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Merge commit 'sebastian/bug2317' into maint-0.2.2

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This commit is contained in:
Roger Dingledine 2011-01-15 21:54:49 -05:00
commit 7699014e1e
16 changed files with 193 additions and 60 deletions
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9
changes/bug2317 Normal file
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@ -0,0 +1,9 @@
o Major features:
- Introduce minimum/maximum values that a client is going to believe
in a consensus. This helps to avoid crashes or worse when a param
has a weird value.
o Major bugfixes:
- Prevent crash/heap corruption when cbtnumnodes consensus parameter is
set to 0 or large values. Fixes bug 2317.

8
doc/spec/dir-spec.txt
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@ -1161,12 +1161,14 @@
research indicates that a lower value would mean fewer cells in
transit in the network at any given time. Obeyed by Tor 0.2.1.20
and later.
Min: 100, Max: 1000
"CircuitPriorityHalflifeMsec" -- the halflife parameter used when
weighting which circuit will send the next cell. Obeyed by Tor
0.2.2.10-alpha and later. (Versions of Tor between 0.2.2.7-alpha
and 0.2.2.10-alpha recognized a "CircPriorityHalflifeMsec" parameter,
but mishandled it badly.)
Min: -1, Max: 2147483647 (INT32_MAX)
"perconnbwrate" and "perconnbwburst" -- if set, each relay sets
up a separate token bucket for every client OR connection,
@ -1176,12 +1178,14 @@
and later. (Note that relays running 0.2.2.7-alpha through
0.2.2.14-alpha looked for bwconnrate and bwconnburst, but then
did the wrong thing with them; see bug 1830 for details.)
Min: 1, Max: 2147483647 (INT32_MAX)
"refuseunknownexits" -- if set and non-zero, exit relays look at
"refuseunknownexits" -- if set to one, exit relays look at
the previous hop of circuits that ask to open an exit stream,
and refuse to exit if they don't recognize it as a relay. The
goal is to make it harder for people to use them as one-hop
proxies. See trac entry 1751 for details.
Min: 0, Max: 1
See also "2.4.5. Consensus parameters governing behavior"
in path-spec.txt for a series of circuit build time related
@ -1820,7 +1824,7 @@
To ensure consensus, all calculations are performed using integer math
with a fixed precision determined by the bwweightscale consensus
parameter (defaults at 10000).
parameter (defaults at 10000, Min: 1, Max: INT32_MAX).
For future balancing improvements, Tor clients support 11 additional weights
for directory requests and middle weighting. These weights are currently

28
doc/spec/path-spec.txt
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@ -421,57 +421,79 @@ of their choices.
cbtdisabled
Default: 0
Effect: If non-zero, all CircuitBuildTime learning code should be
Min: 0
Max: 1
Effect: If 1, all CircuitBuildTime learning code should be
disabled and history should be discarded. For use in
emergency situations only.
cbtnummodes
Default: 3
Min: 1
Max: 20
Effect: This value governs how many modes to use in the weighted
average calculation of Pareto paramter Xm. A value of 3 introduces
average calculation of Pareto parameter Xm. A value of 3 introduces
some bias (2-5% of CDF) under ideal conditions, but allows for better
performance in the event that a client chooses guard nodes of radically
different performance characteristics.
cbtrecentcount
Default: 20
Min: 3
Max: 1000
Effect: This is the number of circuit build times to keep track of
for the following option.
cbtmaxtimeouts
Default: 18
Min: 3
Max: 10000
Effect: When this many timeouts happen in the last 'cbtrecentcount'
circuit attempts, the client should discard all of its
history and begin learning a fresh timeout value.
cbtmincircs
Default: 100
Min: 1
Max: 10000
Effect: This is the minimum number of circuits to build before
computing a timeout.
cbtquantile
Default: 80
Min: 10
Max: 99
Effect: This is the position on the quantile curve to use to set the
timeout value. It is a percent (0-99).
timeout value. It is a percent (10-99).
cbtclosequantile
Default: 95
Min: Value of cbtquantile parameter
Max: 99
Effect: This is the position on the quantile curve to use to set the
timeout value to use to actually close circuits. It is a percent
(0-99).
cbttestfreq
Default: 60
Min: 1
Max: 2147483647 (INT32_MAX)
Effect: Describes how often in seconds to build a test circuit to
gather timeout values. Only applies if less than 'cbtmincircs'
have been recorded.
cbtmintimeout
Default: 2000
Min: 500
Max: 2147483647 (INT32_MAX)
Effect: This is the minimum allowed timeout value in milliseconds.
The minimum is to prevent rounding to 0 (we only check once
per second).
cbtinitialtimeout
Default: 60000
Min: Value of cbtmintimeout
Max: 2147483647 (INT32_MAX)
Effect: This is the timeout value to use before computing a timeout,
in milliseconds.

