GDtlsConnection: GIO Reference Manual

## GDtlsConnection GDtlsConnection — DTLS connection type |

## Functions

void | g_dtls_connection_set_certificate ()
GTlsCertificate * | g_dtls_connection_get_certificate ()
GTlsCertificate * | g_dtls_connection_get_peer_certificate ()
GTlsCertificateFlags | g_dtls_connection_get_peer_certificate_errors ()
gboolean | g_dtls_connection_get_channel_binding_data ()
void | g_dtls_connection_set_require_close_notify ()
gboolean | g_dtls_connection_get_require_close_notify ()
void | g_dtls_connection_set_rehandshake_mode ()
GTlsRehandshakeMode | g_dtls_connection_get_rehandshake_mode ()
void | g_dtls_connection_set_advertised_protocols ()
const gchar * | g_dtls_connection_get_negotiated_protocol ()
GTlsDatabase * | g_dtls_connection_get_database ()
void | g_dtls_connection_set_database ()
GTlsInteraction * | g_dtls_connection_get_interaction ()
void | g_dtls_connection_set_interaction ()
gboolean | g_dtls_connection_handshake ()
void | g_dtls_connection_handshake_async ()
gboolean | g_dtls_connection_handshake_finish ()
gboolean | g_dtls_connection_shutdown ()
void | g_dtls_connection_shutdown_async ()
gboolean | g_dtls_connection_shutdown_finish ()
gboolean | g_dtls_connection_close ()
void | g_dtls_connection_close_async ()
gboolean | g_dtls_connection_close_finish ()
gboolean | g_dtls_connection_emit_accept_certificate ()

## Properties

GStrv | advertised-protocols | Read / Write
GDatagramBased * | base-socket | Read / Write / Construct Only
GTlsCertificate * | certificate | Read / Write
GTlsDatabase * | database | Read / Write
GTlsInteraction * | interaction | Read / Write
char * | negotiated-protocol | Read
GTlsCertificate * | peer-certificate | Read
GTlsCertificateFlags | peer-certificate-errors | Read
GTlsRehandshakeMode | rehandshake-mode | Read / Write / Construct
gboolean | require-close-notify | Read / Write / Construct

## Signals

gboolean | accept-certificate | Run Last

## Types and Values

| GDtlsConnection

## Object Hierarchy

        GInterface
        ╰── GDtlsConnection

## Prerequisites

GDtlsConnection requires GDatagramBased and GObject.

## Known Derived Interfaces

GDtlsConnection is required by GDtlsClientConnection and GDtlsServerConnection.

## Includes

    #include <gio/gio.h>

## Description

GDtlsConnection is the base DTLS connection class type, which wraps a GDatagramBased and provides DTLS encryption on top of it. Its subclasses, GDtlsClientConnection and GDtlsServerConnection, implement client-side and server-side DTLS, respectively.

For TLS support, see GTlsConnection.

As DTLS is datagram based, GDtlsConnection implements GDatagramBased, presenting a datagram-socket-like API for the encrypted connection. This operates over a base datagram connection, which is also a GDatagramBased (“base-socket”).

To close a DTLS connection, use `g_dtls_connection_close()`.

Neither GDtlsServerConnection or GDtlsClientConnection set the peer address on their base GDatagramBased if it is a GSocket — it is up to the caller to do that if they wish. If they do not, and `g_socket_close()` is called on the base socket, the GDtlsConnection will not raise a `G_IO_ERROR_NOT_CONNECTED` error on further I/O.

## Functions

### g_dtls_connection_set_certificate ()

    void
    g_dtls_connection_set_certificate (GDtlsConnection *conn,
                                       GTlsCertificate *certificate);

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

For a GDtlsClientConnection, 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_dtls_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_dtls_client_connection_get_accepted_cas()` will return non-`NULL`.)

#### Parameters

conn | a GDtlsConnection |
certificate | the certificate to use for `conn` |

Since: 2.48

### g_dtls_connection_get_certificate ()

    GTlsCertificate *
    g_dtls_connection_get_certificate (GDtlsConnection *conn);

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

#### Parameters

conn | a GDtlsConnection |

#### Returns

`conn` 's certificate, or `NULL`.

