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tor/src/feature/nodelist/node_select.c
Nick Mathewson 2f683465d4 Bump copyright date to 2019
2019-01-16 12:33:22 -05:00

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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) 2007-2019, 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/dirclient/dirclient.h"
#include "feature/dircommon/directory.h"
#include "feature/nodelist/describe.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 "feature/relay/routermode.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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