[unix-history] / usr / src / sys / netiso / iso_chksum.c

/***********************************************************
		Copyright IBM Corporation 1987

                      All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the name of IBM not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.  

IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
SOFTWARE.

******************************************************************/

/*
 * ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
 */
/* 
 * $Header: iso_chksum.c,v 4.7 88/07/29 15:31:26 nhall Exp $
 * $Source: /usr/argo/sys/netiso/RCS/iso_chksum.c,v $
 *
 * ISO CHECKSUM
 *
 * The checksum generation and check routines are here.
 * The checksum is 2 bytes such that the sum of all the bytes b(i) == 0
 * and the sum of i * b(i) == 0.
 * The whole thing is complicated by the fact that the data are in mbuf
 * chains.
 * Furthermore, there is the possibility of wraparound in the running
 * sums after adding up 4102 octets.  In order to avoid doing a mod
 * operation after EACH add, we have restricted this implementation to 
 * negotiating a maximum of 4096-octets per TPDU (for the transport layer).
 * The routine iso_check_csum doesn't need to know where the checksum
 * octets are.
 * The routine iso_gen_csum takes a pointer to an mbuf chain (logically
 * a chunk of data), an offset into the chunk at which the 2 octets are to
 * be stuffed, and the length of the chunk.  The 2 octets have to be
 * logically adjacent, but may be physically located in separate mbufs.
 */

#ifndef lint
static char *rcsid = "$Header: iso_chksum.c,v 4.7 88/07/29 15:31:26 nhall Exp $";
#endif

#include "../netiso/argo_debug.h"
#include "../h/param.h"
#include "../h/mbuf.h"

#ifndef MNULL
#define MNULL (struct mbuf *)0
#endif MNULL

/*
 * FUNCTION:	iso_check_csum
 *
 * PURPOSE:		To check the checksum of the packet in the mbuf chain (m).
 * 				The total length of the packet is (len).
 * 				Called from tp_input() and clnp_intr()
 *
 * RETURNS:		 TRUE (something non-zero) if there is a checksum error,
 * 			 	 FALSE if there was NO checksum error.
 *
 * SIDE EFFECTS:  none
 *
 * NOTES:		 It might be possible to gain something by optimizing
 *               this routine (unrolling loops, etc). But it is such
 *				 a horrible thing to fiddle with anyway, it probably
 *				 isn't worth it.
 */
int 
iso_check_csum(m, len)
	struct mbuf *m;
	int len;
{
	register u_char *p = mtod(m, u_char *);
	register u_long c0=0, c1=0;
	register int i=0;
	int cum = 0; /* cumulative length */
	int l;

	l = len;
	len = MIN(m->m_len, len);
	i = 0;

	IFDEBUG(D_CHKSUM)
		printf("iso_check_csum: m x%x, l x%x, m->m_len x%x\n", m, l, m->m_len);
	ENDDEBUG

	while( i<l ) {
		cum += len;
		while (i<cum) {
			c0 = c0 + *(p++);
			c1 += c0;
			i++;
		}
		if(i < l) {
			m = m->m_next;
			IFDEBUG(D_CHKSUM)
				printf("iso_check_csum: new mbuf\n");
				if(l-i < m->m_len)
					printf(
					"bad mbuf chain in check csum l 0x%x i 0x%x m_off 0x%x",
						l,i,m->m_off);
			ENDDEBUG
			ASSERT( m != MNULL);
			len = MIN( m->m_len, l-i);
			p = mtod(m, u_char *);
		}
	}
	if ( ((int)c0 % 255) || ((int)c1 % 255) ) {
		IFDEBUG(D_CHKSUM)
			printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x", 
				l, cum, len, i);
		ENDDEBUG
		return ((int)c0 % 255)<<8 | ((int)c1 % 255);
	}
	return 0;
}

/*
 * FUNCTION:	iso_gen_csum
 *
 * PURPOSE:		To generate the checksum of the packet in the mbuf chain (m).
 * 				The first of the 2 (logically) adjacent checksum bytes 
 *				(x and y) go at offset (n).
 * 				(n) is an offset relative to the beginning of the data, 
 *				not the beginning of the mbuf.
 * 				(l) is the length of the total mbuf chain's data.
 * 				Called from tp_emit(), tp_error_emit()
 *				clnp_emit_er(), clnp_forward(), clnp_output().
 *
 * RETURNS:		Rien
 *
 * SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
 *
 * NOTES:		Ditto the note for iso_check_csum().
 */

void
iso_gen_csum(m,n,l)
	struct mbuf *m;
	int n; /* offset of 2 checksum bytes */
	int l;
{
#ifdef lint
	register u_char *p = (u_char *)((int)m + m->m_off);
#else
	register u_char *p = mtod(m, u_char *);
#endif
	register int c0=0, c1=0;
	register int i=0;
	int loc = n++, len=0; /* n is position, loc is offset */
	u_char *xloc;
	u_char *yloc;
	int cum=0;	/* cum == cumulative length */

