/* Implement policy groups-style control files (aka "foodgroups")
 * Copyright (C) 2002  D. Hugh Redelmeier.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * RCSID $Id$
 */

#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <sys/queue.h>

#include <freeswan.h>

#include "constants.h"
#include "defs.h"
#include "connections.h"
#include "foodgroups.h"
#include "kernel.h"
#include "lex.h"
#include "log.h"
#include "whack.h"


/* Food group config files are found in directory fg_path */

#ifndef POLICYGROUPSDIR
#define POLICYGROUPSDIR IPSEC_CONFDIR "/ipsec.d/policies"
#endif

const char *policygroups_dir = POLICYGROUPSDIR;

static char *fg_path = NULL;
static size_t fg_path_space = 0;


/* Groups is a list of connections that are policy groups.
 * The list is updated as group connections are added and deleted.
 */

struct fg_groups {
    struct fg_groups *next;
    struct connection *connection;
};

static struct fg_groups *groups = NULL;


/* Targets is a list of pairs: subnet and its policy group.
 * This list is bulk-updated on whack --listen and
 * incrementally updated when group connections are deleted.
 *
 * It is ordered by source subnet, and if those are equal, then target subnet.
 * A subnet is compared by comparing the network, and if those are equal,
 * comparing the mask.
 */

struct fg_targets {
    struct fg_targets *next;
    struct fg_groups *group;
    ip_subnet subnet;
    char *name;	/* name of instance of group conn */
};

static struct fg_targets *targets = NULL;

struct fg_targets *new_targets;

/* ipcmp compares the two ip_address values a and b.
 * It returns -1, 0, or +1 if a is, respectively,
 * less than, equal to, or greater than b.
 */
static int
ipcmp(ip_address *a, ip_address *b)
{
    if (addrtypeof(a) != addrtypeof(b))
    {
	return addrtypeof(a) < addrtypeof(b)? -1 : 1;
    }
    else if (sameaddr(a, b))
    {
	return 0;
    }
    else
    {
	const struct sockaddr *sa = sockaddrof(a)
	    , *sb = sockaddrof(b);

	passert(addrtypeof(a) == AF_INET);	/* not yet implemented IPv6 version :-( */
	return (ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr)
	    < ntohl(((const struct sockaddr_in *)sb)->sin_addr.s_addr))
	    ? -1 : 1;
    }
}

/* subnetcmp compares the two ip_subnet values a and b.
 * It returns -1, 0, or +1 if a is, respectively,
 * less than, equal to, or greater than b.
 */
static int
subnetcmp(const ip_subnet *a, const ip_subnet *b)
{
    ip_address neta, maska, netb, maskb;
    int r;

    networkof(a, &neta);
    maskof(a, &maska);
    networkof(b, &netb);
    maskof(b, &maskb);
    r = ipcmp(&neta, &netb);
    if (r == 0)
	r = ipcmp(&maska, &maskb);
    return r;
}

static void
read_foodgroup(struct fg_groups *g)
{
    const char *fgn = g->connection->name;
    const ip_subnet *lsn = &g->connection->spd.this.client;
    size_t plen = strlen(policygroups_dir) + 1 + strlen(fgn) + 1;
    struct file_lex_position flp_space;

    if (plen > fg_path_space)
    {
	pfreeany(fg_path);
	fg_path_space = plen + 10;
	fg_path = alloc_bytes(fg_path_space, "policy group path");
    }
    snprintf(fg_path, fg_path_space, "%s/%s", policygroups_dir, fgn);
    if (!lexopen(&flp_space, fg_path, TRUE))
    {
	DBG(DBG_CONTROL, DBG_log("no group file \"%s\"", fg_path));
    }
    else
    {
	plog("loading group \"%s\"", fg_path);
	for (;;)
	{
	    switch (flp->bdry)
	    {
	    case B_none:
		{
		    /* !!! this test is not sufficient for distinguishing address families.
		     * We need a notation to specify that a FQDN is to be resolved to IPv6.
		     */
		    const struct af_info *afi = strchr(tok, ':') == NULL
			? &af_inet4_info: &af_inet6_info;
		    ip_subnet sn;
		    err_t ugh;

		    if (strchr(tok, '/') == NULL)
		    {
			/* no /, so treat as /32 or V6 equivalent */
			ip_address t;

			ugh = ttoaddr(tok, 0, afi->af, &t);
			if (ugh == NULL)
			    ugh = addrtosubnet(&t, &sn);
		    }
		    else
		    {
			ugh = ttosubnet(tok, 0, afi->af, &sn);
		    }

		    if (ugh != NULL)
		    {
			loglog(RC_LOG_SERIOUS, "\"%s\" line %d: %s \"%s\""
			    , flp->filename, flp->lino, ugh, tok);
		    }
		    else if (afi->af != AF_INET)
		    {
			loglog(RC_LOG_SERIOUS
			    , "\"%s\" line %d: unsupported Address Family \"%s\""
			    , flp->filename, flp->lino, tok);
		    }
		    else
		    {
			/* Find where new entry ought to go in new_targets. */
			struct fg_targets **pp;
			int r;

			for (pp = &new_targets; ; pp = &(*pp)->next)
			{
			    if (*pp == NULL)
			    {
				r = -1;	/* end of list is infinite */
				break;
			    }
			    r = subnetcmp(lsn, &(*pp)->group->connection->spd.this.client);
			    if (r == 0)
				r = subnetcmp(&sn, &(*pp)->subnet);
			    if (r <= 0)
				break;
			}

			if (r == 0)
			{
			    char source[SUBNETTOT_BUF];

