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- /* Copyright (c) 2001 Matej Pfajfar.
- * Copyright (c) 2001-2004, Roger Dingledine.
- * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2018, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file node_select.c
- * \brief Code to choose nodes randomly based on restrictions and
- * weighted probabilities.
- **/
- #define NODE_SELECT_PRIVATE
- #include "core/or/or.h"
- #include "app/config/config.h"
- #include "core/mainloop/connection.h"
- #include "core/or/policies.h"
- #include "core/or/reasons.h"
- #include "feature/client/entrynodes.h"
- #include "feature/dircommon/directory.h"
- #include "feature/dirclient/dirclient.h"
- #include "feature/nodelist/dirlist.h"
- #include "feature/nodelist/microdesc.h"
- #include "feature/nodelist/networkstatus.h"
- #include "feature/nodelist/node_select.h"
- #include "feature/nodelist/nodelist.h"
- #include "feature/nodelist/routerlist.h"
- #include "feature/nodelist/routerset.h"
- #include "feature/relay/router.h"
- #include "lib/crypt_ops/crypto_rand.h"
- #include "lib/math/fp.h"
- #include "feature/dirclient/dir_server_st.h"
- #include "feature/nodelist/networkstatus_st.h"
- #include "feature/nodelist/node_st.h"
- #include "feature/nodelist/routerinfo_st.h"
- #include "feature/nodelist/routerstatus_st.h"
- static int compute_weighted_bandwidths(const smartlist_t *sl,
- bandwidth_weight_rule_t rule,
- double **bandwidths_out,
- double *total_bandwidth_out);
- static const routerstatus_t *router_pick_trusteddirserver_impl(
- const smartlist_t *sourcelist, dirinfo_type_t auth,
- int flags, int *n_busy_out);
- static const routerstatus_t *router_pick_dirserver_generic(
- smartlist_t *sourcelist,
- dirinfo_type_t type, int flags);
- /** Try to find a running dirserver that supports operations of <b>type</b>.
- *
- * If there are no running dirservers in our routerlist and the
- * <b>PDS_RETRY_IF_NO_SERVERS</b> flag is set, set all the fallback ones
- * (including authorities) as running again, and pick one.
- *
- * If the <b>PDS_IGNORE_FASCISTFIREWALL</b> flag is set, then include
- * dirservers that we can't reach.
- *
- * If the <b>PDS_ALLOW_SELF</b> flag is not set, then don't include ourself
- * (if we're a dirserver).
- *
- * Don't pick a fallback directory mirror if any non-fallback is viable;
- * (the fallback directory mirrors include the authorities)
- * try to avoid using servers that have returned 503 recently.
- */
- const routerstatus_t *
- router_pick_directory_server(dirinfo_type_t type, int flags)
- {
- int busy = 0;
- const routerstatus_t *choice;
- choice = router_pick_directory_server_impl(type, flags, &busy);
- if (choice || !(flags & PDS_RETRY_IF_NO_SERVERS))
- return choice;
- if (busy) {
- /* If the reason that we got no server is that servers are "busy",
- * we must be excluding good servers because we already have serverdesc
- * fetches with them. Do not mark down servers up because of this. */
- tor_assert((flags & (PDS_NO_EXISTING_SERVERDESC_FETCH|
- PDS_NO_EXISTING_MICRODESC_FETCH)));
- return NULL;
- }
- log_info(LD_DIR,
- "No reachable router entries for dirservers. "
- "Trying them all again.");
- /* mark all fallback directory mirrors as up again */
- router_reset_status_download_failures();
- /* try again */
- choice = router_pick_directory_server_impl(type, flags, NULL);
- return choice;
- }
- /** Try to find a running fallback directory. Flags are as for
- * router_pick_directory_server.
- */
- const routerstatus_t *
- router_pick_dirserver_generic(smartlist_t *sourcelist,
- dirinfo_type_t type, int flags)
- {
- const routerstatus_t *choice;
- int busy = 0;
- if (smartlist_len(sourcelist) == 1) {
- /* If there's only one choice, then we should disable the logic that
- * would otherwise prevent us from choosing ourself. */
- flags |= PDS_ALLOW_SELF;
- }
- choice = router_pick_trusteddirserver_impl(sourcelist, type, flags, &busy);
- if (choice || !(flags & PDS_RETRY_IF_NO_SERVERS))
- return choice;
- if (busy) {
- /* If the reason that we got no server is that servers are "busy",
- * we must be excluding good servers because we already have serverdesc
- * fetches with them. Do not mark down servers up because of this. */
- tor_assert((flags & (PDS_NO_EXISTING_SERVERDESC_FETCH|
- PDS_NO_EXISTING_MICRODESC_FETCH)));
- return NULL;
- }
- log_info(LD_DIR,
- "No dirservers are reachable. Trying them all again.");
- mark_all_dirservers_up(sourcelist);
- return router_pick_trusteddirserver_impl(sourcelist, type, flags, NULL);
- }
- /* Common retry code for router_pick_directory_server_impl and
- * router_pick_trusteddirserver_impl. Retry with the non-preferred IP version.
- * Must be called before RETRY_WITHOUT_EXCLUDE().
- *
- * If we got no result, and we are applying IP preferences, and we are a
- * client that could use an alternate IP version, try again with the
- * opposite preferences. */
- #define RETRY_ALTERNATE_IP_VERSION(retry_label) \
- STMT_BEGIN \
- if (result == NULL && try_ip_pref && options->ClientUseIPv4 \
- && fascist_firewall_use_ipv6(options) && !server_mode(options) \
- && !n_busy) { \
- n_excluded = 0; \
- n_busy = 0; \
- try_ip_pref = 0; \
- goto retry_label; \
- } \
- STMT_END \
- /* Common retry code for router_pick_directory_server_impl and
- * router_pick_trusteddirserver_impl. Retry without excluding nodes, but with
- * the preferred IP version. Must be called after RETRY_ALTERNATE_IP_VERSION().
