/************************************************************************
  *   Unreal Internet Relay Chat Daemon, src/tls.c
  *      (C) 2000 hq.alert.sk (base)
  *      (C) 2000 Carsten V. Munk <stskeeps@tspre.org> 
  *
  *   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 1, or (at your option)
  *   any later version.
  *
  *   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.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program; if not, write to the Free Software
  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
 /** @file
  * @brief TLS functions
  */
 
 #include "unrealircd.h"
 #include "openssl_hostname_validation.h"
 
 #ifdef _WIN32
 #define IDC_PASS                        1166
 extern HINSTANCE hInst;
 extern HWND hwIRCDWnd;
 #endif
 
 #define FUNC_TLS_READ 1
 #define FUNC_TLS_WRITE 2
 #define FUNC_TLS_ACCEPT 3
 #define FUNC_TLS_CONNECT 4
 
 /* Forward declarations */
 static int fatal_tls_error(int ssl_error, int where, int my_errno, Client *client);
 int cipher_check(SSL_CTX *ctx, char **errstr);
 int certificate_quality_check(SSL_CTX *ctx, char **errstr);
 
 /* The TLS structures */
 SSL_CTX *ctx_server;
 SSL_CTX *ctx_client;
 
 char *TLSKeyPasswd;
 
 typedef struct {
 	int *size;
 	char **buffer;
 } StreamIO;
 
 MODVAR int tls_client_index = 0;
 
 #ifdef _WIN32
 /** Ask private key password (Windows GUI mode only) */
 LRESULT TLS_key_passwd_dialog(HWND hDlg, UINT Message, WPARAM wParam, LPARAM lParam)
 {
 	static StreamIO *stream;
 	switch (Message) {
 		case WM_INITDIALOG:
 			stream = (StreamIO*)lParam;
 			return TRUE;
 		case WM_COMMAND:
 			if (LOWORD(wParam) == IDCANCEL) {
 				*stream->buffer = NULL;
 				EndDialog(hDlg, IDCANCEL);
 			}
 			else if (LOWORD(wParam) == IDOK) {
 				GetDlgItemText(hDlg, IDC_PASS, *stream->buffer, *stream->size);
 				EndDialog(hDlg, IDOK);
 			}
 			return FALSE;
 		case WM_CLOSE:
 			*stream->buffer = NULL;
 			EndDialog(hDlg, IDCANCEL);
 		default:
 			return FALSE;
 	}
 }
 #endif				
 
 /** Return error string for OpenSSL error.
  * @param err		OpenSSL error number to lookup
  * @param my_errno	The value of errno to use in case we want to call strerror().
  * @returns Error string, only valid until next call to this function.
  */
 const char *ssl_error_str(int err, int my_errno)
 {
 	static char ssl_errbuf[256];
 	char *ssl_errstr = NULL;
 
 	switch(err)
 	{
 		case SSL_ERROR_NONE:
 			ssl_errstr = "OpenSSL: No error";
 			break;
 		case SSL_ERROR_SSL:
 			ssl_errstr = "Internal OpenSSL error or protocol error";
 			break;
 		case SSL_ERROR_WANT_READ:
 			ssl_errstr = "OpenSSL functions requested a read()";
 			break;
 		case SSL_ERROR_WANT_WRITE:
 			ssl_errstr = "OpenSSL functions requested a write()";
 			break;
 		case SSL_ERROR_WANT_X509_LOOKUP:
 			ssl_errstr = "OpenSSL requested a X509 lookup which didn't arrive";
 			break;
 		case SSL_ERROR_SYSCALL:
 			snprintf(ssl_errbuf, sizeof(ssl_errbuf), "%s", STRERROR(my_errno));
 			ssl_errstr = ssl_errbuf;
 			break;
 		case SSL_ERROR_ZERO_RETURN:
 			ssl_errstr = "Underlying socket operation returned zero";
 			break;
 		case SSL_ERROR_WANT_CONNECT:
 			ssl_errstr = "OpenSSL functions wanted a connect()";
 			break;
 		default:
 			ssl_errstr = "Unknown OpenSSL error (huh?)";
 	}
 	return ssl_errstr;
 }
 
 /** Ask certificate private key password (rare) */
 int TLS_key_passwd_cb(char *buf, int size, int rwflag, void *password)
 {
 	char *pass;
 	static int before = 0;
 	static char beforebuf[1024];
 #ifdef _WIN32
 	StreamIO stream;
 	char passbuf[512];	
 	int passsize = 512;
 #endif
 	if (before)
 	{
 		strlcpy(buf, beforebuf, size);
 		return strlen(buf);
 	}
 #ifndef _WIN32
 	pass = getpass("Password for TLS private key: ");
 #else
 	pass = passbuf;
 	stream.buffer = &pass;
 	stream.size = &passsize;
 	DialogBoxParam(hInst, "TLSKey", hwIRCDWnd, (DLGPROC)TLS_key_passwd_dialog, (LPARAM)&stream); 
 #endif
 	if (pass)
 	{
 		strlcpy(buf, pass, size);
 		strlcpy(beforebuf, pass, sizeof(beforebuf));
 		before = 1;
 		TLSKeyPasswd = beforebuf;
 		return (strlen(buf));
 	}
 	return 0;
 }
 
 /** Verify certificate callback. */
 static int ssl_verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
 {
 	/* We accept the connection. Certificate verifiction takes
 	 * place elsewhere, such as in _verify_link().
 	 */
 	return 1;
 }
 
 /** Get Client pointer by SSL pointer */
 Client *get_client_by_ssl(SSL *ssl)
 {
 	return SSL_get_ex_data(ssl, tls_client_index);
 }
 
 /** Set requested server name as indicated by SNI */
 static void set_client_sni_name(SSL *ssl, char *name)
 {
 	Client *client = get_client_by_ssl(ssl);
 	if (client)
 		safe_strdup(client->local->sni_servername, name);
 }
 
 /** Hostname callback, used for SNI */
 static int ssl_hostname_callback(SSL *ssl, int *unk, void *arg)
 {
 	char *name = (char *)SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
 	ConfigItem_sni *sni;
 
 	if (name && (sni = find_sni(name)))
 	{
 		SSL_set_SSL_CTX(ssl, sni->ssl_ctx);
 		set_client_sni_name(ssl, name);
 	}
 
 	return SSL_TLSEXT_ERR_OK;
 }
 
 /** Disable TLS protocols as set by config */
 void disable_ssl_protocols(SSL_CTX *ctx, TLSOptions *tlsoptions)
 {
 	/* OpenSSL has three mechanisms for protocol version control... */
 
