freebsd-dev/sys/netinet/libalias/alias_util.c

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/*-
* Copyright (c) 2001 Charles Mott <cm@linktel.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
2001-09-30 21:03:33 +00:00
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
2000-04-05 07:45:39 +00:00
Alias_util.c contains general utilities used by other functions
in the packet aliasing module. At the moment, there are functions
for computing IP header and TCP packet checksums.
The checksum routines are based upon example code in a Unix networking
text written by Stevens (sorry, I can't remember the title -- but
at least this is a good author).
Initial Version: August, 1996 (cjm)
Version 1.7: January 9, 1997
2004-07-05 10:53:28 +00:00
Added differential checksum update function.
*/
#ifdef _KERNEL
#include <sys/param.h>
Summer of Code 2005: improve libalias - part 1 of 2 With the first part of my previous Summer of Code work, we get: -made libalias modular: -support for 'particular' protocols (like ftp/irc/etcetc) is no more hardcoded inside libalias, but it's available through external modules loadable at runtime -modules are available both in kernel (/boot/kernel/alias_*.ko) and user land (/lib/libalias_*) -protocols/applications modularized are: cuseeme, ftp, irc, nbt, pptp, skinny and smedia -added logging support for kernel side -cleanup After a buildworld, do a 'mergemaster -i' to install the file libalias.conf in /etc or manually copy it. During startup (and after every HUP signal) user land applications running the new libalias will try to read a file in /etc called libalias.conf: that file contains the list of modules to load. User land applications affected by this commit are ppp and natd: if libalias.conf is present in /etc you won't notice any difference. The only kernel land bit affected by this commit is ng_nat: if you are using ng_nat, and it doesn't correctly handle ftp/irc/etcetc sessions anymore, remember to kldload the correspondent module (i.e. kldload alias_ftp). General information and details about the inner working are available in the libalias man page under the section 'MODULAR ARCHITECTURE (AND ipfw(4) SUPPORT)'. NOTA BENE: this commit affects _ONLY_ libalias, ipfw in-kernel nat support will be part of the next libalias-related commit. Approved by: glebius Reviewed by: glebius, ru
2006-09-26 23:26:53 +00:00
#include <sys/proc.h>
#else
#include <sys/types.h>
#include <stdio.h>
#endif
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#ifdef _KERNEL
#include <netinet/libalias/alias.h>
#include <netinet/libalias/alias_local.h>
#else
#include "alias.h"
#include "alias_local.h"
#endif
/*
* Note: the checksum routines assume that the actual checksum word has
* been zeroed out. If the checksum word is filled with the proper value,
* then these routines will give a result of zero (useful for testing
* purposes);
*/
u_short
LibAliasInternetChecksum(struct libalias *la __unused, u_short * ptr,
int nbytes)
{
int sum, oddbyte;
LIBALIAS_LOCK(la);
sum = 0;
while (nbytes > 1) {
sum += *ptr++;
nbytes -= 2;
}
if (nbytes == 1) {
oddbyte = 0;
((u_char *) & oddbyte)[0] = *(u_char *) ptr;
((u_char *) & oddbyte)[1] = 0;
sum += oddbyte;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
LIBALIAS_UNLOCK(la);
return (~sum);
}
#ifndef _KERNEL
u_short
IpChecksum(struct ip *pip)
{
return (LibAliasInternetChecksum(NULL, (u_short *) pip,
(pip->ip_hl << 2)));
}
2002-07-01 11:19:40 +00:00
u_short
TcpChecksum(struct ip *pip)
{
u_short *ptr;
struct tcphdr *tc;
int nhdr, ntcp, nbytes;
int sum, oddbyte;
nhdr = pip->ip_hl << 2;
ntcp = ntohs(pip->ip_len) - nhdr;
tc = (struct tcphdr *)ip_next(pip);
ptr = (u_short *) tc;
2002-07-01 11:19:40 +00:00
/* Add up TCP header and data */
nbytes = ntcp;
sum = 0;
while (nbytes > 1) {
sum += *ptr++;
nbytes -= 2;
}
if (nbytes == 1) {
oddbyte = 0;
((u_char *) & oddbyte)[0] = *(u_char *) ptr;
((u_char *) & oddbyte)[1] = 0;
sum += oddbyte;
}
/* "Pseudo-header" data */
ptr = (void *)&pip->ip_dst;
sum += *ptr++;
sum += *ptr;
ptr = (void *)&pip->ip_src;
sum += *ptr++;
sum += *ptr;
sum += htons((u_short) ntcp);
sum += htons((u_short) pip->ip_p);
/* Roll over carry bits */
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
/* Return checksum */
return ((u_short) ~ sum);
}
#endif /* not _KERNEL */
void
DifferentialChecksum(u_short * cksum, void *newp, void *oldp, int n)
{
int i;
int accumulate;
u_short *new = newp;
u_short *old = oldp;
accumulate = *cksum;
for (i = 0; i < n; i++) {
accumulate -= *new++;
accumulate += *old++;
}
if (accumulate < 0) {
accumulate = -accumulate;
accumulate = (accumulate >> 16) + (accumulate & 0xffff);
accumulate += accumulate >> 16;
*cksum = (u_short) ~ accumulate;
} else {
accumulate = (accumulate >> 16) + (accumulate & 0xffff);
accumulate += accumulate >> 16;
*cksum = (u_short) accumulate;
}
}