diff --git a/doc/spec/dir-spec.txt b/doc/spec/dir-spec.txt index cd47eb0298..dc97163349 100644 --- a/doc/spec/dir-spec.txt +++ b/doc/spec/dir-spec.txt @@ -1390,6 +1390,23 @@ $Id$ The most recent v3 consensus should be available at: http:///tor/status-vote/current/consensus.z + Starting with Tor version 0.2.1.1-alpha is also available at: + http:///tor/status-vote/current/consensus/++.z + + Where F1, F2, etc. are authority identity fingerprints the client trusts. + Servers will only return a consensus if more than half of the requested + authorities have signed the document, otherwise a 404 error will be sent + back. The fingerprints can be shortened to a length of any multiple of + two, using only the leftmost part of the encoded fingerprint. Tor uses + 3 bytes (6 hex characters) of the fingerprint. + + Clients SHOULD sort the fingerprints in ascending order. Server MUST + accept any order. + + Clients SHOULD use this format when requesting consensus documents from + directory authority servers and from caches running a version of Tor + that is known to support this URL format. + A concatenated set of all the current key certificates should be available at: http:///tor/keys/all.z diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index f879f13cab..2ac6ac3182 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -2924,6 +2924,7 @@ launch_direct_bridge_descriptor_fetch(char *address, bridge_info_t *bridge) return; /* it's already on the way */ directory_initiate_command(address, bridge->addr, bridge->port, 0, + 0, /* does not matter */ 1, bridge->identity, DIR_PURPOSE_FETCH_SERVERDESC, ROUTER_PURPOSE_BRIDGE, diff --git a/src/or/directory.c b/src/or/directory.c index f994a448d8..fd2e215df9 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -37,6 +37,7 @@ const char directory_c_id[] = static void directory_send_command(dir_connection_t *conn, int purpose, int direct, const char *resource, const char *payload, size_t payload_len, + int supports_conditional_consensus, time_t if_modified_since); static int directory_handle_command(dir_connection_t *conn); static int body_is_plausible(const char *body, size_t body_len, int purpose); @@ -57,6 +58,7 @@ static void dir_routerdesc_download_failed(smartlist_t *failed, int was_extrainfo, int was_descriptor_digests); static void note_request(const char *key, size_t bytes); +static int client_likes_consensus(networkstatus_t *v, const char *want_url); /********* START VARIABLES **********/ @@ -338,10 +340,13 @@ directory_get_from_dirserver(uint8_t dir_purpose, uint8_t router_purpose, /* want to ask a running bridge for which we have a descriptor. */ /* XXX021 we assume that all of our bridges can answer any * possible directory question. This won't be true forever. -RD */ + /* It certainly is not true with conditional consensus downloading, + * so, for now, never assume the server supports that. */ routerinfo_t *ri = choose_random_entry(NULL); if (ri) { directory_initiate_command(ri->address, ri->addr, ri->or_port, 0, + 0, /* don't use conditional consensus url */ 1, ri->cache_info.identity_digest, dir_purpose, router_purpose, @@ -463,6 +468,7 @@ directory_initiate_command_routerstatus(routerstatus_t *status, } directory_initiate_command(address, status->addr, status->or_port, status->dir_port, + status->version_supports_conditional_consensus, status->version_supports_begindir, status->identity_digest, dir_purpose, router_purpose, @@ -644,6 +650,7 @@ directory_command_should_use_begindir(or_options_t *options, uint32_t addr, void directory_initiate_command(const char *address, uint32_t addr, uint16_t or_port, uint16_t dir_port, + int supports_conditional_consensus, int supports_begindir, const char *digest, uint8_t dir_purpose, uint8_t router_purpose, int anonymized_connection, const char *resource, @@ -706,7 +713,9 @@ directory_initiate_command(const char *address, uint32_t addr, case 0: /* queue the command on the outbuf */ directory_send_command(conn, dir_purpose, 1, resource, - payload, payload_len, if_modified_since); + payload, payload_len, + supports_conditional_consensus, + if_modified_since); connection_watch_events(TO_CONN(conn), EV_READ | EV_WRITE); /* writable indicates finish, readable indicates broken link, error indicates broken link in windowsland. */ @@ -743,7 +752,9 @@ directory_initiate_command(const char *address, uint32_t addr, conn->_base.state = DIR_CONN_STATE_CLIENT_SENDING; /* queue the command on the outbuf */ directory_send_command(conn, dir_purpose, 