BUG Setting response length directly before output (fixes #7574)

Complying to HTTP1.1/RFC2616 in terms of when to
set 'Content-Length' in the first place

control/Director.php

@@ -141,6 +141,17 @@ public static function direct($url, DataModel $model) {
 						number_format(memory_get_peak_usage(),0)
 					));
 				} else {
+					// Set content length (according to RFC2616)
+					if(
+						!headers_sent()
+						&& $response->getBody() 
+						&& $req->httpMethod() != 'HEAD' 
+						&& $response->getStatusCode() >= 200
+						&& !in_array($response->getStatusCode(), array(204, 304))
+					) {
+						$response->fixContentLength();
+					}
+
 					$response->output();
 				}
 			} else {

control/HTTPResponse.php

@@ -150,9 +150,6 @@ public function isError() {
 
 	public function setBody($body) {
 		$this->body = $body;
-
-		// Set content-length in bytes. Use mbstring to avoid problems with mb_internal_encoding() and mbstring.func_overload
-		$this->headers['Content-Length'] = mb_strlen($this->body,'8bit');
 	}
 
 	public function getBody() {
@@ -248,6 +245,14 @@ public function output() {
 	public function isFinished() {
 		return in_array($this->statusCode, array(301, 302, 401, 403));
 	}
+
+	/**
+	 * Set content-length in bytes. Should be called right before {@link output()}.
+	 */
+	public function fixContentLength() {
+		// Use mbstring to avoid problems with mb_internal_encoding() and mbstring.func_overload
+		$this->headers['Content-Length'] = mb_strlen($this->body,'8bit');	
+	}
 
 }
 

tests/control/HTTPResponseTest.php

@@ -15,6 +15,7 @@ public function testStatusDescriptionStripsNewlines() {
 
 	public function testContentLengthHeader() {
 		$r = new SS_HTTPResponse('123ü');
+		$r->fixContentLength();
 		$this->assertNotNull($r->getHeader('Content-Length'), 'Content-length header is added');
 		$this->assertEquals(
 			5, 
@@ -23,6 +24,7 @@ public function testContentLengthHeader() {
 		);
 
 		$r->setBody('1234ü');
+		$r->fixContentLength();
 		$this->assertEquals(
 			6, 
 			$r->getHeader('Content-Length'),