path: root/sbin/isakmpd/exchange.c

/* $OpenBSD: exchange.c,v 1.135 2014/01/23 01:04:28 deraadt Exp $	 */
/* $EOM: exchange.c,v 1.143 2000/12/04 00:02:25 angelos Exp $	 */

/*
 * Copyright (c) 1998, 1999, 2000, 2001 Niklas Hallqvist.  All rights reserved.
 * Copyright (c) 1999, 2001 Angelos D. Keromytis.  All rights reserved.
 * Copyright (c) 1999, 2000, 2002 Håkan Olsson.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 code was written under funding by Ericsson Radio Systems.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <regex.h>
#include <keynote.h>

#include "cert.h"
#include "conf.h"
#include "connection.h"
#include "constants.h"
#include "cookie.h"
#include "crypto.h"
#include "doi.h"
#include "exchange.h"
#include "ipsec_num.h"
#include "isakmp.h"
#include "isakmp_cfg.h"
#include "libcrypto.h"
#include "log.h"
#include "message.h"
#include "timer.h"
#include "transport.h"
#include "ipsec.h"
#include "sa.h"
#include "ui.h"
#include "util.h"
#include "key.h"
#include "dpd.h"

/* Initial number of bits from the cookies used as hash.  */
#define INITIAL_BUCKET_BITS 6

/*
 * Don't try to use more bits than this as a hash.
 * We only XOR 16 bits so going above that means changing the code below
 * too.
 */
#define MAX_BUCKET_BITS 16

static void     exchange_dump(char *, struct exchange *);
static void     exchange_free_aux(void *);
static struct exchange *exchange_lookup_active(char *, int);

static
LIST_HEAD(exchange_list, exchange) *exchange_tab;

/* Works both as a maximum index and a mask.  */
static int      bucket_mask;

/*
 * Validation scripts used to test messages for correct content of
 * payloads depending on the exchange type.
 */
int16_t script_base[] = {
	ISAKMP_PAYLOAD_SA,	/* Initiator -> responder.  */
	ISAKMP_PAYLOAD_NONCE,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_SA,	/* Responder -> initiator.  */
	ISAKMP_PAYLOAD_NONCE,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_KEY_EXCH,	/* Initiator -> responder.  */
	ISAKMP_PAYLOAD_ID,
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_KEY_EXCH,	/* Responder -> initiator.  */
	ISAKMP_PAYLOAD_ID,
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_END
};

int16_t script_identity_protection[] = {
	ISAKMP_PAYLOAD_SA,	/* Initiator -> responder.  */
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_SA,	/* Responder -> initiator.  */
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_KEY_EXCH,	/* Initiator -> responder.  */
	ISAKMP_PAYLOAD_NONCE,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_KEY_EXCH,	/* Responder -> initiator.  */
	ISAKMP_PAYLOAD_NONCE,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_ID,	/* Initiator -> responder.  */
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_ID,	/* Responder -> initiator.  */
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_END
};

int16_t script_authentication_only[] = {
	ISAKMP_PAYLOAD_SA,	/* Initiator -> responder.  */
	ISAKMP_PAYLOAD_NONCE,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_SA,	/* Responder -> initiator.  */
	ISAKMP_PAYLOAD_NONCE,
	ISAKMP_PAYLOAD_ID,
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_ID,	/* Initiator -> responder.  */
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_END
};

int16_t script_aggressive[] = {
	ISAKMP_PAYLOAD_SA,	/* Initiator -> responder.  */
	ISAKMP_PAYLOAD_KEY_EXCH,
	ISAKMP_PAYLOAD_NONCE,
	ISAKMP_PAYLOAD_ID,
	EXCHANGE_SCRIPT_SWITCH,
	ISAKMP_PAYLOAD_SA,	/* Responder -> initiator.  */
	ISAKMP_PAYLOAD_KEY_EXCH,
	ISAKMP_PAYLOAD_NONCE,
	ISAKMP_PAYLOAD_ID,
	EXCHANGE_SCRIPT_AUTH,
	EXCHANGE_SCRIPT_SWITCH,
	EXCHANGE_SCRIPT_AUTH,	/* Initiator -> responder.  */
	EXCHANGE_SCRIPT_END
};

int16_t script_informational[] = {
	EXCHANGE_SCRIPT_INFO,	/* Initiator -> responder.  */
	EXCHANGE_SCRIPT_END
};

/*
 * Check what exchange SA is negotiated with and return a suitable validation
 * script.
 */
int16_t *
exchange_script(struct exchange *exchange)
{
	switch (exchange->type) {
	case ISAKMP_EXCH_BASE:
		return script_base;
	case ISAKMP_EXCH_ID_PROT:
		return script_identity_protection;
	case ISAKMP_EXCH_AUTH_ONLY:
		return script_authentication_only;
	case ISAKMP_EXCH_AGGRESSIVE:
		return script_aggressive;
	case ISAKMP_EXCH_INFO:
		return script_informational;
	case ISAKMP_EXCH_TRANSACTION:
		return script_transaction;
	default:
		if (exchange->type >= ISAKMP_EXCH_DOI_MIN)
			return exchange->doi->exchange_script(exchange->type);
	}
	return 0;
}

/*
 * Validate the message MSG's contents wrt what payloads the exchange type
 * requires at this point in the dialogue.  Return -1 if the validation fails,
 * 0 if it succeeds and the script is not finished and 1 if it's ready.
 */
static int
exchange_validate(struct message *msg)
{
	struct exchange *exchange = msg->exchange;
	int16_t		*pc = exchange->exch_pc;

	while (*pc != EXCHANGE_SCRIPT_END && *pc != EXCHANGE_SCRIPT_SWITCH) {
		LOG_DBG((LOG_EXCHANGE, 90,
		    "exchange_validate: checking for required %s",
		    *pc >= ISAKMP_PAYLOAD_NONE
		    ? constant_name(isakmp_payload_cst, *pc)
		    : constant_name(exchange_script_cst, *pc)));

		/* Check for existence of the required payloads.  */
		if ((*pc > 0 && !payload_first(msg, *pc)) ||
		    (*pc == EXCHANGE_SCRIPT_AUTH &&
		    !payload_first(msg, ISAKMP_PAYLOAD_HASH) &&
		    !payload_first(msg, ISAKMP_PAYLOAD_SIG)) ||
		    (*pc == EXCHANGE_SCRIPT_INFO &&
		    ((!payload_first(msg, ISAKMP_PAYLOAD_NOTIFY) &&
		    !payload_first(msg, ISAKMP_PAYLOAD_DELETE)) ||
		    (payload_first(msg, ISAKMP_PAYLOAD_DELETE) &&
		    !payload_first(msg, ISAKMP_PAYLOAD_HASH))))) {
			/* Missing payload.  */
			LOG_DBG((LOG_MESSAGE, 70,
			    "exchange_validate: msg %p requires missing %s",
			    msg, *pc >= ISAKMP_PAYLOAD_NONE
			    ? constant_name(isakmp_payload_cst, *pc)
			    : constant_name(exchange_script_cst, *pc)));
			return -1;
		}
		pc++;
	}
	if (*pc == EXCHANGE_SCRIPT_END)
		/* Cleanup.  */
		return 1;

	return 0;
}

/* Feed unhandled payloads to the DOI for handling. Help for exchange_run(). */
static void
exchange_handle_leftover_payloads(struct message *msg)
{
	struct exchange *exchange = msg->exchange;
	struct doi	*doi = exchange->doi;
	struct payload	*p;
	int	i;

	for (i = ISAKMP_PAYLOAD_SA; i < ISAKMP_PAYLOAD_MAX; i++) {
		if (i == ISAKMP_PAYLOAD_PROPOSAL ||
		    i == ISAKMP_PAYLOAD_TRANSFORM)
			continue;
		TAILQ_FOREACH(p, &msg->payload[i], link) {
			if (p->flags & PL_MARK)
				continue;
			if (!doi->handle_leftover_payload ||
			    doi->handle_leftover_payload(msg, i, p))
				LOG_DBG((LOG_EXCHANGE, 10,
				    "exchange_handle_leftover_payloads: "
				    "unexpected payload %s",
				    constant_name(isakmp_payload_cst, i)));
		}
	}
}

