Prop 209: Add path bias counts for timeouts and other mechanisms.

Turns out there's more than one way to block a tagged circuit.

This seems to successfully handle all of the normal exit circuits. Hidden
services need additional tweaks, still.

src/or/circuitbuild.c

@@ -1103,6 +1103,21 @@ pathbias_get_mult_factor(const or_options_t *options)
                                 pathbias_get_scale_factor(options));
 }
 
+/**
+ * If this parameter is set to a true value (default), we use the
+ * successful_circuits_closed. Otherwise, we use the success_count.
+ */
+static int
+pathbias_use_close_counts(const or_options_t *options)
+{
+#define DFLT_PATH_BIAS_USE_CLOSE_COUNTS 1
+  if (options->PathBiasUseCloseCounts >= 0)
+    return options->PathBiasUseCloseCounts;
+  else
+    return networkstatus_get_param(NULL, "pb_useclosecounts",
+                                DFLT_PATH_BIAS_USE_CLOSE_COUNTS, 0, 1);
+}
+
 /**
  * Convert a Guard's path state to string.
  */
@@ -1347,6 +1362,94 @@ pathbias_count_success(origin_circuit_t *circ)
   }
 }
 
+/**
+ * Count a successfully closed circuit.
+ */
+void
+pathbias_count_successful_close(origin_circuit_t *circ)
+{
+  entry_guard_t *guard = NULL;
+  if (!pathbias_should_count(circ)) {
+    return;
+  }
+
+  guard = entry_guard_get_by_id_digest(circ->base_.n_chan->identity_digest);
+   
+  if (guard) {
+    /* In the long run: circuit_success ~= successful_circuit_close + 
+     *                                     circ_failure + stream_failure */
+    guard->successful_circuits_closed++;
+    entry_guards_changed();
+  } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
+   /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
+    * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
+    * No need to log that case. */
+    log_info(LD_BUG,
+        "Successfully closed circuit has no known guard. "
+        "Circuit is a %s currently %s",
+        circuit_purpose_to_string(circ->base_.purpose),
+        circuit_state_to_string(circ->base_.state));
+  }
+}
+
+/**
+ * Count a circuit that fails after it is built, but before it can 
+ * carry any traffic.
+ *
+ * This is needed because there are ways to destroy a
+ * circuit after it has successfully completed. Right now, this is
+ * used for purely informational/debugging purposes.
+ */
+void
+pathbias_count_collapse(origin_circuit_t *circ)
+{
+  entry_guard_t *guard = NULL;
+  if (!pathbias_should_count(circ)) {
+    return;
+  }
+
+  guard = entry_guard_get_by_id_digest(circ->base_.n_chan->identity_digest);
+    
+  if (guard) {
+    guard->collapsed_circuits++;
+    entry_guards_changed();
+  } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
+   /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
+    * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
+    * No need to log that case. */
+    log_info(LD_BUG,
+        "Destroyed circuit has no known guard. "
+        "Circuit is a %s currently %s",
+        circuit_purpose_to_string(circ->base_.purpose),
+        circuit_state_to_string(circ->base_.state));
+  }
+}
+
+void
+pathbias_count_unusable(origin_circuit_t *circ)
+{
+  entry_guard_t *guard = NULL;
+  if (!pathbias_should_count(circ)) {
+    return;
+  }
+
+  guard = entry_guard_get_by_id_digest(circ->base_.n_chan->identity_digest);
+    
+  if (guard) {
+    guard->unusable_circuits++;
+    entry_guards_changed();
+  } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
+   /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
+    * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
+    * No need to log that case. */
+    log_info(LD_BUG,
+        "Stream-failing circuit has no known guard. "
+        "Circuit is a %s currently %s",
+        circuit_purpose_to_string(circ->base_.purpose),
+        circuit_state_to_string(circ->base_.state));
+  }
+}
+
 /**
  * Count timeouts for path bias log messages.
  *
@@ -1367,6 +1470,44 @@ pathbias_count_timeout(origin_circuit_t *circ)
   }
 }
 
