[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.
 *
 *	@(#)clnp_er.c	7.7 (Berkeley) 5/6/91
 */

/***********************************************************
		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: /var/src/sys/netiso/RCS/clnp_er.c,v 5.1 89/02/09 16:20:18 hagens Exp $ */
/* $Source: /var/src/sys/netiso/RCS/clnp_er.c,v $ */

#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	*
	33	* @(#)clnp_er.c 7.7 (Berkeley) 5/6/91
	34	*/
	35
	36	/***********************************************************
	37	Copyright IBM Corporation 1987
	38
	39	All Rights Reserved
	40
	41	Permission to use, copy, modify, and distribute this software and its
	42	documentation for any purpose and without fee is hereby granted,
	43	provided that the above copyright notice appear in all copies and that
	44	both that copyright notice and this permission notice appear in
	45	supporting documentation, and that the name of IBM not be
	46	used in advertising or publicity pertaining to distribution of the
	47	software without specific, written prior permission.
	48
	49	IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
	50	ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
	51	IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
	52	ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	53	WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
	54	ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
	55	SOFTWARE.
	56
	57	******************************************************************/
	58
	59	/*
	60	* ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
	61	*/
	62	/* $Header: /var/src/sys/netiso/RCS/clnp_er.c,v 5.1 89/02/09 16:20:18 hagens Exp $ */
	63	/* $Source: /var/src/sys/netiso/RCS/clnp_er.c,v $ */
	64
65	#include "param.h"
66	#include "mbuf.h"
67	#include "domain.h"
68	#include "protosw.h"
69	#include "socket.h"
70	#include "socketvar.h"
71	#include "errno.h"
72
73	#include "../net/if.h"
74	#include "../net/route.h"
75
76	#include "iso.h"
77	#include "iso_var.h"
78	#include "iso_pcb.h"
79	#define CLNP_ER_CODES
80	#include "clnp.h"
81	#include "clnp_stat.h"
82	#include "argo_debug.h"
83
84	static struct clnp_fixed er_template = {
85	ISO8473_CLNP, /* network identifier */
86	0, /* length */
87	ISO8473_V1, /* version */
88	CLNP_TTL, /* ttl */
89	CLNP_ER, /* type */
90	0, /* segment length */
91	0 /* checksum */
92	};
93
94	/*
95	* FUNCTION: clnp_er_input
96	*
97	* PURPOSE: Process an ER pdu.
98	*
99	* RETURNS:
100	*
101	* SIDE EFFECTS:
102	*
103	* NOTES:
104	*/
105	clnp_er_input(m, src, reason)
106	struct mbuf m; / ptr to packet itself */
107	struct iso_addr src; / ptr to src of er */
108	u_char reason; /* reason code of er */
109	{
110	int cmd = -1;
111	extern u_char clnp_protox[];
112
113	IFDEBUG(D_CTLINPUT)
114	printf("clnp_er_input: m x%x, src %s, reason x%x\n", m,
115	clnp_iso_addrp(src), reason);
116	ENDDEBUG
117
118	INCSTAT(cns_er_inhist[clnp_er_index(reason)]);
119	switch (reason) {
120	case GEN_NOREAS:
121	case GEN_PROTOERR:
122	break;
123	case GEN_BADCSUM:
124	cmd = PRC_PARAMPROB;
125	break;
126	case GEN_CONGEST:
127	cmd = PRC_QUENCH;
128	break;
129	case GEN_HDRSYNTAX:
130	cmd = PRC_PARAMPROB;
131	break;
132	case GEN_SEGNEEDED:
133	cmd = PRC_MSGSIZE;
134	break;
135	case GEN_INCOMPLETE:
136	cmd = PRC_PARAMPROB;
137	break;
138	case GEN_DUPOPT:
139	cmd = PRC_PARAMPROB;
140	break;
141	case ADDR_DESTUNREACH:
142	cmd = PRC_UNREACH_HOST;
143	break;
144	case ADDR_DESTUNKNOWN:
145	cmd = PRC_UNREACH_PROTOCOL;
146	break;
147	case SRCRT_UNSPECERR:
148	case SRCRT_SYNTAX:
149	case SRCRT_UNKNOWNADDR:
150	case SRCRT_BADPATH:
151	cmd = PRC_UNREACH_SRCFAIL;
152	break;
153	case TTL_EXPTRANSIT:
154	cmd = PRC_TIMXCEED_INTRANS;
155	break;
156	case TTL_EXPREASS:
157	cmd = PRC_TIMXCEED_REASS;
158	break;
159	case DISC_UNSUPPOPT:
160	case DISC_UNSUPPVERS:
161	case DISC_UNSUPPSECURE:
162	case DISC_UNSUPPSRCRT:
163	case DISC_UNSUPPRECRT:
164	cmd = PRC_PARAMPROB;
165	break;
166	case REASS_INTERFERE:
167	cmd = PRC_TIMXCEED_REASS;
168	break;
169	}
170
171	/*
172	* tpclnp_ctlinput1 is called directly so that we don't
173	* have to build an iso_sockaddr out of src.
