/* Copyright (c) 2016-2025 Markus Uhlin <markus@nifty-networks.net>
   All rights reserved.

   Permission to use, copy, modify, and 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 "common.h"

#ifdef UNIX
#include <sys/select.h>
#endif

#include <openssl/err.h> /* ERR_clear_error() */
#include <openssl/opensslv.h>
#include <openssl/rand.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>
#include <openssl/x509_vfy.h>

#include <limits.h>

#include "assertAPI.h"
#include "config.h"
#include "dataClassify.h"
#include "errHand.h"
#include "filePred.h"
#include "libUtils.h"
#include "main.h"
#include "nestHome.h"
#include "network.h"
#include "printtext.h"
#include "strHand.h"
#include "strdup_printf.h"
#include "tls-server.h"

#include "events/cap.h" /* get_sasl_mechanism() */

#if defined(UNIX) && defined(__STDC_NO_ATOMICS__)
#pragma message("No atomics")
#endif

STRING g_ca_file = NULL;

static SSL_CTX *ssl_ctx = NULL;
static SSL *ssl = NULL;

static volatile bool ssl_object_is_null = true;

#if defined(UNIX)
static pthread_once_t	init_done = PTHREAD_ONCE_INIT;
static pthread_mutex_t	ssl_obj_mtx;
#elif defined(WIN32)
static init_once_t	init_done = ONCE_INITIALIZER;
static HANDLE		ssl_obj_mtx;
#endif

#if OPENSSL_VERSION_NUMBER >= 0x10100000L
static void
create_ssl_context_obj(void)
{
	if ((ssl_ctx = SSL_CTX_new(TLS_client_method())) == NULL) {
		err_exit(ENOMEM, "%s: Unable to create a new SSL_CTX object",
		    __func__);
	}

	(void) SSL_CTX_set_mode(ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
	(void) SSL_CTX_set_mode(ssl_ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
	(void) SSL_CTX_set_mode(ssl_ctx, SSL_MODE_AUTO_RETRY);
	(void) SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);

	(void) SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2);
	(void) SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv3);

	if (!SSL_CTX_set_min_proto_version(ssl_ctx, TLS1_2_VERSION)) {
		err_log(0, "%s: error setting minimum supported "
		    "protocol version", __func__);
	}
}
#else
/* -------------------------------- */
/* OpenSSL version less than v1.1.0 */
/* -------------------------------- */

static void
create_ssl_context_obj_insecure(void)
{
	if ((ssl_ctx = SSL_CTX_new(SSLv23_client_method())) == NULL) {
		err_exit(ENOMEM, "%s: Unable to create a new SSL_CTX object",
		    __func__);
	}

	(void) SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2);
	(void) SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv3);
}
#endif

static STRING
get_filepath(void)
{
	if (g_home_dir == NULL || strings_match(Config("sasl_x509"), ""))
		return NULL;
	return strdup_printf("%s%s%s", g_home_dir, SLASH, Config("sasl_x509"));
}

static void
load_x509(void)
{
	CSTRING err_reason = ""; // NOLINT: dead store
	STRING file = NULL;

	if ((file = get_filepath()) == NULL) {
		err_reason = "unable to get the file path";
		goto err;
	} else if (!file_exists(file)) {
		err_reason = "file non-existent";
		goto err;
	} else if (!is_regular_file(file)) {
		err_reason = "not a regular file";
		goto err;
	} else if (SSL_use_certificate_chain_file(ssl, file) != 1) {
		err_reason = "load error";
		goto err;
	} else if (SSL_use_PrivateKey_file(ssl, file, SSL_FILETYPE_PEM) != 1) {
		err_reason = "private key error";
		goto err;
	}

	free(file);
	printtext_print("success", "%s: ok", __func__);
	return;

  err:
	free(file);
	printtext_print("err", "%s: %s", __func__, err_reason);
}

static void
set_ciphers(CSTRING list)
{
	if (ssl_ctx && list && !SSL_CTX_set_cipher_list(ssl_ctx, list)) {
		PRINTTEXT_CONTEXT ptext_ctx;
		char strerrbuf[MAXERROR] = { '\0' };

