/*

 * Copyright (C) 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 <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include "errors.h"

#include <libtasn1.h>

#include <global.h>

#include <num.h>		/* MAX */

#include <tls-sig.h>

#include "str.h"

#include <datum.h>

#include "x509_int.h"

#include <nettle/base64.h>

#include <common.h>

#include <gnutls/abstract.h>

#include <system.h>

#include <locks.h>

struct gnutls_tdb_int {

	gnutls_tdb_store_func store;

	gnutls_tdb_store_commitment_func cstore;

	gnutls_tdb_verify_func verify;

};

static int raw_pubkey_to_base64(const gnutls_datum_t * raw,

				gnutls_datum_t * b64);

static int verify_pubkey(const char *file, const char *host,

			 const char *service, const gnutls_datum_t * skey);

static

int store_commitment(const char *db_name, const char *host,

		     const char *service, time_t expiration,

		     gnutls_digest_algorithm_t hash_algo,

		     const gnutls_datum_t * hash);

static

int store_pubkey(const char *db_name, const char *host,

		 const char *service, time_t expiration,

		 const gnutls_datum_t * pubkey);

static int find_config_file(char *file, size_t max_size);

extern void *_gnutls_file_mutex;

struct gnutls_tdb_int default_tdb = {

	store_pubkey,

	store_commitment,

	verify_pubkey

};

/**

 * gnutls_verify_stored_pubkey:

 * @db_name: A file specifying the stored keys (use NULL for the default)

 * @tdb: A storage structure or NULL to use the default

 * @host: The peer's name

 * @service: non-NULL if this key is specific to a service (e.g. http)

 * @cert_type: The type of the certificate

 * @cert: The raw (der) data of the certificate

 * @flags: should be 0.

 *

 * This function will try to verify a raw public-key or a public-key provided via

 * a raw (DER-encoded) certificate using a list of stored public keys.

 * The @service field if non-NULL should be a port number.

 *

 * The @db_name variable if non-null specifies a custom backend for

 * the retrieval of entries. If it is NULL then the

 * default file backend will be used. In POSIX-like systems the

 * file backend uses the $HOME/.gnutls/known_hosts file.

 *

 * Note that if the custom storage backend is provided the

 * retrieval function should return %GNUTLS_E_CERTIFICATE_KEY_MISMATCH

 * if the host/service pair is found but key doesn't match,

 * %GNUTLS_E_NO_CERTIFICATE_FOUND if no such host/service with

 * the given key is found, and 0 if it was found. The storage

 * function should return 0 on success.

 *

 * As of GnuTLS 3.6.6 this function also verifies raw public keys.

 *

 * Returns: If no associated public key is found

 * then %GNUTLS_E_NO_CERTIFICATE_FOUND will be returned. If a key

 * is found but does not match %GNUTLS_E_CERTIFICATE_KEY_MISMATCH

 * is returned. On success, %GNUTLS_E_SUCCESS (0) is returned,

 * or a negative error value on other errors.

 *

 * Since: 3.0.13

 **/

int

gnutls_verify_stored_pubkey(const char *db_name,

			    gnutls_tdb_t tdb,

			    const char *host,

			    const char *service,

			    gnutls_certificate_type_t cert_type,

			    const gnutls_datum_t * cert,

			    unsigned int flags)

{

	gnutls_datum_t pubkey = { NULL, 0 }; // Holds the pubkey in subjectPublicKeyInfo format (DER encoded)

	int ret;

	char local_file[MAX_FILENAME];

	bool need_free;

	if (db_name == NULL && tdb == NULL) {

		ret = find_config_file(local_file, sizeof(local_file));

		if (ret < 0)

			return gnutls_assert_val(ret);

		db_name = local_file;

	}

	if (tdb == NULL)

		tdb = &default_tdb;

	/* Import the public key depending on the provided certificate type */

	switch (cert_type) {

		case GNUTLS_CRT_X509:

			/* Extract the pubkey from the cert. This function does a malloc

			 * deep down the call chain. We are responsible for freeing. */

			ret = _gnutls_x509_raw_crt_to_raw_pubkey(cert, &pubkey);

			if (ret < 0) {

				_gnutls_free_datum(&pubkey);

				return gnutls_assert_val(ret);

