unknown_dst_port->src_port, dst_port,
|
|
alias_port, link_type);
|
|
DeleteLink(link_unknown_dst_port);
|
|
return(link);
|
|
}
|
|
else
|
|
{
|
|
return(link_unknown_dst_port);
|
|
}
|
|
}
|
|
else if (link_unknown_dst_addr != NULL)
|
|
{
|
|
if (replace_partial_links)
|
|
{
|
|
link = AddLink(link_unknown_dst_addr->src_addr, dst_addr,
|
|
alias_addr,
|
|
link_unknown_dst_addr->src_port, dst_port,
|
|
alias_port, link_type);
|
|
DeleteLink(link_unknown_dst_addr);
|
|
return(link);
|
|
}
|
|
else
|
|
{
|
|
return(link_unknown_dst_addr);
|
|
}
|
|
}
|
|
else if (link_unknown_all != NULL)
|
|
{
|
|
if (replace_partial_links)
|
|
{
|
|
link = AddLink(link_unknown_all->src_addr, dst_addr,
|
|
alias_addr,
|
|
link_unknown_all->src_port, dst_port,
|
|
alias_port, link_type);
|
|
DeleteLink(link_unknown_all);
|
|
return(link);
|
|
}
|
|
else
|
|
{
|
|
return(link_unknown_all);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
return(NULL);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
|
|
/* External routines for finding/adding links
|
|
|
|
-- "external" means outside alias_db.c, but within alias*.c --
|
|
|
|
FindIcmpIn(), FindIcmpOut()
|
|
FindFragmentIn1(), FindFragmentIn2()
|
|
AddFragmentPtrLink(), FindFragmentPtr()
|
|
FindUdpTcpIn(), FindUdpTcpOut()
|
|
FindOriginalAddress(), FindAliasAddress()
|
|
|
|
(prototypes in alias_local.h)
|
|
*/
|
|
|
|
|
|
struct alias_link *
|
|
FindIcmpIn(struct in_addr dst_addr,
|
|
struct in_addr alias_addr,
|
|
u_short id_alias)
|
|
{
|
|
return FindLinkIn(dst_addr, alias_addr,
|
|
NO_DEST_PORT, id_alias,
|
|
LINK_ICMP, 0);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindIcmpOut(struct in_addr src_addr,
|
|
struct in_addr dst_addr,
|
|
u_short id)
|
|
{
|
|
struct alias_link * link;
|
|
|
|
link = FindLinkOut(src_addr, dst_addr,
|
|
id, NO_DEST_PORT,
|
|
LINK_ICMP);
|
|
if (link == NULL)
|
|
{
|
|
struct in_addr alias_addr;
|
|
|
|
alias_addr = FindAliasAddress(src_addr);
|
|
link = AddLink(src_addr, dst_addr, alias_addr,
|
|
id, NO_DEST_PORT, GET_ALIAS_ID,
|
|
LINK_ICMP);
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindFragmentIn1(struct in_addr dst_addr,
|
|
struct in_addr alias_addr,
|
|
u_short ip_id)
|
|
{
|
|
struct alias_link *link;
|
|
|
|
link = FindLinkIn(dst_addr, alias_addr,
|
|
NO_DEST_PORT, ip_id,
|
|
LINK_FRAGMENT_ID, 0);
|
|
|
|
if (link == NULL)
|
|
{
|
|
link = AddLink(nullAddress, dst_addr, alias_addr,
|
|
NO_SRC_PORT, NO_DEST_PORT, ip_id,
|
|
LINK_FRAGMENT_ID);
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindFragmentIn2(struct in_addr dst_addr, /* Doesn't add a link if one */
|
|
struct in_addr alias_addr, /* is not found. */
|
|
u_short ip_id)
|
|
{
|
|
return FindLinkIn(dst_addr, alias_addr,
|
|
NO_DEST_PORT, ip_id,
|
|
LINK_FRAGMENT_ID, 0);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
AddFragmentPtrLink(struct in_addr dst_addr,
|
|
u_short ip_id)
|
|
{
|
|
return AddLink(nullAddress, dst_addr, nullAddress,
|
|
NO_SRC_PORT, NO_DEST_PORT, ip_id,
|
|
LINK_FRAGMENT_PTR);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindFragmentPtr(struct in_addr dst_addr,
|
|
u_short ip_id)
|
|
{
|
|
return FindLinkIn(dst_addr, nullAddress,
|
|
NO_DEST_PORT, ip_id,
|
|
LINK_FRAGMENT_PTR, 0);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindUdpTcpIn(struct in_addr dst_addr,
