[bug#44335] [PATCH 2/2] gnu: Add ublock-origin-chromium.

[Marius Bakke]

* gnu/packages/browser-extensions.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Adjust accordingly.
---
 gnu/local.mk                        |   1 +
 gnu/packages/browser-extensions.scm | 278 ++++++++++++++++++++++++++++
 2 files changed, 279 insertions(+)
 create mode 100644 gnu/packages/browser-extensions.scm

diff --git a/gnu/local.mk b/gnu/local.mk
index 4643d05049..f97a0cda78 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -111,6 +111,7 @@ GNU_SYSTEM_MODULES =                                \
   %D%/packages/boost.scm                       \
   %D%/packages/bootloaders.scm                 \
   %D%/packages/bootstrap.scm                   \
+  %D%/packages/browser-extensions.scm          \
   %D%/packages/build-tools.scm                 \
   %D%/packages/busybox.scm                     \
   %D%/packages/c.scm                           \
diff --git a/gnu/packages/browser-extensions.scm 
b/gnu/packages/browser-extensions.scm
new file mode 100644
index 0000000000..b6d160bee7
--- /dev/null
+++ b/gnu/packages/browser-extensions.scm
@@ -0,0 +1,278 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2020 Marius Bakke <marius@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix 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.
+;;;
+;;; GNU Guix 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.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu packages browser-extensions)
+  #:use-module (gcrypt base16)
+  #:use-module ((gcrypt hash) #:prefix hash:)
+  #:use-module (ice-9 iconv)
+  #:use-module (guix gexp)
+  #:use-module (guix packages)
+  #:use-module (gnu packages base)
+  #:use-module (gnu packages check)
+  #:use-module (gnu packages chromium)
+  #:use-module (gnu packages gnupg)
+  #:use-module (gnu packages tls)
+  #:use-module (gnu packages xorg)
+  #:use-module (guix build-system trivial)
+
+  ;; Imports for extension packages.
+  #:use-module (guix git-download)
+  #:use-module (guix build-system gnu)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (gnu packages compression)
+  #:use-module (gnu packages python)
+
+  #:export (make-chromium-extension))
+
+;; Chromium requires that each package is signed with a unique key, from which
+;; the "extension ID" derives.  Currently the package name is used as seed.
+(define (make-signing-key seed)
+  "Return a derivation for a deterministic PKCS #8 private key using SEED."
+
+  (define sha256sum
+    (bytevector->base16-string (hash:sha256 (string->bytevector seed 
"UTF-8"))))
+
+  ;; certtool.c wants a 56 byte seed for a 2048 bit key.
+  (define size 2048)
+  (define normalized-seed (string-take sha256sum 56))
+
+  (computed-file (string-append seed "-signing-key.pem")
+                 #~(system* #$(file-append gnutls "/bin/certtool")
+                            "--generate-privkey"
+                            "--key-type=rsa"
+                            "--pkcs8"
+                            ;; Use the provable FIPS-PUB186-4 algorithm for
+                            ;; deterministic results.
+                            "--provable"
+                            "--password="
+                            "--no-text"
+                            (string-append "--bits=" #$(number->string size))
+                            (string-append "--seed=" #$normalized-seed)
+                            "--outfile" #$output)))
+
+(define* (make-crx package #:optional (chromium-output "out"))
+  ;; XXX: This is terrible.  We pull Xorg and Chromium just to pack and
+  ;; sign an extension.  This should be implemented with something lighter
+  ;; using the protobuf-based protocol (TODO: where is it documented..?).
+  (define name (package-name package))
+  (define version (package-version package))
+  (define signing-key (make-signing-key name))
+
+  (with-imported-modules '((guix build utils))
+    (computed-file
+     (string-append name "-" version ".crx")
+     #~(begin
+         (use-modules (guix build utils)
+                      (ice-9 ftw)
+                      (srfi srfi-26))
+         (let ((chromium #$(file-append ungoogled-chromium "/bin/chromium"))
+               (xvfb #$(file-append xorg-server "/bin/Xvfb"))
+               (packdir (string-append "/tmp/extension/" #$name)))
+           (mkdir-p (dirname packdir))
+           (copy-recursively (ungexp package chromium-output) packdir)
+           (system (string-append xvfb " :1 &"))
+           (setenv "DISPLAY" ":1")
+           (sleep 2)  ;give Xorg some time to initialize...
