Ensure post abstraction methods use correct site ID.

includes/classes/DistributorPost.php

@@ -94,6 +94,13 @@ class DistributorPost {
 	 */
 	public $connection_id = 0;
 
+	/**
+	 * The site ID of this post.
+	 *
+	 * @var int
+	 */
+	public $site_id = 0;
+
 	/**
 	 * The source site data for internal connections.
 	 *
@@ -122,7 +129,8 @@ public function __construct( $post ) {
 			return;
 		}
 
-		$this->post = $post;
+		$this->post    = $post;
+		$this->site_id = get_current_blog_id();
 
 		/*
 		 * The original post ID is listed as excluded post meta and therefore
@@ -178,6 +186,74 @@ public function __construct( $post ) {
 		}
 	}
 
+	/**
+	 * Magic method for calling methods on the post object.
+	 *
+	 * This is used to ensure the post object is switched to the correct site before
+	 * running any of the internal methods.
+	 *
+	 * @param string $name      Method name.
+	 * @param array  $arguments Method arguments.
+	 */
+	public function __call( $name, $arguments ) {
+		$switched = false;
+		if ( ! method_exists( $this, $name ) ) {
+			// Emulate default behavior of calling non existent method (a fatal error).
+			// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error, WordPress.Security.EscapeOutput -- class and name are safe.
+			trigger_error( 'Call to undefined method ' . __CLASS__ . '::' . $name . '()', E_USER_ERROR );
+		}
+
+		if ( get_current_blog_id() !== $this->site_id ) {
+			if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
+				// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error -- throwing a warning is the correct behavior.
+				trigger_error( 'DistributorPost object is not on the correct site.', E_USER_WARNING );
+			}
+			switch_to_blog( $this->site_id );
+			$switched = true;
+		}
+		$result = call_user_func_array( array( $this, $name ), $arguments );
+		if ( $switched ) {
+			restore_current_blog();
+		}
+		return $result;
+	}
+
+	/**
+	 * Magic getter method.
+	 *
+	 * This method is used to get the value of the `source_site` property and
+	 * populate it if needs be. For internal connections the post permalink is
+	 * updated with live data.
+	 *
+	 * @param string $name Property name.
+	 * @return mixed
+	 */
+	public function __get( $name ) {
+		if ( in_array( $name, array( 'source_site', 'original_post_url' ), true ) ) {
+			$this->populate_source_site();
+		}
+
+		return $this->$name;
+	}
+
+	/**
+	 * Magic isset method.
+	 *
+	 * This method is used to check if the `source_site` property is set and
+	 * populate it if needs be.
+	 *
+	 * @param string $name Property name.
+	 * @return bool
+	 */
+	public function __isset( $name ) {
+		if ( 'source_site' === $name && empty( $this->source_site ) ) {
+			$this->populate_source_site();
+			return ! empty( $this->source_site );
+		}
+
+		return isset( $this->$name );
+	}
+
 	/**
 	 * Populate the source site data for internal connections.
 	 *
@@ -232,42 +308,6 @@ protected function populate_source_site() {
 		}
 	}
 
-	/**
-	 * Magic getter method.
-	 *
-	 * This method is used to get the value of the `source_site` property and
-	 * populate it if needs be. For internal connections the post permalink is
-	 * updated with live data.
-	 *
-	 * @param string $name Property name.
-	 * @return mixed
-	 */
-	public function __get( $name ) {
-		if ( in_array( $name, array( 'source_site', 'original_post_url' ), true ) ) {
-			$this->populate_source_site();
-		}
-
-		return $this->$name;
-	}
-
-	/**
-	 * Magic isset method.
-	 *
-	 * This method is used to check if the `source_site` property is set and
-	 * populate it if needs be.
-	 *
-	 * @param string $name Property name.
-	 * @return bool
-	 */
-	public function __isset( $name ) {
-		if ( 'source_site' === $name && empty( $this->source_site ) ) {
-			$this->populate_source_site();
-			return ! empty( $this->source_site );
-		}
-
-		return isset( $this->$name );
-	}
-
 	/**
 	 * Determines whether the post has blocks.
 	 *

tests/php/DistributorPostTest.php

@@ -34,6 +34,13 @@ public function setup_common() {
 			]
 		);
 
+		\WP_Mock::userFunction(
+			'get_current_blog_id',
+			[
+				'return' => 1,
+			]
+		);
+
 		// Return voids.
 		\WP_Mock::userFunction( '_prime_post_caches' );
 		\WP_Mock::userFunction( 'update_object_term_cache' );

tests/php/HooksTest.php

@@ -17,6 +17,12 @@ class HooksTest extends TestCase {
 	public function setUp(): void {
 		parent::setUp();
 
+		\WP_Mock::userFunction(
+			'get_current_blog_id',
+			[
+				'return' => 1,
+			]
+		);
 
 		// Return voids.
 		\WP_Mock::userFunction( '_prime_post_caches' );