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The prototypes for the following functions lie in ‘gnutls/gnutls.h’.
session: is a gnutls_session_t structure.
This function will return the last alert number received. This
function should be called when GNUTLS_E_WARNING_ALERT_RECEIVED or
GNUTLS_E_FATAL_ALERT_RECEIVED errors are returned by a gnutls
function. The peer may send alerts if he encounters an error.
If no alert has been received the returned value is undefined.
Returns: the last alert received, a
gnutls_alert_description_t value.
alert: is an alert number.
This function will return a string that describes the given alert
number, or NULL . See gnutls_alert_get() .
Returns: string corresponding to gnutls_alert_description_t value.
alert: is an alert number.
This function will return a string of the name of the alert.
Returns: string corresponding to gnutls_alert_description_t value.
Since: 3.0
session: is a gnutls_session_t structure.
level: is the level of the alert
desc: is the alert description
This function will send an alert to the peer in order to inform him of something important (eg. his Certificate could not be verified). If the alert level is Fatal then the peer is expected to close the connection, otherwise he may ignore the alert and continue.
The error code of the underlying record send function will be
returned, so you may also receive GNUTLS_E_INTERRUPTED or
GNUTLS_E_AGAIN as well.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
err: is an integer
Sends an alert to the peer depending on the error code returned by
a gnutls function. This function will call gnutls_error_to_alert()
to determine the appropriate alert to send.
This function may also return GNUTLS_E_AGAIN , or
GNUTLS_E_INTERRUPTED .
If the return value is GNUTLS_E_INVALID_REQUEST , then no alert has
been sent to the peer.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
sc: is a pointer to a gnutls_anon_client_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
sc: is a pointer to a gnutls_anon_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
sc: is a gnutls_anon_client_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
sc: is a gnutls_anon_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
res: is a gnutls_anon_server_credentials_t structure
func: is the function to be called
This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for anonymous authentication.
The callback should return GNUTLS_E_SUCCESS (0) on success.
res: is a gnutls_anon_server_credentials_t structure
dh_params: is a structure that holds Diffie-Hellman parameters.
This function will set the Diffie-Hellman parameters for an anonymous server to use. These parameters will be used in Anonymous Diffie-Hellman cipher suites.
res: is a gnutls_certificate_credentials_t structure
func: is the function to be called
This function will set a callback in order for the server to get
the Diffie-Hellman parameters for anonymous authentication. The
callback should return GNUTLS_E_SUCCESS (0) on success.
session: is a gnutls_session_t structure.
Returns the type of credentials that were used for client authentication. The returned information is to be used to distinguish the function used to access authentication data.
Returns: The type of credentials for the client authentication
schema, a gnutls_credentials_type_t type.
session: is a gnutls_session_t structure.
Returns type of credentials for the current authentication schema. The returned information is to be used to distinguish the function used to access authentication data.
Eg. for CERTIFICATE ciphersuites (key exchange algorithms:
GNUTLS_KX_RSA , GNUTLS_KX_DHE_RSA ), the same function are to be
used to access the authentication data.
Returns: The type of credentials for the current authentication
schema, a gnutls_credentials_type_t type.
session: is a gnutls_session_t structure.
Returns the type of credentials that were used for server authentication. The returned information is to be used to distinguish the function used to access authentication data.
Returns: The type of credentials for the server authentication
schema, a gnutls_credentials_type_t type.
session: is a gnutls_session_t structure.
how: is an integer
Terminates the current TLS/SSL connection. The connection should
have been initiated using gnutls_handshake() . how should be one
of GNUTLS_SHUT_RDWR , GNUTLS_SHUT_WR .
In case of GNUTLS_SHUT_RDWR the TLS session gets
terminated and further receives and sends will be disallowed. If
the return value is zero you may continue using the underlying
transport layer. GNUTLS_SHUT_RDWR sends an alert containing a close
request and waits for the peer to reply with the same message.
In case of GNUTLS_SHUT_WR the TLS session gets terminated
and further sends will be disallowed. In order to reuse the
connection you should wait for an EOF from the peer.
GNUTLS_SHUT_WR sends an alert containing a close request.
Note that not all implementations will properly terminate a TLS connection. Some of them, usually for performance reasons, will terminate only the underlying transport layer, and thus not distinguishing between a malicious party prematurely terminating the connection and normal termination.
This function may also return GNUTLS_E_AGAIN or
GNUTLS_E_INTERRUPTED ; cf. gnutls_record_get_direction() .
Returns: GNUTLS_E_SUCCESS on success, or an error code, see
function documentation for entire semantics.
session: is a gnutls session
This function will return the peer’s certificate activation time. This is the creation time for openpgp keys.
Returns: (time_t)-1 on error.
Deprecated: gnutls_certificate_verify_peers2() now verifies activation times.
res: is a pointer to a gnutls_certificate_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
session: is a gnutls session
Get whether client certificate is requested or not.
Returns: 0 if the peer (server) did not request client authentication or 1 otherwise, or a negative error code in case of error.
session: is a gnutls session
This function will return the peer’s certificate expiration time.
Returns: (time_t)-1 on error.
Deprecated: gnutls_certificate_verify_peers2() now verifies expiration times.
sc: is a gnutls_certificate_credentials_t structure.
This function will delete all the CA name in the given credentials. Clients may call this to save some memory since in client side the CA names are not used. Servers might want to use this function if a large list of trusted CAs is present and sending the names of it would just consume bandwidth without providing information to client.
CA names are used by servers to advertise the CAs they support to clients.
sc: is a gnutls_certificate_credentials_t structure.
This function will delete all the CAs associated with the given
credentials. Servers that do not use
gnutls_certificate_verify_peers2() may call this to save some
memory.
sc: is a gnutls_certificate_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
This function does not free any temporary parameters associated with this structure (ie RSA and DH parameters are not freed by this function).
sc: is a gnutls_certificate_credentials_t structure.
This function will delete all the CRLs associated with the given credentials.
sc: is a gnutls_certificate_credentials_t structure.
This function will delete all the keys and the certificates associated with the given credentials. This function must not be called when a TLS negotiation that uses the credentials is in progress.
sc: is a gnutls_certificate_credentials_t structure.
cert: is the certificate to find issuer for
issuer: Will hold the issuer if any. Should be treated as constant.
flags: Use zero.
This function will return the issuer of a given certificate.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a
negative error value.
Since: 3.0
session: is a gnutls session
Gets the certificate as sent to the peer in the last handshake. The certificate is in raw (DER) format. No certificate list is being returned. Only the first certificate.
Returns: a pointer to a gnutls_datum_t containing our
certificates, or NULL in case of an error or if no certificate
was used.
session: is a gnutls session
list_size: is the length of the certificate list
Get the peer’s raw certificate (chain) as sent by the peer. These certificates are in raw format (DER encoded for X.509). In case of a X.509 then a certificate list may be present. The first certificate in the list is the peer’s certificate, following the issuer’s certificate, then the issuer’s issuer etc.
In case of OpenPGP keys a single key will be returned in raw format.
Returns: a pointer to a gnutls_datum_t containing our
certificates, or NULL in case of an error or if no certificate
was used.
session: is a pointer to a gnutls_session_t structure.
status: is 0 or 1
If status is non zero, this function will order gnutls not to send the rdnSequence in the certificate request message. That is the server will not advertise its trusted CAs to the peer. If status is zero then the default behaviour will take effect, which is to advertise the server’s trusted CAs.
This function has no effect in clients, and in authentication methods other than certificate with X.509 certificates.
session: is a gnutls_session_t structure.
req: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE
This function specifies if we (in case of a server) are going to
send a certificate request message to the client. If req is
GNUTLS_CERT_REQUIRE then the server will return an error if the
peer does not provide a certificate. If you do not call this
function then the client will not be asked to send a certificate.
res: is a gnutls_certificate_credentials_t structure
dh_params: is a structure that holds Diffie-Hellman parameters.
This function will set the Diffie-Hellman parameters for a certificate server to use. These parameters will be used in Ephemeral Diffie-Hellman cipher suites. Note that only a pointer to the parameters are stored in the certificate handle, so if you deallocate the parameters before the certificate is deallocated, you must change the parameters stored in the certificate first.
res: is a gnutls_certificate_credentials_t structure
func: is the function to be called
This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for certificate
authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.
cred: is a gnutls_certificate_credentials_t structure.
func: is the callback function
This function sets a callback to be called in order to retrieve the
certificate to be used in the handshake. You are advised
to use gnutls_certificate_set_retrieve_function2() because it
is much more efficient in the processing it requires from gnutls.
The callback’s function prototype is: int (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int nreqs, const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length, gnutls_retr2_st* st);
req_ca_cert is only used in X.509 certificates.
Contains a list with the CA names that the server considers trusted.
Normally we should send a certificate that is signed
by one of these CAs. These names are DER encoded. To get a more
meaningful value use the function gnutls_x509_rdn_get() .
pk_algos contains a list with server’s acceptable signature algorithms.
The certificate returned should support the server’s given algorithms.
st should contain the certificates and private keys.
If the callback function is provided then gnutls will call it, in the handshake, after the certificate request message has been received.
In server side pk_algos and req_ca_dn are NULL.