 #ifdef HAS_SSL_CTX_SET_SECURITY_LEVEL
 	/* The first one is setting a "security level" as introduced
 	 * by OpenSSL 1.1.0. Some Linux distro's like Ubuntu 20.04
 	 * seemingly compile with -DOPENSSL_TLS_SECURITY_LEVEL=2.
 	 * This means the application (UnrealIRCd) is unable to allow
 	 * TLSv1.0/1.1 even if the application is configured to do so.
 	 * So here we set the level to 1, but -again- ONLY if we are
 	 * configured to allow TLSv1.0 or v1.1, of course.
 	 */
 	if ((tlsoptions->protocols & TLS_PROTOCOL_TLSV1) ||
 	    (tlsoptions->protocols & TLS_PROTOCOL_TLSV1_1))
 	{
 		SSL_CTX_set_security_level(ctx, 0);
 	}
 #endif
 
 	/* The remaining two mechanisms are:
 	 * The old way, which is most flexible, is to use:
 	 * SSL_CTX_set_options(... SSL_OP_NO_<version>) which allows
 	 * you to disable each and every specific TLS version.
 	 *
 	 * And the new way, which only allows setting a
 	 * minimum and maximum protocol version, using:
 	 * SSL_CTX_set_min_proto_version(... <version>)
 	 * SSL_CTX_set_max_proto_version(....<version>)
 	 *
 	 * We prefer the old way, but because OpenSSL 1.0.1 and
 	 * OS's like Debian use system-wide options we are also
 	 * forced to use the new way... or at least to set a
 	 * minimum protocol version to begin with.
 	 */
 #ifdef HAS_SSL_CTX_SET_MIN_PROTO_VERSION
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1) &&
 	    !(tlsoptions->protocols & TLS_PROTOCOL_TLSV1_1))
 	{
 		SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
 	} else
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1))
 	{
 		SSL_CTX_set_min_proto_version(ctx, TLS1_1_VERSION);
 	} else
 	{
 		SSL_CTX_set_min_proto_version(ctx, TLS1_VERSION);
 	}
 #endif
 	SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2); /* always disable SSLv2 */
 	SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv3); /* always disable SSLv3 */
 
 #ifdef SSL_OP_NO_TLSv1
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1))
 		SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1);
 #endif
 
 #ifdef SSL_OP_NO_TLSv1_1
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1_1))
 		SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_1);
 #endif
 
 #ifdef SSL_OP_NO_TLSv1_2
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1_2))
 		SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_2);
 #endif
 
 #ifdef SSL_OP_NO_TLSv1_3
 	if (!(tlsoptions->protocols & TLS_PROTOCOL_TLSV1_3))
 		SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_3);
 #endif
 }
 
 /** Initialize TLS context
  * @param tlsoptions	The ::tls-options configuration
  * @param server	Set to 1 if we are initializing a server, 0 for client.
  * @returns The TLS context (SSL_CTX) or NULL in case of error.
  */
 SSL_CTX *init_ctx(TLSOptions *tlsoptions, int server)
 {
 	SSL_CTX *ctx;
 	char *errstr = NULL;
 
 	if (server)
 		ctx = SSL_CTX_new(SSLv23_server_method());
 	else
 		ctx = SSL_CTX_new(SSLv23_client_method());
 
 	if (!ctx)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_LOAD_FAILED", NULL,
 		           "Failed to do SSL_CTX_new() !?\n$tls_error.all",
 		           log_data_tls_error());
 		return NULL;
 	}
 	disable_ssl_protocols(ctx, tlsoptions);
 	SSL_CTX_set_default_passwd_cb(ctx, TLS_key_passwd_cb);
 
 	if (server && !(tlsoptions->options & TLSFLAG_DISABLECLIENTCERT))
 	{
 		/* We tell OpenSSL/LibreSSL to verify the certificate and set our callback.
 		 * Our callback will always accept the certificate since actual checking
 		 * will take place elsewhere. Why? Because certificate is (often) delayed
 		 * until after the TLS handshake. Such as in the case of link blocks where
 		 * _verify_link() will take care of it only after we learned what server
 		 * we are dealing with (and if we should verify certificates for that server).
 		 */
 		SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER|SSL_VERIFY_CLIENT_ONCE | (tlsoptions->options & TLSFLAG_FAILIFNOCERT ? SSL_VERIFY_FAIL_IF_NO_PEER_CERT : 0), ssl_verify_callback);
 	}
 	SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
 #ifndef SSL_OP_NO_TICKET
  #error "Your system has an outdated OpenSSL version. Please upgrade OpenSSL."
 #endif
 	SSL_CTX_set_options(ctx, SSL_OP_NO_TICKET);
 
 	if (SSL_CTX_use_certificate_chain_file(ctx, tlsoptions->certificate_file) <= 0)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_LOAD_FAILED", NULL,
 		           "Failed to load TLS certificate $filename\n$tls_error.all",
 		           log_data_string("filename", tlsoptions->certificate_file),
 		           log_data_tls_error());
 		goto fail;
 	}
 
 	if (SSL_CTX_use_PrivateKey_file(ctx, tlsoptions->key_file, SSL_FILETYPE_PEM) <= 0)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_LOAD_FAILED", NULL,
 		           "Failed to load TLS private key $filename\n$tls_error.all",
 		           log_data_string("filename", tlsoptions->key_file),
 		           log_data_tls_error());
 		goto fail;
 	}
 
 	if (!SSL_CTX_check_private_key(ctx))
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_LOAD_FAILED", NULL,
 		           "Check for TLS private key failed $filename\n$tls_error.all",
 		           log_data_string("filename", tlsoptions->key_file),
 		           log_data_tls_error());
 		goto fail;
 	}
 
 	if (SSL_CTX_set_cipher_list(ctx, tlsoptions->ciphers) == 0)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_INVALID_CIPHERS_LIST", NULL,
 		           "Failed to set TLS cipher list '$tls_ciphers_list'\n$tls_error.all",
 		           log_data_string("tls_ciphers_list", tlsoptions->ciphers),
 		           log_data_tls_error());
 		goto fail;
 	}
 