	IFDEBUG(D_CHKSUM)
		printf("enter gen csum m 0x%x n 0x%x l 0x%x\n",m, n-1 ,l );
	ENDDEBUG

	while(i < l) {
		len = MIN(m->m_len, CLBYTES);
		/* RAH: don't cksum more than l bytes */
		len = MIN(len, l);

		cum +=len;
		p = mtod(m, u_char *);

		if(loc>=0) {
			if (loc < len) {
				xloc = ((u_char *)((int)(m) + (m)->m_off + loc));
				IFDEBUG(D_CHKSUM)
					printf("1: zeroing xloc 0x%x loc 0x%x\n",xloc, loc );
				ENDDEBUG
				*xloc = (u_char)0;
				if (loc+1 < len) {
					/* both xloc and yloc are in same mbuf */
					yloc = ((u_char *)((int)(m) + (m)->m_off + loc + 1));
					IFDEBUG(D_CHKSUM)
						printf("2: zeroing yloc 0x%x loc 0x%x\n",yloc, loc );
					ENDDEBUG
					*yloc = (u_char)0;
				} else {
					/* crosses boundary of mbufs */
					yloc = ((u_char *)((int)(m->m_next) + (m->m_next)->m_off));
					IFDEBUG(D_CHKSUM)
						printf("3: zeroing yloc 0x%x \n",yloc );
					ENDDEBUG
					*yloc = (u_char)0;
				}
			}
			loc -= len;
		}

		while(i < cum) {
			c0 = (c0 + *p);
			c1 += c0 ;
			i++; 
			p++;
		}
		m = m->m_next;
	}
	IFDEBUG(D_CHKSUM)
		printf("gen csum final xloc 0x%x yloc 0x%x\n",xloc, yloc );
	ENDDEBUG

	c1 = (((c0 * (l-n))-c1)%255) ;
	*xloc = (u_char) ((c1 < 0)? c1+255 : c1);

	c1 = (-(int)(c1+c0))%255;
	*yloc = (u_char) (c1 < 0? c1 + 255 : c1);

	IFDEBUG(D_CHKSUM)
		printf("gen csum end \n");
	ENDDEBUG
}

struct mbuf  *
m_append(head, m)
	struct mbuf *head, *m;
{
	register struct mbuf *n;

	if (m == 0)
		return head;
	if (head == 0)
		return m;
	n = head;
	while (n->m_next)
		n = n->m_next;
	n->m_next = m;
	return head;
}
/*
 * FUNCTION:	m_datalen
 *
 * PURPOSE:		returns length of the mbuf chain.
 * 				used all over the iso code.
 *
 * RETURNS:		integer
 *
 * SIDE EFFECTS: none
 *
 * NOTES:		
 */

int
m_datalen (morig)
	struct mbuf *morig;
{ 	
	int	s = splimp();
	register struct mbuf *n=morig;
	register int datalen = 0;

	if( morig == (struct mbuf *)0)
		return 0;
	for(;;) {
		datalen += n->m_len;
		if (n->m_next == (struct mbuf *)0 ) {
			break;
		}
		n = n->m_next;
	}
	splx(s);
	return datalen;
}

int
m_compress(in, out)
	register struct mbuf *in, **out;
{
	register 	int datalen = 0;
	int	s = splimp();

	if( in->m_next == MNULL ) {
		*out = in;
		IFDEBUG(D_REQUEST)
			printf("m_compress returning 0x%x: A\n", in->m_len);
		ENDDEBUG
		splx(s);
		return in->m_len;
	}
	MGET((*out), M_DONTWAIT, MT_DATA);
	if((*out) == MNULL) {
		*out = in;
		IFDEBUG(D_REQUEST)
			printf("m_compress returning -1: B\n");
		ENDDEBUG
		splx(s);
		return -1; 
	}
	(*out)->m_len = 0;
	(*out)->m_act = MNULL;

	while (in) {
		IFDEBUG(D_REQUEST)
			printf("m_compress in 0x%x *out 0x%x\n", in, *out);
			printf("m_compress in: len 0x%x, off 0x%x\n", in->m_len, in->m_off);
			printf("m_compress *out: len 0x%x, off 0x%x\n", (*out)->m_len, 
				(*out)->m_off);
		ENDDEBUG
		if ( in->m_off >= MMAXOFF) {
			ASSERT(in->m_len == 0);
		}
		if ( in->m_len == 0) {
			in = in->m_next;
			continue;
		}
		if ((*out)->m_off < MMAXOFF) {
			int len;

		    len = MMAXOFF - ((*out)->m_off + (*out)->m_len);
			len = MIN(len, in->m_len);
			datalen += len;