- *
- * If we got no result, and we are excluding nodes, and StrictNodes is
- * not set, try again without excluding nodes. */
- #define RETRY_WITHOUT_EXCLUDE(retry_label) \
- STMT_BEGIN \
- if (result == NULL && try_excluding && !options->StrictNodes \
- && n_excluded && !n_busy) { \
- try_excluding = 0; \
- n_excluded = 0; \
- n_busy = 0; \
- try_ip_pref = 1; \
- goto retry_label; \
- } \
- STMT_END
- /* Common code used in the loop within router_pick_directory_server_impl and
- * router_pick_trusteddirserver_impl.
- *
- * Check if the given <b>identity</b> supports extrainfo. If not, skip further
- * checks.
- */
- #define SKIP_MISSING_TRUSTED_EXTRAINFO(type, identity) \
- STMT_BEGIN \
- int is_trusted_extrainfo = router_digest_is_trusted_dir_type( \
- (identity), EXTRAINFO_DIRINFO); \
- if (((type) & EXTRAINFO_DIRINFO) && \
- !router_supports_extrainfo((identity), is_trusted_extrainfo)) \
- continue; \
- STMT_END
- #ifndef LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
- #define LOG_FALSE_POSITIVES_DURING_BOOTSTRAP 0
- #endif
- /* Log a message if rs is not found or not a preferred address */
- static void
- router_picked_poor_directory_log(const routerstatus_t *rs)
- {
- const networkstatus_t *usable_consensus;
- usable_consensus = networkstatus_get_reasonably_live_consensus(time(NULL),
- usable_consensus_flavor());
- #if !LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
- /* Don't log early in the bootstrap process, it's normal to pick from a
- * small pool of nodes. Of course, this won't help if we're trying to
- * diagnose bootstrap issues. */
- if (!smartlist_len(nodelist_get_list()) || !usable_consensus
- || !router_have_minimum_dir_info()) {
- return;
- }
- #endif /* !LOG_FALSE_POSITIVES_DURING_BOOTSTRAP */
- /* We couldn't find a node, or the one we have doesn't fit our preferences.
- * Sometimes this is normal, sometimes it can be a reachability issue. */
- if (!rs) {
- /* This happens a lot, so it's at debug level */
- log_debug(LD_DIR, "Wanted to make an outgoing directory connection, but "
- "we couldn't find a directory that fit our criteria. "
- "Perhaps we will succeed next time with less strict criteria.");
- } else if (!fascist_firewall_allows_rs(rs, FIREWALL_OR_CONNECTION, 1)
- && !fascist_firewall_allows_rs(rs, FIREWALL_DIR_CONNECTION, 1)
- ) {
- /* This is rare, and might be interesting to users trying to diagnose
- * connection issues on dual-stack machines. */
- log_info(LD_DIR, "Selected a directory %s with non-preferred OR and Dir "
- "addresses for launching an outgoing connection: "
- "IPv4 %s OR %d Dir %d IPv6 %s OR %d Dir %d",
- routerstatus_describe(rs),
- fmt_addr32(rs->addr), rs->or_port,
- rs->dir_port, fmt_addr(&rs->ipv6_addr),
- rs->ipv6_orport, rs->dir_port);
- }
- }
- #undef LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
- /* Check if we already have a directory fetch from ap, for serverdesc
- * (including extrainfo) or microdesc documents.
- * If so, return 1, if not, return 0.
- * Also returns 0 if addr is NULL, tor_addr_is_null(addr), or dir_port is 0.
- */
- STATIC int
- router_is_already_dir_fetching(const tor_addr_port_t *ap, int serverdesc,
- int microdesc)
- {
- if (!ap || tor_addr_is_null(&ap->addr) || !ap->port) {
- return 0;
- }
- /* XX/teor - we're not checking tunnel connections here, see #17848
- */
- if (serverdesc && (
- connection_get_by_type_addr_port_purpose(
- CONN_TYPE_DIR, &ap->addr, ap->port, DIR_PURPOSE_FETCH_SERVERDESC)
- || connection_get_by_type_addr_port_purpose(
- CONN_TYPE_DIR, &ap->addr, ap->port, DIR_PURPOSE_FETCH_EXTRAINFO))) {
- return 1;
- }
- if (microdesc && (
- connection_get_by_type_addr_port_purpose(
- CONN_TYPE_DIR, &ap->addr, ap->port, DIR_PURPOSE_FETCH_MICRODESC))) {
- return 1;
- }
- return 0;
- }
- /* Check if we already have a directory fetch from the ipv4 or ipv6
- * router, for serverdesc (including extrainfo) or microdesc documents.
- * If so, return 1, if not, return 0.
- */
- static int
- router_is_already_dir_fetching_(uint32_t ipv4_addr,
- const tor_addr_t *ipv6_addr,
- uint16_t dir_port,
- int serverdesc,
- int microdesc)
- {
- tor_addr_port_t ipv4_dir_ap, ipv6_dir_ap;
- /* Assume IPv6 DirPort is the same as IPv4 DirPort */
- tor_addr_from_ipv4h(&ipv4_dir_ap.addr, ipv4_addr);
- ipv4_dir_ap.port = dir_port;
- tor_addr_copy(&ipv6_dir_ap.addr, ipv6_addr);
- ipv6_dir_ap.port = dir_port;
- return (router_is_already_dir_fetching(&ipv4_dir_ap, serverdesc, microdesc)
- || router_is_already_dir_fetching(&ipv6_dir_ap, serverdesc, microdesc));
- }
- /** Pick a random running valid directory server/mirror from our
- * routerlist. Arguments are as for router_pick_directory_server(), except:
- *
- * If <b>n_busy_out</b> is provided, set *<b>n_busy_out</b> to the number of
- * directories that we excluded for no other reason than
- * PDS_NO_EXISTING_SERVERDESC_FETCH or PDS_NO_EXISTING_MICRODESC_FETCH.
