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dirvote.c
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dirvote.c
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/* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#define DIRVOTE_PRIVATE
#include "or.h"
#include "config.h"
#include "dircollate.h"
#include "directory.h"
#include "dirserv.h"
#include "dirvote.h"
#include "microdesc.h"
#include "networkstatus.h"
#include "policies.h"
#include "protover.h"
#include "rephist.h"
#include "router.h"
#include "routerkeys.h"
#include "routerlist.h"
#include "routerparse.h"
#include "entrynodes.h" /* needed for guardfraction methods */
#include "torcert.h"
#include "shared_random_state.h"
/**
* \file dirvote.c
* \brief Functions to compute directory consensus, and schedule voting.
*
* This module is the center of the consensus-voting based directory
* authority system. With this system, a set of authorities first
* publish vote based on their opinions of the network, and then compute
* a consensus from those votes. Each authority signs the consensus,
* and clients trust the consensus if enough known authorities have
* signed it.
*
* The code in this module is only invoked on directory authorities. It's
* responsible for:
*
* <ul>
* <li>Generating this authority's vote networkstatus, based on the
* authority's view of the network as represented in dirserv.c
* <li>Formatting the vote networkstatus objects.
* <li>Generating the microdescriptors that correspond to our own
* vote.
* <li>Sending votes to all the other authorities.
* <li>Trying to fetch missing votes from other authorities.
* <li>Computing the consensus from a set of votes, as well as
* a "detached signature" object for other authorities to fetch.
* <li>Collecting other authorities' signatures on the same consensus,
* until there are enough.
* <li>Publishing the consensus to the reset of the directory system.
* <li>Scheduling all of the above operations.
* </ul>
*
* The main entry points are in dirvote_act(), which handles scheduled
* actions; and dirvote_add_vote() and dirvote_add_signatures(), which
* handle uploaded and downloaded votes and signatures.
*
* (See dir-spec.txt from torspec.git for a complete specification of
* the directory protocol and voting algorithms.)
**/
/** A consensus that we have built and are appending signatures to. Once it's
* time to publish it, it will become an active consensus if it accumulates
* enough signatures. */
typedef struct pending_consensus_t {
/** The body of the consensus that we're currently building. Once we
* have it built, it goes into dirserv.c */
char *body;
/** The parsed in-progress consensus document. */
networkstatus_t *consensus;
} pending_consensus_t;
/* DOCDOC dirvote_add_signatures_to_all_pending_consensuses */
static int dirvote_add_signatures_to_all_pending_consensuses(
const char *detached_signatures_body,
const char *source,
const char **msg_out);
static int dirvote_add_signatures_to_pending_consensus(
pending_consensus_t *pc,
ns_detached_signatures_t *sigs,
const char *source,
int severity,
const char **msg_out);
static char *list_v3_auth_ids(void);
static void dirvote_fetch_missing_votes(void);
static void dirvote_fetch_missing_signatures(void);
static int dirvote_perform_vote(void);
static void dirvote_clear_votes(int all_votes);
static int dirvote_compute_consensuses(void);
static int dirvote_publish_consensus(void);
/* =====
* Voting
* =====*/
/* If <b>opt_value</b> is non-NULL, return "keyword opt_value\n" in a new
* string. Otherwise return a new empty string. */
static char *
format_line_if_present(const char *keyword, const char *opt_value)
{
if (opt_value) {
char *result = NULL;
tor_asprintf(&result, "%s %s\n", keyword, opt_value);
return result;
} else {
return tor_strdup("");
}
}
/** Format the recommended/required-relay-client protocols lines for a vote in
* a newly allocated string, and return that string. */
static char *
format_protocols_lines_for_vote(const networkstatus_t *v3_ns)
{
char *recommended_relay_protocols_line = NULL;
char *recommended_client_protocols_line = NULL;
char *required_relay_protocols_line = NULL;
char *required_client_protocols_line = NULL;
recommended_relay_protocols_line =
format_line_if_present("recommended-relay-protocols",
v3_ns->recommended_relay_protocols);
recommended_client_protocols_line =
format_line_if_present("recommended-client-protocols",
v3_ns->recommended_client_protocols);
required_relay_protocols_line =
format_line_if_present("required-relay-protocols",
v3_ns->required_relay_protocols);
required_client_protocols_line =
format_line_if_present("required-client-protocols",
v3_ns->required_client_protocols);
char *result = NULL;
tor_asprintf(&result, "%s%s%s%s",
recommended_relay_protocols_line,
recommended_client_protocols_line,
required_relay_protocols_line,
required_client_protocols_line);
tor_free(recommended_relay_protocols_line);
tor_free(recommended_client_protocols_line);
tor_free(required_relay_protocols_line);
tor_free(required_client_protocols_line);
return result;
}
/** Return a new string containing the string representation of the vote in
* <b>v3_ns</b>, signed with our v3 signing key <b>private_signing_key</b>.
