request_filesystem_credentials() WordPress Function

function request_filesystem_credentials( $form_post, $type = '', $error = false, $context = '', $extra_fields = null, $allow_relaxed_file_ownership = false ) {
	global $pagenow;

	/**
	 * Filters the filesystem credentials.
	 *
	 * Returning anything other than an empty string will effectively short-circuit
	 * output of the filesystem credentials form, returning that value instead.
	 *
	 * A filter should return true if no filesystem credentials are required, false if they are required but have not been
	 * provided, or an array of credentials if they are required and have been provided.
	 *
	 * @since 2.5.0
	 * @since 4.6.0 The `$context` parameter default changed from `false` to an empty string.
	 *
	 * @param mixed         $credentials                  Credentials to return instead. Default empty string.
	 * @param string        $form_post                    The URL to post the form to.
	 * @param string        $type                         Chosen type of filesystem.
	 * @param bool|WP_Error $error                        Whether the current request has failed to connect,
	 *                                                    or an error object.
	 * @param string        $context                      Full path to the directory that is tested for
	 *                                                    being writable.
	 * @param array         $extra_fields                 Extra POST fields.
	 * @param bool          $allow_relaxed_file_ownership Whether to allow Group/World writable.
	 */
	$req_cred = apply_filters( 'request_filesystem_credentials', '', $form_post, $type, $error, $context, $extra_fields, $allow_relaxed_file_ownership );

	if ( '' !== $req_cred ) {
		return $req_cred;
	}

	if ( empty( $type ) ) {
		$type = get_filesystem_method( array(), $context, $allow_relaxed_file_ownership );
	}

	if ( 'direct' === $type ) {
		return true;
	}

	if ( is_null( $extra_fields ) ) {
		$extra_fields = array( 'version', 'locale' );
	}

	$credentials = get_option(
		'ftp_credentials',
		array(
			'hostname' => '',
			'username' => '',
		)
	);

	$submitted_form = wp_unslash( $_POST );

	// Verify nonce, or unset submitted form field values on failure.
	if ( ! isset( $_POST['_fs_nonce'] ) || ! wp_verify_nonce( $_POST['_fs_nonce'], 'filesystem-credentials' ) ) {
		unset(
			$submitted_form['hostname'],
			$submitted_form['username'],
			$submitted_form['password'],
			$submitted_form['public_key'],
			$submitted_form['private_key'],
			$submitted_form['connection_type']
		);
	}

	$ftp_constants = array(
		'hostname'    => 'FTP_HOST',
		'username'    => 'FTP_USER',
		'password'    => 'FTP_PASS',
		'public_key'  => 'FTP_PUBKEY',
		'private_key' => 'FTP_PRIKEY',
	);

	// If defined, set it to that. Else, if POST'd, set it to that. If not, set it to an empty string.
	// Otherwise, keep it as it previously was (saved details in option).
	foreach ( $ftp_constants as $key => $constant ) {
		if ( defined( $constant ) ) {
			$credentials[ $key ] = constant( $constant );
		} elseif ( ! empty( $submitted_form[ $key ] ) ) {
			$credentials[ $key ] = $submitted_form[ $key ];
		} elseif ( ! isset( $credentials[ $key ] ) ) {
			$credentials[ $key ] = '';
		}
	}

	// Sanitize the hostname, some people might pass in odd data.
	$credentials['hostname'] = preg_replace( '|\w+://|', '', $credentials['hostname'] ); // Strip any schemes off.

	if ( strpos( $credentials['hostname'], ':' ) ) {
		list( $credentials['hostname'], $credentials['port'] ) = explode( ':', $credentials['hostname'], 2 );
		if ( ! is_numeric( $credentials['port'] ) ) {
			unset( $credentials['port'] );
		}
	} else {
		unset( $credentials['port'] );
	}

	if ( ( defined( 'FTP_SSH' ) && FTP_SSH ) || ( defined( 'FS_METHOD' ) && 'ssh2' === FS_METHOD ) ) {
		$credentials['connection_type'] = 'ssh';
	} elseif ( ( defined( 'FTP_SSL' ) && FTP_SSL ) && 'ftpext' === $type ) { // Only the FTP Extension understands SSL.
		$credentials['connection_type'] = 'ftps';
	} elseif ( ! empty( $submitted_form['connection_type'] ) ) {
		$credentials['connection_type'] = $submitted_form['connection_type'];
	} elseif ( ! isset( $credentials['connection_type'] ) ) { // All else fails (and it's not defaulted to something else saved), default to FTP.
		$credentials['connection_type'] = 'ftp';
	}

