dircollate.c

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/* Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */

#define DIRCOLLATE_PRIVATE
#include "feature/dirauth/dircollate.h"
#include "feature/dirauth/dirvote.h"

#include "feature/nodelist/networkstatus_st.h"
#include "feature/nodelist/vote_routerstatus_st.h"

static void dircollator_collate_by_ed25519(dircollator_t *dc);

typedef struct ddmap_entry_s {
  HT_ENTRY(ddmap_entry_s) node;
  uint8_t d[DIGEST_LEN + DIGEST256_LEN];
  /* The nth member of this array corresponds to the vote_routerstatus_t (if
   * any) received for this digest pair from the nth voter. */
  vote_routerstatus_t *vrs_lst[FLEXIBLE_ARRAY_MEMBER];
} ddmap_entry_t;

#define ddmap_entry_free(e) \
  FREE_AND_NULL(ddmap_entry_t, ddmap_entry_free_, (e))

static void
ddmap_entry_free_(ddmap_entry_t *e)
{
  tor_free(e);
}

static ddmap_entry_t *
ddmap_entry_new(int n_votes)
{
  return tor_malloc_zero(offsetof(ddmap_entry_t, vrs_lst) +
                         sizeof(vote_routerstatus_t *) * n_votes);
}

static unsigned
ddmap_entry_hash(const ddmap_entry_t *ent)
{
  return (unsigned) siphash24g(ent->d, sizeof(ent->d));
}

static unsigned
ddmap_entry_eq(const ddmap_entry_t *a, const ddmap_entry_t *b)
{
  return fast_memeq(a->d, b->d, sizeof(a->d));
}

static void
ddmap_entry_set_digests(ddmap_entry_t *ent,
                        const uint8_t *rsa_sha1,
                        const uint8_t *ed25519)
{
  memcpy(ent->d, rsa_sha1, DIGEST_LEN);
  memcpy(ent->d + DIGEST_LEN, ed25519, DIGEST256_LEN);
}

HT_PROTOTYPE(double_digest_map, ddmap_entry_s, node, ddmap_entry_hash,
             ddmap_entry_eq)
HT_GENERATE2(double_digest_map, ddmap_entry_s, node, ddmap_entry_hash,
             ddmap_entry_eq, 0.6, tor_reallocarray, tor_free_)


static void
dircollator_add_routerstatus(dircollator_t *dc,
                             int vote_num,
                             networkstatus_t *vote,
                             vote_routerstatus_t *vrs)
{
  const char *id = vrs->status.identity_digest;

  /* Clear this flag; we might set it later during the voting process */
  vrs->ed25519_reflects_consensus = 0;

  (void) vote; // We don't currently need this.

  /* First, add this item to the appropriate RSA-SHA-Id array. */
  vote_routerstatus_t **vrs_lst = digestmap_get(dc->by_rsa_sha1, id);
  if (NULL == vrs_lst) {
    vrs_lst = tor_calloc(dc->n_votes, sizeof(vote_routerstatus_t *));
    digestmap_set(dc->by_rsa_sha1, id, vrs_lst);
  }
  tor_assert(vrs_lst[vote_num] == NULL);
  vrs_lst[vote_num] = vrs;

  const uint8_t *ed = vrs->ed25519_id;

  if (! vrs->has_ed25519_listing)
    return;

  /* Now add it to the appropriate <Ed,RSA-SHA-Id> array. */
  ddmap_entry_t search, *found;
  memset(&search, 0, sizeof(search));
  ddmap_entry_set_digests(&search, (const uint8_t *)id, ed);
  found = HT_FIND(double_digest_map, &dc->by_both_ids, &search);
  if (NULL == found) {
    found = ddmap_entry_new(dc->n_votes);
    ddmap_entry_set_digests(found, (const uint8_t *)id, ed);
    HT_INSERT(double_digest_map, &dc->by_both_ids, found);
  }
  vrs_lst = found->vrs_lst;
  tor_assert(vrs_lst[vote_num] == NULL);
  vrs_lst[vote_num] = vrs;
}

dircollator_t *
dircollator_new(int n_votes, int n_authorities)
{
  dircollator_t *dc = tor_malloc_zero(sizeof(dircollator_t));

  tor_assert(n_votes <= n_authorities);

  dc->n_votes = n_votes;
  dc->n_authorities = n_authorities;

  dc->by_rsa_sha1 = digestmap_new();
  HT_INIT(double_digest_map, &dc->by_both_ids);

  return dc;
}

void
dircollator_free_(dircollator_t *dc)
{
  if (!dc)
    return;