* For v3 authorities. */
STATIC char *
format_networkstatus_vote(crypto_pk_t *private_signing_key,
networkstatus_t *v3_ns)
{
smartlist_t *chunks = smartlist_new();
char *packages = NULL;
char fingerprint[FINGERPRINT_LEN+1];
char digest[DIGEST_LEN];
uint32_t addr;
char *protocols_lines = NULL;
char *client_versions_line = NULL, *server_versions_line = NULL;
char *shared_random_vote_str = NULL;
networkstatus_voter_info_t *voter;
char *status = NULL;
tor_assert(private_signing_key);
tor_assert(v3_ns->type == NS_TYPE_VOTE || v3_ns->type == NS_TYPE_OPINION);
voter = smartlist_get(v3_ns->voters, 0);
addr = voter->addr;
base16_encode(fingerprint, sizeof(fingerprint),
v3_ns->cert->cache_info.identity_digest, DIGEST_LEN);
client_versions_line = format_line_if_present("client-versions",
v3_ns->client_versions);
server_versions_line = format_line_if_present("server-versions",
v3_ns->server_versions);
protocols_lines = format_protocols_lines_for_vote(v3_ns);
if (v3_ns->package_lines) {
smartlist_t *tmp = smartlist_new();
SMARTLIST_FOREACH(v3_ns->package_lines, const char *, p,
if (validate_recommended_package_line(p))
smartlist_add_asprintf(tmp, "package %s\n", p));
smartlist_sort_strings(tmp);
packages = smartlist_join_strings(tmp, "", 0, NULL);
SMARTLIST_FOREACH(tmp, char *, cp, tor_free(cp));
smartlist_free(tmp);
} else {
packages = tor_strdup("");
}
/* Get shared random commitments/reveals line(s). */
shared_random_vote_str = sr_get_string_for_vote();
{
char published[ISO_TIME_LEN+1];
char va[ISO_TIME_LEN+1];
char fu[ISO_TIME_LEN+1];
char vu[ISO_TIME_LEN+1];
char *flags = smartlist_join_strings(v3_ns->known_flags, " ", 0, NULL);
/* XXXX Abstraction violation: should be pulling a field out of v3_ns.*/
char *flag_thresholds = dirserv_get_flag_thresholds_line();
char *params;
authority_cert_t *cert = v3_ns->cert;
char *methods =
make_consensus_method_list(MIN_SUPPORTED_CONSENSUS_METHOD,
MAX_SUPPORTED_CONSENSUS_METHOD, " ");
format_iso_time(published, v3_ns->published);
format_iso_time(va, v3_ns->valid_after);
format_iso_time(fu, v3_ns->fresh_until);
format_iso_time(vu, v3_ns->valid_until);
if (v3_ns->net_params)
params = smartlist_join_strings(v3_ns->net_params, " ", 0, NULL);
else
params = tor_strdup("");
tor_assert(cert);
smartlist_add_asprintf(chunks,
"network-status-version 3\n"
"vote-status %s\n"
"consensus-methods %s\n"
"published %s\n"
"valid-after %s\n"
"fresh-until %s\n"
"valid-until %s\n"
"voting-delay %d %d\n"
"%s%s" /* versions */
"%s" /* protocols */
"%s" /* packages */
"known-flags %s\n"
"flag-thresholds %s\n"
"params %s\n"
"dir-source %s %s %s %s %d %d\n"
"contact %s\n"
"%s", /* shared randomness information */
v3_ns->type == NS_TYPE_VOTE ? "vote" : "opinion",
methods,
published, va, fu, vu,
v3_ns->vote_seconds, v3_ns->dist_seconds,
client_versions_line,
server_versions_line,
protocols_lines,
packages,
flags,
flag_thresholds,
params,
voter->nickname, fingerprint, voter->address,
fmt_addr32(addr), voter->dir_port, voter->or_port,
voter->contact,
shared_random_vote_str ?