174	*/
175	if (cmd >= 0)
176	tpclnp_ctlinput1(cmd, src);
177
178	m_freem(m);
179	}
180
181	/*
182	* FUNCTION: clnp_discard
183	*
184	* PURPOSE: Discard a clnp datagram
185	*
186	* RETURNS: nothing
187	*
188	* SIDE EFFECTS: Will emit an ER pdu if possible
189	*
190	* NOTES: This code assumes that we have previously tried to pull
191	* up the header of the datagram into one mbuf.
192	*/
193	clnp_discard(m, reason)
194	struct mbuf m; / header of packet to discard */
195	char reason; /* reason for discard */
196	{
197	IFDEBUG(D_DISCARD)
198	printf("clnp_discard: m x%x, reason x%x\n", m, reason);
199	ENDDEBUG
200
201	if (m != NULL) {
202	if (m->m_len >= sizeof(struct clnp_fixed)) {
203	register struct clnp_fixed clnp = mtod(m, struct clnp_fixed );
204
205	if (((clnp->cnf_type & CNF_TYPE) != CLNP_ER) &&
206	(clnp->cnf_type & CNF_ERR_OK)) {
207	clnp_emit_er(m, reason);
208	return;
209	}
210	}
211	m_freem(m);
212	}
213	}
214
215	/*
216	* FUNCTION: clnp_emit_er
217	*
218	* PURPOSE: Send an ER pdu.
219	* The src of the of the ER pdu is the host that is sending
220	* the ER (ie. us), not the original destination of the
221	* packet.
222	*
223	* RETURNS: nothing
224	*
225	* SIDE EFFECTS:
226	*
227	* NOTES: Takes responsibility for freeing mbuf passed
228	* This function may be called with a packet that
229	* was created by us; in this case, do not send
230	* an ER.
231	*/
232	clnp_emit_er(m, reason)
233	struct mbuf m; / header of packet to discard */
234	char reason; /* reason for discard */
235	{
236	register struct clnp_fixed clnp = mtod(m, struct clnp_fixed );
237	register struct clnp_fixed *er;
238	struct route_iso route;
239	struct ifnet *ifp;
240	struct sockaddr *first_hop;
241	struct iso_addr src, dst, *our_addr;
242	caddr_t hoff, hend;
243	int total_len; /* total len of dg */
244	struct mbuf m0; / contains er pdu hdr */
245	struct iso_ifaddr *ia = 0;
246
247	IFDEBUG(D_DISCARD)
248	printf("clnp_emit_er: m x%x, hdr len %d\n", m, clnp->cnf_hdr_len);
249	ENDDEBUG
250
251	bzero((caddr_t)&route, sizeof(route));
252
253	/*
254	* If header length is incorrect, or entire header is not contained
255	* in this mbuf, we punt
256	*/
257	if ((clnp->cnf_hdr_len < CLNP_HDR_MIN) \|\|
258	(clnp->cnf_hdr_len > CLNP_HDR_MAX) \|\|
259	(clnp->cnf_hdr_len > m->m_len))
260	goto bad;
261
262	/* extract src, dest address */
263	hend = (caddr_t)clnp + clnp->cnf_hdr_len;
264	hoff = (caddr_t)clnp + sizeof(struct clnp_fixed);
265	CLNP_EXTRACT_ADDR(dst, hoff, hend);
266	if (hoff == (caddr_t)0) {
267	goto bad;
268	}
269	CLNP_EXTRACT_ADDR(src, hoff, hend);
270	if (hoff == (caddr_t)0) {
271	goto bad;
272	}
273
274	/*
275	* Do not send ER if we generated the packet.