  if (dc->by_collated_rsa_sha1 != dc->by_rsa_sha1)
    digestmap_free(dc->by_collated_rsa_sha1, NULL);

  digestmap_free(dc->by_rsa_sha1, tor_free_);
  smartlist_free(dc->all_rsa_sha1_lst);

  ddmap_entry_t **e, **next, *this;
  for (e = HT_START(double_digest_map, &dc->by_both_ids);
       e != NULL; e = next) {
    this = *e;
    next = HT_NEXT_RMV(double_digest_map, &dc->by_both_ids, e);
    ddmap_entry_free(this);
  }
  HT_CLEAR(double_digest_map, &dc->by_both_ids);

  tor_free(dc);
}

void
dircollator_add_vote(dircollator_t *dc, networkstatus_t *v)
{
  tor_assert(v->type == NS_TYPE_VOTE);
  tor_assert(dc->next_vote_num < dc->n_votes);
  tor_assert(!dc->is_collated);

  const int votenum = dc->next_vote_num++;

  SMARTLIST_FOREACH_BEGIN(v->routerstatus_list, vote_routerstatus_t *, vrs) {
    dircollator_add_routerstatus(dc, votenum, v, vrs);
  } SMARTLIST_FOREACH_END(vrs);
}

void
dircollator_collate(dircollator_t *dc, int consensus_method)
{
  (void) consensus_method;

  tor_assert(!dc->is_collated);
  dc->all_rsa_sha1_lst = smartlist_new();

  dircollator_collate_by_ed25519(dc);

  smartlist_sort_digests(dc->all_rsa_sha1_lst);
  dc->is_collated = 1;
}

static void
dircollator_collate_by_ed25519(dircollator_t *dc)
{
  const int total_authorities = dc->n_authorities;
  digestmap_t *rsa_digests = digestmap_new();

  ddmap_entry_t **iter;

  /* Go over all <ed,rsa> pairs */
  HT_FOREACH(iter, double_digest_map, &dc->by_both_ids) {
    ddmap_entry_t *ent = *iter;
    int n = 0, i;
    for (i = 0; i < dc->n_votes; ++i) {
      if (ent->vrs_lst[i] != NULL)
        ++n;
    }

    /* If not enough authorties listed this exact <ed,rsa> pair,
     * don't include it. */
    if (n <= total_authorities / 2)
      continue;

    /* Now consider whether there are any other entries with the same
     * RSA key (but with possibly different or missing ed value). */
    vote_routerstatus_t **vrs_lst2 = digestmap_get(dc->by_rsa_sha1,
                                                   (char*)ent->d);
    tor_assert(vrs_lst2);

    for (i = 0; i < dc->n_votes; ++i) {
      if (ent->vrs_lst[i] != NULL) {
        ent->vrs_lst[i]->ed25519_reflects_consensus = 1;
      } else if (vrs_lst2[i] && ! vrs_lst2[i]->has_ed25519_listing) {
        ent->vrs_lst[i] = vrs_lst2[i];
      }
    }

    /* Record that we have seen this RSA digest. */
    digestmap_set(rsa_digests, (char*)ent->d, ent->vrs_lst);
    smartlist_add(dc->all_rsa_sha1_lst, ent->d);
  }

  /* Now look over all entries with an RSA digest, looking for RSA digests
   * we didn't put in yet.
   */
  DIGESTMAP_FOREACH(dc->by_rsa_sha1, k, vote_routerstatus_t **, vrs_lst) {
    if (digestmap_get(rsa_digests, k) != NULL)
      continue; /* We already included this RSA digest */

    int n = 0, i;
    for (i = 0; i < dc->n_votes; ++i) {
      if (vrs_lst[i] != NULL)
        ++n;
    }

    if (n <= total_authorities / 2)
      continue; /* Not enough votes */

    digestmap_set(rsa_digests, k, vrs_lst);
    smartlist_add(dc->all_rsa_sha1_lst, (char *)k);
  } DIGESTMAP_FOREACH_END;

  dc->by_collated_rsa_sha1 = rsa_digests;
}

int
dircollator_n_routers(dircollator_t *dc)
{
  tor_assert(dc->is_collated);
  return smartlist_len(dc->all_rsa_sha1_lst);
}

vote_routerstatus_t **
dircollator_get_votes_for_router(dircollator_t *dc, int idx)
{
  tor_assert(dc->is_collated);
  tor_assert(idx < smartlist_len(dc->all_rsa_sha1_lst));
  return digestmap_get(dc->by_collated_rsa_sha1,
                       smartlist_get(dc->all_rsa_sha1_lst, idx));
}