prop224: Directory cache support

This implements the proposal 224 directory descriptor cache store and lookup
functionalities. Furthermore, it merges the OOM call for the HSDir cache with
current protocol v2 and the new upcoming v3.

Add hs_cache.{c|h} with store/lookup API.

Closes #18572

Signed-off-by: David Goulet <dgoulet@torproject.org>
Signed-off-by: George Kadianakis <desnacked@riseup.net>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/or/hs_descriptor.c b/src/or/hs_descriptor.c
index cdbea76605..9714d52f8c 100644
--- a/src/or/hs_descriptor.c
+++ b/src/or/hs_descriptor.c
@@ -1918,3 +1918,15 @@ hs_descriptor_free(hs_descriptor_t *desc)
   desc_encrypted_data_free_contents(&desc->encrypted_data);
   tor_free(desc);
 }
+
+/* Return the size in bytes of the given plaintext data object. A sizeof() is
+ * not enough because the object contains pointers and the encrypted blob.
+ * This is particularly useful for our OOM subsystem that tracks the HSDir
+ * cache size for instance. */
+size_t
+hs_desc_plaintext_obj_size(const hs_desc_plaintext_data_t *data)
+{
+  tor_assert(data);
+  return (sizeof(*data) + sizeof(*data->signing_key_cert) +
+          data->encrypted_blob_size);
+}