aboutsummaryrefslogtreecommitdiff
path: root/background/webrequest.js
blob: f0c5b1be36a40e1cdbca76ad2fc4cb5b8d548274 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
/**
 * This file is part of Haketilo.
 *
 * Function: Modify HTTP traffic usng webRequest API.
 *
 * Copyright (C) 2021 Wojtek Kosior <koszko@koszko.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute forms of that code without the copy of the GNU
 * GPL normally required by section 4, provided you include this
 * license notice and, in case of non-source distribution, a URL
 * through which recipients can access the Corresponding Source.
 * If you modify file(s) with this exception, you may extend this
 * exception to your version of the file(s), but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * As a special exception to the GPL, any HTML file which merely
 * makes function calls to this code, and for that purpose
 * includes it by reference shall be deemed a separate work for
 * copyright law purposes. If you modify this code, you may extend
 * this exception to your version of the code, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
 * license. Although I request that you do not make use of this code in a
 * proprietary program, I am not going to enforce this in court.
 */

#IMPORT common/indexeddb.js        AS haketilodb
#IF MOZILLA
#IMPORT background/stream_filter.js
#ENDIF

#FROM common/browser.js IMPORT browser
#FROM common/misc.js    IMPORT is_privileged_url, csp_header_regex
#FROM common/policy.js  IMPORT decide_policy

#FROM background/patterns_query_manager.js IMPORT tree, default_allow

let secret;

function on_headers_received(details)
{
    const url = details.url;
    if (is_privileged_url(details.url))
	return;

    let headers = details.responseHeaders;

    const policy =
	  decide_policy(tree, details.url, !!default_allow.value, secret);
    if (policy.allow)
	return;

    if (policy.payload)
	headers = headers.filter(h => !csp_header_regex.test(h.name));

    headers.push({name: "Content-Security-Policy", value: policy.csp});

#IF MOZILLA
    let skip = false;
    for (const header of headers) {
	if (header.name.toLowerCase().trim() !== "content-disposition")
	    continue;

	if (/^\s*attachment\s*(;.*)$/i.test(header.value)) {
		skip = true;
	} else {
	    skip = false;
	    break;
	}
    }
    skip = skip || (details.statusCode >= 300 && details.statusCode < 400);

    if (!skip)
	headers = stream_filter.apply(details, headers, policy);
#ENDIF

    return {responseHeaders: headers};
}

#IF CHROMIUM && MV2
const request_url_regex = /^[^?]*\?url=(.*)$/;
const redirect_url_template = browser.runtime.getURL("dummy") + "?settings=";

function on_before_request(details)
{
    /*
     * Content script will make a synchronous XmlHttpRequest to extension's
     * `dummy` file to query settings for given URL. We smuggle that
     * information in query parameter of the URL we redirect to.
     * A risk of fingerprinting arises if a page with script execution allowed
     * guesses the dummy file URL and makes an AJAX call to it. It is currently
     * a problem in ManifestV2 Chromium-family port of Haketilo because Chromium
     * uses predictable URLs for web-accessible resources. We plan to fix it in
     * the future ManifestV3 port.
     */
    if (details.type !== "xmlhttprequest")
	return {cancel: true};

    if (details.url.startsWith(redirect_url_template))
	return;

#IF DEBUG
    console.debug(`Haketilo: Settings queried using XHR for '${details.url}'.`);
#ENDIF

    /*
     * request_url should be of the following format:
     *     <url_for_extension's_dummy_file>?url=<valid_urlencoded_url>
     */
    const match = request_url_regex.exec(details.url);
    if (match) {
	const queried_url = decodeURIComponent(match[1]);

	if (details.initiator && !queried_url.startsWith(details.initiator)) {
	    console.warn(`Haketilo: Blocked suspicious query of '${url}' by '${details.initiator}'. This might be the result of page fingerprinting the browser.`);
	    return {cancel: true};
	}

	const policy = decide_policy(tree, queried_url, default_allow, secret);
	if (!policy.error) {
	    const encoded_policy = encodeURIComponent(JSON.stringify(policy));
	    return {redirectUrl: redirect_url_template + encoded_policy};
	}
    }

    console.warn(`Haketilo: Bad request! Expected ${browser.runtime.getURL("dummy")}?url=<valid_urlencoded_url>. Got ${details.url}. This might be the result of page fingerprinting the browser.`);

    return {cancel: true};
}

const all_types = [
    "main_frame", "sub_frame", "stylesheet", "script", "image", "font",
    "object", "xmlhttprequest", "ping", "csp_report", "media", "websocket",
    "other", "main_frame", "sub_frame"
];
#ENDIF

async function start(secret_)
{
    secret = secret_;

#IF CHROMIUM
    const extra_opts = ["blocking", "extraHeaders"];
#ELSE
    const extra_opts = ["blocking"];
#ENDIF

    browser.webRequest.onHeadersReceived.addListener(
	on_headers_received,
	{urls: ["<all_urls>"], types: ["main_frame", "sub_frame"]},
	extra_opts.concat("responseHeaders")
    );

#IF CHROMIUM && MV2
    browser.webRequest.onBeforeRequest.addListener(
	on_before_request,
	{urls: [browser.runtime.getURL("dummy") + "*"], types: all_types},
	extra_opts
    );
#ENDIF
}
#EXPORT start