84
src/or/circuitbuild.c
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@ -106,7 +106,7 @@ circuit_build_times_disabled(void)
return 0;
} else {
int consensus_disabled = networkstatus_get_param(NULL, "cbtdisabled",
0);
0, 0, 1);
int config_disabled = !get_options()->LearnCircuitBuildTimeout;
int dirauth_disabled = get_options()->AuthoritativeDir;
int state_disabled = (get_or_state()->LastWritten == -1);
@ -128,16 +128,19 @@ circuit_build_times_disabled(void)
static int32_t
circuit_build_times_max_timeouts(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtmaxtimeouts",
CBT_DEFAULT_MAX_RECENT_TIMEOUT_COUNT);
return num;
return networkstatus_get_param(NULL, "cbtmaxtimeouts",
CBT_DEFAULT_MAX_RECENT_TIMEOUT_COUNT,
CBT_MIN_MAX_RECENT_TIMEOUT_COUNT,
CBT_MAX_MAX_RECENT_TIMEOUT_COUNT);
}
static int32_t
circuit_build_times_default_num_xm_modes(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtnummodes",
CBT_DEFAULT_NUM_XM_MODES);
CBT_DEFAULT_NUM_XM_MODES,
CBT_MIN_NUM_XM_MODES,
CBT_MAX_NUM_XM_MODES);
return num;
}
@ -145,7 +148,9 @@ static int32_t
circuit_build_times_min_circs_to_observe(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtmincircs",
CBT_DEFAULT_MIN_CIRCUITS_TO_OBSERVE);
CBT_DEFAULT_MIN_CIRCUITS_TO_OBSERVE,
CBT_MIN_MIN_CIRCUITS_TO_OBSERVE,
CBT_MAX_MIN_CIRCUITS_TO_OBSERVE);
return num;
}
@ -161,24 +166,46 @@ double
circuit_build_times_quantile_cutoff(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtquantile",
CBT_DEFAULT_QUANTILE_CUTOFF);
CBT_DEFAULT_QUANTILE_CUTOFF,
CBT_MIN_QUANTILE_CUTOFF,
CBT_MAX_QUANTILE_CUTOFF);
return num/100.0;
}
int
circuit_build_times_get_bw_scale(networkstatus_t *ns)
{
return networkstatus_get_param(ns, "bwweightscale",
BW_WEIGHT_SCALE,
BW_MIN_WEIGHT_SCALE,
BW_MAX_WEIGHT_SCALE);
}
static double
circuit_build_times_close_quantile(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtclosequantile",
CBT_DEFAULT_CLOSE_QUANTILE);
return num/100.0;
int32_t param;
/* Cast is safe - circuit_build_times_quantile_cutoff() is capped */
int32_t min = (int)tor_lround(100*circuit_build_times_quantile_cutoff());
param = networkstatus_get_param(NULL, "cbtclosequantile",
CBT_DEFAULT_CLOSE_QUANTILE,
CBT_MIN_CLOSE_QUANTILE,
CBT_MAX_CLOSE_QUANTILE);
if (param < min) {
log_warn(LD_DIR, "Consensus parameter cbtclosequantile is "
"too small, raising to %d", min);
param = min;
}
return param / 100.0;
}
static int32_t
circuit_build_times_test_frequency(void)
{
int32_t num = networkstatus_get_param(NULL, "cbttestfreq",
CBT_DEFAULT_TEST_FREQUENCY);
CBT_DEFAULT_TEST_FREQUENCY,
CBT_MIN_TEST_FREQUENCY,
CBT_MAX_TEST_FREQUENCY);
return num;
}
@ -186,24 +213,35 @@ static int32_t
circuit_build_times_min_timeout(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtmintimeout",
CBT_DEFAULT_TIMEOUT_MIN_VALUE);
CBT_DEFAULT_TIMEOUT_MIN_VALUE,
CBT_MIN_TIMEOUT_MIN_VALUE,
CBT_MAX_TIMEOUT_MIN_VALUE);
return num;
}
int32_t
circuit_build_times_initial_timeout(void)
{
int32_t num = networkstatus_get_param(NULL, "cbtinitialtimeout",
CBT_DEFAULT_TIMEOUT_INITIAL_VALUE);
return num;
int32_t min = circuit_build_times_min_timeout();
int32_t param = networkstatus_get_param(NULL, "cbtinitialtimeout",
CBT_DEFAULT_TIMEOUT_INITIAL_VALUE,
CBT_MIN_TIMEOUT_INITIAL_VALUE,
CBT_MAX_TIMEOUT_INITIAL_VALUE);
if (param < min) {
log_warn(LD_DIR, "Consensus parameter cbtinitialtimeout is too small, "
"raising to %d", min);
param = min;
}
return param;
}
static int32_t
circuit_build_times_recent_circuit_count(void)
circuit_build_times_recent_circuit_count(networkstatus_t *ns)
{
int32_t num = networkstatus_get_param(NULL, "cbtrecentcount",
CBT_DEFAULT_RECENT_CIRCUITS);
return num;
return networkstatus_get_param(ns, "cbtrecentcount",
CBT_DEFAULT_RECENT_CIRCUITS,
CBT_MIN_RECENT_CIRCUITS,
CBT_MAX_RECENT_CIRCUITS);
}
/**
@ -216,8 +254,7 @@ void
circuit_build_times_new_consensus_params(circuit_build_times_t *cbt,
networkstatus_t *ns)
{
int32_t num = networkstatus_get_param(ns, "cbtrecentcount",
CBT_DEFAULT_RECENT_CIRCUITS);
int32_t num = circuit_build_times_recent_circuit_count(ns);
if (num > 0 && num != cbt->liveness.num_recent_circs) {
int8_t *recent_circs;
@ -307,7 +344,8 @@ void
circuit_build_times_init(circuit_build_times_t *cbt)
{
memset(cbt, 0, sizeof(*cbt));
cbt->liveness.num_recent_circs = circuit_build_times_recent_circuit_count();
cbt->liveness.num_recent_circs =
circuit_build_times_recent_circuit_count(NULL);
cbt->liveness.timeouts_after_firsthop = tor_malloc_zero(sizeof(int8_t)*
cbt->liveness.num_recent_circs);
cbt->close_ms = cbt->timeout_ms = circuit_build_times_get_initial_timeout();

