[unix-history] / sys / netiso / clnp_er.c

/*-
 * Copyright (c) 1991 The Regents of the University of California.
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	from: @(#)clnp_er.c	7.7 (Berkeley) 5/6/91
 *	$Id$
 */

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

#include "param.h"
#include "mbuf.h"
#include "domain.h"
#include "protosw.h"
#include "socket.h"
#include "socketvar.h"
#include "errno.h"

#include "../net/if.h"
#include "../net/route.h"

#include "iso.h"
#include "iso_var.h"
#include "iso_pcb.h"
#define CLNP_ER_CODES
#include "clnp.h"
#include "clnp_stat.h"
#include "argo_debug.h"

static struct clnp_fixed er_template = {
	ISO8473_CLNP,	/* network identifier */
	0,				/* length */
	ISO8473_V1,		/* version */
	CLNP_TTL,		/* ttl */
	CLNP_ER,		/* type */
	0,				/* segment length */
	0				/* checksum */
};

/*
 * FUNCTION:		clnp_er_input
 *
 * PURPOSE:			Process an ER pdu.
 *
 * RETURNS:			
 *
 * SIDE EFFECTS:	
 *
 * NOTES:			
 */
clnp_er_input(m, src, reason)
struct mbuf		*m;		/* ptr to packet itself */
struct iso_addr	*src;	/* ptr to src of er */
u_char			reason;	/* reason code of er */
{
	int	cmd = -1;
	extern u_char clnp_protox[];

	IFDEBUG(D_CTLINPUT)
		printf("clnp_er_input: m x%x, src %s, reason x%x\n", m, 
			clnp_iso_addrp(src), reason);
	ENDDEBUG

	INCSTAT(cns_er_inhist[clnp_er_index(reason)]);
	switch (reason) {
		case GEN_NOREAS:
		case GEN_PROTOERR:
			break;
		case GEN_BADCSUM:		
			cmd = PRC_PARAMPROB;
			break;
		case GEN_CONGEST:		
			cmd = PRC_QUENCH;
			break;
		case GEN_HDRSYNTAX:		
			cmd = PRC_PARAMPROB;
			break;
		case GEN_SEGNEEDED:		
			cmd = PRC_MSGSIZE; 
			break;
		case GEN_INCOMPLETE:	
			cmd = PRC_PARAMPROB; 		
			break;
		case GEN_DUPOPT:		
			cmd = PRC_PARAMPROB;		
			break;
		case ADDR_DESTUNREACH:	
			cmd = PRC_UNREACH_HOST; 	
			break;
		case ADDR_DESTUNKNOWN:	
			cmd = PRC_UNREACH_PROTOCOL; 
			break;
		case SRCRT_UNSPECERR:
		case SRCRT_SYNTAX:
		case SRCRT_UNKNOWNADDR:
		case SRCRT_BADPATH:
			cmd = PRC_UNREACH_SRCFAIL;
			break;
		case TTL_EXPTRANSIT:	
			cmd = PRC_TIMXCEED_INTRANS;	
			break;
		case TTL_EXPREASS:		
			cmd = PRC_TIMXCEED_REASS;	
			break;
		case DISC_UNSUPPOPT:
		case DISC_UNSUPPVERS:
		case DISC_UNSUPPSECURE:
		case DISC_UNSUPPSRCRT:
		case DISC_UNSUPPRECRT:
			cmd = PRC_PARAMPROB; 
			break;
		case REASS_INTERFERE:	
			cmd = PRC_TIMXCEED_REASS;
			break;
	}

	/*
	 *	tpclnp_ctlinput1 is called directly so that we don't
	 *	have to build an iso_sockaddr out of src.
	 */
	if (cmd >= 0)
		tpclnp_ctlinput1(cmd, src);

	m_freem(m);
}

/*
 * FUNCTION:		clnp_discard
 *
 * PURPOSE:			Discard a clnp datagram
 *
 * RETURNS:			nothing
 *
 * SIDE EFFECTS:	Will emit an ER pdu if possible
 *
 * NOTES:			This code assumes that we have previously tried to pull
 *					up the header of the datagram into one mbuf.
 */
clnp_discard(m, reason)
struct mbuf	*m;		/* header of packet to discard */
char					reason;	/* reason for discard */
{
	IFDEBUG(D_DISCARD)
		printf("clnp_discard: m x%x, reason x%x\n", m, reason);
	ENDDEBUG

	if (m != NULL) {
		if (m->m_len >= sizeof(struct clnp_fixed)) {
			register struct clnp_fixed *clnp = mtod(m, struct clnp_fixed *);

			if (((clnp->cnf_type & CNF_TYPE) != CLNP_ER) &&
				(clnp->cnf_type & CNF_ERR_OK)) {
					clnp_emit_er(m, reason);
					return;
			}
		}
		m_freem(m);
	}
}