|
|
struct in_addr alias_addr,
|
|
u_short dst_port,
|
|
u_short alias_port,
|
|
u_char proto)
|
|
{
|
|
int link_type;
|
|
struct alias_link *link;
|
|
|
|
switch (proto)
|
|
{
|
|
case IPPROTO_UDP:
|
|
link_type = LINK_UDP;
|
|
break;
|
|
case IPPROTO_TCP:
|
|
link_type = LINK_TCP;
|
|
break;
|
|
default:
|
|
return NULL;
|
|
break;
|
|
}
|
|
|
|
link = FindLinkIn(dst_addr, alias_addr,
|
|
dst_port, alias_port,
|
|
link_type, 1);
|
|
|
|
if ( !(packetAliasMode & PKT_ALIAS_DENY_INCOMING) && link == NULL)
|
|
{
|
|
struct in_addr target_addr;
|
|
|
|
target_addr = FindOriginalAddress(alias_addr);
|
|
link = AddLink(target_addr, dst_addr, alias_addr,
|
|
alias_port, dst_port, alias_port,
|
|
link_type);
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
struct alias_link *
|
|
FindUdpTcpOut(struct in_addr src_addr,
|
|
struct in_addr dst_addr,
|
|
u_short src_port,
|
|
u_short dst_port,
|
|
u_char proto)
|
|
{
|
|
int link_type;
|
|
struct alias_link *link;
|
|
|
|
switch (proto)
|
|
{
|
|
case IPPROTO_UDP:
|
|
link_type = LINK_UDP;
|
|
break;
|
|
case IPPROTO_TCP:
|
|
link_type = LINK_TCP;
|
|
break;
|
|
default:
|
|
return NULL;
|
|
break;
|
|
}
|
|
|
|
link = FindLinkOut(src_addr, dst_addr, src_port, dst_port, link_type);
|
|
|
|
if (link == NULL)
|
|
{
|
|
struct in_addr alias_addr;
|
|
|
|
alias_addr = FindAliasAddress(src_addr);
|
|
link = AddLink(src_addr, dst_addr, alias_addr,
|
|
src_port, dst_port, GET_ALIAS_PORT,
|
|
link_type);
|
|
}
|
|
|
|
return(link);
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
FindOriginalAddress(struct in_addr alias_addr)
|
|
{
|
|
struct alias_link *link;
|
|
|
|
link = FindLinkIn(nullAddress, alias_addr,
|
|
0, 0, LINK_ADDR, 0);
|
|
if (link == NULL)
|
|
{
|
|
newDefaultLink = 1;
|
|
if (targetAddress.s_addr != 0)
|
|
return targetAddress;
|
|
else
|
|
return alias_addr;
|
|
}
|
|
else
|
|
{
|
|
if (link->src_addr.s_addr == 0)
|
|
return aliasAddress;
|
|
else
|
|
return link->src_addr;
|
|
}
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
FindAliasAddress(struct in_addr original_addr)
|
|
{
|
|
struct alias_link *link;
|
|
|
|
link = FindLinkOut(original_addr, nullAddress,
|
|
0, 0, LINK_ADDR);
|
|
if (link == NULL)
|
|
{
|
|
return aliasAddress;
|
|
}
|
|
else
|
|
{
|
|
if (link->alias_addr.s_addr == 0)
|
|
return aliasAddress;
|
|
else
|
|
return link->alias_addr;
|
|
}
|
|
}
|
|
|
|
|
|
/* External routines for getting or changing link data
|
|
(external to alias_db.c, but internal to alias*.c)
|
|
|
|
SetFragmentData(), GetFragmentData()
|
|
SetFragmentPtr(), GetFragmentPtr()
|
|
SetStateIn(), SetStateOut(), GetStateIn(), GetStateOut()
|
|
GetOriginalAddress(), GetDestAddress(), GetAliasAddress()
|
|
GetOriginalPort(), GetAliasPort()
|
|
SetAckModified(), GetAckModified()
|
|
GetDeltaAckIn(), GetDeltaSeqOut(), AddSeq()
|
|
*/
|
|
|
|
|
|
void
|
|
SetFragmentAddr(struct alias_link *link, struct in_addr src_addr)
|
|
{
|
|
link->data.frag_addr = src_addr;
|
|
}
|
|
|
|
|
|
void
|
|
GetFragmentAddr(struct alias_link *link, struct in_addr *src_addr)
|
|
{
|
|
*src_addr = link->data.frag_addr;
|
|
}
|
|
|
|
|
|
void
|
|
SetFragmentPtr(struct alias_link *link, char *fptr)
|
|
{
|
|
link->data.frag_ptr = fptr;
|
|
}
|
|
|
|
|
|
