Add an address-set backend using a bloom filter.

We're going to need this to make our anti-DoS code (see 24902) more
robust.

1 files changed, 33 insertions, 0 deletions

diff --git a/src/common/address_set.h b/src/common/address_set.h
new file mode 100644
index 0000000000..568528c89e
--- /dev/null
+++ b/src/common/address_set.h
@@ -0,0 +1,33 @@
+/* Copyright (c) 2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file addressset.h
+ * \brief Types to handle sets of addresses.
+ *
+ * This module was first written on a semi-emergency basis to improve the
+ * robustness of the anti-DoS module.  As such, it's written in a pretty
+ * conservative way, and should be susceptible to improvement later on.
+ **/
+
+#ifndef TOR_ADDRESS_SET_H
+#define TOR_ADDRESS_SET_H
+
+#include "orconfig.h"
+
+/**
+ * An address_set_t represents a set of tor_addr_t values. The implementation
+ * is probabilistic: false negatives cannot occur but false positives are
+ * possible.
+ */
+typedef struct address_set_t address_set_t;
+struct tor_addr_t;
+
+address_set_t *address_set_new(int max_addresses_guess);
+void address_set_free(address_set_t *set);
+void address_set_add(address_set_t *set, const struct tor_addr_t *addr);
+int address_set_probably_contains(address_set_t *set,
+                                  const struct tor_addr_t *addr);
+
+#endif
+