discover_pingback_server_uri( string $url, string $deprecated = '' ): string|false

Description

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$urlstring

URL to ping.

$deprecatedstringoptional

Not Used.Default: ''

Return value

string|false

String containing URI on success, false on failure.

Performance profile

How much work a call to discover_pingback_server_uri() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Expensive

Reaches an outbound HTTP request via wp_safe_remote_head().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

11–77

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 90.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

1

1 place in core call this, so the cost is paid more often than your own code shows.

What it touches

• httpoutbound HTTP requestwp_safe_remote_head()called directly
• hookthird-party callbacksdo_action()one call below discover_pingback_server_uri()

Further down the call graph this can also reach option, cache, serialize, query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 12 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost discover_pingback_server_uri() can have, taken from its control-flow graph on PHP 8.5.

Uses · 8

• _deprecated_argument()Marks a function argument as deprecated and inform when it has been used.
• wp_get_upload_dir()Retrieves uploads directory information.
• str_starts_with()Polyfill for `str_starts_with()` function added in PHP 8.0.
• wp_safe_remote_head()Retrieves the raw response from a safe HTTP request using the HEAD method.
• is_wp_error()Checks whether the given variable is a WordPress Error.
• wp_remote_retrieve_header()Retrieves a single header by name from the raw response.
• wp_safe_remote_get()Retrieves the raw response from a safe HTTP request using the GET method.
• wp_remote_retrieve_body()Retrieves only the body from the raw response.

Used by · 1

• pingback()Pings back the links found in a post.

Source code

View on Trac ↗View on GitHub ↗

2924function discover_pingback_server_uri( $url, $deprecated = '' ) {2925	if ( ! empty( $deprecated ) ) {2926		_deprecated_argument( __FUNCTION__, '2.7.0' );2927	}2928 2929	$pingback_str_dquote = 'rel="pingback"';2930	$pingback_str_squote = 'rel=\'pingback\'';2931 2932	/** @todo Should use Filter Extension or custom preg_match instead. */2933	$parsed_url = parse_url( $url );2934 2935	if ( ! isset( $parsed_url['host'] ) ) { // Not a URL. This should never happen.2936		return false;2937	}2938 2939	// Do not search for a pingback server on our own uploads.2940	$uploads_dir = wp_get_upload_dir();2941	if ( str_starts_with( $url, $uploads_dir['baseurl'] ) ) {2942		return false;2943	}2944 2945	$response = wp_safe_remote_head(2946		$url,2947		array(2948			'timeout'     => 2,2949			'httpversion' => '1.0',2950		)2951	);2952 2953	if ( is_wp_error( $response ) ) {2954		return false;2955	}2956 2957	if ( wp_remote_retrieve_header( $response, 'X-Pingback' ) ) {2958		return wp_remote_retrieve_header( $response, 'X-Pingback' );2959	}2960 2961	// Not an (x)html, sgml, or xml page, no use going further.2962	if ( preg_match( '#(image|audio|video|model)/#is', wp_remote_retrieve_header( $response, 'Content-Type' ) ) ) {2963		return false;2964	}2965 2966	// Now do a GET since we're going to look in the HTML headers (and we're sure it's not a binary file).2967	$response = wp_safe_remote_get(2968		$url,2969		array(2970			'timeout'     => 2,2971			'httpversion' => '1.0',2972		)2973	);2974 2975	if ( is_wp_error( $response ) ) {2976		return false;2977	}2978 2979	$contents = wp_remote_retrieve_body( $response );2980 2981	$pingback_link_offset_dquote = strpos( $contents, $pingback_str_dquote );2982	$pingback_link_offset_squote = strpos( $contents, $pingback_str_squote );2983 2984	if ( $pingback_link_offset_dquote || $pingback_link_offset_squote ) {2985		$quote                   = ( $pingback_link_offset_dquote ) ? '"' : '\'';2986		$pingback_link_offset    = ( '"' === $quote ) ? $pingback_link_offset_dquote : $pingback_link_offset_squote;2987		$pingback_href_pos       = strpos( $contents, 'href=', $pingback_link_offset );2988		$pingback_href_start     = $pingback_href_pos + 6;2989		$pingback_href_end       = strpos( $contents, $quote, $pingback_href_start );2990		$pingback_server_url_len = $pingback_href_end - $pingback_href_start;2991		$pingback_server_url     = substr( $contents, $pingback_href_start, $pingback_server_url_len );2992 2993		// We may find rel="pingback" but an incomplete pingback URL.2994		if ( $pingback_server_url_len > 0 ) { // We got it!2995			return $pingback_server_url;2996		}2997	}2998 2999	return false;3000}

Changelog

Introduced in 1.5.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.0.4 tag, from src/wp-includes/comment.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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