How to access Tor's request error logs?

Question

There is the following non working URL: http://jamie3vkiwibfiwucd6vxijskbhpjdyajmzeor4mc4i7yopvpo4p7cyd.onion/

When I open Tor binary and route a GET request through it I receive:

socks connect tcp 127.0.0.1:9050->jamie3vkiwibfiwucd6vxijskbhpjdyajmzeor4mc4i7yopvpo4p7cyd.onion:80: unknown error host unreachable

However, when I open Tor Browser and do the same, I receive more detailed information:

Details: 0xF0 — The requested onion service descriptor can't be found on the hashring and therefore the service is not reachable by the client.

How can I access the same level of verbosity for a standalone Tor binary?

Answer 1

The Tor Browser has more detailed information because it uses the ExtendedErrors configuration for the SocksPort in the torrc file. For example in your torrc file, you can use SocksPort 9050 ExtendedErrors to enable this feature. When you connect to tor's socks proxy, it will then return these non-standard error codes, although most client applications (such as curl) won't know what they mean. Overview of the possible error codes are below, see the man page for details:

X'F0' Onion Service Descriptor Can Not be Found
X'F1' Onion Service Descriptor Is Invalid
X'F2' Onion Service Introduction Failed
X'F3' Onion Service Rendezvous Failed
X'F4' Onion Service Missing Client Authorization
X'F5' Onion Service Wrong Client Authorization
X'F6' Onion Service Invalid Address
X'F7' Onion Service Introduction Timed Out