Merge branch 'maint-0.2.9' into maint-0.3.1

src/test/include.am

@@ -83,6 +83,7 @@ src_test_test_SOURCES = \
 	src/test/test_accounting.c \
 	src/test/test_addr.c \
 	src/test/test_address.c \
+	src/test/test_address_set.c \
 	src/test/test_buffers.c \
 	src/test/test_cell_formats.c \
 	src/test/test_cell_queue.c \
@@ -105,6 +106,7 @@ src_test_test_SOURCES = \
 	src/test/test_controller_events.c \
 	src/test/test_crypto.c \
 	src/test/test_crypto_openssl.c \
+	src/test/test_dos.c \
 	src/test/test_data.c \
 	src/test/test_dir.c \
 	src/test/test_dir_common.c \

src/test/test.c

@@ -912,6 +912,24 @@ test_geoip(void *arg)
   tt_str_op(entry_stats_2,OP_EQ, s);
   tor_free(s);
 
+  /* Test the OOM handler. Add a client, run the OOM. */
+  geoip_entry_stats_init(now);
+  SET_TEST_ADDRESS(100);
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &addr, NULL,
+                         now - (12 * 60 * 60));
+  /* We've seen this 12 hours ago. Run the OOM, it should clean the entry
+   * because it is above the minimum cutoff of 4 hours. */
+  size_t bytes_removed = geoip_client_cache_handle_oom(now, 1000);
+  tt_size_op(bytes_removed, OP_GT, 0);
+
+  /* Do it again but this time with an entry with a lower cutoff. */
+  geoip_entry_stats_init(now);
+  SET_TEST_ADDRESS(100);
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &addr, NULL,
+                         now - (3 * 60 * 60));
+  bytes_removed = geoip_client_cache_handle_oom(now, 1000);
+  tt_size_op(bytes_removed, OP_EQ, 0);
+
   /* Stop collecting entry statistics. */
   geoip_entry_stats_term();
   get_options_mutable()->EntryStatistics = 0;
@@ -1182,6 +1200,7 @@ struct testgroup_t testgroups[] = {
   { "accounting/", accounting_tests },
   { "addr/", addr_tests },
   { "address/", address_tests },
+  { "address_set/", address_set_tests },
   { "buffer/", buffer_tests },
   { "cellfmt/", cell_format_tests },
   { "cellqueue/", cell_queue_tests },
@@ -1204,6 +1223,7 @@ struct testgroup_t testgroups[] = {
   { "control/event/", controller_event_tests },
   { "crypto/", crypto_tests },
   { "crypto/openssl/", crypto_openssl_tests },
+  { "dos/", dos_tests },
   { "dir/", dir_tests },
   { "dir_handle_get/", dir_handle_get_tests },
   { "dir/md/", microdesc_tests },

src/test/test.h

@@ -177,6 +177,7 @@ extern const struct testcase_setup_t ed25519_test_setup;
 extern struct testcase_t accounting_tests[];
 extern struct testcase_t addr_tests[];
 extern struct testcase_t address_tests[];
+extern struct testcase_t address_set_tests[];
 extern struct testcase_t buffer_tests[];
 extern struct testcase_t cell_format_tests[];
 extern struct testcase_t cell_queue_tests[];
@@ -199,6 +200,7 @@ extern struct testcase_t controller_tests[];
 extern struct testcase_t controller_event_tests[];
 extern struct testcase_t crypto_tests[];
 extern struct testcase_t crypto_openssl_tests[];
+extern struct testcase_t dos_tests[];
 extern struct testcase_t dir_tests[];
 extern struct testcase_t dir_handle_get_tests[];
 extern struct testcase_t entryconn_tests[];

