1/*	$NetBSD: iso_chksum.c,v 1.22 2006/04/14 23:53:53 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 *	@(#)iso_chksum.c	8.1 (Berkeley) 6/10/93
32 */
33
34/***********************************************************
35		Copyright IBM Corporation 1987
36
37                      All Rights Reserved
38
39Permission to use, copy, modify, and distribute this software and its
40documentation for any purpose and without fee is hereby granted,
41provided that the above copyright notice appear in all copies and that
42both that copyright notice and this permission notice appear in
43supporting documentation, and that the name of IBM not be
44used in advertising or publicity pertaining to distribution of the
45software without specific, written prior permission.
46
47IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
48ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
49IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
50ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
51WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
52ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
53SOFTWARE.
54
55******************************************************************/
56
57/*
58 * ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
59 */
60/*
61 * ISO CHECKSUM
62 *
63 * The checksum generation and check routines are here. The checksum is 2 bytes
64 * such that the sum of all the bytes b(i) == 0 and the sum of i * b(i) == 0.
65 * The whole thing is complicated by the fact that the data are in mbuf
66 * chains. Furthermore, there is the possibility of wraparound in the running
67 * sums after adding up 4102 octets.  In order to avoid doing a mod operation
68 * after EACH add, we have restricted this implementation to negotiating a
69 * maximum of 4096-octets per TPDU (for the transport layer). The routine
70 * iso_check_csum doesn't need to know where the checksum octets are. The
71 * routine iso_gen_csum takes a pointer to an mbuf chain (logically a chunk
72 * of data), an offset into the chunk at which the 2 octets are to be
73 * stuffed, and the length of the chunk.  The 2 octets have to be logically
74 * adjacent, but may be physically located in separate mbufs.
75 */
76
77#include <sys/cdefs.h>
78__KERNEL_RCSID(1, "$NetBSD: iso_chksum.c,v 1.22 2006/04/14 23:53:53 christos Exp $");
79
80#include "opt_iso.h"
81
82#ifdef ISO
83#include <sys/param.h>
84#include <sys/systm.h>
85#include <sys/mbuf.h>
86#include <sys/socket.h>
87
88#include <uvm/uvm_extern.h>
89
90#include <net/if.h>
91#include <netiso/argo_debug.h>
92#include <netiso/iso.h>
93#include <netiso/iso_var.h>
94#endif /* ISO */
95
96/*
97 * FUNCTION:	iso_check_csum
98 *
99 * PURPOSE:	To check the checksum of the packet in the mbuf chain (m).
100 * 			The total length of the packet is (len).
101 * 			Called from tp_input() and clnp_intr()
102 *
103 * RETURNS:	 TRUE (something non-zero) if there is a checksum error,
104 * 		 FALSE if there was NO checksum error.
105 *
106 * SIDE EFFECTS:  none
107 *
108 * NOTES:	 It might be possible to gain something by optimizing
109 *               this routine (unrolling loops, etc). But it is such
110 *		 a horrible thing to fiddle with anyway, it probably
111 *		 isn't worth it.
112 */
113int
114iso_check_csum(struct mbuf *m, int len)
115{
116	u_char *p = mtod(m, u_char *);
117	u_long c0 = 0, c1 = 0;
118	int    i = 0;
119	int             cum = 0;/* cumulative length */
120	int             l;
121
122	l = len;
123	len = min(m->m_len, len);
124	i = 0;
125
126#ifdef ARGO_DEBUG
127	if (argo_debug[D_CHKSUM]) {
128		printf("iso_check_csum: m %p, l x%x, m->m_len x%x\n",
129		    m, l, m->m_len);
130	}
131#endif
132
133	while (i < l) {
134		cum += len;
135		while (i < cum) {
136			c0 = c0 + *(p++);
137			c1 += c0;
138			i++;
139		}
140		if (i < l) {
141			m = m->m_next;
142#ifdef ARGO_DEBUG
143			if (argo_debug[D_CHKSUM]) {
144				printf("iso_check_csum: new mbuf\n");
145				if (l - i < m->m_len)
146					printf(
147		       "bad mbuf chain in check csum l 0x%x i 0x%x m_data %p",
148					       l, i, m->m_data);
149			}
150#endif
151			ASSERT(m != NULL);
152			len = min(m->m_len, l - i);
153			p = mtod(m, u_char *);
154		}
155	}
156	if (((int) c0 % 255) || ((int) c1 % 255)) {
157#ifdef ARGO_DEBUG
158		if (argo_debug[D_CHKSUM]) {
159			printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x",
160			    l, cum, len, i);
161		}
162#endif
163		return ((int) c0 % 255) << 8 | ((int) c1 % 255);
164	}
165	return 0;
166}
167
168/*
169 * FUNCTION:	iso_gen_csum
170 *
171 * PURPOSE:	To generate the checksum of the packet in the mbuf chain (m).
