399 lines
10 KiB
C
399 lines
10 KiB
C
/* $NetBSD: iso_chksum.c,v 1.12 1999/12/04 12:16:02 ragge Exp $ */
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/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)iso_chksum.c 8.1 (Berkeley) 6/10/93
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*/
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/***********************************************************
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Copyright IBM Corporation 1987
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted,
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provided that the above copyright notice appear in all copies and that
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both that copyright notice and this permission notice appear in
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supporting documentation, and that the name of IBM not be
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used in advertising or publicity pertaining to distribution of the
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software without specific, written prior permission.
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IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
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ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
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IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
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ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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SOFTWARE.
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******************************************************************/
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/*
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* ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
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*/
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/*
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* ISO CHECKSUM
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*
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* The checksum generation and check routines are here. The checksum is 2 bytes
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* such that the sum of all the bytes b(i) == 0 and the sum of i * b(i) == 0.
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* The whole thing is complicated by the fact that the data are in mbuf
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* chains. Furthermore, there is the possibility of wraparound in the running
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* sums after adding up 4102 octets. In order to avoid doing a mod operation
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* after EACH add, we have restricted this implementation to negotiating a
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* maximum of 4096-octets per TPDU (for the transport layer). The routine
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* iso_check_csum doesn't need to know where the checksum octets are. The
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* routine iso_gen_csum takes a pointer to an mbuf chain (logically a chunk
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* of data), an offset into the chunk at which the 2 octets are to be
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* stuffed, and the length of the chunk. The 2 octets have to be logically
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* adjacent, but may be physically located in separate mbufs.
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*/
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#include "opt_iso.h"
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#ifdef ISO
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <netiso/argo_debug.h>
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#include <netiso/iso.h>
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#include <netiso/iso_var.h>
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#endif /* ISO */
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/*
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* FUNCTION: iso_check_csum
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*
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* PURPOSE: To check the checksum of the packet in the mbuf chain (m).
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* The total length of the packet is (len).
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* Called from tp_input() and clnp_intr()
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*
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* RETURNS: TRUE (something non-zero) if there is a checksum error,
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* FALSE if there was NO checksum error.
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*
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* SIDE EFFECTS: none
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*
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* NOTES: It might be possible to gain something by optimizing
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* this routine (unrolling loops, etc). But it is such
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* a horrible thing to fiddle with anyway, it probably
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* isn't worth it.
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*/
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int
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iso_check_csum(m, len)
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struct mbuf *m;
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int len;
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{
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register u_char *p = mtod(m, u_char *);
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register u_long c0 = 0, c1 = 0;
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register int i = 0;
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int cum = 0;/* cumulative length */
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int l;
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l = len;
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len = min(m->m_len, len);
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i = 0;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("iso_check_csum: m %p, l x%x, m->m_len x%x\n",
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m, l, m->m_len);
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}
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#endif
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while (i < l) {
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cum += len;
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while (i < cum) {
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c0 = c0 + *(p++);
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c1 += c0;
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i++;
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}
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if (i < l) {
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m = m->m_next;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("iso_check_csum: new mbuf\n");
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if (l - i < m->m_len)
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printf(
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"bad mbuf chain in check csum l 0x%x i 0x%x m_data %p",
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l, i, m->m_data);
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}
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#endif
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ASSERT(m != NULL);
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len = min(m->m_len, l - i);
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p = mtod(m, u_char *);
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}
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}
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if (((int) c0 % 255) || ((int) c1 % 255)) {
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x",
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l, cum, len, i);
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}
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#endif
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return ((int) c0 % 255) << 8 | ((int) c1 % 255);
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}
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return 0;
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}
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/*
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* FUNCTION: iso_gen_csum
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*
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* PURPOSE: To generate the checksum of the packet in the mbuf chain (m).
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* The first of the 2 (logically) adjacent checksum bytes
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* (x and y) go at offset (n).
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* (n) is an offset relative to the beginning of the data,
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* not the beginning of the mbuf.
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* (l) is the length of the total mbuf chain's data.
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* Called from tp_emit(), tp_error_emit()
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* clnp_emit_er(), clnp_forward(), clnp_output().
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*
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* RETURNS: Rien
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*
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* SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
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*
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* NOTES: Ditto the note for iso_check_csum().
