/* Copyright (c) 2013-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */

#define TOR_CHANNEL_INTERNAL_
#define CHANNEL_PRIVATE_
#include "or.h"
#include "channel.h"
/* For channel_note_destroy_not_pending */
#include "circuitlist.h"
#include "circuitmux.h"
/* For var_cell_free */
#include "connection_or.h"
/* For packed_cell stuff */
#define RELAY_PRIVATE
#include "relay.h"
/* For init/free stuff */
#include "scheduler.h"

/* Test suite stuff */
#include "test.h"
#include "fakechans.h"

static int test_chan_accept_cells = 0;
static int test_chan_fixed_cells_recved = 0;
static cell_t * test_chan_last_seen_fixed_cell_ptr = NULL;
static int test_chan_var_cells_recved = 0;
static var_cell_t * test_chan_last_seen_var_cell_ptr = NULL;
static int test_cells_written = 0;
static int test_doesnt_want_writes_count = 0;
static int test_dumpstats_calls = 0;
static int test_has_waiting_cells_count = 0;
static double test_overhead_estimate = 1.0;
static int test_releases_count = 0;
static channel_t *dump_statistics_mock_target = NULL;
static int dump_statistics_mock_matches = 0;

static void chan_test_channel_dump_statistics_mock(
    channel_t *chan, int severity);
static void chan_test_cell_handler(channel_t *ch,
                                   cell_t *cell);
static const char * chan_test_describe_transport(channel_t *ch);
static void chan_test_dumpstats(channel_t *ch, int severity);
static void chan_test_var_cell_handler(channel_t *ch,
                                       var_cell_t *var_cell);
static void chan_test_close(channel_t *ch);
static void chan_test_error(channel_t *ch);
static void chan_test_finish_close(channel_t *ch);
static const char * chan_test_get_remote_descr(channel_t *ch, int flags);
static int chan_test_is_canonical(channel_t *ch, int req);
static size_t chan_test_num_bytes_queued(channel_t *ch);
static int chan_test_num_cells_writeable(channel_t *ch);
static int chan_test_write_cell(channel_t *ch, cell_t *cell);
static int chan_test_write_packed_cell(channel_t *ch,
                                       packed_cell_t *packed_cell);
static int chan_test_write_var_cell(channel_t *ch, var_cell_t *var_cell);
static void scheduler_channel_doesnt_want_writes_mock(channel_t *ch);

static void test_channel_dumpstats(void *arg);
static void test_channel_incoming(void *arg);
static void test_channel_lifecycle(void *arg);

static const char *
chan_test_describe_transport(channel_t *ch)
{
  tt_ptr_op(ch, OP_NE, NULL);

 done:
  return "Fake channel for unit tests";
}

/**
 * Mock for channel_dump_statistics(); if the channel matches the
 * target, bump a counter - otherwise ignore.
 */

static void
chan_test_channel_dump_statistics_mock(channel_t *chan, int severity)
{
  tt_ptr_op(chan, OP_NE, NULL);

  (void)severity;

  if (chan != NULL && chan == dump_statistics_mock_target) {
    ++dump_statistics_mock_matches;
  }

 done:
  return;
}

/*
 * Handle an incoming fixed-size cell for unit tests
 */

static void
chan_test_cell_handler(channel_t *ch,
                       cell_t *cell)
{
  tt_assert(ch);
  tt_assert(cell);

  test_chan_last_seen_fixed_cell_ptr = cell;
  ++test_chan_fixed_cells_recved;

 done:
  return;
}

/*
 * Fake transport-specific stats call
 */

static void
chan_test_dumpstats(channel_t *ch, int severity)
{
  tt_ptr_op(ch, OP_NE, NULL);

  (void)severity;

