Nick Mathewson
--- a/src/or/consdiffmgr.c 0 → 100644
+++ b/src/or/consdiffmgr.c 0 → 100644
+ * If true, we have learned at least one new consensus since the
+ * consensus cache was last up-to-date.
+ */
+static int cdm_cache_dirty = 0;
+/**
+ * If true, we have scanned the cache to update our hashtable of diffs.
+ */
+static int cdm_cache_loaded = 0;
+
+/**
+ * Possible status values for cdm_diff_t.cdm_diff_status
+ *
+ * @{ */
+#define CDM_DIFF_PRESENT 1
+#define CDM_DIFF_IN_PROGRESS 2
+#define CDM_DIFF_ERROR 3
--- a/src/or/consdiffmgr.c 0 → 100644
+++ b/src/or/consdiffmgr.c 0 → 100644
+  memcpy(search.from_sha3, from_sha3, DIGEST256_LEN);
+  ent = HT_FIND(cdm_diff_ht, &cdm_diff_ht, &search);
+  if (ent) {
+    tor_assert_nonfatal(ent->cdm_diff_status != CDM_DIFF_PRESENT);
+    return 1;
+  }
+  ent = cdm_diff_new(flav, from_sha3, target_sha3);
+  ent->cdm_diff_status = CDM_DIFF_IN_PROGRESS;
+  HT_INSERT(cdm_diff_ht, &cdm_diff_ht, ent);
+  return 0;
+}
+
+/**
+ * Update the status of the diff of type <b>flav</b> between consensuses with
+ * the two provided SHA3-256 digests, so that its status becomes
+ * <b>status</b>, and its value becomes the (optional) <b>handle</b>.
--- a/src/or/consdiffmgr.c 0 → 100644
+++ b/src/or/consdiffmgr.c 0 → 100644
+ * Return 0 on success and -1 on failure.
+ */
+int
+consdiffmgr_add_consensus(const char *consensus,
+                          const networkstatus_t *as_parsed)
+{
+  if (BUG(consensus == NULL) || BUG(as_parsed == NULL))
+    return -1; // LCOV_EXCL_LINE
+  if (BUG(as_parsed->type != NS_TYPE_CONSENSUS))
+    return -1; // LCOV_EXCL_LINE
+
+  const consensus_flavor_t flavor = as_parsed->flavor;
+  const time_t valid_after = as_parsed->valid_after;
+
+  if (valid_after < approx_time() - 3600 * consdiff_cfg.cache_max_age_hours) {
+    log_info(LD_DIRSERV, "We don't care about this one; it's too old.");
--- a/src/or/consdiffmgr.c 0 → 100644
+++ b/src/or/consdiffmgr.c 0 → 100644
+    consensus_cache_entry_incref(obj);
+    r = consensus_cache_entry_get_body(obj, &body, &bodylen);
+    if (r == 0) {
+      crypto_digest256((char *)sha3_received, (const char *)body, bodylen,
+                       DIGEST_SHA3_256);
+    }
+    consensus_cache_entry_decref(obj);
+    if (r < 0)
+      continue;
+
+    if (fast_memneq(sha3_received, sha3_expected, DIGEST256_LEN)) {
+      problems = 1;
+      consensus_cache_entry_mark_for_removal(obj);
+      continue;
+    }
+