[transfer none][nullable]

Since: 2.48

### g_dtls_connection_get_peer_certificate ()

    GTlsCertificate *
    g_dtls_connection_get_peer_certificate
                                   (GDtlsConnection *conn);

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

#### Parameters

conn | a GDtlsConnection |

#### Returns

`conn` 's peer's certificate, or `NULL`.

[transfer none][nullable]

Since: 2.48

### g_dtls_connection_get_peer_certificate_errors ()

    GTlsCertificateFlags
    g_dtls_connection_get_peer_certificate_errors
                                   (GDtlsConnection *conn);

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

#### Parameters

conn | a GDtlsConnection |

#### Returns

`conn` 's peer's certificate errors

Since: 2.48

### g_dtls_connection_get_channel_binding_data ()

    gboolean
    g_dtls_connection_get_channel_binding_data
                                   (GDtlsConnection *conn,
                                    GTlsChannelBindingType type,
                                    GByteArray *data,
                                    GError **error);

Query the TLS backend for TLS channel binding data of `type` for `conn` .

This call retrieves TLS channel binding data as specified in RFC 5056, RFC 5929, and related RFCs. The binding data is returned in `data` . The `data` is resized by the callee using GByteArray buffer management and will be freed when the `data` is destroyed by `g_byte_array_unref()`. If `data` is `NULL`, it will only check whether TLS backend is able to fetch the data (e.g. whether `type` is supported by the TLS backend). It does not guarantee that the data will be available though. That could happen if TLS connection does not support `type` or the binding data is not available yet due to additional negotiation or input required.

#### Parameters

conn | a GDtlsConnection |
type | GTlsChannelBindingType type of data to fetch |
data | GByteArray is filled with the binding data, or `NULL`. | [out callee-allocates][optional][transfer none]
error | a GError pointer, or `NULL` |

#### Returns

`TRUE` on success, `FALSE` otherwise

Since: 2.66

### g_dtls_connection_set_require_close_notify ()

    void
    g_dtls_connection_set_require_close_notify
                                   (GDtlsConnection *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 may be omitted. You can use `g_dtls_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 GDatagramBased, 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_dtls_connection_close_async()` on `conn` itself, 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-socket” rather than closing `conn` itself.

#### Parameters

conn | a GDtlsConnection |
require_close_notify | whether or not to require close notification |

Since: 2.48

### g_dtls_connection_get_require_close_notify ()

    gboolean
    g_dtls_connection_get_require_close_notify
                                   (GDtlsConnection *conn);

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

#### Parameters

conn | a GDtlsConnection |

#### Returns

`TRUE` if `conn` requires a proper TLS close notification.

Since: 2.48

### g_dtls_connection_set_rehandshake_mode ()

    void
    g_dtls_connection_set_rehandshake_mode
                                   (GDtlsConnection *conn,
                                    GTlsRehandshakeMode mode);

`g_dtls_connection_set_rehandshake_mode` has been deprecated since version 2.60. and should not be used in newly-written code.

Changing the rehandshake mode is no longer required for compatibility. Also, rehandshaking has been removed from the TLS protocol in TLS 1.3.

Since GLib 2.64, changing the rehandshake mode is no longer supported and will have no effect. With TLS 1.3, rehandshaking has been removed from the TLS protocol, replaced by separate post-handshake authentication and rekey operations.

#### Parameters

conn | a GDtlsConnection |
mode | the rehandshaking mode |

Since: 2.48

### g_dtls_connection_get_rehandshake_mode ()

    GTlsRehandshakeMode
    g_dtls_connection_get_rehandshake_mode
                                   (GDtlsConnection *conn);

`g_dtls_connection_get_rehandshake_mode` has been deprecated since version 2.64. and should not be used in newly-written code.

Changing the rehandshake mode is no longer required for compatibility. Also, rehandshaking has been removed from the TLS protocol in TLS 1.3.

Gets `conn` rehandshaking mode. See `g_dtls_connection_set_rehandshake_mode()` for details.

