lib/pull: Default checksum for archive mirror, add TRUSTED_HTTP flag

I now think commit fab1e113db was a mistake;
because it breaks the mental model that at least I'd built up that "local repos
don't have checksums verified, HTTP does".

For example, a problem with this is (with that mental model in place) it's easy
for people who set up mirrors like this to then do local pulls, and at that
point we've done a deployment with no checksum verification.

Further, since then we did PR #671 AKA commit 3d38f03 which is really most of
the speed hit.

So let's switch the default even for this case to doing checksum verification,
and add `ostree pull --http-trusted`. People who are in situations where they
know they want this can find it and turn it on.

Closes: https://github.com/ostreedev/ostree/issues/1211

Closes: #1212
Approved by: jlebon

src/libostree/ostree-repo-pull.c

@@ -1006,12 +1006,15 @@ content_fetch_on_complete (GObject        *object,
   const gboolean verifying_bareuseronly =
     (pull_data->importflags & _OSTREE_REPO_IMPORT_FLAGS_VERIFY_BAREUSERONLY) > 0;
 
-  /* If we're mirroring and writing into an archive repo, we can directly copy
-   * the content rather than paying the cost of exploding it, checksumming, and
-   * re-gzip.
+  /* If we're mirroring and writing into an archive repo, and both checksum and
+   * bareuseronly are turned off, we can directly copy the content rather than
+   * paying the cost of exploding it, checksumming, and re-gzip.
    */
-  if (pull_data->is_mirror && pull_data->repo->mode == OSTREE_REPO_MODE_ARCHIVE
-      && !verifying_bareuseronly)
+  const gboolean mirroring_into_archive =
+    pull_data->is_mirror && pull_data->repo->mode == OSTREE_REPO_MODE_ARCHIVE;
+  const gboolean import_trusted = !verifying_bareuseronly &&
+    (pull_data->importflags & _OSTREE_REPO_IMPORT_FLAGS_TRUSTED) > 0;
+  if (mirroring_into_archive && import_trusted)
     {
       gboolean have_object;
       if (!ostree_repo_has_object (pull_data->repo, OSTREE_OBJECT_TYPE_FILE, checksum,
@@ -3541,9 +3544,13 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
     }
   else
     {
-      /* We don't add _IMPORT_FLAGS_TRUSTED for http repos;
-       * OSTREE_REPO_PULL_FLAGS_UNTRUSTED only matters for local repos.
+      /* For non-local repos, we require the TRUSTED_HTTP pull flag to map to
+       * the TRUSTED object import flag. In practice we don't do object imports
+       * for HTTP, but it's easiest to use one set of flags between HTTP and
+       * local imports.
        */
+      if (flags & OSTREE_REPO_PULL_FLAGS_TRUSTED_HTTP)
+        pull_data->importflags |= _OSTREE_REPO_IMPORT_FLAGS_TRUSTED;
     }
 
   /* We can't use static deltas if pulling into an archive repo. */