/*
 * Run the exchange script from a point given by the "program counter"
 * upto either the script's end or a transmittal of a message.  If we are
 * at the point of a reception of a message, that message should be handed
 * in here in the MSG argument.  Otherwise we are the initiator and should
 * expect MSG to be a half-cooked message without payloads.
 */
void
exchange_run(struct message *msg)
{
	struct exchange *exchange = msg->exchange;
	struct doi	*doi = exchange->doi;
	int             (*handler)(struct message *) = exchange->initiator ?
			    doi->initiator : doi->responder;
	int              done = 0;

	while (!done) {
		/*
		 * It's our turn if we're either the initiator on an even step,
		 * or the responder on an odd step of the dialogue.
		 */
		if (exchange->initiator ^ (exchange->step % 2)) {
			done = 1;
			if (exchange->step)
				msg = message_alloc_reply(msg);
			message_setup_header(msg, exchange->type, 0,
			    exchange->message_id);
			if (handler(msg)) {
				/*
				 * This can happen when transient starvation
				 * of memory occurs.
				 * XXX The peer's retransmit ought to
				 * kick-start this exchange again.  If he's
				 * stopped retransmitting he's likely dropped
				 * the SA at his side so we need to do that
				 * too, i.e.  implement automatic SA teardown
				 * after a certain amount of inactivity.
				 */
				log_print("exchange_run: doi->%s (%p) failed",
				    exchange->initiator ? "initiator" :
				    "responder", msg);
				message_free(msg);
				return;
			}
			switch (exchange_validate(msg)) {
			case 1:
				/*
				 * The last message of a multi-message
				 * exchange should not be retransmitted other
				 * than "on-demand", i.e. if we see
				 * retransmits of the last message of the peer
				 * later.
				 */
				msg->flags |= MSG_LAST;
				if (exchange->step > 0) {
					if (exchange->last_sent)
						message_free(exchange->last_sent);
					exchange->last_sent = msg;
				}
				/*
				 * After we physically have sent our last
				 * message we need to do SA-specific
				 * finalization, like telling our application
				 * the SA is ready to be used, or issuing a
				 * CONNECTED notify if we set the COMMIT bit.
				 */
				message_register_post_send(msg,
				    exchange_finalize);

				/* FALLTHROUGH */

			case 0:
				/* XXX error handling.  */
				message_send(msg);
				break;

			default:
				log_print("exchange_run: exchange_validate "
				    "failed, DOI error");
				exchange_free(exchange);
				message_free(msg);
				return;
			}
		} else {
			done = exchange_validate(msg);
			switch (done) {
			case 0:
			case 1:
				/* Feed the message to the DOI.  */
				if (handler(msg)) {
					/*
					 * Trust the peer to retransmit.
					 * XXX We have to implement SA aging
					 * with automatic teardown.
					 */
					message_free(msg);
					return;
				}
				/*
				 * Go over the yet unhandled payloads and feed
				 * them to DOI for handling.
				 */
				exchange_handle_leftover_payloads(msg);

				/*
				 * We have advanced the state.  If we have
				 * been processing an incoming message, record
				 * that message as the one to do duplication
				 * tests against.
				 */
				if (exchange->last_received)
					message_free(exchange->last_received);
				exchange->last_received = msg;
				if (exchange->flags & EXCHANGE_FLAG_ENCRYPT)
					crypto_update_iv(exchange->keystate);

				if (done) {
					exchange_finalize(msg);
					return;
				}
				break;

			case -1:
				log_print("exchange_run: exchange_validate "
				    "failed");
				/*
				 * XXX Is this the best error notification
				 * type?
				 */
				message_drop(msg,
				    ISAKMP_NOTIFY_PAYLOAD_MALFORMED, 0, 1, 1);
				return;
			}
		}

		LOG_DBG((LOG_EXCHANGE, 40,
		    "exchange_run: exchange %p finished step %d, advancing...",
		    exchange, exchange->step));
		exchange->step++;
		while (*exchange->exch_pc != EXCHANGE_SCRIPT_SWITCH &&
		    *exchange->exch_pc != EXCHANGE_SCRIPT_END)
			exchange->exch_pc++;
		exchange->exch_pc++;
	}
}

void
exchange_init(void)
{
	int	i;

	bucket_mask = (1 << INITIAL_BUCKET_BITS) - 1;
	exchange_tab = calloc(bucket_mask + 1, sizeof(struct exchange_list));
	if (!exchange_tab)
		log_fatal("exchange_init: out of memory");
	for (i = 0; i <= bucket_mask; i++)
		LIST_INIT(&exchange_tab[i]);
}

/* Lookup a phase 1 exchange out of just the initiator cookie.  */
struct exchange *
exchange_lookup_from_icookie(u_int8_t *cookie)
{
	struct exchange *exchange;
	int	i;

	for (i = 0; i <= bucket_mask; i++)
		for (exchange = LIST_FIRST(&exchange_tab[i]); exchange;
		    exchange = LIST_NEXT(exchange, link))
			if (memcmp(exchange->cookies, cookie,
			    ISAKMP_HDR_ICOOKIE_LEN) == 0 &&
			    exchange->phase == 1)
				return exchange;
	return 0;
}

/* Lookup an exchange out of the name and phase.  */
struct exchange *
exchange_lookup_by_name(char *name, int phase)
{
	struct exchange *exchange;
	int	i;

	/* If we search for nothing, we will find nothing.  */
	if (!name)
		return 0;

	for (i = 0; i <= bucket_mask; i++)
		for (exchange = LIST_FIRST(&exchange_tab[i]); exchange;
		    exchange = LIST_NEXT(exchange, link)) {
			LOG_DBG((LOG_EXCHANGE, 90,
			    "exchange_lookup_by_name: %s == %s && %d == %d?",
			    name, exchange->name ? exchange->name :
			    "<unnamed>", phase, exchange->phase));

			/*
			 * Match by name, but don't select finished exchanges,
			 * i.e where MSG_LAST are set in last_sent msg.
			 */
			if (exchange->name &&
			    strcasecmp(exchange->name, name) == 0 &&
			    exchange->phase == phase &&
			    (!exchange->last_sent ||
				(exchange->last_sent->flags & MSG_LAST) == 0))
				return exchange;
		}
	return 0;
}

/* Lookup an exchange out of the name, phase and step > 1.  */
static struct exchange *
exchange_lookup_active(char *name, int phase)
{
	struct exchange *exchange;
	int	i;

	/* XXX Almost identical to exchange_lookup_by_name.  */

	if (!name)
		return 0;

	for (i = 0; i <= bucket_mask; i++)
		for (exchange = LIST_FIRST(&exchange_tab[i]); exchange;
		    exchange = LIST_NEXT(exchange, link)) {
			LOG_DBG((LOG_EXCHANGE, 90,
			    "exchange_lookup_active: %s == %s && %d == %d?",
			    name, exchange->name ? exchange->name :
			    "<unnamed>", phase, exchange->phase));
			if (exchange->name &&
			    strcasecmp(exchange->name, name) == 0 &&
			    exchange->phase == phase) {
				if (exchange->step > 1)
					return exchange;
				else
					LOG_DBG((LOG_EXCHANGE, 80,
					    "exchange_lookup_active: avoided "
					    "early (pre-step 1) exchange %p",
					    exchange));
			}
		}
	return 0;
}

static void
exchange_enter(struct exchange *exchange)
{
	u_int16_t	bucket = 0;
	u_int8_t       *cp;
	int             i;