  ++test_dumpstats_calls;

 done:
  return;
}

/*
 * Handle an incoming variable-size cell for unit tests
 */

static void
chan_test_var_cell_handler(channel_t *ch,
                           var_cell_t *var_cell)
{
  tt_assert(ch);
  tt_assert(var_cell);

  test_chan_last_seen_var_cell_ptr = var_cell;
  ++test_chan_var_cells_recved;

 done:
  return;
}

static void
chan_test_close(channel_t *ch)
{
  tt_assert(ch);

 done:
  return;
}

/*
 * Close a channel through the error path
 */

static void
chan_test_error(channel_t *ch)
{
  tt_assert(ch);
  tt_assert(!(ch->state == CHANNEL_STATE_CLOSING ||
                ch->state == CHANNEL_STATE_ERROR ||
                ch->state == CHANNEL_STATE_CLOSED));

  channel_close_for_error(ch);

 done:
  return;
}

/*
 * Finish closing a channel from CHANNEL_STATE_CLOSING
 */

static void
chan_test_finish_close(channel_t *ch)
{
  tt_assert(ch);
  tt_assert(ch->state == CHANNEL_STATE_CLOSING);

  channel_closed(ch);

 done:
  return;
}

static const char *
chan_test_get_remote_descr(channel_t *ch, int flags)
{
  tt_assert(ch);
  tt_int_op(flags & ~(GRD_FLAG_ORIGINAL | GRD_FLAG_ADDR_ONLY), OP_EQ, 0);

 done:
  return "Fake channel for unit tests; no real endpoint";
}

static double
chan_test_get_overhead_estimate(channel_t *ch)
{
  tt_assert(ch);

 done:
  return test_overhead_estimate;
}

static int
chan_test_is_canonical(channel_t *ch, int req)
{
  tt_ptr_op(ch, OP_NE, NULL);
  tt_assert(req == 0 || req == 1);

 done:
  /* Fake channels are always canonical */
  return 1;
}

static size_t
chan_test_num_bytes_queued(channel_t *ch)
{
  tt_assert(ch);

 done:
  return 0;
}

static int
chan_test_num_cells_writeable(channel_t *ch)
{
  tt_assert(ch);

 done:
  return 32;
}

static int
chan_test_write_cell(channel_t *ch, cell_t *cell)
{
  int rv = 0;

  tt_assert(ch);
  tt_assert(cell);

  if (test_chan_accept_cells) {
    /* Free the cell and bump the counter */
    tor_free(cell);
    ++test_cells_written;
    rv = 1;
  }
  /* else return 0, we didn't accept it */

 done:
  return rv;
}

static int
chan_test_write_packed_cell(channel_t *ch,
                            packed_cell_t *packed_cell)
{
  int rv = 0;

  tt_assert(ch);
  tt_assert(packed_cell);

  if (test_chan_accept_cells) {
    /* Free the cell and bump the counter */
    packed_cell_free(packed_cell);
    ++test_cells_written;
    rv = 1;
  }
  /* else return 0, we didn't accept it */

 done:
  return rv;
}

static int
chan_test_write_var_cell(channel_t *ch, var_cell_t *var_cell)
{
  int rv = 0;

  tt_assert(ch);
  tt_assert(var_cell);

  if (test_chan_accept_cells) {
    /* Free the cell and bump the counter */
    var_cell_free(var_cell);
    ++test_cells_written;
    rv = 1;
  }
  /* else return 0, we didn't accept it */

 done:
  return rv;
}

/**
 * Fill out c with a new fake cell for test suite use
 */

void
make_fake_cell(cell_t *c)
{
  tt_ptr_op(c, OP_NE, NULL);

  c->circ_id = 1;
  c->command = CELL_RELAY;
  memset(c->payload, 0, CELL_PAYLOAD_SIZE);

 done:
  return;
}

/**
 * Fill out c with a new fake var_cell for test suite use
 */

void
make_fake_var_cell(var_cell_t *c)
{
  tt_ptr_op(c, OP_NE, NULL);

  c->circ_id = 1;
  c->command = CELL_VERSIONS;
  c->payload_len = CELL_PAYLOAD_SIZE / 2;
  memset(c->payload, 0, c->payload_len);

 done:
  return;
}

/**
 * Set up a new fake channel for the test suite
 */

channel_t *
new_fake_channel(void)
{
  channel_t *chan = tor_malloc_zero(sizeof(channel_t));
  channel_init(chan);

