### Signal

# Gio TlsConnection::accept-certificate

since: 2.28

#### Declaration

    gboolean
    accept_certificate (
      GTlsConnection* self,
      GTlsCertificate* peer_cert,
      GTlsCertificateFlags errors,
      gpointer user_data
    )

#### Description

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 `GTlsClientConnection: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`.

GLib guarantees that if certificate verification fails, this signal will be emitted with at least one error will be set in `errors`, but it does not guarantee that all possible errors will be set. Accordingly, you may not safely decide to ignore any particular type of error. For example, it would be incorrect to ignore `G_TLS_CERTIFICATE_EXPIRED` if you want to allow expired certificates, because this could potentially be the only error flag set even if other problems exist with the certificate.

For a server-side connection, `peer_cert` is the certificate presented by the client, if this was requested via the server’s `GTlsServerConnection: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.

Default handler: The default handler is called after the handlers added via `g_signal_connect()`.
Available since: 2.28

#### Parameters

`peer_cert`

  Type: `GTlsCertificate`

  The peer’s `GTlsCertificate`.

  The data is owned by the caller of the function.

`errors`

  Type: `GTlsCertificateFlags`

  The problems with `peer_cert`.

#### Return value

Type: `gboolean`

`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.