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*/
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void
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iso_gen_csum(m, n, l)
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struct mbuf *m;
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int n; /* offset of 2 checksum bytes */
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int l;
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{
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register u_char *p = mtod(m, u_char *);
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register int c0 = 0, c1 = 0;
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register int i = 0;
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int loc = n++, len = 0; /* n is position, loc is
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* offset */
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u_char *xloc = NULL;
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u_char *yloc = NULL;
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int cum = 0;/* cum == cumulative length */
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("enter gen csum m %p n 0x%x l 0x%x\n",
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m, n - 1, l);
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}
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#endif
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while (i < l) {
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len = min(m->m_len, NBPG);
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/* RAH: don't cksum more than l bytes */
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len = min(len, l - i);
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cum += len;
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p = mtod(m, u_char *);
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if (loc >= 0) {
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if (loc < len) {
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xloc = loc + mtod(m, u_char *);
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("1: zeroing xloc %p loc 0x%x\n",
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xloc, loc);
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}
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#endif
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*xloc = (u_char) 0;
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if (loc + 1 < len) {
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/*
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* both xloc and yloc are in same
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* mbuf
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*/
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yloc = 1 + xloc;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf(
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"2: zeroing yloc %p loc 0x%x\n",
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yloc, loc);
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}
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#endif
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*yloc = (u_char) 0;
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} else {
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/* crosses boundary of mbufs */
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yloc = mtod(m->m_next, u_char *);
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf(
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"3: zeroing yloc %p \n", yloc);
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}
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#endif
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*yloc = (u_char) 0;
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}
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}
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loc -= len;
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}
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while (i < cum) {
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c0 = (c0 + *p);
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c1 += c0;
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i++;
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p++;
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}
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m = m->m_next;
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}
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("gen csum final xloc %p yloc %p\n", xloc, yloc);
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}
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#endif
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c1 = (((c0 * (l - n)) - c1) % 255);
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*xloc = (u_char) ((c1 < 0) ? c1 + 255 : c1);
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c1 = (-(int) (c1 + c0)) % 255;
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*yloc = (u_char) (c1 < 0 ? c1 + 255 : c1);
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#ifdef ARGO_DEBUG
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if (argo_debug[D_CHKSUM]) {
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printf("gen csum end \n");
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}
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#endif
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}
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/*
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* FUNCTION: m_datalen
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*
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* PURPOSE: returns length of the mbuf chain.
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* used all over the iso code.
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*
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* RETURNS: integer
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*
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* SIDE EFFECTS: none
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*
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* NOTES:
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*/
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int
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m_datalen(m)
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register struct mbuf *m;
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{
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register int datalen;
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for (datalen = 0; m; m = m->m_next)
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datalen += m->m_len;
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return datalen;
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}
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int
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m_compress(in, out)
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register struct mbuf *in, **out;
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{
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register int datalen = 0;
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int s = splimp();
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if (in->m_next == NULL) {
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*out = in;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress returning 0x%x: A\n", in->m_len);
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}
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#endif
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splx(s);
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return in->m_len;
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}
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MGET((*out), M_DONTWAIT, MT_DATA);
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if ((*out) == NULL) {
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*out = in;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress returning -1: B\n");
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}
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#endif
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splx(s);
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return -1;
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}
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(*out)->m_len = 0;
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(*out)->m_act = NULL;
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while (in) {
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress in %p *out %p\n", in, *out);
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printf("m_compress in: len 0x%x, off %p\n",
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in->m_len, in->m_data);
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printf("m_compress *out: len 0x%x, off %p\n",
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(*out)->m_len, (*out)->m_data);
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}
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#endif
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if (in->m_flags & M_EXT) {
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ASSERT(in->m_len == 0);
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}
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if (in->m_len == 0) {
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in = in->m_next;
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continue;
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}
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if (((*out)->m_flags & M_EXT) == 0) {
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int len;
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len = M_TRAILINGSPACE(*out);
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len = min(len, in->m_len);
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datalen += len;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress copying len %d\n", len);
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}
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#endif
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bcopy(mtod(in, caddr_t), mtod((*out), caddr_t) + (*out)->m_len,
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(unsigned) len);
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(*out)->m_len += len;
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in->m_len -= len;
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continue;
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} else {
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/* (*out) is full */
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if (((*out)->m_next = m_get(M_DONTWAIT, MT_DATA)) == NULL) {
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m_freem(*out);
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*out = in;
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress returning -1: B\n");
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}
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#endif
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splx(s);
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return -1;
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}
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(*out)->m_len = 0;
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(*out)->m_act = NULL;
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*out = (*out)->m_next;
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}
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}
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m_freem(in);
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#ifdef ARGO_DEBUG
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if (argo_debug[D_REQUEST]) {
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printf("m_compress returning 0x%x: A\n", datalen);
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}
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#endif
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splx(s);
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return datalen;
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}
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