The callback function should set the certificate list to be sent, and return 0 on success. If no certificate was selected then the number of certificates should be set to zero. The value (-1) indicates error and the handshake will be terminated.
Since: 3.0
res: is a gnutls_certificate_credentials_t structure
flags: are the flags
This function will set the flags to be used at verification of the
certificates. Flags must be OR of the
gnutls_certificate_verify_flags enumerations.
cred: is a gnutls_certificate_credentials_t structure.
func: is the callback function
This function sets a callback to be called when peer’s certificate has been received in order to verify it on receipt rather than doing after the handshake is completed.
The callback’s function prototype is: int (*callback)(gnutls_session_t);
If the callback function is provided then gnutls will call it, in the
handshake, just after the certificate message has been received.
To verify or obtain the certificate the gnutls_certificate_verify_peers2() ,
gnutls_certificate_type_get() , gnutls_certificate_get_peers() functions
can be used.
The callback function should return 0 for the handshake to continue or non-zero to terminate.
Since: 2.10.0
res: is a gnutls_certificate_credentials structure
max_bits: is the number of bits of an acceptable certificate (default 8200)
max_depth: is maximum depth of the verification of a certificate chain (default 5)
This function will set some upper limits for the default
verification function, gnutls_certificate_verify_peers2() , to avoid
denial of service attacks. You can set them to zero to disable
limits.
res: is a gnutls_certificate_credentials_t structure.
crl_list: is a list of trusted CRLs. They should have been verified before.
crl_list_size: holds the size of the crl_list
This function adds the trusted CRLs in order to verify client or
server certificates. In case of a client this is not required to
be called if the certificates are not verified using
gnutls_certificate_verify_peers2() . This function may be called
multiple times.
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
Since: 2.4.0
res: is a gnutls_certificate_credentials_t structure.
crlfile: is a file containing the list of verified CRLs (DER or PEM list)
type: is PEM or DER
This function adds the trusted CRLs in order to verify client or server
certificates. In case of a client this is not required
to be called if the certificates are not verified using
gnutls_certificate_verify_peers2() .
This function may be called multiple times.
Returns: number of CRLs processed or a negative error code on error.
res: is a gnutls_certificate_credentials_t structure.
CRL: is a list of trusted CRLs. They should have been verified before.
type: is DER or PEM
This function adds the trusted CRLs in order to verify client or
server certificates. In case of a client this is not required to
be called if the certificates are not verified using
gnutls_certificate_verify_peers2() . This function may be called
multiple times.
Returns: number of CRLs processed, or a negative error code on error.
res: is a gnutls_certificate_credentials_t structure.
cert_list: contains a certificate list (path) for the specified private key
cert_list_size: holds the size of the certificate list
key: is a gnutls_x509_privkey_t key
This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t structure. This function may be
called more than once, in case multiple keys/certificates exist for
the server. For clients that wants to send more than its own end
entity certificate (e.g., also an intermediate CA cert) then put
the certificate chain in cert_list .
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
Since: 2.4.0
res: is a gnutls_certificate_credentials_t structure.
certfile: is a file that containing the certificate list (path) for the specified private key, in PKCS7 format, or a list of certificates
keyfile: is a file that contains the private key
type: is PEM or DER
This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t structure. This function may be
called more than once, in case multiple keys/certificates exist for
the server. For clients that need to send more than its own end
entity certificate, e.g., also an intermediate CA cert, then the
certfile must contain the ordered certificate chain.
This function can also accept PKCS 11 URLs at keyfile and certfile . In that case it
will import the private key and certificate indicated by the URLs.
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
res: is a gnutls_certificate_credentials_t structure.
cert: contains a certificate list (path) for the specified private key
key: is the private key, or NULL
type: is PEM or DER
This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once, in case multiple keys/certificates exist for the server.
Note that the keyUsage (2.5.29.15) PKIX extension in X.509 certificates is supported. This means that certificates intended for signing cannot be used for ciphersuites that require encryption.
If the certificate and the private key are given in PEM encoding then the strings that hold their values must be null terminated.
The key may be NULL if you are using a sign callback, see
gnutls_sign_callback_set() .
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
res: is a gnutls_certificate_credentials_t structure.
pkcs12file: filename of file containing PKCS12 blob.
type: is PEM or DER of the pkcs12file .
password: optional password used to decrypt PKCS12 file, bags and keys.
This function sets a certificate/private key pair and/or a CRL in the gnutls_certificate_credentials_t structure. This function may be called more than once (in case multiple keys/certificates exist for the server).
PKCS12 files with a MAC, encrypted bags and PKCS 8
private keys are supported. However,
only password based security, and the same password for all
operations, are supported.
PKCS12 file may contain many keys and/or certificates, and there
is no way to identify which key/certificate pair you want. You
should make sure the PKCS12 file only contain one key/certificate
pair and/or one CRL.
It is believed that the limitations of this function is acceptable for most usage, and that any more flexibility would introduce complexity that would make it harder to use this functionality at all.
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
res: is a gnutls_certificate_credentials_t structure.
p12blob: the PKCS12 blob.
type: is PEM or DER of the pkcs12file .
password: optional password used to decrypt PKCS12 file, bags and keys.
This function sets a certificate/private key pair and/or a CRL in the gnutls_certificate_credentials_t structure. This function may be called more than once (in case multiple keys/certificates exist for the server).
MAC: ed PKCS12 files are supported. Encrypted PKCS12 bags are
supported. Encrypted PKCS8 private keys are supported. However,
only password based security, and the same password for all
operations, are supported.
PKCS12 file may contain many keys and/or certificates, and there
is no way to identify which key/certificate pair you want. You
should make sure the PKCS12 file only contain one key/certificate
pair and/or one CRL.
It is believed that the limitations of this function is acceptable for most usage, and that any more flexibility would introduce complexity that would make it harder to use this functionality at all.
Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.
Since: 2.8.0
res: is a gnutls_certificate_credentials_t structure.
ca_list: is a list of trusted CAs
ca_list_size: holds the size of the CA list
This function adds the trusted CAs in order to verify client
or server certificates. In case of a client this is not required
to be called if the certificates are not verified using
gnutls_certificate_verify_peers2() .
This function may be called multiple times.
In case of a server the CAs set here will be sent to the client if
a certificate request is sent. This can be disabled using
gnutls_certificate_send_x509_rdn_sequence() .
Returns: the number of certificates processed or a negative error code on error.
Since: 2.4.0
cred: is a gnutls_certificate_credentials_t structure.
cafile: is a file containing the list of trusted CAs (DER or PEM list)
type: is PEM or DER
This function adds the trusted CAs in order to verify client or
server certificates. In case of a client this is not required to
be called if the certificates are not verified using
gnutls_certificate_verify_peers2() . This function may be called
multiple times.
In case of a server the names of the CAs set here will be sent to
the client if a certificate request is sent. This can be disabled
using gnutls_certificate_send_x509_rdn_sequence() .
This function can also accept PKCS 11 URLs. In that case it
will import all certificates that are marked as trusted.
Returns: number of certificates processed, or a negative error code on error.
res: is a gnutls_certificate_credentials_t structure.
ca: is a list of trusted CAs or a DER certificate
type: is DER or PEM
This function adds the trusted CAs in order to verify client or
server certificates. In case of a client this is not required to be
called if the certificates are not verified using
gnutls_certificate_verify_peers2() . This function may be called
multiple times.
In case of a server the CAs set here will be sent to the client if
a certificate request is sent. This can be disabled using
gnutls_certificate_send_x509_rdn_sequence() .
Returns: the number of certificates processed or a negative error code on error.
session: is a gnutls_session_t structure.
The certificate type is by default X.509, unless it is negotiated as a TLS extension.
Returns: the currently used gnutls_certificate_type_t certificate
type.
name: is a certificate type name
The names are compared in a case insensitive way.
Returns: a gnutls_certificate_type_t for the specified in a
string certificate type, or GNUTLS_CRT_UNKNOWN on error.
type: is a certificate type
Convert a gnutls_certificate_type_t type to a string.
Returns: a string that contains the name of the specified
certificate type, or NULL in case of unknown types.
Get a list of certificate types. Note that to be able to use
OpenPGP certificates, you must link to libgnutls-extra and call
gnutls_global_init_extra() .
Returns: a (0)-terminated list of gnutls_certificate_type_t
integers indicating the available certificate types.
session: is a gnutls session
status: is the output of the verification
This function will try to verify the peer’s certificate and return
its status (trusted, invalid etc.). The value of status should
be one or more of the gnutls_certificate_status_t enumerated
elements bitwise or’d. To avoid denial of service attacks some
default upper limits regarding the certificate key size and chain
size are set. To override them use
gnutls_certificate_set_verify_limits() .
Note that you must also check the peer’s name in order to check if the verified certificate belongs to the actual peer.
This function uses gnutls_x509_crt_list_verify() with the CAs in
the credentials as trusted CAs.
Returns: a negative error code on error and GNUTLS_E_SUCCESS (0) on success.
req_version: version string to compare with, or NULL .
Check GnuTLS Library version.
See GNUTLS_VERSION for a suitable req_version string.