void
|
|
GetFragmentPtr(struct alias_link *link, char **fptr)
|
|
{
|
|
*fptr = link->data.frag_ptr;
|
|
}
|
|
|
|
|
|
void
|
|
SetStateIn(struct alias_link *link, int state)
|
|
{
|
|
/* TCP input state */
|
|
(link->data.tcp)->state.in = state;
|
|
}
|
|
|
|
|
|
void
|
|
SetStateOut(struct alias_link *link, int state)
|
|
{
|
|
/* TCP output state */
|
|
(link->data.tcp)->state.out = state;
|
|
}
|
|
|
|
|
|
int
|
|
GetStateIn(struct alias_link *link)
|
|
{
|
|
/* TCP input state */
|
|
return( (link->data.tcp)->state.in);
|
|
}
|
|
|
|
|
|
int
|
|
GetStateOut(struct alias_link *link)
|
|
{
|
|
/* TCP output state */
|
|
return( (link->data.tcp)->state.out);
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
GetOriginalAddress(struct alias_link *link)
|
|
{
|
|
if (link->src_addr.s_addr == 0)
|
|
return aliasAddress;
|
|
else
|
|
return(link->src_addr);
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
GetDestAddress(struct alias_link *link)
|
|
{
|
|
return(link->dst_addr);
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
GetAliasAddress(struct alias_link *link)
|
|
{
|
|
if (link->alias_addr.s_addr == 0)
|
|
return aliasAddress;
|
|
else
|
|
return link->alias_addr;
|
|
}
|
|
|
|
|
|
struct in_addr
|
|
GetDefaultAliasAddress()
|
|
{
|
|
return aliasAddress;
|
|
}
|
|
|
|
|
|
void
|
|
SetDefaultAliasAddress(struct in_addr alias_addr)
|
|
{
|
|
aliasAddress = alias_addr;
|
|
}
|
|
|
|
|
|
u_short
|
|
GetOriginalPort(struct alias_link *link)
|
|
{
|
|
return(link->src_port);
|
|
}
|
|
|
|
|
|
u_short
|
|
GetAliasPort(struct alias_link *link)
|
|
{
|
|
return(link->alias_port);
|
|
}
|
|
|
|
|
|
void
|
|
SetAckModified(struct alias_link *link)
|
|
{
|
|
/* Indicate that ack numbers have been modified in a TCP connection */
|
|
(link->data.tcp)->state.ack_modified = 1;
|
|
}
|
|
|
|
|
|
int
|
|
GetAckModified(struct alias_link *link)
|
|
{
|
|
/* See if ack numbers have been modified */
|
|
return( (link->data.tcp)->state.ack_modified );
|
|
}
|
|
|
|
|
|
int
|
|
GetDeltaAckIn(struct ip *pip, struct alias_link *link)
|
|
{
|
|
/*
|
|
Find out how much the ack number has been altered for an incoming
|
|
TCP packet. To do this, a circular list is ack numbers where the TCP
|
|
packet size was altered is searched.
|
|
*/
|
|
|
|
int i;
|
|
struct tcphdr *tc;
|
|
int delta, ack_diff_min;
|
|
u_long ack;
|
|
|
|
tc = (struct tcphdr *) ((char *) pip + (pip->ip_hl << 2));
|
|
ack = tc->th_ack;
|
|
|
|
delta = 0;
|
|
ack_diff_min = -1;
|
|
for (i=0; i<N_LINK_TCP_DATA; i++)
|
|
{
|
|
struct ack_data_record x;
|
|
|
|
x = (link->data.tcp)->ack[i];
|
|
if (x.active == 1)
|
|
{
|
|
int ack_diff;
|
|
|
|
ack_diff = SeqDiff(x.ack_new, ack);
|
|
if (ack_diff >= 0)
|
|
{
|
|
if (ack_diff_min >= 0)
|
|
{
|
|
if (ack_diff < ack_diff_min)
|
|
{
|
|
delta = x.delta;
|
|
ack_diff_min = ack_diff;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
delta = x.delta;
|
|
ack_diff_min = ack_diff;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return (delta);
|
|
}
|
|
|
|
|
|
int
|
|
GetDeltaSeqOut(struct ip *pip, struct alias_link *link)
|
|
{
|
|
/*
|
|
Find out how much the seq number has been altered for an outgoing
|
|
TCP packet. To do this, a circular list is ack numbers where the TCP
|
|
packet size was altered is searched.