			IFDEBUG(D_REQUEST)
				printf("m_compress copying len %d\n", len);
			ENDDEBUG
			bcopy(mtod(in, caddr_t), mtod((*out), caddr_t) + (*out)->m_len, len);

			(*out)->m_len += len;
			in->m_len -= len;
			continue;
		} else {
			/* (*out) is full */
			if(( (*out)->m_next = m_get(M_DONTWAIT, MT_DATA) ) == MNULL) {
				m_freem(*out);
				*out = in;
				IFDEBUG(D_REQUEST)
					printf("m_compress returning -1: B\n");
				ENDDEBUG
				splx(s);
				return -1;
			}
			(*out)->m_len = 0;
			(*out)->m_act = MNULL;
			*out = (*out)->m_next;
		}
	}
	m_freem(in);
	IFDEBUG(D_REQUEST)
		printf("m_compress returning 0x%x: A\n", datalen);
	ENDDEBUG
	splx(s);
	return datalen;
}
Commit	Line	Data
ee8eb34a KS	1	/***********************************************************
	2	Copyright IBM Corporation 1987
	3
	4	All Rights Reserved
	5
	6	Permission to use, copy, modify, and distribute this software and its
	7	documentation for any purpose and without fee is hereby granted,
	8	provided that the above copyright notice appear in all copies and that
	9	both that copyright notice and this permission notice appear in
	10	supporting documentation, and that the name of IBM not be
	11	used in advertising or publicity pertaining to distribution of the
	12	software without specific, written prior permission.
	13
	14	IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
	15	ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
	16	IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
	17	ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	18	WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
	19	ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
	20	SOFTWARE.
	21
	22	******************************************************************/
	23
	24	/*
	25	* ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
	26	*/
	27	/*
	28	* $Header: iso_chksum.c,v 4.7 88/07/29 15:31:26 nhall Exp $
	29	* $Source: /usr/argo/sys/netiso/RCS/iso_chksum.c,v $
	30	*
	31	* ISO CHECKSUM
	32	*
	33	* The checksum generation and check routines are here.
	34	* The checksum is 2 bytes such that the sum of all the bytes b(i) == 0
	35	* and the sum of i * b(i) == 0.
	36	* The whole thing is complicated by the fact that the data are in mbuf
	37	* chains.
	38	* Furthermore, there is the possibility of wraparound in the running
	39	* sums after adding up 4102 octets. In order to avoid doing a mod
	40	* operation after EACH add, we have restricted this implementation to
	41	* negotiating a maximum of 4096-octets per TPDU (for the transport layer).
	42	* The routine iso_check_csum doesn't need to know where the checksum
	43	* octets are.
	44	* The routine iso_gen_csum takes a pointer to an mbuf chain (logically
	45	* a chunk of data), an offset into the chunk at which the 2 octets are to
	46	* be stuffed, and the length of the chunk. The 2 octets have to be
	47	* logically adjacent, but may be physically located in separate mbufs.
	48	*/
	49
	50	#ifndef lint
	51	static char *rcsid = "$Header: iso_chksum.c,v 4.7 88/07/29 15:31:26 nhall Exp $";
	52	#endif
	53
	54	#include "../netiso/argo_debug.h"
	55	#include "../h/param.h"
	56	#include "../h/mbuf.h"
	57
	58	#ifndef MNULL
	59	#define MNULL (struct mbuf *)0
	60	#endif MNULL
	61
	62	/*
	63	* FUNCTION: iso_check_csum
	64	*
65	* PURPOSE: To check the checksum of the packet in the mbuf chain (m).