Returns: Check that the version of the library is at
minimum the one given as a string in req_version and return the
actual version string of the library; return NULL if the
condition is not met. If NULL is passed to this function no
check is done and only the version string is returned.
session: is a gnutls_session_t structure.
Get currently used cipher.
Returns: the currently used cipher, a gnutls_cipher_algorithm_t
type.
name: is a cipher algorithm name
The names are compared in a case insensitive way.
Returns: return a gnutls_cipher_algorithm_t value corresponding to
the specified cipher, or GNUTLS_CIPHER_UNKNOWN on error.
algorithm: is an encryption algorithm
Get key size for cipher.
Returns: length (in bytes) of the given cipher’s key size, or 0 if the given cipher is invalid.
algorithm: is an encryption algorithm
Convert a gnutls_cipher_algorithm_t type to a string.
Returns: a pointer to a string that contains the name of the
specified cipher, or NULL .
Get a list of supported cipher algorithms. Note that not
necessarily all ciphers are supported as TLS cipher suites. For
example, DES is not supported as a cipher suite, but is supported
for other purposes (e.g., PKCS8 or similar).
This function is not thread safe.
Returns: a (0)-terminated list of gnutls_cipher_algorithm_t
integers indicating the available ciphers.
kx_algorithm: is a Key exchange algorithm
cipher_algorithm: is a cipher algorithm
mac_algorithm: is a MAC algorithm
Note that the full cipher suite name must be prepended by TLS or SSL depending of the protocol in use.
Returns: a string that contains the name of a TLS cipher suite,
specified by the given algorithms, or NULL .
idx: index of cipher suite to get information about, starts on 0.
cs_id: output buffer with room for 2 bytes, indicating cipher suite value
kx: output variable indicating key exchange algorithm, or NULL .
cipher: output variable indicating cipher, or NULL .
mac: output variable indicating MAC algorithm, or NULL .
min_version: output variable indicating TLS protocol version, or NULL .
Get information about supported cipher suites. Use the function iteratively to get information about all supported cipher suites. Call with idx=0 to get information about first cipher suite, then idx=1 and so on until the function returns NULL.
Returns: the name of idx cipher suite, and set the information
about the cipher suite in the output variables. If idx is out of
bounds, NULL is returned.
session: is a gnutls_session_t structure.
Get currently used compression algorithm.
Returns: the currently used compression method, a
gnutls_compression_method_t value.
name: is a compression method name
The names are compared in a case insensitive way.
Returns: an id of the specified in a string compression method, or
GNUTLS_COMP_UNKNOWN on error.
algorithm: is a Compression algorithm
Convert a gnutls_compression_method_t value to a string.
Returns: a pointer to a string that contains the name of the
specified compression algorithm, or NULL .
Get a list of compression methods.
Returns: a zero-terminated list of gnutls_compression_method_t
integers indicating the available compression methods.
session: is a gnutls_session_t structure.
Clears all the credentials previously set in this session.
session: is a gnutls_session_t structure.
type: is the type of the credentials
cred: is a pointer to a structure.
Sets the needed credentials for the specified type. Eg username,
password - or public and private keys etc. The cred parameter is
a structure that depends on the specified type and on the current
session (client or server).
In order to minimize memory usage, and share credentials between
several threads gnutls keeps a pointer to cred, and not the whole
cred structure. Thus you will have to keep the structure allocated
until you call gnutls_deinit() .
For GNUTLS_CRD_ANON , cred should be
gnutls_anon_client_credentials_t in case of a client. In case of
a server it should be gnutls_anon_server_credentials_t .
For GNUTLS_CRD_SRP , cred should be gnutls_srp_client_credentials_t
in case of a client, and gnutls_srp_server_credentials_t , in case
of a server.
For GNUTLS_CRD_CERTIFICATE , cred should be
gnutls_certificate_credentials_t .
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
session: is a gnutls_session_t structure.
session_entry: is the session data (not key)
Check if database entry has expired. This function is to be used when you want to clear unnecessary sessions which occupy space in your backend.
Returns: Returns GNUTLS_E_EXPIRED , if the database entry has
expired or 0 otherwise.
session: is a gnutls_session_t structure.
Get db function pointer.
Returns: the pointer that will be sent to db store, retrieve and delete functions, as the first argument.
session: is a gnutls_session_t structure.
This function will remove the current session data from the
session database. This will prevent future handshakes reusing
these session data. This function should be called if a session
was terminated abnormally, and before gnutls_deinit() is called.
Normally gnutls_deinit() will remove abnormally terminated
sessions.
session: is a gnutls_session_t structure.
seconds: is the number of seconds.
Set the expiration time for resumed sessions. The default is 3600 (one hour) at the time of this writing.
session: is a gnutls_session_t structure.
ptr: is the pointer
Sets the pointer that will be provided to db store, retrieve and delete functions, as the first argument.
session: is a gnutls_session_t structure.
rem_func: is the function.
Sets the function that will be used to remove data from the resumed sessions database. This function must return 0 on success.
The first argument to rem_func will be null unless
gnutls_db_set_ptr() has been called.
session: is a gnutls_session_t structure.
retr_func: is the function.
Sets the function that will be used to retrieve data from the resumed sessions database. This function must return a gnutls_datum_t containing the data on success, or a gnutls_datum_t containing null and 0 on failure.
The datum’s data must be allocated using the function
gnutls_malloc() .
The first argument to retr_func will be null unless
gnutls_db_set_ptr() has been called.
session: is a gnutls_session_t structure.
store_func: is the function
Sets the function that will be used to store data in the resumed sessions database. This function must return 0 on success.
The first argument to store_func will be null unless
gnutls_db_set_ptr() has been called.
session: is a gnutls_session_t structure.
This function clears all buffers associated with the session .
This function will also remove session data from the session
database if the session was terminated abnormally.
session: is a gnutls session
raw_gen: will hold the generator.
raw_prime: will hold the prime.
This function will return the group parameters used in the last
Diffie-Hellman key exchange with the peer. These are the prime and
the generator used. This function should be used for both
anonymous and ephemeral Diffie-Hellman. The output parameters must
be freed with gnutls_free() .
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls session
Get the Diffie-Hellman public key bit size. Can be used for both anonymous and ephemeral Diffie-Hellman.
Returns: The public key bit size used in the last Diffie-Hellman key exchange with the peer, or a negative error code in case of error.
session: is a gnutls session
This function will return the bits of the prime used in the last Diffie-Hellman key exchange with the peer. Should be used for both anonymous and ephemeral Diffie-Hellman. Note that some ciphers, like RSA and DSA without DHE, do not use a Diffie-Hellman key exchange, and then this function will return 0.
Returns: The Diffie-Hellman bit strength is returned, or 0 if no Diffie-Hellman key exchange was done, or a negative error code on failure.
session: is a gnutls session
raw_key: will hold the public key.
This function will return the peer’s public key used in the last
Diffie-Hellman key exchange. This function should be used for both
anonymous and ephemeral Diffie-Hellman. The output parameters must
be freed with gnutls_free() .
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls session
This function will return the bits used in the last Diffie-Hellman key exchange with the peer. Should be used for both anonymous and ephemeral Diffie-Hellman.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
dst: Is the destination structure, which should be initialized.
src: Is the source structure
This function will copy the DH parameters structure from source to destination.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
dh_params: Is a structure that holds the prime numbers
This function will deinitialize the DH parameters structure.
params: Holds the DH parameters
format: the format of output params. One of PEM or DER.
params_data: will contain a PKCS3 DHParams structure PEM or DER encoded
params_data_size: holds the size of params_data (and will be replaced by the actual size of parameters)
This function will export the given dh parameters to a PKCS3 DHParams structure. This is the format generated by "openssl dhparam" tool. If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.
If the structure is PEM encoded, it will have a header of "BEGIN DH PARAMETERS".
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
params: Holds the DH parameters
prime: will hold the new prime
generator: will hold the new generator
bits: if non null will hold the secret key’s number of bits
This function will export the pair of prime and generator for use
in the Diffie-Hellman key exchange. The new parameters will be
allocated using gnutls_malloc() and will be stored in the
appropriate datum.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
params: Is the structure that the DH parameters will be stored
bits: is the prime’s number of bits
This function will generate a new pair of prime and generator for use in
the Diffie-Hellman key exchange. The new parameters will be allocated using
gnutls_malloc() and will be stored in the appropriate datum.
This function is normally slow.
Do not set the number of bits directly, use gnutls_sec_param_to_pk_bits() to
get bits for GNUTLS_PK_DSA .
Also note that the DH parameters are only useful to servers.
Since clients use the parameters sent by the server, it’s of
no use to call this in client side.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
params: A structure where the parameters will be copied to
pkcs3_params: should contain a PKCS3 DHParams structure PEM or DER encoded
format: the format of params. PEM or DER.
This function will extract the DHParams found in a PKCS3 formatted structure. This is the format generated by "openssl dhparam" tool.
If the structure is PEM encoded, it should have a header of "BEGIN DH PARAMETERS".
