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GTlsConnection

GTlsConnection — TLS connection type

Properties

GIOStream * base-io-stream Read / Write / Construct Only
GTlsCertificate * certificate Read / Write
GTlsDatabase * database Read / Write
GTlsInteraction * interaction Read / Write
GTlsCertificate * peer-certificate Read
GTlsCertificateFlags peer-certificate-errors Read
GTlsRehandshakeMode rehandshake-mode Read / Write / Construct
gboolean require-close-notify Read / Write / Construct
gboolean use-system-certdb Read / Write / Construct

Types and Values

Object Hierarchy

    GObject
    ╰── GIOStream
        ╰── GTlsConnection

Known Derived Interfaces

GTlsConnection is required by GTlsClientConnection and GTlsServerConnection.

Includes

#include <gio/gio.h>

Description

GTlsConnection is the base TLS connection class type, which wraps a GIOStream and provides TLS encryption on top of it. Its subclasses, GTlsClientConnection and GTlsServerConnection, implement client-side and server-side TLS, respectively.

For DTLS (Datagram TLS) support, see GDtlsConnection.

Functions

g_tls_connection_set_certificate ()

void
g_tls_connection_set_certificate (GTlsConnection *conn,
                                  GTlsCertificate *certificate);

This sets the certificate that conn will present to its peer during the TLS handshake. For a GTlsServerConnection, it is mandatory to set this, and that will normally be done at construct time.

For a GTlsClientConnection, this is optional. If a handshake fails with G_TLS_ERROR_CERTIFICATE_REQUIRED, that means that the server requires a certificate, and if you try connecting again, you should call this method first. You can call g_tls_client_connection_get_accepted_cas() on the failed connection to get a list of Certificate Authorities that the server will accept certificates from.

(It is also possible that a server will allow the connection with or without a certificate; in that case, if you don't provide a certificate, you can tell that the server requested one by the fact that g_tls_client_connection_get_accepted_cas() will return non-NULL.)

Parameters

conn

a GTlsConnection

 

certificate

the certificate to use for conn

 

Since: 2.28


g_tls_connection_get_certificate ()

GTlsCertificate *
g_tls_connection_get_certificate (GTlsConnection *conn);

Gets conn 's certificate, as set by g_tls_connection_set_certificate().

Parameters

conn

a GTlsConnection

 

Returns

conn 's certificate, or NULL.

[transfer none]

Since: 2.28


g_tls_connection_get_peer_certificate ()

GTlsCertificate *
g_tls_connection_get_peer_certificate (GTlsConnection *conn);

Gets conn 's peer's certificate after the handshake has completed. (It is not set during the emission of “accept-certificate”.)

Parameters

conn

a GTlsConnection

 

Returns

conn 's peer's certificate, or NULL.

[transfer none]

Since: 2.28


g_tls_connection_get_peer_certificate_errors ()

GTlsCertificateFlags
g_tls_connection_get_peer_certificate_errors
                               (GTlsConnection *conn);

Gets the errors associated with validating conn 's peer's certificate, after the handshake has completed. (It is not set during the emission of “accept-certificate”.)

Parameters

conn

a GTlsConnection

 

Returns

conn 's peer's certificate errors

Since: 2.28


g_tls_connection_set_require_close_notify ()

void
g_tls_connection_set_require_close_notify
                               (GTlsConnection *conn,
                                gboolean require_close_notify);

Sets whether or not conn expects a proper TLS close notification before the connection is closed. If this is TRUE (the default), then conn will expect to receive a TLS close notification from its peer before the connection is closed, and will return a G_TLS_ERROR_EOF error if the connection is closed without proper notification (since this may indicate a network error, or man-in-the-middle attack).

In some protocols, the application will know whether or not the connection was closed cleanly based on application-level data (because the application-level data includes a length field, or is somehow self-delimiting); in this case, the close notify is redundant and sometimes omitted. (TLS 1.1 explicitly allows this; in TLS 1.0 it is technically an error, but often done anyway.) You can use g_tls_connection_set_require_close_notify() to tell conn to allow an "unannounced" connection close, in which case the close will show up as a 0-length read, as in a non-TLS GSocketConnection, and it is up to the application to check that the data has been fully received.

Note that this only affects the behavior when the peer closes the connection; when the application calls g_io_stream_close() itself on conn , this will send a close notification regardless of the setting of this property. If you explicitly want to do an unclean close, you can close conn 's “base-io-stream” rather than closing conn itself, but note that this may only be done when no other operations are pending on conn or the base I/O stream.