src/test/test_address_set.c

@@ -0,0 +1,174 @@
+/* Copyright (c) 2017, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "or.h"
+#include "address_set.h"
+#include "microdesc.h"
+#include "networkstatus.h"
+#include "nodelist.h"
+#include "routerlist.h"
+#include "torcert.h"
+
+#include "test.h"
+
+static networkstatus_t *dummy_ns = NULL;
+static networkstatus_t *
+mock_networkstatus_get_latest_consensus(void)
+{
+  return dummy_ns;
+}
+
+static networkstatus_t *
+mock_networkstatus_get_latest_consensus_by_flavor(consensus_flavor_t f)
+{
+  tor_assert(f == FLAV_MICRODESC);
+  return dummy_ns;
+}
+
+/* Number of address a single node_t can have. Default to the production
+ * value. This is to control the size of the bloom filter. */
+static int addr_per_node = 2;
+static int
+mock_get_estimated_address_per_node(void)
+{
+  return addr_per_node;
+}
+
+static void
+test_contains(void *arg)
+{
+  int ret;
+  address_set_t *set = NULL;
+
+  (void) arg;
+
+  /* Setup an IPv4 and IPv6 addresses. */
+  tor_addr_t addr_v6;
+  tor_addr_parse(&addr_v6, "1:2:3:4::");
+  tor_addr_t addr_v4;
+  tor_addr_parse(&addr_v4, "42.42.42.42");
+  uint32_t ipv4h = tor_addr_to_ipv4h(&addr_v4);
+
+  /* Make it very big so the chance of failing the contain test will be
+   * extremely rare. */
+  set = address_set_new(1024);
+  tt_assert(set);
+
+  /* Add and lookup IPv6. */
+  address_set_add(set, &addr_v6);
+  ret = address_set_probably_contains(set, &addr_v6);
+  tt_int_op(ret, OP_EQ, 1);
+
+  /* Add and lookup IPv4. */
+  address_set_add_ipv4h(set, ipv4h);
+  ret = address_set_probably_contains(set, &addr_v4);
+  tt_int_op(ret, OP_EQ, 1);
+
+  /* Try a lookup of rubbish. */
+  tor_addr_t dummy_addr;
+  memset(&dummy_addr, 'A', sizeof(dummy_addr));
+  dummy_addr.family = AF_INET;
+  ret = address_set_probably_contains(set, &dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+  dummy_addr.family = AF_INET6;
+  ret = address_set_probably_contains(set, &dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+
+ done:
+  address_set_free(set);
+}
+
+static void
+test_nodelist(void *arg)
+{
+  int ret;
+  routerstatus_t *rs = NULL; microdesc_t *md = NULL; routerinfo_t *ri = NULL;
+
+  (void) arg;
+
+  MOCK(networkstatus_get_latest_consensus,
+       mock_networkstatus_get_latest_consensus);
+  MOCK(networkstatus_get_latest_consensus_by_flavor,
+       mock_networkstatus_get_latest_consensus_by_flavor);
+  MOCK(get_estimated_address_per_node,
+       mock_get_estimated_address_per_node);
+
+  dummy_ns = tor_malloc_zero(sizeof(*dummy_ns));
+  dummy_ns->flavor = FLAV_MICRODESC;
+  dummy_ns->routerstatus_list = smartlist_new();
+
+  tor_addr_t addr_v4, addr_v6, dummy_addr;
+  tor_addr_parse(&addr_v4, "42.42.42.42");
+  uint32_t ipv4h = tor_addr_to_ipv4h(&addr_v4);
+  tor_addr_parse(&addr_v6, "1:2:3:4::");
+  memset(&dummy_addr, 'A', sizeof(dummy_addr));
+
+  /* This will make the nodelist bloom filter very large
+   * (the_nodelist->node_addrs) so we will fail the contain test rarely. */
+  addr_per_node = 1024;
+
+  /* No node no nothing. The lookups should be empty. */
+  nodelist_set_consensus(dummy_ns);
+
+  /* The address set should be empty. */
+  ret = nodelist_probably_contains_address(&addr_v4);
+  tt_int_op(ret, OP_EQ, 0);
+  ret = nodelist_probably_contains_address(&addr_v6);
+  tt_int_op(ret, OP_EQ, 0);
+  dummy_addr.family = AF_INET;
+  ret = nodelist_probably_contains_address(&dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+  dummy_addr.family = AF_INET6;
+  ret = nodelist_probably_contains_address(&dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+
+  md = tor_malloc_zero(sizeof(*md));
+  ri = tor_malloc_zero(sizeof(*ri));
+  rs = tor_malloc_zero(sizeof(*rs));
+  crypto_rand(rs->identity_digest, sizeof(rs->identity_digest));
+  crypto_rand(md->digest, sizeof(md->digest));
+  memcpy(rs->descriptor_digest, md->digest, DIGEST256_LEN);
+
+  /* Setup the rs, ri and md addresses. */
+  rs->addr = ipv4h;
+  tor_addr_parse(&rs->ipv6_addr, "1:2:3:4::");
+  ri->addr = ipv4h;
+  tor_addr_parse(&ri->ipv6_addr, "1:2:3:4::");
+  tor_addr_parse(&md->ipv6_addr, "1:2:3:4::");
+
+  /* Add the rs to the consensus becoming a node_t. */
+  smartlist_add(dummy_ns->routerstatus_list, rs);
+  nodelist_set_consensus(dummy_ns);
+
+  /* At this point, the address set should be initialized in the nodelist and
+   * we should be able to lookup. */
+  ret = nodelist_probably_contains_address(&addr_v4);
+  tt_int_op(ret, OP_EQ, 1);
+  ret = nodelist_probably_contains_address(&addr_v6);
+  tt_int_op(ret, OP_EQ, 1);
+  /* Lookup unknown address. */
+  dummy_addr.family = AF_INET;
+  ret = nodelist_probably_contains_address(&dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+  dummy_addr.family = AF_INET6;
+  ret = nodelist_probably_contains_address(&dummy_addr);
+  tt_int_op(ret, OP_EQ, 0);
+
+ done:
+  routerstatus_free(rs); routerinfo_free(ri); microdesc_free(md);
+  smartlist_clear(dummy_ns->routerstatus_list);
+  networkstatus_vote_free(dummy_ns);
+  UNMOCK(networkstatus_get_latest_consensus);
+  UNMOCK(networkstatus_get_latest_consensus_by_flavor);
+  UNMOCK(get_estimated_address_per_node);
+}
+
+struct testcase_t address_set_tests[] = {
+  { "contains", test_contains, TT_FORK,
+    NULL, NULL },
+  { "nodelist", test_nodelist, TT_FORK,
+    NULL, NULL },
+
+  END_OF_TESTCASES
+};
+

