From bde8ac3e8e0c8f53630d47923d8e183123153458 Mon Sep 17 00:00:00 2001
From: kkapsner <github@mail.kkapsner.de>
Date: Tue, 28 Aug 2018 21:09:03 +0200
Subject: [PATCH] Only use onHeadersReceived listener when necessary

As mentioned in #214
---
 lib/dataUrls.js      | 61 +++++++++++++++++++++++++++++---------------
 test/dataUrlTest.php |  4 +--
 2 files changed, 42 insertions(+), 23 deletions(-)

diff --git a/lib/dataUrls.js b/lib/dataUrls.js
index 0f9b11c..55eb7d4 100644
--- a/lib/dataUrls.js
+++ b/lib/dataUrls.js
@@ -41,28 +41,47 @@
 	}
 	
 	scope.init = function(){
-		browser.webRequest.onHeadersReceived.addListener(
-			function(details){
+		function listener(details){console.log("listener");
+			const headers = details.responseHeaders;
+			if (settings.blockDataURLs){
 				const cspMatch = (blockBlob? "": "blob: ") + "filesystem: *";
-				const headers = details.responseHeaders;
-				if (settings.blockDataURLs){
-					logging.verbose("Adding CSP header to", details);
-					setHeader(headers, {
-						name: "Content-Security-Policy",
-						value: `object-src ${cspMatch}; frame-src ${cspMatch}`
-						//	+ "; report-to https://canvasblocker.invalid/; report-uri https://canvasblocker.invalid/"
-					});
-				}
-				return {
-					responseHeaders: headers
-				};
-			},
-			{
-				urls: ["<all_urls>"],
-				types: ["main_frame", "sub_frame", "object"]
-			},
-			["blocking", "responseHeaders"]
-		);
+				logging.verbose("Adding CSP header to", details);
+				setHeader(headers, {
+					name: "Content-Security-Policy",
+					value: `object-src ${cspMatch}; frame-src ${cspMatch}`
+					//	+ "; report-to https://canvasblocker.invalid/; report-uri https://canvasblocker.invalid/"
+				});
+			}
+			return {
+				responseHeaders: headers
+			};
+		}
+		function addListener(){
+			if (!browser.webRequest.onHeadersReceived.hasListener(listener)){
+				browser.webRequest.onHeadersReceived.addListener(
+					listener,
+					{
+						urls: ["<all_urls>"],
+						types: ["main_frame", "sub_frame", "object"]
+					},
+					["blocking", "responseHeaders"]
+				);
+			}
+		}
+		function removeListener(){
+			browser.webRequest.onHeadersReceived.removeListener(listener);
+		}
+		function adjustListener(){
+			if (settings.blockDataURLs){
+				addListener();
+			}
+			else {
+				removeListener();
+			}
+		}
+		
+		settings.onloaded(adjustListener);
+		settings.on("blockDataURLs", adjustListener);
 	};
 
 }());
\ No newline at end of file
diff --git a/test/dataUrlTest.php b/test/dataUrlTest.php
index e83ae2a..2771b36 100644
--- a/test/dataUrlTest.php
+++ b/test/dataUrlTest.php
@@ -29,7 +29,7 @@
 	<iframe id="blobIframe"></iframe>
 	<h1>Data-URL object</h1>
 	<object
-		type="invalid"
+		type="text/html"
 		data="data:invalid;base64&#x2c;<?php
 			echo base64_encode(
 				str_replace(
@@ -42,7 +42,7 @@
 	></object>
 	<h1>Data-URL embed</h1>
 	<embed
-		type="invalid"
+		type="text/html"
 		src="data:invalid;base64&#x2c;<?php
 			echo base64_encode(
 				str_replace(