	/* XXX We might resize if we are crossing a certain threshold */

	for (i = 0; i < ISAKMP_HDR_COOKIES_LEN; i += 2) {
		cp = exchange->cookies + i;
		/* Doing it this way avoids alignment problems.  */
		bucket ^= cp[0] | cp[1] << 8;
	}
	for (i = 0; i < ISAKMP_HDR_MESSAGE_ID_LEN; i += 2) {
		cp = exchange->message_id + i;
		/* Doing it this way avoids alignment problems.  */
		bucket ^= cp[0] | cp[1] << 8;
	}
	bucket &= bucket_mask;
	LIST_INSERT_HEAD(&exchange_tab[bucket], exchange, link);
}

/*
 * Lookup the exchange given by the header fields MSG.  PHASE2 is false when
 * looking for phase 1 exchanges and true otherwise.
 */
struct exchange *
exchange_lookup(u_int8_t *msg, int phase2)
{
	struct exchange *exchange;
	u_int16_t       bucket = 0;
	u_int8_t       *cp;
	int             i;

	/*
         * We use the cookies to get bits to use as an index into exchange_tab,
	 * as at least one (our cookie) is a good hash, xoring all the bits,
	 * 16 at a time, and then masking, should do.  Doing it this way means
	 * we can validate cookies very fast thus delimiting the effects of
	 * "Denial of service"-attacks using packet flooding.
         */
	for (i = 0; i < ISAKMP_HDR_COOKIES_LEN; i += 2) {
		cp = msg + ISAKMP_HDR_COOKIES_OFF + i;
		/* Doing it this way avoids alignment problems.  */
		bucket ^= cp[0] | cp[1] << 8;
	}
	if (phase2)
		for (i = 0; i < ISAKMP_HDR_MESSAGE_ID_LEN; i += 2) {
			cp = msg + ISAKMP_HDR_MESSAGE_ID_OFF + i;
			/* Doing it this way avoids alignment problems.  */
			bucket ^= cp[0] | cp[1] << 8;
		}
	bucket &= bucket_mask;
	for (exchange = LIST_FIRST(&exchange_tab[bucket]);
	    exchange && (memcmp(msg + ISAKMP_HDR_COOKIES_OFF,
		exchange->cookies, ISAKMP_HDR_COOKIES_LEN) != 0 ||
		(phase2 && memcmp(msg + ISAKMP_HDR_MESSAGE_ID_OFF,
		    exchange->message_id, ISAKMP_HDR_MESSAGE_ID_LEN) != 0) ||
		(!phase2 && !zero_test(msg + ISAKMP_HDR_MESSAGE_ID_OFF,
		    ISAKMP_HDR_MESSAGE_ID_LEN)));
	    exchange = LIST_NEXT(exchange, link))
		;

	return exchange;
}

/*
 * Create a phase PHASE exchange where INITIATOR denotes our role.  DOI
 * is the domain of interpretation identifier and TYPE tells what exchange
 * type to use per either the DOI document or the ISAKMP spec proper.
 * NSA tells how many SAs we should pre-allocate, and should be zero
 * when we have the responder role.
 */
static struct exchange *
exchange_create(int phase, int initiator, int doi, int type)
{
	struct exchange *exchange;
	struct timeval	 expiration;
	int	delta;

	/*
         * We want the exchange zeroed for exchange_free to be able to find
         * out what fields have been filled-in.
         */
	exchange = calloc(1, sizeof *exchange);
	if (!exchange) {
		log_error("exchange_create: calloc (1, %lu) failed",
		    (unsigned long)sizeof *exchange);
		return 0;
	}
	exchange->phase = phase;
	exchange->step = 0;
	exchange->initiator = initiator;
	bzero(exchange->cookies, ISAKMP_HDR_COOKIES_LEN);
	bzero(exchange->message_id, ISAKMP_HDR_MESSAGE_ID_LEN);
	exchange->doi = doi_lookup(doi);
	exchange->type = type;
	exchange->policy_id = -1;
	exchange->exch_pc = exchange_script(exchange);
	exchange->last_sent = exchange->last_received = 0;
	TAILQ_INIT(&exchange->sa_list);
	TAILQ_INIT(&exchange->aca_list);

	/* Allocate the DOI-specific structure and initialize it to zeroes.  */
	if (exchange->doi->exchange_size) {
		exchange->data = calloc(1, exchange->doi->exchange_size);
		if (!exchange->data) {
			log_error("exchange_create: calloc (1, %lu) failed",
			    (unsigned long)exchange->doi->exchange_size);
			exchange_free(exchange);
			return 0;
		}
	}
	gettimeofday(&expiration, 0);
	delta = conf_get_num("General", "Exchange-max-time",
	    EXCHANGE_MAX_TIME);
	expiration.tv_sec += delta;
	exchange->death = timer_add_event("exchange_free_aux",
	    exchange_free_aux, exchange, &expiration);
	if (!exchange->death) {
		/* If we don't give up we might start leaking...  */
		exchange_free_aux(exchange);
		return 0;
	}
	return exchange;
}

struct exchange_finalization_node {
	void	(*first)(struct exchange *, void *, int);
	void	*first_arg;
	void	(*second)(struct exchange *, void *, int);
	void	*second_arg;
};

/* Run the finalization functions of ARG.  */
static void
exchange_run_finalizations(struct exchange *exchange, void *arg, int fail)
{
	struct exchange_finalization_node *node = arg;

	node->first(exchange, node->first_arg, fail);
	node->second(exchange, node->second_arg, fail);
	free(node);
}

/*
 * Add a finalization function FINALIZE with argument ARG to the tail
 * of the finalization function list of EXCHANGE.
 */
static void
exchange_add_finalization(struct exchange *exchange,
    void (*finalize)(struct exchange *, void *, int), void *arg)
{
	struct exchange_finalization_node *node;

	if (!finalize)
		return;

	if (!exchange->finalize) {
		exchange->finalize = finalize;
		exchange->finalize_arg = arg;
		return;
	}
	node = malloc(sizeof *node);
	if (!node) {
		log_error("exchange_add_finalization: malloc (%lu) failed",
		    (unsigned long)sizeof *node);
		free(arg);
		return;
	}
	node->first = exchange->finalize;
	node->first_arg = exchange->finalize_arg;
	node->second = finalize;
	node->second_arg = arg;
	exchange->finalize = exchange_run_finalizations;
	exchange->finalize_arg = node;
}

static void
exchange_establish_transaction(struct exchange *exchange, void *arg, int fail)
{
	/* Establish a TRANSACTION exchange.  */
	struct exchange_finalization_node *node =
	    (struct exchange_finalization_node *)arg;
	struct sa *isakmp_sa = sa_lookup_by_name((char *) node->second_arg, 1);

	if (isakmp_sa && !fail)
		exchange_establish_p2(isakmp_sa, ISAKMP_EXCH_TRANSACTION, 0, 0,
		    node->first, node->first_arg);

	free(node);
}

/* Establish a phase 1 exchange.  */
void
exchange_establish_p1(struct transport *t, u_int8_t type, u_int32_t doi,
    char *name, void *args, void (*finalize)(struct exchange *, void *, int),
    void *arg, int stayalive)
{
	struct exchange		*exchange;
	struct message		*msg;
	struct conf_list	*flags;
	struct conf_list_node	*flag;
	char	*tag = 0;
	char	*str;

	if (name) {
		/* If no exchange type given, fetch from the configuration.  */
		if (type == 0) {
			/*
			 * XXX Similar code can be found in
			 * exchange_setup_p1.  Share?
			 */

			/* Find out our phase 1 mode.  */
			tag = conf_get_str(name, "Configuration");
			if (!tag) {
				/* Use default setting.  */
				tag = CONF_DFLT_TAG_PHASE1_CONFIG;
			}
			/* Figure out the DOI.  XXX Factor out?  */
			str = conf_get_str(tag, "DOI");
			if (!str || strcasecmp(str, "IPSEC") == 0)
				doi = IPSEC_DOI_IPSEC;
			else if (strcasecmp(str, "ISAKMP") == 0)
				doi = ISAKMP_DOI_ISAKMP;
			else {
				log_print("exchange_establish_p1: "
				    "DOI \"%s\" unsupported", str);
				return;
			}