src/test/test_dos.c

@@ -0,0 +1,497 @@
+/* Copyright (c) 2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#define DOS_PRIVATE
+#define TOR_CHANNEL_INTERNAL_
+#define CIRCUITLIST_PRIVATE
+
+#include "or.h"
+#include "dos.h"
+#include "circuitlist.h"
+#include "geoip.h"
+#include "channel.h"
+#include "microdesc.h"
+#include "networkstatus.h"
+#include "nodelist.h"
+#include "routerlist.h"
+#include "test.h"
+#include "log_test_helpers.h"
+
+static networkstatus_t *dummy_ns = NULL;
+static networkstatus_t *
+mock_networkstatus_get_latest_consensus(void)
+{
+  return dummy_ns;
+}
+
+static networkstatus_t *
+mock_networkstatus_get_latest_consensus_by_flavor(consensus_flavor_t f)
+{
+  tor_assert(f == FLAV_MICRODESC);
+  return dummy_ns;
+}
+
+/* Number of address a single node_t can have. Default to the production
+ * value. This is to control the size of the bloom filter. */
+static int addr_per_node = 2;
+static int
+mock_get_estimated_address_per_node(void)
+{
+  return addr_per_node;
+}
+
+static unsigned int
+mock_enable_dos_protection(const networkstatus_t *ns)
+{
+  (void) ns;
+  return 1;
+}
+
+/** Test that the connection tracker of the DoS subsystem will block clients
+ *  who try to establish too many connections */
+static void
+test_dos_conn_creation(void *arg)
+{
+  (void) arg;
+
+  MOCK(get_param_cc_enabled, mock_enable_dos_protection);
+  MOCK(get_param_conn_enabled, mock_enable_dos_protection);
+
+  /* Initialize test data */
+  or_connection_t or_conn;
+  time_t now = 1281533250; /* 2010-08-11 13:27:30 UTC */
+  tt_int_op(AF_INET,OP_EQ, tor_addr_parse(&or_conn.real_addr,
+                                          "18.0.0.1"));
+  tor_addr_t *addr = &or_conn.real_addr;
+
+  /* Get DoS subsystem limits */
+  dos_init();
+  uint32_t max_concurrent_conns = get_param_conn_max_concurrent_count(NULL);
+
+  /* Introduce new client */
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, addr, NULL, now);
+  { /* Register many conns from this client but not enough to get it blocked */
+    unsigned int i;
+    for (i = 0; i < max_concurrent_conns; i++) {
+      dos_new_client_conn(&or_conn);
+    }
+  }
+
+  /* Check that new conns are still permitted */
+  tt_int_op(DOS_CONN_DEFENSE_NONE, OP_EQ,
+            dos_conn_addr_get_defense_type(addr));
+
+  /* Register another conn and check that new conns are not allowed anymore */
+  dos_new_client_conn(&or_conn);
+  tt_int_op(DOS_CONN_DEFENSE_CLOSE, OP_EQ,
+            dos_conn_addr_get_defense_type(addr));
+
+  /* Close a client conn and see that a new conn will be permitted again */
+  dos_close_client_conn(&or_conn);
+  tt_int_op(DOS_CONN_DEFENSE_NONE, OP_EQ,
+            dos_conn_addr_get_defense_type(addr));
+
+  /* Register another conn and see that defense measures get reactivated */
+  dos_new_client_conn(&or_conn);
+  tt_int_op(DOS_CONN_DEFENSE_CLOSE, OP_EQ,
+            dos_conn_addr_get_defense_type(addr));
+
+ done:
+  dos_free_all();
+}
+
+/** Helper mock: Place a fake IP addr for this channel in <b>addr_out</b> */
+static int
+mock_channel_get_addr_if_possible(channel_t *chan, tor_addr_t *addr_out)
+{
+  (void)chan;
+  tt_int_op(AF_INET,OP_EQ, tor_addr_parse(addr_out, "18.0.0.1"));
+  return 1;
+
+ done:
+  return 0;
+}
+
+/** Test that the circuit tracker of the DoS subsystem will block clients who
+ *  try to establish too many circuits. */
+static void
+test_dos_circuit_creation(void *arg)
+{
+  (void) arg;
+  unsigned int i;
+
+  MOCK(get_param_cc_enabled, mock_enable_dos_protection);
+  MOCK(get_param_conn_enabled, mock_enable_dos_protection);