- */
- STATIC const routerstatus_t *
- router_pick_directory_server_impl(dirinfo_type_t type, int flags,
- int *n_busy_out)
- {
- const or_options_t *options = get_options();
- const node_t *result;
- smartlist_t *direct, *tunnel;
- smartlist_t *trusted_direct, *trusted_tunnel;
- smartlist_t *overloaded_direct, *overloaded_tunnel;
- time_t now = time(NULL);
- const networkstatus_t *consensus = networkstatus_get_latest_consensus();
- const int requireother = ! (flags & PDS_ALLOW_SELF);
- const int fascistfirewall = ! (flags & PDS_IGNORE_FASCISTFIREWALL);
- const int no_serverdesc_fetching =(flags & PDS_NO_EXISTING_SERVERDESC_FETCH);
- const int no_microdesc_fetching = (flags & PDS_NO_EXISTING_MICRODESC_FETCH);
- int try_excluding = 1, n_excluded = 0, n_busy = 0;
- int try_ip_pref = 1;
- if (!consensus)
- return NULL;
- retry_search:
- direct = smartlist_new();
- tunnel = smartlist_new();
- trusted_direct = smartlist_new();
- trusted_tunnel = smartlist_new();
- overloaded_direct = smartlist_new();
- overloaded_tunnel = smartlist_new();
- const int skip_or_fw = router_skip_or_reachability(options, try_ip_pref);
- const int skip_dir_fw = router_skip_dir_reachability(options, try_ip_pref);
- const int must_have_or = directory_must_use_begindir(options);
- /* Find all the running dirservers we know about. */
- SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), const node_t *, node) {
- int is_trusted;
- int is_overloaded;
- const routerstatus_t *status = node->rs;
- const country_t country = node->country;
- if (!status)
- continue;
- if (!node->is_running || !node_is_dir(node) || !node->is_valid)
- continue;
- if (requireother && router_digest_is_me(node->identity))
- continue;
- SKIP_MISSING_TRUSTED_EXTRAINFO(type, node->identity);
- if (try_excluding &&
- routerset_contains_routerstatus(options->ExcludeNodes, status,
- country)) {
- ++n_excluded;
- continue;
- }
- if (router_is_already_dir_fetching_(status->addr,
- &status->ipv6_addr,
- status->dir_port,
- no_serverdesc_fetching,
- no_microdesc_fetching)) {
- ++n_busy;
- continue;
- }
- is_overloaded = status->last_dir_503_at + DIR_503_TIMEOUT > now;
- is_trusted = router_digest_is_trusted_dir(node->identity);
- /* Clients use IPv6 addresses if the server has one and the client
- * prefers IPv6.
- * Add the router if its preferred address and port are reachable.
- * If we don't get any routers, we'll try again with the non-preferred
- * address for each router (if any). (To ensure correct load-balancing
- * we try routers that only have one address both times.)
- */
- if (!fascistfirewall || skip_or_fw ||
- fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION,
- try_ip_pref))
- smartlist_add(is_trusted ? trusted_tunnel :
- is_overloaded ? overloaded_tunnel : tunnel, (void*)node);
- else if (!must_have_or && (skip_dir_fw ||
- fascist_firewall_allows_node(node, FIREWALL_DIR_CONNECTION,
- try_ip_pref)))
- smartlist_add(is_trusted ? trusted_direct :
- is_overloaded ? overloaded_direct : direct, (void*)node);
- } SMARTLIST_FOREACH_END(node);
- if (smartlist_len(tunnel)) {
- result = node_sl_choose_by_bandwidth(tunnel, WEIGHT_FOR_DIR);
- } else if (smartlist_len(overloaded_tunnel)) {
- result = node_sl_choose_by_bandwidth(overloaded_tunnel,
- WEIGHT_FOR_DIR);
- } else if (smartlist_len(trusted_tunnel)) {
- /* FFFF We don't distinguish between trusteds and overloaded trusteds
- * yet. Maybe one day we should. */
- /* FFFF We also don't load balance over authorities yet. I think this
- * is a feature, but it could easily be a bug. -RD */
- result = smartlist_choose(trusted_tunnel);
- } else if (smartlist_len(direct)) {
- result = node_sl_choose_by_bandwidth(direct, WEIGHT_FOR_DIR);
- } else if (smartlist_len(overloaded_direct)) {
- result = node_sl_choose_by_bandwidth(overloaded_direct,
- WEIGHT_FOR_DIR);
- } else {
- result = smartlist_choose(trusted_direct);
- }
- smartlist_free(direct);
- smartlist_free(tunnel);
- smartlist_free(trusted_direct);
- smartlist_free(trusted_tunnel);
- smartlist_free(overloaded_direct);
- smartlist_free(overloaded_tunnel);
- RETRY_ALTERNATE_IP_VERSION(retry_search);
- RETRY_WITHOUT_EXCLUDE(retry_search);
- if (n_busy_out)
- *n_busy_out = n_busy;
- router_picked_poor_directory_log(result ? result->rs : NULL);
- return result ? result->rs : NULL;
- }
- /** Given an array of double/uint64_t unions that are currently being used as
- * doubles, convert them to uint64_t, and try to scale them linearly so as to
- * much of the range of uint64_t. If <b>total_out</b> is provided, set it to
- * the sum of all elements in the array _before_ scaling. */
- STATIC void
- scale_array_elements_to_u64(uint64_t *entries_out, const double *entries_in,
- int n_entries,
- uint64_t *total_out)
- {
- double total = 0.0;
- double scale_factor = 0.0;
- int i;
- for (i = 0; i < n_entries; ++i)
- total += entries_in[i];
- if (total > 0.0) {
- scale_factor = ((double)INT64_MAX) / total;
- scale_factor /= 4.0; /* make sure we're very far away from overflowing */
- }
- for (i = 0; i < n_entries; ++i)
- entries_out[i] = tor_llround(entries_in[i] * scale_factor);
- if (total_out)
- *total_out = (uint64_t) total;
- }
- /** Pick a random element of <b>n_entries</b>-element array <b>entries</b>,
- * choosing each element with a probability proportional to its (uint64_t)
- * value, and return the index of that element. If all elements are 0, choose
- * an index at random. Return -1 on error.
