shared_random_state.c 40 KB
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/* Copyright (c) 2016-2020, The Tor Project, Inc. */
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/* See LICENSE for licensing information */

/**
 * \file shared_random_state.c
 *
 * \brief Functions and data structures for the state of the random protocol
 *        as defined in proposal #250.
 **/

#define SHARED_RANDOM_STATE_PRIVATE

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#include "core/or/or.h"
#include "app/config/config.h"
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#include "lib/confmgt/confmgt.h"
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#include "lib/crypt_ops/crypto_util.h"
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#include "feature/dirauth/dirvote.h"
#include "feature/nodelist/networkstatus.h"
#include "feature/relay/router.h"
#include "feature/dirauth/shared_random.h"
#include "feature/hs_common/shared_random_client.h"
#include "feature/dirauth/shared_random_state.h"
#include "feature/dircommon/voting_schedule.h"
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#include "lib/encoding/confline.h"
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#include "lib/version/torversion.h"
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#include "app/config/or_state_st.h"
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/** Default filename of the shared random state on disk. */
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static const char default_fname[] = "sr-state";

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/** String representation of a protocol phase. */
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static const char *phase_str[] = { "unknown", "commit", "reveal" };

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/** Our shared random protocol state. There is only one possible state per
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 * protocol run so this is the global state which is reset at every run once
 * the shared random value has been computed. */
static sr_state_t *sr_state = NULL;

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/** Representation of our persistent state on disk. The sr_state above
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 * contains the data parsed from this state. When we save to disk, we
 * translate the sr_state to this sr_disk_state. */
static sr_disk_state_t *sr_disk_state = NULL;

/* Disk state file keys. */
static const char dstate_commit_key[] = "Commit";
static const char dstate_prev_srv_key[] = "SharedRandPreviousValue";
static const char dstate_cur_srv_key[] = "SharedRandCurrentValue";

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/** dummy instance of sr_disk_state_t, used for type-checking its
 * members with CONF_CHECK_VAR_TYPE. */
DUMMY_TYPECHECK_INSTANCE(sr_disk_state_t);

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#define VAR(varname,conftype,member,initvalue)                          \
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  CONFIG_VAR_ETYPE(sr_disk_state_t, varname, conftype, member, 0, initvalue)
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#define V(member,conftype,initvalue)            \
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  VAR(#member, conftype, member, initvalue)
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/** Our persistent state magic number. */
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#define SR_DISK_STATE_MAGIC 0x98AB1254

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/** Array of variables that are saved to disk as a persistent state. */
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static const config_var_t state_vars[] = {
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  V(Version,                    POSINT, "0"),
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  V(TorVersion,                 STRING, NULL),
  V(ValidAfter,                 ISOTIME, NULL),
  V(ValidUntil,                 ISOTIME, NULL),

  V(Commit,                     LINELIST, NULL),

  V(SharedRandValues,           LINELIST_V, NULL),
  VAR("SharedRandPreviousValue",LINELIST_S, SharedRandValues, NULL),
  VAR("SharedRandCurrentValue", LINELIST_S, SharedRandValues, NULL),
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  END_OF_CONFIG_VARS
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};

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/** "Extra" variable in the state that receives lines we can't parse. This
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 * lets us preserve options from versions of Tor newer than us. */
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static const struct_member_t state_extra_var = {
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  .name = "__extra",
  .type = CONFIG_TYPE_LINELIST,
  .offset = offsetof(sr_disk_state_t, ExtraLines),
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};

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/** Configuration format of sr_disk_state_t. */
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static const config_format_t state_format = {
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  .size = sizeof(sr_disk_state_t),
  .magic = {
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   "sr_disk_state_t",
   SR_DISK_STATE_MAGIC,
   offsetof(sr_disk_state_t, magic_),
  },
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  .vars = state_vars,
  .extra = &state_extra_var,
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};

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/** Global configuration manager for the shared-random state file */
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static config_mgr_t *shared_random_state_mgr = NULL;

/** Return the configuration manager for the shared-random state file. */
static const config_mgr_t *
get_srs_mgr(void)
{
  if (PREDICT_UNLIKELY(shared_random_state_mgr == NULL)) {
    shared_random_state_mgr = config_mgr_new(&state_format);
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    config_mgr_freeze(shared_random_state_mgr);
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  }
  return shared_random_state_mgr;
}