/*
 * FUNCTION:		clnp_emit_er
 *
 * PURPOSE:			Send an ER pdu.
 *					The src of the of the ER pdu is the host that is sending
 *					the ER (ie. us), *not* the original destination of the
 *					packet.
 *
 * RETURNS:			nothing
 *
 * SIDE EFFECTS:	
 *
 * NOTES:			Takes responsibility for freeing mbuf passed
 *					This function may be called with a packet that
 *					was created by us; in this case, do not send
 *					an ER.
 */
clnp_emit_er(m, reason)
struct mbuf	*m;		/* header of packet to discard */
char					reason;	/* reason for discard */
{
	register struct clnp_fixed	*clnp = mtod(m, struct clnp_fixed *);
	register struct clnp_fixed	*er;
	struct route_iso			route;
	struct ifnet				*ifp;
	struct sockaddr				*first_hop;
	struct iso_addr				src, dst, *our_addr;
	caddr_t						hoff, hend;
	int							total_len;		/* total len of dg */
	struct mbuf 				*m0;			/* contains er pdu hdr */
	struct iso_ifaddr			*ia = 0;

	IFDEBUG(D_DISCARD)
		printf("clnp_emit_er: m x%x, hdr len %d\n", m, clnp->cnf_hdr_len);
	ENDDEBUG

	bzero((caddr_t)&route, sizeof(route));

	/*
	 *	If header length is incorrect, or entire header is not contained
	 *	in this mbuf, we punt
	 */
	if ((clnp->cnf_hdr_len < CLNP_HDR_MIN) ||
		(clnp->cnf_hdr_len > CLNP_HDR_MAX) ||
		(clnp->cnf_hdr_len > m->m_len))
		goto bad;
	
	/* extract src, dest address */
	hend = (caddr_t)clnp + clnp->cnf_hdr_len;
	hoff = (caddr_t)clnp + sizeof(struct clnp_fixed);
	CLNP_EXTRACT_ADDR(dst, hoff, hend);
	if (hoff == (caddr_t)0) {
		goto bad;
	}
	CLNP_EXTRACT_ADDR(src, hoff, hend);
	if (hoff == (caddr_t)0) {
		goto bad;
	}
	
	/*
	 *	Do not send ER if we generated the packet.
	 */
	if (clnp_ours(&src))
		goto bad;

	/* 
	 *	Trim mbuf to hold only the header.
	 *	This mbuf will be the 'data' of the er pdu
	 */
	if (m->m_next != NULL) {
		m_freem(m->m_next);
		m->m_next = NULL;
	}

	if (m->m_len > clnp->cnf_hdr_len)
		m_adj(m, (int)-(m->m_len - (int)clnp->cnf_hdr_len));

	/* route er pdu: note we send pkt to src of original packet  */
	if (clnp_route(&src, &route, /* flags */0, &first_hop, &ia) != 0)
		goto bad;

	/* compute our address based upon firsthop/ifp */
	if (ia)
			our_addr = &ia->ia_addr.siso_addr;
	else
			goto bad;
	ifp = ia->ia_ifp;

	IFDEBUG(D_DISCARD)
		printf("clnp_emit_er: to %s", clnp_iso_addrp(&src));
		printf(" from %s\n", clnp_iso_addrp(our_addr));
	ENDDEBUG

	IFDEBUG(D_DISCARD)
		printf("clnp_emit_er: packet routed to %s\n", 
			clnp_iso_addrp(&((struct sockaddr_iso *)first_hop)->siso_addr));
	ENDDEBUG

	/* allocate mbuf for er pdu header: punt on no space */
	MGET(m0, M_DONTWAIT, MT_HEADER);
	if (m0 == 0)
		goto bad;
	
	m0->m_next = m;
	er = mtod(m0, struct clnp_fixed *);
	*er = er_template;

	/* setup src/dst on er pdu */
	/* NOTE REVERSAL OF SRC/DST */
	hoff = (caddr_t)er + sizeof(struct clnp_fixed);
	CLNP_INSERT_ADDR(hoff, src);
	CLNP_INSERT_ADDR(hoff, *our_addr);

	/*
	 *	TODO: if complete src rt was specified, then reverse path, and
	 *	copy into er as option.
	 */