			/* What exchange type do we want?  */
			str = conf_get_str(tag, "EXCHANGE_TYPE");
			if (!str) {
				log_print("exchange_establish_p1: "
				    "no \"EXCHANGE_TYPE\" tag in [%s] section",
				    tag);
				return;
			}
			type = constant_value(isakmp_exch_cst, str);
			if (!type) {
				log_print("exchange_establish_p1: "
				    "unknown exchange type %s", str);
				return;
			}
		}
	}
	exchange = exchange_create(1, 1, doi, type);
	if (!exchange) {
		/* XXX Do something here?  */
		return;
	}
	if (name) {
		exchange->name = strdup(name);
		if (!exchange->name) {
			log_error("exchange_establish_p1: "
			    "strdup (\"%s\") failed", name);
			exchange_free(exchange);
			return;
		}
	}
	exchange->policy = name ? conf_get_str(name, "Configuration") : 0;
	if (!exchange->policy && name)
		exchange->policy = CONF_DFLT_TAG_PHASE1_CONFIG;

	if (name && (flags = conf_get_list(name, "Flags")) != NULL) {
		for (flag = TAILQ_FIRST(&flags->fields); flag;
		    flag = TAILQ_NEXT(flag, link))
			if (strcasecmp(flag->field, "ikecfg") == 0) {
				struct exchange_finalization_node *node;

				node = calloc(1, (unsigned long)sizeof *node);
				if (!node) {
					log_print("exchange_establish_p1: "
					    "calloc (1, %lu) failed",
					    (unsigned long)sizeof(*node));
					exchange_free(exchange);
					return;
				}
				/*
				 * Insert this finalization inbetween
				 * the original.
				 */
				node->first = finalize;
				node->first_arg = arg;
				node->second_arg = name;
				exchange_add_finalization(exchange,
				    exchange_establish_transaction,
				    node);
				finalize = 0;
			}
		conf_free_list(flags);
	}

	exchange_add_finalization(exchange, finalize, arg);
	cookie_gen(t, exchange, exchange->cookies, ISAKMP_HDR_ICOOKIE_LEN);
	exchange_enter(exchange);
	exchange_dump("exchange_establish_p1", exchange);

	msg = message_alloc(t, 0, ISAKMP_HDR_SZ);
	if (!msg) {
		log_print("exchange_establish_p1: message_alloc () failed");
		exchange_free(exchange);
		return;
	}
	msg->exchange = exchange;

	/* Do not create SA for an information or transaction exchange. */
	if (exchange->type != ISAKMP_EXCH_INFO &&
	    exchange->type != ISAKMP_EXCH_TRANSACTION) {
		/*
		 * Don't install a transport into this SA as it will be an
		 * INADDR_ANY address in the local end, which is not good at
		 * all.  Let the reply packet install the transport instead.
		 */
		sa_create(exchange, 0);
		msg->isakmp_sa = TAILQ_FIRST(&exchange->sa_list);
		if (!msg->isakmp_sa) {
			/* XXX Do something more here?  */
			message_free(msg);
			exchange_free(exchange);
			return;
		}
		sa_reference(msg->isakmp_sa);

		if (stayalive)
			msg->isakmp_sa->flags |= SA_FLAG_STAYALIVE;
	}
	msg->extra = args;

	exchange_run(msg);
}

/* Establish a phase 2 exchange.  XXX With just one SA for now.  */
void
exchange_establish_p2(struct sa *isakmp_sa, u_int8_t type, char *name,
    void *args, void (*finalize)(struct exchange *, void *, int), void *arg)
{
	struct exchange *exchange;
	struct message	*msg;
	u_int32_t        doi = ISAKMP_DOI_ISAKMP;
	u_int32_t        seq = 0;
	int              i;
	char		*tag, *str;

	if (isakmp_sa)
		doi = isakmp_sa->doi->id;

	if (name) {
		/* Find out our phase 2 modes.  */
		tag = conf_get_str(name, "Configuration");
		if (!tag) {
			log_print("exchange_establish_p2: "
			    "no configuration for peer \"%s\"", name);
			return;
		}
		seq = (u_int32_t)conf_get_num(name, "Acquire-ID", 0);

		/* Figure out the DOI.  */
		str = conf_get_str(tag, "DOI");
		if (!str || strcasecmp(str, "IPSEC") == 0)
			doi = IPSEC_DOI_IPSEC;
		else if (strcasecmp(str, "ISAKMP") == 0)
			doi = ISAKMP_DOI_ISAKMP;
		else {
			log_print("exchange_establish_p2: "
			    "DOI \"%s\" unsupported", str);
			return;
		}

		/* What exchange type do we want?  */
		if (!type) {
			str = conf_get_str(tag, "EXCHANGE_TYPE");
			if (!str) {
				log_print("exchange_establish_p2: "
				    "no \"EXCHANGE_TYPE\" tag in [%s] section",
				    tag);
				return;
			}
			/* XXX IKE dependent.  */
			type = constant_value(ike_exch_cst, str);
			if (!type) {
				log_print("exchange_establish_p2: unknown "
				    "exchange type %s", str);
				return;
			}
		}
	}
	exchange = exchange_create(2, 1, doi, type);
	if (!exchange) {
		/* XXX Do something here?  */
		return;
	}
	if (name) {
		exchange->name = strdup(name);
		if (!exchange->name) {
			log_error("exchange_establish_p2: "
			    "strdup (\"%s\") failed", name);
			exchange_free(exchange);
			return;
		}
	}
	exchange->policy = name ? conf_get_str(name, "Configuration") : 0;
	exchange->finalize = finalize;
	exchange->finalize_arg = arg;
	exchange->seq = seq;
	memcpy(exchange->cookies, isakmp_sa->cookies, ISAKMP_HDR_COOKIES_LEN);
	arc4random_buf(exchange->message_id, ISAKMP_HDR_MESSAGE_ID_LEN);
	exchange->flags |= EXCHANGE_FLAG_ENCRYPT;
	if (isakmp_sa->flags & SA_FLAG_NAT_T_ENABLE)
		exchange->flags |= EXCHANGE_FLAG_NAT_T_ENABLE;
	if (isakmp_sa->flags & SA_FLAG_NAT_T_KEEPALIVE)
		exchange->flags |= EXCHANGE_FLAG_NAT_T_KEEPALIVE;
	exchange_enter(exchange);
	exchange_dump("exchange_establish_p2", exchange);

	/*
         * Do not create SA's for informational exchanges.
         * XXX How to handle new group mode?
         */
	if (exchange->type != ISAKMP_EXCH_INFO &&
	    exchange->type != ISAKMP_EXCH_TRANSACTION) {
		/* XXX Number of SAs should come from the args structure.  */
		for (i = 0; i < 1; i++)
			if (sa_create(exchange, isakmp_sa->transport)) {
				exchange_free(exchange);
				return;
			}
	}
	msg = message_alloc(isakmp_sa->transport, 0, ISAKMP_HDR_SZ);
	msg->isakmp_sa = isakmp_sa;
	sa_reference(isakmp_sa);

	msg->extra = args;

	/* This needs to be done late or else get_keystate won't work right. */
	msg->exchange = exchange;

	exchange_run(msg);
}

/* Out of an incoming phase 1 message, setup an exchange.  */
struct exchange *
exchange_setup_p1(struct message *msg, u_int32_t doi)
{
	struct transport	*t = msg->transport;
	struct exchange		*exchange;
	struct sockaddr		*dst;
	struct conf_list	*flags;
	struct conf_list_node	*flag;
	char		*name = 0, *policy = 0, *str;
	u_int32_t        want_doi;
	u_int8_t         type;