+           ;; Chromium stores the current time in the .crx Zip archive.
+           ;; Sidestep that by using "faketime" for determinism.
+           ;; FIXME (core-updates): faketime is missing an absolute reference
+           ;; to 'date', hence the need to set PATH.
+           (setenv "PATH" #$(file-append coreutils "/bin"))
+           (invoke #$(file-append libfaketime "/bin/faketime")
+                   "2000-01-01 00:00:00"
+                   chromium
+                   "--user-data-dir=/tmp/signing-profile"
+                   (string-append "--pack-extension=" packdir)
+                   (string-append "--pack-extension-key=" #$signing-key))
+           (copy-file (string-append packdir ".crx") #$output))))))
+
+(define* (package->chromium-json package #:optional (chromium-output "out"))
+  "Return a derivation that creates a JSON file for PACKAGE, meant to be
+consumed by Chromium to make the installed extension visible."
+
+  (define name (package-name package))
+  (define version (package-version package))
+  (define crx (make-crx package chromium-output))
+
+  (computed-file (string-append name "-" version ".json")
+                 #~(call-with-output-file #$output
+                     (lambda (port)
+                       ;; Documentation for the JSON format can be found in
+                       ;; extensions/common/extension.h and
+                       ;; chrome/browser/extensions/external_provider_impl.cc.
+                       (format port "
+{
+  \"external_crx\": \"~a\",
+  \"external_version\": \"~a\"
+}
+"
+                               #$crx #$version)))))
+
+
+(define (key->der key)
+  "Return a derivation for a file representation of KEY in DER format."
+  (computed-file "der"
+                 #~(system* #$(file-append gnutls "/bin/certtool")
+                            "--load-privkey" #$key
+                            "--pubkey-info"
+                            "--outfile" #$output
+                            "--outder")))
+
+(define (gexp-sha256sum file)
+  "Return a derivation for a base16 representation of the SHA256 checksum
+of FILE."
+  (with-extensions (list guile-gcrypt)
+    #~(begin
+        (use-modules (gcrypt base16) (gcrypt hash))
+        (format #f (bytevector->base16-string (file-sha256 #$file))))))
+
+(define (chromium-json->profile-object json signing-key)
+  "Return a derivation that installs JSON to the destination searched by
+Chromium, using a file name (aka extension ID) derived from SIGNING-KEY."
+  (define der (key->der signing-key))
+  (define checksum (gexp-sha256sum der))
+
+  (with-imported-modules '((guix build utils))
+    (computed-file
+     "chromium-extension"
+     #~(begin
+         (use-modules (guix build utils))
+         (define (base16-string->chromium-base16 str)
+           ;; Translate STR, a hexadecimal string, to a Chromium-style
+           ;; representation using the letters a-p (where a=0, p=15).
+           (define s1 "0123456789abcdef")
+           (define s2 "abcdefghijklmnop")
+           (let loop ((chars (string->list str))
+                      (converted '()))
+             (if (null? chars)
+                 (list->string (reverse converted))
+                 (loop (cdr chars) (cons (string-ref
+                                          s2 (string-index s1 (car chars)))
+                                         converted)))))
+
+         (let ((file-name (base16-string->chromium-base16
+                           (string-take #$checksum 32)))
+               (extension-directory (string-append #$output
+                                                   
"/share/chromium/extensions")))
+           (mkdir-p extension-directory)
+           (symlink #$json (string-append extension-directory "/"
+                                          file-name ".json")))))))
+
+(define* (make-chromium-extension p #:optional (output "out"))
+  "Create a signed \".crx\" file from package P, an unpacked Chromium
+extension, and return a derivation for a package that makes the packed
+extension visible to Chromium when installed to a Guix profile.
