/*
 * ustream-ssl - library for SSL over ustream
 *
 * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <string.h>
#include <ctype.h>
#include "ustream-ssl.h"
#include "ustream-internal.h"
#include <openssl/x509v3.h>

/* Ciphersuite preference:
 * - for server, no weak ciphers are used if you use an ECDSA key.
 * - forward-secret (pfs), authenticated (AEAD) ciphers are at the top:
 *   	chacha20-poly1305, the fastest in software, 256-bits
 * 	aes128-gcm, 128-bits
 * 	aes256-gcm, 256-bits
 * - key exchange: prefer ECDHE, then DHE (client only)
 * - forward-secret ECDSA CBC ciphers (client-only)
 * - forward-secret RSA CBC ciphers
 * - non-pfs ciphers
 *	aes128, aes256, 3DES(client only)
 */

#ifdef WOLFSSL_SSL_H
# define top_ciphers							\
				"TLS13-CHACHA20-POLY1305-SHA256:"	\
				"TLS13-AES128-GCM-SHA256:"		\
				"TLS13-AES256-GCM-SHA384:"		\
				ecdhe_aead_ciphers
#else
# define tls13_ciphersuites	"TLS_CHACHA20_POLY1305_SHA256:"		\
				"TLS_AES_128_GCM_SHA256:"		\
				"TLS_AES_256_GCM_SHA384"

# define top_ciphers							\
				ecdhe_aead_ciphers
#endif

#define ecdhe_aead_ciphers						\
				"ECDHE-ECDSA-CHACHA20-POLY1305:"	\
				"ECDHE-ECDSA-AES128-GCM-SHA256:"	\
				"ECDHE-ECDSA-AES256-GCM-SHA384:"	\
				"ECDHE-RSA-CHACHA20-POLY1305:"		\
				"ECDHE-RSA-AES128-GCM-SHA256:"		\
				"ECDHE-RSA-AES256-GCM-SHA384"

#define dhe_aead_ciphers						\
				"DHE-RSA-CHACHA20-POLY1305:"		\
				"DHE-RSA-AES128-GCM-SHA256:"		\
				"DHE-RSA-AES256-GCM-SHA384"

#define ecdhe_ecdsa_cbc_ciphers						\
				"ECDHE-ECDSA-AES128-SHA:"		\
				"ECDHE-ECDSA-AES256-SHA"

#define ecdhe_rsa_cbc_ciphers						\
				"ECDHE-RSA-AES128-SHA:"			\
				"ECDHE-RSA-AES256-SHA"

#define dhe_cbc_ciphers							\
				"DHE-RSA-AES128-SHA:"			\
				"DHE-RSA-AES256-SHA:"			\
				"DHE-DES-CBC3-SHA"

#define non_pfs_aes							\
				"AES128-GCM-SHA256:"			\
				"AES256-GCM-SHA384:"			\
				"AES128-SHA:"				\
				"AES256-SHA"

#define server_cipher_list						\
				top_ciphers ":"				\
				ecdhe_rsa_cbc_ciphers ":"		\
				non_pfs_aes

#define client_cipher_list						\
				top_ciphers ":"				\
				dhe_aead_ciphers ":"			\
				ecdhe_ecdsa_cbc_ciphers ":"		\
				ecdhe_rsa_cbc_ciphers ":"		\
				dhe_cbc_ciphers ":"			\
				non_pfs_aes ":"				\
				"DES-CBC3-SHA"

__hidden struct ustream_ssl_ctx *
__ustream_ssl_context_new(bool server)
{
	const void *m;
	SSL_CTX *c;

#if OPENSSL_VERSION_NUMBER < 0x10100000L
	static bool _init = false;

	if (!_init) {
		SSL_load_error_strings();
		SSL_library_init();
		_init = true;
	}
# ifndef TLS_server_method
#  define TLS_server_method SSLv23_server_method
# endif
# ifndef TLS_client_method
#  define TLS_client_method SSLv23_client_method
# endif
#endif

	if (server) {
		m = TLS_server_method();
	} else
		m = TLS_client_method();

	c = SSL_CTX_new((void *) m);
	if (!c)
		return NULL;