- */
- STATIC int
- choose_array_element_by_weight(const uint64_t *entries, int n_entries)
- {
- int i;
- uint64_t rand_val;
- uint64_t total = 0;
- for (i = 0; i < n_entries; ++i)
- total += entries[i];
- if (n_entries < 1)
- return -1;
- if (total == 0)
- return crypto_rand_int(n_entries);
- tor_assert(total < INT64_MAX);
- rand_val = crypto_rand_uint64(total);
- return select_array_member_cumulative_timei(
- entries, n_entries, total, rand_val);
- }
- /** Return bw*1000, unless bw*1000 would overflow, in which case return
- * INT32_MAX. */
- static inline int32_t
- kb_to_bytes(uint32_t bw)
- {
- return (bw > (INT32_MAX/1000)) ? INT32_MAX : bw*1000;
- }
- /** Helper function:
- * choose a random element of smartlist <b>sl</b> of nodes, weighted by
- * the advertised bandwidth of each element using the consensus
- * bandwidth weights.
- *
- * If <b>rule</b>==WEIGHT_FOR_EXIT. we're picking an exit node: consider all
- * nodes' bandwidth equally regardless of their Exit status, since there may
- * be some in the list because they exit to obscure ports. If
- * <b>rule</b>==NO_WEIGHTING, we're picking a non-exit node: weight
- * exit-node's bandwidth less depending on the smallness of the fraction of
- * Exit-to-total bandwidth. If <b>rule</b>==WEIGHT_FOR_GUARD, we're picking a
- * guard node: consider all guard's bandwidth equally. Otherwise, weight
- * guards proportionally less.
- */
- static const node_t *
- smartlist_choose_node_by_bandwidth_weights(const smartlist_t *sl,
- bandwidth_weight_rule_t rule)
- {
- double *bandwidths_dbl=NULL;
- uint64_t *bandwidths_u64=NULL;
- if (compute_weighted_bandwidths(sl, rule, &bandwidths_dbl, NULL) < 0)
- return NULL;
- bandwidths_u64 = tor_calloc(smartlist_len(sl), sizeof(uint64_t));
- scale_array_elements_to_u64(bandwidths_u64, bandwidths_dbl,
- smartlist_len(sl), NULL);
- {
- int idx = choose_array_element_by_weight(bandwidths_u64,
- smartlist_len(sl));
- tor_free(bandwidths_dbl);
- tor_free(bandwidths_u64);
- return idx < 0 ? NULL : smartlist_get(sl, idx);
- }
- }
- /** When weighting bridges, enforce these values as lower and upper
- * bound for believable bandwidth, because there is no way for us
- * to verify a bridge's bandwidth currently. */
- #define BRIDGE_MIN_BELIEVABLE_BANDWIDTH 20000 /* 20 kB/sec */
- #define BRIDGE_MAX_BELIEVABLE_BANDWIDTH 100000 /* 100 kB/sec */
- /** Return the smaller of the router's configured BandwidthRate
- * and its advertised capacity, making sure to stay within the
- * interval between bridge-min-believe-bw and
- * bridge-max-believe-bw. */
- static uint32_t
- bridge_get_advertised_bandwidth_bounded(routerinfo_t *router)
- {
- uint32_t result = router->bandwidthcapacity;
- if (result > router->bandwidthrate)
- result = router->bandwidthrate;
- if (result > BRIDGE_MAX_BELIEVABLE_BANDWIDTH)
- result = BRIDGE_MAX_BELIEVABLE_BANDWIDTH;
- else if (result < BRIDGE_MIN_BELIEVABLE_BANDWIDTH)
- result = BRIDGE_MIN_BELIEVABLE_BANDWIDTH;
- return result;
- }
- /** Given a list of routers and a weighting rule as in
- * smartlist_choose_node_by_bandwidth_weights, compute weighted bandwidth
- * values for each node and store them in a freshly allocated
- * *<b>bandwidths_out</b> of the same length as <b>sl</b>, and holding results
- * as doubles. If <b>total_bandwidth_out</b> is non-NULL, set it to the total
- * of all the bandwidths.