|
|
*/
|
|
|
|
int i;
|
|
struct tcphdr *tc;
|
|
int delta, seq_diff_min;
|
|
u_long seq;
|
|
|
|
tc = (struct tcphdr *) ((char *) pip + (pip->ip_hl << 2));
|
|
seq = tc->th_seq;
|
|
|
|
delta = 0;
|
|
seq_diff_min = -1;
|
|
for (i=0; i<N_LINK_TCP_DATA; i++)
|
|
{
|
|
struct ack_data_record x;
|
|
|
|
x = (link->data.tcp)->ack[i];
|
|
if (x.active == 1)
|
|
{
|
|
int seq_diff;
|
|
|
|
seq_diff = SeqDiff(x.ack_old, seq);
|
|
if (seq_diff >= 0)
|
|
{
|
|
if (seq_diff_min >= 0)
|
|
{
|
|
if (seq_diff < seq_diff_min)
|
|
{
|
|
delta = x.delta;
|
|
seq_diff_min = seq_diff;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
delta = x.delta;
|
|
seq_diff_min = seq_diff;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return (delta);
|
|
}
|
|
|
|
|
|
void
|
|
AddSeq(struct ip *pip, struct alias_link *link, int delta)
|
|
{
|
|
/*
|
|
When a TCP packet has been altered in length, save this
|
|
information in a circular list. If enough packets have
|
|
been altered, then this list will begin to overwrite itself.
|
|
*/
|
|
|
|
struct tcphdr *tc;
|
|
struct ack_data_record x;
|
|
int hlen, tlen, dlen;
|
|
int i;
|
|
|
|
tc = (struct tcphdr *) ((char *) pip + (pip->ip_hl << 2));
|
|
|
|
hlen = (pip->ip_hl + tc->th_off) << 2;
|
|
tlen = ntohs(pip->ip_len);
|
|
dlen = tlen - hlen;
|
|
|
|
x.ack_old = htonl(ntohl(tc->th_seq) + dlen);
|
|
x.ack_new = htonl(ntohl(tc->th_seq) + dlen + delta);
|
|
x.delta = delta;
|
|
x.active = 1;
|
|
|
|
i = (link->data.tcp)->state.index;
|
|
(link->data.tcp)->ack[i] = x;
|
|
|
|
i++;
|
|
if (i == N_LINK_TCP_DATA)
|
|
(link->data.tcp)->state.index = 0;
|
|
else
|
|
(link->data.tcp)->state.index = i;
|
|
}
|
|
|
|
void
|
|
SetExpire(struct alias_link *link, int expire)
|
|
{
|
|
if (expire == 0)
|
|
{
|
|
link->flags &= ~LINK_PERMANENT;
|
|
DeleteLink(link);
|
|
}
|
|
else if (expire == -1)
|
|
{
|
|
link->flags |= LINK_PERMANENT;
|
|
}
|
|
else if (expire > 0)
|
|
{
|
|
link->expire_time = expire;
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAlias/SetExpire(): ");
|
|
fprintf(stderr, "error in expire parameter\n");
|
|
}
|
|
}
|
|
|
|
void
|
|
ClearCheckNewLink(void)
|
|
{
|
|
newDefaultLink = 0;
|
|
}
|
|
|
|
|
|
/* Miscellaneous Functions
|
|
|
|
HouseKeeping()
|
|
InitPacketAliasLog()
|
|
UninitPacketAliasLog()
|
|
*/
|
|
|
|
/*
|
|
Whenever an outgoing or incoming packet is handled, HouseKeeping()
|
|
is called to find and remove timed-out aliasing links. Logic exists
|
|
to sweep through the entire table and linked list structure
|
|
every 60 seconds.
