[tor-commits] [tor/master] Parse GuardFraction info from consensuses and votes.
nickm at torproject.org
nickm at torproject.org
Wed Feb 18 14:20:13 UTC 2015
commit f4a63f8eabbdd842ebeb97aabba92ea47c37a607
Author: George Kadianakis <desnacked at riseup.net>
Date: Thu Jan 29 14:57:00 2015 +0000
Parse GuardFraction info from consensuses and votes.
Also introduce the UseGuardFraction torrc option which decides whether
clients should use guardfraction information found in the consensus.
---
doc/tor.1.txt | 6 +++++
src/or/config.c | 1 +
src/or/entrynodes.c | 21 ++++++++++++++++
src/or/entrynodes.h | 2 ++
src/or/or.h | 6 +++++
src/or/routerparse.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++
src/or/routerparse.h | 7 ++++++
7 files changed, 108 insertions(+)
diff --git a/doc/tor.1.txt b/doc/tor.1.txt
index 3de3048..8ecece0 100644
--- a/doc/tor.1.txt
+++ b/doc/tor.1.txt
@@ -1122,6 +1122,12 @@ The following options are useful only for clients (that is, if
guardfraction file which contains information about how long relays
have been guards. (Default: unset)
+[[UseGuardFraction]] **UseGuardFraction** **0**|**1**|**auto**::
+ This torrc option specifies whether clients should use the
+ guardfraction information found in the consensus during path
+ selection. If it's set to 'auto', clients will do what the
+ UseGuardFraction consensus parameter tells them to do.
+
[[NumEntryGuards]] **NumEntryGuards** __NUM__::
If UseEntryGuards is set to 1, we will try to pick a total of NUM routers
as long-term entries for our circuits. If NUM is 0, we try to learn
diff --git a/src/or/config.c b/src/or/config.c
index 6349445..230ea7f 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -411,6 +411,7 @@ static config_var_t option_vars_[] = {
V(UseBridges, BOOL, "0"),
V(UseEntryGuards, BOOL, "1"),
V(UseEntryGuardsAsDirGuards, BOOL, "1"),
+ V(UseGuardFraction, AUTOBOOL, "auto"),
V(UseMicrodescriptors, AUTOBOOL, "auto"),
V(UseNTorHandshake, AUTOBOOL, "1"),
V(User, STRING, NULL),
diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c
index 5b0e342..a766f6c 100644
--- a/src/or/entrynodes.c
+++ b/src/or/entrynodes.c
@@ -1694,6 +1694,27 @@ getinfo_helper_entry_guards(control_connection_t *conn,
return 0;
}
+/** Return 0 if we should apply guardfraction information found in the
+ * consensus. A specific consensus can be specified with the
+ * <b>ns</b> argument, if NULL the most recent one will be picked.*/
+int
+should_apply_guardfraction(const networkstatus_t *ns)
+{
+ /* We need to check the corresponding torrc option and the consensus
+ * parameter if we need to. */
+ const or_options_t *options = get_options();
+
+ /* If UseGuardFraction is 'auto' then check the same-named consensus
+ * parameter. If the consensus parameter is not present, default to
+ * "off". */
+ if (options->UseGuardFraction == -1) {
+ return networkstatus_get_param(ns, "UseGuardFraction",
+ 0, /* default to "off" */
+ 0, 1);
+ }
+
+ return options->UseGuardFraction;
+}
/** A list of configured bridges. Whenever we actually get a descriptor
* for one, we add it as an entry guard. Note that the order of bridges
* in this list does not necessarily correspond to the order of bridges
diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h
index 7f3a4fb..96d832e 100644
--- a/src/or/entrynodes.h
+++ b/src/or/entrynodes.h
@@ -160,5 +160,7 @@ int validate_pluggable_transports_config(void);
double pathbias_get_close_success_count(entry_guard_t *guard);
double pathbias_get_use_success_count(entry_guard_t *guard);
+int should_apply_guardfraction(const networkstatus_t *ns);
+
#endif
diff --git a/src/or/or.h b/src/or/or.h
index 1f2231e..b8d4e1a 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3818,6 +3818,12 @@ typedef struct {
int NumEntryGuards; /**< How many entry guards do we try to establish? */
int UseEntryGuardsAsDirGuards; /** Boolean: Do we try to get directory info
* from a smallish number of fixed nodes? */
+
+ /** If 1, we use any guardfraction information we see in the
+ * consensus. If 0, we don't. If -1, let the consensus parameter
+ * decide. */
+ int UseGuardFraction;
+
int NumDirectoryGuards; /**< How many dir guards do we try to establish?
