How can I find the meaning of the messages in Tor's debugging log?

Question

How can I know what does this message mean:

Jun 01 18:28:23.000 [debug] circuit_build_times_add_time(): Adding circuit build time 525

Note:

I'm using Log debug file TorMonitor in my torrc to view Tor logs.

Answer 1

As it says it's debug message, so normally you should ignore or disable any debugs.

For that kind of messages I don't think you can find reasonable meaning without Googling it or checking the source code (svn, git), because these messages are mainly for developers.

If you think it could be a bug, check at Tor bug tracker.

The code responsible for that specific message is:

/**
 * Add a new build time value <b>time</b> to the set of build times. Time
 * units are milliseconds.
 *
 * circuit_build_times <b>cbt</b> is a circular array, so loop around when
 * array is full.
 */
int
circuit_build_times_add_time(circuit_build_times_t *cbt, build_time_t time)
{
  if (time <= 0 || time > CBT_BUILD_TIME_MAX) {
    log_warn(LD_BUG, "Circuit build time is too large (%u)."
                      "This is probably a bug.", time);
    tor_fragile_assert();
    return -1;
  }

log_debug(LD_CIRC, "Adding circuit build time %u", time);
...

So the top comment above the function name should be already some help.

---

As far as I know the circuit build times checkings are mainly to protect Tor hidden services from botnet abuse.

Read more:

• Short Paper: Challenges in protecting Tor hidden services from botnet abuse