background.js

var isTampering = false;
var types = [];
var pattern = false;
var tabId = browser.tabs.TAB_ID_NONE;

var msgHandler = ()=>{};
function handleMessage(msg){
	msgHandler(msg);
}

function tamper_header_listener(e) {
	if((e.originUrl || "").indexOf("moz-extension://") === 0) return e;
	if(!~types.indexOf(e.type)) return e;
	if(pattern && null === e.url.match(RegExp(pattern, "g"))) return e;
	return new Promise(done=>{
		var data = {
			requestId: e.requestId,
			method: e.method,
			url: e.url,
			type: e.type,
			headers: [],
		};
		e.requestHeaders.forEach(function (header) {
			data.headers.push({
				name: header.name,
				value: header.value
			});
		});
		user_modify_headers(data).then(res=>{
			if(res.race) {
				return done({cancel: true});
			}
			if(res.stop) stop_tampering();
			done({requestHeaders: res.headers});
		});
	});
}

function tamper_request_listener(e){
	if((e.originUrl || "").indexOf("moz-extension://") === 0) return e;
	if(!~types.indexOf(e.type)) return e;
	if(pattern && null === e.url.match(RegExp(pattern, "g"))) return e;
	return new Promise(done=>{
		var formData = "";
		if(e.requestBody && e.requestBody.formData){
			for(var n in e.requestBody.formData){
				if(e.requestBody.formData.hasOwnProperty(n)) {
				 	formData = formData + "&" + n + "=" + e.requestBody.formData[n][0];
				 }
			}
			if(formData.length>1) {
				formData = formData.substring(1); // remove first  &
			}
		}
		//var bodyRaw = (e.requestBody && e.requestBody.raw) ? String.fromCharCode.apply(null,new Uint8Array(e.requestBody.raw[0].bytes)) : "";
		var bodyRaw = (e.requestBody && e.requestBody.raw) ? e.requestBody.raw.map(function(data) { return String.fromCharCode.apply(null, new Uint8Array(data.bytes)) }).join('') : "";
		var data = {
			requestId: e.requestId,
			method: e.method,
			url: e.url,
			type: e.type,
			requestBody: e.requestBody,
			body: decodeURIComponent(formData) + decodeURIComponent(bodyRaw)
		};
		console.log("requestBody in raw", data);
		user_modify_body(data).then(res=>{
			if(res.stop) stop_tampering();
			if(res.cancel) return done({cancel: true});
			if(res.redirect) return done({redirectUrl: res.redirect});
			done(e);
		});
	});
}

function stop_tamper_listener(){
	var listening = browser.webRequest.onBeforeSendHeaders.hasListener(tamper_header_listener);
	if(listening){
		browser.webRequest.onBeforeSendHeaders.removeListener(tamper_header_listener);
		browser.webRequest.onBeforeRequest.removeListener(tamper_request_listener);
	}
}

function start_tamper_listener(){
	const filters = {urls: ["<all_urls>"]};
	if (tabId !== browser.tabs.TAB_ID_NONE)
		filters.tabId = tabId;

	browser.webRequest.onBeforeSendHeaders.addListener(
		tamper_header_listener,
		filters,
		["blocking", "requestHeaders"]
	);
	browser.webRequest.onBeforeRequest.addListener(
		tamper_request_listener,
		filters,
		["blocking", "requestBody"]
	);
}

function user_confirm_tamper(tab_id){
	return new Promise(done=>{
		browser.windows.create({
			url: "popups/confirm_tamper/popup.html?"+encodeURIComponent(JSON.stringify({
				types: types,
				pattern: pattern,
				tab: tabId !== browser.tabs.TAB_ID_NONE,
			})),
			type: "panel",
			width: 950,
			height: 900,
			allowScriptsToClose: true
		}).then(w=>{
			msgHandler = msg=>{
				types = msg.types;
				pattern = msg.pattern;
				tabId = msg.tab ? tab_id : browser.tabs.TAB_ID_NONE;
				browser.windows.getCurrent().then(wi=>{
					browser.windows.remove(wi.id);
					done(msg);
				});
			};
		});
	});
}

function user_modify_headers(data){
	return new Promise(done=>{
		browser.windows.create({
			url: "popups/tamper_headers/popup.html?"+encodeURIComponent(JSON.stringify(data)),
			type: "panel",
			width: 500,
			height: 700,
			allowScriptsToClose: true
		}).then(w=>{
			msgHandler = msg=>{
				browser.windows.getCurrent().then(wi=>{
					browser.windows.remove(wi.id);
					done(msg);
				});
			};
		});
	});
}

function user_modify_body(data){
	return new Promise(done=>{
		browser.windows.create({
			url: "popups/tamper_body/popup.html?"+encodeURIComponent(JSON.stringify(data)),
			type: "panel",
			width: 600,
			height: 600,
			allowScriptsToClose: true
		}).then(w=>{
			msgHandler = msg=>{
				browser.windows.getCurrent().then(wi=>{
					browser.windows.remove(wi.id);
					done(msg);
				});
			};
		});
	});
}

function confirm_and_start_tamper(tab_id){
	user_confirm_tamper(tab_id).then(res=>{
		if(res.tamper === true){
			isTampering = true;
			browser.browserAction.setIcon({
				path: {
					"48": "icons/icon-tamper-48.png",
					"32": "icons/icon-tamper-32.png",
					"16": "icons/icon-tamper-16.png"
				}
			});
			browser.browserAction.setTitle({title: "RC Interceptor: Enabled"});
			start_tamper_listener();
		}
	});
}

function stop_tampering(){
	isTampering = false;
	browser.browserAction.setIcon({
		path: {
			"48": "icons/icon-notamper-48.png",
			"32": "icons/icon-notamper-32.png",
			"16": "icons/icon-notamper-16.png"
		}
	});
	browser.browserAction.setTitle({title: "RC Interceptor: Disabled"});
	stop_tamper_listener();
}


browser.runtime.onMessage.addListener(handleMessage);
browser.browserAction.onClicked.addListener((tab)=>{
	if(!isTampering) confirm_and_start_tamper(tab.id);
	else stop_tampering();
});