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
dh_params: Is a structure that will hold the prime numbers
prime: holds the new prime
generator: holds the new generator
This function will replace the pair of prime and generator for use in the Diffie-Hellman key exchange. The new parameters should be stored in the appropriate gnutls_datum.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
dh_params: Is a structure that will hold the prime numbers
This function will initialize the DH parameters structure.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
session: is a gnutls_session_t structure.
bits: is the number of bits
This function sets the number of bits, for use in a Diffie-Hellman key exchange. This is used both in DH ephemeral and DH anonymous cipher suites. This will set the minimum size of the prime that will be used for the handshake.
In the client side it sets the minimum accepted number of bits. If
a server sends a prime with less bits than that
GNUTLS_E_DH_PRIME_UNACCEPTABLE will be returned by the handshake.
This function has no effect in server side.
session: is a gnutls_session_t structure.
Returns the currently used elliptic curve. Only valid when using an elliptic curve ciphersuite.
Returns: the currently used curve, a gnutls_ecc_curve_t
type.
Since: 3.0
curve: is an ECC curve
Convert a gnutls_ecc_curve_t value to a string.
Returns: a string that contains the name of the specified
curve or NULL .
Since: 3.0
curve: is an ECC curve
Returns the size in bytes of the curve.
Returns: a the size or (0).
Since: 3.0
Get the list of supported elliptic curves.
This function is not thread safe.
Returns: Return a (0)-terminated list of gnutls_ecc_curve_t
integers indicating the available curves.
error: is a GnuTLS error code, a negative error code
If a GnuTLS function returns a negative error code you may feed that value to this function to see if the error condition is fatal. Note that you may also want to check the error code manually, since some non-fatal errors to the protocol (such as a warning alert or a rehandshake request) may be fatal for your program.
This function is only useful if you are dealing with errors from the record layer or the handshake layer.
Returns: 1 if the error code is fatal, for positive error values,
0 is returned. For unknown error values, -1 is returned.
err: is a negative integer
level: the alert level will be stored there
Get an alert depending on the error code returned by a gnutls
function. All alerts sent by this function should be considered
fatal. The only exception is when err is GNUTLS_E_REHANDSHAKE ,
where a warning alert should be sent to the peer indicating that no
renegotiation will be performed.
If there is no mapping to a valid alert the alert to indicate internal error is returned.
Returns: the alert code to use for a particular error code.
algo: is a digest algorithm
data: is the data
result: is the place where the result will be copied (may be null).
result_size: should hold the size of the result. The actual size of the returned result will also be copied there.
This function will calculate a fingerprint (actually a hash), of the given data. The result is not printable data. You should convert it to hex, or to something else printable.
This is the usual way to calculate a fingerprint of an X.509 DER encoded certificate. Note however that the fingerprint of an OpenPGP is not just a hash and cannot be calculated with this function.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
This function deinitializes the global data, that were initialized
using gnutls_global_init() .
Note! This function is not thread safe. See the discussion for
gnutls_global_init() for more information.
This function initializes the global data to defaults.
In order to free resources you may call gnutls_global_deinit()
when gnutls usage is no longer needed.
Note that this function will also initialize the underlying crypto backend, if it has not been initialized before.
This function increments a global counter, so that
gnutls_global_deinit() only releases resources when it has been
called as many times as gnutls_global_init() . This is useful when
GnuTLS is used by more than one library in an application. This
function can be called many times, but will only do something the
first time.
Note! This function is not thread safe. If two threads call this function simultaneously, they can cause a race between checking the global counter and incrementing it, causing both threads to execute the library initialization code. That would lead to a memory leak. To handle this, your application could invoke this function after aquiring a thread mutex. To ignore the potential memory leak is also an option.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
log_func: it is the audit log function
This is the function where you set the logging function gnutls is
going to use. This is different from gnutls_global_set_log_function()
because it will report the session of the event if any. Note that
that session might be null if there is no corresponding TLS session.
gnutls_audit_log_func is of the form,
void (*gnutls_audit_log_func)( gnutls_session_t, int level, const char*);
Since: 3.0
log_func: it’s a log function
This is the function where you set the logging function gnutls is going to use. This function only accepts a character array. Normally you may not use this function since it is only used for debugging purposes.
gnutls_log_func is of the form,
void (*gnutls_log_func)( int level, const char*);
level: it’s an integer from 0 to 9.
This is the function that allows you to set the log level. The level is an integer between 0 and 9. Higher values mean more verbosity. The default value is 0. Larger values should only be used with care, since they may reveal sensitive information.
Use a log level over 10 to enable all debugging options.
alloc_func: it’s the default memory allocation function. Like malloc() .
secure_alloc_func: This is the memory allocation function that will be used for sensitive data.
is_secure_func: a function that returns 0 if the memory given is not secure. May be NULL.
realloc_func: A realloc function
free_func: The function that frees allocated data. Must accept a NULL pointer.
This is the function where you set the memory allocation functions
gnutls is going to use. By default the libc’s allocation functions
(malloc() , free() ), are used by gnutls, to allocate both sensitive
and not sensitive data. This function is provided to set the
memory allocation functions to something other than the defaults
This function must be called before gnutls_global_init() is called.
This function is not thread safe.
init: mutex initialization function
deinit: mutex deinitialization function
lock: mutex locking function
unlock: mutex unlocking function
With this function you are allowed to override the default mutex locks used in some parts of gnutls and dependent libraries. This function should be used if you have complete control of your program and libraries. Do not call this function from a library. Instead only initialize gnutls and the default OS mutex locks will be used.
This function must be called before gnutls_global_init() .
Since: 2.12.0
time_func: it’s the system time function, a gnutls_time_func() callback.
This is the function where you can override the default system time function. The application provided function should behave the same as the standard function.
Since: 2.12.0
session: is a gnutls_session_t structure.
This function does the handshake of the TLS/SSL protocol, and initializes the TLS connection.
This function will fail if any problem is encountered, and will return a negative error code. In case of a client, if the client has asked to resume a session, but the server couldn’t, then a full handshake will be performed.
The non-fatal errors such as GNUTLS_E_AGAIN and
GNUTLS_E_INTERRUPTED interrupt the handshake procedure, which
should be resumed later. Call this function again, until it
returns 0; cf. gnutls_record_get_direction() and
gnutls_error_is_fatal() .
If this function is called by a server after a rehandshake request
then GNUTLS_E_GOT_APPLICATION_DATA or
GNUTLS_E_WARNING_ALERT_RECEIVED may be returned. Note that these
are non fatal errors, only in the specific case of a rehandshake.
Their meaning is that the client rejected the rehandshake request or
in the case of GNUTLS_E_GOT_APPLICATION_DATA it might also mean that
some data were pending.
Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.
session: is a gnutls_session_t structure.
This function is only useful to check where the last performed handshake failed. If the previous handshake succeed or was not performed at all then no meaningful value will be returned.
Check gnutls_handshake_description_t in gnutls.h for the
available handshake descriptions.
Returns: the last handshake message type received, a
gnutls_handshake_description_t .
session: is a gnutls_session_t structure.
This function is only useful to check where the last performed handshake failed. If the previous handshake succeed or was not performed at all then no meaningful value will be returned.
Check gnutls_handshake_description_t in gnutls.h for the
available handshake descriptions.
Returns: the last handshake message type sent, a
gnutls_handshake_description_t .
session: is a gnutls_session_t structure.
max: is the maximum number.
This function will set the maximum size of all handshake messages.
Handshakes over this size are rejected with
GNUTLS_E_HANDSHAKE_TOO_LARGE error code. The default value is
48kb which is typically large enough. Set this to 0 if you do not
want to set an upper limit.
The reason for restricting the handshake message sizes are to limit Denial of Service attacks.
session: is a gnutls_session_t structure.
func: is the function to be called
This function will set a callback to be called after the client hello has been received (callback valid in server side only). This allows the server to adjust settings based on received extensions.
Those settings could be ciphersuites, requesting certificate, or anything else except for version negotiation (this is done before the hello message is parsed).
This callback must return 0 on success or a gnutls error code to terminate the handshake.
Warning: You should not use this function to terminate the handshake based on client input unless you know what you are doing. Before the handshake is finished there is no way to know if there is a man-in-the-middle attack being performed.
session: is a gnutls_session_t structure.
allow: is an integer (0 or 1)
This function will enable or disable the use of private cipher
suites (the ones that start with 0xFF). By default or if allow is 0 then these cipher suites will not be advertized nor used.
Currently GnuTLS does not include such cipher-suites or compression algorithms.
Enabling the private ciphersuites when talking to other than gnutls servers and clients may cause interoperability problems.
hex_data: string with data in hex format
hex_size: size of hex data
bin_data: output array with binary data
bin_size: when calling should hold maximum size of bin_data ,
on return will hold actual length of bin_data .
Convert a buffer with hex data to binary data.
Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.
Since: 2.4.0
hex_data: contain the encoded data
result: the place where decoded data will be copied
result_size: holds the size of the result
This function will decode the given encoded data, using the hex encoding used by PSK password files.
Note that hex_data should be null terminated.
Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
long enough, or 0 on success.
data: contain the raw data
result: the place where hex data will be copied
result_size: holds the size of the result
This function will convert the given data to printable data, using the hex encoding, as used in the PSK password files.
Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
long enough, or 0 on success.
session: is a pointer to a gnutls_session_t structure.
flags: indicate if this session is to be used for server or client.
