/*

 * Copyright (C) 2001-2012 Free Software Foundation, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include <ext/srp.h>

#ifdef ENABLE_SRP

#include "auth.h"

#include <auth/srp_kx.h>

#include "errors.h"

#include "algorithms.h"

#include <num.h>

#include <extensions.h>

static int _gnutls_srp_unpack(gnutls_buffer_st * ps,

			      gnutls_ext_priv_data_t * _priv);

static int _gnutls_srp_pack(gnutls_ext_priv_data_t epriv,

			    gnutls_buffer_st * ps);

static void _gnutls_srp_deinit_data(gnutls_ext_priv_data_t epriv);

static int _gnutls_srp_recv_params(gnutls_session_t state,

				   const uint8_t * data, size_t data_size);

static int _gnutls_srp_send_params(gnutls_session_t state,

				   gnutls_buffer_st * extdata);

const extension_entry_st ext_mod_srp = {

	.name = "SRP",

	.type = GNUTLS_EXTENSION_SRP,

	.parse_type = GNUTLS_EXT_TLS,

	.recv_func = _gnutls_srp_recv_params,

	.send_func = _gnutls_srp_send_params,

	.pack_func = _gnutls_srp_pack,

	.unpack_func = _gnutls_srp_unpack,

	.deinit_func = _gnutls_srp_deinit_data,

	.cannot_be_overriden = 1

};

static int

_gnutls_srp_recv_params(gnutls_session_t session, const uint8_t * data,

			size_t _data_size)

{

	uint8_t len;

	ssize_t data_size = _data_size;

	gnutls_ext_priv_data_t epriv;

	srp_ext_st *priv;

	if (session->security_parameters.entity == GNUTLS_SERVER) {

		if (data_size > 0) {

			DECR_LEN(data_size, 1);

			len = data[0];

			DECR_LEN(data_size, len);

			if (MAX_USERNAME_SIZE < len) {

				gnutls_assert();

				return GNUTLS_E_ILLEGAL_SRP_USERNAME;

			}

			priv = gnutls_calloc(1, sizeof(*priv));

			if (priv == NULL) {

				gnutls_assert();

				return GNUTLS_E_MEMORY_ERROR;

			}

			priv->username = gnutls_malloc(len + 1);

			if (priv->username) {

				memcpy(priv->username, &data[1], len);

				/* null terminated */

				priv->username[len] = 0;

			}

			epriv = priv;

			_gnutls_ext_set_session_data(session,

						     GNUTLS_EXTENSION_SRP,

						     epriv);

		}

	}

	return 0;

}

static unsigned have_srp_ciphersuites(gnutls_session_t session)

{

	unsigned j;

	unsigned kx;

	for (j = 0; j < session->internals.priorities->cs.size; j++) {

		kx = session->internals.priorities->cs.entry[j]->kx_algorithm;

		if (kx == GNUTLS_KX_SRP || kx == GNUTLS_KX_SRP_RSA || kx == GNUTLS_KX_SRP_DSS)

			return 1;

	}

	return 0;

}

/* returns data_size or a negative number on failure

 * data is allocated locally

 */

static int

_gnutls_srp_send_params(gnutls_session_t session,

			gnutls_buffer_st * extdata)

{

	unsigned len;

	int ret;

	gnutls_ext_priv_data_t epriv;

	srp_ext_st *priv = NULL;

	char *username = NULL, *password = NULL;

	gnutls_srp_client_credentials_t cred =

		    (gnutls_srp_client_credentials_t)

		    _gnutls_get_cred(session, GNUTLS_CRD_SRP);

	if (session->security_parameters.entity != GNUTLS_CLIENT)

		return 0;

	if (cred == NULL)

		return 0;

	if (!have_srp_ciphersuites(session)) {

		return 0;

	}

	/* this function sends the client extension data (username) */

	priv = gnutls_calloc(1, sizeof(*priv));

	if (priv == NULL)

		return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

	if (cred->username != NULL) {	/* send username */

		len = MIN(strlen(cred->username), 255);

		ret =

		    _gnutls_buffer_append_data_prefix(extdata, 8,

						      cred->

						      username,

						      len);

		if (ret < 0) {

			gnutls_assert();

			goto cleanup;

		}

		priv->username = strdup(cred->username);

		if (priv->username == NULL) {

			gnutls_assert();

			goto cleanup;

		}

		priv->password = strdup(cred->password);

		if (priv->password == NULL) {

			gnutls_assert();

			goto cleanup;

		}

		epriv = priv;

		_gnutls_ext_set_session_data(session,

					     GNUTLS_EXTENSION_SRP,

					     epriv);

		return len + 1;

	} else if (cred->get_function != NULL) {

		/* Try the callback

		 */

		if (cred->

		    get_function(session, &username, &password) < 0

		    || username == NULL || password == NULL) {

			gnutls_assert();

			return GNUTLS_E_ILLEGAL_SRP_USERNAME;

		}

		len = MIN(strlen(username), 255);

		priv->username = username;

		priv->password = password;

		ret =

		    _gnutls_buffer_append_data_prefix(extdata, 8,

						      username,

						      len);

		if (ret < 0) {

			ret = gnutls_assert_val(ret);

			goto cleanup;

		}

		epriv = priv;

		_gnutls_ext_set_session_data(session,

					     GNUTLS_EXTENSION_SRP,

					     epriv);

		return len + 1;

	}

	return 0;

      cleanup:

	gnutls_free(username);

	gnutls_free(password);

	gnutls_free(priv);

	return ret;

}

static void _gnutls_srp_deinit_data(gnutls_ext_priv_data_t epriv)

{

	srp_ext_st *priv = epriv;

	gnutls_free(priv->username);

	gnutls_free(priv->password);

	gnutls_free(priv);

}

static int

_gnutls_srp_pack(gnutls_ext_priv_data_t epriv, gnutls_buffer_st * ps)

{

	srp_ext_st *priv = epriv;

	int ret;

	int password_len = 0, username_len = 0;

	if (priv->username)

		username_len = strlen(priv->username);

	if (priv->password)

		password_len = strlen(priv->password);

	BUFFER_APPEND_PFX4(ps, priv->username, username_len);

	BUFFER_APPEND_PFX4(ps, priv->password, password_len);

	return 0;

}

static int

_gnutls_srp_unpack(gnutls_buffer_st * ps, gnutls_ext_priv_data_t * _priv)

{

	srp_ext_st *priv;

	int ret;

	gnutls_ext_priv_data_t epriv;

	gnutls_datum_t username = { NULL, 0 };

	gnutls_datum_t password = { NULL, 0 };

	priv = gnutls_calloc(1, sizeof(*priv));

	if (priv == NULL) {

		gnutls_assert();

		return GNUTLS_E_MEMORY_ERROR;

	}

	BUFFER_POP_DATUM(ps, &username);

	BUFFER_POP_DATUM(ps, &password);

	priv->username = (char *) username.data;

	priv->password = (char *) password.data;

	epriv = priv;

	*_priv = epriv;

	return 0;

      error:

	_gnutls_free_datum(&username);

	_gnutls_free_datum(&password);

	return ret;

}

#endif				/* ENABLE_SRP */