	/* XXX Similar code can be found in exchange_establish_p1.  Share?  */

	/*
	 * Unless this is an informational exchange, look up our policy for
	 * this peer.
         */
	type = GET_ISAKMP_HDR_EXCH_TYPE(msg->iov[0].iov_base);
	if (type != ISAKMP_EXCH_INFO) {
		/*
		 * Find out our inbound phase 1 mode.
		 */
		t->vtbl->get_dst(t, &dst);
		if (sockaddr2text(dst, &str, 0) == -1)
			return 0;
		name = conf_get_str("Phase 1", str);
		free(str);
		if (name) {
			/*
			 * If another phase 1 exchange is ongoing don't bother
			 * returning the call. However, we will need to
			 * continue responding if our phase 1 exchange is
			 * still waiting for step 1 (i.e still half-open).
			 */
			if (exchange_lookup_active(name, 1))
				return 0;
		} else {
			name = conf_get_str("Phase 1", "Default");
			if (!name) {
				log_print("exchange_setup_p1: no \"Default\" "
				    "tag in [Phase 1] section");
				return 0;
			}
		}

		policy = conf_get_str(name, "Configuration");
		if (!policy)
			policy = CONF_DFLT_TAG_PHASE1_CONFIG;

		/* Figure out the DOI.  */
		str = conf_get_str(policy, "DOI");
		if (!str || strcasecmp(str, "IPSEC") == 0) {
			want_doi = IPSEC_DOI_IPSEC;
			str = "IPSEC";
		}
		else if (strcasecmp(str, "ISAKMP") == 0)
			want_doi = ISAKMP_DOI_ISAKMP;
		else {
			log_print("exchange_setup_p1: "
			    "DOI \"%s\" unsupported", str);
			return 0;
		}
		if (want_doi != doi) {
			/* XXX Should I tell what DOI I got?  */
			log_print("exchange_setup_p1: expected %s DOI", str);
			return 0;
		}
		/* What exchange type do we want?  */
		str = conf_get_str(policy, "EXCHANGE_TYPE");
		if (!str) {
			log_print("exchange_setup_p1: no \"EXCHANGE_TYPE\" "
			    "tag in [%s] section", policy);
			return 0;
		}
		type = constant_value(isakmp_exch_cst, str);
		if (!type) {
			log_print("exchange_setup_p1: "
			    "unknown exchange type %s", str);
			return 0;
		}
		if (type != GET_ISAKMP_HDR_EXCH_TYPE(msg->iov[0].iov_base)) {
			log_print("exchange_setup_p1: "
			    "expected exchange type %s got %s", str,
			    constant_name(isakmp_exch_cst,
				GET_ISAKMP_HDR_EXCH_TYPE(msg->iov[0].iov_base)));
			return 0;
		}
	}
	exchange = exchange_create(1, 0, doi, type);
	if (!exchange)
		return 0;

	exchange->name = name ? strdup(name) : 0;
	if (name && !exchange->name) {
		log_error("exchange_setup_p1: strdup (\"%s\") failed", name);
		exchange_free(exchange);
		return 0;
	}
	exchange->policy = policy;

	if (name && (flags = conf_get_list(name, "Flags")) != NULL) {
		for (flag = TAILQ_FIRST(&flags->fields); flag;
		    flag = TAILQ_NEXT(flag, link))
			if (strcasecmp(flag->field, "ikecfg") == 0) {
				struct exchange_finalization_node *node;

				node = calloc(1, (unsigned long)sizeof *node);
				if (!node) {
					log_print("exchange_establish_p1: "
					    "calloc (1, %lu) failed",
					    (unsigned long)sizeof(*node));
					exchange_free(exchange);
					return 0;
				}
				/*
				 * Insert this finalization inbetween
				 * the original.
				 */
				node->first = 0;
				node->first_arg = 0;
				node->second_arg = name;
				exchange_add_finalization(exchange,
				    exchange_establish_transaction,
				    node);
			}
		conf_free_list(flags);
	}

	cookie_gen(msg->transport, exchange, exchange->cookies +
	    ISAKMP_HDR_ICOOKIE_LEN, ISAKMP_HDR_RCOOKIE_LEN);
	GET_ISAKMP_HDR_ICOOKIE(msg->iov[0].iov_base, exchange->cookies);
	exchange_enter(exchange);
	exchange_dump("exchange_setup_p1", exchange);
	return exchange;
}

/* Out of an incoming phase 2 message, setup an exchange.  */
struct exchange *
exchange_setup_p2(struct message *msg, u_int8_t doi)
{
	struct exchange *exchange;
	u_int8_t	*buf = msg->iov[0].iov_base;

	exchange = exchange_create(2, 0, doi, GET_ISAKMP_HDR_EXCH_TYPE(buf));
	if (!exchange)
		return 0;
	GET_ISAKMP_HDR_ICOOKIE(buf, exchange->cookies);
	GET_ISAKMP_HDR_RCOOKIE(buf,
	    exchange->cookies + ISAKMP_HDR_ICOOKIE_LEN);
	GET_ISAKMP_HDR_MESSAGE_ID(buf, exchange->message_id);
	if (msg->isakmp_sa && (msg->isakmp_sa->flags & SA_FLAG_NAT_T_ENABLE))
		exchange->flags |= EXCHANGE_FLAG_NAT_T_ENABLE;
	if (msg->isakmp_sa && (msg->isakmp_sa->flags & SA_FLAG_NAT_T_KEEPALIVE))
		exchange->flags |= EXCHANGE_FLAG_NAT_T_KEEPALIVE;
	exchange_enter(exchange);
	exchange_dump("exchange_setup_p2", exchange);
	return exchange;
}

/* Dump interesting data about an exchange.  */
static void
exchange_dump_real(char *header, struct exchange *exchange, int class,
    int level)
{
	struct sa	*sa;
	char             buf[LOG_SIZE];
	/* Don't risk overflowing the final log buffer.  */
	size_t           bufsize_max = LOG_SIZE - strlen(header) - 32;

	LOG_DBG((class, level,
	    "%s: %p %s %s policy %s phase %d doi %d exchange %d step %d",
	    header, exchange, exchange->name ? exchange->name : "<unnamed>",
	    exchange->policy ? exchange->policy : "<no policy>",
	    exchange->initiator ? "initiator" : "responder", exchange->phase,
	    exchange->doi->id, exchange->type, exchange->step));
	LOG_DBG((class, level, "%s: icookie %08x%08x rcookie %08x%08x", header,
	    decode_32(exchange->cookies), decode_32(exchange->cookies + 4),
	    decode_32(exchange->cookies + 8),
	    decode_32(exchange->cookies + 12)));

	/* Include phase 2 SA list for this exchange */
	if (exchange->phase == 2) {
		snprintf(buf, bufsize_max, "sa_list ");
		for (sa = TAILQ_FIRST(&exchange->sa_list);
		    sa && strlen(buf) < bufsize_max; sa = TAILQ_NEXT(sa, next))
			snprintf(buf + strlen(buf), bufsize_max - strlen(buf),
			    "%p ", sa);
		if (sa)
			strlcat(buf, "...", bufsize_max);
	} else
		buf[0] = '\0';

	LOG_DBG((class, level, "%s: msgid %08x %s", header,
	    decode_32(exchange->message_id), buf));
}

static void
exchange_dump(char *header, struct exchange *exchange)
{
	exchange_dump_real(header, exchange, LOG_EXCHANGE, 10);
}

void
exchange_report(void)
{
	struct exchange	*exchange;
	int	i;

	for (i = 0; i <= bucket_mask; i++)
		for (exchange = LIST_FIRST(&exchange_tab[i]); exchange;
		    exchange = LIST_NEXT(exchange, link))
			exchange_dump_real("exchange_report", exchange,
			    LOG_REPORT, 0);
}

/*
 * Release all resources this exchange is using *except* for the "death"
 * event.  When removing an exchange from the expiration handler that event
 * will be dealt with therein instead.
 */
static void
exchange_free_aux(void *v_exch)
{
	struct exchange		*exchange = v_exch;
	struct sa		*sa, *next_sa;
	struct cert_handler	*handler;

