GTlsConnection: GIO Reference Manual

## GTlsConnection GTlsConnection — TLS connection type |

## Functions

void | g_tls_connection_set_certificate ()
GTlsCertificate * | g_tls_connection_get_certificate ()
GTlsCertificate * | g_tls_connection_get_peer_certificate ()
GTlsCertificateFlags | g_tls_connection_get_peer_certificate_errors ()
void | g_tls_connection_set_require_close_notify ()
gboolean | g_tls_connection_get_require_close_notify ()
void | g_tls_connection_set_rehandshake_mode ()
GTlsRehandshakeMode | g_tls_connection_get_rehandshake_mode ()
void | g_tls_connection_set_use_system_certdb ()
gboolean | g_tls_connection_get_use_system_certdb ()
GTlsDatabase * | g_tls_connection_get_database ()
void | g_tls_connection_set_database ()
GTlsInteraction * | g_tls_connection_get_interaction ()
void | g_tls_connection_set_interaction ()
gboolean | g_tls_connection_handshake ()
void | g_tls_connection_handshake_async ()
gboolean | g_tls_connection_handshake_finish ()
gboolean | g_tls_connection_emit_accept_certificate ()

## 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

## Signals

gboolean | accept-certificate | Run Last

## Types and Values

| GTlsConnection
enum | GTlsRehandshakeMode

## 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`. | [allow-none]

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`. | [allow-none]
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`. | [allow-none]
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