Parameters

conn

a GTlsConnection

 

require_close_notify

whether or not to require close notification

 

Since: 2.28


g_tls_connection_get_require_close_notify ()

gboolean
g_tls_connection_get_require_close_notify
                               (GTlsConnection *conn);

Tests whether or not conn expects a proper TLS close notification when the connection is closed. See g_tls_connection_set_require_close_notify() for details.

Parameters

conn

a GTlsConnection

 

Returns

TRUE if conn requires a proper TLS close notification.

Since: 2.28


g_tls_connection_set_rehandshake_mode ()

void
g_tls_connection_set_rehandshake_mode (GTlsConnection *conn,
                                       GTlsRehandshakeMode mode);

Sets how conn behaves with respect to rehandshaking requests.

G_TLS_REHANDSHAKE_NEVER means that it will never agree to rehandshake after the initial handshake is complete. (For a client, this means it will refuse rehandshake requests from the server, and for a server, this means it will close the connection with an error if the client attempts to rehandshake.)

G_TLS_REHANDSHAKE_SAFELY means that the connection will allow a rehandshake only if the other end of the connection supports the TLS renegotiation_info extension. This is the default behavior, but means that rehandshaking will not work against older implementations that do not support that extension.

G_TLS_REHANDSHAKE_UNSAFELY means that the connection will allow rehandshaking even without the renegotiation_info extension. On the server side in particular, this is not recommended, since it leaves the server open to certain attacks. However, this mode is necessary if you need to allow renegotiation with older client software.

Parameters

conn

a GTlsConnection

 

mode

the rehandshaking mode

 

Since: 2.28


g_tls_connection_get_rehandshake_mode ()

GTlsRehandshakeMode
g_tls_connection_get_rehandshake_mode (GTlsConnection *conn);

Gets conn rehandshaking mode. See g_tls_connection_set_rehandshake_mode() for details.

Parameters

conn

a GTlsConnection

 

Returns

conn 's rehandshaking mode

Since: 2.28


g_tls_connection_set_use_system_certdb ()

void
g_tls_connection_set_use_system_certdb
                               (GTlsConnection *conn,
                                gboolean use_system_certdb);

g_tls_connection_set_use_system_certdb has been deprecated since version 2.30 and should not be used in newly-written code.

Use g_tls_connection_set_database() instead

Sets whether conn uses the system certificate database to verify peer certificates. This is TRUE by default. If set to FALSE, then peer certificate validation will always set the G_TLS_CERTIFICATE_UNKNOWN_CA error (meaning “accept-certificate” will always be emitted on client-side connections, unless that bit is not set in “validation-flags”).

Parameters

conn

a GTlsConnection

 

use_system_certdb

whether to use the system certificate database

 

g_tls_connection_get_use_system_certdb ()

gboolean
g_tls_connection_get_use_system_certdb
                               (GTlsConnection *conn);

g_tls_connection_get_use_system_certdb has been deprecated since version 2.30 and should not be used in newly-written code.

Use g_tls_connection_get_database() instead

Gets whether conn uses the system certificate database to verify peer certificates. See g_tls_connection_set_use_system_certdb().

Parameters

conn

a GTlsConnection

 

Returns

whether conn uses the system certificate database


g_tls_connection_get_database ()

GTlsDatabase *
g_tls_connection_get_database (GTlsConnection *conn);

Gets the certificate database that conn uses to verify peer certificates. See g_tls_connection_set_database().

Parameters

conn

a GTlsConnection

 

Returns

the certificate database that conn uses or NULL.

[transfer none]

Since: 2.30


g_tls_connection_set_database ()

void
g_tls_connection_set_database (GTlsConnection *conn,
                               GTlsDatabase *database);

Sets the certificate database that is used to verify peer certificates. This is set to the default database by default. See g_tls_backend_get_default_database(). If set to NULL, then peer certificate validation will always set the G_TLS_CERTIFICATE_UNKNOWN_CA error (meaning “accept-certificate” will always be emitted on client-side connections, unless that bit is not set in “validation-flags”).