#### Parameters

conn | a GDtlsConnection |

#### Returns

`G_TLS_REHANDSHAKE_SAFELY`

Since: 2.48

### g_dtls_connection_set_advertised_protocols ()

    void
    g_dtls_connection_set_advertised_protocols
                                   (GDtlsConnection *conn,
                                    const gchar * const *protocols);

Sets the list of application-layer protocols to advertise that the caller is willing to speak on this connection. The Application-Layer Protocol Negotiation (ALPN) extension will be used to negotiate a compatible protocol with the peer; use `g_dtls_connection_get_negotiated_protocol()` to find the negotiated protocol after the handshake. Specifying `NULL` for the the value of `protocols` will disable ALPN negotiation.

See IANA TLS ALPN Protocol IDs for a list of registered protocol IDs.

#### Parameters

conn | a GDtlsConnection |
protocols | a `NULL`-terminated array of ALPN protocol names (eg, "http/1.1", "h2"), or `NULL`. | [array zero-terminated=1][nullable]

Since: 2.60

### g_dtls_connection_get_negotiated_protocol ()

    const gchar *
    g_dtls_connection_get_negotiated_protocol
                                   (GDtlsConnection *conn);

Gets the name of the application-layer protocol negotiated during the handshake.

If the peer did not use the ALPN extension, or did not advertise a protocol that matched one of `conn` 's protocols, or the TLS backend does not support ALPN, then this will be `NULL`. See `g_dtls_connection_set_advertised_protocols()`.

#### Parameters

conn | a GDtlsConnection |

#### Returns

the negotiated protocol, or `NULL`.

[nullable]

Since: 2.60

### g_dtls_connection_get_database ()

    GTlsDatabase *
    g_dtls_connection_get_database (GDtlsConnection *conn);

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

#### Parameters

conn | a GDtlsConnection |

#### Returns

the certificate database that `conn` uses or `NULL`.

[transfer none][nullable]

Since: 2.48

### g_dtls_connection_set_database ()

    void
    g_dtls_connection_set_database (GDtlsConnection *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 GDtlsConnection |
database | a GTlsDatabase. | [nullable]

Since: 2.48

### g_dtls_connection_get_interaction ()

    GTlsInteraction *
    g_dtls_connection_get_interaction (GDtlsConnection *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][nullable]

Since: 2.48

### g_dtls_connection_set_interaction ()

    void
    g_dtls_connection_set_interaction (GDtlsConnection *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: 2.48

### g_dtls_connection_handshake ()

    gboolean
    g_dtls_connection_handshake (GDtlsConnection *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, GDtlsConnection will handle this for you automatically when you try to send or receive data on the connection. You can call `g_dtls_connection_handshake()` manually if you want to know whether the initial handshake succeeded or failed (as opposed to just immediately trying to use `conn` to read or write, in which case, if it fails, it may not be possible to tell if it failed before or after completing the handshake), but beware that servers may reject client authentication after the handshake has completed, so a successful handshake does not indicate the connection will be usable.

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.

Previously, calling `g_dtls_connection_handshake()` after the initial handshake would trigger a rehandshake; however, this usage was deprecated in GLib 2.60 because rehandshaking was removed from the TLS protocol in TLS 1.3. Since GLib 2.64, calling this function after the initial handshake will no longer do anything.

“accept_certificate” may be emitted during the handshake.

#### Parameters

conn | a GDtlsConnection |
cancellable | a GCancellable, or `NULL`. | [nullable]
error | a GError, or `NULL` |

#### Returns

success or failure

Since: 2.48

### g_dtls_connection_handshake_async ()

    void
    g_dtls_connection_handshake_async (GDtlsConnection *conn,
                                       int io_priority,
                                       GCancellable *cancellable,
                                       GAsyncReadyCallback callback,
                                       gpointer user_data);

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

#### Parameters

conn | a GDtlsConnection |
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: 2.48

### g_dtls_connection_handshake_finish ()

    gboolean
    g_dtls_connection_handshake_finish (GDtlsConnection *conn,
                                        GAsyncResult *result,
                                        GError **error);

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

#### Parameters

conn | a GDtlsConnection |
result | a GAsyncResult. |
error | a GError pointer, or `NULL` |

#### Returns

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

Since: 2.48

### g_dtls_connection_shutdown ()

    gboolean
    g_dtls_connection_shutdown (GDtlsConnection *conn,
                                gboolean shutdown_read,
                                gboolean shutdown_write,
                                GCancellable *cancellable,
                                GError **error);

Shut down part or all of a DTLS connection.