 #ifdef SSL_OP_NO_TLSv1_3
 	if (SSL_CTX_set_ciphersuites(ctx, tlsoptions->ciphersuites) == 0)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_INVALID_CIPHERSUITES_LIST", NULL,
 		           "Failed to set TLS ciphersuites list '$tls_ciphersuites_list'\n$tls_error.all",
 		           log_data_string("tls_ciphersuites_list", tlsoptions->ciphersuites),
 		           log_data_tls_error());
 		goto fail;
 	}
 #endif
 
 	if (!cipher_check(ctx, &errstr))
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_CIPHER_CHECK_FAILED", NULL,
 		           "There is a problem with your TLS 'ciphers' configuration setting: $quality_check_error\n"
 		           "Remove the ciphers setting from your configuration file to use safer defaults, or change the cipher setting.",
 		           log_data_string("quality_check_error", errstr));
 		goto fail;
 	}
 
 	if (!certificate_quality_check(ctx, &errstr))
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_CERTIFICATE_CHECK_FAILED", NULL,
 		           "There is a problem with your TLS certificate '$filename': $quality_check_error\n"
 		           "If you use the standard UnrealIRCd certificates then you can simply run 'make pem' and 'make install' "
 		           "from your UnrealIRCd source directory (eg: ~/unrealircd-6.X.Y/) to create and install new certificates",
 		           log_data_string("filename", tlsoptions->certificate_file),
 		           log_data_string("quality_check_error", errstr));
 		goto fail;
 	}
 
 	if (server)
 		SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
 
 	if (tlsoptions->trusted_ca_file)
 	{
 		if (!SSL_CTX_load_verify_locations(ctx, tlsoptions->trusted_ca_file, NULL))
 		{
 			unreal_log(ULOG_ERROR, "config", "TLS_LOAD_FAILED", NULL,
 				   "Failed to load trusted-ca-file $filename\n$tls_error.all",
 				   log_data_string("filename", tlsoptions->trusted_ca_file),
 				   log_data_tls_error());
 			goto fail;
 		}
 	}
 
 	if (server)
 	{
 #if defined(SSL_CTX_set_ecdh_auto)
 		/* OpenSSL 1.0.x requires us to explicitly turn this on */
 		SSL_CTX_set_ecdh_auto(ctx, 1);
 #elif OPENSSL_VERSION_NUMBER < 0x10100000L
 		/* Even older versions require require setting a fixed curve.
 		 * NOTE: Don't be confused by the <1.1.x check.
 		 * Yes, it must be there. Do not remove it!
 		 */
 		SSL_CTX_set_tmp_ecdh(ctx, EC_KEY_new_by_curve_name(NID_X9_62_prime256v1));
 #else
 		/* If we end up here we don't have SSL_CTX_set_ecdh_auto
 		 * and we are on OpenSSL 1.1.0 or later. We don't need to
 		 * do anything then, since auto ecdh is the default.
 		 */
 #endif
 		/* Let's see if we need to (and can) set specific curves */
 		if (tlsoptions->ecdh_curves)
 		{
 #ifdef HAS_SSL_CTX_SET1_CURVES_LIST
 			if (!SSL_CTX_set1_curves_list(ctx, tlsoptions->ecdh_curves))
 			{
 				unreal_log(ULOG_ERROR, "config", "TLS_INVALID_ECDH_CURVES_LIST", NULL,
 					   "Failed to set ecdh-curves '$ecdh_curves_list'\n$tls_error.all\n"
 					   "HINT: o get a list of supported curves with the appropriate names, "
 					   "run 'openssl ecparam -list_curves' on the server. "
 					   "Separate multiple curves by colon, for example: "
 					   "ecdh-curves \"secp521r1:secp384r1\".",
 					   log_data_string("ecdh_curves_list", tlsoptions->ecdh_curves),
 					   log_data_tls_error());
 				goto fail;
 			}
 #else
 			/* We try to avoid this in the config code, but better have
 			 * it here too than be sorry if someone screws up:
 			 */
 			unreal_log(ULOG_ERROR, "config", "BUG_ECDH_CURVES", NULL,
 			           "ecdh-curves specified but not supported by library -- BAD!");
 			goto fail;
 #endif
 		}
 		/* We really want the ECDHE/ECDHE to be generated per-session.
 		 * Added in 2015 for safety. Seems OpenSSL was smart enough
 		 * to make this the default in 2016 after a security advisory.
 		 */
 		SSL_CTX_set_options(ctx, SSL_OP_SINGLE_ECDH_USE|SSL_OP_SINGLE_DH_USE);
 	}
 
 	if (server)
 	{
 		SSL_CTX_set_tlsext_servername_callback(ctx, ssl_hostname_callback);
 	}
 
 	return ctx;
 fail:
 	SSL_CTX_free(ctx);
 	return NULL;
 }
 
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
 MODVAR EVP_MD *sha256_function; /**< SHA256 function for EVP_DigestInit_ex() call */
 MODVAR EVP_MD *sha1_function; /**< SHA1 function for EVP_DigestInit_ex() call */
 MODVAR EVP_MD *md5_function; /**< MD5 function for EVP_DigestInit_ex() call */
 #endif
 
 /** Early initalization of TLS subsystem - called on startup */
 int early_init_tls(void)
 {
 	SSL_load_error_strings();
 	SSLeay_add_ssl_algorithms();
 
 	/* This is used to track (SSL *) <--> (Client *) relationships: */
 	tls_client_index = SSL_get_ex_new_index(0, "tls_client", NULL, NULL, NULL);
 
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
 	sha256_function = EVP_MD_fetch(NULL, "SHA2-256", NULL);
 	if (!sha256_function)
 	{
 		fprintf(stderr, "Could not find SHA256 algorithm in TLS library\n");
 		exit(6);
 	}
 
 	sha1_function = EVP_MD_fetch(NULL, "SHA1", NULL);
 	if (!sha1_function)
 	{
 		fprintf(stderr, "Could not find SHA1 algorithm in TLS library\n");
 		exit(6);
 	}
 
 	md5_function = EVP_MD_fetch(NULL, "MD5", NULL);
 	if (!md5_function)
 	{
 		fprintf(stderr, "Could not find MD5 algorithm in TLS library\n");
 		exit(6);
 	}
 #endif
 	return 1;
 }
 
 /** Initialize the server and client contexts.
  * This is only possible after reading the configuration file.
  */
 int init_tls(void)
 {
 	ctx_server = init_ctx(iConf.tls_options, 1);
 	if (!ctx_server)
 		return 0;
 	ctx_client = init_ctx(iConf.tls_options, 0);
 	if (!ctx_client)
 		return 0;
 	return 1;
 }
 
 /** Reinitialize TLS server and client contexts - after REHASH -tls
  */
 int reinit_tls(void)
 {
 	SSL_CTX *tmp;
 	ConfigItem_listen *listen;
 	ConfigItem_sni *sni;
 	ConfigItem_link *link;
 
 	tmp = init_ctx(iConf.tls_options, 1);
 	if (!tmp)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_RELOAD_FAILED", NULL,
 		           "TLS Reload failed. See previous errors.");
 		return 0;
 	}
 	if (ctx_server)
 		SSL_CTX_free(ctx_server);
 	ctx_server = tmp; /* activate */
 	
 	tmp = init_ctx(iConf.tls_options, 0);
 	if (!tmp)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_RELOAD_FAILED", NULL,
 		           "TLS Reload failed at client context. See previous errors.");
 		return 0;
 	}
 	if (ctx_client)
 		SSL_CTX_free(ctx_client);
 	ctx_client = tmp; /* activate */
 
