/* IKE modular algorithm handling interface
 * Author: JuanJo Ciarlante <jjo-ipsec@mendoza.gov.ar>
 *
 * 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: ike_alg.c 3686 2008-03-28 11:48:14Z martin $
 */

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

#include <freeswan.h>
#include <ipsec_policy.h>

#include "constants.h"
#include "defs.h"
#include "sha1.h"
#include "md5.h"
#include "crypto.h"

#include "state.h"
#include "packet.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_encrypter(u_int alg)
{
    return (struct encrypt_desc *) ike_alg_find(IKE_ALG_ENCRYPT, alg, 0);
}

/*
 * check if IKE hash algorithm is present
 */
bool
ike_alg_hash_present(u_int halg)
{
    return ike_alg_get_hasher(halg) != NULL;
}

/*
 * check if IKE encryption algorithm is present
 */
bool
ike_alg_enc_present(u_int ealg)
{
    return ike_alg_get_encrypter(ealg) != NULL;
}

/*
 * Validate and register IKE hash algorithm object
 */
int
ike_alg_register_hash(struct hash_desc *hash_desc)
{
    const char *alg_name = NULL;
    int ret = 0;

    if (hash_desc->algo_id > OAKLEY_HASH_MAX)
    {
	plog ("ike_alg: hash alg=%d > max=%d"
		, hash_desc->algo_id, OAKLEY_HASH_MAX);
	return_on(ret,-EINVAL);
    }

    if (hash_desc->hash_ctx_size > sizeof (union hash_ctx))
    {
	plog ("ike_alg: hash alg=%d has ctx_size=%d > hash_ctx=%d"
	      , hash_desc->algo_id
	      , (int)hash_desc->hash_ctx_size
	      , (int)sizeof (union hash_ctx));
	return_on(ret,-EOVERFLOW);
    }

    if (!(hash_desc->hash_init && hash_desc->hash_update && hash_desc->hash_final))
    {
	plog ("ike_alg: hash alg=%d needs hash_init(), hash_update() and hash_final()"
	      , hash_desc->algo_id);
	return_on(ret,-EINVAL);
    }
	
    alg_name = enum_name(&oakley_hash_names, hash_desc->algo_id);
    if (!alg_name)
    {
	plog ("ike_alg: hash alg=%d not found in constants.c:oakley_hash_names"
	      , hash_desc->algo_id);
	alg_name = "<NULL>";
    }

return_out:
    if (ret == 0)
	ret = ike_alg_add((struct ike_alg *)hash_desc);

    plog("ike_alg: Activating %s hash: %s"
	,alg_name, ret == 0 ? "Ok" : "FAILED");

    return ret;
}

/*
 * Validate and register IKE encryption algorithm object
 */
int
ike_alg_register_enc(struct encrypt_desc *enc_desc)
{
    int ret = ike_alg_add((struct ike_alg *)enc_desc);

    const char *alg_name = enum_name(&oakley_enc_names, enc_desc->algo_id);

    char alg_number[20];
    
    /* algorithm is not listed in oakley_enc_names */
    if (alg_name == NULL)
    {
	snprintf(alg_number, sizeof(alg_number), "OAKLEY_ID_%d"
	    , enc_desc->algo_id);
	alg_name = alg_number;
    }

    plog("ike_alg: Activating %s encryption: %s"
	, alg_name, ret == 0 ? "Ok" : "FAILED");

    return ret;
}

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

    if ((policy & POLICY_PFS)
    && c->alg_info_esp
    && c->alg_info_esp->esp_pfsgroup)
	ret = lookup_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(struct alg_info_ike *ai , lset_t policy)
{
    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_enc_present(ealg))
	{
	    DBG_log("ike_alg: ike enc ealg=%d not present"
		    , ealg);
	    continue;
	}

	if (!ike_alg_hash_present(halg)) 
	{
	    DBG_log("ike_alg: ike hash halg=%d not present"
		    , halg);
	    continue;
	}

	enc_desc = ike_alg_get_encrypter(ealg);
	passert(enc_desc != NULL);

	if (eklen
	&& (eklen < enc_desc->keyminlen || eklen >  enc_desc->keymaxlen))
	{
	    DBG_log("ike_alg: ealg=%d (specified) keylen:%d, not valid min=%d, max=%d"
		    , ealg
		    , eklen
		    , enc_desc->keyminlen
		    , enc_desc->keymaxlen
	    );
	    continue;
	}

	if (policy & POLICY_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, OAKLEY_RSA_SIG);
	    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)
{
    u_int i;
    struct ike_alg *a;

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

    for (a = ike_alg_base[IKE_ALG_ENCRYPT]; a != NULL; a = a->algo_next)
    {
        struct encrypt_desc *desc = (struct encrypt_desc*)a;

	whack_log(RC_COMMENT, "#%-5d %s, blocksize: %d, keylen: %d-%d-%d"
	    , a->algo_id
	    , enum_name(&oakley_enc_names, a->algo_id)
	    , (int)desc->enc_blocksize*BITS_PER_BYTE
	    , desc->keyminlen
	    , desc->keydeflen
	    , desc->keymaxlen
	);
    }