	if ( ! $error
		&& ( ! empty( $credentials['hostname'] ) && ! empty( $credentials['username'] ) && ! empty( $credentials['password'] )
			|| 'ssh' === $credentials['connection_type'] && ! empty( $credentials['public_key'] ) && ! empty( $credentials['private_key'] )
		)
	) {
		$stored_credentials = $credentials;

		if ( ! empty( $stored_credentials['port'] ) ) { // Save port as part of hostname to simplify above code.
			$stored_credentials['hostname'] .= ':' . $stored_credentials['port'];
		}

		unset(
			$stored_credentials['password'],
			$stored_credentials['port'],
			$stored_credentials['private_key'],
			$stored_credentials['public_key']
		);

		if ( ! wp_installing() ) {
			update_option( 'ftp_credentials', $stored_credentials );
		}

		return $credentials;
	}

	$hostname        = isset( $credentials['hostname'] ) ? $credentials['hostname'] : '';
	$username        = isset( $credentials['username'] ) ? $credentials['username'] : '';
	$public_key      = isset( $credentials['public_key'] ) ? $credentials['public_key'] : '';
	$private_key     = isset( $credentials['private_key'] ) ? $credentials['private_key'] : '';
	$port            = isset( $credentials['port'] ) ? $credentials['port'] : '';
	$connection_type = isset( $credentials['connection_type'] ) ? $credentials['connection_type'] : '';

	if ( $error ) {
		$error_string = __( '<strong>Error</strong>: Could not connect to the server. Please verify the settings are correct.' );
		if ( is_wp_error( $error ) ) {
			$error_string = esc_html( $error->get_error_message() );
		}
		echo '<div id="message" class="error"><p>' . $error_string . '</p></div>';
	}

	$types = array();
	if ( extension_loaded( 'ftp' ) || extension_loaded( 'sockets' ) || function_exists( 'fsockopen' ) ) {
		$types['ftp'] = __( 'FTP' );
	}
	if ( extension_loaded( 'ftp' ) ) { // Only this supports FTPS.
		$types['ftps'] = __( 'FTPS (SSL)' );
	}
	if ( extension_loaded( 'ssh2' ) ) {
		$types['ssh'] = __( 'SSH2' );
	}

	/**
	 * Filters the connection types to output to the filesystem credentials form.
	 *
	 * @since 2.9.0
	 * @since 4.6.0 The `$context` parameter default changed from `false` to an empty string.
	 *
	 * @param string[]      $types       Types of connections.
	 * @param array         $credentials Credentials to connect with.
	 * @param string        $type        Chosen filesystem method.
	 * @param bool|WP_Error $error       Whether the current request has failed to connect,
	 *                                   or an error object.
	 * @param string        $context     Full path to the directory that is tested for being writable.
	 */
	$types = apply_filters( 'fs_ftp_connection_types', $types, $credentials, $type, $error, $context );
	?>
<form action="<?php echo esc_url( $form_post ); ?>" method="post">
<div id="request-filesystem-credentials-form" class="request-filesystem-credentials-form">
	<?php
	// Print a H1 heading in the FTP credentials modal dialog, default is a H2.
	$heading_tag = 'h2';
	if ( 'plugins.php' === $pagenow || 'plugin-install.php' === $pagenow ) {
		$heading_tag = 'h1';
	}
	echo "<$heading_tag id='request-filesystem-credentials-title'>" . __( 'Connection Information' ) . "</$heading_tag>";
	?>
<p id="request-filesystem-credentials-desc">
	<?php
	$label_user = __( 'Username' );
	$label_pass = __( 'Password' );
	_e( 'To perform the requested action, WordPress needs to access your web server.' );
	echo ' ';
	if ( ( isset( $types['ftp'] ) || isset( $types['ftps'] ) ) ) {
		if ( isset( $types['ssh'] ) ) {
			_e( 'Please enter your FTP or SSH credentials to proceed.' );
			$label_user = __( 'FTP/SSH Username' );
			$label_pass = __( 'FTP/SSH Password' );
		} else {
			_e( 'Please enter your FTP credentials to proceed.' );
			$label_user = __( 'FTP Username' );
			$label_pass = __( 'FTP Password' );
		}
		echo ' ';
	}
	_e( 'If you do not remember your credentials, you should contact your web host.' );

