/* IKE modular algorithm handling interface
 * Copyright (C) JuanJo Ciarlante <jjo-ipsec@mendoza.gov.ar>
 * Copyright (C) 2009 Andreas Steffen - Hochschule fuer Technik Rapperswil
 *
 * 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 <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/queue.h>

#include <freeswan.h>

#include <library.h>
#include <debug.h>
#include <credentials/keys/public_key.h>
#include <credentials/keys/private_key.h>
#include <crypto/hashers/hasher.h>
#include <crypto/crypters/crypter.h>
#include <crypto/prfs/prf.h>

#include "constants.h"
#include "defs.h"
#include "crypto.h"
#include "state.h"
#include "packet.h"
#include "keys.h"
#include "log.h"
#include "whack.h"
#include "spdb.h"
#include "alg_info.h"
#include "ike_alg.h"
#include "db_ops.h"
#include "connections.h"
#include "kernel.h"

#define return_on(var, val) do { var=val;goto return_out; } while(0);

/**
 * IKE algorithm list handling - registration and lookup
 */

/* Modular IKE algorithm storage structure */

static struct ike_alg *ike_alg_base[IKE_ALG_MAX+1] = {NULL, NULL};

/**
 * Return ike_algo object by {type, id}
 */
static struct ike_alg *ike_alg_find(u_int algo_type, u_int algo_id,
									u_int keysize __attribute__((unused)))
{
	struct ike_alg *e = ike_alg_base[algo_type];

	while (e != NULL && algo_id > e->algo_id)
	{
		e = e->algo_next;
	}
	return (e != NULL && e->algo_id == algo_id) ? e : NULL;
}

/**
 * "raw" ike_alg list adding function
 */
int ike_alg_add(struct ike_alg* a)
{
	if (a->algo_type > IKE_ALG_MAX)
	{
		plog("ike_alg: Not added, invalid algorithm type");
		return -EINVAL;
	}

	if (ike_alg_find(a->algo_type, a->algo_id, 0) != NULL)
	{
		plog("ike_alg: Not added, algorithm already exists");
		return -EEXIST;
	}

	{
		struct ike_alg **ep = &ike_alg_base[a->algo_type];
		struct ike_alg *e = *ep;

		while (e != NULL && a->algo_id > e->algo_id)
		{
			ep = &e->algo_next;
			e = *ep;
		}
		*ep = a;
		a->algo_next = e;
		return 0;
	}
}

/**
 * Get IKE hash algorithm
 */
struct hash_desc *ike_alg_get_hasher(u_int alg)
{
	return (struct hash_desc *) ike_alg_find(IKE_ALG_HASH, alg, 0);
}

/**
 * Get IKE encryption algorithm
 */
struct encrypt_desc *ike_alg_get_crypter(u_int alg)
{
	return (struct encrypt_desc *) ike_alg_find(IKE_ALG_ENCRYPT, alg, 0);
}

/**
 * Get IKE dh group
 */
struct dh_desc *ike_alg_get_dh_group(u_int alg)
{
	return (struct dh_desc *) ike_alg_find(IKE_ALG_DH_GROUP, alg, 0);
}

/**
 * Get pfsgroup for this connection
 */
const struct dh_desc *ike_alg_pfsgroup(connection_t *c, lset_t policy)
{
	const struct dh_desc *ret = NULL;

	if ((policy & POLICY_PFS) &&
		c->alg_info_esp && c->alg_info_esp->esp_pfsgroup)
	{
		ret = ike_alg_get_dh_group(c->alg_info_esp->esp_pfsgroup);
	}
	return ret;
}

/**
 * Create an OAKLEY proposal based on alg_info and policy
 */
struct db_context *ike_alg_db_new(connection_t *c, lset_t policy)
{
	struct alg_info_ike *ai = c->alg_info_ike;
	struct db_context *db_ctx = NULL;
	struct ike_info *ike_info;
	struct encrypt_desc *enc_desc;
	u_int ealg, halg, modp, eklen = 0;
	int i;

	bool is_xauth_server = (policy & POLICY_XAUTH_SERVER) != LEMPTY;

	if (!ai)
	{
		whack_log(RC_LOG_SERIOUS, "no IKE algorithms "
								  "for this connection "
								  "(check ike algorithm string)");
		goto fail;
	}
	policy &= POLICY_ID_AUTH_MASK;
	db_ctx = db_prop_new(PROTO_ISAKMP, 8, 8 * 5);