+  MOCK(channel_get_addr_if_possible,
+       mock_channel_get_addr_if_possible);
+
+  /* Initialize channels/conns/circs that will be used */
+  channel_t *chan = tor_malloc_zero(sizeof(channel_t));
+  channel_init(chan);
+  chan->is_client = 1;
+
+  /* Initialize test data */
+  or_connection_t or_conn;
+  time_t now = 1281533250; /* 2010-08-11 13:27:30 UTC */
+  tt_int_op(AF_INET,OP_EQ, tor_addr_parse(&or_conn.real_addr,
+                                          "18.0.0.1"));
+  tor_addr_t *addr = &or_conn.real_addr;
+
+  /* Get DoS subsystem limits */
+  dos_init();
+  uint32_t max_circuit_count = get_param_cc_circuit_burst(NULL);
+  uint32_t min_conc_conns_for_cc =
+    get_param_cc_min_concurrent_connection(NULL);
+
+  /* Introduce new client and establish enough connections to activate the
+   * circuit counting subsystem */
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, addr, NULL, now);
+  for (i = 0; i < min_conc_conns_for_cc ; i++) {
+    dos_new_client_conn(&or_conn);
+  }
+
+  /* Register new circuits for this client and conn, but not enough to get
+   * detected as dos */
+  for (i=0; i < max_circuit_count-1; i++) {
+    dos_cc_new_create_cell(chan);
+  }
+  /* see that we didn't get detected for dosing */
+  tt_int_op(DOS_CC_DEFENSE_NONE, OP_EQ, dos_cc_get_defense_type(chan));
+
+  /* Register another CREATE cell that will push us over the limit. Check that
+   * the cell gets refused. */
+  dos_cc_new_create_cell(chan);
+  tt_int_op(DOS_CC_DEFENSE_REFUSE_CELL, OP_EQ, dos_cc_get_defense_type(chan));
+
+  /* TODO: Wait a few seconds before sending the cell, and check that the
+     buckets got refilled properly. */
+  /* TODO: Actually send a Tor cell (instead of calling the DoS function) and
+   * check that it will get refused */
+
+ done:
+  tor_free(chan);
+  dos_free_all();
+}
+
+/** Test that the DoS subsystem properly refills the circuit token buckets. */
+static void
+test_dos_bucket_refill(void *arg)
+{
+  (void) arg;
+  int i;
+  /* For this test, this variable is set to the current circ count of the token
+   * bucket. */
+  uint32_t current_circ_count;
+
+  MOCK(get_param_cc_enabled, mock_enable_dos_protection);
+  MOCK(get_param_conn_enabled, mock_enable_dos_protection);
+  MOCK(channel_get_addr_if_possible,
+       mock_channel_get_addr_if_possible);
+
+  time_t now = 1281533250; /* 2010-08-11 13:27:30 UTC */
+  update_approx_time(now);
+
+  /* Initialize channels/conns/circs that will be used */
+  channel_t *chan = tor_malloc_zero(sizeof(channel_t));
+  channel_init(chan);
+  chan->is_client = 1;
+  or_connection_t or_conn;
+  tt_int_op(AF_INET,OP_EQ, tor_addr_parse(&or_conn.real_addr,
+                                          "18.0.0.1"));
+  tor_addr_t *addr = &or_conn.real_addr;
+
+  /* Initialize DoS subsystem and get relevant limits */
+  dos_init();
+  uint32_t max_circuit_count = get_param_cc_circuit_burst(NULL);
+  uint64_t circ_rate = get_circuit_rate_per_second();
+  /* Check that the circuit rate is a positive number and smaller than the max
+   * circuit count */
+  tt_u64_op(circ_rate, OP_GT, 1);
+  tt_u64_op(circ_rate, OP_LT, max_circuit_count);
+
+  /* Register this client */
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, addr, NULL, now);
+  dos_new_client_conn(&or_conn);
+
+  /* Fetch this client from the geoip cache and get its DoS structs */
+  clientmap_entry_t *entry = geoip_lookup_client(addr, NULL,
+                                                 GEOIP_CLIENT_CONNECT);
+  tt_assert(entry);