	LOG_DBG((LOG_EXCHANGE, 80, "exchange_free_aux: freeing exchange %p",
	    exchange));

	if (exchange->last_received)
		message_free(exchange->last_received);
	if (exchange->last_sent)
		message_free(exchange->last_sent);
	if (exchange->in_transit &&
	    exchange->in_transit != exchange->last_sent)
		message_free(exchange->in_transit);
	free(exchange->nonce_i);
	free(exchange->nonce_r);
	free(exchange->id_i);
	free(exchange->id_r);
	free(exchange->keystate);
	if (exchange->doi && exchange->doi->free_exchange_data)
		exchange->doi->free_exchange_data(exchange->data);
	free(exchange->data);
	free(exchange->name);
	if (exchange->recv_cert) {
		handler = cert_get(exchange->recv_certtype);
		if (handler)
			handler->cert_free(exchange->recv_cert);
	}
	if (exchange->sent_cert) {
		handler = cert_get(exchange->sent_certtype);
		if (handler)
			handler->cert_free(exchange->sent_cert);
	}
	if (exchange->recv_key)
		key_free(exchange->recv_keytype, ISAKMP_KEYTYPE_PUBLIC,
		    exchange->recv_key);
	free(exchange->keynote_key);	/* This is just a string */

	if (exchange->policy_id != -1)
		kn_close(exchange->policy_id);

	exchange_free_aca_list(exchange);
	LIST_REMOVE(exchange, link);

	/* Tell potential finalize routine we never got there.  */
	if (exchange->finalize)
		exchange->finalize(exchange, exchange->finalize_arg, 1);

	/* Remove any SAs that have not been disassociated from us.  */
	for (sa = TAILQ_FIRST(&exchange->sa_list); sa; sa = next_sa) {
		next_sa = TAILQ_NEXT(sa, next);
		/* One for the reference in exchange->sa_list.  */
		sa_release(sa);
		/* And two more for the expiration and SA linked list.  */
		sa_free(sa);
	}

	free(exchange);
}

/* Release all resources this exchange is using.  */
void
exchange_free(struct exchange *exchange)
{
	if (exchange->death)
		timer_remove_event(exchange->death);
	exchange_free_aux(exchange);
}

/*
 * Upgrade the phase 1 exchange and its ISAKMP SA with the rcookie of our
 * peer (found in his recently sent message MSG).
 */
void
exchange_upgrade_p1(struct message *msg)
{
	struct exchange *exchange = msg->exchange;

	LIST_REMOVE(exchange, link);
	GET_ISAKMP_HDR_RCOOKIE(msg->iov[0].iov_base, exchange->cookies +
	    ISAKMP_HDR_ICOOKIE_LEN);
	exchange_enter(exchange);
	sa_isakmp_upgrade(msg);
}

static int
exchange_check_old_sa(struct sa *sa, void *v_arg)
{
	struct sa	*new_sa = v_arg;
	char		 res1[1024];

	if (sa == new_sa || !sa->name || !(sa->flags & SA_FLAG_READY) ||
	    (sa->flags & SA_FLAG_REPLACED))
		return 0;

	if (sa->phase != new_sa->phase || new_sa->name == 0 ||
	    strcasecmp(sa->name, new_sa->name))
		return 0;

	if (sa->initiator)
		strlcpy(res1, ipsec_decode_ids("%s %s", sa->id_i, sa->id_i_len,
		    sa->id_r, sa->id_r_len, 0), sizeof res1);
	else
		strlcpy(res1, ipsec_decode_ids("%s %s", sa->id_r, sa->id_r_len,
		    sa->id_i, sa->id_i_len, 0), sizeof res1);

	LOG_DBG((LOG_EXCHANGE, 30,
	    "checking whether new SA replaces existing SA with IDs %s", res1));

	if (new_sa->initiator)
		return strcasecmp(res1, ipsec_decode_ids("%s %s", new_sa->id_i,
		    new_sa->id_i_len, new_sa->id_r, new_sa->id_r_len, 0)) == 0;
	else
		return strcasecmp(res1, ipsec_decode_ids("%s %s", new_sa->id_r,
		    new_sa->id_r_len, new_sa->id_i, new_sa->id_i_len, 0)) == 0;
}

void
exchange_finalize(struct message *msg)
{
	struct exchange		*exchange = msg->exchange;
	struct sa		*sa, *old_sa;
	struct proto		*proto;
	struct conf_list	*attrs;
	struct conf_list_node	*attr;
	struct cert_handler	*handler;
	int	 i;
	char	*id_doi, *id_trp;

	exchange_dump("exchange_finalize", exchange);

	/* Copy the ID from phase 1 to exchange or phase 2 SA.  */
	if (msg->isakmp_sa) {
		if (exchange->id_i && exchange->id_r) {
			ipsec_clone_id(&msg->isakmp_sa->id_i,
			    &msg->isakmp_sa->id_i_len, exchange->id_i,
			    exchange->id_i_len);
			ipsec_clone_id(&msg->isakmp_sa->id_r,
			    &msg->isakmp_sa->id_r_len, exchange->id_r,
			    exchange->id_r_len);
		} else if (msg->isakmp_sa->id_i && msg->isakmp_sa->id_r) {
			ipsec_clone_id(&exchange->id_i, &exchange->id_i_len,
			    msg->isakmp_sa->id_i, msg->isakmp_sa->id_i_len);
			ipsec_clone_id(&exchange->id_r, &exchange->id_r_len,
			    msg->isakmp_sa->id_r, msg->isakmp_sa->id_r_len);
		}
	}
	/*
         * Walk over all the SAs and noting them as ready.  If we set the
         * COMMIT bit, tell the peer each SA is connected.
         *
         * XXX The decision should really be based on if a SA was installed
         * successfully.
         */
	for (sa = TAILQ_FIRST(&exchange->sa_list); sa;
	    sa = TAILQ_NEXT(sa, next)) {
		/* Move over the name to the SA.  */
		sa->name = exchange->name ? strdup(exchange->name) : 0;

		if (exchange->flags & EXCHANGE_FLAG_I_COMMITTED) {
			for (proto = TAILQ_FIRST(&sa->protos); proto;
			    proto = TAILQ_NEXT(proto, link))
				for (i = 0; i < 2; i++)
					message_send_notification(exchange->last_received,
					    msg->isakmp_sa,
					    ISAKMP_NOTIFY_STATUS_CONNECTED,
					    proto, i);
		}
		/*
		 * Locate any old SAs and mark them replaced
		 * (SA_FLAG_REPLACED).
		 */
		sa->initiator = exchange->initiator;
		while ((old_sa = sa_find(exchange_check_old_sa, sa)) != 0)
			sa_mark_replaced(old_sa);

		/* Setup the SA flags.  */
		sa->flags |= SA_FLAG_READY;
		if (exchange->name) {
			attrs = conf_get_list(exchange->name, "Flags");
			if (attrs) {
				for (attr = TAILQ_FIRST(&attrs->fields); attr;
				    attr = TAILQ_NEXT(attr, link))
					sa->flags |= sa_flag(attr->field);
				conf_free_list(attrs);
			}
			/* 'Connections' should stay alive.  */
			if (connection_exist(exchange->name)) {
				sa->flags |= SA_FLAG_STAYALIVE;

				/*
				 * ISAKMP SA of this connection should also
				 * stay alive.
				 */
				if (exchange->phase == 2 && msg->isakmp_sa)
					msg->isakmp_sa->flags |=
					    SA_FLAG_STAYALIVE;
			}
		}
		sa->seq = exchange->seq;
		sa->exch_type = exchange->type;
	}