- * Return 0 on success, -1 on failure. */
- static int
- compute_weighted_bandwidths(const smartlist_t *sl,
- bandwidth_weight_rule_t rule,
- double **bandwidths_out,
- double *total_bandwidth_out)
- {
- int64_t weight_scale;
- double Wg = -1, Wm = -1, We = -1, Wd = -1;
- double Wgb = -1, Wmb = -1, Web = -1, Wdb = -1;
- guardfraction_bandwidth_t guardfraction_bw;
- double *bandwidths = NULL;
- double total_bandwidth = 0.0;
- tor_assert(sl);
- tor_assert(bandwidths_out);
- /* Can't choose exit and guard at same time */
- tor_assert(rule == NO_WEIGHTING ||
- rule == WEIGHT_FOR_EXIT ||
- rule == WEIGHT_FOR_GUARD ||
- rule == WEIGHT_FOR_MID ||
- rule == WEIGHT_FOR_DIR);
- *bandwidths_out = NULL;
- if (total_bandwidth_out) {
- *total_bandwidth_out = 0.0;
- }
- if (smartlist_len(sl) == 0) {
- log_info(LD_CIRC,
- "Empty routerlist passed in to consensus weight node "
- "selection for rule %s",
- bandwidth_weight_rule_to_string(rule));
- return -1;
- }
- weight_scale = networkstatus_get_weight_scale_param(NULL);
- if (rule == WEIGHT_FOR_GUARD) {
- Wg = networkstatus_get_bw_weight(NULL, "Wgg", -1);
- Wm = networkstatus_get_bw_weight(NULL, "Wgm", -1); /* Bridges */
- We = 0;
- Wd = networkstatus_get_bw_weight(NULL, "Wgd", -1);
- Wgb = networkstatus_get_bw_weight(NULL, "Wgb", -1);
- Wmb = networkstatus_get_bw_weight(NULL, "Wmb", -1);
- Web = networkstatus_get_bw_weight(NULL, "Web", -1);
- Wdb = networkstatus_get_bw_weight(NULL, "Wdb", -1);
- } else if (rule == WEIGHT_FOR_MID) {
- Wg = networkstatus_get_bw_weight(NULL, "Wmg", -1);
- Wm = networkstatus_get_bw_weight(NULL, "Wmm", -1);
- We = networkstatus_get_bw_weight(NULL, "Wme", -1);
- Wd = networkstatus_get_bw_weight(NULL, "Wmd", -1);
- Wgb = networkstatus_get_bw_weight(NULL, "Wgb", -1);
- Wmb = networkstatus_get_bw_weight(NULL, "Wmb", -1);
- Web = networkstatus_get_bw_weight(NULL, "Web", -1);
- Wdb = networkstatus_get_bw_weight(NULL, "Wdb", -1);
- } else if (rule == WEIGHT_FOR_EXIT) {
- // Guards CAN be exits if they have weird exit policies
- // They are d then I guess...
- We = networkstatus_get_bw_weight(NULL, "Wee", -1);
- Wm = networkstatus_get_bw_weight(NULL, "Wem", -1); /* Odd exit policies */
- Wd = networkstatus_get_bw_weight(NULL, "Wed", -1);
- Wg = networkstatus_get_bw_weight(NULL, "Weg", -1); /* Odd exit policies */
- Wgb = networkstatus_get_bw_weight(NULL, "Wgb", -1);
- Wmb = networkstatus_get_bw_weight(NULL, "Wmb", -1);
- Web = networkstatus_get_bw_weight(NULL, "Web", -1);
- Wdb = networkstatus_get_bw_weight(NULL, "Wdb", -1);
- } else if (rule == WEIGHT_FOR_DIR) {
- We = networkstatus_get_bw_weight(NULL, "Wbe", -1);
- Wm = networkstatus_get_bw_weight(NULL, "Wbm", -1);
- Wd = networkstatus_get_bw_weight(NULL, "Wbd", -1);
- Wg = networkstatus_get_bw_weight(NULL, "Wbg", -1);
- Wgb = Wmb = Web = Wdb = weight_scale;
- } else if (rule == NO_WEIGHTING) {
- Wg = Wm = We = Wd = weight_scale;
- Wgb = Wmb = Web = Wdb = weight_scale;
- }
- if (Wg < 0 || Wm < 0 || We < 0 || Wd < 0 || Wgb < 0 || Wmb < 0 || Wdb < 0
- || Web < 0) {
- log_debug(LD_CIRC,
- "Got negative bandwidth weights. Defaulting to naive selection"
- " algorithm.");
- Wg = Wm = We = Wd = weight_scale;
- Wgb = Wmb = Web = Wdb = weight_scale;
- }
- Wg /= weight_scale;
- Wm /= weight_scale;
- We /= weight_scale;
- Wd /= weight_scale;
- Wgb /= weight_scale;
- Wmb /= weight_scale;
- Web /= weight_scale;
- Wdb /= weight_scale;
- bandwidths = tor_calloc(smartlist_len(sl), sizeof(double));
- // Cycle through smartlist and total the bandwidth.
