-
Notifications
You must be signed in to change notification settings - Fork 36
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Backported simple support for BIMI indicators
- Loading branch information
Showing
2 changed files
with
114 additions
and
7 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| /** | ||
| * Brand Indicators for Message Identification (BIMI). | ||
| * https://datatracker.ietf.org/doc/draft-brand-indicators-for-message-identification/04/ | ||
| * | ||
| * BIMI implementation for a Mail User Agent (MUA). | ||
| * Gets the BIMI Indicator based on the information the receiving | ||
| * Mail Transfer Agent (MTA) writes into the headers of the message. | ||
| * | ||
| * This is not a complete implementation of BIMI. | ||
| * | ||
| * Copyright (c) 2023 Philippe Lieser | ||
| * | ||
| * This software is licensed under the terms of the MIT License. | ||
| * | ||
| * The above copyright and license notice shall be | ||
| * included in all copies or substantial portions of the Software. | ||
| */ | ||
|
|
||
| // options for ESLint | ||
| /* global Components */ | ||
| /* global Logging */ | ||
| /* exported EXPORTED_SYMBOLS, BIMI */ | ||
|
|
||
| "use strict"; | ||
|
|
||
| var EXPORTED_SYMBOLS = [ | ||
| "BIMI" | ||
| ]; | ||
|
|
||
| // @ts-ignore | ||
| const Cu = Components.utils; | ||
|
|
||
| Cu.import("resource://dkim_verifier/logging.jsm.js"); | ||
| Cu.import("resource://dkim_verifier/ARHParser.jsm.js"); | ||
|
|
||
| let BIMI = (function() { | ||
|
|
||
| const log = Logging.getLogger("BIMI"); | ||
|
|
||
| // WSP as specified in Appendix B.1 of RFC 5234 | ||
| const WSP_p = "[ \t]"; | ||
| // obs-FWS as specified in Section 4.2 of RFC 5322 | ||
| const obs_FWS_p = `(?:${WSP_p}+(?:\r\n${WSP_p}+)*)`; | ||
| // FWS as specified in Section 3.2.2 of RFC 5322 | ||
| const FWS_p = `(?:(?:(?:${WSP_p}*\r\n)?${WSP_p}+)|${obs_FWS_p})`; | ||
|
|
||
| let that = { | ||
| /** | ||
| * Try to get the BIMI Indicator if available. | ||
| * | ||
| * @param {Map<string, string[]>} headers | ||
| * @param {ARHResinfo[]} arhBIMI - Trusted ARHs containing a BIMI result. | ||
| * @returns {string|null} | ||
| */ | ||
| getBimiIndicator: function(headers, arhBIMI) { | ||
| // Assuming: | ||
| // 1. We only get ARHs that can be trusted (i.e. from the receiving MTA). | ||
| // 2. If the receiving MTA does not supports BIMI, | ||
| // we will not see an ARH with a BIMI result (because of 1) | ||
| // 3. If the receiving MTA supports BIMI, | ||
| // it will make sure we only see his BIMI-Indicator headers (as required by the RFC). | ||
| // | ||
| // Given the above, it should be safe to trust the BIMI indicator from the BIMI-Indicator header | ||
| // if we have a passing BIMI result there the MTA claims to have checked the Authority Evidence. | ||
| const hasAuthorityPassBIMI = arhBIMI.some( | ||
| arh => arh.method === "bimi" && | ||
| arh.result === "pass" && | ||
| arh.propertys.policy.authority === "pass" | ||
| ); | ||
| if (!hasAuthorityPassBIMI) { | ||
| return null; | ||
| } | ||
|
|
||
| const bimiIndicators = headers.get("bimi-indicator") || []; | ||
| if (bimiIndicators.length > 1) { | ||
| log.warn("Message contains more than one BIMI-Indicator header"); | ||
| return null; | ||
| } | ||
| let bimiIndicator = bimiIndicators[0]; | ||
| if (!bimiIndicator) { | ||
| log.warn("Message contains an ARH with passing BIMI but does not have a BIMI-Indicator header"); | ||
| return null; | ||
| } | ||
|
|
||
| // TODO: If in the future we support ARC we might want to check the policy.indicator-hash | ||
|
|
||
| // Remove header name and new line at end | ||
| bimiIndicator = bimiIndicator.slice("bimi-indicator:".length, -"\r\n".length); | ||
| // Remove all whitespace | ||
| bimiIndicator = bimiIndicator.replace(new RegExp(`${FWS_p}`, "g"), ""); | ||
|
|
||
| return bimiIndicator; | ||
| } | ||
| }; | ||
| return that; | ||
| }()); |