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static void state_query_del_(sr_state_object_t obj_type, void *data);

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/** Return a string representation of a protocol phase. */
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STATIC const char *
get_phase_str(sr_phase_t phase)
{
  const char *the_string = NULL;

  switch (phase) {
  case SR_PHASE_COMMIT:
  case SR_PHASE_REVEAL:
    the_string = phase_str[phase];
    break;
  default:
    /* Unknown phase shouldn't be possible. */
    tor_assert(0);
  }

  return the_string;
}
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/** Return the time we should expire the state file created at <b>now</b>.
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 * We expire the state file in the beginning of the next protocol run. */
STATIC time_t
get_state_valid_until_time(time_t now)
{
  int total_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
  int current_round, voting_interval, rounds_left;
  time_t valid_until, beginning_of_current_round;

  voting_interval = get_voting_interval();
  /* Find the time the current round started. */
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  beginning_of_current_round = get_start_time_of_current_round();
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  /* Find how many rounds are left till the end of the protocol run */
  current_round = (now / voting_interval) % total_rounds;
  rounds_left = total_rounds - current_round;

  /* To find the valid-until time now, take the start time of the current
   * round and add to it the time it takes for the leftover rounds to
   * complete. */
  valid_until = beginning_of_current_round + (rounds_left * voting_interval);

  { /* Logging */
    char tbuf[ISO_TIME_LEN + 1];
    format_iso_time(tbuf, valid_until);
    log_debug(LD_DIR, "SR: Valid until time for state set to %s.", tbuf);
  }

  return valid_until;
}

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/** Given the consensus 'valid-after' time, return the protocol phase we should
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 * be in. */
STATIC sr_phase_t
get_sr_protocol_phase(time_t valid_after)
{
  /* Shared random protocol has two phases, commit and reveal. */
  int total_periods = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
  int current_slot;

  /* Split time into slots of size 'voting_interval'. See which slot we are
   * currently into, and find which phase it corresponds to. */
  current_slot = (valid_after / get_voting_interval()) % total_periods;

  if (current_slot < SHARED_RANDOM_N_ROUNDS) {
    return SR_PHASE_COMMIT;
  } else {
    return SR_PHASE_REVEAL;
  }
}

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/** Add the given <b>commit</b> to <b>state</b>. It MUST be a valid commit
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 * and there shouldn't be a commit from the same authority in the state
 * already else verification hasn't been done prior. This takes ownership of
 * the commit once in our state. */
static void
commit_add_to_state(sr_commit_t *commit, sr_state_t *state)
{
  sr_commit_t *saved_commit;

  tor_assert(commit);
  tor_assert(state);

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  saved_commit = digestmap_set(state->commits, commit->rsa_identity,
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                               commit);
  if (saved_commit != NULL) {
    /* This means we already have that commit in our state so adding twice
     * the same commit is either a code flow error, a corrupted disk state
     * or some new unknown issue. */
    log_warn(LD_DIR, "SR: Commit from %s exists in our state while "
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                     "adding it: '%s'", sr_commit_get_rsa_fpr(commit),
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                     commit->encoded_commit);
    sr_commit_free(saved_commit);
  }
}

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/** Helper: deallocate a commit object. (Used with digestmap_free(), which
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 * requires a function pointer whose argument is void *). */
static void
commit_free_(void *p)
{
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  sr_commit_free_(p);
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}

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#define state_free(val) \
  FREE_AND_NULL(sr_state_t, state_free_, (val))

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/** Free a state that was allocated with state_new(). */
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static void
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state_free_(sr_state_t *state)
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{
  if (state == NULL) {
    return;
  }
  tor_free(state->fname);
  digestmap_free(state->commits, commit_free_);
  tor_free(state->current_srv);
  tor_free(state->previous_srv);
  tor_free(state);
}