	/*
	 * If this was an phase 1 SA negotiation, save the keystate in the
	 * ISAKMP SA structure for future initialization of phase 2 exchanges'
	 * keystates.  Also save the Phase 1 ID and authentication
	 * information.
         */
	if (exchange->phase == 1 && msg->isakmp_sa) {
		msg->isakmp_sa->keystate = exchange->keystate;
		exchange->keystate = 0;

		msg->isakmp_sa->recv_certtype = exchange->recv_certtype;
		msg->isakmp_sa->sent_certtype = exchange->sent_certtype;
		msg->isakmp_sa->recv_keytype = exchange->recv_keytype;
		msg->isakmp_sa->recv_key = exchange->recv_key;
		msg->isakmp_sa->keynote_key = exchange->keynote_key;
		/* Reset.  */
		exchange->recv_key = 0;
		exchange->keynote_key = 0;
		msg->isakmp_sa->policy_id = exchange->policy_id;
		exchange->policy_id = -1;
		msg->isakmp_sa->initiator = exchange->initiator;

		if (exchange->recv_certtype && exchange->recv_cert) {
			handler = cert_get(exchange->recv_certtype);
			if (handler)
				msg->isakmp_sa->recv_cert =
				    handler->cert_dup(exchange->recv_cert);
		}
		if (exchange->sent_certtype) {
			handler = cert_get(exchange->sent_certtype);
			if (handler)
				msg->isakmp_sa->sent_cert =
				    handler->cert_dup(exchange->sent_cert);
		}
		if (exchange->doi)
			id_doi = exchange->doi->decode_ids(
			    "initiator id %s, responder id %s",
			    exchange->id_i, exchange->id_i_len,
			    exchange->id_r, exchange->id_r_len, 0);
		else
			id_doi = "<no doi>";

		if (msg->isakmp_sa->transport)
			id_trp =
			    msg->isakmp_sa->transport->vtbl->decode_ids(msg->isakmp_sa->transport);
		else
			id_trp = "<no transport>";

		if (exchange->flags & EXCHANGE_FLAG_NAT_T_ENABLE)
			msg->isakmp_sa->flags |= SA_FLAG_NAT_T_ENABLE;
		if (exchange->flags & EXCHANGE_FLAG_NAT_T_KEEPALIVE)
			msg->isakmp_sa->flags |= SA_FLAG_NAT_T_KEEPALIVE;

		LOG_DBG((LOG_EXCHANGE, 10,
		    "exchange_finalize: phase 1 done: %s, %s", id_doi,
		    id_trp));

		log_verbose("isakmpd: phase 1 done%s: %s, %s",
			(exchange->initiator == 0) ? " (as responder)" : "",
			id_doi, id_trp);
	}
	exchange->doi->finalize_exchange(msg);
	if (exchange->finalize)
		exchange->finalize(exchange, exchange->finalize_arg, 0);
	exchange->finalize = 0;

	/*
         * There is no reason to keep the SAs connected to us anymore, in fact
         * it can hurt us if we have short lifetimes on the SAs and we try
         * to call exchange_report, where the SA list will be walked and
         * references to freed SAs can occur.
         */
	while (TAILQ_FIRST(&exchange->sa_list)) {
		sa = TAILQ_FIRST(&exchange->sa_list);

		if (exchange->id_i && exchange->id_r) {
			ipsec_clone_id(&sa->id_i, &sa->id_i_len,
			    exchange->id_i, exchange->id_i_len);
			ipsec_clone_id(&sa->id_r, &sa->id_r_len,
			    exchange->id_r, exchange->id_r_len);
		}
		TAILQ_REMOVE(&exchange->sa_list, sa, next);
		sa_release(sa);
	}
	/*
	 * Start sending DPD messages after all SAs have been released.
	 * Otherwise we have a race between exchange_free_aux() and
	 * dpd_check_event() where both will call sa_free().
	 */
	if (exchange->phase == 1 && msg->isakmp_sa &&
	    (exchange->flags & EXCHANGE_FLAG_DPD_CAP_PEER))
		dpd_start(msg->isakmp_sa);

	/* If we have nothing to retransmit we can safely remove ourselves.  */
	if (!exchange->last_sent)
		exchange_free(exchange);
}

/* Stash a nonce into the exchange data.  */
static int
exchange_nonce(struct exchange *exchange, int peer, size_t nonce_sz,
    u_int8_t *buf)
{
	u_int8_t      **nonce;
	size_t         *nonce_len;
	int		initiator = exchange->initiator ^ peer;
	char            header[32];

	if (nonce_sz < 8 || nonce_sz > 256) {
		/*
		 * RFC2409, ch 5: The length of nonce payload MUST be
		 * between 8 and 256 bytes inclusive.
		 * XXX I'm assuming the generic payload header is not included.
		 */
		LOG_DBG((LOG_EXCHANGE, 20,
		    "exchange_nonce: invalid nonce length %lu",
		    (unsigned long)nonce_sz));
		return -1;
	}

	nonce = initiator ? &exchange->nonce_i : &exchange->nonce_r;
	nonce_len =
	    initiator ? &exchange->nonce_i_len : &exchange->nonce_r_len;
	*nonce_len = nonce_sz;
	*nonce = malloc(nonce_sz);
	if (!*nonce) {
		log_error("exchange_nonce: malloc (%lu) failed",
		    (unsigned long)nonce_sz);
		return -1;
	}
	memcpy(*nonce, buf, nonce_sz);
	snprintf(header, sizeof header, "exchange_nonce: NONCE_%c",
	    initiator ? 'i' : 'r');
	LOG_DBG_BUF((LOG_EXCHANGE, 80, header, *nonce, nonce_sz));
	return 0;
}

/* Generate our NONCE.  */
int
exchange_gen_nonce(struct message *msg, size_t nonce_sz)
{
	struct exchange *exchange = msg->exchange;
	u_int8_t	*buf;

	buf = malloc(ISAKMP_NONCE_SZ + nonce_sz);
	if (!buf) {
		log_error("exchange_gen_nonce: malloc (%lu) failed",
		    ISAKMP_NONCE_SZ + (unsigned long)nonce_sz);
		return -1;
	}
	arc4random_buf(buf + ISAKMP_NONCE_DATA_OFF, nonce_sz);
	if (message_add_payload(msg, ISAKMP_PAYLOAD_NONCE, buf,
	    ISAKMP_NONCE_SZ + nonce_sz, 1)) {
		free(buf);
		return -1;
	}
	return exchange_nonce(exchange, 0, nonce_sz,
	    buf + ISAKMP_NONCE_DATA_OFF);
}

/* Save the peer's NONCE.  */
int
exchange_save_nonce(struct message *msg)
{
	struct payload	*noncep;
	struct exchange *exchange = msg->exchange;

	noncep = payload_first(msg, ISAKMP_PAYLOAD_NONCE);
	noncep->flags |= PL_MARK;
	return exchange_nonce(exchange, 1, GET_ISAKMP_GEN_LENGTH(noncep->p) -
	    ISAKMP_NONCE_DATA_OFF, noncep->p + ISAKMP_NONCE_DATA_OFF);
}

/* Save the peer's CERT REQuests.  */
int
exchange_save_certreq(struct message *msg)
{
	struct payload	*cp;
	struct exchange	*exchange = msg->exchange;
	struct certreq_aca *aca;

	TAILQ_FOREACH(cp, &msg->payload[ISAKMP_PAYLOAD_CERT_REQ], link) {
		cp->flags |= PL_MARK;
		aca = certreq_decode(GET_ISAKMP_CERTREQ_TYPE(cp->p), cp->p +
		    ISAKMP_CERTREQ_AUTHORITY_OFF, GET_ISAKMP_GEN_LENGTH(cp->p)
		    - ISAKMP_CERTREQ_AUTHORITY_OFF);
		if (aca)
			TAILQ_INSERT_TAIL(&exchange->aca_list, aca, link);
	}

	return 0;
}

/* Free the list of pending CERTREQs.  */
void
exchange_free_aca_list(struct exchange *exchange)
{
	struct certreq_aca *aca;

	for (aca = TAILQ_FIRST(&exchange->aca_list); aca;
	    aca = TAILQ_FIRST(&exchange->aca_list)) {
		if (aca->raw_ca)
			free(aca->raw_ca);
		if (aca->data) {
			if (aca->handler)
				aca->handler->free_aca(aca->data);
			free(aca->data);
		}
		TAILQ_REMOVE(&exchange->aca_list, aca, link);
		free(aca);
	}
}