 	/* listen::tls-options.... */
 	for (listen = conf_listen; listen; listen = listen->next)
 	{
 		if (listen->tls_options)
 		{
 			tmp = init_ctx(listen->tls_options, 1);
 			if (!tmp)
 			{
 				unreal_log(ULOG_ERROR, "config", "TLS_RELOAD_FAILED", NULL,
 					   "TLS Reload failed at listen::tls-options. See previous errors.");
 				return 0;
 			}
 			if (listen->ssl_ctx)
 				SSL_CTX_free(listen->ssl_ctx);
 			listen->ssl_ctx = tmp; /* activate */
 		}
 	}
 
 	/* sni::tls-options.... */
 	for (sni = conf_sni; sni; sni = sni->next)
 	{
 		if (sni->tls_options)
 		{
 			tmp = init_ctx(sni->tls_options, 1);
 			if (!tmp)
 			{
 				unreal_log(ULOG_ERROR, "config", "TLS_RELOAD_FAILED", NULL,
 					   "TLS Reload failed at sni::tls-options. See previous errors.");
 				return 0;
 			}
 			if (sni->ssl_ctx)
 				SSL_CTX_free(sni->ssl_ctx);
 			sni->ssl_ctx = tmp; /* activate */
 		}
 	}
 
 	/* link::outgoing::tls-options.... */
 	for (link = conf_link; link; link = link->next)
 	{
 		if (link->tls_options)
 		{
 			tmp = init_ctx(link->tls_options, 0);
 			if (!tmp)
 			{
 				unreal_log(ULOG_ERROR, "config", "TLS_RELOAD_FAILED", NULL,
 					   "TLS Reload failed at link $servername due to outgoing::tls-options. See previous errors.",
 					   log_data_string("servername", link->servername));
 				return 0;
 			}
 			if (link->ssl_ctx)
 				SSL_CTX_free(link->ssl_ctx);
 			link->ssl_ctx = tmp; /* activate */
 		}
 	}
 
 	return 1;
 }
 
 /** Set SSL connection as nonblocking */
 void SSL_set_nonblocking(SSL *s)
 {
 	BIO_set_nbio(SSL_get_rbio(s),1);
 	BIO_set_nbio(SSL_get_wbio(s),1);
 }
 
 /** Get TLS ciphersuite */
 const char *tls_get_cipher(Client *client)
 {
 	static char buf[256];
 	const char *cached;
 
 	cached = moddata_client_get(client, "tls_cipher");
 	if (cached)
 		return cached;
 
 	if (!MyConnect(client) || !client->local->ssl)
 		return NULL;
 
 	buf[0] = '\0';
 	strlcpy(buf, SSL_get_version(client->local->ssl), sizeof(buf));
 	strlcat(buf, "-", sizeof(buf));
 	strlcat(buf, SSL_get_cipher(client->local->ssl), sizeof(buf));
 
 	return buf;
 }
 
 /** Get the applicable ::tls-options block for this local client,
  * which may be defined in the link block, listen block, or set block.
  */
 TLSOptions *get_tls_options_for_client(Client *client)
 {
 	if (!client->local)
 		return NULL;
 	if (client->server && client->server->conf && client->server->conf->tls_options)
 		return client->server->conf->tls_options;
 	if (client->local && client->local->listener && client->local->listener->tls_options)
 		return client->local->listener->tls_options;
 	return iConf.tls_options;
 }
 
 /** Outgoing TLS connect (read: handshake) to another server. */
 void unreal_tls_client_handshake(int fd, int revents, void *data)
 {
 	Client *client = data;
 	SSL_CTX *ctx = (client->server && client->server->conf && client->server->conf->ssl_ctx) ? client->server->conf->ssl_ctx : ctx_client;
 	TLSOptions *tlsoptions = get_tls_options_for_client(client);
 
 	if (!ctx)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_CREATE_SESSION_FAILED", NULL,
 		           "Could not start TLS client handshake (no ctx?): TLS was possibly not loaded correctly on this server!?\n$tls_error.all",
 		           log_data_tls_error());
 		return;
 	}
 
 	client->local->ssl = SSL_new(ctx);
 	if (!client->local->ssl)
 	{
 		unreal_log(ULOG_ERROR, "config", "TLS_CREATE_SESSION_FAILED", NULL,
 		           "Could not start TLS client handshake: TLS was possibly not loaded correctly on this server!?\n$tls_error.all",
 		           log_data_tls_error());
 		return;
 	}
 
 	SSL_set_fd(client->local->ssl, client->local->fd);
 	SSL_set_connect_state(client->local->ssl);
 	SSL_set_nonblocking(client->local->ssl);
 
 	if (tlsoptions->renegotiate_bytes > 0)
 	{
 		BIO_set_ssl_renegotiate_bytes(SSL_get_rbio(client->local->ssl), tlsoptions->renegotiate_bytes);
 		BIO_set_ssl_renegotiate_bytes(SSL_get_wbio(client->local->ssl), tlsoptions->renegotiate_bytes);
 	}
 
 	if (tlsoptions->renegotiate_timeout > 0)
 	{
 		BIO_set_ssl_renegotiate_timeout(SSL_get_rbio(client->local->ssl), tlsoptions->renegotiate_timeout);
 		BIO_set_ssl_renegotiate_timeout(SSL_get_wbio(client->local->ssl), tlsoptions->renegotiate_timeout);
 	}
 
 	if (client->server && client->server->conf)
 	{
 		/* Client: set hostname for SNI */
 		SSL_set_tlsext_host_name(client->local->ssl, client->server->conf->servername);
 	}
 
 	SetTLS(client);
 
 	switch (unreal_tls_connect(client, fd))
 	{
 		case -1:
 			SSL_set_shutdown(client->local->ssl, SSL_RECEIVED_SHUTDOWN);
 			SSL_smart_shutdown(client->local->ssl);
 			SSL_free(client->local->ssl);
 			client->local->ssl = NULL;
 			ClearTLS(client);
 			SetDeadSocket(client);
 			fd_close(fd);
 			fd_unnotify(fd);
 			client->local->fd = -1;
 			--OpenFiles;
 			return;
 		case 0: 
 			SetTLSConnectHandshake(client);
 			return;
 		case 1:
 			return;
 		default:
 			return;
 	}
 
