AsyncHttp\\Client: Use false, not null to indicate missing response headers

For transfer-encoding: chunked, the content-length header was missing.
A confusion around checking for false vs null made the client assume no
response body is coming back and close the connection prematurely.

Author: adamziel

http_proxy.php

@@ -57,7 +57,7 @@ function get_target_url($server_data=null) {
 	switch ( $client->get_event() ) {
 		case Client::EVENT_GOT_HEADERS:
 			http_response_code($request->response->status_code);
-			foreach ( $request->response->get_headers() as $name => $value ) {
+			foreach ( $request->response->headers as $name => $value ) {
 				if(
 					$name === 'transfer-encoding' ||
 					$name === 'set-cookie' ||

src/WordPress/AsyncHttp/Client.php

@@ -590,7 +590,7 @@ private function receive_response_headers( $requests ) {
 				$response->protocol       = $parsed['status']['protocol'];
 
 				$total = $request->response->get_header( 'content-length' );
-				if ( $total !== null ) {
+				if ( false !== $total ) {
 					$response->total_bytes = (int) $total;
 				}
 
@@ -660,7 +660,7 @@ private function handle_redirects( $requests ) {
 			}
 
 			$location = $response->get_header( 'location' );
-			if ( $location === null ) {
+			if ( false === $location ) {
 				continue;
 			}
 

src/WordPress/AsyncHttp/Response.php

@@ -18,19 +18,7 @@ public function __construct( Request $request ) {
 	}
 
 	public function get_header( $name ) {
-		$headers = $this->get_headers();
-		if ( false === $headers ) {
-			return false;
-		}
-		return $headers[ strtolower( $name ) ] ?? false;
-	}
-
-	public function get_headers() {
-		if ( ! $this->headers ) {
-			return false;
-		}
-
-		return $this->headers;
+		return $this->headers[ strtolower( $name ) ] ?? false;
 	}
 
 }