If `shutdown_read` is `TRUE` then the receiving side of the connection is shut down, and further reading is disallowed. Subsequent calls to `g_datagram_based_receive_messages()` will return `G_IO_ERROR_CLOSED`.

If `shutdown_write` is `TRUE` then the sending side of the connection is shut down, and further writing is disallowed. Subsequent calls to `g_datagram_based_send_messages()` will return `G_IO_ERROR_CLOSED`.

It is allowed for both `shutdown_read` and `shutdown_write` to be TRUE — this is equivalent to calling `g_dtls_connection_close()`.

If `cancellable` is cancelled, the GDtlsConnection may be left partially-closed and any pending untransmitted data may be lost. Call `g_dtls_connection_shutdown()` again to complete closing the GDtlsConnection.

#### Parameters

conn | a GDtlsConnection |
shutdown_read | `TRUE` to stop reception of incoming datagrams |
shutdown_write | `TRUE` to stop sending outgoing datagrams |
cancellable | a GCancellable, or `NULL`. | [nullable]
error | a GError, or `NULL` |

#### Returns

`TRUE` on success, `FALSE` otherwise

Since: 2.48

### g_dtls_connection_shutdown_async ()

    void
    g_dtls_connection_shutdown_async (GDtlsConnection *conn,
                                      gboolean shutdown_read,
                                      gboolean shutdown_write,
                                      int io_priority,
                                      GCancellable *cancellable,
                                      GAsyncReadyCallback callback,
                                      gpointer user_data);

Asynchronously shut down part or all of the DTLS connection. See `g_dtls_connection_shutdown()` for more information.

#### Parameters

conn | a GDtlsConnection |
shutdown_read | `TRUE` to stop reception of incoming datagrams |
shutdown_write | `TRUE` to stop sending outgoing datagrams |
io_priority | the I/O priority of the request |
cancellable | a GCancellable, or `NULL`. | [nullable]
callback | callback to call when the shutdown operation is complete |
user_data | the data to pass to the callback function |

Since: 2.48

### g_dtls_connection_shutdown_finish ()

    gboolean
    g_dtls_connection_shutdown_finish (GDtlsConnection *conn,
                                       GAsyncResult *result,
                                       GError **error);

Finish an asynchronous TLS shutdown operation. See `g_dtls_connection_shutdown()` for more information.

#### Parameters

conn | a GDtlsConnection |
result | a GAsyncResult |
error | a GError pointer, or `NULL` |

#### Returns

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

Since: 2.48

### g_dtls_connection_close ()

    gboolean
    g_dtls_connection_close (GDtlsConnection *conn,
                             GCancellable *cancellable,
                             GError **error);

Close the DTLS connection. This is equivalent to calling `g_dtls_connection_shutdown()` to shut down both sides of the connection.

Closing a GDtlsConnection waits for all buffered but untransmitted data to be sent before it completes. It then sends a `close_notify` DTLS alert to the peer and may wait for a `close_notify` to be received from the peer. It does not close the underlying “base-socket”; that must be closed separately.

Once `conn` is closed, all other operations will return `G_IO_ERROR_CLOSED`. Closing a GDtlsConnection multiple times will not return an error.

GDtlsConnections will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

If `cancellable` is cancelled, the GDtlsConnection may be left partially-closed and any pending untransmitted data may be lost. Call `g_dtls_connection_close()` again to complete closing the GDtlsConnection.

#### Parameters

conn | a GDtlsConnection |
cancellable | a GCancellable, or `NULL`. | [nullable]
error | a GError, or `NULL` |

#### Returns

`TRUE` on success, `FALSE` otherwise

Since: 2.48

### g_dtls_connection_close_async ()

    void
    g_dtls_connection_close_async (GDtlsConnection *conn,
                                   int io_priority,
                                   GCancellable *cancellable,
                                   GAsyncReadyCallback callback,
                                   gpointer user_data);

Asynchronously close the DTLS connection. See `g_dtls_connection_close()` for more information.