	/* add er option */
	*hoff++ = CLNPOVAL_ERREAS;	/* code */
	*hoff++ = 2;				/* length */
	*hoff++ = reason;			/* discard reason */
	*hoff++ = 0;				/* error localization = not specified */

	/* set length */
	er->cnf_hdr_len = m0->m_len = (u_char)(hoff - (caddr_t)er);
	total_len = m0->m_len + m->m_len;
	HTOC(er->cnf_seglen_msb, er->cnf_seglen_lsb, total_len);

	/* compute checksum (on header only) */
	iso_gen_csum(m0, CLNP_CKSUM_OFF, (int)er->cnf_hdr_len);

	/* trim packet if too large for interface */
	if (total_len > ifp->if_mtu)
		m_adj(m0, -(total_len - ifp->if_mtu));
	
	/* send packet */
	INCSTAT(cns_er_outhist[clnp_er_index(reason)]);
	(void) (*ifp->if_output)(ifp, m0, first_hop, route.ro_rt);
	goto done;

bad:
	m_freem(m);

done:
	/* free route if it is a temp */
	if (route.ro_rt != NULL)
		RTFREE(route.ro_rt);
}

clnp_er_index(p)
u_char p;
{
	register u_char *cp = clnp_er_codes + CLNP_ERRORS;
	while (cp > clnp_er_codes) {
		cp--;
		if (*cp == p)
			return (cp - clnp_er_codes);
	}
	return (CLNP_ERRORS + 1);
}
Commit	Line	Data
15637ed4 RG	1	/*-
	2	* Copyright (c) 1991 The Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
	20	*
	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
	32	*
43371f85 RG	33	* from: @(#)clnp_er.c 7.7 (Berkeley) 5/6/91
43371f85 RG	34	* $Id$
15637ed4 RG	35	*/
	36
	37	/***********************************************************
	38	Copyright IBM Corporation 1987
	39
	40	All Rights Reserved
	41
	42	Permission to use, copy, modify, and distribute this software and its
	43	documentation for any purpose and without fee is hereby granted,
	44	provided that the above copyright notice appear in all copies and that
	45	both that copyright notice and this permission notice appear in
	46	supporting documentation, and that the name of IBM not be
	47	used in advertising or publicity pertaining to distribution of the
	48	software without specific, written prior permission.
	49
	50	IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
	51	ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
	52	IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
	53	ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	54	WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
	55	ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
	56	SOFTWARE.
	57
	58	******************************************************************/
	59
	60	/*
	61	* ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
	62	*/
15637ed4 RG	63
	64	#include "param.h"
	65	#include "mbuf.h"
	66	#include "domain.h"
	67	#include "protosw.h"
	68	#include "socket.h"
	69	#include "socketvar.h"
	70	#include "errno.h"
	71
	72	#include "../net/if.h"
	73	#include "../net/route.h"
	74
	75	#include "iso.h"
	76	#include "iso_var.h"
	77	#include "iso_pcb.h"
	78	#define CLNP_ER_CODES
	79	#include "clnp.h"
	80	#include "clnp_stat.h"
	81	#include "argo_debug.h"
	82
	83	static struct clnp_fixed er_template = {
	84	ISO8473_CLNP, /* network identifier */
	85	0, /* length */
	86	ISO8473_V1, /* version */
	87	CLNP_TTL, /* ttl */
	88	CLNP_ER, /* type */
	89	0, /* segment length */
	90	0 /* checksum */
	91	};
	92
	93	/*
	94	* FUNCTION: clnp_er_input
	95	*
	96	* PURPOSE: Process an ER pdu.
	97	*
	98	* RETURNS:
	99	*
	100	* SIDE EFFECTS:
	101	*
	102	* NOTES:
	103	*/
	104	clnp_er_input(m, src, reason)
	105	struct mbuf m; / ptr to packet itself */
	106	struct iso_addr src; / ptr to src of er */