+
+OUTPUT can be used to specify which output of P contains the Chromium
+extension directory."
+  (package
+    (inherit p)
+    (name (string-append (package-name p) "-chromium"))
+    (build-system trivial-build-system)
+    (native-inputs '())
+    (inputs
+     `(("extension" ,(chromium-json->profile-object
+                      (package->chromium-json p output)
+                      (make-signing-key (package-name p))))))
+    (propagated-inputs '())
+    (outputs '("out"))
+    (arguments
+     '(#:modules ((guix build utils))
+       #:builder
+       (begin
+         (use-modules (guix build utils))
+         (copy-recursively (assoc-ref %build-inputs "extension")
+                           (assoc-ref %outputs "out")))))))
+
+
+
+(define uassets
+  (let ((commit "95d609786680bf4cf267b1dff3f429af88040da1"))
+    (origin
+      (method git-fetch)
+      (uri (git-reference
+            (url "https://github.com/uBlockOrigin/uAssets.git";)
+            (commit commit)))
+      (file-name (git-file-name "uAssets" (string-take commit 9)))
+      (sha256
+       (base32
+        "070v2g0hyxvqv77b6z404hdlggl0sq2bfhsfl4a84k93p9pwwlrq")))))
+
+(define ublock-origin
+  (package
+    (name "ublock-origin")
+    (version "1.30.8")
+    (home-page "https://github.com/gorhill/uBlock";)
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference (url home-page) (commit version)))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "1y4dq4p4j4qrw6gfdcbpyigqjinqq3jm8r5x9h5ariiv9s8856w7"))))
+    (build-system gnu-build-system)
+    ;; XXX: The xpi and firefox outputs are currently unused, but included
+    ;; for easy testing.
+    (outputs '("xpi" "firefox" "chromium"))
+    (arguments
+     '(#:tests? #f                      ;no tests
+       #:allowed-references ()
+       #:phases
+       (modify-phases (map (lambda (phase)
+                             (assq phase %standard-phases))
+                           '(set-paths unpack patch-source-shebangs))
+         (add-after 'unpack 'link-uassets
+           (lambda* (#:key native-inputs inputs #:allow-other-keys)
+             (symlink (string-append (assoc-ref (or native-inputs inputs)
+                                                "uassets"))
+                      "../uAssets")
+             #t))
+         (add-after 'unpack 'make-files-writable
+           (lambda _
+             ;; The build system copies some files and later tries
+             ;; modifying them.
+             (for-each make-file-writable (find-files "."))
+             #true))
+         (add-after 'patch-source-shebangs 'build-xpi
+           (lambda _
+             (invoke "./tools/make-firefox.sh" "all")))
+         (add-after 'build-xpi 'build-chromium
+           (lambda _
+             (invoke "./tools/make-chromium.sh")))
+         (add-after 'build-chromium 'install
+           (lambda* (#:key outputs #:allow-other-keys)
+             (let ((firefox (assoc-ref outputs "firefox"))
+                   (xpi (assoc-ref outputs "xpi"))
+                   (chromium (assoc-ref outputs "chromium")))
+               (install-file "dist/build/uBlock0.firefox.xpi"
+                             (string-append xpi "/lib/mozilla/extensions"))
+               (copy-recursively "dist/build/uBlock0.firefox" firefox)
+               (copy-recursively "dist/build/uBlock0.chromium" chromium)
+               #true))))))
+    (native-inputs
+     `(("python" ,python-wrapper)
+       ("uassets" ,uassets)
+       ("zip" ,zip)))
+    (synopsis "Block unwanted content from web sites")
+    (description
+     "uBlock Origin is a @dfn{wide spectrum blocker} for IceCat and
+ungoogled-chromium.")
+    (license license:gpl3+)))
+
+(define-public ublock-origin/chromium
+  (make-chromium-extension ublock-origin "chromium"))
-- 
2.28.0