Implement HKP get operation (Closes #139)

Allow mentors to act as a keyserver.
Example: gpg --keyserver hkps://mentors.debian.net --recv-keys 0x1234567

debexpo/keyring/views.py

+#   views.py - keyring view classes
+#
+#   This file is part of debexpo
+#   https://salsa.debian.org/mentors.debian.net-team/debexpo
+#
+#   Copyright © 2021 Baptiste Beauplat <lyknode@debian.org>
+#
+#   Permission is hereby granted, free of charge, to any person
+#   obtaining a copy of this software and associated documentation
+#   files (the "Software"), to deal in the Software without
+#   restriction, including without limitation the rights to use,
+#   copy, modify, merge, publish, distribute, sublicense, and/or sell
+#   copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following
+#   conditions:
+#
+#   The above copyright notice and this permission notice shall be
+#   included in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+#   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+#   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+#   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+#   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+#   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+#   OTHER DEALINGS IN THE SOFTWARE.
+
+from django.views.generic import View
+from django.views.generic.detail import BaseDetailView
+from django.http import HttpResponseServerError, HttpResponse, \
+                        HttpResponseBadRequest
+from django.shortcuts import get_object_or_404
+
+from debexpo.keyring.models import Key
+
+
+class HKPSearchView(BaseDetailView):
+    model = Key
+
+    def get(self, request, *args, **kwargs):
+        if 'search' not in self.request.GET:
+            return HttpResponseBadRequest("Missing 'search' query string")
+
+        try:
+            return super().get(request, *args, **kwargs)
+        except Key.MultipleObjectsReturned:
+            return HttpResponseServerError('Multiple matches found', status=500)
+
+    def get_object(self, queryset=None):
+        key_id = self.request.GET['search'].replace('0x', '')
+
+        return get_object_or_404(Key, fingerprint__endswith=key_id)
+
+    def render_to_response(self, context, **response_kwargs):
+        return HttpResponse(self.object.key + '\n')
+
+
+class HKPView(View):
+    def get(self, request, *args, **kwargs):
+        if 'op' not in self.request.GET:
+            return HttpResponseBadRequest("Missing 'op' query string")
+
+        if self.request.GET['op'] == 'get':
+            return HKPSearchView.as_view()(request)
+        else:
+            return HttpResponseServerError('Not Implemented', status=501)

debexpo/urls.py

@@ -41,6 +41,7 @@ from debexpo.base.views import index, contact, intro_reviewers, \
     intro_maintainers, qa, sponsor_overview, sponsor_guidelines, sponsor_rfs
 from debexpo.accounts.views import register, profile, EmailChangeConfirmView
 from debexpo.accounts.forms import PasswordResetForm
+from debexpo.keyring.views import HKPView
 from debexpo.packages.views import package, packages, packages_my, \
     PackagesFeed, sponsor_package, delete_package, delete_upload, \
     PackageViewSet, PackageUploadViewSet
@@ -167,6 +168,9 @@ urlpatterns = [
     url(r'^accounts/$', lambda request: HttpResponsePermanentRedirect(
         reverse('profile')), name='accounts'),
 
+    # HPK interface
+    url(r'^pks/lookup$', HKPView.as_view(), name='hkp'),
+
     # Repository
     url(r'^debian/(?P<path>.*)$', serve, {
         'document_root': settings.REPOSITORY,