Parameters

conn

a GTlsConnection

 

database

a GTlsDatabase

 

Since: 2.30


g_tls_connection_get_interaction ()

GTlsInteraction *
g_tls_connection_get_interaction (GTlsConnection *conn);

Get the object that will be used to interact with the user. It will be used for things like prompting the user for passwords. If NULL is returned, then no user interaction will occur for this connection.

Parameters

conn

a connection

 

Returns

The interaction object.

[transfer none]

Since: 2.30


g_tls_connection_set_interaction ()

void
g_tls_connection_set_interaction (GTlsConnection *conn,
                                  GTlsInteraction *interaction);

Set the object that will be used to interact with the user. It will be used for things like prompting the user for passwords.

The interaction argument will normally be a derived subclass of GTlsInteraction. NULL can also be provided if no user interaction should occur for this connection.

Parameters

conn

a connection

 

interaction

an interaction object, or NULL.

[nullable]

Since: 2.30


g_tls_connection_handshake ()

gboolean
g_tls_connection_handshake (GTlsConnection *conn,
                            GCancellable *cancellable,
                            GError **error);

Attempts a TLS handshake on conn .

On the client side, it is never necessary to call this method; although the connection needs to perform a handshake after connecting (or after sending a "STARTTLS"-type command) and may need to rehandshake later if the server requests it, GTlsConnection will handle this for you automatically when you try to send or receive data on the connection. However, you can call g_tls_connection_handshake() manually if you want to know for sure whether the initial handshake succeeded or failed (as opposed to just immediately trying to write to conn 's output stream, in which case if it fails, it may not be possible to tell if it failed before or after completing the handshake).

Likewise, on the server side, although a handshake is necessary at the beginning of the communication, you do not need to call this function explicitly unless you want clearer error reporting. However, you may call g_tls_connection_handshake() later on to renegotiate parameters (encryption methods, etc) with the client.

“accept_certificate” may be emitted during the handshake.

Parameters

conn

a GTlsConnection

 

cancellable

a GCancellable, or NULL.

[nullable]

error

a GError, or NULL

 

Returns

success or failure

Since: 2.28


g_tls_connection_handshake_async ()

void
g_tls_connection_handshake_async (GTlsConnection *conn,
                                  int io_priority,
                                  GCancellable *cancellable,
                                  GAsyncReadyCallback callback,
                                  gpointer user_data);

Asynchronously performs a TLS handshake on conn . See g_tls_connection_handshake() for more information.

Parameters

conn

a GTlsConnection

 

io_priority

the I/O priority of the request

 

cancellable

a GCancellable, or NULL.

[nullable]

callback

callback to call when the handshake is complete

 

user_data

the data to pass to the callback function

 

Since: 2.28


g_tls_connection_handshake_finish ()

gboolean
g_tls_connection_handshake_finish (GTlsConnection *conn,
                                   GAsyncResult *result,
                                   GError **error);

Finish an asynchronous TLS handshake operation. See g_tls_connection_handshake() for more information.

Parameters

conn

a GTlsConnection

 

result

a GAsyncResult.

 

error

a GError pointer, or NULL

 

Returns

TRUE on success, FALSE on failure, in which case error will be set.

Since: 2.28


g_tls_connection_emit_accept_certificate ()

gboolean
g_tls_connection_emit_accept_certificate
                               (GTlsConnection *conn,
                                GTlsCertificate *peer_cert,
                                GTlsCertificateFlags errors);

Used by GTlsConnection implementations to emit the “accept-certificate” signal.

Parameters

conn

a GTlsConnection

 

peer_cert

the peer's GTlsCertificate

 

errors

the problems with peer_cert

 

Returns

TRUE if one of the signal handlers has returned TRUE to accept peer_cert

Since: 2.28

Types and Values

GTlsConnection

typedef struct _GTlsConnection GTlsConnection;

Abstract base class for the backend-specific GTlsClientConnection and GTlsServerConnection types.

Since: 2.28


enum GTlsRehandshakeMode

When to allow rehandshaking. See g_tls_connection_set_rehandshake_mode().

Members

G_TLS_REHANDSHAKE_NEVER

Never allow rehandshaking

 

G_TLS_REHANDSHAKE_SAFELY

Allow safe rehandshaking only

 

G_TLS_REHANDSHAKE_UNSAFELY

Allow unsafe rehandshaking

 

Since: 2.28

Property Details

The “base-io-stream” property

  “base-io-stream”           GIOStream *

The GIOStream that the connection wraps. The connection holds a reference to this stream, and may run operations on the stream from other threads throughout its lifetime. Consequently, after the GIOStream has been constructed, application code may only run its own operations on this stream when no GIOStream operations are running.