This function initializes the current session to null. Every
session must be initialized before use, so internal structures can
be allocated. This function allocates structures which can only
be free’d by calling gnutls_deinit() . Returns GNUTLS_E_SUCCESS (0) on success.
flags can be one of GNUTLS_CLIENT and GNUTLS_SERVER . For a DTLS
entity, the flags GNUTLS_DATAGRAM and GNUTLS_NONBLOCK are
also available. The latter flag will enable a non-blocking
operation of the DTLS timers.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
key: is a pointer to a gnutls_datum_t which will contain a newly
created key.
key_size: The number of bytes of the key.
Generates a random key of key_bytes size.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
Since: 3.0
session: is a gnutls_session_t structure.
Get currently used key exchange algorithm.
Returns: the key exchange algorithm used in the last handshake, a
gnutls_kx_algorithm_t value.
name: is a KX name
Convert a string to a gnutls_kx_algorithm_t value. The names are
compared in a case insensitive way.
Returns: an id of the specified KX algorithm, or GNUTLS_KX_UNKNOWN
on error.
algorithm: is a key exchange algorithm
Convert a gnutls_kx_algorithm_t value to a string.
Returns: a pointer to a string that contains the name of the
specified key exchange algorithm, or NULL .
Get a list of supported key exchange algorithms.
This function is not thread safe.
Returns: a (0)-terminated list of gnutls_kx_algorithm_t integers
indicating the available key exchange algorithms.
session: is a gnutls_session_t structure.
Get currently used MAC algorithm.
Returns: the currently used mac algorithm, a
gnutls_mac_algorithm_t value.
name: is a MAC algorithm name
Convert a string to a gnutls_mac_algorithm_t value. The names are
compared in a case insensitive way.
Returns: a gnutls_mac_algorithm_t id of the specified MAC
algorithm string, or GNUTLS_MAC_UNKNOWN on failures.
algorithm: is an encryption algorithm
Get size of MAC key.
Returns: length (in bytes) of the given MAC key size, or 0 if the given MAC algorithm is invalid.
algorithm: is a MAC algorithm
Convert a gnutls_mac_algorithm_t value to a string.
Returns: a string that contains the name of the specified MAC
algorithm, or NULL .
Get a list of hash algorithms for use as MACs. Note that not necessarily all MACs are supported in TLS cipher suites. For example, MD2 is not supported as a cipher suite, but is supported for other purposes (e.g., X.509 signature verification or similar).
This function is not thread safe.
Returns: Return a (0)-terminated list of gnutls_mac_algorithm_t
integers indicating the available MACs.
session: is a pointer to a gnutls_session_t structure.
status: is one of GNUTLS_OPENPGP_CERT, or GNUTLS_OPENPGP_CERT_FINGERPRINT
This function will order gnutls to send the key fingerprint instead of the key in the initial handshake procedure. This should be used with care and only when there is indication or knowledge that the server can obtain the client’s key.
header: A null terminated string with the PEM header (eg. CERTIFICATE)
b64_data: contain the encoded data
result: the place where decoded data will be copied
result_size: holds the size of the result
This function will decode the given encoded data. If the header given is non null this function will search for "—–BEGIN header" and decode only this part. Otherwise it will decode the first PEM packet found.
Returns: On success GNUTLS_E_SUCCESS (0) is returned,
GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is
not long enough, or 0 on success.
header: The PEM header (eg. CERTIFICATE)
b64_data: contains the encoded data
result: the place where decoded data lie
This function will decode the given encoded data. The decoded data will be allocated, and stored into result. If the header given is non null this function will search for "—–BEGIN header" and decode only this part. Otherwise it will decode the first PEM packet found.
You should use gnutls_free() to free the returned data.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
msg: is a message to be put in the header
data: contain the raw data
result: the place where base64 data will be copied
result_size: holds the size of the result
This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in PEM messages.
The output string will be null terminated, although the size will not include the terminating null.
Returns: On success GNUTLS_E_SUCCESS (0) is returned,
GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is
not long enough, or 0 on success.
msg: is a message to be put in the encoded header
data: contains the raw data
result: will hold the newly allocated encoded data
This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in PEM messages. This function will allocate the required memory to hold the encoded data.
You should use gnutls_free() to free the returned data.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
error: is a GnuTLS error code, a negative error code
This function is like perror() . The only difference is that it
accepts an error number returned by a gnutls function.
algorithm: is a pk algorithm
Convert a gnutls_pk_algorithm_t value to a string.
Returns: a string that contains the name of the specified public
key algorithm, or NULL .
algo: is a public key algorithm
bits: is the number of bits
This is the inverse of gnutls_sec_param_to_pk_bits() . Given an algorithm
and the number of bits, it will return the security parameter. This is
a rough indication.
Returns: The security parameter.
Since: 2.12.0
name: is a string containing a public key algorithm name.
Convert a string to a gnutls_pk_algorithm_t value. The names are
compared in a case insensitive way. For example,
gnutls_pk_get_id("RSA") will return GNUTLS_PK_RSA .
Returns: a gnutls_pk_algorithm_t id of the specified public key
algorithm string, or GNUTLS_PK_UNKNOWN on failures.
Since: 2.6.0
algorithm: is a public key algorithm
Convert a gnutls_pk_algorithm_t value to a string.
Returns: a pointer to a string that contains the name of the
specified public key algorithm, or NULL .
Since: 2.6.0
Get a list of supported public key algorithms.
This function is not thread safe.
Returns: a (0)-terminated list of gnutls_pk_algorithm_t integers
indicating the available ciphers.
Since: 2.6.0
session: is a gnutls_session_t structure.
label_size: length of the label variable.
label: label used in PRF computation, typically a short string.
server_random_first: non-0 if server random field should be first in seed
extra_size: length of the extra variable.
extra: optional extra data to seed the PRF with.
outsize: size of pre-allocated output buffer to hold the output.
out: pre-allocate buffer to hold the generated data.
Apply the TLS Pseudo-Random-Function (PRF) on the master secret and the provided data, seeded with the client and server random fields.
The label variable usually contain a string denoting the purpose
for the generated data. The server_random_first indicate whether
the client random field or the server random field should be first
in the seed. Non-0 indicate that the server random field is first,
0 that the client random field is first.
The extra variable can be used to add more data to the seed, after
the random variables. It can be used to tie make sure the
generated output is strongly connected to some additional data
(e.g., a string used in user authentication).
The output is placed in out , which must be pre-allocated.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
session: is a gnutls_session_t structure.
label_size: length of the label variable.
label: label used in PRF computation, typically a short string.
seed_size: length of the seed variable.
seed: optional extra data to seed the PRF with.
outsize: size of pre-allocated output buffer to hold the output.
out: pre-allocate buffer to hold the generated data.
Apply the TLS Pseudo-Random-Function (PRF) on the master secret and the provided data.
The label variable usually contain a string denoting the purpose
for the generated data. The seed usually contain data such as the
client and server random, perhaps together with some additional
data that is added to guarantee uniqueness of the output for a
particular purpose.
Because the output is not guaranteed to be unique for a particular
session unless seed include the client random and server random
fields (the PRF would output the same data on another connection
resumed from the first one), it is not recommended to use this
function directly. The gnutls_prf() function seed the PRF with the
client and server random fields directly, and is recommended if you
want to generate pseudo random data unique for each session.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
pcache: is a gnutls_prioritity_t structure.
list: will point to an integer list
Get a list of available certificate types in the priority structure.
Returns: the number of certificate types, or an error code.
Since: 3.0
pcache: is a gnutls_prioritity_t structure.
list: will point to an integer list
Get a list of available compression method in the priority structure.
Returns: the number of methods, or an error code.
Since: 3.0
priority_cache: is a gnutls_prioritity_t structure.
Deinitializes the priority cache.
pcache: is a gnutls_prioritity_t structure.
list: will point to an integer list
Get a list of available elliptic curves in the priority structure.
Returns: the number of curves, or an error code.
Since: 3.0
pcache: is a gnutls_prioritity_t structure.
idx: is an index number.
sidx: internal index of cipher suite to get information about.
Provides the internal ciphersuite index to be used with
gnutls_cipher_suite_info() . The index idx provided is an
index kept at the priorities structure. It might be that a valid
priorities index does not correspond to a ciphersuite and in
that case GNUTLS_E_UNKNOWN_CIPHER_SUITE will be returned.
Once the last available index is crossed then
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
Returns: On success it returns GNUTLS_E_SUCCESS (0), or a negative error value otherwise.
priority_cache: is a gnutls_prioritity_t structure.
priorities: is a string describing priorities
err_pos: In case of an error this will have the position in the string the error occured
Sets priorities for the ciphers, key exchange methods, macs and compression methods.
The priorities option allows you to specify a colon
separated list of the cipher priorities to enable.
Some keywords are defined to provide quick access
to common preferences.
"PERFORMANCE" means all the "secure" ciphersuites are enabled, limited to 128 bit ciphers and sorted by terms of speed performance.
"NORMAL" means all "secure" ciphersuites. The 256-bit ciphers are included as a fallback only. The ciphers are sorted by security margin.
"SECURE128" means all "secure" ciphersuites of security level 128-bit or more.
"SECURE192" means all "secure" ciphersuites of security level 192-bit or more.