 }
 
 /** Called by I/O engine to (re)try accepting an TLS connection */
 static void unreal_tls_accept_retry(int fd, int revents, void *data)
 {
 	Client *client = data;
 	unreal_tls_accept(client, fd);
 }
 
 /** Accept an TLS connection - that is: do the TLS handshake */
 int unreal_tls_accept(Client *client, int fd)
 {
 	int ssl_err;
 
 #ifdef MSG_PEEK
 	if (!IsNextCall(client))
 	{
 		char buf[1024];
 		int n;
 		
 		n = recv(fd, buf, sizeof(buf), MSG_PEEK);
 		if ((n >= 8) && !strncmp(buf, "STARTTLS", 8))
 		{
 			char buf[512];
 			snprintf(buf, sizeof(buf),
 				"ERROR :STARTTLS received but this is a TLS-only port. Check your connect settings. "
 				"If this is a server linking in then add 'tls' in your link::outgoing::options block.\r\n");
 			(void)send(fd, buf, strlen(buf), 0);
 			return fatal_tls_error(SSL_ERROR_SSL, FUNC_TLS_ACCEPT, ERRNO, client);
 		}
 		if ((n >= 4) && (!strncmp(buf, "USER", 4) || !strncmp(buf, "NICK", 4) || !strncmp(buf, "PASS", 4) || !strncmp(buf, "CAP ", 4)))
 		{
 			char buf[512];
 			snprintf(buf, sizeof(buf),
 				"ERROR :NON-TLS command received on TLS-only port. Check your connection settings.\r\n");
 			(void)send(fd, buf, strlen(buf), 0);
 			return fatal_tls_error(SSL_ERROR_SSL, FUNC_TLS_ACCEPT, ERRNO, client);
 		}
 		if ((n >= 8) && (!strncmp(buf, "PROTOCTL", 8) || !strncmp(buf, "SERVER", 6)))
 		{
 			char buf[512];
 			snprintf(buf, sizeof(buf),
 				"ERROR :NON-TLS command received on TLS-only port. Check your connection settings.\r\n");
 			(void)send(fd, buf, strlen(buf), 0);
 			return fatal_tls_error(SSL_ERROR_SSL, FUNC_TLS_ACCEPT, ERRNO, client);
 		}
 		if (n > 0)
 			SetNextCall(client);
 	}
 #endif
 	if ((ssl_err = SSL_accept(client->local->ssl)) <= 0)
 	{
 		switch (ssl_err = SSL_get_error(client->local->ssl, ssl_err))
 		{
 			case SSL_ERROR_SYSCALL:
 				if (ERRNO == P_EINTR || ERRNO == P_EWOULDBLOCK || ERRNO == P_EAGAIN)
 				{
 					return 1;
 				}
 				return fatal_tls_error(ssl_err, FUNC_TLS_ACCEPT, ERRNO, client);
 			case SSL_ERROR_WANT_READ:
 				fd_setselect(fd, FD_SELECT_READ, unreal_tls_accept_retry, client);
 				fd_setselect(fd, FD_SELECT_WRITE, NULL, client);
 				return 1;
 			case SSL_ERROR_WANT_WRITE:
 				fd_setselect(fd, FD_SELECT_READ, NULL, client);
 				fd_setselect(fd, FD_SELECT_WRITE, unreal_tls_accept_retry, client);
 				return 1;
 			default:
 				return fatal_tls_error(ssl_err, FUNC_TLS_ACCEPT, ERRNO, client);
 		}
 		/* NOTREACHED */
 		return -1;
 	}
 
 	client->local->listener->start_handshake(client);
 
 	return 1;
 }
 
 /** Called by the I/O engine to (re)try to connect to a remote host */
 static void unreal_tls_connect_retry(int fd, int revents, void *data)
 {
 	Client *client = data;
 	unreal_tls_connect(client, fd);
 }
 
 /** Connect to a remote host - that is: connect and do the TLS handshake */
 int unreal_tls_connect(Client *client, int fd)
 {
 	int ssl_err;
 
 	if ((ssl_err = SSL_connect(client->local->ssl)) <= 0)
 	{
 		ssl_err = SSL_get_error(client->local->ssl, ssl_err);
 		switch(ssl_err)
 		{
 			case SSL_ERROR_SYSCALL:
 				if (ERRNO == P_EINTR || ERRNO == P_EWOULDBLOCK || ERRNO == P_EAGAIN)
 				{
 					/* Hmmm. This implementation is different than in unreal_tls_accept().
 					 * One of them must be wrong -- better check! (TODO)
 					 */
 					fd_setselect(fd, FD_SELECT_READ|FD_SELECT_WRITE, unreal_tls_connect_retry, client);
 					return 0;
 				}
 				return fatal_tls_error(ssl_err, FUNC_TLS_CONNECT, ERRNO, client);
 			case SSL_ERROR_WANT_READ:
 				fd_setselect(fd, FD_SELECT_READ, unreal_tls_connect_retry, client);
 				fd_setselect(fd, FD_SELECT_WRITE, NULL, client);
 				return 0;
 			case SSL_ERROR_WANT_WRITE:
 				fd_setselect(fd, FD_SELECT_READ, NULL, client);
 				fd_setselect(fd, FD_SELECT_WRITE, unreal_tls_connect_retry, client);
 				return 0;
 			default:
 				return fatal_tls_error(ssl_err, FUNC_TLS_CONNECT, ERRNO, client);
 		}
 		/* NOTREACHED */
 		return -1;
 	}
 
 	fd_setselect(fd, FD_SELECT_READ | FD_SELECT_WRITE, NULL, client);
 	completed_connection(fd, FD_SELECT_READ | FD_SELECT_WRITE, client);
 
 	return 1;
 }
 
 /** Shutdown a TLS connection (gracefully) */
 int SSL_smart_shutdown(SSL *ssl)
 {
 	char i;
 	int rc = 0;
 
 	for(i = 0; i < 4; i++)
 	{
 		if ((rc = SSL_shutdown(ssl)))
 			break;
 	}
 	return rc;
 }
 
 /**
  * Report a fatal TLS error and disconnect the associated client.
  *
  * @param ssl_error The error as from OpenSSL.
  * @param where The location, one of the SAFE_SSL_* defines.
  * @param my_errno A preserved value of errno to pass to ssl_error_str().
  * @param client The client the error is associated with.
  */
 static int fatal_tls_error(int ssl_error, int where, int my_errno, Client *client)
 {
 	/* don`t alter ERRNO */
 	int errtmp = ERRNO;
 	const char *ssl_errstr, *ssl_func;
 	unsigned long additional_errno = ERR_get_error();
 	char additional_info[256];
 	char buf[512];
 	const char *one, *two;
 
 	if (IsDeadSocket(client))
 		return -1;
 
 	switch(where)
 	{
 		case FUNC_TLS_READ:
 			ssl_func = "SSL_read()";
 			break;
 		case FUNC_TLS_WRITE:
 			ssl_func = "SSL_write()";
 			break;
 		case FUNC_TLS_ACCEPT:
 			ssl_func = "SSL_accept()";
 			break;
 		case FUNC_TLS_CONNECT:
 			ssl_func = "SSL_connect()";
 			break;
 		default:
 			ssl_func = "undefined SSL func";
 	}
 
