[thirdparty/dhcp.git] / common / dispatch.c

/* dispatch.c

   Network input dispatcher... */

/*
 * Copyright (c) 1995, 1996, 1998, 1999 The Internet Software Consortium.
 * 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. Neither the name of The Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#ifndef lint
static char copyright[] =
"$Id: dispatch.c,v 1.53 1999/02/24 17:56:44 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"

struct protocol *protocols;
struct timeout *timeouts;
static struct timeout *free_timeouts;

int interfaces_invalidated;

#ifdef USE_POLL
/* Wait for packets to come in using poll().  When a packet comes in,
   call receive_packet to receive the packet and possibly strip hardware
   addressing information from it, and then call through the
   bootp_packet_handler hook to try to do something with it. */

void dispatch ()
{
	struct protocol *l;
	int nfds = 0;
	struct pollfd *fds;
	int count;
	int i;
	int to_msec;

	nfds = 0;
	for (l = protocols; l; l = l -> next) {
		++nfds;
	}
	fds = (struct pollfd *)malloc ((nfds) * sizeof (struct pollfd));
	if (!fds)
		log_fatal ("Can't allocate poll structures.");

	do {
		/* Call any expired timeouts, and then if there's
		   still a timeout registered, time out the select
		   call then. */
	      another:
		if (timeouts) {
			struct timeout *t;
			if (timeouts -> when <= cur_time) {
				t = timeouts;
				timeouts = timeouts -> next;
				(*(t -> func)) (t -> what);
				t -> next = free_timeouts;
				free_timeouts = t;
				goto another;
			}
			/* Figure timeout in milliseconds, and check for
			   potential overflow.   We assume that integers
			   are 32 bits, which is harmless if they're 64
			   bits - we'll just get extra timeouts in that
			   case.    Lease times would have to be quite
			   long in order for a 32-bit integer to overflow,
			   anyway. */
			to_msec = timeouts -> when - cur_time;
			if (to_msec > 2147483)
				to_msec = 2147483;
			to_msec *= 1000;
		} else
			to_msec = -1;

		/* Set up the descriptors to be polled. */
		i = 0;
		for (l = protocols; l; l = l -> next) {
			fds [i].fd = l -> fd;
			fds [i].events = POLLIN;
			fds [i].revents = 0;
			++i;
		}

		/* Wait for a packet or a timeout... XXX */
		count = poll (fds, nfds, to_msec);

		/* Get the current time... */
		GET_TIME (&cur_time);

		/* Not likely to be transitory... */
		if (count < 0) {
			if (errno == EAGAIN || errno == EINTR)
				continue;
			else
				log_fatal ("poll: %m");
		}

		i = 0;
		for (l = protocols; l; l = l -> next) {
			if ((fds [i].revents & POLLIN)) {
				fds [i].revents = 0;
				if (l -> handler)
					(*(l -> handler)) (l);
				if (interfaces_invalidated)
					break;
			}
			++i;
		}
		interfaces_invalidated = 0;
	} while (1);
}
#else
/* Wait for packets to come in using select().   When one does, call
   receive_packet to receive the packet and possibly strip hardware
   addressing information from it, and then call through the
   bootp_packet_handler hook to try to do something with it. */

void dispatch ()
{
	fd_set r, w, x;
	struct protocol *l;
	int max = 0;
	int count;
	struct timeval tv, *tvp;

	FD_ZERO (&w);
	FD_ZERO (&x);

	do {
		/* Call any expired timeouts, and then if there's
		   still a timeout registered, time out the select
		   call then. */
	      another:
		if (timeouts) {
			struct timeout *t;
			if (timeouts -> when <= cur_time) {
				t = timeouts;
				timeouts = timeouts -> next;
				(*(t -> func)) (t -> what);
				t -> next = free_timeouts;
				free_timeouts = t;
				goto another;
			}
			tv.tv_sec = timeouts -> when - cur_time;
			tv.tv_usec = 0;
			tvp = &tv;
		} else
			tvp = (struct timeval *)0;

		/* Set up the read mask. */
		FD_ZERO (&r);

		for (l = protocols; l; l = l -> next) {
			FD_SET (l -> fd, &r);
			if (l -> fd > max)
				max = l -> fd;
		}

		/* Wait for a packet or a timeout... XXX */
		count = select (max + 1, &r, &w, &x, tvp);

		/* Get the current time... */
		GET_TIME (&cur_time);

