/*
* SSL/TLS interface definition
* Copyright (c) 2004-2013, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#ifndef TLS_H
#define TLS_H
struct tls_connection;
struct tls_random {
const u8 *client_random;
size_t client_random_len;
const u8 *server_random;
size_t server_random_len;
};
enum tls_event {
TLS_CERT_CHAIN_SUCCESS,
TLS_CERT_CHAIN_FAILURE,
TLS_PEER_CERTIFICATE,
TLS_ALERT
};
/*
* Note: These are used as identifier with external programs and as such, the
* values must not be changed.
*/
enum tls_fail_reason {
TLS_FAIL_UNSPECIFIED = 0,
TLS_FAIL_UNTRUSTED = 1,
TLS_FAIL_REVOKED = 2,
TLS_FAIL_NOT_YET_VALID = 3,
TLS_FAIL_EXPIRED = 4,
TLS_FAIL_SUBJECT_MISMATCH = 5,
TLS_FAIL_ALTSUBJECT_MISMATCH = 6,
TLS_FAIL_BAD_CERTIFICATE = 7,
TLS_FAIL_SERVER_CHAIN_PROBE = 8,
TLS_FAIL_DOMAIN_SUFFIX_MISMATCH = 9,
TLS_FAIL_DOMAIN_MISMATCH = 10,
TLS_FAIL_INSUFFICIENT_KEY_LEN = 11,
TLS_FAIL_DN_MISMATCH = 12,
};
#define TLS_MAX_ALT_SUBJECT 10
struct tls_cert_data {
int depth;
const char *subject;
const struct wpabuf *cert;
const u8 *hash;
size_t hash_len;
const char *altsubject[TLS_MAX_ALT_SUBJECT];
int num_altsubject;
const char *serial_num;
int tod;
};
union tls_event_data {
struct {
int depth;
const char *subject;
enum tls_fail_reason reason;
const char *reason_txt;
const struct wpabuf *cert;
} cert_fail;
struct tls_cert_data peer_cert;
struct {
int is_local;
const char *type;
const char *description;
} alert;
};
struct tls_config {
const char *opensc_engine_path;
const char *pkcs11_engine_path;
const char *pkcs11_module_path;
int fips_mode;
int cert_in_cb;
const char *openssl_ciphers;
unsigned int tls_session_lifetime;
unsigned int crl_reload_interval;
unsigned int tls_flags;
void (*event_cb)(void *ctx, enum tls_event ev,
union tls_event_data *data);
void *cb_ctx;
};
#define TLS_CONN_ALLOW_SIGN_RSA_MD5 BIT(0)
#define TLS_CONN_DISABLE_TIME_CHECKS BIT(1)
#define TLS_CONN_DISABLE_SESSION_TICKET BIT(2)
#define TLS_CONN_REQUEST_OCSP BIT(3)
#define TLS_CONN_REQUIRE_OCSP BIT(4)
#define TLS_CONN_DISABLE_TLSv1_1 BIT(5)
#define TLS_CONN_DISABLE_TLSv1_2 BIT(6)
#define TLS_CONN_EAP_FAST BIT(7)
#define TLS_CONN_DISABLE_TLSv1_0 BIT(8)
#define TLS_CONN_EXT_CERT_CHECK BIT(9)
#define TLS_CONN_REQUIRE_OCSP_ALL BIT(10)
#define TLS_CONN_SUITEB BIT(11)
#define TLS_CONN_SUITEB_NO_ECDH BIT(12)
#define TLS_CONN_DISABLE_TLSv1_3 BIT(13)
#define TLS_CONN_ENABLE_TLSv1_0 BIT(14)
#define TLS_CONN_ENABLE_TLSv1_1 BIT(15)
#define TLS_CONN_ENABLE_TLSv1_2 BIT(16)
#define TLS_CONN_TEAP_ANON_DH BIT(17)
/**
* struct tls_connection_params - Parameters for TLS connection
* @ca_cert: File or reference name for CA X.509 certificate in PEM or DER
* format
* @ca_cert_blob: ca_cert as inlined data or %NULL if not used
* @ca_cert_blob_len: ca_cert_blob length
* @ca_path: Path to CA certificates (OpenSSL specific)
* @subject_match: String to match in the subject of the peer certificate or
* %NULL to allow all subjects
* @altsubject_match: String to match in the alternative subject of the peer
* certificate or %NULL to allow all alternative subjects
* @suffix_match: Semicolon deliminated string of values to suffix match against
* the dNSName or CN of the peer certificate or %NULL to allow all domain names.
* This may allow subdomains and wildcard certificates. Each domain name label
* must have a full case-insensitive match.