+  dos_client_stats_t* dos_stats = &entry->dos_stats;
+  /* Check that the circuit bucket is still uninitialized */
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, 0);
+
+  /* Send a create cell: then check that the circ token bucket got initialized
+   * and one circ was subtracted. */
+  dos_cc_new_create_cell(chan);
+  current_circ_count = max_circuit_count - 1;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send 29 more CREATEs and ensure that the bucket is missing 30
+   * tokens */
+  for (i=0; i < 29; i++) {
+   dos_cc_new_create_cell(chan);
+   current_circ_count--;
+  }
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* OK! Progress time forward one sec, refill the bucket and check that the
+   * refill happened correctly. */
+  now += 1;
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  /* check refill */
+  current_circ_count += circ_rate;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+   dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now progress time a week forward, and check that the token bucket does not
+   * have more than max_circs allowance, even tho we let it simmer for so
+   * long. */
+  now += 604800; /* a week */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now use a very large time, and check that the token bucket does not have
+   * more than max_circs allowance, even tho we let it simmer for so long. */
+  now = INT32_MAX; /* 2038? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now use a very small time, and check that the token bucket has exactly
+   * the max_circs allowance, because backward clock jumps are rare. */
+  now = INT32_MIN; /* 19?? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Progress time forward one sec again, refill the bucket and check that the
+   * refill happened correctly. */
+  now += 1;
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  /* check refill */
+  current_circ_count += circ_rate;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now use a very large time (again), and check that the token bucket does
+   * not have more than max_circs allowance, even tho we let it simmer for so
+   * long. */
+  now = INT32_MAX; /* 2038? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* This code resets the time to zero with 32-bit time_t, which triggers the
+   * code that initialises the bucket. */
+#if SIZEOF_TIME_T == 8
+  /* Now use a very very small time, and check that the token bucket has
+   * exactly the max_circs allowance, because backward clock jumps are rare.
+   */
+  now = (time_t)INT64_MIN; /* ???? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Progress time forward one sec again, refill the bucket and check that the
+   * refill happened correctly. */
+  now += 1;
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  /* check refill */
+  current_circ_count += circ_rate;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now use a very very small time, and check that the token bucket has
+   * exactly the max_circs allowance, because backward clock jumps are rare.
+   */
+  now = (time_t)INT64_MIN; /* ???? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now use a very very large time, and check that the token bucket does not
+   * have more than max_circs allowance, even tho we let it simmer for so
+   * long. */
+  now = (time_t)INT64_MAX; /* ???? */
+  update_approx_time(now);
+  cc_stats_refill_bucket(&dos_stats->cc_stats, addr);
+  current_circ_count += max_circuit_count;
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+