		/* Not likely to be transitory... */
		if (count < 0)
			log_fatal ("select: %m");

		for (l = protocols; l; l = l -> next) {
			if (!FD_ISSET (l -> fd, &r))
				continue;
			if (l -> handler)
				(*(l -> handler)) (l);
			if (interfaces_invalidated)
				break;
		}
		interfaces_invalidated = 0;
	} while (1);
}
#endif /* USE_POLL */

int locate_network (packet)
	struct packet *packet;
{
	struct iaddr ia;

	/* If this came through a gateway, find the corresponding subnet... */
	if (packet -> raw -> giaddr.s_addr) {
		struct subnet *subnet;
		ia.len = 4;
		memcpy (ia.iabuf, &packet -> raw -> giaddr, 4);
		subnet = find_subnet (ia);
		if (subnet)
			packet -> shared_network = subnet -> shared_network;
		else
			packet -> shared_network = (struct shared_network *)0;
	} else {
		packet -> shared_network =
			packet -> interface -> shared_network;
	}
	if (packet -> shared_network)
		return 1;
	return 0;
}

void add_timeout (when, where, what)
	TIME when;
	void (*where) PROTO ((void *));
	void *what;
{
	struct timeout *t, *q;

	/* See if this timeout supersedes an existing timeout. */
	t = (struct timeout *)0;
	for (q = timeouts; q; q = q -> next) {
		if (q -> func == where && q -> what == what) {
			if (t)
				t -> next = q -> next;
			else
				timeouts = q -> next;
			break;
		}
		t = q;
	}

	/* If we didn't supersede a timeout, allocate a timeout
	   structure now. */
	if (!q) {
		if (free_timeouts) {
			q = free_timeouts;
			free_timeouts = q -> next;
			q -> func = where;
			q -> what = what;
		} else {
			q = (struct timeout *)malloc (sizeof (struct timeout));
			if (!q)
				log_fatal ("Can't allocate timeout structure!");
			q -> func = where;
			q -> what = what;
		}
	}

	q -> when = when;

	/* Now sort this timeout into the timeout list. */

	/* Beginning of list? */
	if (!timeouts || timeouts -> when > q -> when) {
		q -> next = timeouts;
		timeouts = q;
		return;
	}

	/* Middle of list? */
	for (t = timeouts; t -> next; t = t -> next) {
		if (t -> next -> when > q -> when) {
			q -> next = t -> next;
			t -> next = q;
			return;
		}
	}

	/* End of list. */
	t -> next = q;
	q -> next = (struct timeout *)0;
}

void cancel_timeout (where, what)
	void (*where) PROTO ((void *));
	void *what;
{
	struct timeout *t, *q;

	/* Look for this timeout on the list, and unlink it if we find it. */
	t = (struct timeout *)0;
	for (q = timeouts; q; q = q -> next) {
		if (q -> func == where && q -> what == what) {
			if (t)
				t -> next = q -> next;
			else
				timeouts = q -> next;
			break;
		}
		t = q;
	}

	/* If we found the timeout, put it on the free list. */
	if (q) {
		q -> next = free_timeouts;
		free_timeouts = q;
	}
}

/* Add a protocol to the list of protocols... */
struct protocol *add_protocol (name, fd, handler, local)
	char *name;
	int fd;
	void (*handler) PROTO ((struct protocol *));
	void *local;
{
	struct protocol *p;

	p = (struct protocol *)malloc (sizeof *p);
	if (!p)
		log_fatal ("can't allocate protocol struct for %s", name);

	p -> fd = fd;
	p -> handler = handler;
	p -> local = local;

	p -> next = protocols;
	protocols = p;
	return p;
}

void remove_protocol (proto)
	struct protocol *proto;
{
	struct protocol *p, *next, *prev;