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
 	/* Fetch additional error information from OpenSSL 3.0.0+ */
 	two = ERR_reason_error_string(additional_errno);
 	if (two && *two)
 	{
 		snprintf(additional_info, sizeof(additional_info), ": %s", two);
 	} else {
 		*additional_info = '\0';
 	}
 #else
 	/* Fetch additional error information from OpenSSL. This is new as of Nov 2017 (4.0.16+) */
 	one = ERR_func_error_string(additional_errno);
 	two = ERR_reason_error_string(additional_errno);
 	if (one && *one && two && *two)
 	{
 		snprintf(additional_info, sizeof(additional_info), ": %s: %s", one, two);
 	} else {
 		*additional_info = '\0';
 	}
 #endif
 
 	ssl_errstr = ssl_error_str(ssl_error, my_errno);
 
 	SetDeadSocket(client);
 	unreal_log(ULOG_DEBUG, "tls", "DEBUG_TLS_FATAL_ERROR", client,
 		   "Exiting TLS client $client.details: $tls_function: $tls_error_string: $tls_additional_info",
 		   log_data_string("tls_function", ssl_func),
 		   log_data_string("tls_error_string", ssl_errstr),
 		   log_data_string("tls_additional_info", additional_info));
 
 	if (where == FUNC_TLS_CONNECT)
 	{
 		char extra[256];
 		*extra = '\0';
 		if (ssl_error == SSL_ERROR_SSL)
 		{
 			snprintf(extra, sizeof(extra),
 			         ". Please verify that listen::options::ssl is enabled on port %d in %s's configuration file.",
 			         (client->server && client->server->conf) ? client->server->conf->outgoing.port : -1,
 			         client->name);
 		}
 		snprintf(buf, sizeof(buf), "%s: %s%s%s", ssl_func, ssl_errstr, additional_info, extra);
 		lost_server_link(client, buf);
 	} else
 	if (IsServer(client) || (client->server && client->server->conf))
 	{
 		/* Either a trusted fully established server (incoming) or an outgoing server link (established or not) */
 		snprintf(buf, sizeof(buf), "%s: %s%s", ssl_func, ssl_errstr, additional_info);
 		lost_server_link(client, buf);
 	}
 
 	if (errtmp)
 	{
 		SET_ERRNO(errtmp);
 		safe_strdup(client->local->error_str, strerror(errtmp));
 	} else {
 		SET_ERRNO(P_EIO);
 		safe_strdup(client->local->error_str, ssl_errstr);
 	}
 
 	/* deregister I/O notification since we don't care anymore. the actual closing of socket will happen later. */
 	if (client->local->fd >= 0)
 		fd_unnotify(client->local->fd);
 
 	return -1;
 }
 
 /** Do a TLS handshake after a STARTTLS, as a client */
 int client_starttls(Client *client)
 {
 	if ((client->local->ssl = SSL_new(ctx_client)) == NULL)
 		goto fail_starttls;
 
 	SetTLS(client);
 
 	SSL_set_fd(client->local->ssl, client->local->fd);
 	SSL_set_nonblocking(client->local->ssl);
 
 	if (client->server && client->server->conf)
 	{
 		/* Client: set hostname for SNI */
 		SSL_set_tlsext_host_name(client->local->ssl, client->server->conf->servername);
 	}
 
 	if (unreal_tls_connect(client, client->local->fd) < 0)
 	{
 		SSL_set_shutdown(client->local->ssl, SSL_RECEIVED_SHUTDOWN);
 		SSL_smart_shutdown(client->local->ssl);
 		SSL_free(client->local->ssl);
 		goto fail_starttls;
 	}
 
 	/* HANDSHAKE IN PROGRESS */
 	return 0;
 fail_starttls:
 	/* Failure */
 	sendnumeric(client, ERR_STARTTLS, "STARTTLS failed");
 	client->local->ssl = NULL;
 	ClearTLS(client);
 	SetUnknown(client);
 	return 0; /* hm. we allow to continue anyway. not sure if we want that. */
 }
 
 /** Find the appropriate TLSOptions structure for a client.
  * NOTE: The default global TLS options will be returned if not found,
  *       or NULL if no such options are available (unlikely, but possible?).
  */
 TLSOptions *FindTLSOptionsForUser(Client *client)
 {
 	ConfigItem_sni *sni;
 	TLSOptions *sslopt = iConf.tls_options; /* default */
 	
 	if (!MyConnect(client) || !IsSecure(client))
 		return NULL;
 
 	/* Different sts-policy depending on SNI: */
 	if (client->local->sni_servername)
 	{
 		sni = find_sni(client->local->sni_servername);
 		if (sni)
 		{
 			sslopt = sni->tls_options;
 		}
 		/* It is perfectly possible that 'name' is not found and 'sni' is NULL,
 		 * if a client used a hostname which we do not know about (eg: 'dummy').
 		 */
 	}
 
 	return sslopt;
 }
 
 /** Verify certificate and make sure the certificate is valid for 'hostname'.
  * @param ssl: The SSL structure of the client or server
  * @param hostname: The hostname we should expect the certificate to be valid for
  * @param errstr: Error will be stored in here (optional)
  * @returns Returns 1 on success and 0 on error.
  */
 int verify_certificate(SSL *ssl, const char *hostname, char **errstr)
 {
 	static char buf[512];
 	X509 *cert;
 	int n;
 
 	*buf = '\0';
 
 	if (errstr)
 		*errstr = NULL; /* default */
 
 	if (!ssl)
 	{
 		strlcpy(buf, "Not using TLS", sizeof(buf));
 		if (errstr)
 			*errstr = buf;
 		return 0; /* Cannot verify a non-TLS connection */
 	}
 
 	if (SSL_get_verify_result(ssl) != X509_V_OK)
 	{
 		// FIXME: there are actually about 25+ different possible errors,
 		// this is only the most common one:
 		strlcpy(buf, "Certificate is not issued by a trusted Certificate Authority", sizeof(buf));
 		if (errstr)
 			*errstr = buf;
 		return 0; /* Certificate verify failed */
 	}
 