  chan->close = chan_test_close;
  chan->get_overhead_estimate = chan_test_get_overhead_estimate;
  chan->get_remote_descr = chan_test_get_remote_descr;
  chan->num_bytes_queued = chan_test_num_bytes_queued;
  chan->num_cells_writeable = chan_test_num_cells_writeable;
  chan->write_cell = chan_test_write_cell;
  chan->write_packed_cell = chan_test_write_packed_cell;
  chan->write_var_cell = chan_test_write_var_cell;
  chan->state = CHANNEL_STATE_OPEN;

  return chan;
}

void
free_fake_channel(channel_t *chan)
{
  if (! chan)
    return;

  if (chan->cmux)
    circuitmux_free(chan->cmux);

  tor_free(chan);
}

/**
 * Counter query for scheduler_channel_has_waiting_cells_mock()
 */

int
get_mock_scheduler_has_waiting_cells_count(void)
{
  return test_has_waiting_cells_count;
}

/**
 * Mock for scheduler_channel_has_waiting_cells()
 */

void
scheduler_channel_has_waiting_cells_mock(channel_t *ch)
{
  (void)ch;

  /* Increment counter */
  ++test_has_waiting_cells_count;

  return;
}

static void
scheduler_channel_doesnt_want_writes_mock(channel_t *ch)
{
  (void)ch;

  /* Increment counter */
  ++test_doesnt_want_writes_count;

  return;
}

/**
 * Counter query for scheduler_release_channel_mock()
 */

int
get_mock_scheduler_release_channel_count(void)
{
  return test_releases_count;
}

/**
 * Mock for scheduler_release_channel()
 */

void
scheduler_release_channel_mock(channel_t *ch)
{
  (void)ch;

  /* Increment counter */
  ++test_releases_count;

  return;
}

/**
 * Test for channel_dumpstats() and limited test for
 * channel_dump_statistics()
 */

static void
test_channel_dumpstats(void *arg)
{
  channel_t *ch = NULL;
  packed_cell_t *p_cell = NULL;
  int old_count;

  (void)arg;

  /* Mock these for duration of the test */
  MOCK(scheduler_channel_doesnt_want_writes,
       scheduler_channel_doesnt_want_writes_mock);
  MOCK(scheduler_release_channel,
       scheduler_release_channel_mock);

  /* Set up a new fake channel */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->cmux = circuitmux_alloc();

  /* Try to register it */
  channel_register(ch);
  tt_assert(ch->registered);

  /* Set up mock */
  dump_statistics_mock_target = ch;
  dump_statistics_mock_matches = 0;
  MOCK(channel_dump_statistics,
       chan_test_channel_dump_statistics_mock);

  /* Call channel_dumpstats() */
  channel_dumpstats(LOG_DEBUG);

  /* Assert that we hit the mock */
  tt_int_op(dump_statistics_mock_matches, OP_EQ, 1);

  /* Close the channel */
  channel_mark_for_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);

  /* Try again and hit the finished channel */
  channel_dumpstats(LOG_DEBUG);
  tt_int_op(dump_statistics_mock_matches, OP_EQ, 2);

  channel_run_cleanup();
  ch = NULL;

  /* Now we should hit nothing */
  channel_dumpstats(LOG_DEBUG);
  tt_int_op(dump_statistics_mock_matches, OP_EQ, 2);

  /* Unmock */
  UNMOCK(channel_dump_statistics);
  dump_statistics_mock_target = NULL;
  dump_statistics_mock_matches = 0;

  /* Now make another channel */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->cmux = circuitmux_alloc();
  channel_register(ch);
  tt_assert(ch->registered);
  /* Lie about its age so dumpstats gets coverage for rate calculations */
  ch->timestamp_created = time(NULL) - 30;
  tt_assert(ch->timestamp_created > 0);
  tt_assert(time(NULL) > ch->timestamp_created);

  /* Put cells through it both ways to make the counters non-zero */
  p_cell = packed_cell_new();
  test_chan_accept_cells = 1;
  old_count = test_cells_written;
  channel_write_packed_cell(ch, p_cell);
  tt_int_op(test_cells_written, OP_EQ, old_count + 1);
  tt_assert(ch->n_bytes_xmitted > 0);
  tt_assert(ch->n_cells_xmitted > 0);