* @domain_match: String to match in the dNSName or CN of the peer
* certificate or %NULL to allow all domain names. This requires a full,
* case-insensitive match.
*
* More than one match string can be provided by using semicolons to
* separate the strings (e.g., example.org;example.com). When multiple
* strings are specified, a match with any one of the values is
* considered a sufficient match for the certificate, i.e., the
* conditions are ORed together.
* @client_cert: File or reference name for client X.509 certificate in PEM or
* DER format
* @client_cert_blob: client_cert as inlined data or %NULL if not used
* @client_cert_blob_len: client_cert_blob length
* @private_key: File or reference name for client private key in PEM or DER
* format (traditional format (RSA PRIVATE KEY) or PKCS#8 (PRIVATE KEY)
* @private_key_blob: private_key as inlined data or %NULL if not used
* @private_key_blob_len: private_key_blob length
* @private_key_passwd: Passphrase for decrypted private key, %NULL if no
* passphrase is used.
* @dh_file: File name for DH/DSA data in PEM format, or %NULL if not used
* @dh_blob: dh_file as inlined data or %NULL if not used
* @dh_blob_len: dh_blob length
* @engine: 1 = use engine (e.g., a smartcard) for private key operations
* (this is OpenSSL specific for now)
* @engine_id: engine id string (this is OpenSSL specific for now)
* @ppin: pointer to the pin variable in the configuration
* (this is OpenSSL specific for now)
* @key_id: the private key's id when using engine (this is OpenSSL
* specific for now)
* @cert_id: the certificate's id when using engine
* @ca_cert_id: the CA certificate's id when using engine
* @openssl_ciphers: OpenSSL cipher configuration
* @openssl_ecdh_curves: OpenSSL ECDH curve configuration. %NULL for auto if
* supported, empty string to disable, or a colon-separated curve list.
* @flags: Parameter options (TLS_CONN_*)
* @ocsp_stapling_response: DER encoded file with cached OCSP stapling response
* or %NULL if OCSP is not enabled
* @ocsp_stapling_response_multi: DER encoded file with cached OCSP stapling
* response list (OCSPResponseList for ocsp_multi in RFC 6961) or %NULL if
* ocsp_multi is not enabled
* @check_cert_subject: Client certificate subject name matching string
*
* TLS connection parameters to be configured with tls_connection_set_params()
* and tls_global_set_params().
*
* Certificates and private key can be configured either as a reference name
* (file path or reference to certificate store) or by providing the same data
* as a pointer to the data in memory. Only one option will be used for each
* field.
*/
struct tls_connection_params {
const char *ca_cert;
const u8 *ca_cert_blob;
size_t ca_cert_blob_len;
const char *ca_path;
const char *subject_match;
const char *altsubject_match;
const char *suffix_match;
const char *domain_match;
const char *client_cert;
const char *client_cert2;
const u8 *client_cert_blob;
size_t client_cert_blob_len;
const char *private_key;
const char *private_key2;
const u8 *private_key_blob;
size_t private_key_blob_len;
const char *private_key_passwd;
const char *private_key_passwd2;
const char *dh_file;
const u8 *dh_blob;
size_t dh_blob_len;
/* OpenSSL specific variables */
int engine;
const char *engine_id;
const char *pin;
const char *key_id;
const char *cert_id;
const char *ca_cert_id;
const char *openssl_ciphers;
const char *openssl_ecdh_curves;
unsigned int flags;
const char *ocsp_stapling_response;
const char *ocsp_stapling_response_multi;
const char *check_cert_subject;
};
/**
* tls_init - Initialize TLS library
* @conf: Configuration data for TLS library
* Returns: Context data to be used as tls_ctx in calls to other functions,
* or %NULL on failure.
*
* Called once during program startup and once for each RSN pre-authentication
* session. In other words, there can be two concurrent TLS contexts. If global
* library initialization is needed (i.e., one that is shared between both
* authentication types), the TLS library wrapper should maintain a reference
* counter and do global initialization only when moving from 0 to 1 reference.
*/
void * tls_init(const struct tls_config *conf);
/**
* tls_deinit - Deinitialize TLS library
* @tls_ctx: TLS context data from tls_init()
*
* Called once during program shutdown and once for each RSN pre-authentication
* session. If global library deinitialization is needed (i.e., one that is
* shared between both authentication types), the TLS library wrapper should
* maintain a reference counter and do global deinitialization only when moving
* from 1 to 0 references.
*/
void tls_deinit(void *tls_ctx);
/**
* tls_get_errors - Process pending errors
* @tls_ctx: TLS context data from tls_init()
* Returns: Number of found error, 0 if no errors detected.