shared_random_vote_str : "");
tor_free(params);
tor_free(flags);
tor_free(flag_thresholds);
tor_free(methods);
tor_free(shared_random_vote_str);
if (!tor_digest_is_zero(voter->legacy_id_digest)) {
char fpbuf[HEX_DIGEST_LEN+1];
base16_encode(fpbuf, sizeof(fpbuf), voter->legacy_id_digest, DIGEST_LEN);
smartlist_add_asprintf(chunks, "legacy-dir-key %s\n", fpbuf);
}
smartlist_add(chunks, tor_strndup(cert->cache_info.signed_descriptor_body,
cert->cache_info.signed_descriptor_len));
}
SMARTLIST_FOREACH_BEGIN(v3_ns->routerstatus_list, vote_routerstatus_t *,
vrs) {
char *rsf;
vote_microdesc_hash_t *h;
rsf = routerstatus_format_entry(&vrs->status,
vrs->version, vrs->protocols,
NS_V3_VOTE,
ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD,
vrs);
if (rsf)
smartlist_add(chunks, rsf);
for (h = vrs->microdesc; h; h = h->next) {
smartlist_add_strdup(chunks, h->microdesc_hash_line);
}
} SMARTLIST_FOREACH_END(vrs);
smartlist_add_strdup(chunks, "directory-footer\n");
/* The digest includes everything up through the space after
* directory-signature. (Yuck.) */
crypto_digest_smartlist(digest, DIGEST_LEN, chunks,
"directory-signature ", DIGEST_SHA1);
{
char signing_key_fingerprint[FINGERPRINT_LEN+1];
if (crypto_pk_get_fingerprint(private_signing_key,
signing_key_fingerprint, 0)<0) {
log_warn(LD_BUG, "Unable to get fingerprint for signing key");
goto err;
}
smartlist_add_asprintf(chunks, "directory-signature %s %s\n", fingerprint,
signing_key_fingerprint);
}
{
char *sig = router_get_dirobj_signature(digest, DIGEST_LEN,
private_signing_key);
if (!sig) {
log_warn(LD_BUG, "Unable to sign networkstatus vote.");
goto err;
}
smartlist_add(chunks, sig);
}
status = smartlist_join_strings(chunks, "", 0, NULL);
{
networkstatus_t *v;
if (!(v = networkstatus_parse_vote_from_string(status, NULL,
v3_ns->type))) {
log_err(LD_BUG,"Generated a networkstatus %s we couldn't parse: "
"<<%s>>",
v3_ns->type == NS_TYPE_VOTE ? "vote" : "opinion", status);
goto err;
}
networkstatus_vote_free(v);
}
goto done;
err:
tor_free(status);
done:
tor_free(client_versions_line);
tor_free(server_versions_line);
tor_free(protocols_lines);
tor_free(packages);
SMARTLIST_FOREACH(chunks, char *, cp, tor_free(cp));
smartlist_free(chunks);
return status;
}
/* =====
* Consensus generation
* ===== */
/** Given a vote <b>vote</b> (not a consensus!), return its associated
* networkstatus_voter_info_t. */
static networkstatus_voter_info_t *
get_voter(const networkstatus_t *vote)
{
tor_assert(vote);
tor_assert(vote->type == NS_TYPE_VOTE);
tor_assert(vote->voters);
tor_assert(smartlist_len(vote->voters) == 1);
return smartlist_get(vote->voters, 0);
}
/** Return the signature made by <b>voter</b> using the algorithm
* <b>alg</b>, or NULL if none is found. */
document_signature_t *
voter_get_sig_by_algorithm(const networkstatus_voter_info_t *voter,
digest_algorithm_t alg)
{
if (!voter->sigs)
return NULL;
SMARTLIST_FOREACH(voter->sigs, document_signature_t *, sig,
if (sig->alg == alg)
return sig);
return NULL;
}
/** Temporary structure used in constructing a list of dir-source entries
* for a consensus. One of these is generated for every vote, and one more
* for every legacy key in each vote. */
typedef struct dir_src_ent_t {
networkstatus_t *v;
const char *digest;
int is_legacy;
} dir_src_ent_t;
/** Helper for sorting networkstatus_t votes (not consensuses) by the
* hash of their voters' identity digests. */
static int
compare_votes_by_authority_id_(const void **_a, const void **_b)
{
const networkstatus_t *a = *_a, *b = *_b;
return fast_memcmp(get_voter(a)->identity_digest,
get_voter(b)->identity_digest, DIGEST_LEN);