	107	u_char reason; /* reason code of er */
	108	{
	109	int cmd = -1;
	110	extern u_char clnp_protox[];
	111
	112	IFDEBUG(D_CTLINPUT)
	113	printf("clnp_er_input: m x%x, src %s, reason x%x\n", m,
	114	clnp_iso_addrp(src), reason);
	115	ENDDEBUG
	116
	117	INCSTAT(cns_er_inhist[clnp_er_index(reason)]);
	118	switch (reason) {
	119	case GEN_NOREAS:
	120	case GEN_PROTOERR:
	121	break;
	122	case GEN_BADCSUM:
	123	cmd = PRC_PARAMPROB;
	124	break;
	125	case GEN_CONGEST:
	126	cmd = PRC_QUENCH;
127	break;
128	case GEN_HDRSYNTAX:
129	cmd = PRC_PARAMPROB;
130	break;
131	case GEN_SEGNEEDED:
132	cmd = PRC_MSGSIZE;
133	break;
134	case GEN_INCOMPLETE:
135	cmd = PRC_PARAMPROB;
136	break;
137	case GEN_DUPOPT:
138	cmd = PRC_PARAMPROB;
139	break;
140	case ADDR_DESTUNREACH:
141	cmd = PRC_UNREACH_HOST;
142	break;
143	case ADDR_DESTUNKNOWN:
144	cmd = PRC_UNREACH_PROTOCOL;
145	break;
146	case SRCRT_UNSPECERR:
147	case SRCRT_SYNTAX:
148	case SRCRT_UNKNOWNADDR:
149	case SRCRT_BADPATH:
150	cmd = PRC_UNREACH_SRCFAIL;
151	break;
152	case TTL_EXPTRANSIT:
153	cmd = PRC_TIMXCEED_INTRANS;
154	break;
155	case TTL_EXPREASS:
156	cmd = PRC_TIMXCEED_REASS;
157	break;
158	case DISC_UNSUPPOPT:
159	case DISC_UNSUPPVERS:
160	case DISC_UNSUPPSECURE:
161	case DISC_UNSUPPSRCRT:
162	case DISC_UNSUPPRECRT:
163	cmd = PRC_PARAMPROB;
164	break;
165	case REASS_INTERFERE:
166	cmd = PRC_TIMXCEED_REASS;
167	break;
168	}
169
170	/*
171	* tpclnp_ctlinput1 is called directly so that we don't
172	* have to build an iso_sockaddr out of src.
173	*/
174	if (cmd >= 0)
175	tpclnp_ctlinput1(cmd, src);
176
177	m_freem(m);
178	}
179
180	/*
181	* FUNCTION: clnp_discard
182	*
183	* PURPOSE: Discard a clnp datagram
184	*
185	* RETURNS: nothing
186	*
187	* SIDE EFFECTS: Will emit an ER pdu if possible
188	*
189	* NOTES: This code assumes that we have previously tried to pull
190	* up the header of the datagram into one mbuf.
191	*/
192	clnp_discard(m, reason)
193	struct mbuf m; / header of packet to discard */
194	char reason; /* reason for discard */
195	{
196	IFDEBUG(D_DISCARD)
197	printf("clnp_discard: m x%x, reason x%x\n", m, reason);
198	ENDDEBUG
199
200	if (m != NULL) {
201	if (m->m_len >= sizeof(struct clnp_fixed)) {
202	register struct clnp_fixed clnp = mtod(m, struct clnp_fixed );
203
204	if (((clnp->cnf_type & CNF_TYPE) != CLNP_ER) &&
205	(clnp->cnf_type & CNF_ERR_OK)) {
206	clnp_emit_er(m, reason);
207	return;
208	}
209	}
210	m_freem(m);
211	}
212	}
213
214	/*
215	* FUNCTION: clnp_emit_er
216	*
217	* PURPOSE: Send an ER pdu.
218	* The src of the of the ER pdu is the host that is sending
219	* the ER (ie. us), not the original destination of the
220	* packet.
221	*
222	* RETURNS: nothing
223	*
224	* SIDE EFFECTS:
225	*
226	* NOTES: Takes responsibility for freeing mbuf passed
227	* This function may be called with a packet that
228	* was created by us; in this case, do not send
229	* an ER.
230	*/
231	clnp_emit_er(m, reason)
232	struct mbuf m; / header of packet to discard */
233	char reason; /* reason for discard */
234	{
235	register struct clnp_fixed clnp = mtod(m, struct clnp_fixed );
236	register struct clnp_fixed *er;
237	struct route_iso route;
238	struct ifnet *ifp;
239	struct sockaddr *first_hop;
240	struct iso_addr src, dst, *our_addr;
241	caddr_t hoff, hend;
242	int total_len; /* total len of dg */
243	struct mbuf m0; / contains er pdu hdr */
244	struct iso_ifaddr *ia = 0;
245
246	IFDEBUG(D_DISCARD)