172 * 		The first of the 2 (logically) adjacent checksum bytes
173 *		(x and y) go at offset (n).
174 * 		(n) is an offset relative to the beginning of the data,
175 *		not the beginning of the mbuf.
176 * 		(l) is the length of the total mbuf chain's data.
177 * 		Called from tp_emit(), tp_error_emit()
178 *		clnp_emit_er(), clnp_forward(), clnp_output().
179 *
180 * RETURNS:	Rien
181 *
182 * SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
183 *
184 * NOTES:	Ditto the note for iso_check_csum().
185 */
186
187void
188iso_gen_csum(
189	struct mbuf    *m,
190	int             n,	/* offset of 2 checksum bytes */
191	int             l)
192{
193	u_char *p = mtod(m, u_char *);
194	int    c0 = 0, c1 = 0;
195	int    i = 0;
196	int             loc = n++, len = 0;	/* n is position, loc is
197						 * offset */
198	u_char         *xloc = NULL;
199	u_char         *yloc = NULL;
200	int             cum = 0;/* cum == cumulative length */
201
202#ifdef ARGO_DEBUG
203	if (argo_debug[D_CHKSUM]) {
204		printf("enter gen csum m %p n 0x%x l 0x%x\n",
205		    m, n - 1, l);
206	}
207#endif
208
209	while (i < l) {
210		len = min(m->m_len, PAGE_SIZE);
211		/* RAH: don't cksum more than l bytes */
212		len = min(len, l - i);
213
214		cum += len;
215		p = mtod(m, u_char *);
216
217		if (loc >= 0) {
218			if (loc < len) {
219				xloc = loc + mtod(m, u_char *);
220#ifdef ARGO_DEBUG
221				if (argo_debug[D_CHKSUM]) {
222					printf("1: zeroing xloc %p loc 0x%x\n",
223					    xloc, loc);
224				}
225#endif
226				*xloc = (u_char) 0;
227				if (loc + 1 < len) {
228					/*
229					 * both xloc and yloc are in same
230					 * mbuf
231					 */
232					yloc = 1 + xloc;
233#ifdef ARGO_DEBUG
234					if (argo_debug[D_CHKSUM]) {
235						printf(
236					"2: zeroing yloc %p loc 0x%x\n",
237					yloc, loc);
238					}
239#endif
240					*yloc = (u_char) 0;
241				} else {
242					/* crosses boundary of mbufs */
243					yloc = mtod(m->m_next, u_char *);
244#ifdef ARGO_DEBUG
245					if (argo_debug[D_CHKSUM]) {
246						printf(
247					    "3: zeroing yloc %p \n", yloc);
248					}
249#endif
250					*yloc = (u_char) 0;
251				}
252			}
253			loc -= len;
254		}
255		while (i < cum) {
256			c0 = (c0 + *p);
257			c1 += c0;
258			i++;
259			p++;
260		}
261		m = m->m_next;
262	}
263#ifdef ARGO_DEBUG
264	if (argo_debug[D_CHKSUM]) {
265		printf("gen csum final xloc %p yloc %p\n", xloc, yloc);
266	}
267#endif
268
269	c1 = (((c0 * (l - n)) - c1) % 255);
270	if (xloc)
271		*xloc = (u_char) ((c1 < 0) ? c1 + 255 : c1);
272
273	c1 = (-(int) (c1 + c0)) % 255;
274	if (yloc)
275		*yloc = (u_char) (c1 < 0 ? c1 + 255 : c1);
276
277#ifdef ARGO_DEBUG
278	if (argo_debug[D_CHKSUM]) {
279		printf("gen csum end \n");
280	}
281#endif
282}
283
284/*
285 * FUNCTION:	m_datalen
286 *
287 * PURPOSE:	returns length of the mbuf chain.
