1 files changed, 59 insertions, 4 deletions

diff --git a/data/extensions/jsr@javascriptrestrictor/background.js b/data/extensions/jsr@javascriptrestrictor/background.js
index ab7cac9..019b76c 100644
--- a/data/extensions/jsr@javascriptrestrictor/background.js
+++ b/data/extensions/jsr@javascriptrestrictor/background.js
@@ -3,6 +3,7 @@
  *
  *  \author Copyright (C) 2019  Libor Polcak
  *  \author Copyright (C) 2019  Martin Timko
+ *  \author Copyright (C) 2023  Martin Zmitko
  *
  *  \license SPDX-License-Identifier: GPL-3.0-or-later
  */
@@ -43,13 +44,62 @@ function tabUpdate(tabid, changeInfo) {
 	if (url === undefined) {
 		return wrapping_groups.empty_level;
 	}
-	let current_level = getCurrentLevelJSON(url)[0];
+	let current_level = getCurrentLevelJSON(url);
 	tab_urls[tabid] = url;
 	return current_level;
 }
 // on tab reload or tab change, update metadata
 browser.tabs.onUpdated.addListener(tabUpdate);     // reload tab
 
+const scriptSrcRegex = /script-src\s/;
+// Modify CSP headers to allow WASM execution in page context
+function cspRequestProcessor(details) {
+	// Because this handler fires before configuration for the page is created,
+	// we need to search for the configuration for that domain now.
+	let subDomains = extractSubDomains(getEffectiveDomain(details.url));
+	let found = false;
+	for (let domain of subDomains.reverse()) {
+		if (domain in domains) {
+			found = true;
+			if (domains[domain].wasm !== 2) {
+				return {};
+			}
+			break;
+		}
+	}
+	// If no configuration is found, use the default level.
+	if (!found && default_level.wasm !== 2) {
+		return {};
+	}
+
+	let modified = false;
+	let headers = details.responseHeaders;
+	for (let header of headers) {
+		let name = header.name.toLowerCase();
+		if (name !== "content-security-policy" &&
+			name !== "content-security-policy-report-only" &&
+			name !== "x-webkit-csp") {
+			continue;
+		}
+		let origCSP = header.value;
+		header.value = header.value.replace(scriptSrcRegex, "script-src 'wasm-unsafe-eval' ");
+		if (origCSP !== header.value) {
+			modified = true;
+		}
+	}
+	return modified ? {responseHeaders: headers} : {};
+}
+// Attach listener only in chromium where the WASM module is instantiated directly in
+// page context, subject to the page's CSP. Code inserted as script tags isn't subject
+// to script-src origins, it is, however, subject to the 'unsafe' group of script evaluation rules.
+if (typeof browser_polyfill_used !== "undefined" && browser_polyfill_used) {
+	browser.webRequest.onHeadersReceived.addListener(cspRequestProcessor,
+		{urls: ["<all_urls>"],
+		types: ["main_frame", "sub_frame"]},
+		["blocking", "responseHeaders"]
+	);
+}
+
 // Communication channels
 
 /**
@@ -61,9 +111,14 @@ browser.tabs.onUpdated.addListener(tabUpdate);     // reload tab
  */
 async function connected(port) {
 	if (port.name === "port_from_popup") {
-		/// We always send back current level
-		let [tab] = await browser.tabs.query(queryInfo);
-		let current_level = tabUpdate(tab.id, tab.url);
+		let current_level = wrapping_groups.empty_level;
+		try {
+			// We always send back current level
+			let [tab] = await browser.tabs.query(queryInfo);
+			current_level = getCurrentLevelJSON(tab.url);
+		} catch (e) {
+			// Stick to the empty_level and ignore the exception
+		}
 		port.postMessage(current_level);
 		port.onMessage.addListener(function(msg) {
 			port.postMessage(current_level);