		printtext_context_init(&ptext_ctx, g_status_window,
		    TYPE_SPEC1_WARN, true);
		printtext(&ptext_ctx, "%s: bogus cipher list: %s", __func__,
		    xstrerror(EINVAL, strerrbuf, MAXERROR));
	}
}

static void
ssl_obj_mtx_init(void)
{
	mutex_new(&ssl_obj_mtx);
}

static int
verify_callback(int ok, X509_STORE_CTX *ctx)
{
	if (!ok) {
		PRINTTEXT_CONTEXT ptext_ctx;
		X509 *cert = X509_STORE_CTX_get_current_cert(ctx);
		char issuer[256]  = { '\0' };
		char subject[256] = { '\0' };
		const int depth = X509_STORE_CTX_get_error_depth(ctx);
		const int err   = X509_STORE_CTX_get_error(ctx);

		(void) X509_NAME_oneline(X509_get_issuer_name(cert), issuer,
		    sizeof issuer);
		(void) X509_NAME_oneline(X509_get_subject_name(cert), subject,
		    sizeof subject);

		printtext_context_init(&ptext_ctx, g_status_window,
		    TYPE_SPEC1_WARN, true);

		printtext(&ptext_ctx, "Error with certificate at depth: %d",
		    depth);
		printtext(&ptext_ctx, "  issuer  = %s", issuer);
		printtext(&ptext_ctx, "  subject = %s", subject);
		printtext(&ptext_ctx, "Reason: %s",
		    X509_verify_cert_error_string(err));
	}

	return ok;
}

int
net_ssl_begin(void)
{
	CSTRING			err_reason = ""; // NOLINT: dead store
	PRINTTEXT_CONTEXT	ptext_ctx;
	static const int	VALUE_HANDSHAKE_OK = 1;
	unsigned long int	err_code = 0;

	if (ssl != NULL) {
		err_reason = "SSL object nonnull";
		goto err;
	} else if ((ssl = SSL_new(ssl_ctx)) == NULL) {
		err_exit(ENOMEM, "%s: Unable to create a new SSL object",
		    __func__);
	} else {
		(void) atomic_swap_bool(&ssl_object_is_null, false);
	}

	if (sasl_is_enabled() && strings_match(get_sasl_mechanism(),
	    "EXTERNAL"))
		load_x509();

	if (!SSL_set_fd(ssl, g_socket)) {
		err_reason = "Unable to associate the global socket fd with "
		    "the SSL object";
		goto err;
	}

	SSL_set_connect_state(ssl);
	ERR_clear_error();

	if (SSL_connect(ssl) != VALUE_HANDSHAKE_OK) {
		err_reason = "TLS/SSL handshake failed!";
		goto err;
	}

	return 0;

  err:
	printtext_context_init(&ptext_ctx, g_status_window, TYPE_SPEC1_FAILURE,
	    true);
	printtext(&ptext_ctx, "%s: %s", __func__, err_reason);
	if (strings_match(err_reason, "TLS/SSL handshake failed!")) {
		err_code = ERR_peek_last_error();
		if (err_code) {
			printtext(&ptext_ctx, "%s: %s", __func__,
			    ERR_error_string(err_code, NULL));
		}
	}
	return -1;
}

void
net_ssl_end(void)
{
	mutex_lock(&ssl_obj_mtx);
	if (ssl == NULL || atomic_load_bool(&ssl_object_is_null)) {
		mutex_unlock(&ssl_obj_mtx);
		return;
	}
	if (!(SSL_get_shutdown(ssl) & SSL_SENT_SHUTDOWN)) {
		switch (SSL_shutdown(ssl)) {
		case 0:
			debug("%s: SSL_shutdown: not yet finished", __func__);
			(void) SSL_shutdown(ssl);
			break;
		case 1:
			/* success! */
			break;
		default:
			err_log(0, "%s: SSL_shutdown: error", __func__);
			break;
		}
	}
	(void) atomic_swap_bool(&ssl_object_is_null, true);
	SSL_free(ssl);
	ssl = NULL;
	mutex_unlock(&ssl_obj_mtx);
}

int
net_ssl_check_hostname(CSTRING host, unsigned int flags)
{
	X509	*cert = NULL;
	int	 ret = ERR;

	if (ssl == NULL ||
	    (cert = SSL_get_peer_certificate(ssl)) == NULL ||
	    SSL_get_verify_result(ssl) != X509_V_OK ||
	    host == NULL) {
		if (cert)
			X509_free(cert);
		return ERR;
	}

	ret = (X509_check_host(cert, host, 0, flags, NULL) > 0 ? OK : ERR);
	X509_free(cert);
	return ret;
}