2
src/or/circuitbuild.h
View File

@ -121,5 +121,7 @@ void circuit_build_times_network_is_live(circuit_build_times_t *cbt);
int circuit_build_times_network_check_live(circuit_build_times_t *cbt);
void circuit_build_times_network_circ_success(circuit_build_times_t *cbt);
int circuit_build_times_get_bw_scale(networkstatus_t *ns);
#endif

4
src/or/circuitlist.c
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@ -384,7 +384,9 @@ circuit_purpose_to_controller_string(uint8_t purpose)
int32_t
circuit_initial_package_window(void)
{
int32_t num = networkstatus_get_param(NULL, "circwindow", CIRCWINDOW_START);
int32_t num = networkstatus_get_param(NULL, "circwindow", CIRCWINDOW_START,
CIRCWINDOW_START_MIN,
CIRCWINDOW_START_MAX);
/* If the consensus tells us a negative number, we'd assert. */
if (num < 0)
num = CIRCWINDOW_START;

8
src/or/connection_or.c
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@ -370,11 +370,11 @@ connection_or_update_token_buckets_helper(or_connection_t *conn, int reset,
* bandwidth parameters in the consensus, but allow local config
* options to override. */
rate = options->PerConnBWRate ? (int)options->PerConnBWRate :
(int)networkstatus_get_param(NULL, "perconnbwrate",
(int)options->BandwidthRate);
networkstatus_get_param(NULL, "perconnbwrate",
(int)options->BandwidthRate, 1, INT32_MAX);
burst = options->PerConnBWBurst ? (int)options->PerConnBWBurst :
(int)networkstatus_get_param(NULL, "perconnbwburst",
(int)options->BandwidthBurst);
networkstatus_get_param(NULL, "perconnbwburst",
(int)options->BandwidthBurst, 1, INT32_MAX);
}
conn->bandwidthrate = rate;