+  /* Now send as many CREATE cells as needed to deplete our token bucket
+   * completely */
+  for (; current_circ_count != 0; current_circ_count--) {
+    dos_cc_new_create_cell(chan);
+  }
+  tt_uint_op(current_circ_count, OP_EQ, 0);
+  tt_uint_op(dos_stats->cc_stats.circuit_bucket, OP_EQ, current_circ_count);
+#endif
+
+ done:
+  tor_free(chan);
+  dos_free_all();
+}
+
+/* Test if we avoid counting a known relay. */
+static void
+test_known_relay(void *arg)
+{
+  clientmap_entry_t *entry = NULL;
+  routerstatus_t *rs = NULL; microdesc_t *md = NULL; routerinfo_t *ri = NULL;
+
+  (void) arg;
+
+  MOCK(networkstatus_get_latest_consensus,
+       mock_networkstatus_get_latest_consensus);
+  MOCK(networkstatus_get_latest_consensus_by_flavor,
+       mock_networkstatus_get_latest_consensus_by_flavor);
+  MOCK(get_estimated_address_per_node,
+       mock_get_estimated_address_per_node);
+  MOCK(get_param_cc_enabled, mock_enable_dos_protection);
+
+  dos_init();
+
+  dummy_ns = tor_malloc_zero(sizeof(*dummy_ns));
+  dummy_ns->flavor = FLAV_MICRODESC;
+  dummy_ns->routerstatus_list = smartlist_new();
+
+  /* Setup an OR conn so we can pass it to the DoS subsystem. */
+  or_connection_t or_conn;
+  tor_addr_parse(&or_conn.real_addr, "42.42.42.42");
+
+  rs = tor_malloc_zero(sizeof(*rs));
+  rs->addr = tor_addr_to_ipv4h(&or_conn.real_addr);
+  crypto_rand(rs->identity_digest, sizeof(rs->identity_digest));
+  smartlist_add(dummy_ns->routerstatus_list, rs);
+
+  /* This will make the nodelist bloom filter very large
+   * (the_nodelist->node_addrs) so we will fail the contain test rarely. */
+  addr_per_node = 1024;
+  nodelist_set_consensus(dummy_ns);
+
+  /* We have now a node in our list so we'll make sure we don't count it as a
+   * client connection. */
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &or_conn.real_addr, NULL, 0);
+  /* Suppose we have 5 connections in rapid succession, the counter should
+   * always be 0 because we should ignore this. */
+  dos_new_client_conn(&or_conn);
+  dos_new_client_conn(&or_conn);
+  dos_new_client_conn(&or_conn);
+  dos_new_client_conn(&or_conn);
+  dos_new_client_conn(&or_conn);
+  entry = geoip_lookup_client(&or_conn.real_addr, NULL, GEOIP_CLIENT_CONNECT);
+  tt_assert(entry);
+  /* We should have a count of 0. */
+  tt_uint_op(entry->dos_stats.concurrent_count, OP_EQ, 0);
+
+  /* To make sure that his is working properly, make a unknown client
+   * connection and see if we do get it. */
+  tor_addr_parse(&or_conn.real_addr, "42.42.42.43");
+  geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &or_conn.real_addr, NULL, 0);
+  dos_new_client_conn(&or_conn);
+  dos_new_client_conn(&or_conn);
+  entry = geoip_lookup_client(&or_conn.real_addr, NULL, GEOIP_CLIENT_CONNECT);
+  tt_assert(entry);
+  /* We should have a count of 2. */
+  tt_uint_op(entry->dos_stats.concurrent_count, OP_EQ, 2);
+
+ done:
+  routerstatus_free(rs); routerinfo_free(ri); microdesc_free(md);
+  smartlist_clear(dummy_ns->routerstatus_list);
+  networkstatus_vote_free(dummy_ns);
+  dos_free_all();
+  UNMOCK(networkstatus_get_latest_consensus);
+  UNMOCK(networkstatus_get_latest_consensus_by_flavor);
+  UNMOCK(get_estimated_address_per_node);
+  UNMOCK(get_param_cc_enabled);
+}
+
+struct testcase_t dos_tests[] = {
+  { "conn_creation", test_dos_conn_creation, TT_FORK, NULL, NULL },
+  { "circuit_creation", test_dos_circuit_creation, TT_FORK, NULL, NULL },
+  { "bucket_refill", test_dos_bucket_refill, TT_FORK, NULL, NULL },
+  { "known_relay" , test_known_relay, TT_FORK,
+    NULL, NULL },
+  END_OF_TESTCASES
+};
+