"SUITEB128" means all the NSA SuiteB ciphersuites with security level of 128.
"SUITEB192" means all the NSA SuiteB ciphersuites with security level of 192.
"EXPORT" means all ciphersuites are enabled, including the low-security 40 bit ciphers.
"NONE" means nothing is enabled. This disables even protocols and compression methods.
Special keywords are "!", "-" and "+". "!" or "-" appended with an algorithm will remove this algorithm. "+" appended with an algorithm will add this algorithm.
Check the GnuTLS manual section "Priority strings" for detailed information.
Examples: "NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL"
"NORMAL:-ARCFOUR-128" means normal ciphers except for ARCFOUR-128.
"SECURE:-VERS-SSL3.0:+COMP-DEFLATE" means that only secure ciphers are enabled, SSL3.0 is disabled, and libz compression enabled.
"NONE:+VERS-TLS-ALL:+AES-128-CBC:+RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1",
"NONE:+VERS-TLS-ALL:+AES-128-CBC:+ECDHE-RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1:+CURVE-SECP256R1",
"NORMAL:COMPAT " is the most compatible mode.
Returns: On syntax error GNUTLS_E_INVALID_REQUEST is returned,
GNUTLS_E_SUCCESS on success, or an error code.
pcache: is a gnutls_prioritity_t structure.
list: will point to an integer list
Get a list of available TLS version numbers in the priority structure.
Returns: the number of protocols, or an error code.
Since: 3.0
session: is a gnutls_session_t structure.
priority: is a gnutls_priority_t structure.
Sets the priorities to use on the ciphers, key exchange methods, macs and compression methods.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
session: is a gnutls_session_t structure.
priorities: is a string describing priorities
err_pos: In case of an error this will have the position in the string the error occured
Sets the priorities to use on the ciphers, key exchange methods,
macs and compression methods. This function avoids keeping a
priority cache and is used to directly set string priorities to a
TLS session. For documentation check the gnutls_priority_init() .
Returns: On syntax error GNUTLS_E_INVALID_REQUEST is returned,
GNUTLS_E_SUCCESS on success, or an error code.
pcache: is a gnutls_prioritity_t structure.
list: will point to an integer list
Get a list of available signature algorithms in the priority structure.
Returns: the number of algorithms, or an error code.
Since: 3.0
name: is a protocol name
The names are compared in a case insensitive way.
Returns: an id of the specified protocol, or
GNUTLS_VERSION_UNKNOWN on error.
version: is a (gnutls) version number
Convert a gnutls_protocol_t value to a string.
Returns: a string that contains the name of the specified TLS
version (e.g., "TLS1.0"), or NULL .
session: is a gnutls_session_t structure.
Get TLS version, a gnutls_protocol_t value.
Returns: The version of the currently used protocol.
Get a list of supported protocols, e.g. SSL 3.0, TLS 1.0 etc.
This function is not thread safe.
Returns: a (0)-terminated list of gnutls_protocol_t integers
indicating the available protocols.
sc: is a pointer to a gnutls_psk_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
sc: is a pointer to a gnutls_psk_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls session
The PSK identity hint may give the client help in deciding which username to use. This should only be called in case of PSK authentication and in case of a client.
Returns: the identity hint of the peer, or NULL in case of an error.
Since: 2.4.0
sc: is a gnutls_psk_client_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
sc: is a gnutls_psk_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
session: is a gnutls session
This should only be called in case of PSK authentication and in case of a server.
Returns: the username of the peer, or NULL in case of an error.
res: is a gnutls_psk_client_credentials_t structure.
username: is the user’s zero-terminated userid
key: is the user’s key
flags: indicate the format of the key, either
GNUTLS_PSK_KEY_RAW or GNUTLS_PSK_KEY_HEX .
This function sets the username and password, in a
gnutls_psk_client_credentials_t structure. Those will be used in
PSK authentication. username should be an ASCII string or UTF-8
strings prepared using the "SASLprep" profile of "stringprep". The
key can be either in raw byte format or in Hex format (without the
0x prefix).
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
cred: is a gnutls_psk_server_credentials_t structure.
func: is the callback function
This function can be used to set a callback to retrieve the username and password for client PSK authentication. The callback’s function form is: int (*callback)(gnutls_session_t, char** username, gnutls_datum_t* key);
The username and key ->data must be allocated using gnutls_malloc() .
username should be ASCII strings or UTF-8 strings prepared using
the "SASLprep" profile of "stringprep".
The callback function will be called once per handshake.
The callback function should return 0 on success. -1 indicates an error.
res: is a gnutls_psk_server_credentials_t structure
func: is the function to be called
This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for PSK authentication. The
callback should return GNUTLS_E_SUCCESS (0) on success.
res: is a gnutls_psk_server_credentials_t structure.
password_file: is the PSK password file (passwd.psk)
This function sets the password file, in a
gnutls_psk_server_credentials_t structure. This password file
holds usernames and keys and will be used for PSK authentication.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
cred: is a gnutls_psk_server_credentials_t structure.
func: is the callback function
This function can be used to set a callback to retrieve the user’s PSK credentials. The callback’s function form is: int (*callback)(gnutls_session_t, const char* username, gnutls_datum_t* key);
username contains the actual username.
The key must be filled in using the gnutls_malloc() .
In case the callback returned a negative number then gnutls will assume that the username does not exist.
The callback function will only be called once per handshake. The callback function should return 0 on success, while -1 indicates an error.
res: is a gnutls_psk_server_credentials_t structure.
hint: is the PSK identity hint string
This function sets the identity hint, in a
gnutls_psk_server_credentials_t structure. This hint is sent to
the client to help it chose a good PSK credential (i.e., username
and password).
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
Since: 2.4.0
res: is a gnutls_psk_server_credentials_t structure
dh_params: is a structure that holds Diffie-Hellman parameters.
This function will set the Diffie-Hellman parameters for an anonymous server to use. These parameters will be used in Diffie-Hellman exchange with PSK cipher suites.
res: is a gnutls_certificate_credentials_t structure
func: is the function to be called
This function will set a callback in order for the server to get
the Diffie-Hellman parameters for PSK authentication. The callback
should return GNUTLS_E_SUCCESS (0) on success.
type: The type of the random art
key_type: The type of the key (RSA, DSA etc.)
key_size: The size of the key in bits
fpr: The fingerprint of the key
fpr_size: The size of the fingerprint
art: The returned random art
This function will convert a given fingerprint to an "artistic"
image. The returned image is allocated using gnutls_malloc()
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
This function checks if there are unread data
in the gnutls buffers. If the return value is
non-zero the next call to gnutls_record_recv()
is guarranteed not to block.
Returns: Returns the size of the data or zero.
session: is a gnutls_session_t structure.
Used to disabled padding in TLS 1.0 and above. Normally you do not need to use this function, but there are buggy clients that complain if a server pads the encrypted data. This of course will disable protection against statistical attacks on the data.
Normally only servers that require maximum compatibility with everything out there, need to call this function.
session: is a gnutls_session_t structure.
This function provides information about the internals of the
record protocol and is only useful if a prior gnutls function call
(e.g. gnutls_handshake() ) was interrupted for some reason, that
is, if a function returned GNUTLS_E_INTERRUPTED or
GNUTLS_E_AGAIN . In such a case, you might want to call select()
or poll() before calling the interrupted gnutls function again. To
tell you whether a file descriptor should be selected for either
reading or writing, gnutls_record_get_direction() returns 0 if the
interrupted function was trying to read data, and 1 if it was
trying to write data.
Returns: 0 if trying to read data, 1 if trying to write data.
session: is a gnutls_session_t structure.
Get the record size. The maximum record size is negotiated by the client after the first handshake message.
Returns: The maximum record packet size in this connection.
session: is a gnutls_session_t structure.
data: the buffer that the data will be read into
data_size: the number of requested bytes
This function has the similar semantics with recv() . The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
In the special case that a server requests a renegotiation, the
client may receive an error code of GNUTLS_E_REHANDSHAKE . This
message may be simply ignored, replied with an alert
GNUTLS_A_NO_RENEGOTIATION , or replied with a new handshake,
depending on the client’s will.
If EINTR is returned by the internal push function (the default
is recv() ) then GNUTLS_E_INTERRUPTED will be returned. If
GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN is returned, you must
call this function again to get the data. See also
gnutls_record_get_direction() .
A server may also receive GNUTLS_E_REHANDSHAKE when a client has
initiated a handshake. In that case the server can only initiate a
handshake or terminate the connection.
Returns: The number of bytes received and zero on EOF (for stream
connections). A negative error code is returned in case of an error.
The number of bytes received might be less than the requested data_size .
session: is a gnutls_session_t structure.
data: the buffer that the data will be read into
data_size: the number of requested bytes
seq: is the packet’s 64-bit sequence number. Should have space for 8 bytes.
This function is the same as gnutls_record_recv() , except that
it returns in addition to data, the sequence number of the data.
This is useful in DTLS where record packets might be received
out-of-order. The returned 8-byte sequence number is an
integer in big-endian format and should be
treated as a unique message identification.
Returns: The number of bytes received and zero on EOF. A negative
error code is returned in case of an error. The number of bytes
received might be less than data_size .