 	/* Now verify if the name of the certificate matches hostname */
 	cert = SSL_get_peer_certificate(ssl);
 
 	if (!cert)
 	{
 		strlcpy(buf, "No certificate provided", sizeof(buf));
 		if (errstr)
 			*errstr = buf;
 		return 0;
 	}
 
 #ifdef HAS_X509_check_host
 	n = X509_check_host(cert, hostname, strlen(hostname), 0, NULL);
 	X509_free(cert);
 	if (n == 1)
 		return 1; /* Hostname matched. All tests passed. */
 #else
 	/* Fallback code for OpenSSL <1.0.2.
 	 * Wait... 1.0.1 is out of support since January 2017,
 	 * so why do we even support that in 2023 ?
 	 * An well, TODO: ditch this old TLS support in next major UnrealIRCd
 	 * along with all the other old OpenSSL checks in this tls.c :D
 	 * XXX: Actually our HAS_X509_check_host includes openssl/x509v3.h
 	 * which does not exist in 1.0.2 yet either (it is openssl/x509.h there).
 	 * And 1.0.2 is out of support since January 1st, 2020... just saying.
 	 */
 	n = validate_hostname(hostname, cert);
 	X509_free(cert);
 	if (n == MatchFound)
 		return 1; /* Hostname matched. All tests passed. */
 #endif
 
 	/* Certificate is verified but is issued for a different hostname */
 	snprintf(buf, sizeof(buf), "Certificate '%s' is not valid for hostname '%s'",
 		certificate_name(ssl), hostname);
 	if (errstr)
 		*errstr = buf;
 	return 0;
 }
 
 /** Grab the certificate name */
 const char *certificate_name(SSL *ssl)
 {
 	static char buf[384];
 	X509 *cert;
 	X509_NAME *n;
 
 	if (!ssl)
 		return NULL;
 
 	cert = SSL_get_peer_certificate(ssl);
 	if (!cert)
 		return NULL;
 
 	n = X509_get_subject_name(cert);
 	if (n)
 	{
 		buf[0] = '\0';
 		X509_NAME_oneline(n, buf, sizeof(buf));
 		X509_free(cert);
 		return buf;
 	} else {
 		X509_free(cert);
 		return NULL;
 	}
 }
 
 /** Check if any weak ciphers are in use */
 int cipher_check(SSL_CTX *ctx, char **errstr)
 {
 	SSL *ssl;
 	static char errbuf[256];
 	int i;
 	const char *cipher;
 
 	*errbuf = '\0'; // safety
 
 	if (errstr)
 		*errstr = errbuf;
 
 	/* there isn't an SSL_CTX_get_cipher_list() unfortunately. */
 	ssl = SSL_new(ctx);
 	if (!ssl)
 	{
 		snprintf(errbuf, sizeof(errbuf), "Could not create TLS structure");
 		return 0;
 	}
 
 	/* Very weak */
 	i = 0;
 	while ((cipher = SSL_get_cipher_list(ssl, i++)))
 	{
 		if (strstr(cipher, "DES-"))
 		{
 			snprintf(errbuf, sizeof(errbuf), "DES is enabled but is a weak cipher");
 			SSL_free(ssl);
 			return 0;
 		}
 		else if (strstr(cipher, "3DES-"))
 		{
 			snprintf(errbuf, sizeof(errbuf), "3DES is enabled but is a weak cipher");
 			SSL_free(ssl);
 			return 0;
 		}
 		else if (strstr(cipher, "RC4-"))
 		{
 			snprintf(errbuf, sizeof(errbuf), "RC4 is enabled but is a weak cipher");
 			SSL_free(ssl);
 			return 0;
 		}
 		else if (strstr(cipher, "NULL-"))
 		{
 			snprintf(errbuf, sizeof(errbuf), "NULL cipher provides no encryption");
 			SSL_free(ssl);
 			return 0;
 		}
 	}
 
 	SSL_free(ssl);
 	return 1;
 }
 
 /** Check if a certificate (or actually: key) is weak */
 int certificate_quality_check(SSL_CTX *ctx, char **errstr)
 {
 #if OPENSSL_VERSION_NUMBER < 0x30000000L
 	// FIXME: this only works on OpenSSL <3.0.0
 	SSL *ssl;
 	X509 *cert;
 	EVP_PKEY *public_key;
 	RSA *rsa_key;
 	int key_length;
 	static char errbuf[256];
 
 	*errbuf = '\0'; // safety
 
 	if (errstr)
 		*errstr = errbuf;
 
 	/* there isn't an SSL_CTX_get_cipher_list() unfortunately. */
 	ssl = SSL_new(ctx);
 	if (!ssl)
 	{
 		snprintf(errbuf, sizeof(errbuf), "Could not create TLS structure");
 		return 0;
 	}
 
 	cert = SSL_get_certificate(ssl);
 	if (!cert)
 	{
 		snprintf(errbuf, sizeof(errbuf), "Could not retrieve TLS certificate");
 		SSL_free(ssl);
 		return 0;
 	}
 
 	public_key = X509_get_pubkey(cert);
 	if (!public_key)
 	{
 		/* Now this is unexpected.. */
 		config_warn("certificate_quality_check(): could not check public key !? BUG?");
 		SSL_free(ssl);
 		return 1;
 	}
 	rsa_key = EVP_PKEY_get1_RSA(public_key);
 	if (!rsa_key)
 	{
 		/* Not an RSA key, then we are done. */
 		EVP_PKEY_free(public_key);
 		SSL_free(ssl);
 		return 1;
 	}
 	key_length = RSA_size(rsa_key) * 8;
 
 	EVP_PKEY_free(public_key);
 	RSA_free(rsa_key);
 	SSL_free(ssl);
 
 	if (key_length < 2048)
 	{
 		snprintf(errbuf, sizeof(errbuf), "Your TLS certificate key is only %d bits, which is insecure", key_length);
 		return 0;
 	}
 
 #endif
 	return 1;
 }
 
 const char *spki_fingerprint_ex(X509 *x509_cert);
 