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

    for (a = ike_alg_base[IKE_ALG_HASH]; a != NULL; a = a->algo_next)
    {
	whack_log(RC_COMMENT, "#%-5d %s, hashsize: %d"
	    , a->algo_id
	    , enum_name(&oakley_hash_names, a->algo_id)
	    , (int)((struct hash_desc *)a)->hash_digest_size*BITS_PER_BYTE
	);
    }

    whack_log(RC_COMMENT, " ");
    whack_log(RC_COMMENT, "List of registered IKE DH Groups:");
    whack_log(RC_COMMENT, " ");

    for (i = 0; i < elemsof(oakley_group); i++)
    {
	const struct oakley_group_desc *gdesc=oakley_group + i;

	whack_log(RC_COMMENT, "#%-5d %s, groupsize: %d"
	    , gdesc->group
	    , enum_name(&oakley_group_names, gdesc->group)
	    , (int)gdesc->bytes*BITS_PER_BYTE
	);
    }
}

/*  Show IKE algorithms for
 *    - this connection (result from ike= string)
 *    - newest SA
 */
void
ike_alg_show_connection(struct connection *c, const char *instance)
{
    char buf[256];
    struct state *st;

    if (c->alg_info_ike)
    {
	alg_info_snprint(buf, sizeof(buf)-1, (struct alg_info *)c->alg_info_ike);
	whack_log(RC_COMMENT
		, "\"%s\"%s:   IKE algorithms wanted: %s"
		, c->name
		, instance
		, buf
	);

	alg_info_snprint_ike(buf, sizeof(buf)-1, c->alg_info_ike);
	whack_log(RC_COMMENT
		, "\"%s\"%s:   IKE algorithms found:  %s"
		, c->name
		, instance
		, buf
	);
    }

    st = state_with_serialno(c->newest_isakmp_sa);
    if (st)
	whack_log(RC_COMMENT
		, "\"%s\"%s:   IKE algorithm newest: %s_%d-%s-%s"
		, c->name
		, instance
		, enum_show(&oakley_enc_names, st->st_oakley.encrypt)
		+7 /* strlen("OAKLEY_") */
		/* , st->st_oakley.encrypter->keydeflen */
		, st->st_oakley.enckeylen
		, enum_show(&oakley_hash_names, st->st_oakley.hash)
		+7 /* strlen("OAKLEY_") */
		, enum_show(&oakley_group_names, st->st_oakley.group->group)
		+13 /* strlen("OAKLEY_GROUP_") */
	);
}

/*
 * Apply a suite of testvectors to a hash algorithm
 */
static bool
ike_hash_test(const struct hash_desc *desc)
{
    bool hash_results = TRUE;
    bool hmac_results = TRUE;

    if (desc->hash_testvectors == NULL)
    {
	plog("  %s hash self-test not available", enum_name(&oakley_hash_names, desc->algo_id));
    }
    else
    {
	int i;

	for (i = 0; desc->hash_testvectors[i].msg_digest != NULL; i++)
	{
	    u_char digest[MAX_DIGEST_LEN];
	    bool result;

	    union hash_ctx ctx;

	    desc->hash_init(&ctx);
	    desc->hash_update(&ctx, desc->hash_testvectors[i].msg
				   ,desc->hash_testvectors[i].msg_size);
	    desc->hash_final(digest, &ctx);
	    result = memcmp(digest, desc->hash_testvectors[i].msg_digest
				  , desc->hash_digest_size) == 0;
	    DBG(DBG_CRYPT,
		DBG_log("  hash testvector %d: %s", i, result ? "ok":"failed")
	    )
	    hash_results &= result;
	}
	plog("  %s hash self-test %s", enum_name(&oakley_hash_names, desc->algo_id)
				, hash_results ? "passed":"failed");
    }

    if (desc->hmac_testvectors == NULL)
    {
	plog("  %s hmac self-test not available", enum_name(&oakley_hash_names, desc->algo_id));
    }
    else
    {
	int i;

	for (i = 0; desc->hmac_testvectors[i].hmac != NULL; i++)
	{
	    u_char digest[MAX_DIGEST_LEN];
	    bool result;

	    struct hmac_ctx ctx;

	    hmac_init(&ctx, desc, desc->hmac_testvectors[i].key
				, desc->hmac_testvectors[i].key_size);
	    hmac_update(&ctx, desc->hmac_testvectors[i].msg
			     ,desc->hmac_testvectors[i].msg_size);
	    hmac_final(digest, &ctx);
	    result = memcmp(digest, desc->hmac_testvectors[i].hmac
				  , desc->hash_digest_size) == 0;
	    DBG(DBG_CRYPT,
		DBG_log("  hmac testvector %d: %s", i, result ? "ok":"failed")
	    )
	    hmac_results &= result;
	}
	plog("  %s hmac self-test %s", enum_name(&oakley_hash_names, desc->algo_id)
				, hmac_results ? "passed":"failed");
    }
    return hash_results && hmac_results;
}

/*
 * Apply test vectors to registered encryption and hash algorithms
 */
bool
ike_alg_test(void)
{
    bool all_results = TRUE;
    struct ike_alg *a;

    plog("Testing registered IKE encryption algorithms:");

    for (a = ike_alg_base[IKE_ALG_ENCRYPT]; a != NULL; a = a->algo_next)
    {
	plog("  %s self-test not available", enum_name(&oakley_enc_names, a->algo_id));
    }

    plog("Testing registered IKE hash algorithms:");

    for (a = ike_alg_base[IKE_ALG_HASH]; a != NULL; a = a->algo_next)
    {
        struct hash_desc *desc = (struct hash_desc*)a;

	all_results &= ike_hash_test(desc);
    }

    if (all_results)
	plog("All crypto self-tests passed");
    else
	plog("Some crypto self-tests failed");
    return all_results;
}

/*
 * 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;
}