Add a MinTimeToReportBandwidth option; make it 0 for testing networks.

This option changes the time for which a bandwidth measurement period
must have been in progress before we include it when reporting our
observed bandwidth in our descriptors.  Without this option, we only
consider a time period towards our maximum if it has been running
for a full day.  Obviously, that's unacceptable for testing
networks, where we'd like to get results as soon as possible.

For non-testing networks, I've put a (somewhat arbitrary) 2-hour
minimum on the option, since there are traffic analysis concerns
with immediate reporting here.

Closes #40337.

4 files changed, 20 insertions, 0 deletions

diff --git a/src/app/config/config.c b/src/app/config/config.c
index fa74907b3d..9011f36735 100644
--- a/src/app/config/config.c
+++ b/src/app/config/config.c
@@ -563,6 +563,7 @@ static const config_var_t option_vars_[] = {
   V(MaxUnparseableDescSizeToLog, MEMUNIT, "10 MB"),
   VPORT(MetricsPort),
   V(MetricsPortPolicy,           LINELIST, NULL),
+  V(MinTimeToReportBandwidth,    INTERVAL, "1 day"),
   VAR("MyFamily",                LINELIST, MyFamily_lines,       NULL),
   V(NewCircuitPeriod,            INTERVAL, "30 seconds"),
   OBSOLETE("NamingAuthoritativeDirectory"),
@@ -3711,6 +3712,13 @@ options_validate_cb(const void *old_options_, void *options_, char **msg)
     options->HeartbeatPeriod = MIN_HEARTBEAT_PERIOD;
   }
 
+  if (options->MinTimeToReportBandwidth < MIN_MIN_TIME_TO_REPORT_BW &&
+      !options->TestingTorNetwork) {
+    log_warn(LD_CONFIG, "MinTimeToReportBandwidth is too short; "
+             "raising to %d seconds.", MIN_MIN_TIME_TO_REPORT_BW);
+    options->MinTimeToReportBandwidth = MIN_MIN_TIME_TO_REPORT_BW;
+  }
+
   if (options->KeepalivePeriod < 1)
     REJECT("KeepalivePeriod option must be positive.");
 
diff --git a/src/app/config/config.h b/src/app/config/config.h
index e95ef4a728..74e6942eb5 100644
--- a/src/app/config/config.h
+++ b/src/app/config/config.h
@@ -24,6 +24,13 @@
  * expose more information than we're comfortable with. */
 #define MIN_HEARTBEAT_PERIOD (30*60)
 
+/**
+ * Lowest allowable value for MinTimeToReportBandwidth on a non-testing
+ * network; if this is too low we might report detail that is too
+ * fine-grained.
+ **/
+#define MIN_MIN_TIME_TO_REPORT_BW (2*60*60)
+
 /** Maximum default value for MaxMemInQueues, in bytes. */
 #if SIZEOF_VOID_P >= 8
 #define MAX_DEFAULT_MEMORY_QUEUE_SIZE (UINT64_C(8) << 30)
diff --git a/src/app/config/or_options_st.h b/src/app/config/or_options_st.h
index 4364f145ed..efecc85d66 100644
--- a/src/app/config/or_options_st.h
+++ b/src/app/config/or_options_st.h
@@ -1082,6 +1082,10 @@ struct or_options_t {
   /** List of policy allowed to query the Metrics port. */
   struct config_line_t *MetricsPortPolicy;
 
+  /** How far must we be into the current bandwidth-measurement period to
+   * report bandwidth observations from this period? */
+  int MinTimeToReportBandwidth;
+
   /**
    * Configuration objects for individual modules.
    *
diff --git a/src/app/config/testnet.inc b/src/app/config/testnet.inc
index 00b307782b..527e0d00b1 100644
--- a/src/app/config/testnet.inc
+++ b/src/app/config/testnet.inc
@@ -19,6 +19,7 @@
 { "TestingV3AuthInitialDistDelay", "20 seconds" },
 { "TestingAuthDirTimeToLearnReachability", "0 minutes" },
 { "MinUptimeHidServDirectoryV2", "0 minutes" },
+{ "MinTimeToReportBandwidth", "0 seconds" },
 { "TestingServerDownloadInitialDelay", "0" },
 { "TestingClientDownloadInitialDelay", "0" },
 { "TestingServerConsensusDownloadInitialDelay", "0" },