SSL *
net_ssl_getobj(void)
{
	return ssl;
}

static bool
conn_is_closed(const SSL *obj)
{
	return ((SSL_get_shutdown(obj) & SSL_SENT_SHUTDOWN) ||
		(SSL_get_shutdown(obj) & SSL_RECEIVED_SHUTDOWN));
}

int
net_ssl_send(CSTRING fmt, ...)
{
	char *buf = NULL;
	char *bufptr = NULL;
	int buflen = 0;
	int n_sent = 0;
	va_list ap;

#if defined(UNIX)
	if ((errno = pthread_once(&init_done, ssl_obj_mtx_init)) != 0)
		err_sys("%s: pthread_once", __func__);
#elif defined(WIN32)
	if ((errno = init_once(&init_done, ssl_obj_mtx_init)) != 0)
		err_sys("%s: init_once", __func__);
#endif

	mutex_lock(&ssl_obj_mtx);

	if (fmt == NULL ||
	    ssl == NULL ||
	    atomic_load_bool(&ssl_object_is_null) ||
	    conn_is_closed(ssl) ||
	    g_socket == INVALID_SOCKET) {
		mutex_unlock(&ssl_obj_mtx);
		return -1;
	}

	va_start(ap, fmt);
	buf = strdup_vprintf(fmt, ap);
	va_end(ap);

	/* message terminate */
	if (!g_icb_mode)
		realloc_strcat(&buf, "\r\n");

	if (strlen(buf) > INT_MAX) {
		free(buf);
		mutex_unlock(&ssl_obj_mtx);
		return -1;
	}

	bufptr = buf;
	buflen = (int) strlen(buf);

	while (buflen > 0) {
		if (ssl == NULL ||
		    atomic_load_bool(&ssl_object_is_null) ||
		    conn_is_closed(ssl) ||
		    g_socket == INVALID_SOCKET)
			break;

		ERR_clear_error();
		const int ret = SSL_write(ssl, bufptr, buflen);

		if (ret > 0) {
			if (BIO_flush(SSL_get_wbio(ssl)) != 1)
				debug("%s: error flushing write bio", __func__);
			n_sent += ret;
			bufptr += ret;
			buflen -= ret;
		} else {
			switch (SSL_get_error(ssl, ret)) {
			case SSL_ERROR_NONE:
				sw_assert_not_reached();
				break;
			case SSL_ERROR_WANT_READ:
			case SSL_ERROR_WANT_WRITE:
				debug("%s: want read / want write", __func__);
				continue;
			}

			free(buf);
			mutex_unlock(&ssl_obj_mtx);
			return -1;
		}
	}

	free(buf);
	mutex_unlock(&ssl_obj_mtx);
	return n_sent;
}

int
net_ssl_recv(struct network_recv_context *ctx, STRING recvbuf, int recvbuf_size)
{
#ifdef UNIX
#define SOCKET_ERROR -1
#endif
	if (ctx == NULL ||
	    recvbuf == NULL ||
	    ssl == NULL ||
	    atomic_load_bool(&ssl_object_is_null) ||
	    conn_is_closed(ssl) ||
	    g_socket == INVALID_SOCKET)
		return -1;
	else if (!SSL_pending(ssl)) {
		const int	maxfdp1 = ctx->sock + 1;
		fd_set		readset;
		struct timeval	tv;

		tv.tv_sec = ctx->sec;
		tv.tv_usec = ctx->microsec;

		FD_ZERO(&readset);
		FD_SET(ctx->sock, &readset);

		errno = 0;

		if (select(maxfdp1, &readset, NULL, NULL, &tv) == SOCKET_ERROR)
			return (errno == EINTR ? 0 : -1);
		else if (!FD_ISSET(ctx->sock, &readset))
			return 0;
	}

	char	*bufptr = recvbuf;
	int	 buflen = recvbuf_size;
	int	 bytes_received = 0;

	mutex_lock(&ssl_obj_mtx);

	do {
		int ret;

		if (ssl == NULL ||
		    atomic_load_bool(&ssl_object_is_null) ||
		    conn_is_closed(ssl) ||
		    g_socket == INVALID_SOCKET) {
			mutex_unlock(&ssl_obj_mtx);
			return -1;
		}