3
src/or/dirvote.h
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@ -19,9 +19,6 @@
/** Smallest allowable voting interval. */
#define MIN_VOTE_INTERVAL 300
/** Precision multiplier for the Bw weights */
#define BW_WEIGHT_SCALE 10000
void dirvote_free_all(void);
/* vote manipulation */

52
src/or/networkstatus.c
View File

@ -2125,32 +2125,52 @@ networkstatus_dump_bridge_status_to_file(time_t now)
tor_free(status);
}
int32_t
static int32_t
get_net_param_from_list(smartlist_t *net_params, const char *param_name,
int default_val)
int32_t default_val, int32_t min_val, int32_t max_val)
{
int32_t res = default_val;
size_t name_len = strlen(param_name);
tor_assert(max_val > min_val);
tor_assert(min_val <= default_val);
tor_assert(max_val >= default_val);
SMARTLIST_FOREACH_BEGIN(net_params, const char *, p) {
if (!strcmpstart(p, param_name) && p[name_len] == '=') {
int ok=0;
long v = tor_parse_long(p+name_len+1, 10, INT32_MIN,
INT32_MAX, &ok, NULL);
if (ok)
return (int32_t) v;
if (ok) {
res = (int32_t) v;
break;
}
}
} SMARTLIST_FOREACH_END(p);
return default_val;
if (res < min_val) {
log_warn(LD_DIR, "Consensus parameter %s is too small. Got %d, raising to "
"%d.", param_name, res, min_val);
res = min_val;
} else if (res > max_val) {
log_warn(LD_DIR, "Consensus parameter %s is too large. Got %d, capping to "
"%d.", param_name, res, max_val);
res = max_val;
}
return res;
}
/** Return the value of a integer parameter from the networkstatus <b>ns</b>
* whose name is <b>param_name</b>. If <b>ns</b> is NULL, try loading the
* latest consensus ourselves. Return <b>default_val</b> if no latest
* consensus, or if it has no parameter called <b>param_name</b>. */
* consensus, or if it has no parameter called <b>param_name</b>.
* Make sure the value parsed from the consensus is at least
* <b>min_val</b> and at most <b>max_val</b> and raise/cap the parsed value
* if necessary. */
int32_t
networkstatus_get_param(networkstatus_t *ns, const char *param_name,
int32_t default_val)
int32_t default_val, int32_t min_val, int32_t max_val)
{
if (!ns) /* if they pass in null, go find it ourselves */
ns = networkstatus_get_latest_consensus();
@ -2158,24 +2178,36 @@ networkstatus_get_param(networkstatus_t *ns, const char *param_name,
if (!ns || !ns->net_params)
return default_val;
return get_net_param_from_list(ns->net_params, param_name, default_val);
return get_net_param_from_list(ns->net_params, param_name,
default_val, min_val, max_val);
}
/** Return the value of a integer bw weight parameter from the networkstatus
* <b>ns</b> whose name is <b>weight_name</b>. If <b>ns</b> is NULL, try
* loading the latest consensus ourselves. Return <b>default_val</b> if no
* latest consensus, or if it has no parameter called <b>param_name</b>. */
* latest consensus, or if it has no parameter called <b>weight_name</b>. */
int32_t
networkstatus_get_bw_weight(networkstatus_t *ns, const char *weight_name,
int32_t default_val)
{
int32_t param;
int max;
if (!ns) /* if they pass in null, go find it ourselves */
ns = networkstatus_get_latest_consensus();
if (!ns || !ns->weight_params)
return default_val;
return get_net_param_from_list(ns->weight_params, weight_name, default_val);
max = circuit_build_times_get_bw_scale(ns);
param = get_net_param_from_list(ns->weight_params, weight_name,
default_val, -1,
BW_MAX_WEIGHT_SCALE);
if (param > max) {
log_warn(LD_DIR, "Value of consensus weight %s was too large, capping "
"to %d", weight_name, max);
param = max;
}
return param;
}
/** Return the name of the consensus flavor <b>flav</b> as used to identify