247	printf("clnp_emit_er: m x%x, hdr len %d\n", m, clnp->cnf_hdr_len);
248	ENDDEBUG
249
250	bzero((caddr_t)&route, sizeof(route));
251
252	/*
253	* If header length is incorrect, or entire header is not contained
254	* in this mbuf, we punt
255	*/
256	if ((clnp->cnf_hdr_len < CLNP_HDR_MIN) \|\|
257	(clnp->cnf_hdr_len > CLNP_HDR_MAX) \|\|
258	(clnp->cnf_hdr_len > m->m_len))
259	goto bad;
260
261	/* extract src, dest address */
262	hend = (caddr_t)clnp + clnp->cnf_hdr_len;
263	hoff = (caddr_t)clnp + sizeof(struct clnp_fixed);
264	CLNP_EXTRACT_ADDR(dst, hoff, hend);
265	if (hoff == (caddr_t)0) {
266	goto bad;
267	}
268	CLNP_EXTRACT_ADDR(src, hoff, hend);
269	if (hoff == (caddr_t)0) {
270	goto bad;
271	}
272
273	/*
274	* Do not send ER if we generated the packet.
275	*/
276	if (clnp_ours(&src))
277	goto bad;
278
279	/*
280	* Trim mbuf to hold only the header.
281	* This mbuf will be the 'data' of the er pdu
282	*/
283	if (m->m_next != NULL) {
284	m_freem(m->m_next);
285	m->m_next = NULL;
286	}
287
288	if (m->m_len > clnp->cnf_hdr_len)
289	m_adj(m, (int)-(m->m_len - (int)clnp->cnf_hdr_len));
290
291	/* route er pdu: note we send pkt to src of original packet */
292	if (clnp_route(&src, &route, /* flags */0, &first_hop, &ia) != 0)
293	goto bad;
294
295	/* compute our address based upon firsthop/ifp */
296	if (ia)
297	our_addr = &ia->ia_addr.siso_addr;
298	else
299	goto bad;
300	ifp = ia->ia_ifp;
301
302	IFDEBUG(D_DISCARD)
303	printf("clnp_emit_er: to %s", clnp_iso_addrp(&src));
304	printf(" from %s\n", clnp_iso_addrp(our_addr));
305	ENDDEBUG
306
307	IFDEBUG(D_DISCARD)
308	printf("clnp_emit_er: packet routed to %s\n",
309	clnp_iso_addrp(&((struct sockaddr_iso *)first_hop)->siso_addr));
310	ENDDEBUG
311
312	/* allocate mbuf for er pdu header: punt on no space */
313	MGET(m0, M_DONTWAIT, MT_HEADER);
314	if (m0 == 0)
315	goto bad;
316
317	m0->m_next = m;
318	er = mtod(m0, struct clnp_fixed *);
319	*er = er_template;
320
321	/* setup src/dst on er pdu */
322	/* NOTE REVERSAL OF SRC/DST */
323	hoff = (caddr_t)er + sizeof(struct clnp_fixed);
324	CLNP_INSERT_ADDR(hoff, src);
325	CLNP_INSERT_ADDR(hoff, *our_addr);
326
327	/*
328	* TODO: if complete src rt was specified, then reverse path, and
329	* copy into er as option.
330	*/
331
332	/* add er option */
333	hoff++ = CLNPOVAL_ERREAS; / code */
334	hoff++ = 2; / length */
335	hoff++ = reason; / discard reason */
336	hoff++ = 0; / error localization = not specified */
337
338	/* set length */
339	er->cnf_hdr_len = m0->m_len = (u_char)(hoff - (caddr_t)er);
340	total_len = m0->m_len + m->m_len;
341	HTOC(er->cnf_seglen_msb, er->cnf_seglen_lsb, total_len);
342
343	/* compute checksum (on header only) */
344	iso_gen_csum(m0, CLNP_CKSUM_OFF, (int)er->cnf_hdr_len);
345
346	/* trim packet if too large for interface */
347	if (total_len > ifp->if_mtu)
348	m_adj(m0, -(total_len - ifp->if_mtu));
349
350	/* send packet */
351	INCSTAT(cns_er_outhist[clnp_er_index(reason)]);
352	(void) (*ifp->if_output)(ifp, m0, first_hop, route.ro_rt);
353	goto done;
354
355	bad:
356	m_freem(m);
357
358	done:
359	/* free route if it is a temp */
360	if (route.ro_rt != NULL)
361	RTFREE(route.ro_rt);
362	}
363
364	clnp_er_index(p)
365	u_char p;
366	{
367	register u_char *cp = clnp_er_codes + CLNP_ERRORS;
368	while (cp > clnp_er_codes) {
369	cp--;
370	if (*cp == p)
371	return (cp - clnp_er_codes);
372	}
373	return (CLNP_ERRORS + 1);
374	}