			}

			need_free = true;

			break;

		case GNUTLS_CRT_RAWPK:

			pubkey.data = cert->data;

			pubkey.size = cert->size;

			need_free = false;

			break;

		default:

			return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE);

	}

	// Verify our pubkey against the database

	ret = tdb->verify(db_name, host, service, &pubkey);

	if (ret < 0 && ret != GNUTLS_E_CERTIFICATE_KEY_MISMATCH)

		ret = gnutls_assert_val(GNUTLS_E_NO_CERTIFICATE_FOUND);

	if (need_free) {

		_gnutls_free_datum(&pubkey);

	}

	return ret;

}

static int parse_commitment_line(char *line,

				 const char *host, size_t host_len,

				 const char *service, size_t service_len,

				 time_t now, const gnutls_datum_t * skey)

{

	char *p, *kp;

	char *savep = NULL;

	size_t kp_len, phash_size;

	time_t expiration;

	int ret;

	const mac_entry_st *hash_algo;

	uint8_t phash[MAX_HASH_SIZE];

	uint8_t hphash[MAX_HASH_SIZE * 2 + 1];

	/* read host */

	p = strtok_r(line, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	if (p[0] != '*' && host != NULL && strcmp(p, host) != 0)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read service */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	if (p[0] != '*' && service != NULL && strcmp(p, service) != 0)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read expiration */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	expiration = (time_t) atol(p);

	if (expiration > 0 && now > expiration)

		return gnutls_assert_val(GNUTLS_E_EXPIRED);

	/* read hash algorithm */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	hash_algo = mac_to_entry(atol(p));

	if (_gnutls_digest_get_name(hash_algo) == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read hash */

	kp = strtok_r(NULL, "|", &savep);

	if (kp == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	p = strpbrk(kp, "\n \r\t|");

	if (p != NULL)

		*p = 0;

	/* hash and hex encode */

	ret =

	    _gnutls_hash_fast((gnutls_digest_algorithm_t)hash_algo->id,

				skey->data, skey->size, phash);

	if (ret < 0)

		return gnutls_assert_val(ret);

	phash_size = _gnutls_hash_get_algo_len(hash_algo);

	p = _gnutls_bin2hex(phash, phash_size, (void *) hphash,

			    sizeof(hphash), NULL);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

	kp_len = strlen(kp);

	if (kp_len != phash_size * 2)

		return

		    gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH);

	if (memcmp(kp, hphash, kp_len) != 0)

		return

		    gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH);

	/* key found and matches */

	return 0;

}

static int parse_line(char *line,

		      const char *host, size_t host_len,

		      const char *service, size_t service_len,

		      time_t now,

		      const gnutls_datum_t * rawkey,

		      const gnutls_datum_t * b64key)

{

	char *p, *kp;

	char *savep = NULL;

	size_t kp_len;

	time_t expiration;

	/* read version */

	p = strtok_r(line, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	if (strncmp(p, "c0", 2) == 0)

		return parse_commitment_line(p + 3, host, host_len,

					     service, service_len, now,

					     rawkey);

	if (strncmp(p, "g0", 2) != 0)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read host */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	if (p[0] != '*' && host != NULL && strcmp(p, host) != 0)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read service */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	if (p[0] != '*' && service != NULL && strcmp(p, service) != 0)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	/* read expiration */

	p = strtok_r(NULL, "|", &savep);

	if (p == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	expiration = (time_t) atol(p);

	if (expiration > 0 && now > expiration)

		return gnutls_assert_val(GNUTLS_E_EXPIRED);

	/* read key */

	kp = strtok_r(NULL, "|", &savep);

	if (kp == NULL)

		return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);

	p = strpbrk(kp, "\n \r\t|");

	if (p != NULL)

		*p = 0;

	kp_len = strlen(kp);

	if (kp_len != b64key->size)

		return

		    gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH);

	if (memcmp(kp, b64key->data, b64key->size) != 0)

		return

		    gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH);

	/* key found and matches */

	return 0;

}

/* Returns the base64 key if found

 */

static int verify_pubkey(const char *file,

			 const char *host, const char *service,

			 const gnutls_datum_t * pubkey)