5
src/or/networkstatus.h
View File

@ -81,10 +81,9 @@ void signed_descs_update_status_from_consensus_networkstatus(
char *networkstatus_getinfo_helper_single(routerstatus_t *rs);
char *networkstatus_getinfo_by_purpose(const char *purpose_string, time_t now);
void networkstatus_dump_bridge_status_to_file(time_t now);
int32_t get_net_param_from_list(smartlist_t *net_params, const char *name,
int default_val);
int32_t networkstatus_get_param(networkstatus_t *ns, const char *param_name,
int32_t default_val);
int32_t default_val, int32_t min_val,
int32_t max_val);
int getinfo_helper_networkstatus(control_connection_t *conn,
const char *question, char **answer,
const char **errmsg);

27
src/or/or.h
View File

@ -765,6 +765,8 @@ typedef enum {
/** Initial value for both sides of a circuit transmission window when the
* circuit is initialized. Measured in cells. */
#define CIRCWINDOW_START 1000
#define CIRCWINDOW_START_MIN 100
#define CIRCWINDOW_START_MAX 1000
/** Amount to increment a circuit window when we get a circuit SENDME. */
#define CIRCWINDOW_INCREMENT 100
/** Initial value on both sides of a stream transmission window when the
@ -2942,6 +2944,11 @@ struct socks_request_t {
/* Circuit Build Timeout "public" structures. */
/** Precision multiplier for the Bw weights */
#define BW_WEIGHT_SCALE 10000
#define BW_MIN_WEIGHT_SCALE 1
#define BW_MAX_WEIGHT_SCALE INT32_MAX
/** Total size of the circuit timeout history to accumulate.
* 1000 is approx 2.5 days worth of continual-use circuits. */
#define CBT_NCIRCUITS_TO_OBSERVE 1000
@ -2951,6 +2958,8 @@ struct socks_request_t {
/** Number of modes to use in the weighted-avg computation of Xm */
#define CBT_DEFAULT_NUM_XM_MODES 3
#define CBT_MIN_NUM_XM_MODES 1
#define CBT_MAX_NUM_XM_MODES 20
/** A build_time_t is milliseconds */
typedef uint32_t build_time_t;
@ -2972,12 +2981,16 @@ typedef uint32_t build_time_t;
* build in terms of CDF quantile.
*/
#define CBT_DEFAULT_CLOSE_QUANTILE 95
#define CBT_MIN_CLOSE_QUANTILE CBT_MIN_QUANTILE_CUTOFF
#define CBT_MAX_CLOSE_QUANTILE CBT_MAX_QUANTILE_CUTOFF
/**
* How many circuits count as recent when considering if the
* connection has gone gimpy or changed.
*/
#define CBT_DEFAULT_RECENT_CIRCUITS 20
#define CBT_MIN_RECENT_CIRCUITS 3
#define CBT_MAX_RECENT_CIRCUITS 1000
/**
* Maximum count of timeouts that finish the first hop in the past
@ -2988,25 +3001,37 @@ typedef uint32_t build_time_t;
* gives us.
*/
#define CBT_DEFAULT_MAX_RECENT_TIMEOUT_COUNT (CBT_DEFAULT_RECENT_CIRCUITS*9/10)
#define CBT_MIN_MAX_RECENT_TIMEOUT_COUNT 3
#define CBT_MAX_MAX_RECENT_TIMEOUT_COUNT 10000
/** Minimum circuits before estimating a timeout */
#define CBT_DEFAULT_MIN_CIRCUITS_TO_OBSERVE 100
#define CBT_MIN_MIN_CIRCUITS_TO_OBSERVE 1
#define CBT_MAX_MIN_CIRCUITS_TO_OBSERVE 10000
/** Cutoff percentile on the CDF for our timeout estimation. */
#define CBT_DEFAULT_QUANTILE_CUTOFF 80
#define CBT_MIN_QUANTILE_CUTOFF 10
#define CBT_MAX_QUANTILE_CUTOFF 99
double circuit_build_times_quantile_cutoff(void);
/** How often in seconds should we build a test circuit */
#define CBT_DEFAULT_TEST_FREQUENCY 60
#define CBT_MIN_TEST_FREQUENCY 1
#define CBT_MAX_TEST_FREQUENCY INT32_MAX
/** Lowest allowable value for CircuitBuildTimeout in milliseconds */
#define CBT_DEFAULT_TIMEOUT_MIN_VALUE (1500)
#define CBT_MIN_TIMEOUT_MIN_VALUE 500
#define CBT_MAX_TIMEOUT_MIN_VALUE INT32_MAX
/** Initial circuit build timeout in milliseconds */
#define CBT_DEFAULT_TIMEOUT_INITIAL_VALUE (60*1000)
#define CBT_MIN_TIMEOUT_INITIAL_VALUE CBT_MIN_TIMEOUT_MIN_VALUE
#define CBT_MAX_TIMEOUT_INITIAL_VALUE INT32_MAX
int32_t circuit_build_times_initial_timeout(void);
#if CBT_DEFAULT_MAX_RECENT_TIMEOUT_COUNT < 1
#if CBT_DEFAULT_MAX_RECENT_TIMEOUT_COUNT < CBT_MIN_MAX_RECENT_TIMEOUT_COUNT
#error "RECENT_CIRCUITS is set too low."
#endif