+// XXX: DOCDOC
+int
+pathbias_get_closed_count(entry_guard_t *guard)
+{
+  circuit_t *circ = global_circuitlist;
+  int open_circuits = 0;
+
+  /* Count currently open circuits. Give them the benefit of the doubt */
+  for ( ; circ; circ = circ->next) {
+    if (!CIRCUIT_IS_ORIGIN(circ) || /* didn't originate here */
+        circ->marked_for_close) /* already counted */
+      continue;
+
+    if (TO_ORIGIN_CIRCUIT(circ)->path_state == PATH_STATE_SUCCEEDED &&
+        (memcmp(guard->identity, circ->n_chan->identity_digest, DIGEST_LEN)
+         == 0)) {
+      open_circuits++;
+    }
+  }
+
+  return guard->successful_circuits_closed + open_circuits;
+}
+
+/**
+ * This function checks the consensus parameters to decide
+ * if it should return guard->circuit_successes or
+ * guard->successful_circuits_closed.
+ */
+static int
+pathbias_get_success_count(entry_guard_t *guard)
+{
+  if (pathbias_use_close_counts(get_options())) {
+    return pathbias_get_closed_count(guard);
+  } else {
+    return guard->circuit_successes;
+  }
+}
+
 /** Increment the number of times we successfully extended a circuit to
  * 'guard', first checking if the failure rate is high enough that we should
  * eliminate the guard.  Return -1 if the guard looks no good; return 0 if the
@@ -1382,7 +1523,7 @@ entry_guard_inc_first_hop_count(entry_guard_t *guard)
     /* Note: We rely on the < comparison here to allow us to set a 0
      * rate and disable the feature entirely. If refactoring, don't
      * change to <= */
-    if (guard->circuit_successes/((double)guard->first_hops)
+    if (pathbias_get_success_count(guard)/((double)guard->first_hops)
         < pathbias_get_extreme_rate(options)) {
       /* Dropping is currently disabled by default. */
       if (pathbias_get_dropguards(options)) {
@@ -1390,11 +1531,14 @@ entry_guard_inc_first_hop_count(entry_guard_t *guard)
           log_warn(LD_CIRC,
                  "Your Guard %s=%s is failing an extremely large amount of "
                  "circuits. To avoid potential route manipluation attacks, "
-                 "Tor has disabled use of this guard. Success "
-                 "counts are %d/%d, with %d timeouts. For reference, your "
-                 "timeout cutoff is %ld seconds.",
+                 "Tor has disabled use of this guard. "
+                 "Success counts are %d/%d. %d circuits completed, %d "
+                 "were unusable, %d collapsed, and %d timed out. For "
+                 "reference, your timeout cutoff is %ld seconds.",
                  guard->nickname, hex_str(guard->identity, DIGEST_LEN),
-                 guard->circuit_successes, guard->first_hops, guard->timeouts,
+                 pathbias_get_closed_count(guard), guard->first_hops,
+                 guard->circuit_successes, guard->unusable_circuits,
+                 guard->collapsed_circuits, guard->timeouts,
                  (long)circ_times.close_ms/1000);
           guard->path_bias_disabled = 1;
           guard->bad_since = approx_time();
@@ -1406,13 +1550,16 @@ entry_guard_inc_first_hop_count(entry_guard_t *guard)
                  "Your Guard %s=%s is failing an extremely large amount of "
                  "circuits. This could indicate a route manipulation attack, "
                  "extreme network overload, or a bug. "
-                 "Success counts are %d/%d, with %d timeouts. "
-                 "For reference, your timeout cutoff is %ld seconds.",
+                 "Success counts are %d/%d. %d circuits completed, %d "
+                 "were unusable, %d collapsed, and %d timed out. For "
+                 "reference, your timeout cutoff is %ld seconds.",