	/* for each group */
	ALG_INFO_IKE_FOREACH(ai, ike_info, i)
	{
		ealg = ike_info->ike_ealg;
		halg = ike_info->ike_halg;
		modp = ike_info->ike_modp;
		eklen= ike_info->ike_eklen;

		if (!ike_alg_get_crypter(ealg))
		{
			plog("ike alg: crypter %s not present",
					enum_show(&oakley_enc_names, ealg));
			continue;
		}
		if (!ike_alg_get_hasher(halg))
		{
			plog("ike alg: hasher %s not present",
					enum_show(&oakley_hash_names, halg));
			continue;
		}
		if (!ike_alg_get_dh_group(modp))
		{
			plog("ike alg: dh group %s not present",
					enum_show(&oakley_group_names, modp));
			continue;
		}
		enc_desc = ike_alg_get_crypter(ealg);

		if (policy & POLICY_PUBKEY)
		{
			int auth_method = 0;
			size_t key_size = 0;
			key_type_t key_type = KEY_ANY;


			if (c->spd.this.cert)
			{
				certificate_t *certificate = c->spd.this.cert->cert;
				public_key_t *key = certificate->get_public_key(certificate);

				if (key == NULL)
				{				
					plog("ike alg: unable to retrieve my public key");
					continue;
				}
				key_type = key->get_type(key);
				key_size = key->get_keysize(key);
				key->destroy(key);
			}
			else
			{
				private_key_t *key = get_private_key(c);

				if (key == NULL)
				{
					plog("ike alg: unable to retrieve my private key");
					continue;
				}
				key_type = key->get_type(key);
				key_size = key->get_keysize(key);
			}
			switch (key_type)
			{
				case KEY_RSA:
					auth_method = OAKLEY_RSA_SIG;
					break;
				case KEY_ECDSA:
					switch (key_size)
					{
						case 32:
							auth_method = OAKLEY_ECDSA_256;
							break;
						case 48:
							auth_method = OAKLEY_ECDSA_384;
							break;
						case 66:
							auth_method = OAKLEY_ECDSA_521;
							break;
						default:
							continue;
					}
					break;
				default:
					continue;
			}
			db_trans_add(db_ctx, KEY_IKE);
			db_attr_add_values(db_ctx, OAKLEY_ENCRYPTION_ALGORITHM, ealg);
			db_attr_add_values(db_ctx, OAKLEY_HASH_ALGORITHM, halg);
			if (eklen)
			{
				db_attr_add_values(db_ctx, OAKLEY_KEY_LENGTH, eklen);
			}
			db_attr_add_values(db_ctx, OAKLEY_AUTHENTICATION_METHOD, auth_method);
			db_attr_add_values(db_ctx, OAKLEY_GROUP_DESCRIPTION, modp);
		}

		if (policy & POLICY_PSK)
		{
			db_trans_add(db_ctx, KEY_IKE);
			db_attr_add_values(db_ctx, OAKLEY_ENCRYPTION_ALGORITHM, ealg);
			db_attr_add_values(db_ctx, OAKLEY_HASH_ALGORITHM, halg);
			if (eklen)
			{
				db_attr_add_values(db_ctx, OAKLEY_KEY_LENGTH, eklen);
			}
			db_attr_add_values(db_ctx, OAKLEY_AUTHENTICATION_METHOD, OAKLEY_PRESHARED_KEY);
			db_attr_add_values(db_ctx, OAKLEY_GROUP_DESCRIPTION, modp);
		}

		if (policy & POLICY_XAUTH_RSASIG)
		{
			db_trans_add(db_ctx, KEY_IKE);
			db_attr_add_values(db_ctx, OAKLEY_ENCRYPTION_ALGORITHM, ealg);
			db_attr_add_values(db_ctx, OAKLEY_HASH_ALGORITHM, halg);
			if (eklen)
			{
				db_attr_add_values(db_ctx, OAKLEY_KEY_LENGTH, eklen);
			}
			db_attr_add_values(db_ctx, OAKLEY_AUTHENTICATION_METHOD
				, is_xauth_server ? XAUTHRespRSA : XAUTHInitRSA);
			db_attr_add_values(db_ctx, OAKLEY_GROUP_DESCRIPTION, modp);
		}

		if (policy & POLICY_XAUTH_PSK)
		{
			db_trans_add(db_ctx, KEY_IKE);
			db_attr_add_values(db_ctx, OAKLEY_ENCRYPTION_ALGORITHM, ealg);
			db_attr_add_values(db_ctx, OAKLEY_HASH_ALGORITHM, halg);
			if (eklen)
			{
				db_attr_add_values(db_ctx, OAKLEY_KEY_LENGTH, eklen);
			}
			db_attr_add_values(db_ctx, OAKLEY_AUTHENTICATION_METHOD
				, is_xauth_server ? XAUTHRespPreShared : XAUTHInitPreShared);
			db_attr_add_values(db_ctx, OAKLEY_GROUP_DESCRIPTION, modp);
		}
	}
fail:
	return db_ctx;
}