	prev = (struct protocol *)0;
	for (p = protocols; p; p = next) {
		next = p -> next;
		if (p == proto) {
			if (prev)
				prev -> next = p -> next;
			else
				protocols = p -> next;
			free (p);
		}
	}
}
Commit	Line	Data
48d507a9	1	/* dispatch.c
decf33c2	2
48d507a9	3	Network input dispatcher... */
decf33c2 TL	4
decf33c2 TL	5	/*
b25cbbad	6	* Copyright (c) 1995, 1996, 1998, 1999 The Internet Software Consortium.
decf33c2 TL	7	* All rights reserved.
	8	*
	9	* Redistribution and use in source and binary forms, with or without
	10	* modification, are permitted provided that the following conditions
	11	* are met:
	12	*
	13	* 1. Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* 2. Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer in the
	17	* documentation and/or other materials provided with the distribution.
	18	* 3. Neither the name of The Internet Software Consortium nor the names
	19	* of its contributors may be used to endorse or promote products derived
	20	* from this software without specific prior written permission.
	21	*
	22	* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
	23	* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
	24	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	25	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	26	* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
	27	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	28	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	29	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	30	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	31	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	32	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	33	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	34	* SUCH DAMAGE.
	35	*
	36	* This software has been written for the Internet Software Consortium
	37	* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
	38	* Enterprises. To learn more about the Internet Software Consortium,
	39	* see ``http://www.vix.com/isc''. To learn more about Vixie
	40	* Enterprises, see ``http://www.vix.com''.
	41	*/
	42
	43	#ifndef lint
	44	static char copyright[] =
8ae2d595	45	"$Id: dispatch.c,v 1.53 1999/02/24 17:56:44 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium. All rights reserved.\n";
decf33c2 TL	46	#endif /* not lint */
	47
	48	#include "dhcpd.h"
decf33c2	49
e4749e75	50	struct protocol *protocols;
6806c5ae TL	51	struct timeout *timeouts;
6806c5ae TL	52	static struct timeout *free_timeouts;
decf33c2	53
7d77172d	54	int interfaces_invalidated;
decf33c2	55
9c5225a5	56	#ifdef USE_POLL
b25cbbad TL	57	/* Wait for packets to come in using poll(). When a packet comes in,
	58	call receive_packet to receive the packet and possibly strip hardware
	59	addressing information from it, and then call through the
	60	bootp_packet_handler hook to try to do something with it. */
9c5225a5	61
e4749e75	62	void dispatch ()
9c5225a5	63	{
e4749e75	64	struct protocol *l;
9c5225a5 TL	65	int nfds = 0;
	66	struct pollfd *fds;
	67	int count;
	68	int i;
6806c5ae	69	int to_msec;
9c5225a5 TL	70
9c5225a5 TL	71	nfds = 0;
e4749e75	72	for (l = protocols; l; l = l -> next) {
9c5225a5 TL	73	++nfds;
9c5225a5 TL	74	}
c5568eb5	75	fds = (struct pollfd )malloc ((nfds) sizeof (struct pollfd));
9c5225a5	76	if (!fds)
8ae2d595	77	log_fatal ("Can't allocate poll structures.");
9c5225a5	78
9c5225a5	79	do {
6806c5ae TL	80	/* Call any expired timeouts, and then if there's
	81	still a timeout registered, time out the select
	82	call then. */
	83	another:
	84	if (timeouts) {
	85	struct timeout *t;
	86	if (timeouts -> when <= cur_time) {
	87	t = timeouts;
	88	timeouts = timeouts -> next;
9652af24	89	(*(t -> func)) (t -> what);
6806c5ae TL	90	t -> next = free_timeouts;
	91	free_timeouts = t;
	92	goto another;
	93	}
