diff options
Diffstat (limited to 'src/or/dirvote.c')
| -rw-r--r-- | src/or/dirvote.c | 99 |
1 files changed, 76 insertions, 23 deletions
diff --git a/src/or/dirvote.c b/src/or/dirvote.c index 738ab35bc1..e92d3b49dc 100644 --- a/src/or/dirvote.c +++ b/src/or/dirvote.c @@ -26,6 +26,39 @@ /** * \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 @@ -250,11 +283,11 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key, smartlist_add(chunks, rsf); for (h = vrs->microdesc; h; h = h->next) { - smartlist_add(chunks, tor_strdup(h->microdesc_hash_line)); + smartlist_add_strdup(chunks, h->microdesc_hash_line); } } SMARTLIST_FOREACH_END(vrs); - smartlist_add(chunks, tor_strdup("directory-footer\n")); + smartlist_add_strdup(chunks, "directory-footer\n"); /* The digest includes everything up through the space after * directory-signature. (Yuck.) */ @@ -894,7 +927,7 @@ networkstatus_check_weights(int64_t Wgg, int64_t Wgd, int64_t Wmg, * * It returns true if weights could be computed, false otherwise. */ -static int +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) @@ -976,7 +1009,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G, Wgd = weight_scale; } } else { // Subcase b: R+D >= S - casename = "Case 2b1 (Wgg=1, Wmd=Wgd)"; + casename = "Case 2b1 (Wgg=weight_scale, Wmd=Wgd)"; Wee = (weight_scale*(E - G + M))/E; Wed = (weight_scale*(D - 2*E + 4*G - 2*M))/(3*D); Wme = (weight_scale*(G-M))/E; @@ -989,7 +1022,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G, weight_scale, G, M, E, D, T, 10, 1); if (berr) { - casename = "Case 2b2 (Wgg=1, Wee=1)"; + casename = "Case 2b2 (Wgg=weight_scale, Wee=weight_scale)"; Wgg = weight_scale; Wee = weight_scale; Wed = (weight_scale*(D - 2*E + G + M))/(3*D); @@ -1058,7 +1091,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G, } else { // Subcase b: S+D >= T/3 // D != 0 because S+D >= T/3 if (G < E) { - casename = "Case 3bg (G scarce, Wgg=1, Wmd == Wed)"; + casename = "Case 3bg (G scarce, Wgg=weight_scale, Wmd == Wed)"; Wgg = weight_scale; Wgd = (weight_scale*(D - 2*G + E + M))/(3*D); Wmg = 0; @@ -1070,7 +1103,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G, berr = networkstatus_check_weights(Wgg, Wgd, Wmg, Wme, Wmd, Wee, Wed, weight_scale, G, M, E, D, T, 10, 1); } else { // G >= E - casename = "Case 3be (E scarce, Wee=1, Wmd == Wgd)"; + casename = "Case 3be (E scarce, Wee=weight_scale, Wmd == Wgd)"; Wee = weight_scale; Wed = (weight_scale*(D - 2*E + G + M))/(3*D); Wme = 0; @@ -1104,7 +1137,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G, tor_assert(0 < weight_scale && weight_scale <= INT32_MAX); /* - * Provide Wgm=Wgg, Wmm=1, Wem=Wee, Weg=Wed. May later determine + * Provide Wgm=Wgg, Wmm=weight_scale, Wem=Wee, Weg=Wed. May later determine * that middle nodes need different bandwidth weights for dirport traffic, * or that weird exit policies need special weight, or that bridges * need special weight. @@ -1287,7 +1320,17 @@ compute_nth_protocol_set(int n, int n_voters, const smartlist_t *votes) * value in a newly allocated string. * * Note: this function DOES NOT check whether the votes are from - * recognized authorities. (dirvote_add_vote does that.) */ + * recognized authorities. (dirvote_add_vote does that.) + * + * <strong>WATCH OUT</strong>: You need to think before you change the + * behavior of this function, or of the functions it calls! If some + * authorities compute the consensus with a different algorithm than + * others, they will not reach the same result, and they will not all + * sign the same thing! If you really need to change the algorithm + * here, you should allocate a new "consensus_method" for the new + * behavior, and make the new behavior conditional on a new-enough + * consensus_method. + **/ char * networkstatus_compute_consensus(smartlist_t *votes, int total_authorities, @@ -1306,7 +1349,7 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_t *flags; const char *flavor_name; uint32_t max_unmeasured_bw_kb = DEFAULT_MAX_UNMEASURED_BW_KB; - int64_t G=0, M=0, E=0, D=0, T=0; /* For bandwidth weights */ + int64_t G, M, E, D, T; /* For bandwidth weights */ const routerstatus_format_type_t rs_format = flavor == FLAV_NS ? NS_V3_CONSENSUS : NS_V3_CONSENSUS_MICRODESC; char *params = NULL; @@ -1338,6 +1381,16 @@ networkstatus_compute_consensus(smartlist_t *votes, consensus_method = MAX_SUPPORTED_CONSENSUS_METHOD; } + if (consensus_method >= MIN_METHOD_FOR_INIT_BW_WEIGHTS_ONE) { + /* It's smarter to initialize these weights to 1, so that later on, + * we can't accidentally divide by zero. */ + G = M = E = D = 1; + T = 4; + } else { + /* ...but originally, they were set to zero. */ + G = M = E = D = T = 0; + } + /* Compute medians of time-related things, and figure out how many * routers we might need to talk about. */ { @@ -1377,7 +1430,7 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_free(sv); /* elements get freed later. */ } SMARTLIST_FOREACH(v->known_flags, const char *, cp, - smartlist_add(flags, tor_strdup(cp))); + smartlist_add_strdup(flags, cp)); } SMARTLIST_FOREACH_END(v); valid_after = median_time(va_times, n_votes); fresh_until = median_time(fu_times, n_votes); @@ -1410,7 +1463,7 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_free(combined_client_versions); if (consensus_method >= MIN_METHOD_FOR_ED25519_ID_VOTING) - smartlist_add(flags, tor_strdup("NoEdConsensus")); + smartlist_add_strdup(flags, "NoEdConsensus"); smartlist_sort_strings(flags); smartlist_uniq_strings(flags); @@ -1474,9 +1527,9 @@ networkstatus_compute_consensus(smartlist_t *votes, total_authorities); if (smartlist_len(param_list)) { params = smartlist_join_strings(param_list, " ", 0, NULL); - smartlist_add(chunks, tor_strdup("params ")); + smartlist_add_strdup(chunks, "params "); smartlist_add(chunks, params); - smartlist_add(chunks, tor_strdup("\n")); + smartlist_add_strdup(chunks, "\n"); } if (consensus_method >= MIN_METHOD_FOR_SHARED_RANDOM) { @@ -2063,10 +2116,10 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_join_strings(chosen_flags, " ", 0, NULL)); /* Now the version line. */ if (chosen_version) { - smartlist_add(chunks, tor_strdup("\nv ")); - smartlist_add(chunks, tor_strdup(chosen_version)); + smartlist_add_strdup(chunks, "\nv "); + smartlist_add_strdup(chunks, chosen_version); } - smartlist_add(chunks, tor_strdup("\n")); + smartlist_add_strdup(chunks, "\n"); if (chosen_protocol_list && consensus_method >= MIN_METHOD_FOR_RS_PROTOCOLS) { smartlist_add_asprintf(chunks, "pr %s\n", chosen_protocol_list); @@ -2119,7 +2172,7 @@ networkstatus_compute_consensus(smartlist_t *votes, } /* Mark the directory footer region */ - smartlist_add(chunks, tor_strdup("directory-footer\n")); + smartlist_add_strdup(chunks, "directory-footer\n"); { int64_t weight_scale = BW_WEIGHT_SCALE; @@ -2170,7 +2223,7 @@ networkstatus_compute_consensus(smartlist_t *votes, const char *algname = crypto_digest_algorithm_get_name(digest_alg); char *signature; - smartlist_add(chunks, tor_strdup("directory-signature ")); + smartlist_add_strdup(chunks, "directory-signature "); /* Compute the hash of the chunks. */ crypto_digest_smartlist(digest, digest_len, chunks, "", digest_alg); @@ -2197,7 +2250,7 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_add(chunks, signature); if (legacy_id_key_digest && legacy_signing_key) { - smartlist_add(chunks, tor_strdup("directory-signature ")); + smartlist_add_strdup(chunks, "directory-signature "); base16_encode(fingerprint, sizeof(fingerprint), legacy_id_key_digest, DIGEST_LEN); crypto_pk_get_fingerprint(legacy_signing_key, @@ -2510,7 +2563,7 @@ networkstatus_format_signatures(networkstatus_t *consensus, base64_encode(buf, sizeof(buf), sig->signature, sig->signature_len, BASE64_ENCODE_MULTILINE); strlcat(buf, "-----END SIGNATURE-----\n", sizeof(buf)); - smartlist_add(elements, tor_strdup(buf)); + smartlist_add_strdup(elements, buf); } SMARTLIST_FOREACH_END(sig); } SMARTLIST_FOREACH_END(v); @@ -3620,8 +3673,8 @@ dirvote_add_signatures(const char *detached_signatures_body, "Queuing it for the next consensus.", source); if (!pending_consensus_signature_list) pending_consensus_signature_list = smartlist_new(); - smartlist_add(pending_consensus_signature_list, - tor_strdup(detached_signatures_body)); + smartlist_add_strdup(pending_consensus_signature_list, + detached_signatures_body); *msg = "Signature queued"; return 0; } |