66	* The total length of the packet is (len).
67	* Called from tp_input() and clnp_intr()
68	*
69	* RETURNS: TRUE (something non-zero) if there is a checksum error,
70	* FALSE if there was NO checksum error.
71	*
72	* SIDE EFFECTS: none
73	*
74	* NOTES: It might be possible to gain something by optimizing
75	* this routine (unrolling loops, etc). But it is such
76	* a horrible thing to fiddle with anyway, it probably
77	* isn't worth it.
78	*/
79	int
80	iso_check_csum(m, len)
81	struct mbuf *m;
82	int len;
83	{
84	register u_char p = mtod(m, u_char );
85	register u_long c0=0, c1=0;
86	register int i=0;
87	int cum = 0; /* cumulative length */
88	int l;
89
90	l = len;
91	len = MIN(m->m_len, len);
92	i = 0;
93
94	IFDEBUG(D_CHKSUM)
95	printf("iso_check_csum: m x%x, l x%x, m->m_len x%x\n", m, l, m->m_len);
96	ENDDEBUG
97
98	while( i<l ) {
99	cum += len;
100	while (i<cum) {
101	c0 = c0 + *(p++);
102	c1 += c0;
103	i++;
104	}
105	if(i < l) {
106	m = m->m_next;
107	IFDEBUG(D_CHKSUM)
108	printf("iso_check_csum: new mbuf\n");
109	if(l-i < m->m_len)
110	printf(
111	"bad mbuf chain in check csum l 0x%x i 0x%x m_off 0x%x",
112	l,i,m->m_off);
113	ENDDEBUG
114	ASSERT( m != MNULL);
115	len = MIN( m->m_len, l-i);
116	p = mtod(m, u_char *);
117	}
118	}
119	if ( ((int)c0 % 255) \|\| ((int)c1 % 255) ) {
120	IFDEBUG(D_CHKSUM)
121	printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x",
122	l, cum, len, i);
123	ENDDEBUG
124	return ((int)c0 % 255)<<8 \| ((int)c1 % 255);
125	}
126	return 0;
127	}
128
129	/*
130	* FUNCTION: iso_gen_csum
131	*
132	* PURPOSE: To generate the checksum of the packet in the mbuf chain (m).
133	* The first of the 2 (logically) adjacent checksum bytes
134	* (x and y) go at offset (n).
135	* (n) is an offset relative to the beginning of the data,
136	* not the beginning of the mbuf.
137	* (l) is the length of the total mbuf chain's data.
138	* Called from tp_emit(), tp_error_emit()
139	* clnp_emit_er(), clnp_forward(), clnp_output().
140	*
141	* RETURNS: Rien
142	*
143	* SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
144	*
145	* NOTES: Ditto the note for iso_check_csum().
146	*/
147
148	void
149	iso_gen_csum(m,n,l)
150	struct mbuf *m;
151	int n; /* offset of 2 checksum bytes */
152	int l;
153	{
154	#ifdef lint
155	register u_char p = (u_char )((int)m + m->m_off);
156	#else
157	register u_char p = mtod(m, u_char );
158	#endif
159	register int c0=0, c1=0;
160	register int i=0;
161	int loc = n++, len=0; /* n is position, loc is offset */
162	u_char *xloc;
163	u_char *yloc;
164	int cum=0; /* cum == cumulative length */
165
166	IFDEBUG(D_CHKSUM)
167	printf("enter gen csum m 0x%x n 0x%x l 0x%x\n",m, n-1 ,l );
168	ENDDEBUG
169
170	while(i < l) {
171	len = MIN(m->m_len, CLBYTES);
172	/* RAH: don't cksum more than l bytes */
173	len = MIN(len, l);
174
175	cum +=len;
176	p = mtod(m, u_char *);
177
178	if(loc>=0) {
179	if (loc < len) {
180	xloc = ((u_char *)((int)(m) + (m)->m_off + loc));
181	IFDEBUG(D_CHKSUM)
182	printf("1: zeroing xloc 0x%x loc 0x%x\n",xloc, loc );
183	ENDDEBUG
184	*xloc = (u_char)0;
185	if (loc+1 < len) {
186	/* both xloc and yloc are in same mbuf */
187	yloc = ((u_char *)((int)(m) + (m)->m_off + loc + 1));
188	IFDEBUG(D_CHKSUM)
189	printf("2: zeroing yloc 0x%x loc 0x%x\n",yloc, loc );
190	ENDDEBUG
191	*yloc = (u_char)0;
192	} else {
193	/* crosses boundary of mbufs */