}
/** Helper: Compare the dir_src_ent_ts in *<b>_a</b> and *<b>_b</b> by
* their identity digests, and return -1, 0, or 1 depending on their
* ordering */
static int
compare_dir_src_ents_by_authority_id_(const void **_a, const void **_b)
{
const dir_src_ent_t *a = *_a, *b = *_b;
const networkstatus_voter_info_t *a_v = get_voter(a->v),
*b_v = get_voter(b->v);
const char *a_id, *b_id;
a_id = a->is_legacy ? a_v->legacy_id_digest : a_v->identity_digest;
b_id = b->is_legacy ? b_v->legacy_id_digest : b_v->identity_digest;
return fast_memcmp(a_id, b_id, DIGEST_LEN);
}
/** Given a sorted list of strings <b>in</b>, add every member to <b>out</b>
* that occurs more than <b>min</b> times. */
static void
get_frequent_members(smartlist_t *out, smartlist_t *in, int min)
{
char *cur = NULL;
int count = 0;
SMARTLIST_FOREACH_BEGIN(in, char *, cp) {
if (cur && !strcmp(cp, cur)) {
++count;
} else {
if (count > min)
smartlist_add(out, cur);
cur = cp;
count = 1;
}
} SMARTLIST_FOREACH_END(cp);
if (count > min)
smartlist_add(out, cur);
}
/** Given a sorted list of strings <b>lst</b>, return the member that appears
* most. Break ties in favor of later-occurring members. */
#define get_most_frequent_member(lst) \
smartlist_get_most_frequent_string(lst)
/** Return 0 if and only if <b>a</b> and <b>b</b> are routerstatuses
* that come from the same routerinfo, with the same derived elements.
*/
static int
compare_vote_rs(const vote_routerstatus_t *a, const vote_routerstatus_t *b)
{
int r;
tor_assert(a);
tor_assert(b);
if ((r = fast_memcmp(a->status.identity_digest, b->status.identity_digest,
DIGEST_LEN)))
return r;
if ((r = fast_memcmp(a->status.descriptor_digest,
b->status.descriptor_digest,
DIGEST_LEN)))
return r;
/* If we actually reached this point, then the identities and
* the descriptor digests matched, so somebody is making SHA1 collisions.
*/
#define CMP_FIELD(utype, itype, field) do { \
utype aval = (utype) (itype) a->status.field; \
utype bval = (utype) (itype) b->status.field; \
utype u = bval - aval; \
itype r2 = (itype) u; \
if (r2 < 0) { \
return -1; \
} else if (r2 > 0) { \
return 1; \
} \
} while (0)
CMP_FIELD(uint64_t, int64_t, published_on);
if ((r = strcmp(b->status.nickname, a->status.nickname)))
return r;
CMP_FIELD(unsigned, int, addr);
CMP_FIELD(unsigned, int, or_port);
CMP_FIELD(unsigned, int, dir_port);
return 0;
}
/** Helper for sorting routerlists based on compare_vote_rs. */
static int
compare_vote_rs_(const void **_a, const void **_b)
{
const vote_routerstatus_t *a = *_a, *b = *_b;
return compare_vote_rs(a,b);
}
/** Helper for sorting OR ports. */
static int
compare_orports_(const void **_a, const void **_b)
{
const tor_addr_port_t *a = *_a, *b = *_b;
int r;
if ((r = tor_addr_compare(&a->addr, &b->addr, CMP_EXACT)))
return r;
if ((r = (((int) b->port) - ((int) a->port))))
return r;
return 0;
}
/** Given a list of vote_routerstatus_t, all for the same router identity,
* return whichever is most frequent, breaking ties in favor of more
* recently published vote_routerstatus_t and in case of ties there,
* in favor of smaller descriptor digest.
*/
static vote_routerstatus_t *
compute_routerstatus_consensus(smartlist_t *votes, int consensus_method,
char *microdesc_digest256_out,
tor_addr_port_t *best_alt_orport_out)
{
vote_routerstatus_t *most = NULL, *cur = NULL;
int most_n = 0, cur_n = 0;
time_t most_published = 0;
/* compare_vote_rs_() sorts the items by identity digest (all the same),
* then by SD digest. That way, if we have a tie that the published_on
* date cannot break, we use the descriptor with the smaller digest.