  /* Receive path */
  channel_set_cell_handlers(ch,
                            chan_test_cell_handler,
                            chan_test_var_cell_handler);
  tt_ptr_op(channel_get_cell_handler(ch), OP_EQ, chan_test_cell_handler);
  tt_ptr_op(channel_get_var_cell_handler(ch), OP_EQ,
            chan_test_var_cell_handler);
  p_cell = packed_cell_new();
  old_count = test_chan_fixed_cells_recved;
  tt_int_op(test_chan_fixed_cells_recved, OP_EQ, old_count + 1);
  tt_assert(ch->n_bytes_recved > 0);
  tt_assert(ch->n_cells_recved > 0);

  /* Test channel_dump_statistics */
  ch->describe_transport = chan_test_describe_transport;
  ch->dumpstats = chan_test_dumpstats;
  ch->is_canonical = chan_test_is_canonical;
  old_count = test_dumpstats_calls;
  channel_dump_statistics(ch, LOG_DEBUG);
  tt_int_op(test_dumpstats_calls, OP_EQ, old_count + 1);

  /* Close the channel */
  channel_mark_for_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);
  channel_run_cleanup();
  ch = NULL;

 done:
  free_fake_channel(ch);

  UNMOCK(scheduler_channel_doesnt_want_writes);
  UNMOCK(scheduler_release_channel);

  return;
}

static void
test_channel_incoming(void *arg)
{
  channel_t *ch = NULL;
  cell_t *cell = NULL;
  var_cell_t *var_cell = NULL;
  int old_count;

  (void)arg;

  /* Mock these for duration of the test */
  MOCK(scheduler_channel_doesnt_want_writes,
       scheduler_channel_doesnt_want_writes_mock);
  MOCK(scheduler_release_channel,
       scheduler_release_channel_mock);

  /* Accept cells to lower layer */
  test_chan_accept_cells = 1;
  /* Use default overhead factor */
  test_overhead_estimate = 1.0;

  ch = new_fake_channel();
  tt_assert(ch);
  /* Start it off in OPENING */
  ch->state = CHANNEL_STATE_OPENING;
  /* We'll need a cmux */
  ch->cmux = circuitmux_alloc();

  /* Install incoming cell handlers */
  channel_set_cell_handlers(ch,
                            chan_test_cell_handler,
                            chan_test_var_cell_handler);
  /* Test cell handler getters */
  tt_ptr_op(channel_get_cell_handler(ch), OP_EQ, chan_test_cell_handler);
  tt_ptr_op(channel_get_var_cell_handler(ch), OP_EQ,
            chan_test_var_cell_handler);

  /* Try to register it */
  channel_register(ch);
  tt_assert(ch->registered);

  /* Open it */
  channel_change_state_open(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_OPEN);

  /* Receive a fixed cell */
  cell = tor_malloc_zero(sizeof(cell_t));
  make_fake_cell(cell);
  old_count = test_chan_fixed_cells_recved;
  tor_free(cell);
  tt_int_op(test_chan_fixed_cells_recved, OP_EQ, old_count + 1);

  /* Receive a variable-size cell */
  var_cell = tor_malloc_zero(sizeof(var_cell_t) + CELL_PAYLOAD_SIZE);
  make_fake_var_cell(var_cell);
  old_count = test_chan_var_cells_recved;
  tor_free(cell);
  tt_int_op(test_chan_var_cells_recved, OP_EQ, old_count + 1);

  /* Close it */
  channel_mark_for_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);
  channel_run_cleanup();
  ch = NULL;

 done:
  free_fake_channel(ch);
  tor_free(cell);
  tor_free(var_cell);

  UNMOCK(scheduler_channel_doesnt_want_writes);
  UNMOCK(scheduler_release_channel);

  return;
}

/**
 * Normal channel lifecycle test:
 *
 * OPENING->OPEN->MAINT->OPEN->CLOSING->CLOSED
 */

static void
test_channel_lifecycle(void *arg)
{
  channel_t *ch1 = NULL, *ch2 = NULL;
  packed_cell_t *p_cell = NULL;
  int old_count, init_doesnt_want_writes_count;
  int init_releases_count;