*
* Process all pending TLS errors.
*/
int tls_get_errors(void *tls_ctx);
/**
* tls_connection_init - Initialize a new TLS connection
* @tls_ctx: TLS context data from tls_init()
* Returns: Connection context data, conn for other function calls
*/
struct tls_connection * tls_connection_init(void *tls_ctx);
/**
* tls_connection_deinit - Free TLS connection data
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
*
* Release all resources allocated for TLS connection.
*/
void tls_connection_deinit(void *tls_ctx, struct tls_connection *conn);
/**
* tls_connection_established - Has the TLS connection been completed?
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: 1 if TLS connection has been completed, 0 if not.
*/
int tls_connection_established(void *tls_ctx, struct tls_connection *conn);
/**
* tls_connection_peer_serial_num - Fetch peer certificate serial number
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: Allocated string buffer containing the peer certificate serial
* number or %NULL on error.
*
* The caller is responsible for freeing the returned buffer with os_free().
*/
char * tls_connection_peer_serial_num(void *tls_ctx,
struct tls_connection *conn);
/**
* tls_connection_shutdown - Shutdown TLS connection
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: 0 on success, -1 on failure
*
* Shutdown current TLS connection without releasing all resources. New
* connection can be started by using the same conn without having to call
* tls_connection_init() or setting certificates etc. again. The new
* connection should try to use session resumption.
*/
int tls_connection_shutdown(void *tls_ctx, struct tls_connection *conn);
enum {
TLS_SET_PARAMS_ENGINE_PRV_BAD_PIN = -4,
TLS_SET_PARAMS_ENGINE_PRV_VERIFY_FAILED = -3,
TLS_SET_PARAMS_ENGINE_PRV_INIT_FAILED = -2
};
/**
* tls_connection_set_params - Set TLS connection parameters
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @params: Connection parameters
* Returns: 0 on success, -1 on failure,
* TLS_SET_PARAMS_ENGINE_PRV_INIT_FAILED (-2) on error causing PKCS#11 engine
* failure, or
* TLS_SET_PARAMS_ENGINE_PRV_VERIFY_FAILED (-3) on failure to verify the
* PKCS#11 engine private key, or
* TLS_SET_PARAMS_ENGINE_PRV_BAD_PIN (-4) on PIN error causing PKCS#11 engine
* failure.
*/
int __must_check
tls_connection_set_params(void *tls_ctx, struct tls_connection *conn,
const struct tls_connection_params *params);
/**
* tls_global_set_params - Set TLS parameters for all TLS connection
* @tls_ctx: TLS context data from tls_init()
* @params: Global TLS parameters
* Returns: 0 on success, -1 on failure,
* TLS_SET_PARAMS_ENGINE_PRV_INIT_FAILED (-2) on error causing PKCS#11 engine
* failure, or
* TLS_SET_PARAMS_ENGINE_PRV_VERIFY_FAILED (-3) on failure to verify the
* PKCS#11 engine private key, or
* TLS_SET_PARAMS_ENGINE_PRV_BAD_PIN (-4) on PIN error causing PKCS#11 engine
* failure.
*/
int __must_check tls_global_set_params(
void *tls_ctx, const struct tls_connection_params *params);
/**
* tls_global_set_verify - Set global certificate verification options
* @tls_ctx: TLS context data from tls_init()
* @check_crl: 0 = do not verify CRLs, 1 = verify CRL for the user certificate,
* 2 = verify CRL for all certificates
* @strict: 0 = allow CRL time errors, 1 = do not allow CRL time errors
* Returns: 0 on success, -1 on failure
*/
int __must_check tls_global_set_verify(void *tls_ctx, int check_crl,
int strict);
/**
* tls_connection_set_verify - Set certificate verification options
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @verify_peer: 1 = verify peer certificate
* @flags: Connection flags (TLS_CONN_*)
* @session_ctx: Session caching context or %NULL to use default
* @session_ctx_len: Length of @session_ctx in bytes.
* Returns: 0 on success, -1 on failure
*/
int __must_check tls_connection_set_verify(void *tls_ctx,
struct tls_connection *conn,
int verify_peer,
unsigned int flags,
const u8 *session_ctx,
size_t session_ctx_len);
/**
* tls_connection_get_random - Get random data from TLS connection
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @data: Structure of client/server random data (filled on success)
* Returns: 0 on success, -1 on failure
*/
int __must_check tls_connection_get_random(void *tls_ctx,
struct tls_connection *conn,
struct tls_random *data);
/**
* tls_connection_export_key - Derive keying material from a TLS connection
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @label: Label (e.g., description of the key) for PRF
* @context: Optional extra upper-layer context (max len 2^16)
* @context_len: The length of the context value
* @out: Buffer for output data from TLS-PRF
* @out_len: Length of the output buffer
* Returns: 0 on success, -1 on failure
*
* Exports keying material using the mechanism described in RFC 5705. If
* context is %NULL, context is not provided; otherwise, context is provided
* (including the case of empty context with context_len == 0).
