1 /* $NetBSD: iso_chksum.c,v 1.18 2003/08/07 16:33:36 agc 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
39 Permission to use, copy, modify, and distribute this software and its
40 documentation for any purpose and without fee is hereby granted,
41 provided that the above copyright notice appear in all copies and that
42 both that copyright notice and this permission notice appear in
43 supporting documentation, and that the name of IBM not be
44 used in advertising or publicity pertaining to distribution of the
45 software without specific, written prior permission.
46
47 IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
48 ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
49 IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
50 ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
51 WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
52 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
53 SOFTWARE.
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 1.18 2003/08/07 16:33:36 agc 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 */
113 int
114 iso_check_csum(m, len)
115 struct mbuf *m;
116 int len;
117 {
118 u_char *p = mtod(m, u_char *);
119 u_long c0 = 0, c1 = 0;
120 int i = 0;
121 int cum = 0;/* cumulative length */
122 int l;
123
124 l = len;
125 len = min(m->m_len, len);
126 i = 0;
127
128 #ifdef ARGO_DEBUG
129 if (argo_debug[D_CHKSUM]) {
130 printf("iso_check_csum: m %p, l x%x, m->m_len x%x\n",
131 m, l, m->m_len);
132 }
133 #endif
134
135 while (i < l) {
136 cum += len;
137 while (i < cum) {
138 c0 = c0 + *(p++);
139 c1 += c0;
140 i++;
141 }
142 if (i < l) {
143 m = m->m_next;
144 #ifdef ARGO_DEBUG
145 if (argo_debug[D_CHKSUM]) {
146 printf("iso_check_csum: new mbuf\n");
147 if (l - i < m->m_len)
148 printf(
149 "bad mbuf chain in check csum l 0x%x i 0x%x m_data %p",
150 l, i, m->m_data);
151 }
152 #endif
153 ASSERT(m != NULL);
154 len = min(m->m_len, l - i);
155 p = mtod(m, u_char *);
156 }
157 }
158 if (((int) c0 % 255) || ((int) c1 % 255)) {
159 #ifdef ARGO_DEBUG
160 if (argo_debug[D_CHKSUM]) {
161 printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x",
162 l, cum, len, i);
163 }
164 #endif
165 return ((int) c0 % 255) << 8 | ((int) c1 % 255);
166 }
167 return 0;
168 }
169
170 /*
171 * FUNCTION: iso_gen_csum
172 *
173 * PURPOSE: To generate the checksum of the packet in the mbuf chain (m).
174 * The first of the 2 (logically) adjacent checksum bytes
175 * (x and y) go at offset (n).
176 * (n) is an offset relative to the beginning of the data,
177 * not the beginning of the mbuf.
178 * (l) is the length of the total mbuf chain's data.
179 * Called from tp_emit(), tp_error_emit()
180 * clnp_emit_er(), clnp_forward(), clnp_output().
181 *
182 * RETURNS: Rien
183 *
184 * SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
185 *
186 * NOTES: Ditto the note for iso_check_csum().
187 */
188
189 void
190 iso_gen_csum(m, n, l)
191 struct mbuf *m;
192 int n; /* offset of 2 checksum bytes */
193 int l;
194 {
195 u_char *p = mtod(m, u_char *);
196 int c0 = 0, c1 = 0;
197 int i = 0;
198 int loc = n++, len = 0; /* n is position, loc is
199 * offset */
200 u_char *xloc = NULL;
201 u_char *yloc = NULL;
202 int cum = 0;/* cum == cumulative length */
203
204 #ifdef ARGO_DEBUG
205 if (argo_debug[D_CHKSUM]) {
206 printf("enter gen csum m %p n 0x%x l 0x%x\n",
207 m, n - 1, l);
208 }
209 #endif
210
211 while (i < l) {
212 len = min(m->m_len, PAGE_SIZE);
213 /* RAH: don't cksum more than l bytes */