			    subnettot(lsn, 0, source, sizeof(source));
			    loglog(RC_LOG_SERIOUS
				, "\"%s\" line %d: subnet \"%s\", source %s, already \"%s\""
				, flp->filename
				, flp->lino
				, tok
				, source
				, (*pp)->group->connection->name);
			}
			else
			{
			    struct fg_targets *f = alloc_thing(struct fg_targets, "fg_target");

			    f->next = *pp;
			    f->group = g;
			    f->subnet = sn;
			    f->name = NULL;
			    *pp = f;
			}
		    }
		}
		(void)shift();	/* next */
		continue;

	    case B_record:
		flp->bdry = B_none;	/* eat the Record Boundary */
		(void)shift();	/* get real first token */
		continue;

	    case B_file:
		break;	/* done */
	    }
	    break;	/* if we reach here, out of loop */
	}
	lexclose();
    }
}

static void
free_targets(void)
{
    while (targets != NULL)
    {
	struct fg_targets *t = targets;

	targets = t->next;
	pfreeany(t->name);
	pfree(t);
    }
}

void
load_groups(void)
{
    passert(new_targets == NULL);

    /* for each group, add config file targets into new_targets */
    {
	struct fg_groups *g;

	for (g = groups; g != NULL; g = g->next)
	    if (oriented(*g->connection))
		read_foodgroup(g);
    }

    /* dump new_targets */
    DBG(DBG_CONTROL,
	{
	    struct fg_targets *t;

	    for (t = new_targets; t != NULL; t = t->next)
	    {
		char asource[SUBNETTOT_BUF];
		char atarget[SUBNETTOT_BUF];

		subnettot(&t->group->connection->spd.this.client
		    , 0, asource, sizeof(asource));
		subnettot(&t->subnet, 0, atarget, sizeof(atarget));
		DBG_log("%s->%s %s"
		    , asource, atarget
		    , t->group->connection->name);
	    }
	});

    /* determine and deal with differences between targets and new_targets.
     * structured like a merge.
     */
    {
	struct fg_targets *op = targets
	    , *np = new_targets;

	while (op != NULL && np != NULL)
	{
	    int r = subnetcmp(&op->group->connection->spd.this.client
		, &np->group->connection->spd.this.client);

	    if (r == 0)
		r = subnetcmp(&op->subnet, &np->subnet);

	    if (r == 0 && op->group == np->group)
	    {
		/* unchanged -- steal name & skip over */
		np->name = op->name;
		op->name = NULL;
		op = op->next;
		np = np->next;
	    }
	    else
	    {
		/* note: following cases overlap! */
		if (r <= 0)
		{
		    remove_group_instance(op->group->connection, op->name);
		    op = op->next;
		}
		if (r >= 0)
		{
		    np->name = add_group_instance(np->group->connection, &np->subnet);
		    np = np->next;
		}
	    }
	}
	for (; op != NULL; op = op->next)
	    remove_group_instance(op->group->connection, op->name);
	for (; np != NULL; np = np->next)
	    np->name = add_group_instance(np->group->connection, &np->subnet);

	/* update: new_targets replaces targets */
	free_targets();
	targets = new_targets;
	new_targets = NULL;
    }
}


void
add_group(struct connection *c)
{
    struct fg_groups *g = alloc_thing(struct fg_groups, "policy group");

    g->next = groups;
    groups = g;

    g->connection = c;
}

static struct fg_groups *
find_group(const struct connection *c)
{
    struct fg_groups *g;

    for (g = groups; g != NULL && g->connection != c; g = g->next)
	;
    return g;
}

void
route_group(struct connection *c)
{
    /* it makes no sense to route a connection that is ISAKMP-only */
    if (!NEVER_NEGOTIATE(c->policy) && !HAS_IPSEC_POLICY(c->policy))
    {
	loglog(RC_ROUTE, "cannot route an ISAKMP-only group connection");
    }
    else
    {
	struct fg_groups *g = find_group(c);
	struct fg_targets *t;

	passert(g != NULL);
	g->connection->policy |= POLICY_GROUTED;
	for (t = targets; t != NULL; t = t->next)
	{
	    if (t->group == g)
	    {
		struct connection *ci = con_by_name(t->name, FALSE);

		if (ci != NULL)
		{
		    set_cur_connection(ci);
		    if (!trap_connection(ci))
			whack_log(RC_ROUTE, "could not route");
		    set_cur_connection(c);
		}
	    }
	}
    }
}

void
unroute_group(struct connection *c)
{
    struct fg_groups *g = find_group(c);
    struct fg_targets *t;

    passert(g != NULL);
    g->connection->policy &= ~POLICY_GROUTED;
    for (t = targets; t != NULL; t = t->next)
    {
	if (t->group == g)
	{
	    struct connection *ci = con_by_name(t->name, FALSE);

	    if (ci != NULL)
	    {
		set_cur_connection(ci);
		unroute_connection(ci);
		set_cur_connection(c);
	    }
	}
    }
}

void
delete_group(const struct connection *c)
{
    struct fg_groups *g;

    /* find and remove from groups */
    {
	struct fg_groups **pp;

	for (pp = &groups; (g = *pp)->connection != c; pp = &(*pp)->next)
	    ;

	*pp = g->next;
    }

    /* find and remove from targets */
    {
	struct fg_targets **pp;

	for (pp = &targets; *pp != NULL; )
	{
	    struct fg_targets *t = *pp;

	    if (t->group == g)
	    {
		*pp = t->next;
		remove_group_instance(t->group->connection, t->name);
		pfree(t);
		/* pp is ready for next iteration */
	    }
	    else
	    {
		pp = &t->next;
	    }
	}
    }

    pfree(g);
}