Since: 3.0
session: is a gnutls_session_t structure.
data: contains the data to send
data_size: is the length of the data
This function has the similar semantics with send() . The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
Note that if the send buffer is full, send() will block this
function. See the send() documentation for full information. You
can replace the default push function by using
gnutls_transport_set_ptr2() with a call to send() with a
MSG_DONTWAIT flag if blocking is a problem.
If the EINTR is returned by the internal push function (the
default is send() ) then GNUTLS_E_INTERRUPTED will be returned. If
GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN is returned, you must
call this function again, with the same parameters; alternatively
you could provide a NULL pointer for data, and 0 for
size. cf. gnutls_record_get_direction() .
Returns: The number of bytes sent, or a negative error code. The
number of bytes sent might be less than data_size . The maximum
number of bytes this function can send in a single call depends
on the negotiated maximum record size.
session: is a gnutls_session_t structure.
size: is the new size
This function sets the maximum record packet size in this connection. This property can only be set to clients. The server may choose not to accept the requested size.
Acceptable values are 512(=2^9), 1024(=2^10), 2048(=2^11) and 4096(=2^12). The requested record size does get in effect immediately only while sending data. The receive part will take effect after a successful handshake.
This function uses a TLS extension called ’max record size’. Not all TLS implementations use or even understand this extension.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
session: is a gnutls_session_t structure.
This function will renegotiate security parameters with the client. This should only be called in case of a server.
This message informs the peer that we want to renegotiate parameters (perform a handshake).
If this function succeeds (returns 0), you must call the
gnutls_handshake() function in order to negotiate the new
parameters.
Since TLS is full duplex some application data might have been
sent during peer’s processing of this message. In that case
one should call gnutls_record_recv() until GNUTLS_E_REHANDSHAKE
is returned to clear any pending data. Care must be taken if
rehandshake is mandatory to terminate if it does not start after
some threshold.
If the client does not wish to renegotiate parameters he will
should with an alert message, thus the return code will be
GNUTLS_E_WARNING_ALERT_RECEIVED and the alert will be
GNUTLS_A_NO_RENEGOTIATION . A client may also choose to ignore
this message.
Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.
session: is a gnutls_session_t structure.
Can be used to check whether safe renegotiation is being used in the current session.
Returns: 0 when safe renegotiation is not used and non (0) when safe renegotiation is used.
Since: 2.10.0
param: is a security parameter
Convert a gnutls_sec_param_t value to a string.
Returns: a pointer to a string that contains the name of the
specified security level, or NULL .
Since: 2.12.0
algo: is a public key algorithm
param: is a security parameter
When generating private and public key pairs a difficult question is which size of "bits" the modulus will be in RSA and the group size in DSA. The easy answer is 1024, which is also wrong. This function will convert a human understandable security parameter to an appropriate size for the specific algorithm.
Returns: The number of bits, or (0).
Since: 2.12.0
session: is a gnutls_session_t structure.
data: will hold the data
data_length: will hold the data length. Must hold the maximum size of data.
type: will hold the server name indicator type
indx: is the index of the server_name
This function will allow you to get the name indication (if any), a client has sent. The name indication may be any of the enumeration gnutls_server_name_type_t.
If type is GNUTLS_NAME_DNS, then this function is to be used by
servers that support virtual hosting, and the data will be a null
terminated UTF-8 string.
If data has not enough size to hold the server name
GNUTLS_E_SHORT_MEMORY_BUFFER is returned, and data_length will
hold the required size.
index is used to retrieve more than one server names (if sent by
the client). The first server name has an index of 0, the second 1
and so on. If no name with the given index exists
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
session: is a gnutls_session_t structure.
type: specifies the indicator type
name: is a string that contains the server name.
name_length: holds the length of name
This function is to be used by clients that want to inform (via a TLS extension mechanism) the server of the name they connected to. This should be used by clients that connect to servers that do virtual hosting.
The value of name depends on the type type. In case of
GNUTLS_NAME_DNS , an ASCII (0)-terminated domain name string,
without the trailing dot, is expected. IPv4 or IPv6 addresses are
not permitted.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned,
otherwise a negative error code is returned.
session: is a gnutls_session_t structure.
cbtype: an gnutls_channel_binding_t enumeration type
cb: output buffer array with data
Extract given channel binding data of the cbtype (e.g.,
GNUTLS_CB_TLS_UNIQUE ) type.
Returns: GNUTLS_E_SUCCESS on success,
GNUTLS_E_UNIMPLEMENTED_FEATURE if the cbtype is unsupported,
GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE if the data is not
currently available, or an error code.
Since: 2.12.0
session: is a gnutls_session_t structure.
This function can be used to disable certain (security) features in
TLS in order to maintain maximum compatibility with buggy
clients. It is equivalent to calling:
gnutls_record_disable_padding()
Normally only servers that require maximum compatibility with everything out there, need to call this function.
session: is a gnutls_session_t structure.
session_data: is a pointer to space to hold the session.
session_data_size: is the session_data’s size, or it will be set by the function.
Returns all session parameters, in order to support resuming. The
client should call this, and keep the returned session, if he
wants to resume that current version later by calling
gnutls_session_set_data() This function must be called after a
successful handshake.
Resuming sessions is really useful and speedups connections after a successful one.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
data: is a pointer to a datum that will hold the session.
Returns all session parameters, in order to support resuming. The
client should call this, and keep the returned session, if he wants
to resume that current version later by calling
gnutls_session_set_data() . This function must be called after a
successful handshake. The returned datum must be freed with
gnutls_free() .
Resuming sessions is really useful and speedups connections after a successful one.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
session_id: is a pointer to space to hold the session id.
session_id_size: is the session id’s size, or it will be set by the function.
Returns the current session id. This can be used if you want to check if the next session you tried to resume was actually resumed. This is because resumed sessions have the same sessionID with the original session.
Session id is some data set by the server, that identify the current session. In TLS 1.0 and SSL 3.0 session id is always less than 32 bytes.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
Get user pointer for session. Useful in callbacks. This is the
pointer set with gnutls_session_set_ptr() .
Returns: the user given pointer from the session structure, or
NULL if it was never set.
session: is a gnutls_session_t structure.
client: the client part of the random
server: the server part of the random
This functions returns pointers to the client and server random fields used in the TLS handshake. The pointers are not to be modified or deallocated.
If a client random value has not yet been established, the output will be garbage.
Since: 3.0
session: is a gnutls_session_t structure.
Check whether session is resumed or not.
Returns: non zero if this session is resumed, or a zero if this is a new session.
session: is a gnutls_session_t structure.
Check whether the client has asked for session resumption. This function is valid only on server side.
Returns: non zero if session resumption was asked, or a zero if not.
session: is a gnutls_session_t structure.
session_data: is a pointer to space to hold the session.
session_data_size: is the session’s size
Sets all session parameters, in order to resume a previously
established session. The session data given must be the one
returned by gnutls_session_get_data() . This function should be
called before gnutls_handshake() .
Keep in mind that session resuming is advisory. The server may choose not to resume the session, thus a full handshake will be performed.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
session: is a gnutls_session_t structure.
ptr: is the user pointer
This function will set (associate) the user given pointer ptr to
the session structure. This is pointer can be accessed with
gnutls_session_get_ptr() .
session: is a gnutls_session_t structure.
Request that the client should attempt session resumption using SessionTicket.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
Since: 2.10.0
session: is a gnutls_session_t structure.
key: key to encrypt session parameters.
Request that the server should attempt session resumption using
SessionTicket. key must be initialized with
gnutls_session_ticket_key_generate() .
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
Since: 2.10.0
key: is a pointer to a gnutls_datum_t which will contain a newly
created key.
Generate a random key to encrypt security parameters within SessionTicket.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
Since: 2.10.0
session: is a gnutls_session_t structure.
Sets some default priority on the ciphers, key exchange methods, macs and compression methods.
This is the same as calling:
gnutls_priority_set_direct (session, "NORMAL", NULL);
This function is kept around for backwards compatibility, but
because of its wide use it is still fully supported. If you wish
to allow users to provide a string that specify which ciphers to
use (which is recommended), you should use
gnutls_priority_set_direct() or gnutls_priority_set() instead.
Returns: GNUTLS_E_SUCCESS on success, or an error code.
session: is a gnutls_session_t structure.
indx: is an index of the signature algorithm to return
algo: the returned certificate type will be stored there
Returns the signature algorithm specified by index that was
requested by the peer. If the specified index has no data available
this function returns GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE . If
the negotiated TLS version does not support signature algorithms
then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned even
for the first index. The first index is 0.
This function is useful in the certificate callback functions to assist in selecting the correct certificate.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.
Since: 2.10.0
name: is a MAC algorithm name
The names are compared in a case insensitive way.
Returns: return a gnutls_sign_algorithm_t value corresponding to
the specified cipher, or GNUTLS_SIGN_UNKNOWN on error.
algorithm: is a sign algorithm
Convert a gnutls_sign_algorithm_t value to a string.
Returns: a string that contains the name of the specified sign
algorithm, or NULL .
Get a list of supported public key signature algorithms.