214 len = min(len, l - i);
215
216 cum += len;
217 p = mtod(m, u_char *);
218
219 if (loc >= 0) {
220 if (loc < len) {
221 xloc = loc + mtod(m, u_char *);
222 #ifdef ARGO_DEBUG
223 if (argo_debug[D_CHKSUM]) {
224 printf("1: zeroing xloc %p loc 0x%x\n",
225 xloc, loc);
226 }
227 #endif
228 *xloc = (u_char) 0;
229 if (loc + 1 < len) {
230 /*
231 * both xloc and yloc are in same
232 * mbuf
233 */
234 yloc = 1 + xloc;
235 #ifdef ARGO_DEBUG
236 if (argo_debug[D_CHKSUM]) {
237 printf(
238 "2: zeroing yloc %p loc 0x%x\n",
239 yloc, loc);
240 }
241 #endif
242 *yloc = (u_char) 0;
243 } else {
244 /* crosses boundary of mbufs */
245 yloc = mtod(m->m_next, u_char *);
246 #ifdef ARGO_DEBUG
247 if (argo_debug[D_CHKSUM]) {
248 printf(
249 "3: zeroing yloc %p \n", yloc);
250 }
251 #endif
252 *yloc = (u_char) 0;
253 }
254 }
255 loc -= len;
256 }
257 while (i < cum) {
258 c0 = (c0 + *p);
259 c1 += c0;
260 i++;
261 p++;
262 }
263 m = m->m_next;
264 }
265 #ifdef ARGO_DEBUG
266 if (argo_debug[D_CHKSUM]) {
267 printf("gen csum final xloc %p yloc %p\n", xloc, yloc);
268 }
269 #endif
270
271 c1 = (((c0 * (l - n)) - c1) % 255);
272 *xloc = (u_char) ((c1 < 0) ? c1 + 255 : c1);
273
274 c1 = (-(int) (c1 + c0)) % 255;
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
297 int
298 m_datalen(m)
299 struct mbuf *m;
300 {
301 int datalen;
302
303 for (datalen = 0; m; m = m->m_next)
304 datalen += m->m_len;
305 return datalen;
306 }
307
308 int
309 m_compress(in, out)
310 struct mbuf *in, **out;
311 {
312 int datalen = 0;
313 int s = splnet();
314
315 if (in->m_next == NULL) {
316 *out = in;
317 #ifdef ARGO_DEBUG
318 if (argo_debug[D_REQUEST]) {
319 printf("m_compress returning 0x%x: A\n", in->m_len);
320 }
321 #endif
322 splx(s);
323 return in->m_len;
324 }
325 MGET((*out), M_DONTWAIT, MT_DATA);
326 if ((*out) == NULL) {
327 *out = in;
328 #ifdef ARGO_DEBUG
329 if (argo_debug[D_REQUEST]) {
330 printf("m_compress returning -1: B\n");
331 }
332 #endif
333 splx(s);
334 return -1;
335 }
336 (*out)->m_len = 0;
337 (*out)->m_nextpkt = NULL;
338
339 while (in) {
340 #ifdef ARGO_DEBUG
341 if (argo_debug[D_REQUEST]) {
342 printf("m_compress in %p *out %p\n", in, *out);
343 printf("m_compress in: len 0x%x, off %p\n",
344 in->m_len, in->m_data);
345 printf("m_compress *out: len 0x%x, off %p\n",
346 (*out)->m_len, (*out)->m_data);
347 }
348 #endif
349 if (in->m_flags & M_EXT) {
350 ASSERT(in->m_len == 0);
351 }
352 if (in->m_len == 0) {
353 in = in->m_next;
354 continue;
355 }
356 if (((*out)->m_flags & M_EXT) == 0) {
357 int len;
358
359 len = M_TRAILINGSPACE(*out);
360 len = min(len, in->m_len);
361 datalen += len;
362
363 #ifdef ARGO_DEBUG
364 if (argo_debug[D_REQUEST]) {
365 printf("m_compress copying len %d\n", len);
366 }
367 #endif
368 bcopy(mtod(in, caddr_t), mtod((*out), caddr_t) + (*out)->m_len,
369 (unsigned) len);
370
371 (*out)->m_len += len;
372 in->m_len -= len;
373 continue;
374 } else {
375 /* (*out) is full */
376 if (((*out)->m_next = m_get(M_DONTWAIT, MT_DATA)) == NULL) {
377 m_freem(*out);
378 *out = in;
379 #ifdef ARGO_DEBUG
380 if (argo_debug[D_REQUEST]) {
381 printf("m_compress returning -1: B\n");
382 }
383 #endif
384 splx(s);
385 return -1;
386 }
387 (*out)->m_len = 0;
388 (*out)->m_nextpkt = NULL;
389 *out = (*out)->m_next;
390 }
391 }
392 m_freem(in);
393 #ifdef ARGO_DEBUG
394 if (argo_debug[D_REQUEST]) {
395 printf("m_compress returning 0x%x: A\n", datalen);
396 }
397 #endif
398 splx(s);
399 return datalen;
400 }
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