*/
smartlist_sort(votes, compare_vote_rs_);
SMARTLIST_FOREACH_BEGIN(votes, vote_routerstatus_t *, rs) {
if (cur && !compare_vote_rs(cur, rs)) {
++cur_n;
} else {
if (cur && (cur_n > most_n ||
(cur_n == most_n &&
cur->status.published_on > most_published))) {
most = cur;
most_n = cur_n;
most_published = cur->status.published_on;
}
cur_n = 1;
cur = rs;
}
} SMARTLIST_FOREACH_END(rs);
if (cur_n > most_n ||
(cur && cur_n == most_n && cur->status.published_on > most_published)) {
most = cur;
// most_n = cur_n; // unused after this point.
// most_published = cur->status.published_on; // unused after this point.
}
tor_assert(most);
/* If we're producing "a" lines, vote on potential alternative (sets
* of) OR port(s) in the winning routerstatuses.
*
* XXX prop186 There's at most one alternative OR port (_the_ IPv6
* port) for now. */
if (consensus_method >= MIN_METHOD_FOR_A_LINES && best_alt_orport_out) {
smartlist_t *alt_orports = smartlist_new();
const tor_addr_port_t *most_alt_orport = NULL;
SMARTLIST_FOREACH_BEGIN(votes, vote_routerstatus_t *, rs) {
tor_assert(rs);
if (compare_vote_rs(most, rs) == 0 &&
!tor_addr_is_null(&rs->status.ipv6_addr)
&& rs->status.ipv6_orport) {
smartlist_add(alt_orports, tor_addr_port_new(&rs->status.ipv6_addr,
rs->status.ipv6_orport));
}
} SMARTLIST_FOREACH_END(rs);
smartlist_sort(alt_orports, compare_orports_);
most_alt_orport = smartlist_get_most_frequent(alt_orports,
compare_orports_);
if (most_alt_orport) {
memcpy(best_alt_orport_out, most_alt_orport, sizeof(tor_addr_port_t));
log_debug(LD_DIR, "\"a\" line winner for %s is %s",
most->status.nickname,
fmt_addrport(&most_alt_orport->addr, most_alt_orport->port));
}
SMARTLIST_FOREACH(alt_orports, tor_addr_port_t *, ap, tor_free(ap));
smartlist_free(alt_orports);
}
if (microdesc_digest256_out) {
smartlist_t *digests = smartlist_new();
const uint8_t *best_microdesc_digest;
SMARTLIST_FOREACH_BEGIN(votes, vote_routerstatus_t *, rs) {
char d[DIGEST256_LEN];
if (compare_vote_rs(rs, most))
continue;
if (!vote_routerstatus_find_microdesc_hash(d, rs, consensus_method,
DIGEST_SHA256))
smartlist_add(digests, tor_memdup(d, sizeof(d)));
} SMARTLIST_FOREACH_END(rs);
smartlist_sort_digests256(digests);
best_microdesc_digest = smartlist_get_most_frequent_digest256(digests);
if (best_microdesc_digest)
memcpy(microdesc_digest256_out, best_microdesc_digest, DIGEST256_LEN);
SMARTLIST_FOREACH(digests, char *, cp, tor_free(cp));
smartlist_free(digests);
}
return most;
}
/** Sorting helper: compare two strings based on their values as base-ten
* positive integers. (Non-integers are treated as prior to all integers, and
* compared lexically.) */
static int
cmp_int_strings_(const void **_a, const void **_b)
{
const char *a = *_a, *b = *_b;
int ai = (int)tor_parse_long(a, 10, 1, INT_MAX, NULL, NULL);
int bi = (int)tor_parse_long(b, 10, 1, INT_MAX, NULL, NULL);
if (ai<bi) {
return -1;
} else if (ai==bi) {
if (ai == 0) /* Parsing failed. */
return strcmp(a, b);
return 0;
} else {
return 1;
}
}
/** Given a list of networkstatus_t votes, determine and return the number of
* the highest consensus method that is supported by 2/3 of the voters. */
static int
compute_consensus_method(smartlist_t *votes)
{
smartlist_t *all_methods = smartlist_new();
smartlist_t *acceptable_methods = smartlist_new();
smartlist_t *tmp = smartlist_new();
int min = (smartlist_len(votes) * 2) / 3;
int n_ok;
int result;
SMARTLIST_FOREACH(votes, networkstatus_t *, vote,
{
tor_assert(vote->supported_methods);
smartlist_add_all(tmp, vote->supported_methods);
smartlist_sort(tmp, cmp_int_strings_);
smartlist_uniq(tmp, cmp_int_strings_, NULL);
smartlist_add_all(all_methods, tmp);
smartlist_clear(tmp);
});
smartlist_sort(all_methods, cmp_int_strings_);
get_frequent_members(acceptable_methods, all_methods, min);
n_ok = smartlist_len(acceptable_methods);
if (n_ok) {
const char *best = smartlist_get(acceptable_methods, n_ok-1);
result = (int)tor_parse_long(best, 10, 1, INT_MAX, NULL, NULL);
} else {
result = 1;
}
smartlist_free(tmp);
smartlist_free(all_methods);
smartlist_free(acceptable_methods);
return result;
}
/** Return true iff <b>method</b> is a consensus method that we support. */
static int
consensus_method_is_supported(int method)
{
if (method == MIN_METHOD_FOR_ED25519_ID_IN_MD) {
/* This method was broken due to buggy code accidently left in
* dircollate.c; do not actually use it.
