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, 27 insertions, 36 deletions

diff --git a/src/or/rendcache.c b/src/or/rendcache.c
index 709aaffdee..bf43407289 100644
--- a/src/or/rendcache.c
+++ b/src/or/rendcache.c
@@ -86,7 +86,7 @@ rend_cache_get_total_allocation(void)
 }
 
 /** Decrement the total bytes attributed to the rendezvous cache by n. */
-STATIC void
+void
 rend_cache_decrement_allocation(size_t n)
 {
   static int have_underflowed = 0;
@@ -103,7 +103,7 @@ rend_cache_decrement_allocation(size_t n)
 }
 
 /** Increase the total bytes attributed to the rendezvous cache by n. */
-STATIC void
+void
 rend_cache_increment_allocation(size_t n)
 {
   static int have_overflowed = 0;
@@ -462,45 +462,36 @@ rend_cache_intro_failure_note(rend_intro_point_failure_t failure,
 }
 
 /** Remove all old v2 descriptors and those for which this hidden service
- * directory is not responsible for any more.
- *
- * If at all possible, remove at least <b>force_remove</b> bytes of data.
- */
-void
-rend_cache_clean_v2_descs_as_dir(time_t now, size_t force_remove)
+ * directory is not responsible for any more. The cutoff is the time limit for
+ * which we want to keep the cache entry. In other words, any entry created
+ * before will be removed. */
+size_t
+rend_cache_clean_v2_descs_as_dir(time_t cutoff)
 {
   digestmap_iter_t *iter;
-  time_t cutoff = now - REND_CACHE_MAX_AGE - REND_CACHE_MAX_SKEW;
-  const int LAST_SERVED_CUTOFF_STEP = 1800;
-  time_t last_served_cutoff = cutoff;
   size_t bytes_removed = 0;
-  do {
-    for (iter = digestmap_iter_init(rend_cache_v2_dir);
-         !digestmap_iter_done(iter); ) {
-      const char *key;
-      void *val;
-      rend_cache_entry_t *ent;
-      digestmap_iter_get(iter, &key, &val);
-      ent = val;
-      if (ent->parsed->timestamp < cutoff ||
-          ent->last_served < last_served_cutoff) {
-        char key_base32[REND_DESC_ID_V2_LEN_BASE32 + 1];
-        base32_encode(key_base32, sizeof(key_base32), key, DIGEST_LEN);
-        log_info(LD_REND, "Removing descriptor with ID '%s' from cache",
-                 safe_str_client(key_base32));
-        bytes_removed += rend_cache_entry_allocation(ent);
-        iter = digestmap_iter_next_rmv(rend_cache_v2_dir, iter);
-        rend_cache_entry_free(ent);
-      } else {
-        iter = digestmap_iter_next(rend_cache_v2_dir, iter);
-      }
+
+  for (iter = digestmap_iter_init(rend_cache_v2_dir);
+       !digestmap_iter_done(iter); ) {
+    const char *key;
+    void *val;
+    rend_cache_entry_t *ent;
+    digestmap_iter_get(iter, &key, &val);
+    ent = val;
+    if (ent->parsed->timestamp < cutoff) {
+      char key_base32[REND_DESC_ID_V2_LEN_BASE32 + 1];
+      base32_encode(key_base32, sizeof(key_base32), key, DIGEST_LEN);
+      log_info(LD_REND, "Removing descriptor with ID '%s' from cache",
+               safe_str_client(key_base32));
+      bytes_removed += rend_cache_entry_allocation(ent);
+      iter = digestmap_iter_next_rmv(rend_cache_v2_dir, iter);
+      rend_cache_entry_free(ent);
+    } else {
+      iter = digestmap_iter_next(rend_cache_v2_dir, iter);
     }
+  }
 
-    /* In case we didn't remove enough bytes, advance the cutoff a little. */
-    last_served_cutoff += LAST_SERVED_CUTOFF_STEP;
-    if (last_served_cutoff > now)
-      break;
-  } while (bytes_removed < force_remove);
+  return bytes_removed;
 }
 
 /** Lookup in the client cache the given service ID <b>query</b> for