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/** Allocate an sr_state_t object and returns it. If no <b>fname</b>, the
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 * default file name is used. This function does NOT initialize the state
 * timestamp, phase or shared random value. NULL is never returned. */
static sr_state_t *
state_new(const char *fname, time_t now)
{
  sr_state_t *new_state = tor_malloc_zero(sizeof(*new_state));
  /* If file name is not provided, use default. */
  if (fname == NULL) {
    fname = default_fname;
  }
  new_state->fname = tor_strdup(fname);
  new_state->version = SR_PROTO_VERSION;
  new_state->commits = digestmap_new();
  new_state->phase = get_sr_protocol_phase(now);
  new_state->valid_until = get_state_valid_until_time(now);
  return new_state;
}

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/** Set our global state pointer with the one given. */
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static void
state_set(sr_state_t *state)
{
  tor_assert(state);
  if (sr_state != NULL) {
    state_free(sr_state);
  }
  sr_state = state;
}

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#define disk_state_free(val) \
  FREE_AND_NULL(sr_disk_state_t, disk_state_free_, (val))

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/** Free an allocated disk state. */
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static void
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disk_state_free_(sr_disk_state_t *state)
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{
  if (state == NULL) {
    return;
  }
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  config_free(get_srs_mgr(), state);
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}

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/** Allocate a new disk state, initialize it and return it. */
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static sr_disk_state_t *
disk_state_new(time_t now)
{
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  sr_disk_state_t *new_state = config_new(get_srs_mgr());
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  new_state->Version = SR_PROTO_VERSION;
  new_state->TorVersion = tor_strdup(get_version());
  new_state->ValidUntil = get_state_valid_until_time(now);
  new_state->ValidAfter = now;

  /* Init config format. */
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  config_init(get_srs_mgr(), new_state);
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  return new_state;
}

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/** Set our global disk state with the given state. */
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static void
disk_state_set(sr_disk_state_t *state)
{
  tor_assert(state);
  if (sr_disk_state != NULL) {
    disk_state_free(sr_disk_state);
  }
  sr_disk_state = state;
}

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/** Return -1 if the disk state is invalid (something in there that we can't or
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 * shouldn't use). Return 0 if everything checks out. */
static int
disk_state_validate(const sr_disk_state_t *state)
{
  time_t now;

  tor_assert(state);

  /* Do we support the protocol version in the state or is it 0 meaning
   * Version wasn't found in the state file or bad anyway ? */
  if (state->Version == 0 || state->Version > SR_PROTO_VERSION) {
    goto invalid;
  }

  /* If the valid until time is before now, we shouldn't use that state. */
  now = time(NULL);
  if (state->ValidUntil < now) {
    log_info(LD_DIR, "SR: Disk state has expired. Ignoring it.");
    goto invalid;
  }

  /* Make sure we don't have a valid after time that is earlier than a valid
   * until time which would make things not work well. */
  if (state->ValidAfter >= state->ValidUntil) {
    log_info(LD_DIR, "SR: Disk state valid after/until times are invalid.");
    goto invalid;
  }

  return 0;

 invalid:
  return -1;
}

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/** Parse the Commit line(s) in the disk state and translate them to the
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 * the memory state. Return 0 on success else -1 on error. */
static int
disk_state_parse_commits(sr_state_t *state,
                         const sr_disk_state_t *disk_state)
{
  config_line_t *line;
  smartlist_t *args = NULL;

  tor_assert(state);
  tor_assert(disk_state);

  for (line = disk_state->Commit; line; line = line->next) {
    sr_commit_t *commit = NULL;

    /* Extra safety. */
    if (strcasecmp(line->key, dstate_commit_key) ||
        line->value == NULL) {
      /* Ignore any lines that are not commits. */
      tor_fragile_assert();
      continue;
    }
    args = smartlist_new();
    smartlist_split_string(args, line->value, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args) < 3) {
      log_warn(LD_BUG, "SR: Too few arguments in Commit Line: %s",
               escaped(line->value));
      goto error;
    }
    commit = sr_parse_commit(args);
    if (commit == NULL) {
      /* Ignore badly formed commit. It could also be a authority
       * fingerprint that we don't know about so it shouldn't be used. */
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      smartlist_free(args);
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      continue;
    }
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    /* We consider parseable commit from our disk state to be valid because
     * they need to be in the first place to get in there. */
    commit->valid = 1;
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    /* Add commit to our state pointer. */
    commit_add_to_state(commit, state);

    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
  }

  return 0;

