feat: add firefox-stable-unsigned-addons

content/posts/firefox-stable-unsigned-addons.md

@@ -0,0 +1,97 @@
+---
+title: "Installing unsigned addons in Firefox stable"
+date: 2022-08-27T01:14:28+02:00
+draft: false
+---
+
+When developing a private addon, you don't always want to use Mozilla services - it's your browser, why should they care about your addons?
+Unfortunately, when looking at the [documentation][1] and forum posts, it doesn't seem like you can install them on the stable version of Firefox...
+or can you?
+
+![Pop-up in Firefox - This addon could not be installed because it has not been verified](/posts/firefox-stable-unsigned-addons/not-verified.png)
+
+(before you proceed, make sure your addon has the [browser_specific_settings][2] section; otherwise, it's gonna show as corrupted to Firefox)
+
+To achieve this, we're gonna need a text editor and write access to your browser files (usually root/Administrator).
+These instructions are gonna target Linux with Firefox installed from your system package manager (so excluding Flatpak or Snap),
+but it should be possible to do this anywhere, as long as you can edit these files.
+
+Firstly, locate the `omni.ja` file in the browser files (usually `/usr/lib/firefox`).
+There's two of them, one in the `browser/` subdirectory - we're gonna focus on the other one.
+
+There are three things we need to patch:
+- [`modules/AppConstants.jsm:203`][3]
+```diff
+--- a/modules/AppConstants.jsm
++++ b/modules/AppConstants.jsm
+@@ -203,3 +203,3 @@
+   MOZ_REQUIRE_SIGNING:
+ //@line 290 "$SRCDIR/toolkit/modules/AppConstants.jsm"
+-  true,
++  0000,
+```
+- [`modules/addons/XPIDatabase.jsm:2366`][4]
+```diff
+--- a/modules/addons/XPIDatabase.jsm
++++ b/modules/addons/XPIDatabase.jsm
+@@ -2366,7 +2366,7 @@
+     if (this.mustSign(aAddon.type) && !aAddon.isCorrectlySigned) {
+       logger.warn(`Add-on ${aAddon.id} is not correctly signed.`);
+       if (Services.prefs.getBoolPref(PREF_XPI_SIGNATURES_DEV_ROOT, false)) {
+         logger.warn(`Preference ${PREF_XPI_SIGNATURES_DEV_ROOT} is set.`);
+       }
+-      return false;
++    //return false;
+     }
+```
+- [`modules/addons/XPIInstall.jsm:1609`][5]
+```diff
+--- a/modules/addons/XPIInstall.jsm
++++ b/modules/addons/XPIInstall.jsm
+@@ -1609,4 +1609,4 @@
+-      if (lazy.XPIDatabase.mustSign(this.addon.type)) {
++      if (false /*Database.mustSign(this.addon.typ*/) {
+         if (this.addon.signedState <= AddonManager.SIGNEDSTATE_MISSING) {
+           // This add-on isn't properly signed by a signature that chains to the
+           // trusted root.
+```
+
+As the `omni.ja` file is just a zip file, you can unpack it:
+```bash-session
+$ mkdir omni && cd omni
+$ unzip ../omni.ja
+Archive:  ../omni.ja
+warning [../omni.ja]:  29257828 extra bytes at beginning or within zipfile
+  (attempting to process anyway)
+error [../omni.ja]:  reported length of central directory is
+  -29257828 bytes too long (Atari STZip zipfile?  J.H.Holm ZIPSPLIT 1.1
+  zipfile?).  Compensating...
+ extracting: greprefs.js
+ extracting: chrome.manifest
+ extracting: chrome/chrome.manifest
+...
+```
+
+It seems to complain about some stuff, but that doesn't seem to be too much of an issue.  
+After editing, just repack:
+
+```console
+$ zip -r -0 -FS omni.ja *
+  adding: actors/ (stored 0%)
+  adding: actors/WebChannelParent.jsm (stored 0%)
+  adding: actors/WebChannelChild.jsm (stored 0%)
+  adding: actors/ViewSourcePageParent.jsm (stored 0%)
+...
+```
+and replace the original file with the modified one.
+
+With all that done, restart Firefox, go to `about:addons` and load your addon.
+Depite the big red warning, the extension should now be loaded and usable.
+
+![Snippet of Firefox addons page, with addon named demo addon and warning that it has not been verified for use in Firefox](/posts/firefox-stable-unsigned-addons/demo-addon.png)
+
+[1]: https://wiki.mozilla.org/Add-ons/Extension_Signing
+[2]: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_specific_settings
+[3]: https://searchfox.org/mozilla-central/source/toolkit/modules/AppConstants.jsm#285
+[4]: https://searchfox.org/mozilla-central/source/toolkit/mozapps/extensions/internal/XPIDatabase.jsm#2391
+[5]: https://searchfox.org/mozilla-central/source/toolkit/mozapps/extensions/internal/XPIInstall.jsm#1608