{

	FILE *fp;

	char *line = NULL;

	size_t line_size = 0;

	int ret, l2, mismatch = 0;

	size_t host_len = 0, service_len = 0;

	time_t now = gnutls_time(0);

	gnutls_datum_t b64key = { NULL, 0 };

	ret = raw_pubkey_to_base64(pubkey, &b64key);

	if (ret < 0)

		return gnutls_assert_val(ret);

	if (host != NULL)

		host_len = strlen(host);

	if (service != NULL)

		service_len = strlen(service);

	fp = fopen(file, "rbe");

	if (fp == NULL) {

		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);

		goto cleanup;

	}

	do {

		l2 = getline(&line, &line_size, fp);

		if (l2 > 0) {

			ret =

			    parse_line(line, host, host_len, service,

				       service_len, now, pubkey, &b64key);

			if (ret == 0) {	/* found */

				goto cleanup;

			} else if (ret ==

				   GNUTLS_E_CERTIFICATE_KEY_MISMATCH)

				mismatch = 1;

		}

	}

	while (l2 >= 0);

	if (mismatch)

		ret = GNUTLS_E_CERTIFICATE_KEY_MISMATCH;

	else

		ret = GNUTLS_E_NO_CERTIFICATE_FOUND;

      cleanup:

	free(line);

	if (fp != NULL)

		fclose(fp);

	gnutls_free(b64key.data);

	return ret;

}

static int raw_pubkey_to_base64(const gnutls_datum_t * raw,

				gnutls_datum_t * b64)

{

	size_t size;

	size = BASE64_ENCODE_RAW_LENGTH(raw->size);

	b64->data = gnutls_malloc(size);

	if (b64->data == NULL)

		return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

	base64_encode_raw((void*)b64->data, raw->size, raw->data);

	b64->size = size;

	return 0;

}

static

int store_pubkey(const char *db_name, const char *host,

		 const char *service, time_t expiration,

		 const gnutls_datum_t * pubkey)

{

	FILE *fp = NULL;

	gnutls_datum_t b64key = { NULL, 0 };

	int ret;

	ret = gnutls_mutex_lock(&_gnutls_file_mutex);

	if (ret != 0)

		return gnutls_assert_val(GNUTLS_E_LOCKING_ERROR);

	ret = raw_pubkey_to_base64(pubkey, &b64key);

	if (ret < 0) {

		gnutls_assert();

		goto cleanup;

	}

	fp = fopen(db_name, "abe+");

	if (fp == NULL) {

		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);

		goto cleanup;

	}

	if (service == NULL)

		service = "*";

	if (host == NULL)

		host = "*";

	fprintf(fp, "|g0|%s|%s|%lu|%.*s\n", host, service,

		(unsigned long) expiration, b64key.size, b64key.data);

	ret = 0;

      cleanup:

	if (fp != NULL)

		fclose(fp);

	gnutls_mutex_unlock(&_gnutls_file_mutex);

	gnutls_free(b64key.data);

	return ret;

}

static

int store_commitment(const char *db_name, const char *host,

		     const char *service, time_t expiration,

		     gnutls_digest_algorithm_t hash_algo,

		     const gnutls_datum_t * hash)

{

	FILE *fp;

	char buffer[MAX_HASH_SIZE * 2 + 1];

	fp = fopen(db_name, "abe+");

	if (fp == NULL)

		return gnutls_assert_val(GNUTLS_E_FILE_ERROR);

	if (service == NULL)

		service = "*";

	if (host == NULL)

		host = "*";

	fprintf(fp, "|c0|%s|%s|%lu|%u|%s\n", host, service,

		(unsigned long) expiration, (unsigned) hash_algo,

		_gnutls_bin2hex(hash->data, hash->size, buffer,

				sizeof(buffer), NULL));

	fclose(fp);

	return 0;

}

/**

 * gnutls_store_pubkey:

 * @db_name: A file specifying the stored keys (use NULL for the default)

 * @tdb: A storage structure or NULL to use the default

 * @host: The peer's name

 * @service: non-NULL if this key is specific to a service (e.g. http)

 * @cert_type: The type of the certificate

 * @cert: The data of the certificate

 * @expiration: The expiration time (use 0 to disable expiration)

 * @flags: should be 0.

 *

 * This function will store a raw public-key or a public-key provided via

 * a raw (DER-encoded) certificate to the list of stored public keys. The key

 * will be considered valid until the provided expiration time.