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  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
  smartlist_free(args);
  return -1;
}

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/** Parse a share random value line from the disk state and save it to dst
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 * which is an allocated srv object. Return 0 on success else -1. */
static int
disk_state_parse_srv(const char *value, sr_srv_t *dst)
{
  int ret = -1;
  smartlist_t *args;
  sr_srv_t *srv;

  tor_assert(value);
  tor_assert(dst);

  args = smartlist_new();
  smartlist_split_string(args, value, " ",
                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  if (smartlist_len(args) < 2) {
    log_warn(LD_BUG, "SR: Too few arguments in shared random value. "
             "Line: %s", escaped(value));
    goto error;
  }
  srv = sr_parse_srv(args);
  if (srv == NULL) {
    goto error;
  }
  dst->num_reveals = srv->num_reveals;
  memcpy(dst->value, srv->value, sizeof(dst->value));
  tor_free(srv);
  ret = 0;

 error:
  SMARTLIST_FOREACH(args, char *, s, tor_free(s));
  smartlist_free(args);
  return ret;
}

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/** Parse both SharedRandCurrentValue and SharedRandPreviousValue line from
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 * the state. Return 0 on success else -1. */
static int
disk_state_parse_sr_values(sr_state_t *state,
                           const sr_disk_state_t *disk_state)
{
  /* Only one value per type (current or previous) is allowed so we keep
   * track of it with these flag. */
  unsigned int seen_previous = 0, seen_current = 0;
  config_line_t *line;
  sr_srv_t *srv = NULL;

  tor_assert(state);
  tor_assert(disk_state);

  for (line = disk_state->SharedRandValues; line; line = line->next) {
    if (line->value == NULL) {
      continue;
    }
    srv = tor_malloc_zero(sizeof(*srv));
    if (disk_state_parse_srv(line->value, srv) < 0) {
      log_warn(LD_BUG, "SR: Broken current SRV line in state %s",
               escaped(line->value));
      goto bad;
    }
    if (!strcasecmp(line->key, dstate_prev_srv_key)) {
      if (seen_previous) {
        log_warn(LD_DIR, "SR: Second previous SRV value seen. Bad state");
        goto bad;
      }
      state->previous_srv = srv;
      seen_previous = 1;
    } else if (!strcasecmp(line->key, dstate_cur_srv_key)) {
      if (seen_current) {
        log_warn(LD_DIR, "SR: Second current SRV value seen. Bad state");
        goto bad;
      }
      state->current_srv = srv;
      seen_current = 1;
    } else {
      /* Unknown key. Ignoring. */
      tor_free(srv);
    }
  }

  return 0;
 bad:
  tor_free(srv);
  return -1;
}

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/** Parse the given disk state and set a newly allocated state. On success,
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 * return that state else NULL. */
static sr_state_t *
disk_state_parse(const sr_disk_state_t *new_disk_state)
{
  sr_state_t *new_state = state_new(default_fname, time(NULL));

  tor_assert(new_disk_state);

  new_state->version = new_disk_state->Version;
  new_state->valid_until = new_disk_state->ValidUntil;
  new_state->valid_after = new_disk_state->ValidAfter;

  /* Set our current phase according to the valid-after time in our disk
   * state. The disk state we are parsing contains everything for the phase
   * starting at valid_after so make sure our phase reflects that. */
  new_state->phase = get_sr_protocol_phase(new_state->valid_after);

  /* Parse the shared random values. */
  if (disk_state_parse_sr_values(new_state, new_disk_state) < 0) {
    goto error;
  }
  /* Parse the commits. */
  if (disk_state_parse_commits(new_state, new_disk_state) < 0) {
    goto error;
  }
  /* Great! This new state contains everything we had on disk. */
  return new_state;

 error:
  state_free(new_state);
  return NULL;
}

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/** From a valid commit object and an allocated config line, set the line's
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 * value to the state string representation of a commit. */
static void
disk_state_put_commit_line(const sr_commit_t *commit, config_line_t *line)
{
  char *reveal_str = NULL;

  tor_assert(commit);
  tor_assert(line);

