/* 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.
 */

#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)
	{
		free(fg_path);
		fg_path_space = plen + 10;
		fg_path = malloc(fg_path_space);
	}
	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 = malloc_thing(struct fg_targets);

							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;
		free(t->name);
		free(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 = malloc_thing(struct fg_groups);

	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);
				free(t);
				/* pp is ready for next iteration */
			}
			else
			{
				pp = &t->next;
			}
		}
	}

	free(g);
}