 *

 * The @tdb variable if non-null specifies a custom backend for

 * the storage of entries. If it is NULL then the

 * default file backend will be used.

 *

 * Unless an alternative @tdb is provided, the storage format is a textual format

 * consisting of a line for each host with fields separated by '|'. The contents of

 * the fields are a format-identifier which is set to 'g0', the hostname that the

 * rest of the data applies to, the numeric port or host name, the expiration

 * time in seconds since the epoch (0 for no expiration), and a base64

 * encoding of the raw (DER) public key information (SPKI) of the peer.

 *

 * As of GnuTLS 3.6.6 this function also accepts raw public keys.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a

 *   negative error value.

 *

 * Since: 3.0.13

 **/

int

gnutls_store_pubkey(const char *db_name,

		    gnutls_tdb_t tdb,

		    const char *host,

		    const char *service,

		    gnutls_certificate_type_t cert_type,

		    const gnutls_datum_t * cert,

		    time_t expiration, unsigned int flags)

{

	gnutls_datum_t pubkey = { NULL, 0 }; // Holds the pubkey in subjectPublicKeyInfo format (DER encoded)

	int ret;

	char local_file[MAX_FILENAME];

	bool need_free;

	if (db_name == NULL && tdb == NULL) {

		ret =

		    _gnutls_find_config_path(local_file,

					     sizeof(local_file));

		if (ret < 0)

			return gnutls_assert_val(ret);

		_gnutls_debug_log("Configuration path: %s\n", local_file);

		mkdir(local_file, 0700);

		ret = find_config_file(local_file, sizeof(local_file));

		if (ret < 0)

			return gnutls_assert_val(ret);

		db_name = local_file;

	}

	if (tdb == NULL)

		tdb = &default_tdb;

	/* Import the public key depending on the provided certificate type */

	switch (cert_type) {

		case GNUTLS_CRT_X509:

			/* Extract the pubkey from the cert. This function does a malloc

			 * deep down the call chain. We are responsible for freeing. */

			ret = _gnutls_x509_raw_crt_to_raw_pubkey(cert, &pubkey);

			if (ret < 0) {

				_gnutls_free_datum(&pubkey);

				return gnutls_assert_val(ret);

			}

			need_free = true;

			break;

		case GNUTLS_CRT_RAWPK:

			pubkey.data = cert->data;

			pubkey.size = cert->size;

			need_free = false;

			break;

		default:

			return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE);

	}

	_gnutls_debug_log("Configuration file: %s\n", db_name);

	tdb->store(db_name, host, service, expiration, &pubkey);

	if (need_free) {

		_gnutls_free_datum(&pubkey);

	}

	return GNUTLS_E_SUCCESS;

}

/**

 * gnutls_store_commitment:

 * @db_name: A file specifying the stored keys (use NULL for the default)

 * @tdb: A storage structure or NULL to use the default

 * @host: The peer's name

 * @service: non-NULL if this key is specific to a service (e.g. http)

 * @hash_algo: The hash algorithm type

 * @hash: The raw hash

 * @expiration: The expiration time (use 0 to disable expiration)

 * @flags: should be 0 or %GNUTLS_SCOMMIT_FLAG_ALLOW_BROKEN.

 *

 * This function will store the provided hash commitment to

 * the list of stored public keys. The key with the given

 * hash will be considered valid until the provided expiration time.

 *

 * The @tdb variable if non-null specifies a custom backend for

 * the storage of entries. If it is NULL then the

 * default file backend will be used.

 *

 * Note that this function is not thread safe with the default backend.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a

 *   negative error value.