- static int warned_missing_bw = 0;
- SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {
- int is_exit = 0, is_guard = 0, is_dir = 0, this_bw = 0;
- double weight = 1;
- double weight_without_guard_flag = 0; /* Used for guardfraction */
- double final_weight = 0;
- is_exit = node->is_exit && ! node->is_bad_exit;
- is_guard = node->is_possible_guard;
- is_dir = node_is_dir(node);
- if (node->rs) {
- if (!node->rs->has_bandwidth) {
- /* This should never happen, unless all the authorities downgrade
- * to 0.2.0 or rogue routerstatuses get inserted into our consensus. */
- if (! warned_missing_bw) {
- log_warn(LD_BUG,
- "Consensus is missing some bandwidths. Using a naive "
- "router selection algorithm");
- warned_missing_bw = 1;
- }
- this_bw = 30000; /* Chosen arbitrarily */
- } else {
- this_bw = kb_to_bytes(node->rs->bandwidth_kb);
- }
- } else if (node->ri) {
- /* bridge or other descriptor not in our consensus */
- this_bw = bridge_get_advertised_bandwidth_bounded(node->ri);
- } else {
- /* We can't use this one. */
- continue;
- }
- if (is_guard && is_exit) {
- weight = (is_dir ? Wdb*Wd : Wd);
- weight_without_guard_flag = (is_dir ? Web*We : We);
- } else if (is_guard) {
- weight = (is_dir ? Wgb*Wg : Wg);
- weight_without_guard_flag = (is_dir ? Wmb*Wm : Wm);
- } else if (is_exit) {
- weight = (is_dir ? Web*We : We);
- } else { // middle
- weight = (is_dir ? Wmb*Wm : Wm);
- }
- /* These should be impossible; but overflows here would be bad, so let's
- * make sure. */
- if (this_bw < 0)
- this_bw = 0;
- if (weight < 0.0)
- weight = 0.0;
- if (weight_without_guard_flag < 0.0)
- weight_without_guard_flag = 0.0;
- /* If guardfraction information is available in the consensus, we
- * want to calculate this router's bandwidth according to its
- * guardfraction. Quoting from proposal236:
- *
- * Let Wpf denote the weight from the 'bandwidth-weights' line a
- * client would apply to N for position p if it had the guard
- * flag, Wpn the weight if it did not have the guard flag, and B the
- * measured bandwidth of N in the consensus. Then instead of choosing
- * N for position p proportionally to Wpf*B or Wpn*B, clients should
- * choose N proportionally to F*Wpf*B + (1-F)*Wpn*B.
- */
- if (node->rs && node->rs->has_guardfraction && rule != WEIGHT_FOR_GUARD) {
- /* XXX The assert should actually check for is_guard. However,
- * that crashes dirauths because of #13297. This should be
- * equivalent: */
- tor_assert(node->rs->is_possible_guard);
- guard_get_guardfraction_bandwidth(&guardfraction_bw,
- this_bw,
- node->rs->guardfraction_percentage);
- /* Calculate final_weight = F*Wpf*B + (1-F)*Wpn*B */
- final_weight =
- guardfraction_bw.guard_bw * weight +
- guardfraction_bw.non_guard_bw * weight_without_guard_flag;
- log_debug(LD_GENERAL, "%s: Guardfraction weight %f instead of %f (%s)",
- node->rs->nickname, final_weight, weight*this_bw,
- bandwidth_weight_rule_to_string(rule));
- } else { /* no guardfraction information. calculate the weight normally. */
- final_weight = weight*this_bw;
- }
- bandwidths[node_sl_idx] = final_weight;
- total_bandwidth += final_weight;
- } SMARTLIST_FOREACH_END(node);
- log_debug(LD_CIRC, "Generated weighted bandwidths for rule %s based "
- "on weights "
- "Wg=%f Wm=%f We=%f Wd=%f with total bw %f",
- bandwidth_weight_rule_to_string(rule),
- Wg, Wm, We, Wd, total_bandwidth);
- *bandwidths_out = bandwidths;
- if (total_bandwidth_out) {
- *total_bandwidth_out = total_bandwidth;
- }
- return 0;
- }
- /** For all nodes in <b>sl</b>, return the fraction of those nodes, weighted
- * by their weighted bandwidths with rule <b>rule</b>, for which we have
- * descriptors.
- *
- * If <b>for_direct_connect</b> is true, we intend to connect to the node
- * directly, as the first hop of a circuit; otherwise, we intend to connect
- * to it indirectly, or use it as if we were connecting to it indirectly. */
- double
- frac_nodes_with_descriptors(const smartlist_t *sl,
- bandwidth_weight_rule_t rule,
- int for_direct_conn)
- {
- double *bandwidths = NULL;
- double total, present;
- if (smartlist_len(sl) == 0)
- return 0.0;
- if (compute_weighted_bandwidths(sl, rule, &bandwidths, &total) < 0 ||
- total <= 0.0) {
- int n_with_descs = 0;
- SMARTLIST_FOREACH(sl, const node_t *, node, {
- if (node_has_preferred_descriptor(node, for_direct_conn))
- n_with_descs++;
- });
- tor_free(bandwidths);
- return ((double)n_with_descs) / smartlist_len(sl);
- }
- present = 0.0;
- SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {
- if (node_has_preferred_descriptor(node, for_direct_conn))
- present += bandwidths[node_sl_idx];
- } SMARTLIST_FOREACH_END(node);
- tor_free(bandwidths);
- return present / total;
- }
- /** Choose a random element of status list <b>sl</b>, weighted by
- * the advertised bandwidth of each node */
- const node_t *
- node_sl_choose_by_bandwidth(const smartlist_t *sl,
- bandwidth_weight_rule_t rule)
- { /*XXXX MOVE */
- return smartlist_choose_node_by_bandwidth_weights(sl, rule);
- }
- /** Given a <b>router</b>, add every node_t in its family (including the
- * node itself!) to <b>sl</b>.
- *
- * Note the type mismatch: This function takes a routerinfo, but adds nodes
- * to the smartlist!
- */
- static void
- routerlist_add_node_and_family(smartlist_t *sl, const routerinfo_t *router)
- {
- /* XXXX MOVE ? */
- node_t fake_node;
- const node_t *node = node_get_by_id(router->cache_info.identity_digest);
- if (node == NULL) {
- memset(&fake_node, 0, sizeof(fake_node));
- fake_node.ri = (routerinfo_t *)router;
- memcpy(fake_node.identity, router->cache_info.identity_digest, DIGEST_LEN);
- node = &fake_node;
- }
- nodelist_add_node_and_family(sl, node);
- }
- /** Return a random running node from the nodelist. Never
- * pick a node that is in
- * <b>excludedsmartlist</b>, or which matches <b>excludedset</b>,
- * even if they are the only nodes available.