276	*/
277	if (clnp_ours(&src))
278	goto bad;
279
280	/*
281	* Trim mbuf to hold only the header.
282	* This mbuf will be the 'data' of the er pdu
283	*/
284	if (m->m_next != NULL) {
285	m_freem(m->m_next);
286	m->m_next = NULL;
287	}
288
289	if (m->m_len > clnp->cnf_hdr_len)
290	m_adj(m, (int)-(m->m_len - (int)clnp->cnf_hdr_len));
291
292	/* route er pdu: note we send pkt to src of original packet */
293	if (clnp_route(&src, &route, /* flags */0, &first_hop, &ia) != 0)
294	goto bad;
295
296	/* compute our address based upon firsthop/ifp */
297	if (ia)
298	our_addr = &ia->ia_addr.siso_addr;
299	else
300	goto bad;
301	ifp = ia->ia_ifp;
302
303	IFDEBUG(D_DISCARD)
304	printf("clnp_emit_er: to %s", clnp_iso_addrp(&src));
305	printf(" from %s\n", clnp_iso_addrp(our_addr));
306	ENDDEBUG
307
308	IFDEBUG(D_DISCARD)
309	printf("clnp_emit_er: packet routed to %s\n",
310	clnp_iso_addrp(&((struct sockaddr_iso *)first_hop)->siso_addr));
311	ENDDEBUG
312
313	/* allocate mbuf for er pdu header: punt on no space */
314	MGET(m0, M_DONTWAIT, MT_HEADER);
315	if (m0 == 0)
316	goto bad;
317
318	m0->m_next = m;
319	er = mtod(m0, struct clnp_fixed *);
320	*er = er_template;
321
322	/* setup src/dst on er pdu */
323	/* NOTE REVERSAL OF SRC/DST */
324	hoff = (caddr_t)er + sizeof(struct clnp_fixed);
325	CLNP_INSERT_ADDR(hoff, src);
326	CLNP_INSERT_ADDR(hoff, *our_addr);
327
328	/*
329	* TODO: if complete src rt was specified, then reverse path, and
330	* copy into er as option.
331	*/
332
333	/* add er option */
334	hoff++ = CLNPOVAL_ERREAS; / code */
335	hoff++ = 2; / length */
336	hoff++ = reason; / discard reason */
337	hoff++ = 0; / error localization = not specified */
338
339	/* set length */
340	er->cnf_hdr_len = m0->m_len = (u_char)(hoff - (caddr_t)er);
341	total_len = m0->m_len + m->m_len;
342	HTOC(er->cnf_seglen_msb, er->cnf_seglen_lsb, total_len);
343
344	/* compute checksum (on header only) */
345	iso_gen_csum(m0, CLNP_CKSUM_OFF, (int)er->cnf_hdr_len);
346
347	/* trim packet if too large for interface */
348	if (total_len > ifp->if_mtu)
349	m_adj(m0, -(total_len - ifp->if_mtu));
350
351	/* send packet */
352	INCSTAT(cns_er_outhist[clnp_er_index(reason)]);
353	(void) (*ifp->if_output)(ifp, m0, first_hop, route.ro_rt);
354	goto done;
355
356	bad:
357	m_freem(m);
358
359	done:
360	/* free route if it is a temp */
361	if (route.ro_rt != NULL)
362	RTFREE(route.ro_rt);
363	}
364
365	clnp_er_index(p)
366	u_char p;
367	{
368	register u_char *cp = clnp_er_codes + CLNP_ERRORS;
369	while (cp > clnp_er_codes) {
370	cp--;
371	if (*cp == p)
372	return (cp - clnp_er_codes);
373	}
374	return (CLNP_ERRORS + 1);
375	}