 *

 * Since: 3.0

 **/

int

gnutls_store_commitment(const char *db_name,

			gnutls_tdb_t tdb,

			const char *host,

			const char *service,

			gnutls_digest_algorithm_t hash_algo,

			const gnutls_datum_t * hash,

			time_t expiration, unsigned int flags)

{

	int ret;

	char local_file[MAX_FILENAME];

	const mac_entry_st *me = hash_to_entry(hash_algo);

	if (me == NULL)

		return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);

	if (!(flags & GNUTLS_SCOMMIT_FLAG_ALLOW_BROKEN) && _gnutls_digest_is_secure(me) == 0)

		return gnutls_assert_val(GNUTLS_E_INSUFFICIENT_SECURITY);

	if (_gnutls_hash_get_algo_len(me) != hash->size)

		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	if (db_name == NULL && tdb == NULL) {

		ret =

		    _gnutls_find_config_path(local_file,

					     sizeof(local_file));

		if (ret < 0)

			return gnutls_assert_val(ret);

		_gnutls_debug_log("Configuration path: %s\n", local_file);

		mkdir(local_file, 0700);

		ret = find_config_file(local_file, sizeof(local_file));

		if (ret < 0)

			return gnutls_assert_val(ret);

		db_name = local_file;

	}

	if (tdb == NULL)

		tdb = &default_tdb;

	_gnutls_debug_log("Configuration file: %s\n", db_name);

	tdb->cstore(db_name, host, service, expiration,

		(gnutls_digest_algorithm_t)me->id, hash);

	return 0;

}

#define CONFIG_FILE "known_hosts"

static int find_config_file(char *file, size_t max_size)

{

	char path[MAX_FILENAME];

	int ret;

	ret = _gnutls_find_config_path(path, sizeof(path));

	if (ret < 0)

		return gnutls_assert_val(ret);

	if (path[0] == 0)

		snprintf(file, max_size, "%s", CONFIG_FILE);

	else

		snprintf(file, max_size, "%s/%s", path, CONFIG_FILE);

	return 0;

}

/**

 * gnutls_tdb_init:

 * @tdb: A pointer to the type to be initialized

 *

 * This function will initialize a public key trust storage structure.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a

 *   negative error value.

 **/

int gnutls_tdb_init(gnutls_tdb_t * tdb)

{

	*tdb = gnutls_calloc(1, sizeof(struct gnutls_tdb_int));

	if (!*tdb)

		return GNUTLS_E_MEMORY_ERROR;

	return 0;

}

/**

 * gnutls_set_store_func:

 * @tdb: The trust storage

 * @store: The storage function

 *

 * This function will associate a storage function with the

 * trust storage structure. The function is of the following form.

 *

 * int gnutls_tdb_store_func(const char* db_name, const char* host,

 *		       const char* service, time_t expiration,

 *		       const gnutls_datum_t* pubkey);

 *

 * The @db_name should be used to pass any private data to this function.

 *

 **/

void gnutls_tdb_set_store_func(gnutls_tdb_t tdb,

			       gnutls_tdb_store_func store)

{

	tdb->store = store;

}

/**

 * gnutls_set_store_commitment_func:

 * @tdb: The trust storage

 * @cstore: The commitment storage function

 *

 * This function will associate a commitment (hash) storage function with the

 * trust storage structure. The function is of the following form.

 *

 * int gnutls_tdb_store_commitment_func(const char* db_name, const char* host,

 *		       const char* service, time_t expiration,

 *		       gnutls_digest_algorithm_t, const gnutls_datum_t* hash);

 *

 * The @db_name should be used to pass any private data to this function.

 *

 **/

void gnutls_tdb_set_store_commitment_func(gnutls_tdb_t tdb,

					  gnutls_tdb_store_commitment_func

					  cstore)

{

	tdb->cstore = cstore;

}

/**

 * gnutls_set_verify_func:

 * @tdb: The trust storage

 * @verify: The verification function

 *

 * This function will associate a retrieval function with the

 * trust storage structure. The function is of the following form.

 *

 * int gnutls_tdb_verify_func(const char* db_name, const char* host,

 *		      const char* service, const gnutls_datum_t* pubkey);

 *

 * The verify function should return zero on a match, %GNUTLS_E_CERTIFICATE_KEY_MISMATCH

 * if there is a mismatch and any other negative error code otherwise.

 *

 * The @db_name should be used to pass any private data to this function.

 *

 **/

void gnutls_tdb_set_verify_func(gnutls_tdb_t tdb,

				gnutls_tdb_verify_func verify)

{

	tdb->verify = verify;

}

/**

 * gnutls_tdb_deinit:

 * @tdb: The structure to be deinitialized

 *

 * This function will deinitialize a public key trust storage structure.

 **/

void gnutls_tdb_deinit(gnutls_tdb_t tdb)

{

	gnutls_free(tdb);

}