Socket-based HTTP transport using stream_socket_client(). Serves as the fallback when cURL is unavailable.

Source: wp-includes/Requests/src/Transport/Fsockopen.php
Namespace: WpOrgRequestsTransport
Implements: WpOrgRequestsTransport
Declared: final class Fsockopen

Constants

Properties

Public

Private

Methods

request()

public function request(
    string|Stringable $url,
    array $headers = [],
    string|array $data = [],
    array $options = []
): string

Perform an HTTP request via stream_socket_client().

Flow:

1. Validates arguments
2. Dispatches fsockopen.before_request
3. Parses URL, creates stream context
4. HTTPS: Configures SSL context options:
   • verify_peer → true (default)
   • capture_peer_cert → true
   • SNI enabled if OPENSSL_TLSEXT_SERVER_NAME defined
   • Custom CA file from $options['verify']
   • Peer name verification from $options['verifyname']
5. Dispatches fsockopen.remote_socket hook with &$remote_socket
6. Connects via stream_socket_client() with connection timeout
7. For HTTPS, verifies certificate against hostname via verify_certificate_from_context()
8. Formats request line and data based on data_format
9. Dispatches fsockopen.remote_host_path hook
10. Builds raw HTTP request: method line, Host, User-Agent, Accept-Encoding, custom headers
11. Dispatches fsockopen.after_headers, fsockopen.before_send
12. Writes to socket via fwrite()
13. Dispatches fsockopen.after_send
14. For non-blocking: closes socket, returns empty string
15. Sets stream timeout (supports fractional seconds via microseconds)
16. Reads response in BUFFER_SIZE chunks, splitting headers from body
17. Enforces max_bytes limit on body
18. Supports streaming to file via $options['filename']
19. Dispatches fsockopen.after_request with &$headers, &$info

Throws:

• verify_peer → true (default)
• capture_peer_cert → true
• SNI enabled if OPENSSL_TLSEXT_SERVER_NAME defined
• Custom CA file from $options['verify']
• Peer name verification from $options['verifyname']

Auto-added headers (if not already set):

• verify_peer → true (default)
• capture_peer_cert → true
• SNI enabled if OPENSSL_TLSEXT_SERVER_NAME defined
• Custom CA file from $options['verify']
• Peer name verification from $options['verifyname']

request_multiple()

public function request_multiple( array $requests, array $options ): array

Send multiple requests sequentially (no parallel support). Creates a new Fsockopen instance per request, dispatches transport.internal.parse_response and multiple.request.complete hooks.

On exception, stores the Exception object as the response for that request ID.

Throws: InvalidArgument for invalid parameter types.

test() (static)

public static function test( array $capabilities = [] ): bool

Checks:

1. fsockopen() function exists
2. If Capability::SSL requested, checks openssl extension and openssl_x509_parse() function

verify_certificate_from_context()

public function verify_certificate_from_context( string $host, resource $context ): bool

Verify the SSL certificate against hostname using the stream context’s peer certificate. PHP doesn’t check Subject Alternative Names by default; this method uses Ssl::verify_certificate() to handle that.

Throws:

• InvalidArgument for invalid parameter types
• Exception — Invalid URL (invalidurl)
• Exception — Connection failure (fsockopen.connect_error or fsockopenerror)
• Exception — Socket timeout (timeout)
• Exception — SSL mismatch (ssl.no_match)
• Exception — File open failure (fopen)

connect_error_handler()

public function connect_error_handler( int $errno, string $errstr ): bool

Custom error handler for stream_socket_client(). Captures E_WARNING and E_NOTICE messages into $this->connect_error. Returns false for other error types.

Private Methods

Differences from cURL Transport