194	yloc = ((u_char *)((int)(m->m_next) + (m->m_next)->m_off));
195	IFDEBUG(D_CHKSUM)
196	printf("3: zeroing yloc 0x%x \n",yloc );
197	ENDDEBUG
198	*yloc = (u_char)0;
199	}
200	}
201	loc -= len;
202	}
203
204	while(i < cum) {
205	c0 = (c0 + *p);
206	c1 += c0 ;
207	i++;
208	p++;
209	}
210	m = m->m_next;
211	}
212	IFDEBUG(D_CHKSUM)
213	printf("gen csum final xloc 0x%x yloc 0x%x\n",xloc, yloc );
214	ENDDEBUG
215
216	c1 = (((c0 * (l-n))-c1)%255) ;
217	*xloc = (u_char) ((c1 < 0)? c1+255 : c1);
218
219	c1 = (-(int)(c1+c0))%255;
220	*yloc = (u_char) (c1 < 0? c1 + 255 : c1);
221
222	IFDEBUG(D_CHKSUM)
223	printf("gen csum end \n");
224	ENDDEBUG
225	}
226
227	struct mbuf *
228	m_append(head, m)
229	struct mbuf head, m;
230	{
231	register struct mbuf *n;
232
233	if (m == 0)
234	return head;
235	if (head == 0)
236	return m;
237	n = head;
238	while (n->m_next)
239	n = n->m_next;
240	n->m_next = m;
241	return head;
242	}
243	/*
244	* FUNCTION: m_datalen
245	*
246	* PURPOSE: returns length of the mbuf chain.
247	* used all over the iso code.
248	*
249	* RETURNS: integer
250	*
251	* SIDE EFFECTS: none
252	*
253	* NOTES:
254	*/
255
256	int
257	m_datalen (morig)
258	struct mbuf *morig;
259	{
260	int s = splimp();
261	register struct mbuf *n=morig;
262	register int datalen = 0;
263
264	if( morig == (struct mbuf *)0)
265	return 0;
266	for(;;) {
267	datalen += n->m_len;
268	if (n->m_next == (struct mbuf *)0 ) {
269	break;
270	}
271	n = n->m_next;
272	}
273	splx(s);
274	return datalen;
275	}
276
277	int
278	m_compress(in, out)
279	register struct mbuf in, *out;
280	{
281	register int datalen = 0;
282	int s = splimp();
283
284	if( in->m_next == MNULL ) {
285	*out = in;
286	IFDEBUG(D_REQUEST)
287	printf("m_compress returning 0x%x: A\n", in->m_len);
288	ENDDEBUG
289	splx(s);
290	return in->m_len;
291	}
292	MGET((*out), M_DONTWAIT, MT_DATA);
293	if((*out) == MNULL) {
294	*out = in;
295	IFDEBUG(D_REQUEST)
296	printf("m_compress returning -1: B\n");
297	ENDDEBUG
298	splx(s);
299	return -1;
300	}
301	(*out)->m_len = 0;
302	(*out)->m_act = MNULL;
303
304	while (in) {
305	IFDEBUG(D_REQUEST)
306	printf("m_compress in 0x%x out 0x%x\n", in, out);
307	printf("m_compress in: len 0x%x, off 0x%x\n", in->m_len, in->m_off);
308	printf("m_compress out: len 0x%x, off 0x%x\n", (out)->m_len,
309	(*out)->m_off);
310	ENDDEBUG
311	if ( in->m_off >= MMAXOFF) {
312	ASSERT(in->m_len == 0);
313	}
314	if ( in->m_len == 0) {
315	in = in->m_next;
316	continue;
317	}
318	if ((*out)->m_off < MMAXOFF) {
319	int len;
320
321	len = MMAXOFF - ((out)->m_off + (out)->m_len);
322	len = MIN(len, in->m_len);
323	datalen += len;
324
325	IFDEBUG(D_REQUEST)
326	printf("m_compress copying len %d\n", len);
327	ENDDEBUG
328	bcopy(mtod(in, caddr_t), mtod((out), caddr_t) + (out)->m_len, len);
329
330	(*out)->m_len += len;
331	in->m_len -= len;
332	continue;
333	} else {
334	/* (out) is full /
335	if(( (*out)->m_next = m_get(M_DONTWAIT, MT_DATA) ) == MNULL) {
336	m_freem(*out);
337	*out = in;
338	IFDEBUG(D_REQUEST)
339	printf("m_compress returning -1: B\n");
340	ENDDEBUG
341	splx(s);
342	return -1;
343	}
344	(*out)->m_len = 0;
345	(*out)->m_act = MNULL;
346	out = (out)->m_next;
347	}
348	}
349	m_freem(in);
350	IFDEBUG(D_REQUEST)
351	printf("m_compress returning 0x%x: A\n", datalen);
352	ENDDEBUG
353	splx(s);
354	return datalen;
355	}