	94	/* Figure timeout in milliseconds, and check for
	95	potential overflow. We assume that integers
	96	are 32 bits, which is harmless if they're 64
	97	bits - we'll just get extra timeouts in that
	98	case. Lease times would have to be quite
	99	long in order for a 32-bit integer to overflow,
	100	anyway. */
	101	to_msec = timeouts -> when - cur_time;
	102	if (to_msec > 2147483)
	103	to_msec = 2147483;
	104	to_msec *= 1000;
	105	} else
	106	to_msec = -1;
	107
c3585217 TL	108	/* Set up the descriptors to be polled. */
c3585217 TL	109	i = 0;
e4749e75 TL	110	for (l = protocols; l; l = l -> next) {
e4749e75 TL	111	fds [i].fd = l -> fd;
c3585217 TL	112	fds [i].events = POLLIN;
	113	fds [i].revents = 0;
	114	++i;
	115	}
	116
9c5225a5	117	/* Wait for a packet or a timeout... XXX */
6806c5ae	118	count = poll (fds, nfds, to_msec);
9c5225a5 TL	119
	120	/* Get the current time... */
	121	GET_TIME (&cur_time);
	122
	123	/* Not likely to be transitory... */
73d0a743	124	if (count < 0) {
93ad415e	125	if (errno == EAGAIN \|\| errno == EINTR)
73d0a743 TL	126	continue;
73d0a743 TL	127	else
8ae2d595	128	log_fatal ("poll: %m");
73d0a743	129	}
9c5225a5 TL	130
9c5225a5 TL	131	i = 0;
e4749e75	132	for (l = protocols; l; l = l -> next) {
0c413cce TL	133	if ((fds [i].revents & POLLIN)) {
0c413cce TL	134	fds [i].revents = 0;
e4749e75 TL	135	if (l -> handler)
e4749e75 TL	136	(*(l -> handler)) (l);
c3585217 TL	137	if (interfaces_invalidated)
c3585217 TL	138	break;
0c413cce TL	139	}
0c413cce TL	140	++i;
9c5225a5	141	}
c3585217	142	interfaces_invalidated = 0;
9c5225a5 TL	143	} while (1);
	144	}
	145	#else
decf33c2 TL	146	/* Wait for packets to come in using select(). When one does, call
decf33c2 TL	147	receive_packet to receive the packet and possibly strip hardware
b25cbbad TL	148	addressing information from it, and then call through the
b25cbbad TL	149	bootp_packet_handler hook to try to do something with it. */
decf33c2	150
e4749e75	151	void dispatch ()
decf33c2	152	{
decf33c2	153	fd_set r, w, x;
e4749e75	154	struct protocol *l;
decf33c2 TL	155	int max = 0;
decf33c2 TL	156	int count;
6806c5ae	157	struct timeval tv, *tvp;
decf33c2	158
decf33c2 TL	159	FD_ZERO (&w);
	160	FD_ZERO (&x);
	161
	162	do {
6806c5ae TL	163	/* Call any expired timeouts, and then if there's
	164	still a timeout registered, time out the select
	165	call then. */
	166	another:
	167	if (timeouts) {
	168	struct timeout *t;
	169	if (timeouts -> when <= cur_time) {
	170	t = timeouts;
	171	timeouts = timeouts -> next;
e4749e75	172	(*(t -> func)) (t -> what);
6806c5ae TL	173	t -> next = free_timeouts;
	174	free_timeouts = t;
	175	goto another;
	176	}
	177	tv.tv_sec = timeouts -> when - cur_time;
	178	tv.tv_usec = 0;
	179	tvp = &tv;
	180	} else
	181	tvp = (struct timeval *)0;
	182
c3585217 TL	183	/* Set up the read mask. */
	184	FD_ZERO (&r);
	185
e4749e75 TL	186	for (l = protocols; l; l = l -> next) {
e4749e75 TL	187	FD_SET (l -> fd, &r);
e4749e75 TL	188	if (l -> fd > max)
e4749e75 TL	189	max = l -> fd;
c3585217	190	}
c3585217	191
decf33c2	192	/* Wait for a packet or a timeout... XXX */
6806c5ae	193	count = select (max + 1, &r, &w, &x, tvp);
decf33c2 TL	194
	195	/* Get the current time... */
	196	GET_TIME (&cur_time);
	197
	198	/* Not likely to be transitory... */
	199	if (count < 0)
8ae2d595	200	log_fatal ("select: %m");
decf33c2	201
e4749e75 TL	202	for (l = protocols; l; l = l -> next) {
e4749e75 TL	203	if (!FD_ISSET (l -> fd, &r))
decf33c2	204	continue;
e4749e75 TL	205	if (l -> handler)
e4749e75 TL	206	(*(l -> handler)) (l);
c3585217 TL	207	if (interfaces_invalidated)
c3585217 TL	208	break;
decf33c2	209	}
e7b9429f	210	interfaces_invalidated = 0;
decf33c2 TL	211	} while (1);
decf33c2 TL	212	}
9c5225a5	213	#endif /* USE_POLL */
decf33c2	214
accc7894 TL	215	int locate_network (packet)
	216	struct packet *packet;
	217	{