- * If <b>CRN_NEED_UPTIME</b> is set in flags and any router has more than
- * a minimum uptime, return one of those.
- * If <b>CRN_NEED_CAPACITY</b> is set in flags, weight your choice by the
- * advertised capacity of each router.
- * If <b>CRN_NEED_GUARD</b> is set in flags, consider only Guard routers.
- * If <b>CRN_WEIGHT_AS_EXIT</b> is set in flags, we weight bandwidths as if
- * picking an exit node, otherwise we weight bandwidths for picking a relay
- * node (that is, possibly discounting exit nodes).
- * If <b>CRN_NEED_DESC</b> is set in flags, we only consider nodes that
- * have a routerinfo or microdescriptor -- that is, enough info to be
- * used to build a circuit.
- * If <b>CRN_PREF_ADDR</b> is set in flags, we only consider nodes that
- * have an address that is preferred by the ClientPreferIPv6ORPort setting
- * (regardless of this flag, we exclude nodes that aren't allowed by the
- * firewall, including ClientUseIPv4 0 and fascist_firewall_use_ipv6() == 0).
- */
- const node_t *
- router_choose_random_node(smartlist_t *excludedsmartlist,
- routerset_t *excludedset,
- router_crn_flags_t flags)
- { /* XXXX MOVE */
- const int need_uptime = (flags & CRN_NEED_UPTIME) != 0;
- const int need_capacity = (flags & CRN_NEED_CAPACITY) != 0;
- const int need_guard = (flags & CRN_NEED_GUARD) != 0;
- const int weight_for_exit = (flags & CRN_WEIGHT_AS_EXIT) != 0;
- const int need_desc = (flags & CRN_NEED_DESC) != 0;
- const int pref_addr = (flags & CRN_PREF_ADDR) != 0;
- const int direct_conn = (flags & CRN_DIRECT_CONN) != 0;
- const int rendezvous_v3 = (flags & CRN_RENDEZVOUS_V3) != 0;
- smartlist_t *sl=smartlist_new(),
- *excludednodes=smartlist_new();
- const node_t *choice = NULL;
- const routerinfo_t *r;
- bandwidth_weight_rule_t rule;
- tor_assert(!(weight_for_exit && need_guard));
- rule = weight_for_exit ? WEIGHT_FOR_EXIT :
- (need_guard ? WEIGHT_FOR_GUARD : WEIGHT_FOR_MID);
- SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), node_t *, node) {
- if (node_allows_single_hop_exits(node)) {
- /* Exclude relays that allow single hop exit circuits. This is an
- * obsolete option since 0.2.9.2-alpha and done by default in
- * 0.3.1.0-alpha. */
- smartlist_add(excludednodes, node);
- } else if (rendezvous_v3 &&
- !node_supports_v3_rendezvous_point(node)) {
- /* Exclude relays that do not support to rendezvous for a hidden service
- * version 3. */
- smartlist_add(excludednodes, node);
- }
- } SMARTLIST_FOREACH_END(node);
- /* If the node_t is not found we won't be to exclude ourself but we
- * won't be able to pick ourself in router_choose_random_node() so
- * this is fine to at least try with our routerinfo_t object. */
- if ((r = router_get_my_routerinfo()))
- routerlist_add_node_and_family(excludednodes, r);
- router_add_running_nodes_to_smartlist(sl, need_uptime, need_capacity,
- need_guard, need_desc, pref_addr,
- direct_conn);
- log_debug(LD_CIRC,
- "We found %d running nodes.",
- smartlist_len(sl));
- smartlist_subtract(sl,excludednodes);
- log_debug(LD_CIRC,
- "We removed %d excludednodes, leaving %d nodes.",
- smartlist_len(excludednodes),
- smartlist_len(sl));
- if (excludedsmartlist) {
- smartlist_subtract(sl,excludedsmartlist);
- log_debug(LD_CIRC,
- "We removed %d excludedsmartlist, leaving %d nodes.",
- smartlist_len(excludedsmartlist),
- smartlist_len(sl));
- }
- if (excludedset) {
- routerset_subtract_nodes(sl,excludedset);
- log_debug(LD_CIRC,
- "We removed excludedset, leaving %d nodes.",
- smartlist_len(sl));
- }
- // Always weight by bandwidth
- choice = node_sl_choose_by_bandwidth(sl, rule);
- smartlist_free(sl);
- if (!choice && (need_uptime || need_capacity || need_guard || pref_addr)) {
- /* try once more -- recurse but with fewer restrictions. */
- log_info(LD_CIRC,
- "We couldn't find any live%s%s%s routers; falling back "
- "to list of all routers.",
- need_capacity?", fast":"",
- need_uptime?", stable":"",
- need_guard?", guard":"");
- flags &= ~ (CRN_NEED_UPTIME|CRN_NEED_CAPACITY|CRN_NEED_GUARD|
- CRN_PREF_ADDR);
- choice = router_choose_random_node(
- excludedsmartlist, excludedset, flags);
- }
- smartlist_free(excludednodes);
- if (!choice) {
- log_warn(LD_CIRC,
- "No available nodes when trying to choose node. Failing.");
- }
- return choice;
- }
- /** Try to find a running directory authority. Flags are as for
- * router_pick_directory_server.
- */
- const routerstatus_t *
- router_pick_trusteddirserver(dirinfo_type_t type, int flags)
- {
- return router_pick_dirserver_generic(
- router_get_trusted_dir_servers_mutable(),
- type, flags);
- }
- /** Try to find a running fallback directory. Flags are as for
- * router_pick_directory_server.