6
src/or/relay.c
View File

@ -1999,9 +1999,9 @@ cell_ewma_set_scale_factor(or_options_t *options, networkstatus_t *consensus)
if (options && options->CircuitPriorityHalflife >= -EPSILON) {
halflife = options->CircuitPriorityHalflife;
source = "CircuitPriorityHalflife in configuration";
} else if (consensus &&
(halflife_ms = networkstatus_get_param(
consensus, "CircuitPriorityHalflifeMsec", -1)) >= 0) {
} else if (consensus && (halflife_ms = networkstatus_get_param(
consensus, "CircuitPriorityHalflifeMsec",
-1, -1, INT32_MAX)) >= 0) {
halflife = ((double)halflife_ms)/1000.0;
source = "CircuitPriorityHalflifeMsec in consensus";
} else {

2
src/or/router.c
View File

@ -1068,7 +1068,7 @@ should_refuse_unknown_exits(or_options_t *options)
if (options->RefuseUnknownExits_ != -1) {
return options->RefuseUnknownExits_;
} else {
return networkstatus_get_param(NULL, "refuseunknownexits", 1);
return networkstatus_get_param(NULL, "refuseunknownexits", 1, 0, 1);
}
}

3
src/or/routerlist.c
View File

@ -1650,8 +1650,7 @@ smartlist_choose_by_bandwidth_weights(smartlist_t *sl,
return NULL;
}
weight_scale = networkstatus_get_param(NULL, "bwweightscale",
BW_WEIGHT_SCALE);
weight_scale = circuit_build_times_get_bw_scale(NULL);
if (rule == WEIGHT_FOR_GUARD) {
Wg = networkstatus_get_bw_weight(NULL, "Wgg", -1);

3
src/or/routerparse.c
View File

@ -11,6 +11,7 @@
#include "or.h"
#include "config.h"
#include "circuitbuild.h"
#include "dirserv.h"
#include "dirvote.h"
#include "policies.h"
@ -2373,7 +2374,7 @@ networkstatus_verify_bw_weights(networkstatus_t *ns)
const char *casename = NULL;
int valid = 1;
weight_scale = networkstatus_get_param(ns, "bwweightscale", BW_WEIGHT_SCALE);
weight_scale = circuit_build_times_get_bw_scale(ns);
Wgg = networkstatus_get_bw_weight(ns, "Wgg", -1);
Wgm = networkstatus_get_bw_weight(ns, "Wgm", -1);
Wgd = networkstatus_get_bw_weight(ns, "Wgd", -1);

7
src/test/test_dir.c
View File

@ -609,8 +609,11 @@ test_dir_param_voting(void)
"abcd=20 c=60 cw=500 x-yz=-9 zzzzz=101", NULL, 0, 0);
smartlist_split_string(vote4.net_params,
"ab=900 abcd=200 c=1 cw=51 x-yz=100", NULL, 0, 0);
test_eq(100, networkstatus_get_param(&vote4, "x-yz", 50));
test_eq(222, networkstatus_get_param(&vote4, "foobar", 222));
test_eq(100, networkstatus_get_param(&vote4, "x-yz", 50, 0, 300));
test_eq(222, networkstatus_get_param(&vote4, "foobar", 222, 0, 300));
test_eq(80, networkstatus_get_param(&vote4, "ab", 12, 0, 80));
test_eq(-8, networkstatus_get_param(&vote4, "ab", -12, -100, -8));
test_eq(0, networkstatus_get_param(&vote4, "foobar", 0, -100, 8));
smartlist_add(votes, &vote1);
smartlist_add(votes, &vote2);