	SSL_CTX_set_verify(c, SSL_VERIFY_NONE, NULL);
	SSL_CTX_set_options(c, SSL_OP_NO_COMPRESSION | SSL_OP_SINGLE_ECDH_USE |
			       SSL_OP_CIPHER_SERVER_PREFERENCE);
#if defined(SSL_CTX_set_ecdh_auto) && OPENSSL_VERSION_NUMBER < 0x10100000L
	SSL_CTX_set_ecdh_auto(c, 1);
#elif OPENSSL_VERSION_NUMBER >= 0x10101000L
	SSL_CTX_set_ciphersuites(c, tls13_ciphersuites);
#endif
	if (server) {
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
		SSL_CTX_set_min_proto_version(c, TLS1_2_VERSION);
#else
		SSL_CTX_set_options(c, SSL_OP_NO_SSLv3 | SSL_OP_NO_TLSv1 |
				       SSL_OP_NO_TLSv1_1);
#endif
		SSL_CTX_set_cipher_list(c, server_cipher_list);
	} else {
		SSL_CTX_set_cipher_list(c, client_cipher_list);
	}
	SSL_CTX_set_quiet_shutdown(c, 1);

	return (void *) c;
}

__hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
{
	int ret;

	ret = SSL_CTX_load_verify_locations((void *) ctx, file, NULL);
	if (ret < 1)
		return -1;

	return 0;
}

__hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
{
	int ret;

	ret = SSL_CTX_use_certificate_chain_file((void *) ctx, file);
	if (ret < 1)
		ret = SSL_CTX_use_certificate_file((void *) ctx, file, SSL_FILETYPE_ASN1);

	if (ret < 1)
		return -1;

	return 0;
}

__hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
{
	int ret;

	ret = SSL_CTX_use_PrivateKey_file((void *) ctx, file, SSL_FILETYPE_PEM);
	if (ret < 1)
		ret = SSL_CTX_use_PrivateKey_file((void *) ctx, file, SSL_FILETYPE_ASN1);

	if (ret < 1)
		return -1;

	return 0;
}

__hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
{
	SSL_CTX_free((void *) ctx);
}

void __ustream_ssl_session_free(void *ssl)
{
	SSL_shutdown(ssl);
	SSL_free(ssl);
}

static void ustream_ssl_error(struct ustream_ssl *us, int ret)
{
	us->error = ret;
	uloop_timeout_set(&us->error_timer, 0);
}

#ifndef NO_X509_CHECK_HOST

static bool ustream_ssl_verify_cn(struct ustream_ssl *us, X509 *cert)
{
	int ret;

	if (!us->peer_cn)
		return false;

# ifndef WOLFSSL_OPENSSL_H_
	ret = X509_check_host(cert, us->peer_cn, 0, X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS, NULL);
# else
	ret = wolfSSL_X509_check_host(cert, us->peer_cn, 0, 0, NULL);
# endif
	return ret == 1;
}

#endif

static void ustream_ssl_verify_cert(struct ustream_ssl *us)
{
	void *ssl = us->ssl;
	X509 *cert;
	int res;

	res = SSL_get_verify_result(ssl);
	if (res != X509_V_OK) {
		if (us->notify_verify_error)
			us->notify_verify_error(us, res, X509_verify_cert_error_string(res));
		return;
	}

	cert = SSL_get_peer_certificate(ssl);
	if (!cert)
		return;

	us->valid_cert = true;
#ifndef NO_X509_CHECK_HOST
	us->valid_cn = ustream_ssl_verify_cn(us, cert);
#endif
	X509_free(cert);
}


__hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
{
	void *ssl = us->ssl;
	int r;

	ERR_clear_error();

	if (us->server)
		r = SSL_accept(ssl);
	else
		r = SSL_connect(ssl);

	if (r == 1) {
		ustream_ssl_verify_cert(us);
		return U_SSL_OK;
	}

	r = SSL_get_error(ssl, r);
	if (r == SSL_ERROR_WANT_READ || r == SSL_ERROR_WANT_WRITE)
		return U_SSL_PENDING;

	ustream_ssl_error(us, r);
	return U_SSL_ERROR;
}

__hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
{
	void *ssl = us->ssl;
	int ret;

	ERR_clear_error();

	ret = SSL_write(ssl, buf, len);

	if (ret < 0) {
		int err = SSL_get_error(ssl, ret);
		if (err == SSL_ERROR_WANT_WRITE)
			return 0;

		ustream_ssl_error(us, err);
		return -1;
	}

	return ret;
}

__hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
{
	int ret;

	ERR_clear_error();

	ret = SSL_read(us->ssl, buf, len);

	if (ret < 0) {
		ret = SSL_get_error(us->ssl, ret);
		if (ret == SSL_ERROR_WANT_READ)
			return U_SSL_PENDING;

		ustream_ssl_error(us, ret);
		return U_SSL_ERROR;
	}

	return ret;
}