288 * 		used all over the iso code.
289 *
290 * RETURNS:	integer
291 *
292 * SIDE EFFECTS: none
293 *
294 * NOTES:
295 */
296
297int
298m_datalen(struct mbuf *m)
299{
300	int    datalen;
301
302	for (datalen = 0; m; m = m->m_next)
303		datalen += m->m_len;
304	return datalen;
305}
306
307int
308m_compress(struct mbuf *in, struct mbuf **out)
309{
310	int    datalen = 0;
311	int             s = splnet();
312
313	if (in->m_next == NULL) {
314		*out = in;
315#ifdef ARGO_DEBUG
316		if (argo_debug[D_REQUEST]) {
317			printf("m_compress returning 0x%x: A\n", in->m_len);
318		}
319#endif
320		splx(s);
321		return in->m_len;
322	}
323	MGET((*out), M_DONTWAIT, MT_DATA);
324	if ((*out) == NULL) {
325		*out = in;
326#ifdef ARGO_DEBUG
327		if (argo_debug[D_REQUEST]) {
328			printf("m_compress returning -1: B\n");
329		}
330#endif
331		splx(s);
332		return -1;
333	}
334	(*out)->m_len = 0;
335	(*out)->m_nextpkt = NULL;
336
337	while (in) {
338#ifdef ARGO_DEBUG
339		if (argo_debug[D_REQUEST]) {
340			printf("m_compress in %p *out %p\n", in, *out);
341			printf("m_compress in: len 0x%x, off %p\n",
342			    in->m_len, in->m_data);
343			printf("m_compress *out: len 0x%x, off %p\n",
344			    (*out)->m_len, (*out)->m_data);
345		}
346#endif
347		if (in->m_flags & M_EXT) {
348			ASSERT(in->m_len == 0);
349		}
350		if (in->m_len == 0) {
351			in = in->m_next;
352			continue;
353		}
354		if (((*out)->m_flags & M_EXT) == 0) {
355			int             len;
356
357			len = M_TRAILINGSPACE(*out);
358			len = min(len, in->m_len);
359			datalen += len;
360
361#ifdef ARGO_DEBUG
362			if (argo_debug[D_REQUEST]) {
363				printf("m_compress copying len %d\n", len);
364			}
365#endif
366			memcpy(mtod((*out), char *) + (*out)->m_len,
367			    mtod(in, void *), (unsigned) len);
368
369			(*out)->m_len += len;
370			in->m_len -= len;
371			continue;
372		} else {
373			/* (*out) is full */
374			if (((*out)->m_next = m_get(M_DONTWAIT, MT_DATA)) == NULL) {
375				m_freem(*out);
376				*out = in;
377#ifdef ARGO_DEBUG
378				if (argo_debug[D_REQUEST]) {
379					printf("m_compress returning -1: B\n");
380				}
381#endif
382				splx(s);
383				return -1;
384			}
385			(*out)->m_len = 0;
386			(*out)->m_nextpkt = NULL;
387			*out = (*out)->m_next;
388		}
389	}
390	m_freem(in);
391#ifdef ARGO_DEBUG
392	if (argo_debug[D_REQUEST]) {
393		printf("m_compress returning 0x%x: A\n", datalen);
394	}
395#endif
396	splx(s);
397	return datalen;
398}
399