|
|
|
|
(prototype in alias_local.h)
|
|
*/
|
|
|
|
void
|
|
HouseKeeping(void)
|
|
{
|
|
int i, n, n100;
|
|
struct timeval tv;
|
|
struct timezone tz;
|
|
|
|
/*
|
|
* Save system time (seconds) in global variable timeStamp for
|
|
* use by other functions. This is done so as not to unnecessarily
|
|
* waste timeline by making system calls.
|
|
*/
|
|
gettimeofday(&tv, &tz);
|
|
timeStamp = tv.tv_sec;
|
|
|
|
/* Compute number of spokes (output table link chains) to cover */
|
|
n100 = LINK_TABLE_OUT_SIZE * 100 + houseKeepingResidual;
|
|
n100 *= timeStamp - lastCleanupTime;
|
|
n100 /= ALIAS_CLEANUP_INTERVAL_SECS;
|
|
|
|
n = n100/100;
|
|
|
|
/* Handle different cases */
|
|
if (n > ALIAS_CLEANUP_MAX_SPOKES)
|
|
{
|
|
n = ALIAS_CLEANUP_MAX_SPOKES;
|
|
lastCleanupTime = timeStamp;
|
|
houseKeepingResidual = 0;
|
|
|
|
for (i=0; i<n; i++)
|
|
IncrementalCleanup();
|
|
}
|
|
else if (n > 0)
|
|
{
|
|
lastCleanupTime = timeStamp;
|
|
houseKeepingResidual = n100 - 100*n;
|
|
|
|
for (i=0; i<n; i++)
|
|
IncrementalCleanup();
|
|
}
|
|
else if (n < 0)
|
|
{
|
|
fprintf(stderr, "PacketAlias/HouseKeeping(): ");
|
|
fprintf(stderr, "something unexpected in time values\n");
|
|
lastCleanupTime = timeStamp;
|
|
houseKeepingResidual = 0;
|
|
}
|
|
}
|
|
|
|
|
|
/* Init the log file and enable logging */
|
|
void
|
|
InitPacketAliasLog(void)
|
|
{
|
|
if ((~packetAliasMode & PKT_ALIAS_LOG)
|
|
&& (monitorFile = fopen("/var/log/alias.log", "w")))
|
|
{
|
|
packetAliasMode |= PKT_ALIAS_LOG;
|
|
fprintf(monitorFile,
|
|
"PacketAlias/InitPacketAliasLog: Packet alias logging enabled.\n");
|
|
}
|
|
}
|
|
|
|
|
|
/* Close the log-file and disable logging. */
|
|
void
|
|
UninitPacketAliasLog(void)
|
|
{
|
|
if( monitorFile )
|
|
fclose(monitorFile);
|
|
packetAliasMode &= ~PKT_ALIAS_LOG;
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/* Outside world interfaces
|
|
|
|
-- "outside world" means other than alias*.c routines --
|
|
|
|
PacketAliasRedirectPort()
|
|
PacketAliasRedirectAddr()
|
|
PacketAliasRedirectDelete()
|
|
PacketAliasSetAddress()
|
|
PacketAliasInit()
|
|
PacketAliasSetMode()
|
|
|
|
(prototypes in alias.h)
|
|
*/
|
|
|
|
/* Redirection from a specific public addr:port to a
|
|
a private addr:port */
|
|
struct alias_link *
|
|
PacketAliasRedirectPort(struct in_addr src_addr, u_short src_port,
|
|
struct in_addr dst_addr, u_short dst_port,
|
|
struct in_addr alias_addr, u_short alias_port,
|
|
u_char proto)
|
|
{
|
|
int link_type;
|
|
struct alias_link *link;
|
|
|
|
switch(proto)
|
|
{
|
|
case IPPROTO_UDP:
|
|
link_type = LINK_UDP;
|
|
break;
|
|
case IPPROTO_TCP:
|
|
link_type = LINK_TCP;
|
|
break;
|
|
default:
|
|
fprintf(stderr, "PacketAliasRedirectPort(): ");
|
|
fprintf(stderr, "only TCP and UDP protocols allowed\n");
|
|
return NULL;
|
|
}
|
|
|
|
link = AddLink(src_addr, dst_addr, alias_addr,
|
|
src_port, dst_port, alias_port,
|
|
link_type);
|
|
|
|
if (link != NULL)