	$hostname_value = esc_attr( $hostname );
	if ( ! empty( $port ) ) {
		$hostname_value .= ":$port";
	}

	$password_value = '';
	if ( defined( 'FTP_PASS' ) ) {
		$password_value = '*****';
	}
	?>
</p>
<label for="hostname">
	<span class="field-title"><?php _e( 'Hostname' ); ?></span>
	<input name="hostname" type="text" id="hostname" aria-describedby="request-filesystem-credentials-desc" class="code" placeholder="<?php esc_attr_e( 'example: www.wordpress.org' ); ?>" value="<?php echo $hostname_value; ?>"<?php disabled( defined( 'FTP_HOST' ) ); ?> />
</label>
<div class="ftp-username">
	<label for="username">
		<span class="field-title"><?php echo $label_user; ?></span>
		<input name="username" type="text" id="username" value="<?php echo esc_attr( $username ); ?>"<?php disabled( defined( 'FTP_USER' ) ); ?> />
	</label>
</div>
<div class="ftp-password">
	<label for="password">
		<span class="field-title"><?php echo $label_pass; ?></span>
		<input name="password" type="password" id="password" value="<?php echo $password_value; ?>"<?php disabled( defined( 'FTP_PASS' ) ); ?> />
		<?php
		if ( ! defined( 'FTP_PASS' ) ) {
			_e( 'This password will not be stored on the server.' );}
		?>
	</label>
</div>
<fieldset>
<legend><?php _e( 'Connection Type' ); ?></legend>
	<?php
	$disabled = disabled( ( defined( 'FTP_SSL' ) && FTP_SSL ) || ( defined( 'FTP_SSH' ) && FTP_SSH ), true, false );
	foreach ( $types as $name => $text ) :
		?>
	<label for="<?php echo esc_attr( $name ); ?>">
		<input type="radio" name="connection_type" id="<?php echo esc_attr( $name ); ?>" value="<?php echo esc_attr( $name ); ?>" <?php checked( $name, $connection_type ); ?> <?php echo $disabled; ?> />
		<?php echo $text; ?>
	</label>
		<?php
	endforeach;
	?>
</fieldset>
	<?php
	if ( isset( $types['ssh'] ) ) {
		$hidden_class = '';
		if ( 'ssh' !== $connection_type || empty( $connection_type ) ) {
			$hidden_class = ' class="hidden"';
		}
		?>
<fieldset id="ssh-keys"<?php echo $hidden_class; ?>>
<legend><?php _e( 'Authentication Keys' ); ?></legend>
<label for="public_key">
	<span class="field-title"><?php _e( 'Public Key:' ); ?></span>
	<input name="public_key" type="text" id="public_key" aria-describedby="auth-keys-desc" value="<?php echo esc_attr( $public_key ); ?>"<?php disabled( defined( 'FTP_PUBKEY' ) ); ?> />
</label>
<label for="private_key">
	<span class="field-title"><?php _e( 'Private Key:' ); ?></span>
	<input name="private_key" type="text" id="private_key" value="<?php echo esc_attr( $private_key ); ?>"<?php disabled( defined( 'FTP_PRIKEY' ) ); ?> />
</label>
<p id="auth-keys-desc"><?php _e( 'Enter the location on the server where the public and private keys are located. If a passphrase is needed, enter that in the password field above.' ); ?></p>
</fieldset>
		<?php
	}

	foreach ( (array) $extra_fields as $field ) {
		if ( isset( $submitted_form[ $field ] ) ) {
			echo '<input type="hidden" name="' . esc_attr( $field ) . '" value="' . esc_attr( $submitted_form[ $field ] ) . '" />';
		}
	}

	// Make sure the `submit_button()` function is available during the REST API call
	// from WP_Site_Health_Auto_Updates::test_check_wp_filesystem_method().
	if ( ! function_exists( 'submit_button' ) ) {
		require_once ABSPATH . '/wp-admin/includes/template.php';
	}
	?>
	<p class="request-filesystem-credentials-action-buttons">
		<?php wp_nonce_field( 'filesystem-credentials', '_fs_nonce', false, true ); ?>
		<button class="button cancel-button" data-js-action="close" type="button"><?php _e( 'Cancel' ); ?></button>
		<?php submit_button( __( 'Proceed' ), '', 'upgrade', false ); ?>
	</p>
</div>
</form>
	<?php
	return false;
}