0, resource, - payload, payload_len, if_modified_since); + payload, payload_len, + supports_conditional_consensus, + if_modified_since); connection_watch_events(TO_CONN(conn), EV_READ | EV_WRITE); connection_start_reading(TO_CONN(linked_conn)); } @@ -762,6 +773,63 @@ connection_dir_is_encrypted(dir_connection_t *conn) return TO_CONN(conn)->linked; } +/** Helper for sorting + * + * sort strings alphabetically + */ +static int +_compare_strs(const void **a, const void **b) +{ + const char *s1 = *a, *s2 = *b; + return strcmp(s1, s2); +} + +/** Return the URL we should use for a consensus download. + * + * This url depends on whether or not the server we go to + * is sufficiently new to support conditional consensus downloading, + * i.e. GET .../consensus/fpr+fpr+fpr + */ +#define CONDITIONAL_CONSENSUS_FPR_LEN 3 +#if (CONDITIONAL_CONSENSUS_FPR_LEN > DIGEST_LEN) +#error "conditional consensus fingerprint length is larger than digest length +#endif +static char * +directory_get_consensus_url(int supports_conditional_consensus) +{ + char *url; + int len; + + if (supports_conditional_consensus) { + char *authority_id_list; + smartlist_t *authority_digets = smartlist_create(); + + SMARTLIST_FOREACH(router_get_trusted_dir_servers(), + trusted_dir_server_t *, ds, + { + char *hex = tor_malloc(2*CONDITIONAL_CONSENSUS_FPR_LEN+1); + base16_encode(hex, 2*CONDITIONAL_CONSENSUS_FPR_LEN+1, + ds->digest, CONDITIONAL_CONSENSUS_FPR_LEN); + smartlist_add(authority_digets, hex); + }); + smartlist_sort(authority_digets, _compare_strs); + authority_id_list = smartlist_join_strings(authority_digets, + "+", 0, NULL); + + len = strlen(authority_id_list)+64; + url = tor_malloc(len); + tor_snprintf(url, len, "/tor/status-vote/current/consensus/%s.z", + authority_id_list); + + SMARTLIST_FOREACH(authority_digets, char *, cp, tor_free(cp)); + smartlist_free(authority_digets); + tor_free(authority_id_list); + } else { + url = tor_strdup("/tor/status-vote/current/consensus.z"); + } + return url; +} + /** Queue an appropriate HTTP command on conn-\>outbuf. The other args * are as in directory_initiate_command. */ @@ -769,6 +837,7 @@ static void directory_send_command(dir_connection_t *conn, int purpose, int direct, const char *resource, const char *payload, size_t payload_len, + int supports_conditional_consensus, time_t if_modified_since) { char proxystring[256]; @@ -851,7 +920,10 @@ directory_send_command(dir_connection_t *conn, tor_assert(!resource); tor_assert(!payload); httpcommand = "GET"; - url = tor_strdup("/tor/status-vote/current/consensus.z"); + url = directory_get_consensus_url(supports_conditional_consensus); + /* XXX021: downgrade/remove once done with conditional consensus fu */ + log_notice(LD_DIR, "Downloading consensus from %s using %s", + hoststring, url); break; case DIR_PURPOSE_FETCH_CERTIFICATE: tor_assert(resource); @@ -2164,6 +2236,58 @@ directory_dump_request_log(void) } #endif +/** Decide whether a client would accept the consensus we have + * + * Clients can say they only want a consensus if it's signed by more + * than half the authorities in a list. They pass this list in + * the url as "...consensus/fpr+fpr+fpr". + * + * fpr may be an abbreviated fingerprint, i.e. only a left substring + * of the full authority identity digest. (Only strings of even length, + * i.e. encodings of full bytes, are handled correctly. In the case + * of an odd number of hex digits the last one is silently ignored.) + * + * Returns 1 if more than half of the requested authorities signed the + * consensus, 0 otherwise. + */ +int +client_likes_consensus(networkstatus_t *v, const char *want_url) +{ + smartlist_t *want_authorities = smartlist_create(); + int need_at_least; + int have = 0; + + dir_split_resource_into_fingerprints(want_url, want_authorities, NULL, 0, 0); + need_at_least = smartlist_len(want_authorities)/2+1; + SMARTLIST_FOREACH(want_authorities, const char *, d, { + char want_digest[DIGEST_LEN]; + int want_len = strlen(d)/2; + if (want_len > DIGEST_LEN) + want_len = DIGEST_LEN; + + if (base16_decode(want_digest, DIGEST_LEN, d, want_len*2) < 0) { + log_warn(LD_DIR,"Failed to decode requested authority digest %s.", d); + continue; + }; + + SMARTLIST_FOREACH(v->voters, networkstatus_voter_info_t *, vi, { + if (vi->signature && + !memcmp(vi->identity_digest, want_digest, want_len)) { + have++; + break; + }; + }); + + /* early exit, if we already have enough */ + if (have >= need_at_least) + break; + }); + + SMARTLIST_FOREACH(want_authorities, char *, d, tor_free(d)); + smartlist_free(want_authorities); + return (have >= need_at_least); +} + /** Helper function: called when a dirserver