# Stem Docs

## Extrainfo Descriptor

Parsing for Tor extra-info descriptors. These are published by relays whenever their server descriptor is published and have a similar format. However, unlike server descriptors these don’t contain information that Tor clients require to function and as such aren’t fetched by default.

Defined in section 2.1.2 of the dir-spec, extra-info descriptors contain interesting but non-vital information such as usage statistics. Tor clients cannot request these documents for bridges.

Extra-info descriptors are available from a few sources…

- If you have ‘DownloadExtraInfo 1’ in your torrc…

> - control port via ‘GETINFO extra-info/digest/*’ queries

> - the ‘cached-extrainfo’ file in tor’s data directory

- Archived descriptors provided by CollecTor.

- Directory authorities and mirrors via their DirPort.

Module Overview:

    ExtraInfoDescriptor - Tor extra-info descriptor.
      |- RelayExtraInfoDescriptor - Extra-info descriptor for a relay.
      |- BridgeExtraInfoDescriptor - Extra-info descriptor for a bridge.
      |
      +- digest - calculates the upper-case hex digest value for our content

`stem.descriptor.extrainfo_descriptor.``DirResponse`(enum)

  Enumeration for known statuses for ExtraInfoDescriptor’s dir_*_responses.

  DirResponse | Description
  --- | ---
  OK | network status requests that were answered
  NOT_ENOUGH_SIGS | network status wasn’t signed by enough authorities
  UNAVAILABLE | requested network status was unavailable
  NOT_FOUND | requested network status was not found
  NOT_MODIFIED | network status unmodified since If-Modified-Since time
  BUSY | directory was busy

`stem.descriptor.extrainfo_descriptor.``DirStat`(enum)

  Enumeration for known stats for ExtraInfoDescriptor’s dir_*_direct_dl and dir_*_tunneled_dl.

  DirStat | Description
  --- | ---
  COMPLETE | requests that completed successfully
  TIMEOUT | requests that didn’t complete within a ten minute timeout
  RUNNING | requests still in process when measurement’s taken
  MIN | smallest rate at which a descriptor was downloaded in B/s
  MAX | largest rate at which a descriptor was downloaded in B/s
  D1-4 and D6-9 | rate of the slowest x/10 download rates in B/s
  Q1 and Q3 | rate of the slowest and fastest quarter download rates in B/s
  MD | median download rate in B/s