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  if (!fast_mem_is_zero(commit->encoded_reveal,
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                       sizeof(commit->encoded_reveal))) {
    /* Add extra whitespace so we can format the line correctly. */
    tor_asprintf(&reveal_str, " %s", commit->encoded_reveal);
  }
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  tor_asprintf(&line->value, "%u %s %s %s%s",
               SR_PROTO_VERSION,
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               crypto_digest_algorithm_get_name(commit->alg),
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               sr_commit_get_rsa_fpr(commit),
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               commit->encoded_commit,
               reveal_str != NULL ? reveal_str : "");
  if (reveal_str != NULL) {
    memwipe(reveal_str, 0, strlen(reveal_str));
    tor_free(reveal_str);
  }
}

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/** From a valid srv object and an allocated config line, set the line's
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 * value to the state string representation of a shared random value. */
static void
disk_state_put_srv_line(const sr_srv_t *srv, config_line_t *line)
{
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  char encoded[SR_SRV_VALUE_BASE64_LEN + 1];
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  tor_assert(line);

  /* No SRV value thus don't add the line. This is possible since we might
   * not have a current or previous SRV value in our state. */
  if (srv == NULL) {
    return;
  }
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  sr_srv_encode(encoded, sizeof(encoded), srv);
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  tor_asprintf(&line->value, "%" PRIu64 " %s", srv->num_reveals, encoded);
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}

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/** Reset disk state that is free allocated memory and zeroed the object. */
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static void
disk_state_reset(void)
{
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  /* Free allocated memory */
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  config_free_lines(sr_disk_state->Commit);
  config_free_lines(sr_disk_state->SharedRandValues);
  config_free_lines(sr_disk_state->ExtraLines);
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  tor_free(sr_disk_state->TorVersion);

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  /* Clear other fields. */
  sr_disk_state->ValidAfter = 0;
  sr_disk_state->ValidUntil = 0;
  sr_disk_state->Version = 0;
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  /* Reset it with useful data */
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  sr_disk_state->TorVersion = tor_strdup(get_version());
}

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/** Update our disk state based on our global SR state. */
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static void
disk_state_update(void)
{
  config_line_t **next, *line;

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  if (BUG(!sr_disk_state))
    return;
  if (BUG(!sr_state))
    return;
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  /* Reset current disk state. */
  disk_state_reset();

590
  /* First, update elements that we don't need to do a construction. */
591
592
593
594
595
596
597
598
599
600
  sr_disk_state->Version = sr_state->version;
  sr_disk_state->ValidUntil = sr_state->valid_until;
  sr_disk_state->ValidAfter = sr_state->valid_after;

  /* Shared random values. */
  next = &sr_disk_state->SharedRandValues;
  if (sr_state->previous_srv != NULL) {
    *next = line = tor_malloc_zero(sizeof(config_line_t));
    line->key = tor_strdup(dstate_prev_srv_key);
    disk_state_put_srv_line(sr_state->previous_srv, line);
601
    /* Go to the next shared random value. */
602
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607
608
609
610
611
612
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615
616
617
618
619
    next = &(line->next);
  }
  if (sr_state->current_srv != NULL) {
    *next = line = tor_malloc_zero(sizeof(*line));
    line->key = tor_strdup(dstate_cur_srv_key);
    disk_state_put_srv_line(sr_state->current_srv, line);
  }

  /* Parse the commits and construct config line(s). */
  next = &sr_disk_state->Commit;
  DIGESTMAP_FOREACH(sr_state->commits, key, sr_commit_t *, commit) {
    *next = line = tor_malloc_zero(sizeof(*line));
    line->key = tor_strdup(dstate_commit_key);
    disk_state_put_commit_line(commit, line);
    next = &(line->next);
  } DIGESTMAP_FOREACH_END;
}

620
/** Load state from disk and put it into our disk state. If the state passes
621
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623
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625
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628
629
630
631
632
633
634
635
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637
 * validation, our global state will be updated with it. Return 0 on
 * success. On error, -EINVAL is returned if the state on disk did contained
 * something malformed or is unreadable. -ENOENT is returned indicating that
 * the state file is either empty of non existing. */
static int
disk_state_load_from_disk(void)
{
  int ret;
  char *fname;

  fname = get_datadir_fname(default_fname);
  ret = disk_state_load_from_disk_impl(fname);
  tor_free(fname);

  return ret;
}

638
/** Helper for disk_state_load_from_disk(). */
639
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666
STATIC int
disk_state_load_from_disk_impl(const char *fname)
{
  int ret;
  char *content = NULL;
  sr_state_t *parsed_state = NULL;
  sr_disk_state_t *disk_state = NULL;