/* Add any CERTREQs we should send.  */
int
exchange_add_certreqs(struct message *msg)
{
	struct exchange *exchange = msg->exchange;
	struct certreq_aca *aca;
	u_int8_t *buf;

	/*
	 * Some peers (e.g. Cisco IOS) won't send their cert unless we
	 * specifically ask beforehand with CERTREQ.  We reflect any
	 * CERTREQs we receive from the initiator in order to do this.
	 * This avoids leaking information about which CAs we trust,
	 * and works in the most common case where both ends trust the
	 * same CA.
	 */
	for (aca = TAILQ_FIRST(&exchange->aca_list); aca;
	    aca = TAILQ_NEXT(aca, link)) {

		/* But only do this if we have at least one CA */
		if (aca->handler != NULL && aca->handler->ca_count() == 0) {
			LOG_DBG((LOG_EXCHANGE, 10,
			    "exchange_add_certreqs: no CA, so not "
			    "sending a CERTREQ"));
			continue;
		}

		if (aca->raw_ca_len) {
			buf = malloc(ISAKMP_CERTREQ_SZ + aca->raw_ca_len);
			if (buf == NULL) {
				log_error("exchange_add_certreqs: "
				    "malloc (%lu) failed",
				    ISAKMP_CERTREQ_SZ +
				    (unsigned long)aca->raw_ca_len);
				return -1;
			}

			buf[ISAKMP_CERTREQ_TYPE_OFF] = aca->id;
			memcpy(buf + ISAKMP_CERTREQ_AUTHORITY_OFF,
			    aca->raw_ca, aca->raw_ca_len);

			if (message_add_payload(msg, ISAKMP_PAYLOAD_CERT_REQ,
			    buf, ISAKMP_CERTREQ_SZ + aca->raw_ca_len, 1)) {
				free(buf);
				return -1;
			}
		}
	}

	return 0;
}

/* Obtain certificates from acceptable certification authority.  */
int
exchange_add_certs(struct message *msg)
{
	struct exchange *exchange = msg->exchange;
	struct certreq_aca *aca;
	u_int8_t       *cert = 0, *new_cert = 0;
	u_int32_t       certlen;
	u_int8_t       *id;
	size_t          id_len;

	id = exchange->initiator ? exchange->id_r : exchange->id_i;
	id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;

	/*
         * Without IDs we cannot handle this yet. Keep the aca_list around for
         * a later step/retry to see if we got the ID by then.
         * Note: A 'return -1' breaks X509-auth interop in the responder case
         *       with some IPsec clients that send CERTREQs early (such as
	 *       the SSH Sentinel).
         */
	if (!id)
		return 0;

	for (aca = TAILQ_FIRST(&exchange->aca_list); aca;
	    aca = TAILQ_NEXT(aca, link)) {
		/* XXX? If we can not satisfy a CERTREQ we drop the message. */
		if (!aca->handler->cert_obtain(id, id_len, aca->data, &cert,
		    &certlen)) {
			log_print("exchange_add_certs: could not obtain cert "
			    "for a type %d cert request", aca->id);
			free(cert);
			return -1;
		}
		new_cert = realloc(cert, ISAKMP_CERT_SZ + certlen);
		if (!new_cert) {
			log_error("exchange_add_certs: realloc (%p, %d) "
			    "failed", cert, ISAKMP_CERT_SZ + certlen);
			free(cert);
			return -1;
		}
		cert = new_cert;
		memmove(cert + ISAKMP_CERT_DATA_OFF, cert, certlen);
		SET_ISAKMP_CERT_ENCODING(cert, aca->id);
		if (message_add_payload(msg, ISAKMP_PAYLOAD_CERT, cert,
		    ISAKMP_CERT_SZ + certlen, 1)) {
			free(cert);
			return -1;
		}
		/*
		 * We need to reset cert here, as it is now controlled by
		 * message_add_payload() (i.e. we must not free() it), and
		 * it is possible for the next iteration of the aca loop
		 * to fail early in cert_obtain before it writes to &cert.
		 */
		cert = NULL;
	}

	/* We dont need the CERT REQs any more, they are answered.  */
	exchange_free_aca_list(exchange);

	return 0;
}

static void
exchange_establish_finalize(struct exchange *exchange, void *arg, int fail)
{
	char	*name = arg;

	LOG_DBG((LOG_EXCHANGE, 20, "exchange_establish_finalize: "
	    "finalizing exchange %p with arg %p (%s) & fail = %d",
	    exchange, arg, name ? name : "<unnamed>", fail));

	if (!fail)
		exchange_establish(name, 0, 0, 0);
	free(name);
}

/*
 * Establish an exchange named NAME, and record the FINALIZE function
 * taking ARG as an argument to be run after the exchange is ready.
 */
void
exchange_establish(char *name, void (*finalize)(struct exchange *, void *,
    int), void *arg, int stayalive)
{
	struct transport	*transport;
	struct sa		*isakmp_sa;
	struct exchange		*exchange;
	int	 phase;
	char	*trpt, *peer;

	phase = conf_get_num(name, "Phase", 0);

	if (ui_daemon_passive) {
		LOG_DBG((LOG_EXCHANGE, 40, "exchange_establish:"
		    " returning in passive mode for exchange %s phase %d",
		    name, phase));
		return;
	}

	/*
	 * First of all, never try to establish anything if another exchange
	 * of the same kind is running.
         */
	exchange = exchange_lookup_by_name(name, phase);
	if (exchange) {
		LOG_DBG((LOG_EXCHANGE, 40,
		    "exchange_establish: %s exchange already exists as %p",
		    name, exchange));
		exchange_add_finalization(exchange, finalize, arg);
		return;
	}
	switch (phase) {
	case 1:
		trpt = conf_get_str(name, "Transport");
		if (!trpt) {
			/* Phase 1 transport defaults to "udp".  */
			trpt = ISAKMP_DEFAULT_TRANSPORT;
		}
		transport = transport_create(trpt, name);
		if (!transport) {
			log_print("exchange_establish: transport \"%s\" for "
			    "peer \"%s\" could not be created", trpt, name);
			return;
		}
		exchange_establish_p1(transport, 0, 0, name, 0, finalize, arg,
		    stayalive);
		break;

	case 2:
		peer = conf_get_str(name, "ISAKMP-peer");
		if (!peer) {
			log_print("exchange_establish: No ISAKMP-peer given "
			    "for \"%s\"", name);
			return;
		}
		isakmp_sa = sa_lookup_by_name(peer, 1);
		if (!isakmp_sa) {
			name = strdup(name);
			if (!name) {
				log_error("exchange_establish: "
				    "strdup (\"%s\") failed", name);
				return;
			}
			if (conf_get_num(peer, "Phase", 0) != 1) {
				log_print("exchange_establish: "
				    "[%s]:ISAKMP-peer's (%s) phase is not 1",
				    name, peer);
				free(name);
				return;
			}
			/*
			 * XXX We're losing information here (what the
			 * original finalize routine was. As a result, if an
			 * exchange does not manage to get through, there may
			 * be application-specific information that won't get
			 * cleaned up, since no error signaling will be done.
			 * This is the case with dynamic SAs and PFKEY.
			 */
			exchange_establish(peer, exchange_establish_finalize,
			    name, 0);
			exchange = exchange_lookup_by_name(peer, 1);
			/*
			 * If the exchange was correctly initialized, add the
			 * original finalization routine; otherwise, call it
			 * directly.
			 */
			if (exchange)
				exchange_add_finalization(exchange, finalize,
				    arg);
			else {
				/* Indicate failure */
				if (finalize)
					finalize(0, arg, 1);
				free(name);
			}
			return;
		} else
			exchange_establish_p2(isakmp_sa, 0, name, 0, finalize,
			    arg);
		break;

	default:
		log_print("exchange_establish: "
		    "peer \"%s\" does not have a correct phase (%d)",
		    name, phase);
		break;
	}
}