cacerts: refactor, add blacklist option

Previously, the list of CA certificates was generated with a perl script
which is included in curl. As this script is not very flexible, this commit
refactors the expression to use the python script that Debian uses to
generate their CA certificates from Mozilla's trust store in NSS.

[SL: The following was true of the original commit but was backed out
of the cherry pick]:

Additionally, an option was added to the cacerts derivation and the
`security.pki` module to blacklist specific CAs.

(cherry picked from commit 0d59fc1)

pkgs/data/misc/cacert/default.nix

@@ -1,36 +1,60 @@
-{ stdenv, nss, curl, perl }:
+{ stdenv, fetchurl, writeText, nss, python
+, blacklist ? []
+, includeEmail ? false
+}:
+
+with stdenv.lib;
+
+let
+
+  certdata2pem = fetchurl {
+    name = "certdata2pem.py";
+    url = "https://anonscm.debian.org/cgit/collab-maint/ca-certificates.git/plain/mozilla/certdata2pem.py?h=debian/20160104";
+    sha256 = "0bw11mgfrf19qziyvdnq22kirp0nn54lfsanrg5h6djs6ig1c2im";
+  };
+
+in
 
 stdenv.mkDerivation rec {
   name = "nss-cacert-${nss.version}";
 
   src = nss.src;
 
-  postPatch = ''
-    unpackFile ${curl.src};
+  nativeBuildInputs = [ python ];
 
-    # Remove dependency on LWP, curl is enough. Also, since curl here
-    # is working on a local file it will not actually get a 200 OK, so
-    # remove that expectation.
-    substituteInPlace curl-*/lib/mk-ca-bundle.pl \
-      --replace 'use LWP::UserAgent;' "" \
-      --replace ' && $out[0] == 200' ""
-  '';
+  configurePhase = ''
+    ln -s nss/lib/ckfw/builtins/certdata.txt
+
+    cat << EOF > blacklist.txt
+    ${concatStringsSep "\n" (map (c: ''"${c}"'') blacklist)}
+    EOF
 
-  nativeBuildInputs = [ curl perl ];
+    cp ${certdata2pem} certdata2pem.py
+    ${optionalString includeEmail ''
+      # Disable CAs used for mail signing
+      substituteInPlace certdata2pem.py --replace \[\'CKA_TRUST_EMAIL_PROTECTION\'\] '''
+    ''}
+  '';
 
   buildPhase = ''
-    perl curl-*/lib/mk-ca-bundle.pl -d "file://$(pwd)/nss/lib/ckfw/builtins/certdata.txt" ca-bundle.crt
+    python certdata2pem.py | grep -vE '^(!|UNTRUSTED)'
+
+    for cert in *.crt; do
+      echo $cert | cut -d. -f1 | sed -e 's,_, ,g' >> ca-bundle.crt
+      cat $cert >> ca-bundle.crt
+      echo >> ca-bundle.crt
+    done
   '';
 
   installPhase = ''
     mkdir -pv $out/etc/ssl/certs
     cp -v ca-bundle.crt $out/etc/ssl/certs
   '';
 
-  meta = with stdenv.lib; {
+  meta = {
     homepage = http://curl.haxx.se/docs/caextract.html;
     description = "A bundle of X.509 certificates of public Certificate Authorities (CA)";
     platforms = platforms.all;
-    maintainers = with maintainers; [ wkennington ];
+    maintainers = with maintainers; [ wkennington fpletz ];
   };
 }