  /* Read content of file so we can parse it. */
  if ((content = read_file_to_str(fname, 0, NULL)) == NULL) {
    log_warn(LD_FS, "SR: Unable to read SR state file %s",
             escaped(fname));
    ret = -errno;
    goto error;
  }

  {
    config_line_t *lines = NULL;
    char *errmsg = NULL;

    /* Every error in this code path will return EINVAL. */
    ret = -EINVAL;
    if (config_get_lines(content, &lines, 0) < 0) {
      config_free_lines(lines);
      goto error;
    }

    disk_state = disk_state_new(time(NULL));
667
    config_assign(get_srs_mgr(), disk_state, lines, 0, &errmsg);
668
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    config_free_lines(lines);
    if (errmsg) {
      log_warn(LD_DIR, "SR: Reading state error: %s", errmsg);
      tor_free(errmsg);
      goto error;
    }
  }

  /* So far so good, we've loaded our state file into our disk state. Let's
   * validate it and then parse it. */
  if (disk_state_validate(disk_state) < 0) {
    ret = -EINVAL;
    goto error;
  }

  parsed_state = disk_state_parse(disk_state);
  if (parsed_state == NULL) {
    ret = -EINVAL;
    goto error;
  }
  state_set(parsed_state);
  disk_state_set(disk_state);
  tor_free(content);
691
  log_info(LD_DIR, "SR: State loaded successfully from file %s", fname);
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699
  return 0;

 error:
  disk_state_free(disk_state);
  tor_free(content);
  return ret;
}

700
/** Save the disk state to disk but before that update it from the current
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719
 * state so we always have the latest. Return 0 on success else -1. */
static int
disk_state_save_to_disk(void)
{
  int ret;
  char *state, *content = NULL, *fname = NULL;
  char tbuf[ISO_TIME_LEN + 1];
  time_t now = time(NULL);

  /* If we didn't have the opportunity to setup an internal disk state,
   * don't bother saving something to disk. */
  if (sr_disk_state == NULL) {
    ret = 0;
    goto done;
  }

  /* Make sure that our disk state is up to date with our memory state
   * before saving it to disk. */
  disk_state_update();
720
  state = config_dump(get_srs_mgr(), NULL, sr_disk_state, 0, 0);
721
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743
  format_local_iso_time(tbuf, now);
  tor_asprintf(&content,
               "# Tor shared random state file last generated on %s "
               "local time\n"
               "# Other times below are in UTC\n"
               "# Please *do not* edit this file.\n\n%s",
               tbuf, state);
  tor_free(state);
  fname = get_datadir_fname(default_fname);
  if (write_str_to_file(fname, content, 0) < 0) {
    log_warn(LD_FS, "SR: Unable to write SR state to file %s", fname);
    ret = -1;
    goto done;
  }
  ret = 0;
  log_debug(LD_DIR, "SR: Saved state to file %s", fname);

 done:
  tor_free(fname);
  tor_free(content);
  return ret;
}

744
/** Reset our state to prepare for a new protocol run. Once this returns, all
745
746
747
748
 * commits in the state will be removed and freed. */
STATIC void
reset_state_for_new_protocol_run(time_t valid_after)
{
749
750
  if (BUG(!sr_state))
    return;
751
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755
756
757
758
759
760
761
762
763
764

  /* Keep counters in track */
  sr_state->n_reveal_rounds = 0;
  sr_state->n_commit_rounds = 0;
  sr_state->n_protocol_runs++;

  /* Reset valid-until */
  sr_state->valid_until = get_state_valid_until_time(valid_after);
  sr_state->valid_after = valid_after;

  /* We are in a new protocol run so cleanup commits. */
  sr_state_delete_commits();
}

765
/** This is the first round of the new protocol run starting at
766
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769
770
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 * <b>valid_after</b>. Do the necessary housekeeping. */
STATIC void
new_protocol_run(time_t valid_after)
{
  sr_commit_t *our_commitment = NULL;