*/
int __must_check tls_connection_export_key(void *tls_ctx,
struct tls_connection *conn,
const char *label,
const u8 *context,
size_t context_len,
u8 *out, size_t out_len);
/**
* tls_connection_get_eap_fast_key - Derive key material for EAP-FAST
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @out: Buffer for output data from TLS-PRF
* @out_len: Length of the output buffer
* Returns: 0 on success, -1 on failure
*
* Exports key material after the normal TLS key block for use with
* EAP-FAST. Most callers will want tls_connection_export_key(), but EAP-FAST
* uses a different legacy mechanism.
*/
int __must_check tls_connection_get_eap_fast_key(void *tls_ctx,
struct tls_connection *conn,
u8 *out, size_t out_len);
/**
* tls_connection_handshake - Process TLS handshake (client side)
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @in_data: Input data from TLS server
* @appl_data: Pointer to application data pointer, or %NULL if dropped
* Returns: Output data, %NULL on failure
*
* The caller is responsible for freeing the returned output data. If the final
* handshake message includes application data, this is decrypted and
* appl_data (if not %NULL) is set to point this data. The caller is
* responsible for freeing appl_data.
*
* This function is used during TLS handshake. The first call is done with
* in_data == %NULL and the library is expected to return ClientHello packet.
* This packet is then send to the server and a response from server is given
* to TLS library by calling this function again with in_data pointing to the
* TLS message from the server.
*
* If the TLS handshake fails, this function may return %NULL. However, if the
* TLS library has a TLS alert to send out, that should be returned as the
* output data. In this case, tls_connection_get_failed() must return failure
* (> 0).
*
* tls_connection_established() should return 1 once the TLS handshake has been
* completed successfully.
*/
struct wpabuf * tls_connection_handshake(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data,
struct wpabuf **appl_data);
struct wpabuf * tls_connection_handshake2(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data,
struct wpabuf **appl_data,
int *more_data_needed);
/**
* tls_connection_server_handshake - Process TLS handshake (server side)
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @in_data: Input data from TLS peer
* @appl_data: Pointer to application data pointer, or %NULL if dropped
* Returns: Output data, %NULL on failure
*
* The caller is responsible for freeing the returned output data.
*/
struct wpabuf * tls_connection_server_handshake(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data,
struct wpabuf **appl_data);
/**
* tls_connection_encrypt - Encrypt data into TLS tunnel
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @in_data: Plaintext data to be encrypted
* Returns: Encrypted TLS data or %NULL on failure
*
* This function is used after TLS handshake has been completed successfully to
* send data in the encrypted tunnel. The caller is responsible for freeing the
* returned output data.
*/
struct wpabuf * tls_connection_encrypt(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data);
/**
* tls_connection_decrypt - Decrypt data from TLS tunnel
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @in_data: Encrypted TLS data
* Returns: Decrypted TLS data or %NULL on failure
*
* This function is used after TLS handshake has been completed successfully to
* receive data from the encrypted tunnel. The caller is responsible for
* freeing the returned output data.
*/
struct wpabuf * tls_connection_decrypt(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data);
struct wpabuf * tls_connection_decrypt2(void *tls_ctx,
struct tls_connection *conn,
const struct wpabuf *in_data,
int *more_data_needed);
/**
* tls_connection_resumed - Was session resumption used
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: 1 if current session used session resumption, 0 if not
*/
int tls_connection_resumed(void *tls_ctx, struct tls_connection *conn);
enum {
TLS_CIPHER_NONE,
TLS_CIPHER_RC4_SHA /* 0x0005 */,
TLS_CIPHER_AES128_SHA /* 0x002f */,
TLS_CIPHER_RSA_DHE_AES128_SHA /* 0x0031 */,
TLS_CIPHER_ANON_DH_AES128_SHA /* 0x0034 */,
TLS_CIPHER_RSA_DHE_AES256_SHA /* 0x0039 */,
TLS_CIPHER_AES256_SHA /* 0x0035 */,
};
/**
* tls_connection_set_cipher_list - Configure acceptable cipher suites
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @ciphers: Zero (TLS_CIPHER_NONE) terminated list of allowed ciphers
* (TLS_CIPHER_*).