 /** Return the SPKI Fingerprint for a client.
  *
  * This is basically the same output as
  * openssl x509 -noout -in certificate.pem -pubkey | openssl asn1parse -noout -inform pem -out public.key
  * openssl dgst -sha256 -binary public.key | openssl enc -base64
  * ( from https://tools.ietf.org/html/draft-ietf-websec-key-pinning-21#appendix-A )
  */
 const char *spki_fingerprint(Client *cptr)
 {
 	X509 *x509_cert = NULL;
 	const char *ret;
 
 	if (!MyConnect(cptr) || !cptr->local->ssl)
 		return NULL;
 
 	x509_cert = SSL_get_peer_certificate(cptr->local->ssl);
 	if (!x509_cert)
 		return NULL;
 	ret = spki_fingerprint_ex(x509_cert);
 	X509_free(x509_cert);
 	return ret;
 }
 
 const char *spki_fingerprint_ex(X509 *x509_cert)
 {
 	unsigned char *der_cert = NULL, *p;
 	int der_cert_len, n;
 	static char retbuf[256];
 	unsigned char checksum[SHA256_DIGEST_LENGTH];
 
 	memset(retbuf, 0, sizeof(retbuf));
 
 	der_cert_len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(x509_cert), NULL);
 	if ((der_cert_len > 0) && (der_cert_len < 16384))
 	{
 		der_cert = p = safe_alloc(der_cert_len);
 		n = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(x509_cert), &p);
 
 		if ((n > 0) && ((p - der_cert) == der_cert_len))
 		{
 			/* The DER encoded SPKI is stored in 'der_cert' with length 'der_cert_len'.
 			 * Now we need to create an SHA256 hash out of it.
 			 */
 			sha256hash_binary(checksum, der_cert, der_cert_len);
 
 			/* And convert the binary to a base64 string... */
 			n = b64_encode(checksum, SHA256_DIGEST_LENGTH, retbuf, sizeof(retbuf));
 			safe_free(der_cert);
 			return retbuf; /* SUCCESS */
 		}
 		safe_free(der_cert);
 	}
 	return NULL;
 }
 
 /** Returns 1 if the client is using an outdated protocol or cipher, 0 otherwise */
 int outdated_tls_client(Client *client)
 {
 	TLSOptions *tlsoptions = get_tls_options_for_client(client);
 	char buf[1024], *name, *p;
 	const char *client_protocol = SSL_get_version(client->local->ssl);
 	const char *client_ciphersuite = SSL_get_cipher(client->local->ssl);
 
 	if (!tlsoptions)
 		return 0; /* odd.. */
 
 	strlcpy(buf, tlsoptions->outdated_protocols, sizeof(buf));
 	for (name = strtoken(&p, buf, ","); name; name = strtoken(&p, NULL, ","))
 	{
 		if (match_simple(name, client_protocol))
 			 return 1; /* outdated protocol */
 	}
 
 	strlcpy(buf, tlsoptions->outdated_ciphers, sizeof(buf));
 	for (name = strtoken(&p, buf, ","); name; name = strtoken(&p, NULL, ","))
 	{
 		if (match_simple(name, client_ciphersuite))
 			return 1; /* outdated cipher */
 	}
 
 	return 0; /* OK, not outdated */
 }
 
 /** Returns the expanded string used for set::outdated-tls-policy::user-message etc. */
 const char *outdated_tls_client_build_string(const char *pattern, Client *client)
 {
 	static char buf[512];
 	const char *name[3], *value[3];
 	const char *str;
 
 	str = SSL_get_version(client->local->ssl);
 	name[0] = "protocol";
 	value[0] = str ? str : "???";
 
 	str = SSL_get_cipher(client->local->ssl);
 	name[1] = "cipher";
 	value[1] = str ? str : "???";
 
 	name[2] = value[2] = NULL;
 
 	buildvarstring(pattern, buf, sizeof(buf), name, value);
 	return buf;
 }
 
 int check_certificate_expiry_ctx(SSL_CTX *ctx, char **errstr)
 {
 #if !defined(HAS_ASN1_TIME_diff) || !defined(HAS_X509_get0_notAfter)
 	return 0;
 #else
 	static char errbuf[512];
 	SSL *ssl;
 	X509 *cert;
 	const ASN1_TIME *cert_expiry_time;
 	int days_expiry = 0, seconds_expiry = 0;
 	long duration;
 
 	*errstr = NULL;
 
 	ssl = SSL_new(ctx);
 	if (!ssl)
 		return 0;
 
 	cert = SSL_get_certificate(ssl);
 	if (!cert)
 	{
 		SSL_free(ssl);
 		return 0;
 	}
 
 	/* get certificate time */
 	cert_expiry_time = X509_get0_notAfter(cert);
 
 	/* calculate difference */
 	ASN1_TIME_diff(&days_expiry, &seconds_expiry, cert_expiry_time, NULL);
 	duration = (days_expiry * 86400) + seconds_expiry;
 
 	/* certificate expiry? */
 	if ((days_expiry > 0) || (seconds_expiry > 0))
 	{
 		snprintf(errbuf, sizeof(errbuf), "certificate expired %s ago", pretty_time_val(duration));
 		SSL_free(ssl);
 		*errstr = errbuf;
 		return 1;
 	} else
 	/* or near-expiry? */
 	if (((days_expiry < 0) || (seconds_expiry < 0)) && (days_expiry > -7))
 	{
 		snprintf(errbuf, sizeof(errbuf), "certificate will expire in %s", pretty_time_val(0 - duration));
 		SSL_free(ssl);
 		*errstr = errbuf;
 		return 1;
 	}
 
 	/* All good */
 	SSL_free(ssl);
 	return 0;
 #endif
 }
 
 void check_certificate_expiry_tlsoptions_and_warn(TLSOptions *tlsoptions)
 {
 	SSL_CTX *ctx;
 	int ret;
 	char *errstr = NULL;
 
 	ctx = init_ctx(tlsoptions, 1);
 	if (!ctx)
 		return;
 
 	if (check_certificate_expiry_ctx(ctx, &errstr))
 	{
 		unreal_log(ULOG_ERROR, "tls", "TLS_CERT_EXPIRING", NULL,
 		           "Warning: TLS certificate '$filename': $error_string",
 		           log_data_string("filename", tlsoptions->certificate_file),
 		           log_data_string("error_string", errstr));
 	}
 	SSL_CTX_free(ctx);
 }
 
 EVENT(tls_check_expiry)
 {
 	ConfigItem_listen *listen;
 	ConfigItem_sni *sni;
 	ConfigItem_link *link;
 
 	/* set block */
 	check_certificate_expiry_tlsoptions_and_warn(iConf.tls_options);
 
 	for (listen = conf_listen; listen; listen = listen->next)
 		if (listen->tls_options)
 			check_certificate_expiry_tlsoptions_and_warn(listen->tls_options);
 
 	/* sni::tls-options.... */
 	for (sni = conf_sni; sni; sni = sni->next)
 		if (sni->tls_options)
 			check_certificate_expiry_tlsoptions_and_warn(sni->tls_options);
 
 	/* link::outgoing::tls-options.... */
 	for (link = conf_link; link; link = link->next)
 		if (link->tls_options)
 			check_certificate_expiry_tlsoptions_and_warn(link->tls_options);
 }

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