*/
return 0;
}
return (method >= MIN_SUPPORTED_CONSENSUS_METHOD) &&
(method <= MAX_SUPPORTED_CONSENSUS_METHOD);
}
/** Return a newly allocated string holding the numbers between low and high
* (inclusive) that are supported consensus methods. */
STATIC char *
make_consensus_method_list(int low, int high, const char *separator)
{
char *list;
int i;
smartlist_t *lst;
lst = smartlist_new();
for (i = low; i <= high; ++i) {
if (!consensus_method_is_supported(i))
continue;
smartlist_add_asprintf(lst, "%d", i);
}
list = smartlist_join_strings(lst, separator, 0, NULL);
tor_assert(list);
SMARTLIST_FOREACH(lst, char *, cp, tor_free(cp));
smartlist_free(lst);
return list;
}
/** Helper: given <b>lst</b>, a list of version strings such that every
* version appears once for every versioning voter who recommends it, return a
* newly allocated string holding the resulting client-versions or
* server-versions list. May change contents of <b>lst</b> */
static char *
compute_consensus_versions_list(smartlist_t *lst, int n_versioning)
{
int min = n_versioning / 2;
smartlist_t *good = smartlist_new();
char *result;
sort_version_list(lst, 0);
get_frequent_members(good, lst, min);
result = smartlist_join_strings(good, ",", 0, NULL);
smartlist_free(good);
return result;
}
/** Given a list of K=V values, return the int32_t value corresponding to
* KEYWORD=, or default_val if no such value exists, or if the value is
* corrupt.
*/
STATIC int32_t
dirvote_get_intermediate_param_value(const smartlist_t *param_list,
const char *keyword,
int32_t default_val)
{
unsigned int n_found = 0;
int32_t value = default_val;
SMARTLIST_FOREACH_BEGIN(param_list, const char *, k_v_pair) {
if (!strcmpstart(k_v_pair, keyword) && k_v_pair[strlen(keyword)] == '=') {
const char *integer_str = &k_v_pair[strlen(keyword)+1];
int ok;
value = (int32_t)
tor_parse_long(integer_str, 10, INT32_MIN, INT32_MAX, &ok, NULL);
if (BUG(! ok))
return default_val;
++n_found;
}
} SMARTLIST_FOREACH_END(k_v_pair);
if (n_found == 1) {
return value;
} else {
tor_assert_nonfatal(n_found == 0);
return default_val;
}
}
/** Minimum number of directory authorities voting for a parameter to
* include it in the consensus, if consensus method 12 or later is to be
* used. See proposal 178 for details. */
#define MIN_VOTES_FOR_PARAM 3
/** Helper: given a list of valid networkstatus_t, return a new smartlist
* containing the contents of the consensus network parameter set.