		ERR_clear_error();

		if ((ret = SSL_read(ssl, bufptr, buflen)) > 0) {
			if (BIO_flush(SSL_get_rbio(ssl)) != 1)
				debug("%s: error flushing read bio", __func__);
			bytes_received += ret;
			bufptr += ret;
			buflen -= ret;
		} else {
			switch (SSL_get_error(ssl, ret)) {
			case SSL_ERROR_NONE:
				sw_assert_not_reached();
				break;
			case SSL_ERROR_WANT_READ:
			case SSL_ERROR_WANT_WRITE:
				debug("%s: want read / want write", __func__);
				break;
			default:
				mutex_unlock(&ssl_obj_mtx);
				return -1;
			}
		}

		UNUSED_VAR(bufptr);
		UNUSED_VAR(buflen);
	} while (false); /* buflen > 0 && SSL_pending(ssl) */

	mutex_unlock(&ssl_obj_mtx);
	return bytes_received;
}

void
net_ssl_init(void)
{
	PRINTTEXT_CONTEXT ptext_ctx;
	char strerrbuf[MAXERROR] = { '\0' };

	printtext_context_init(&ptext_ctx, g_status_window, TYPE_SPEC1_WARN,
	    true);

	SSL_load_error_strings();
	(void) SSL_library_init();

	if (RAND_load_file("/dev/urandom", 1024) <= 0) {
		printtext(&ptext_ctx, "%s: Error seeding the PRNG! (%s)",
		    __func__, xstrerror(ENOSYS, strerrbuf, MAXERROR));
	}

#if OPENSSL_VERSION_NUMBER >= 0x10100000L
	create_ssl_context_obj();
#else
#pragma message("Consider updating your TLS/SSL library")
	create_ssl_context_obj_insecure();
#endif

	if (g_ssl_verify_peer && config_bool("ssl_verify_peer", true)) {
#ifdef WIN32
		if (!SSL_CTX_load_verify_locations(ssl_ctx, g_ca_file, NULL)) {
			printtext(&ptext_ctx, "%s: Error loading CA file "
			    "and/or directory", __func__);
		}
#endif
		if (!SSL_CTX_set_default_verify_paths(ssl_ctx)) {
			printtext(&ptext_ctx, "%s: Error loading default CA "
			    "file and/or directory", __func__);
		}
		SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, verify_callback);
		SSL_CTX_set_verify_depth(ssl_ctx, 4);
	} else {
		printtext(&ptext_ctx, "%s: Certificate verification is "
		    "disabled: Option set to NO?", __func__);
	}

	CSTRING cs = Config("cipher_suite");

	if (strings_match(cs, "secure") || strings_match(cs, "SECURE"))
		set_ciphers(g_suite_secure);
	else if (strings_match(cs, "compat") || strings_match(cs, "COMPAT"))
		set_ciphers(g_suite_compat);
	else if (strings_match(cs, "legacy") || strings_match(cs, "LEGACY"))
		set_ciphers(g_suite_legacy);
	else if (strings_match(cs, "all") || strings_match(cs, "ALL") ||
		 strings_match(cs, "insecure") || strings_match(cs, "INSECURE"))
		set_ciphers(g_suite_all);
	else
		set_ciphers(g_suite_compat);

#if defined(UNIX)
	if ((errno = pthread_once(&init_done, ssl_obj_mtx_init)) != 0)
		err_sys("%s: pthread_once", __func__);
#elif defined(WIN32)
	if ((errno = init_once(&init_done, ssl_obj_mtx_init)) != 0)
		err_sys("%s: init_once", __func__);
#endif
}

void
net_ssl_deinit(void)
{
	net_ssl_end();

	if (ssl_ctx) {
		SSL_CTX_free(ssl_ctx);
		ssl_ctx = NULL;
	}

	free_and_null(&g_ca_file);
}