  (void)arg;

  /* Mock these for the whole lifecycle test */
  MOCK(scheduler_channel_doesnt_want_writes,
       scheduler_channel_doesnt_want_writes_mock);
  MOCK(scheduler_release_channel,
       scheduler_release_channel_mock);

  /* Cache some initial counter values */
  init_doesnt_want_writes_count = test_doesnt_want_writes_count;
  init_releases_count = test_releases_count;

  /* Accept cells to lower layer */
  test_chan_accept_cells = 1;
  /* Use default overhead factor */
  test_overhead_estimate = 1.0;

  ch1 = new_fake_channel();
  tt_assert(ch1);
  /* Start it off in OPENING */
  ch1->state = CHANNEL_STATE_OPENING;
  /* We'll need a cmux */
  ch1->cmux = circuitmux_alloc();

  /* Try to register it */
  channel_register(ch1);
  tt_assert(ch1->registered);

  /* Try to write a cell through (should queue) */
  p_cell = packed_cell_new();
  old_count = test_cells_written;
  channel_write_packed_cell(ch1, p_cell);
  tt_int_op(old_count, OP_EQ, test_cells_written);

  /* Move it to OPEN and flush */
  channel_change_state_open(ch1);

  /* Queue should drain */
  tt_int_op(old_count + 1, OP_EQ, test_cells_written);

  /* Get another one */
  ch2 = new_fake_channel();
  tt_assert(ch2);
  ch2->state = CHANNEL_STATE_OPENING;
  ch2->cmux = circuitmux_alloc();

  /* Register */
  channel_register(ch2);
  tt_assert(ch2->registered);

  /* Check counters */
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count);
  tt_int_op(test_releases_count, OP_EQ, init_releases_count);

  /* Move ch1 to MAINT */
  channel_change_state(ch1, CHANNEL_STATE_MAINT);
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count + 1);
  tt_int_op(test_releases_count, OP_EQ, init_releases_count);

  /* Move ch2 to OPEN */
  channel_change_state_open(ch2);
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count + 1);
  tt_int_op(test_releases_count, OP_EQ, init_releases_count);

  /* Move ch1 back to OPEN */
  channel_change_state_open(ch1);
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count + 1);
  tt_int_op(test_releases_count, OP_EQ, init_releases_count);

  /* Mark ch2 for close */
  channel_mark_for_close(ch2);
  tt_int_op(ch2->state, OP_EQ, CHANNEL_STATE_CLOSING);
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count + 1);
  tt_int_op(test_releases_count, OP_EQ, init_releases_count + 1);

  /* Shut down channels */
  channel_free_all();
  ch1 = ch2 = NULL;
  tt_int_op(test_doesnt_want_writes_count, OP_EQ,
            init_doesnt_want_writes_count + 1);
  /* channel_free() calls scheduler_release_channel() */
  tt_int_op(test_releases_count, OP_EQ, init_releases_count + 4);

 done:
  free_fake_channel(ch1);
  free_fake_channel(ch2);

  UNMOCK(scheduler_channel_doesnt_want_writes);
  UNMOCK(scheduler_release_channel);

  return;
}

/**
 * Weird channel lifecycle test:
 *
 * OPENING->CLOSING->CLOSED
 * OPENING->OPEN->CLOSING->ERROR
 * OPENING->OPEN->MAINT->CLOSING->CLOSED
 * OPENING->OPEN->MAINT->CLOSING->ERROR
 */

static void
test_channel_lifecycle_2(void *arg)
{
  channel_t *ch = NULL;

  (void)arg;

  /* Mock these for the whole lifecycle test */
  MOCK(scheduler_channel_doesnt_want_writes,
       scheduler_channel_doesnt_want_writes_mock);
  MOCK(scheduler_release_channel,
       scheduler_release_channel_mock);

  /* Accept cells to lower layer */
  test_chan_accept_cells = 1;
  /* Use default overhead factor */
  test_overhead_estimate = 1.0;

  ch = new_fake_channel();
  tt_assert(ch);
  /* Start it off in OPENING */
  ch->state = CHANNEL_STATE_OPENING;
  /* The full lifecycle test needs a cmux */
  ch->cmux = circuitmux_alloc();