Flags: Read / Write / Construct Only

Since: 2.28


The “certificate” property

  “certificate”              GTlsCertificate *

The connection's certificate; see g_tls_connection_set_certificate().

Flags: Read / Write

Since: 2.28


The “database” property

  “database”                 GTlsDatabase *

The certificate database to use when verifying this TLS connection. If no certificate database is set, then the default database will be used. See g_tls_backend_get_default_database().

Flags: Read / Write

Since: 2.30


The “interaction” property

  “interaction”              GTlsInteraction *

A GTlsInteraction object to be used when the connection or certificate database need to interact with the user. This will be used to prompt the user for passwords where necessary.

Flags: Read / Write

Since: 2.30


The “peer-certificate” property

  “peer-certificate”         GTlsCertificate *

The connection's peer's certificate, after the TLS handshake has completed and the certificate has been accepted. Note in particular that this is not yet set during the emission of “accept-certificate”.

(You can watch for a “notify” signal on this property to detect when a handshake has occurred.)

Flags: Read

Since: 2.28


The “peer-certificate-errors” property

  “peer-certificate-errors”  GTlsCertificateFlags

The errors noticed-and-ignored while verifying “peer-certificate”. Normally this should be 0, but it may not be if “validation-flags” is not G_TLS_CERTIFICATE_VALIDATE_ALL, or if “accept-certificate” overrode the default behavior.

Flags: Read

Since: 2.28


The “rehandshake-mode” property

  “rehandshake-mode”         GTlsRehandshakeMode

The rehandshaking mode. See g_tls_connection_set_rehandshake_mode().

Flags: Read / Write / Construct

Default value: G_TLS_REHANDSHAKE_SAFELY

Since: 2.28


The “require-close-notify” property

  “require-close-notify”     gboolean

Whether or not proper TLS close notification is required. See g_tls_connection_set_require_close_notify().

Flags: Read / Write / Construct

Default value: TRUE

Since: 2.28


The “use-system-certdb” property

  “use-system-certdb”        gboolean

Whether or not the system certificate database will be used to verify peer certificates. See g_tls_connection_set_use_system_certdb().

GTlsConnection:use-system-certdb has been deprecated since version 2.30 and should not be used in newly-written code.

Use GTlsConnection:database instead

Flags: Read / Write / Construct

Default value: TRUE

Signal Details

The “accept-certificate” signal

gboolean
user_function (GTlsConnection      *conn,
               GTlsCertificate     *peer_cert,
               GTlsCertificateFlags errors,
               gpointer             user_data)

Emitted during the TLS handshake after the peer certificate has been received. You can examine peer_cert 's certification path by calling g_tls_certificate_get_issuer() on it.

For a client-side connection, peer_cert is the server's certificate, and the signal will only be emitted if the certificate was not acceptable according to conn 's “validation_flags”. If you would like the certificate to be accepted despite errors , return TRUE from the signal handler. Otherwise, if no handler accepts the certificate, the handshake will fail with G_TLS_ERROR_BAD_CERTIFICATE.

For a server-side connection, peer_cert is the certificate presented by the client, if this was requested via the server's “authentication_mode”. On the server side, the signal is always emitted when the client presents a certificate, and the certificate will only be accepted if a handler returns TRUE.

Note that if this signal is emitted as part of asynchronous I/O in the main thread, then you should not attempt to interact with the user before returning from the signal handler. If you want to let the user decide whether or not to accept the certificate, you would have to return FALSE from the signal handler on the first attempt, and then after the connection attempt returns a G_TLS_ERROR_HANDSHAKE, you can interact with the user, and if the user decides to accept the certificate, remember that fact, create a new connection, and return TRUE from the signal handler the next time.

If you are doing I/O in another thread, you do not need to worry about this, and can simply block in the signal handler until the UI thread returns an answer.

Parameters

conn

a GTlsConnection

 

peer_cert

the peer's GTlsCertificate

 

errors

the problems with peer_cert .

 

user_data

user data set when the signal handler was connected.

 

Returns

TRUE to accept peer_cert (which will also immediately end the signal emission). FALSE to allow the signal emission to continue, which will cause the handshake to fail if no one else overrides it.

Flags: Run Last

Since: 2.28

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