- */
- const routerstatus_t *
- router_pick_fallback_dirserver(dirinfo_type_t type, int flags)
- {
- return router_pick_dirserver_generic(
- router_get_fallback_dir_servers_mutable(),
- type, flags);
- }
- /** Pick a random element from a list of dir_server_t, weighting by their
- * <b>weight</b> field. */
- static const dir_server_t *
- dirserver_choose_by_weight(const smartlist_t *servers, double authority_weight)
- {
- int n = smartlist_len(servers);
- int i;
- double *weights_dbl;
- uint64_t *weights_u64;
- const dir_server_t *ds;
- weights_dbl = tor_calloc(n, sizeof(double));
- weights_u64 = tor_calloc(n, sizeof(uint64_t));
- for (i = 0; i < n; ++i) {
- ds = smartlist_get(servers, i);
- weights_dbl[i] = ds->weight;
- if (ds->is_authority)
- weights_dbl[i] *= authority_weight;
- }
- scale_array_elements_to_u64(weights_u64, weights_dbl, n, NULL);
- i = choose_array_element_by_weight(weights_u64, n);
- tor_free(weights_dbl);
- tor_free(weights_u64);
- return (i < 0) ? NULL : smartlist_get(servers, i);
- }
- /** Choose randomly from among the dir_server_ts in sourcelist that
- * are up. Flags are as for router_pick_directory_server_impl().
- */
- static const routerstatus_t *
- router_pick_trusteddirserver_impl(const smartlist_t *sourcelist,
- dirinfo_type_t type, int flags,
- int *n_busy_out)
- {
- const or_options_t *options = get_options();
- smartlist_t *direct, *tunnel;
- smartlist_t *overloaded_direct, *overloaded_tunnel;
- const routerinfo_t *me = router_get_my_routerinfo();
- const routerstatus_t *result = NULL;
- time_t now = time(NULL);
- const int requireother = ! (flags & PDS_ALLOW_SELF);
- const int fascistfirewall = ! (flags & PDS_IGNORE_FASCISTFIREWALL);
- const int no_serverdesc_fetching =(flags & PDS_NO_EXISTING_SERVERDESC_FETCH);
- const int no_microdesc_fetching =(flags & PDS_NO_EXISTING_MICRODESC_FETCH);
- const double auth_weight =
- (sourcelist == router_get_fallback_dir_servers()) ?
- options->DirAuthorityFallbackRate : 1.0;
- smartlist_t *pick_from;
- int n_busy = 0;
- int try_excluding = 1, n_excluded = 0;
- int try_ip_pref = 1;
- if (!sourcelist)
- return NULL;
- retry_search:
- direct = smartlist_new();
- tunnel = smartlist_new();
- overloaded_direct = smartlist_new();
- overloaded_tunnel = smartlist_new();
- const int skip_or_fw = router_skip_or_reachability(options, try_ip_pref);
- const int skip_dir_fw = router_skip_dir_reachability(options, try_ip_pref);
- const int must_have_or = directory_must_use_begindir(options);
- SMARTLIST_FOREACH_BEGIN(sourcelist, const dir_server_t *, d)
- {
- int is_overloaded =
- d->fake_status.last_dir_503_at + DIR_503_TIMEOUT > now;
- if (!d->is_running) continue;
- if ((type & d->type) == 0)
- continue;
- SKIP_MISSING_TRUSTED_EXTRAINFO(type, d->digest);
- if (requireother && me && router_digest_is_me(d->digest))
- continue;
- if (try_excluding &&
- routerset_contains_routerstatus(options->ExcludeNodes,
- &d->fake_status, -1)) {
- ++n_excluded;
- continue;
- }
- if (router_is_already_dir_fetching_(d->addr,
- &d->ipv6_addr,
- d->dir_port,
- no_serverdesc_fetching,
- no_microdesc_fetching)) {
- ++n_busy;
- continue;
- }
- /* Clients use IPv6 addresses if the server has one and the client
- * prefers IPv6.
- * Add the router if its preferred address and port are reachable.
- * If we don't get any routers, we'll try again with the non-preferred
- * address for each router (if any). (To ensure correct load-balancing
- * we try routers that only have one address both times.)
- */
- if (!fascistfirewall || skip_or_fw ||
- fascist_firewall_allows_dir_server(d, FIREWALL_OR_CONNECTION,
- try_ip_pref))
- smartlist_add(is_overloaded ? overloaded_tunnel : tunnel, (void*)d);
- else if (!must_have_or && (skip_dir_fw ||
- fascist_firewall_allows_dir_server(d, FIREWALL_DIR_CONNECTION,
- try_ip_pref)))
- smartlist_add(is_overloaded ? overloaded_direct : direct, (void*)d);
- }
- SMARTLIST_FOREACH_END(d);
- if (smartlist_len(tunnel)) {
- pick_from = tunnel;
- } else if (smartlist_len(overloaded_tunnel)) {
- pick_from = overloaded_tunnel;
- } else if (smartlist_len(direct)) {
- pick_from = direct;
- } else {
- pick_from = overloaded_direct;
- }
- {
- const dir_server_t *selection =
- dirserver_choose_by_weight(pick_from, auth_weight);
- if (selection)
- result = &selection->fake_status;
- }
- smartlist_free(direct);
- smartlist_free(tunnel);
- smartlist_free(overloaded_direct);
- smartlist_free(overloaded_tunnel);
- RETRY_ALTERNATE_IP_VERSION(retry_search);
- RETRY_WITHOUT_EXCLUDE(retry_search);
- router_picked_poor_directory_log(result);
- if (n_busy_out)
- *n_busy_out = n_busy;
- return result;
- }
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