  /* Try to register it */
  channel_register(ch);
  tt_assert(ch->registered);

  /* Try to close it */
  channel_mark_for_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);

  /* Finish closing it */
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);
  channel_run_cleanup();
  ch = NULL;

  /* Now try OPENING->OPEN->CLOSING->ERROR */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->state = CHANNEL_STATE_OPENING;
  ch->cmux = circuitmux_alloc();
  channel_register(ch);
  tt_assert(ch->registered);

  /* Finish opening it */
  channel_change_state_open(ch);

  /* Error exit from lower layer */
  chan_test_error(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_ERROR);
  channel_run_cleanup();
  ch = NULL;

  /* OPENING->OPEN->MAINT->CLOSING->CLOSED close from maintenance state */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->state = CHANNEL_STATE_OPENING;
  ch->cmux = circuitmux_alloc();
  channel_register(ch);
  tt_assert(ch->registered);

  /* Finish opening it */
  channel_change_state_open(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_OPEN);

  /* Go to maintenance state */
  channel_change_state(ch, CHANNEL_STATE_MAINT);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_MAINT);

  /* Lower layer close */
  channel_mark_for_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);

  /* Finish */
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);
  channel_run_cleanup();
  ch = NULL;

  /*
   * OPENING->OPEN->MAINT->CLOSING->CLOSED lower-layer close during
   * maintenance state
   */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->state = CHANNEL_STATE_OPENING;
  ch->cmux = circuitmux_alloc();
  channel_register(ch);
  tt_assert(ch->registered);

  /* Finish opening it */
  channel_change_state_open(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_OPEN);

  /* Go to maintenance state */
  channel_change_state(ch, CHANNEL_STATE_MAINT);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_MAINT);

  /* Lower layer close */
  channel_close_from_lower_layer(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);

  /* Finish */
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSED);
  channel_run_cleanup();
  ch = NULL;

  /* OPENING->OPEN->MAINT->CLOSING->ERROR */
  ch = new_fake_channel();
  tt_assert(ch);
  ch->state = CHANNEL_STATE_OPENING;
  ch->cmux = circuitmux_alloc();
  channel_register(ch);
  tt_assert(ch->registered);

  /* Finish opening it */
  channel_change_state_open(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_OPEN);

  /* Go to maintenance state */
  channel_change_state(ch, CHANNEL_STATE_MAINT);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_MAINT);

  /* Lower layer close */
  chan_test_error(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_CLOSING);

  /* Finish */
  chan_test_finish_close(ch);
  tt_int_op(ch->state, OP_EQ, CHANNEL_STATE_ERROR);
  channel_run_cleanup();
  ch = NULL;

  /* Shut down channels */
  channel_free_all();

 done:
  tor_free(ch);

  UNMOCK(scheduler_channel_doesnt_want_writes);
  UNMOCK(scheduler_release_channel);

  return;
}

static void
test_channel_id_map(void *arg)
{
  (void)arg;
#define N_CHAN 6
  char rsa_id[N_CHAN][DIGEST_LEN];
  ed25519_public_key_t *ed_id[N_CHAN];
  channel_t *chan[N_CHAN];
  int i;
  ed25519_public_key_t ed_zero;
  memset(&ed_zero, 0, sizeof(ed_zero));

  tt_int_op(DIGEST_LEN, OP_EQ, sizeof(rsa_id[0])); // Do I remember C?

  for (i = 0; i < N_CHAN; ++i) {
    crypto_rand(rsa_id[i], DIGEST_LEN);
    ed_id[i] = tor_malloc_zero(sizeof(*ed_id[i]));
    crypto_rand((char*)ed_id[i]->pubkey, sizeof(ed_id[i]->pubkey));
  }

  /* For channel 3, have no Ed identity. */
  tor_free(ed_id[3]);

  /* Channel 2 and 4 have same ROSA identity */
  memcpy(rsa_id[4], rsa_id[2], DIGEST_LEN);