                  guard->nickname, hex_str(guard->identity, DIGEST_LEN),
-                 guard->circuit_successes, guard->first_hops, guard->timeouts,
+                 pathbias_get_closed_count(guard), guard->first_hops,
+                 guard->circuit_successes, guard->unusable_circuits,
+                 guard->collapsed_circuits, guard->timeouts,
                  (long)circ_times.close_ms/1000);
       }
-    } else if (guard->circuit_successes/((double)guard->first_hops)
+    } else if (pathbias_get_success_count(guard)/((double)guard->first_hops)
                < pathbias_get_warn_rate(options)) {
       if (!guard->path_bias_warned) {
         guard->path_bias_warned = 1;
@@ -1420,25 +1567,31 @@ entry_guard_inc_first_hop_count(entry_guard_t *guard)
                  "Your Guard %s=%s is failing a very large amount of "
                  "circuits. Most likely this means the Tor network is "
                  "overloaded, but it could also mean an attack against "
-                 "you or the potentially the guard itself. Success counts "
-                 "are %d/%d, with %d timeouts. For reference, your timeout "
-                 "cutoff is %ld seconds.",
+                 "you or the potentially the guard itself. "
+                 "Success counts are %d/%d. %d circuits completed, %d "
+                 "were unusable, %d collapsed, and %d timed out. For "
+                 "reference, your timeout cutoff is %ld seconds.",
                  guard->nickname, hex_str(guard->identity, DIGEST_LEN),
-                 guard->circuit_successes, guard->first_hops, guard->timeouts,
+                 pathbias_get_closed_count(guard), guard->first_hops,
+                 guard->circuit_successes, guard->unusable_circuits,
+                 guard->collapsed_circuits, guard->timeouts,
                  (long)circ_times.close_ms/1000);
       }
-    } else if (guard->circuit_successes/((double)guard->first_hops)
+    } else if (pathbias_get_success_count(guard)/((double)guard->first_hops)
                < pathbias_get_notice_rate(options)) {
       if (!guard->path_bias_noticed) {
         guard->path_bias_noticed = 1;
         log_notice(LD_CIRC,
                    "Your Guard %s=%s is failing more circuits than usual. "
                    "Most likely this means the Tor network is overloaded. "
-                   "Success counts are %d/%d, with %d timeouts. For "
+                   "Success counts are %d/%d. %d circuits completed, %d "
+                   "were unusable, %d collapsed, and %d timed out. For "
                    "reference, your timeout cutoff is %ld seconds.",
                    guard->nickname, hex_str(guard->identity, DIGEST_LEN),
-                   guard->circuit_successes, guard->first_hops,
-                   guard->timeouts, (long)circ_times.close_ms/1000);
+                   pathbias_get_closed_count(guard), guard->first_hops,
+                   guard->circuit_successes, guard->unusable_circuits,
+                   guard->collapsed_circuits, guard->timeouts,
+                   (long)circ_times.close_ms/1000);
       }
     }
   }
@@ -1456,13 +1609,20 @@ entry_guard_inc_first_hop_count(entry_guard_t *guard)
                guard->circuit_successes, guard->first_hops, mult_factor,
                scale_factor, guard->nickname, hex_str(guard->identity,
                DIGEST_LEN));
+
       guard->first_hops *= mult_factor;
       guard->circuit_successes *= mult_factor;
       guard->timeouts *= mult_factor;
+      guard->successful_circuits_closed *= mult_factor;
+      guard->collapsed_circuits *= mult_factor;
+      guard->unusable_circuits *= mult_factor;
 