|
|
{
|
|
link->flags |= LINK_PERMANENT;
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAliasRedirectPort(): "
|
|
"call to AddLink() failed\n");
|
|
}
|
|
|
|
return link;
|
|
}
|
|
|
|
|
|
/* Static address translation */
|
|
struct alias_link *
|
|
PacketAliasRedirectAddr(struct in_addr src_addr,
|
|
struct in_addr alias_addr)
|
|
{
|
|
struct alias_link *link;
|
|
|
|
link = AddLink(src_addr, nullAddress, alias_addr,
|
|
0, 0, 0,
|
|
LINK_ADDR);
|
|
|
|
if (link != NULL)
|
|
{
|
|
link->flags |= LINK_PERMANENT;
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "PacketAliasRedirectAddr(): "
|
|
"call to AddLink() failed\n");
|
|
}
|
|
|
|
return link;
|
|
}
|
|
|
|
|
|
void
|
|
PacketAliasRedirectDelete(struct alias_link *link)
|
|
{
|
|
/* This is a dangerous function to put in the API,
|
|
because an invalid pointer can crash the program. */
|
|
|
|
deleteAllLinks = 1;
|
|
DeleteLink(link);
|
|
deleteAllLinks = 0;
|
|
}
|
|
|
|
|
|
void
|
|
PacketAliasSetAddress(struct in_addr addr)
|
|
{
|
|
if (packetAliasMode & PKT_ALIAS_RESET_ON_ADDR_CHANGE
|
|
&& aliasAddress.s_addr != addr.s_addr)
|
|
{
|
|
CleanupAliasData();
|
|
aliasAddress = addr;
|
|
}
|
|
}
|
|
|
|
|
|
void
|
|
PacketAliasSetTarget(struct in_addr target_addr)
|
|
{
|
|
targetAddress = target_addr;
|
|
}
|
|
|
|
|
|
void
|
|
PacketAliasInit(void)
|
|
{
|
|
int i;
|
|
struct timeval tv;
|
|
struct timezone tz;
|
|
|
|
if (firstCall == 1)
|
|
{
|
|
gettimeofday(&tv, &tz);
|
|
timeStamp = tv.tv_sec;
|
|
lastCleanupTime = tv.tv_sec;
|
|
houseKeepingResidual = 0;
|
|
|
|
for (i=0; i<LINK_TABLE_OUT_SIZE; i++)
|
|
linkTableOut[i] = NULL;
|
|
for (i=0; i<LINK_TABLE_IN_SIZE; i++)
|
|
linkTableIn[i] = NULL;
|
|
|
|
firstCall = 0;
|
|
}
|
|
else
|
|
{
|
|
deleteAllLinks = 1;
|
|
CleanupAliasData();
|
|
deleteAllLinks = 0;
|
|
}
|
|
|
|
aliasAddress.s_addr = 0;
|
|
targetAddress.s_addr = 0;
|
|
|
|
icmpLinkCount = 0;
|
|
udpLinkCount = 0;
|
|
tcpLinkCount = 0;
|
|
fragmentIdLinkCount = 0;
|
|
fragmentPtrLinkCount = 0;
|
|
sockCount = 0;
|
|
|
|
cleanupIndex =0;
|
|
|
|
packetAliasMode = PKT_ALIAS_SAME_PORTS
|
|
| PKT_ALIAS_USE_SOCKETS
|
|
| PKT_ALIAS_RESET_ON_ADDR_CHANGE;
|
|
}
|
|
|
|
|
|
/* Change mode for some operations */
|
|
unsigned int
|
|
PacketAliasSetMode
|
|
(
|
|
unsigned int flags, /* Which state to bring flags to */
|
|
unsigned int mask /* Mask of which flags to affect (use 0 to do a
|
|
probe for flag values) */
|
|
)
|
|
{
|
|
/* Enable logging? */
|
|
if (flags & mask & PKT_ALIAS_LOG)
|
|
{
|
|
InitPacketAliasLog(); /* Do the enable */
|
|
}
|
|
/* _Disable_ logging? */
|
|
if (~flags & mask & PKT_ALIAS_LOG) {
|
|
UninitPacketAliasLog();
|
|
}
|
|
|
|
/* Other flags can be set/cleared without special action */
|
|
packetAliasMode = (flags & mask) | (packetAliasMode & ~mask);
|
|
return packetAliasMode;
|
|
}
|
|
|
|
|
|
int
|
|
PacketAliasCheckNewLink(void)
|
|
{
|
|
return newDefaultLink;
|
|
}
|