/**
 * Show registered IKE algorithms
 */
void ike_alg_list(void)
{
	char buf[BUF_LEN];
	char *pos;
	int n, len;
	struct ike_alg *a;

	whack_log(RC_COMMENT, " ");
	whack_log(RC_COMMENT, "List of registered IKEv1 Algorithms:");
	whack_log(RC_COMMENT, " ");

	pos = buf;
	*pos = '\0';
	len = BUF_LEN;
	for (a = ike_alg_base[IKE_ALG_ENCRYPT]; a != NULL; a = a->algo_next)
	{
	    n = snprintf(pos, len, " %s", enum_name(&oakley_enc_names, a->algo_id));
		pos += n;
		len -= n;
		if (len <= 0)
		{
			break;
		}
	}
	whack_log(RC_COMMENT, "  encryption:%s", buf);

	pos = buf;
	*pos = '\0';
	len = BUF_LEN;
	for (a = ike_alg_base[IKE_ALG_HASH]; a != NULL; a = a->algo_next)
	{
	    n = snprintf(pos, len, " %s", enum_name(&oakley_hash_names, a->algo_id));
		pos += n;
		len -= n;
		if (len <= 0)
		{
			break;
		}
	}
	whack_log(RC_COMMENT, "  integrity: %s", buf);

	pos = buf;
	*pos = '\0';
	len = BUF_LEN;
	for (a = ike_alg_base[IKE_ALG_DH_GROUP]; a != NULL; a = a->algo_next)
	{
	    n = snprintf(pos, len, " %s", enum_name(&oakley_group_names, a->algo_id));
		pos += n;
		len -= n;
		if (len <= 0)
		{
			break;
		}
	}
	whack_log(RC_COMMENT, "  dh-group:  %s", buf);
}

/**
 * Show IKE algorithms for this connection (result from ike= string)
 * and newest SA
 */
void ike_alg_show_connection(connection_t *c, const char *instance)
{
	struct state *st = state_with_serialno(c->newest_isakmp_sa);

	if (st)
	{
		if (st->st_oakley.encrypt == OAKLEY_3DES_CBC)
		{
			whack_log(RC_COMMENT,
					"\"%s\"%s:   IKE proposal: %s/%s/%s",
					c->name, instance,
					enum_show(&oakley_enc_names, st->st_oakley.encrypt),
					enum_show(&oakley_hash_names, st->st_oakley.hash),
					enum_show(&oakley_group_names, st->st_oakley.group->algo_id)
			);
		}
		else
		{
			whack_log(RC_COMMENT,
					"\"%s\"%s:   IKE proposal: %s_%u/%s/%s",
					c->name, instance,
					enum_show(&oakley_enc_names, st->st_oakley.encrypt),
					st->st_oakley.enckeylen,
					enum_show(&oakley_hash_names, st->st_oakley.hash),
					enum_show(&oakley_group_names, st->st_oakley.group->algo_id)
			);
		}
	}
}

/**
 * ML: make F_STRICT logic consider enc,hash/auth,modp algorithms
 */
bool ike_alg_ok_final(u_int ealg, u_int key_len, u_int aalg, u_int group,
					  struct alg_info_ike *alg_info_ike)
{
	/*
	 * simple test to discard low key_len, will accept it only
	 * if specified in "esp" string
	 */
	bool ealg_insecure = (key_len < 128);

	if (ealg_insecure
	|| (alg_info_ike && alg_info_ike->alg_info_flags & ALG_INFO_F_STRICT))
	{
		int i;
		struct ike_info *ike_info;

		if (alg_info_ike)
		{
			ALG_INFO_IKE_FOREACH(alg_info_ike, ike_info, i)
			{
				if (ike_info->ike_ealg == ealg
				&& (ike_info->ike_eklen == 0 || key_len == 0 || ike_info->ike_eklen == key_len)
				&& ike_info->ike_halg == aalg
				&& ike_info->ike_modp == group)
				{
					if (ealg_insecure)
						loglog(RC_LOG_SERIOUS, "You should NOT use insecure IKE algorithms (%s)!"
								, enum_name(&oakley_enc_names, ealg));
					return TRUE;
				}
			}
		}
		plog("Oakley Transform [%s (%d), %s, %s] refused due to %s"
				, enum_name(&oakley_enc_names, ealg), key_len
				, enum_name(&oakley_hash_names, aalg)
				, enum_name(&oakley_group_names, group)
				, ealg_insecure ?
					"insecure key_len and enc. alg. not listed in \"ike\" string" : "strict flag"
		);
		return FALSE;
	}
	return TRUE;
}