#### Parameters

conn | a GDtlsConnection |
io_priority | the I/O priority of the request |
cancellable | a GCancellable, or `NULL`. | [nullable]
callback | callback to call when the close operation is complete |
user_data | the data to pass to the callback function |

Since: 2.48

### g_dtls_connection_close_finish ()

    gboolean
    g_dtls_connection_close_finish (GDtlsConnection *conn,
                                    GAsyncResult *result,
                                    GError **error);

Finish an asynchronous TLS close operation. See `g_dtls_connection_close()` for more information.

#### Parameters

conn | a GDtlsConnection |
result | a GAsyncResult |
error | a GError pointer, or `NULL` |

#### Returns

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

Since: 2.48

### g_dtls_connection_emit_accept_certificate ()

    gboolean
    g_dtls_connection_emit_accept_certificate
                                   (GDtlsConnection *conn,
                                    GTlsCertificate *peer_cert,
                                    GTlsCertificateFlags errors);

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

#### Parameters

conn | a GDtlsConnection |
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: 2.48

## Types and Values

### GDtlsConnection

    typedef struct _GDtlsConnection GDtlsConnection;

Abstract base class for the backend-specific GDtlsClientConnection and GDtlsServerConnection types.

Since: 2.48

## Property Details

### The `“advertised-protocols”` property

      “advertised-protocols”     GStrv

The list of application-layer protocols that the connection advertises that it is willing to speak. See `g_dtls_connection_set_advertised_protocols()`.

[nullable]

Owner: GDtlsConnection

Flags: Read / Write

Since: 2.60

### The `“base-socket”` property

      “base-socket”              GDatagramBased *

The GDatagramBased that the connection wraps. Note that this may be any implementation of GDatagramBased, not just a GSocket.

Owner: GDtlsConnection

Flags: Read / Write / Construct Only

Since: 2.48

### The `“certificate”` property

      “certificate”              GTlsCertificate *

The connection's certificate; see `g_dtls_connection_set_certificate()`.

Owner: GDtlsConnection

Flags: Read / Write

Since: 2.48

### 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()`.

[nullable]

Owner: GDtlsConnection

Flags: Read / Write

Since: 2.48

### 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.

[nullable]

Owner: GDtlsConnection

Flags: Read / Write

Since: 2.48

### The `“negotiated-protocol”` property

      “negotiated-protocol”      char *

The application-layer protocol negotiated during the TLS handshake. See `g_dtls_connection_get_negotiated_protocol()`.

Owner: GDtlsConnection

Flags: Read

Default value: NULL

Since: 2.60

### The `“peer-certificate”` property

      “peer-certificate”         GTlsCertificate *

The connection's peer's certificate, after the TLS handshake has completed or failed. 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.)

[nullable]

Owner: GDtlsConnection

Flags: Read

Since: 2.48

### The `“peer-certificate-errors”` property

      “peer-certificate-errors”  GTlsCertificateFlags

The errors noticed 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.

Owner: GDtlsConnection

Flags: Read

Since: 2.48

### The `“rehandshake-mode”` property

      “rehandshake-mode”         GTlsRehandshakeMode

The rehandshaking mode. See `g_dtls_connection_set_rehandshake_mode()`.

`GDtlsConnection:rehandshake-mode` has been deprecated since version 2.60 and should not be used in newly-written code.

The rehandshake mode is ignored.

Owner: GDtlsConnection

Flags: Read / Write / Construct

Default value: G_TLS_REHANDSHAKE_NEVER

Since: 2.48

### The `“require-close-notify”` property

      “require-close-notify”     gboolean

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

Owner: GDtlsConnection

Flags: Read / Write / Construct

Default value: TRUE

Since: 2.48

## Signal Details

### The `“accept-certificate”` signal

    gboolean
    user_function (GDtlsConnection     *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_BAD_CERTIFICATE`, 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 GDtlsConnection |
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: 2.48