Returns: a (0)-terminated list of gnutls_sign_algorithm_t
integers indicating the available ciphers.
sc: is a pointer to a gnutls_srp_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
sc: is a pointer to a gnutls_srp_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
b64_data: contain the encoded data
result: the place where decoded data will be copied
result_size: holds the size of the result
This function will decode the given encoded data, using the base64 encoding found in libsrp.
Note that b64_data should be null terminated.
Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.
Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
long enough, or 0 on success.
b64_data: contains the encoded data
result: the place where decoded data lie
This function will decode the given encoded data. The decoded data will be allocated, and stored into result. It will decode using the base64 algorithm as used in libsrp.
You should use gnutls_free() to free the returned data.
Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.
Returns: 0 on success, or an error code.
data: contain the raw data
result: the place where base64 data will be copied
result_size: holds the size of the result
This function will convert the given data to printable data, using the base64 encoding, as used in the libsrp. This is the encoding used in SRP password files. If the provided buffer is not long enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.
Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.
Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
long enough, or 0 on success.
data: contains the raw data
result: will hold the newly allocated encoded data
This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in SRP password files. This function will allocate the required memory to hold the encoded data.
You should use gnutls_free() to free the returned data.
Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.
Returns: 0 on success, or an error code.
sc: is a gnutls_srp_client_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
sc: is a gnutls_srp_server_credentials_t structure.
This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.
session: is a gnutls session
This function will return the username of the peer. This should only be called in case of SRP authentication and in case of a server. Returns NULL in case of an error.
Returns: SRP username of the peer, or NULL in case of error.
res: is a gnutls_srp_client_credentials_t structure.
username: is the user’s userid
password: is the user’s password
This function sets the username and password, in a
gnutls_srp_client_credentials_t structure. Those will be used in
SRP authentication. username and password should be ASCII
strings or UTF-8 strings prepared using the "SASLprep" profile of
"stringprep".
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
cred: is a gnutls_srp_server_credentials_t structure.
func: is the callback function
This function can be used to set a callback to retrieve the username and password for client SRP authentication. The callback’s function form is:
int (*callback)(gnutls_session_t, char** username, char**password);
The username and password must be allocated using
gnutls_malloc() . username and password should be ASCII strings
or UTF-8 strings prepared using the "SASLprep" profile of
"stringprep".
The callback function will be called once per handshake before the initial hello message is sent.
The callback should not return a negative error code the second time called, since the handshake procedure will be aborted.
The callback function should return 0 on success. -1 indicates an error.
session: is a gnutls_session_t structure.
bits: is the number of bits
This function sets the minimum accepted number of bits, for use in an SRP key exchange. If zero, the default 2048 bits will be used.
In the client side it sets the minimum accepted number of bits. If
a server sends a prime with less bits than that
GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER will be returned by the
handshake.
This function has no effect in server side.
Since: 2.6.0
res: is a gnutls_srp_server_credentials_t structure.
password_file: is the SRP password file (tpasswd)
password_conf_file: is the SRP password conf file (tpasswd.conf)
This function sets the password files, in a
gnutls_srp_server_credentials_t structure. Those password files
hold usernames and verifiers and will be used for SRP
authentication.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
cred: is a gnutls_srp_server_credentials_t structure.
func: is the callback function
This function can be used to set a callback to retrieve the user’s SRP credentials. The callback’s function form is:
int (*callback)(gnutls_session_t, const char* username, gnutls_datum_t* salt, gnutls_datum_t *verifier, gnutls_datum_t* g, gnutls_datum_t* n);
username contains the actual username.
The salt , verifier , generator and prime must be filled
in using the gnutls_malloc() . For convenience prime and generator may also be one of the static parameters defined in gnutls.h.
In case the callback returned a negative number then gnutls will assume that the username does not exist.
In order to prevent attackers from guessing valid usernames, if a user does not exist, g and n values should be filled in using a random user’s parameters. In that case the callback must return the special value (1).
The callback function will only be called once per handshake. The callback function should return 0 on success, while -1 indicates an error.
username: is the user’s name
password: is the user’s password
salt: should be some randomly generated bytes
generator: is the generator of the group
prime: is the group’s prime
res: where the verifier will be stored.
This function will create an SRP verifier, as specified in
RFC2945. The prime and generator should be one of the static
parameters defined in gnutls/gnutls.h or may be generated.
The verifier will be allocated with gnutls_malloc () and will be stored in
res using binary format.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an
error code.
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.
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 store 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
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 the provided certificate to the list of stored public keys. The key will be considered valid until the provided expiration time.
The store 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.
Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a
negative error value.
Since: 3.0
error: is a GnuTLS error code, a negative error code
This function is similar to strerror. The difference is that it
accepts an error number returned by a gnutls function; In case of
an unknown error a descriptive string is sent instead of NULL .
Error codes are always a negative error code.
Returns: A string explaining the GnuTLS error message.
error: is an error returned by a gnutls function.
Return the GnuTLS error code define as a string. For example, gnutls_strerror_name (GNUTLS_E_DH_PRIME_UNACCEPTABLE) will return the string "GNUTLS_E_DH_PRIME_UNACCEPTABLE".
Returns: A string corresponding to the symbol name of the error code.
Since: 2.6.0
type: is a supplemental data format type
Convert a gnutls_supplemental_data_format_type_t value to a
string.
Returns: a string that contains the name of the specified
supplemental data format type, or NULL for unknown types.
tdb: The structure to be deinitialized
This function will deinitialize a public key trust storage structure.
tdb: The structure 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.
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.
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);
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.
gnutls_tdb_store_func(const char* db_name, const char* host, const char* service, time_t expiration, const gnutls_datum_t* pubkey);
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.
gnutls_tdb_verify_func(const char* db_name, const char* host, const char* service, const gnutls_datum_t* pubkey);
session: is a gnutls_session_t structure.
Used to get the first argument of the transport function (like
PUSH and PULL). This must have been set using
gnutls_transport_set_ptr() .
Returns: The first argument of the transport function.
session: is a gnutls_session_t structure.
recv_ptr: will hold the value for the pull function
send_ptr: will hold the value for the push function
Used to get the arguments of the transport functions (like PUSH
and PULL). These should have been set using
gnutls_transport_set_ptr2() .
session: is a gnutls_session_t structure.
err: error value to store in session-specific errno variable.
Store err in the session-specific errno variable. Useful values
for err is EAGAIN and EINTR, other values are treated will be
treated as real errors in the push/pull function.
This function is useful in replacement push and pull functions set by
gnutls_transport_set_push_function() and
gnutls_transport_set_pull_function() under Windows, where the
replacements may not have access to the same errno variable that is used by GnuTLS (e.g., the application is linked to
msvcr71.dll and gnutls is linked to msvcrt.dll).
session: is a gnutls_session_t structure.
errno_func: a callback function similar to write()
This is the function where you set a function to retrieve errno after a failed push or pull operation.
errno_func is of the form,
int (*gnutls_errno_func)(gnutls_transport_ptr_t);
and should return the errno.
Since: 2.12.0
session: is a gnutls_session_t structure.
ptr: is the value.
Used to set the first argument of the transport function (for push and pull callbacks). In berkeley style sockets this function will set the connection descriptor.
session: is a gnutls_session_t structure.
recv_ptr: is the value for the pull function
send_ptr: is the value for the push function
Used to set the first argument of the transport function (for push and pull callbacks). In berkeley style sockets this function will set the connection descriptor. With this function you can use two different pointers for receiving and sending.
session: is a gnutls_session_t structure.
pull_func: a callback function similar to read()
This is the function where you set a function for gnutls to receive data. Normally, if you use berkeley style sockets, do not need to use this function since the default recv(2) will probably be ok. The callback should return 0 on connection termination, a positive number indicating the number of bytes received, and -1 on error.
gnutls_pull_func is of the form,
ssize_t (*gnutls_pull_func)(gnutls_transport_ptr_t, void*, size_t);
session: is a gnutls_session_t structure.
func: a callback function
This is the function where you set a function for gnutls to know
whether data are ready to be received. It should wait for data a
given time frame in milliseconds. The callback should return 0 on
timeout, a positive number if data can be received, and -1 on error.
You’ll need to override this function if select() is not suitable
for the provided transport calls.
The callback function is used in DTLS only.
gnutls_pull_timeout_func is of the form,
ssize_t (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int ms);
Since: 3.0
session: is a gnutls_session_t structure.
push_func: a callback function similar to write()
This is the function where you set a push function for gnutls to use in order to send data. If you are going to use berkeley style sockets, you do not need to use this function since the default send(2) will probably be ok. Otherwise you should specify this function for gnutls to be able to send data. The callback should return a positive number indicating the bytes sent, and -1 on error.
push_func is of the form,
ssize_t (*gnutls_push_func)(gnutls_transport_ptr_t, const void*, size_t);
session: is a gnutls_session_t structure.
vec_func: a callback function similar to writev()
Using this function you can override the default writev(2)
function for gnutls to send data. Setting this callback
instead of gnutls_transport_set_push_function() is recommended
since it introduces less overhead in the TLS handshake process.
vec_func is of the form,
ssize_t (*gnutls_vec_push_func) (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);
Since: 2.12.0
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 the provided certificate using
a list of stored public keys. The service field if non-NULL should
be a port number.
The retrieve 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.
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
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