*/
STATIC smartlist_t *
dirvote_compute_params(smartlist_t *votes, int method, int total_authorities)
{
int i;
int32_t *vals;
int cur_param_len;
const char *cur_param;
const char *eq;
const int n_votes = smartlist_len(votes);
smartlist_t *output;
smartlist_t *param_list = smartlist_new();
(void) method;
/* We require that the parameter lists in the votes are well-formed: that
is, that their keywords are unique and sorted, and that their values are
between INT32_MIN and INT32_MAX inclusive. This should be guaranteed by
the parsing code. */
vals = tor_calloc(n_votes, sizeof(int));
SMARTLIST_FOREACH_BEGIN(votes, networkstatus_t *, v) {
if (!v->net_params)
continue;
smartlist_add_all(param_list, v->net_params);
} SMARTLIST_FOREACH_END(v);
if (smartlist_len(param_list) == 0) {
tor_free(vals);
return param_list;
}
smartlist_sort_strings(param_list);
i = 0;
cur_param = smartlist_get(param_list, 0);
eq = strchr(cur_param, '=');
tor_assert(eq);
cur_param_len = (int)(eq+1 - cur_param);
output = smartlist_new();
SMARTLIST_FOREACH_BEGIN(param_list, const char *, param) {
/* resolve spurious clang shallow analysis null pointer errors */
tor_assert(param);
const char *next_param;
int ok=0;
eq = strchr(param, '=');
tor_assert(i<n_votes); /* Make sure we prevented vote-stuffing. */
vals[i++] = (int32_t)
tor_parse_long(eq+1, 10, INT32_MIN, INT32_MAX, &ok, NULL);
tor_assert(ok); /* Already checked these when parsing. */
if (param_sl_idx+1 == smartlist_len(param_list))
next_param = NULL;
else
next_param = smartlist_get(param_list, param_sl_idx+1);
if (!next_param || strncmp(next_param, param, cur_param_len)) {
/* We've reached the end of a series. */
/* Make sure enough authorities voted on this param, unless the
* the consensus method we use is too old for that. */
if (i > total_authorities/2 ||
i >= MIN_VOTES_FOR_PARAM) {
int32_t median = median_int32(vals, i);
char *out_string = tor_malloc(64+cur_param_len);
memcpy(out_string, param, cur_param_len);
tor_snprintf(out_string+cur_param_len,64, "%ld", (long)median);
smartlist_add(output, out_string);
}
i = 0;
if (next_param) {
eq = strchr(next_param, '=');
cur_param_len = (int)(eq+1 - next_param);
}
}
} SMARTLIST_FOREACH_END(param);
smartlist_free(param_list);
tor_free(vals);
return output;
}
#define RANGE_CHECK(a,b,c,d,e,f,g,mx) \
((a) >= 0 && (a) <= (mx) && (b) >= 0 && (b) <= (mx) && \
(c) >= 0 && (c) <= (mx) && (d) >= 0 && (d) <= (mx) && \
(e) >= 0 && (e) <= (mx) && (f) >= 0 && (f) <= (mx) && \
(g) >= 0 && (g) <= (mx))
#define CHECK_EQ(a, b, margin) \
((a)-(b) >= 0 ? (a)-(b) <= (margin) : (b)-(a) <= (margin))
typedef enum {
BW_WEIGHTS_NO_ERROR = 0,
BW_WEIGHTS_RANGE_ERROR = 1,
BW_WEIGHTS_SUMG_ERROR = 2,
BW_WEIGHTS_SUME_ERROR = 3,
BW_WEIGHTS_SUMD_ERROR = 4,
BW_WEIGHTS_BALANCE_MID_ERROR = 5,
BW_WEIGHTS_BALANCE_EG_ERROR = 6
} bw_weights_error_t;
/**
* Verify that any weightings satisfy the balanced formulas.
*/
static bw_weights_error_t
networkstatus_check_weights(int64_t Wgg, int64_t Wgd, int64_t Wmg,
int64_t Wme, int64_t Wmd, int64_t Wee,
int64_t Wed, int64_t scale, int64_t G,
int64_t M, int64_t E, int64_t D, int64_t T,
int64_t margin, int do_balance) {
bw_weights_error_t berr = BW_WEIGHTS_NO_ERROR;
// Wed + Wmd + Wgd == 1
if (!CHECK_EQ(Wed + Wmd + Wgd, scale, margin)) {