  /* Only compute the srv at the end of the reveal phase. */
  if (sr_state->phase == SR_PHASE_REVEAL) {
    /* We are about to compute a new shared random value that will be set in
     * our state as the current value so rotate values. */
    state_rotate_srv();
    /* Compute the shared randomness value of the day. */
    sr_compute_srv();
  }

  /* Prepare for the new protocol run by reseting the state */
  reset_state_for_new_protocol_run(valid_after);

  /* Do some logging */
  log_info(LD_DIR, "SR: Protocol run #%" PRIu64 " starting!",
           sr_state->n_protocol_runs);

  /* Generate fresh commitments for this protocol run */
  our_commitment = sr_generate_our_commit(valid_after,
                                          get_my_v3_authority_cert());
  if (our_commitment) {
    /* Add our commitment to our state. In case we are unable to create one
     * (highly unlikely), we won't vote for this protocol run since our
     * commitment won't be in our state. */
    sr_state_add_commit(our_commitment);
  }
}

799
/** Return 1 iff the <b>next_phase</b> is a phase transition from the current
800
801
802
803
804
805
806
 * phase that is it's different. */
STATIC int
is_phase_transition(sr_phase_t next_phase)
{
  return sr_state->phase != next_phase;
}

807
/** Helper function: return a commit using the RSA fingerprint of the
808
809
810
811
812
813
814
 * authority or NULL if no such commit is known. */
static sr_commit_t *
state_query_get_commit(const char *rsa_fpr)
{
  tor_assert(rsa_fpr);
  return digestmap_get(sr_state->commits, rsa_fpr);
}
815

816
/** Helper function: This handles the GET state action using an
817
818
819
820
 * <b>obj_type</b> and <b>data</b> needed for the action. */
static void *
state_query_get_(sr_state_object_t obj_type, const void *data)
{
821
822
823
  if (BUG(!sr_state))
    return NULL;

824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
  void *obj = NULL;

  switch (obj_type) {
  case SR_STATE_OBJ_COMMIT:
  {
    obj = state_query_get_commit(data);
    break;
  }
  case SR_STATE_OBJ_COMMITS:
    obj = sr_state->commits;
    break;
  case SR_STATE_OBJ_CURSRV:
    obj = sr_state->current_srv;
    break;
  case SR_STATE_OBJ_PREVSRV:
    obj = sr_state->previous_srv;
    break;
  case SR_STATE_OBJ_PHASE:
    obj = &sr_state->phase;
    break;
  case SR_STATE_OBJ_VALID_AFTER:
  default:
    tor_assert(0);
  }
  return obj;
}

851
/** Helper function: This handles the PUT state action using an
852
853
 * <b>obj_type</b> and <b>data</b> needed for the action.
 * PUT frees the previous data before replacing it, if needed. */
854
855
856
static void
state_query_put_(sr_state_object_t obj_type, void *data)
{
857
858
859
  if (BUG(!sr_state))
    return;

860
861
862
863
864
  switch (obj_type) {
  case SR_STATE_OBJ_COMMIT:
  {
    sr_commit_t *commit = data;
    tor_assert(commit);
865
    /* commit_add_to_state() frees the old commit, if there is one */
866
867
868
869
    commit_add_to_state(commit, sr_state);
    break;
  }
  case SR_STATE_OBJ_CURSRV:
870
871
872
873
874
875
876
877
878
      /* Check if the new pointer is the same as the old one: if it is, it's
       * probably a bug. The caller may have confused current and previous,
       * or they may have forgotten to sr_srv_dup().
       * Putting NULL multiple times is allowed. */
    if (!BUG(data && sr_state->current_srv == (sr_srv_t *) data)) {
      /* We own the old SRV, so we need to free it.  */
      state_query_del_(SR_STATE_OBJ_CURSRV, NULL);
      sr_state->current_srv = (sr_srv_t *) data;
    }
879
880
    break;
  case SR_STATE_OBJ_PREVSRV:
881
882
883
884
885
886
887
888
889
      /* Check if the new pointer is the same as the old one: if it is, it's
       * probably a bug. The caller may have confused current and previous,
       * or they may have forgotten to sr_srv_dup().
       * Putting NULL multiple times is allowed. */
    if (!BUG(data && sr_state->previous_srv == (sr_srv_t *) data)) {
      /* We own the old SRV, so we need to free it.  */
      state_query_del_(SR_STATE_OBJ_PREVSRV, NULL);
      sr_state->previous_srv = (sr_srv_t *) data;
    }
890
891
892
893
894
895
896
897
898
899
900
901
902
903
    break;
  case SR_STATE_OBJ_VALID_AFTER:
    sr_state->valid_after = *((time_t *) data);
    break;
  /* It's not allowed to change the phase nor the full commitments map from
   * the state. The phase is decided during a strict process post voting and
   * the commits should be put individually. */
  case SR_STATE_OBJ_PHASE:
  case SR_STATE_OBJ_COMMITS:
  default:
    tor_assert(0);
  }
}