       guard->first_hops /= scale_factor;
       guard->circuit_successes /= scale_factor;
       guard->timeouts /= scale_factor;
+      guard->successful_circuits_closed /= scale_factor;
+      guard->collapsed_circuits /= scale_factor;
+      guard->unusable_circuits /= scale_factor;
     }
   }
   guard->first_hops++;

src/or/circuitbuild.h

@@ -56,6 +56,12 @@ const node_t *choose_good_entry_server(uint8_t purpose,
 double pathbias_get_extreme_rate(const or_options_t *options);
 int pathbias_get_dropguards(const or_options_t *options);
 void pathbias_count_timeout(origin_circuit_t *circ);
+void pathbias_count_successful_close(origin_circuit_t *circ);
+void pathbias_count_collapse(origin_circuit_t *circ);
+void pathbias_count_unusable(origin_circuit_t *circ);
+
+typedef struct entry_guard_t entry_guard_t;
+int pathbias_get_closed_count(entry_guard_t *gaurd);
 
 #endif
 

src/or/circuitlist.c

@@ -1347,7 +1347,44 @@ circuit_mark_for_close_(circuit_t *circ, int reason, int line,
     }
     reason = END_CIRC_REASON_NONE;
   }
+  
   if (CIRCUIT_IS_ORIGIN(circ)) {
+    origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
+
+    if (ocirc->path_state == PATH_STATE_SUCCEEDED) {
+      int pathbias_is_normal_close = 1;
+
+      /* FIXME: Is timestamp_dirty the right thing for these two checks? 
+       * Should we use isolation_any_streams_attached instead? */
+      if (!circ->timestamp_dirty) {
+        if (reason & END_CIRC_REASON_FLAG_REMOTE) {
+          /* Unused remote circ close reasons all could be bias */
+          pathbias_is_normal_close = 0;
+          pathbias_count_collapse(ocirc);
+        } else if ((reason & ~END_CIRC_REASON_FLAG_REMOTE)
+                    == END_CIRC_REASON_CHANNEL_CLOSED &&
+                   circ->n_chan->reason_for_closing 
+                    != CHANNEL_CLOSE_REQUESTED) {
+          /* If we didn't close the channel ourselves, it could be bias */
+          /* FIXME: Only count bias if the network is live?
+           * What about clock jumps/suspends? */
+          pathbias_is_normal_close = 0;
+          pathbias_count_collapse(ocirc);
+        }
+      } else if (circ->timestamp_dirty && !ocirc->any_streams_succeeded) {
+        /* Any circuit where there were attempted streams but no successful
+         * streams could be bias */
+        /* FIXME: This may be better handled by limiting the number of retries
+         * per stream? */
+        pathbias_is_normal_close = 0;
+        pathbias_count_unusable(ocirc);
+      }
+
+      if (pathbias_is_normal_close) {
+        pathbias_count_successful_close(ocirc);
+      }
+    }
+
     /* We don't send reasons when closing circuits at the origin. */
     reason = END_CIRC_REASON_NONE;
   }

src/or/config.c

@@ -323,6 +323,7 @@ static config_var_t option_vars_[] = {
   V(PathBiasScaleFactor,         INT,      "-1"),
   V(PathBiasMultFactor,          INT,      "-1"),
   V(PathBiasDropGuards,          BOOL,      "0"),
+  V(PathBiasUseCloseCounts,      BOOL,      "1"),
 
   OBSOLETE("PathlenCoinWeight"),
   V(PerConnBWBurst,              MEMUNIT,  "0"),

src/or/connection_edge.c

@@ -2176,6 +2176,17 @@ connection_ap_handshake_socks_reply(entry_connection_t *conn, char *reply,
      status==SOCKS5_SUCCEEDED ? STREAM_EVENT_SUCCEEDED : STREAM_EVENT_FAILED,
                               endreason);
 
+  /* Flag this stream's circuit as having completed a stream successfully
+   * (for path bias) */
+  if (status == SOCKS5_SUCCEEDED) {
+    if(!conn->edge_.on_circuit ||
+       !CIRCUIT_IS_ORIGIN(conn->edge_.on_circuit)) {
+      log_warn(LD_BUG, "No origin circuit for successful SOCKS stream");
+    } else {
+      TO_ORIGIN_CIRCUIT(conn->edge_.on_circuit)->any_streams_succeeded = 1;
+    }
+  }
+
   if (conn->socks_request->has_finished) {
     log_warn(LD_BUG, "(Harmless.) duplicate calls to "
              "connection_ap_handshake_socks_reply.");

src/or/entrynodes.c

@@ -1021,7 +1021,8 @@ entry_guards_parse_state(or_state_t *state, int set, char **msg)
       digestmap_set(added_by, d, tor_strdup(line->value+HEX_DIGEST_LEN+1));
     } else if (!strcasecmp(line->key, "EntryGuardPathBias")) {
       const or_options_t *options = get_options();
-      unsigned hop_cnt, success_cnt, timeouts;
+      unsigned hop_cnt, success_cnt, timeouts, collapsed, successful_closed,
+               unusable;
 
       if (!node) {
         *msg = tor_strdup("Unable to parse entry nodes: "
@@ -1030,19 +1031,33 @@ entry_guards_parse_state(or_state_t *state, int set, char **msg)
       }
 