gets a complete HTTP GET * request. Look for a request for a directory or for a rendezvous * service descriptor. On finding one, write a response into @@ -2291,7 +2415,7 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers, } if (!strcmpstart(url,"/tor/status/") - || !strcmp(url, "/tor/status-vote/current/consensus")) { + || !strcmpstart(url, "/tor/status-vote/current/consensus")) { /* v2 or v3 network status fetch. */ smartlist_t *dir_fps = smartlist_create(); int is_v3 = !strcmpstart(url, "/tor/status-vote"); @@ -2312,6 +2436,15 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers, } else { networkstatus_t *v = networkstatus_get_latest_consensus(); time_t now = time(NULL); + #define CONSENSUS_URL_PREFIX "/tor/status-vote/current/consensus/" + if (!strcmpstart(url, CONSENSUS_URL_PREFIX) && + !client_likes_consensus(v, url + strlen(CONSENSUS_URL_PREFIX))) { + write_http_status_line(conn, 404, "Consensus not signed by sufficient " + "number of requested authorities"); + smartlist_free(dir_fps); + goto done; + } + smartlist_add(dir_fps, tor_memdup("\0\0\0\0\0\0\0\0\0\0" "\0\0\0\0\0\0\0\0\0\0", 20)); request_type = compressed?"v3.z":"v3"; diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c index 5ec72daf40..f56ffff19e 100644 --- a/src/or/networkstatus.c +++ b/src/or/networkstatus.c @@ -1280,6 +1280,8 @@ routerstatus_has_changed(const routerstatus_t *a, const routerstatus_t *b) a->version_supports_begindir != b->version_supports_begindir || a->version_supports_extrainfo_upload != b->version_supports_extrainfo_upload || + a->version_supports_conditional_consensus != + b->version_supports_conditional_consensus || a->version_supports_v3_dir != b->version_supports_v3_dir; } diff --git a/src/or/or.h b/src/or/or.h index 8c25064215..592cef764a 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -1369,6 +1369,9 @@ typedef struct routerstatus_t { unsigned int version_known:1; /** True iff this router is a version that supports BEGIN_DIR cells. */ unsigned int version_supports_begindir:1; + /** True iff this router is a version that supports conditional consensus + * downloads (signed by list of authorities). */ + unsigned int version_supports_conditional_consensus:1; /** True iff this router is a version that we can post extrainfo docs to. */ unsigned int version_supports_extrainfo_upload:1; /** True iff this router is a version that, if it caches directory info, @@ -3048,6 +3051,7 @@ int connection_dir_finished_connecting(dir_connection_t *conn); void connection_dir_request_failed(dir_connection_t *conn); void directory_initiate_command(const char *address, uint32_t addr, uint16_t or_port, uint16_t dir_port, + int supports_conditional_consensus, int supports_begindir, const char *digest, uint8_t dir_purpose, uint8_t router_purpose, int anonymized_connection, diff --git a/src/or/router.c b/src/or/router.c index 91518141cf..84c05fdf69 100644 --- a/src/or/router.c +++ b/src/or/router.c @@ -726,6 +726,7 @@ consider_testing_reachability(int test_or, int test_dir) /* ask myself, via tor, for my server descriptor. */ directory_initiate_command(me->address, me->addr, me->or_port, me->dir_port, + 0, /* does not matter */ 0, me->cache_info.identity_digest, DIR_PURPOSE_FETCH_SERVERDESC, ROUTER_PURPOSE_GENERAL, diff --git a/src/or/routerlist.c b/src/or/routerlist.c index 994d019f56..e909e6165f 100644 --- a/src/or/routerlist.c +++ b/src/or/routerlist.c @@ -3512,6 +3512,7 @@ add_trusted_dir_server(const char *nickname, const char *address, if (ent->or_port) ent->fake_status.version_supports_begindir = 1; + ent->fake_status.version_supports_conditional_consensus = 1; smartlist_add(trusted_dir_servers, ent); router_dir_info_changed(); diff --git a/src/or/routerparse.c b/src/or/routerparse.c index 7ff6c63112..016b938ae9 100644 --- a/src/or/routerparse.c +++ b/src/or/routerparse.c @@ -1828,6 +1828,7 @@ routerstatus_parse_entry_from_string(memarea_t *area, if (strcmpstart(tok->args[0], "Tor ")) { rs->version_supports_begindir = 1; rs->version_supports_extrainfo_upload = 1; + rs->version_supports_conditional_consensus = 1; } else { rs->version_supports_begindir = tor_version_as_new_as(tok->args[0], "0.2.0.1-alpha"); @@ -1835,6 +1836,8 @@ routerstatus_parse_entry_from_string(memarea_t *area, tor_version_as_new_as(tok->args[0], "0.2.0.0-alpha-dev (r10070)"); rs->version_supports_v3_dir = tor_version_as_new_as(tok->args[0], "0.2.0.8-alpha"); + rs->version_supports_conditional_consensus = + tor_version_as_new_as(tok->args[0], "0.2.1.1-alpha"); } if (vote_rs) { vote_rs->version = tor_strdup(tok->args[0]);