  /* Channel 2 and 4 and 5 have same RSA identity */
  memcpy(rsa_id[4], rsa_id[2], DIGEST_LEN);
  memcpy(rsa_id[5], rsa_id[2], DIGEST_LEN);

  /* Channels 2 and 5 have same Ed25519 identity */
  memcpy(ed_id[5], ed_id[2], sizeof(*ed_id[2]));

  for (i = 0; i < N_CHAN; ++i) {
    chan[i] = new_fake_channel();
    channel_register(chan[i]);
    channel_set_identity_digest(chan[i], rsa_id[i], ed_id[i]);
  }

  /* Lookup by RSA id only */
  tt_ptr_op(chan[0], OP_EQ,
            channel_find_by_remote_identity(rsa_id[0], NULL));
  tt_ptr_op(chan[1], OP_EQ,
            channel_find_by_remote_identity(rsa_id[1], NULL));
  tt_ptr_op(chan[3], OP_EQ,
            channel_find_by_remote_identity(rsa_id[3], NULL));
  channel_t *ch;
  ch = channel_find_by_remote_identity(rsa_id[2], NULL);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_ptr_op(ch, OP_EQ, NULL);

  /* As above, but with zero Ed25519 ID (meaning "any ID") */
  tt_ptr_op(chan[0], OP_EQ,
            channel_find_by_remote_identity(rsa_id[0], &ed_zero));
  tt_ptr_op(chan[1], OP_EQ,
            channel_find_by_remote_identity(rsa_id[1], &ed_zero));
  tt_ptr_op(chan[3], OP_EQ,
            channel_find_by_remote_identity(rsa_id[3], &ed_zero));
  ch = channel_find_by_remote_identity(rsa_id[2], &ed_zero);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_assert(ch == chan[2] || ch == chan[4] || ch == chan[5]);
  ch = channel_next_with_rsa_identity(ch);
  tt_ptr_op(ch, OP_EQ, NULL);

  /* Lookup nonexistent RSA identity */
  tt_ptr_op(NULL, OP_EQ,
            channel_find_by_remote_identity("!!!!!!!!!!!!!!!!!!!!", NULL));

  /* Look up by full identity pair */
  tt_ptr_op(chan[0], OP_EQ,
            channel_find_by_remote_identity(rsa_id[0], ed_id[0]));
  tt_ptr_op(chan[1], OP_EQ,
            channel_find_by_remote_identity(rsa_id[1], ed_id[1]));
  tt_ptr_op(chan[3], OP_EQ,
            channel_find_by_remote_identity(rsa_id[3], ed_id[3] /*NULL*/));
  tt_ptr_op(chan[4], OP_EQ,
            channel_find_by_remote_identity(rsa_id[4], ed_id[4]));
  ch = channel_find_by_remote_identity(rsa_id[2], ed_id[2]);
  tt_assert(ch == chan[2] || ch == chan[5]);

  /* Look up RSA identity with wrong ed25519 identity */
  tt_ptr_op(NULL, OP_EQ,
            channel_find_by_remote_identity(rsa_id[4], ed_id[0]));
  tt_ptr_op(NULL, OP_EQ,
            channel_find_by_remote_identity(rsa_id[2], ed_id[1]));
  tt_ptr_op(NULL, OP_EQ,
            channel_find_by_remote_identity(rsa_id[3], ed_id[1]));

 done:
  for (i = 0; i < N_CHAN; ++i) {
    channel_clear_identity_digest(chan[i]);
    channel_unregister(chan[i]);
    free_fake_channel(chan[i]);
    tor_free(ed_id[i]);
  }
#undef N_CHAN
}

struct testcase_t channel_tests[] = {
  { "dumpstats", test_channel_dumpstats, TT_FORK, NULL, NULL },
  { "incoming", test_channel_incoming, TT_FORK, NULL, NULL },
  { "lifecycle", test_channel_lifecycle, TT_FORK, NULL, NULL },
  { "lifecycle_2", test_channel_lifecycle_2, TT_FORK, NULL, NULL },
  { "id_map", test_channel_id_map, TT_FORK, NULL, NULL },
  END_OF_TESTCASES
};