       /* First try 3 params, then 2. */
-      if (tor_sscanf(line->value, "%u %u %u", &success_cnt, &hop_cnt,
-                     &timeouts) != 3) {
-        timeouts = 0;
+      // XXX: We want to convert this to floating point before merge
+      /* In the long run: circuit_success ~= successful_circuit_close + 
+       *                                     collapsed_circuits +
+       *                                     unusable_circuits */
+      if (tor_sscanf(line->value, "%u %u %u %u %u %u",
+                  &hop_cnt, &success_cnt, &successful_closed,
+                  &collapsed, &unusable, &timeouts) != 6) {
         if (tor_sscanf(line->value, "%u %u", &success_cnt, &hop_cnt) != 2) {
-          log_warn(LD_GENERAL, "Unable to parse guard path bias info: "
-                 "Misformated EntryGuardPathBias %s", escaped(line->value));
           continue;
         }
+        log_info(LD_GENERAL, "Reading old-style EntryGuardPathBias %s",
+                 escaped(line->value));
+
+        successful_closed = success_cnt;
+        timeouts = 0;
+        collapsed = 0;
+        unusable = 0;
       }
 
       node->first_hops = hop_cnt;
       node->circuit_successes = success_cnt;
+
+      node->successful_circuits_closed = successful_closed;
       node->timeouts = timeouts;
+      node->collapsed_circuits = collapsed;
+      node->unusable_circuits = unusable;
+
       log_info(LD_GENERAL, "Read %u/%u path bias for node %s",
                node->circuit_successes, node->first_hops, node->nickname);
       /* Note: We rely on the < comparison here to allow us to set a 0
@@ -1180,8 +1195,13 @@ entry_guards_update_state(or_state_t *state)
       if (e->first_hops) {
         *next = line = tor_malloc_zero(sizeof(config_line_t));
         line->key = tor_strdup("EntryGuardPathBias");
-        tor_asprintf(&line->value, "%u %u %u",
-                     e->circuit_successes, e->first_hops, e->timeouts);
+        /* In the long run: circuit_success ~= successful_circuit_close + 
+         *                                     collapsed_circuits +
+         *                                     unusable_circuits */
+        tor_asprintf(&line->value, "%u %u %u %u %u %u",
+                     e->first_hops, e->circuit_successes,
+                     pathbias_get_closed_count(e), e->collapsed_circuits,
+                     e->unusable_circuits, e->timeouts);
         next = &(line->next);
       }
 

src/or/entrynodes.h

@@ -51,7 +51,15 @@ typedef struct entry_guard_t {
   unsigned first_hops; /**< Number of first hops this guard has completed */
   unsigned circuit_successes; /**< Number of successfully built circuits using
                                * this guard as first hop. */
-  unsigned timeouts; /**< Number of 'right-censored' timeouts for this guard.*/
+  unsigned successful_circuits_closed; /**< Number of circuits that carried
+                                        * streams successfully. */
+  unsigned collapsed_circuits; /**< Number of fully built circuits that were
+                                 * remotely closed before any streams were
+                                 * attempted. */
+  unsigned unusable_circuits; /**< Number of circuits for which streams were 
+                                *  attempted, but none succeeded. */
+  unsigned timeouts; /**< Number of 'right-censored' circuit timeouts for this
+                       * guard. */
 } entry_guard_t;
 
 entry_guard_t *entry_guard_get_by_id_digest(const char *digest);

src/or/or.h

@@ -2872,6 +2872,13 @@ typedef struct origin_circuit_t {
    */
   unsigned int isolation_any_streams_attached : 1;
 
+  /**
+   * Did any SOCKS streams actually succeed on this circuit?
+   *
+   * XXX: We probably also need to set this for intro other hidserv circs..
+   */
+  unsigned int any_streams_succeeded : 1;
+
   /** A bitfield of ISO_* flags for every isolation field such that this
    * circuit has had streams with more than one value for that field
    * attached to it. */
@@ -3790,6 +3797,7 @@ typedef struct {
   int PathBiasScaleThreshold;
   int PathBiasScaleFactor;
   int PathBiasMultFactor;
+  int PathBiasUseCloseCounts;
   /** @} */
 
   int IPv6Exit; /**< Do we support exiting to IPv6 addresses? */