904
/** Helper function: This handles the DEL_ALL state action using an
905
906
907
908
 * <b>obj_type</b> and <b>data</b> needed for the action. */
static void
state_query_del_all_(sr_state_object_t obj_type)
{
909
910
911
  if (BUG(!sr_state))
    return;

912
913
914
915
916
917
918
919
920
921
  switch (obj_type) {
  case SR_STATE_OBJ_COMMIT:
  {
    /* We are in a new protocol run so cleanup commitments. */
    DIGESTMAP_FOREACH_MODIFY(sr_state->commits, key, sr_commit_t *, c) {
      sr_commit_free(c);
      MAP_DEL_CURRENT(key);
    } DIGESTMAP_FOREACH_END;
    break;
  }
922
  /* The following objects are _NOT_ supposed to be removed. */
923
924
925
926
927
928
929
930
931
932
  case SR_STATE_OBJ_CURSRV:
  case SR_STATE_OBJ_PREVSRV:
  case SR_STATE_OBJ_PHASE:
  case SR_STATE_OBJ_COMMITS:
  case SR_STATE_OBJ_VALID_AFTER:
  default:
    tor_assert(0);
  }
}

933
/** Helper function: This handles the DEL state action using an
934
935
936
937
938
939
 * <b>obj_type</b> and <b>data</b> needed for the action. */
static void
state_query_del_(sr_state_object_t obj_type, void *data)
{
  (void) data;

940
941
942
  if (BUG(!sr_state))
    return;

943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
  switch (obj_type) {
  case SR_STATE_OBJ_PREVSRV:
    tor_free(sr_state->previous_srv);
    break;
  case SR_STATE_OBJ_CURSRV:
    tor_free(sr_state->current_srv);
    break;
  case SR_STATE_OBJ_COMMIT:
  case SR_STATE_OBJ_COMMITS:
  case SR_STATE_OBJ_PHASE:
  case SR_STATE_OBJ_VALID_AFTER:
  default:
    tor_assert(0);
  }
}

959
/** Query state using an <b>action</b> for an object type <b>obj_type</b>.
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
 * The <b>data</b> pointer needs to point to an object that the action needs
 * to use and if anything is required to be returned, it is stored in
 * <b>out</b>.
 *
 * This mechanism exists so we have one single point where we synchronized
 * our memory state with our disk state for every actions that changes it.
 * We then trigger a write on disk immediately.
 *
 * This should be the only entry point to our memory state. It's used by all
 * our state accessors and should be in the future. */
static void
state_query(sr_state_action_t action, sr_state_object_t obj_type,
            void *data, void **out)
{
  switch (action) {
  case SR_STATE_ACTION_GET:
    *out = state_query_get_(obj_type, data);
    break;
  case SR_STATE_ACTION_PUT:
    state_query_put_(obj_type, data);
    break;
981
982
983
  case SR_STATE_ACTION_DEL:
    state_query_del_(obj_type, data);
    break;
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
  case SR_STATE_ACTION_DEL_ALL:
    state_query_del_all_(obj_type);
    break;
  case SR_STATE_ACTION_SAVE:
    /* Only trigger a disk state save. */
    break;
  default:
    tor_assert(0);
  }

  /* If the action actually changes the state, immediately save it to disk.
   * The following will sync the state -> disk state and then save it. */
  if (action != SR_STATE_ACTION_GET) {
    disk_state_save_to_disk();
  }
}

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