berr = BW_WEIGHTS_SUMD_ERROR;
goto out;
}
// Wmg + Wgg == 1
if (!CHECK_EQ(Wmg + Wgg, scale, margin)) {
berr = BW_WEIGHTS_SUMG_ERROR;
goto out;
}
// Wme + Wee == 1
if (!CHECK_EQ(Wme + Wee, scale, margin)) {
berr = BW_WEIGHTS_SUME_ERROR;
goto out;
}
// Verify weights within range 0->1
if (!RANGE_CHECK(Wgg, Wgd, Wmg, Wme, Wmd, Wed, Wee, scale)) {
berr = BW_WEIGHTS_RANGE_ERROR;
goto out;
}
if (do_balance) {
// Wgg*G + Wgd*D == Wee*E + Wed*D, already scaled
if (!CHECK_EQ(Wgg*G + Wgd*D, Wee*E + Wed*D, (margin*T)/3)) {
berr = BW_WEIGHTS_BALANCE_EG_ERROR;
goto out;
}
// Wgg*G + Wgd*D == M*scale + Wmd*D + Wme*E + Wmg*G, already scaled
if (!CHECK_EQ(Wgg*G + Wgd*D, M*scale + Wmd*D + Wme*E + Wmg*G,
(margin*T)/3)) {
berr = BW_WEIGHTS_BALANCE_MID_ERROR;
goto out;
}
}
out:
if (berr) {
log_info(LD_DIR,
"Bw weight mismatch %d. G="I64_FORMAT" M="I64_FORMAT
" E="I64_FORMAT" D="I64_FORMAT" T="I64_FORMAT
" Wmd=%d Wme=%d Wmg=%d Wed=%d Wee=%d"
" Wgd=%d Wgg=%d Wme=%d Wmg=%d",
berr,
I64_PRINTF_ARG(G), I64_PRINTF_ARG(M), I64_PRINTF_ARG(E),
I64_PRINTF_ARG(D), I64_PRINTF_ARG(T),
(int)Wmd, (int)Wme, (int)Wmg, (int)Wed, (int)Wee,
(int)Wgd, (int)Wgg, (int)Wme, (int)Wmg);
}
return berr;
}
/**
* This function computes the bandwidth weights for consensus method 10.
*
* It returns true if weights could be computed, false otherwise.
*/
int
networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G,
int64_t M, int64_t E, int64_t D,
int64_t T, int64_t weight_scale)
{
bw_weights_error_t berr = 0;
int64_t Wgg = -1, Wgd = -1;
int64_t Wmg = -1, Wme = -1, Wmd = -1;
int64_t Wed = -1, Wee = -1;
const char *casename;
if (G <= 0 || M <= 0 || E <= 0 || D <= 0) {
log_warn(LD_DIR, "Consensus with empty bandwidth: "
"G="I64_FORMAT" M="I64_FORMAT" E="I64_FORMAT
" D="I64_FORMAT" T="I64_FORMAT,
I64_PRINTF_ARG(G), I64_PRINTF_ARG(M), I64_PRINTF_ARG(E),
I64_PRINTF_ARG(D), I64_PRINTF_ARG(T));
return 0;
}
/*
* Computed from cases in 3.8.3 of dir-spec.txt
*
* 1. Neither are scarce
* 2. Both Guard and Exit are scarce
* a. R+D <= S
* b. R+D > S
* 3. One of Guard or Exit is scarce
* a. S+D < T/3
* b. S+D >= T/3
*/
if (3*E >= T && 3*G >= T) { // E >= T/3 && G >= T/3
/* Case 1: Neither are scarce. */
casename = "Case 1 (Wgd=Wmd=Wed)";
Wgd = weight_scale/3;
Wed = weight_scale/3;
Wmd = weight_scale/3;
Wee = (weight_scale*(E+G+M))/(3*E);
Wme = weight_scale - Wee;
Wmg = (weight_scale*(2*G-E-M))/(3*G);
Wgg = weight_scale - Wmg;
berr = networkstatus_check_weights(Wgg, Wgd, Wmg, Wme, Wmd, Wee, Wed,
weight_scale, G, M, E, D, T, 10, 1);
if (berr) {
log_warn(LD_DIR,
"Bw Weights error %d for %s v10. G="I64_FORMAT" M="I64_FORMAT
" E="I64_FORMAT" D="I64_FORMAT" T="I64_FORMAT
" Wmd=%d Wme=%d Wmg=%d Wed=%d Wee=%d"
" Wgd=%d Wgg=%d Wme=%d Wmg=%d weight_scale=%d",
berr, casename,
I64_PRINTF_ARG(G), I64_PRINTF_ARG(M), I64_PRINTF_ARG(E),
I64_PRINTF_ARG(D), I64_PRINTF_ARG(T),
(int)Wmd, (int)Wme, (int)Wmg, (int)Wed, (int)Wee,
(int)Wgd, (int)Wgg, (int)Wme, (int)Wmg, (int)weight_scale);
return 0;
}
} else if (3*E < T && 3*G < T) { // E < T/3 && G < T/3
int64_t R = MIN(E, G);
int64_t S = MAX(E, G);
/*
* Case 2: Both Guards and Exits are scarce
* Balance D between E and G, depending upon
* D capacity and scarcity.
*/
if (R+D < S) { // Subcase a
Wgg = weight_scale;