pull: Add support for http-headers option

Some deployments may want to gate access to content based on things
like OAuth.  In this model, the client system would normally compute a
token and pass it to the server via an API.

We could theoretically support this in the remote config too, but
that'd be a bit weird for OAuth as the information is dynamic.
Therefore this cleans up the code a little bit to more clearly handle
the case that the fetcher is initialized from both remote config
data plus pull options.

Closes: #574
Approved by: giuseppe

tests/test-remote-headers.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+#
+# Copyright (C) 2016 Red Hat, Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+set -euo pipefail
+
+echo '1..2'
+
+. $(dirname $0)/libtest.sh
+
+setup_fake_remote_repo1 "archive" "" \
+  "--expected-header foo=bar --expected-header baz=badger"
+
+assert_fail (){
+  set +e
+  $@
+  if [ $? = 0 ] ; then
+    echo 1>&2 "$@ did not fail"; exit 1
+  fi
+  set -euo pipefail
+}
+
+cd ${test_tmpdir}
+rm repo -rf
+mkdir repo
+${CMD_PREFIX} ostree --repo=repo init
+${CMD_PREFIX} ostree --repo=repo remote add --set=gpg-verify=false origin $(cat httpd-address)/ostree/gnomerepo
+
+# Sanity check the setup, without headers the pull should fail
+assert_fail ${CMD_PREFIX} ostree --repo=repo pull origin main
+
+echo "ok, setup done"
+
+# Now pull should succeed now
+${CMD_PREFIX} ostree --repo=repo pull --http-header foo=bar --http-header baz=badger origin main
+
+echo "ok, pull succeeded"