* If 0, use value from NumEntryGuards. */
int RephistTrackTime; /**< How many seconds do we keep rephist info? */
diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index a2bc8fb..8a00544 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -9,6 +9,8 @@
* \brief Code to parse and validate router descriptors and directories.
**/
+#define ROUTERPARSE_PRIVATE
+
#include "or.h"
#include "config.h"
#include "circuitstats.h"
@@ -23,6 +25,7 @@
#include "networkstatus.h"
#include "rephist.h"
#include "routerparse.h"
+#include "entrynodes.h"
#undef log
#include <math.h>
@@ -1792,6 +1795,63 @@ find_start_of_next_routerstatus(const char *s)
return eos;
}
+/** Parse the GuardFraction string from a consensus or vote.
+ *
+ * If <b>vote</b> or <b>vote_rs</b> are set the document getting
+ * parsed is a vote routerstatus. Otherwise it's a consensus. This is
+ * the same semantic as in routerstatus_parse_entry_from_string(). */
+STATIC int
+routerstatus_parse_guardfraction(const char *guardfraction_str,
+ networkstatus_t *vote,
+ vote_routerstatus_t *vote_rs,
+ routerstatus_t *rs)
+{
+ int ok;
+ const char *end_of_header = NULL;
+ int is_consensus = !vote_rs;
+ uint32_t guardfraction;
+
+ tor_assert(bool_eq(vote, vote_rs));
+
+ /* If this info comes from a consensus, but we should't apply
+ guardfraction, just exit. */
+ if (is_consensus && !should_apply_guardfraction(NULL)) {
+ return 0;
+ }
+
+ end_of_header = strchr(guardfraction_str, '=');
+ if (!end_of_header) {
+ return -1;
+ }
+
+ guardfraction = (uint32_t)tor_parse_ulong(end_of_header+1,
+ 10, 0, 100, &ok, NULL);
+ if (!ok) {
+ log_warn(LD_DIR, "Invalid GuardFraction %s", escaped(guardfraction_str));
+ return -1;
+ }
+
+ log_warn(LD_GENERAL, "[*] Parsed %s guardfraction '%s' for '%s'.",
+ is_consensus ? "consensus" : "vote",
+ guardfraction_str, rs->nickname);
+
+ if (!is_consensus) { /* We are parsing a vote */
+ vote_rs->status.guardfraction_percentage = guardfraction;
+ vote_rs->status.has_guardfraction = 1;
+ } else {
+ /* We are parsing a consensus. Only apply guardfraction to guards. */
+ if (rs->is_possible_guard) {
+ rs->guardfraction_percentage = guardfraction;
+ rs->has_guardfraction = 1;
+ } else {
+ log_warn(LD_BUG, "Got GuardFraction for non-guard %s. "
+ "This is not supposed to happen. Not applying. ", rs->nickname);
+ }
+ }
+
+ return 0;
+}
+
/** Given a string at *<b>s</b>, containing a routerstatus object, and an
* empty smartlist at <b>tokens</b>, parse and return the first router status
* object in the string, and advance *<b>s</b> to just after the end of the
@@ -1994,6 +2054,11 @@ routerstatus_parse_entry_from_string(memarea_t *area,
vote->has_measured_bws = 1;
} else if (!strcmpstart(tok->args[i], "Unmeasured=1")) {
rs->bw_is_unmeasured = 1;
+ } else if (!strcmpstart(tok->args[i], "GuardFraction=")) {
+ if (routerstatus_parse_guardfraction(tok->args[i],
+ vote, vote_rs, rs) < 0) {
+ goto err;
+ }
}
}
}
diff --git a/src/or/routerparse.h b/src/or/routerparse.h
index 18a7d25..fc21cb1 100644
--- a/src/or/routerparse.h
+++ b/src/or/routerparse.h
@@ -85,5 +85,12 @@ int rend_parse_introduction_points(rend_service_descriptor_t *parsed,
size_t intro_points_encoded_size);
int rend_parse_client_keys(strmap_t *parsed_clients, const char *str);
+#ifdef ROUTERPARSE_PRIVATE
+STATIC int routerstatus_parse_guardfraction(const char *guardfraction_str,
+ networkstatus_t *vote,
+ vote_routerstatus_t *vote_rs,
+ routerstatus_t *rs);
+#endif
+
#endif
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