	218	struct iaddr ia;
	219
	220	/* If this came through a gateway, find the corresponding subnet... */
	221	if (packet -> raw -> giaddr.s_addr) {
	222	struct subnet *subnet;
	223	ia.len = 4;
	224	memcpy (ia.iabuf, &packet -> raw -> giaddr, 4);
	225	subnet = find_subnet (ia);
	226	if (subnet)
	227	packet -> shared_network = subnet -> shared_network;
	228	else
	229	packet -> shared_network = (struct shared_network *)0;
	230	} else {
	231	packet -> shared_network =
	232	packet -> interface -> shared_network;
	233	}
0c413cce TL	234	if (packet -> shared_network)
	235	return 1;
	236	return 0;
accc7894	237	}
6806c5ae TL	238
	239	void add_timeout (when, where, what)
	240	TIME when;
e4749e75 TL	241	void (where) PROTO ((void ));
e4749e75 TL	242	void *what;
6806c5ae TL	243	{
	244	struct timeout t, q;
	245
	246	/* See if this timeout supersedes an existing timeout. */
	247	t = (struct timeout *)0;
	248	for (q = timeouts; q; q = q -> next) {
e4749e75	249	if (q -> func == where && q -> what == what) {
6806c5ae TL	250	if (t)
	251	t -> next = q -> next;
	252	else
	253	timeouts = q -> next;
	254	break;
	255	}
	256	t = q;
	257	}
	258
	259	/* If we didn't supersede a timeout, allocate a timeout
	260	structure now. */
	261	if (!q) {
	262	if (free_timeouts) {
	263	q = free_timeouts;
	264	free_timeouts = q -> next;
	265	q -> func = where;
e4749e75	266	q -> what = what;
6806c5ae TL	267	} else {
	268	q = (struct timeout *)malloc (sizeof (struct timeout));
	269	if (!q)
8ae2d595	270	log_fatal ("Can't allocate timeout structure!");
6806c5ae	271	q -> func = where;
e4749e75	272	q -> what = what;
6806c5ae TL	273	}
	274	}
	275
	276	q -> when = when;
	277
	278	/* Now sort this timeout into the timeout list. */
	279
	280	/* Beginning of list? */
	281	if (!timeouts \|\| timeouts -> when > q -> when) {
	282	q -> next = timeouts;
	283	timeouts = q;
	284	return;
	285	}
	286
	287	/* Middle of list? */
	288	for (t = timeouts; t -> next; t = t -> next) {
	289	if (t -> next -> when > q -> when) {
	290	q -> next = t -> next;
	291	t -> next = q;
	292	return;
	293	}
	294	}
	295
	296	/* End of list. */
	297	t -> next = q;
	298	q -> next = (struct timeout *)0;
	299	}
	300
	301	void cancel_timeout (where, what)
e4749e75 TL	302	void (where) PROTO ((void ));
e4749e75 TL	303	void *what;
6806c5ae TL	304	{
	305	struct timeout t, q;
	306
	307	/* Look for this timeout on the list, and unlink it if we find it. */
	308	t = (struct timeout *)0;
	309	for (q = timeouts; q; q = q -> next) {
e4749e75	310	if (q -> func == where && q -> what == what) {
6806c5ae TL	311	if (t)
	312	t -> next = q -> next;
	313	else
	314	timeouts = q -> next;
	315	break;
	316	}
	317	t = q;
	318	}
	319
	320	/* If we found the timeout, put it on the free list. */
	321	if (q) {
	322	q -> next = free_timeouts;
	323	free_timeouts = q;
	324	}
	325	}
e4749e75 TL	326
e4749e75 TL	327	/* Add a protocol to the list of protocols... */
fb1989a8	328	struct protocol *add_protocol (name, fd, handler, local)
e4749e75 TL	329	char *name;
e4749e75 TL	330	int fd;
94b63c64	331	void (handler) PROTO ((struct protocol ));
e4749e75 TL	332	void *local;
	333	{
	334	struct protocol *p;
	335
	336	p = (struct protocol )malloc (sizeof p);
	337	if (!p)
8ae2d595	338	log_fatal ("can't allocate protocol struct for %s", name);
e4749e75 TL	339
	340	p -> fd = fd;
	341	p -> handler = handler;
	342	p -> local = local;
	343
	344	p -> next = protocols;
	345	protocols = p;
fb1989a8	346	return p;
e4749e75	347	}
78b8c306 TL	348
	349	void remove_protocol (proto)
	350	struct protocol *proto;
	351	{
	352	struct protocol p, next, *prev;
	353
	354	prev = (struct protocol *)0;
	355	for (p = protocols; p; p = next) {
	356	next = p -> next;
	357	if (p == proto) {
	358	if (prev)
	359	prev -> next = p -> next;
	360	else
	361	protocols = p -> next;
	362	free (p);
	363	}
	364	}
	365	}