* Returns: 0 on success, -1 on failure
*/
int __must_check tls_connection_set_cipher_list(void *tls_ctx,
struct tls_connection *conn,
u8 *ciphers);
/**
* tls_get_version - Get the current TLS version number
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @buf: Buffer for returning the TLS version number
* @buflen: buf size
* Returns: 0 on success, -1 on failure
*
* Get the currently used TLS version number.
*/
int __must_check tls_get_version(void *tls_ctx, struct tls_connection *conn,
char *buf, size_t buflen);
/**
* tls_get_cipher - Get current cipher name
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @buf: Buffer for the cipher name
* @buflen: buf size
* Returns: 0 on success, -1 on failure
*
* Get the name of the currently used cipher.
*/
int __must_check tls_get_cipher(void *tls_ctx, struct tls_connection *conn,
char *buf, size_t buflen);
/**
* tls_connection_enable_workaround - Enable TLS workaround options
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: 0 on success, -1 on failure
*
* This function is used to enable connection-specific workaround options for
* buffer SSL/TLS implementations.
*/
int __must_check tls_connection_enable_workaround(void *tls_ctx,
struct tls_connection *conn);
/**
* tls_connection_client_hello_ext - Set TLS extension for ClientHello
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* @ext_type: Extension type
* @data: Extension payload (%NULL to remove extension)
* @data_len: Extension payload length
* Returns: 0 on success, -1 on failure
*/
int __must_check tls_connection_client_hello_ext(void *tls_ctx,
struct tls_connection *conn,
int ext_type, const u8 *data,
size_t data_len);
/**
* tls_connection_get_failed - Get connection failure status
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
*
* Returns >0 if connection has failed, 0 if not.
*/
int tls_connection_get_failed(void *tls_ctx, struct tls_connection *conn);
/**
* tls_connection_get_read_alerts - Get connection read alert status
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: Number of times a fatal read (remote end reported error) has
* happened during this connection.
*/
int tls_connection_get_read_alerts(void *tls_ctx, struct tls_connection *conn);
/**
* tls_connection_get_write_alerts - Get connection write alert status
* @tls_ctx: TLS context data from tls_init()
* @conn: Connection context data from tls_connection_init()
* Returns: Number of times a fatal write (locally detected error) has happened
* during this connection.
*/
int tls_connection_get_write_alerts(void *tls_ctx,
struct tls_connection *conn);
typedef int (*tls_session_ticket_cb)
(void *ctx, const u8 *ticket, size_t len, const u8 *client_random,
const u8 *server_random, u8 *master_secret);
int __must_check tls_connection_set_session_ticket_cb(
void *tls_ctx, struct tls_connection *conn,
tls_session_ticket_cb cb, void *ctx);
void tls_connection_set_log_cb(struct tls_connection *conn,
void (*log_cb)(void *ctx, const char *msg),
void *ctx);
#define TLS_BREAK_VERIFY_DATA BIT(0)
#define TLS_BREAK_SRV_KEY_X_HASH BIT(1)
#define TLS_BREAK_SRV_KEY_X_SIGNATURE BIT(2)
#define TLS_DHE_PRIME_511B BIT(3)
#define TLS_DHE_PRIME_767B BIT(4)
#define TLS_DHE_PRIME_15 BIT(5)
#define TLS_DHE_PRIME_58B BIT(6)
#define TLS_DHE_NON_PRIME BIT(7)
void tls_connection_set_test_flags(struct tls_connection *conn, u32 flags);
int tls_get_library_version(char *buf, size_t buf_len);
void tls_connection_set_success_data(struct tls_connection *conn,
struct wpabuf *data);
void tls_connection_set_success_data_resumed(struct tls_connection *conn);
const struct wpabuf *
tls_connection_get_success_data(struct tls_connection *conn);
void tls_connection_remove_session(struct tls_connection *conn);
/**
* tls_get_tls_unique - Fetch "tls-unique" for channel binding
* @conn: Connection context data from tls_connection_init()
* @buf: Buffer for returning the value
* @max_len: Maximum length of the buffer in bytes
* Returns: Number of bytes written to buf or -1 on error
*
* This function can be used to fetch "tls-unique" (RFC 5929, Section 3) which
* is the first TLS Finished message sent in the most recent TLS handshake of
* the TLS connection.
*/
int tls_get_tls_unique(struct tls_connection *conn, u8 *buf, size_t max_len);
/**
* tls_connection_get_cipher_suite - Get current TLS cipher suite
* @conn: Connection context data from tls_connection_init()
* Returns: TLS cipher suite of the current connection or 0 on error
*/
u16 tls_connection_get_cipher_suite(struct tls_connection *conn);
#endif /* TLS_H */