
             Protocol of CollecTor's File Structure
                            DRAFT

1.0 Introduction

   This protocol describes the file structure of the data offered by
   CollecTor mirrors.  The description of the data contained in the
   structure is not part of this protocol and can be found on the
   main page of a CollecTor instance, e.g. https://collector.torproject.org

   CollecTor's data resides in three top elements:

   * archive folder
   * index files
   * recent folder

   These can be located anywhere on the providing systems memory, permanent
   or in-memory.  As long as they can be accesses from the root folder of
   the web-interface, i.e.

     https://collector.someinstance.org/archive
     https://collector.someinstance.org/index.json*
     https://collector.someinstance.org/recent

   The fourth file system structure that is part of the protocol is the
   output directory (in the following referred to as 'out'), which is not
   directly visible to CollecTor's clients.  This directory is the place
   for internal storage and its file system structure is later contained
   in the provided tar-balls with archived data.

   The following sections describe the substructure of the storage locations.

2.0 The 'archive' Folder

   The 'archive' folder contains the Tor network history as compressed
   tarballs.

2.1 Immediate Subfolders of 'archive'

   The top structure of 'archive' is comprised of

   * bridge-descriptors
   * bridge-pool-assignments
   * exit-lists
   * relay-descriptors
   * torperf

   The substructure of these folders differs depending on their content.

2.2 'bridge-pool-assignments', 'exit-lists', and 'torperf' below 'archive'

   'bridge-pool-assignments', 'exit-lists', and 'torperf' directly contain the
   compressed tar-balls named according to the following rules:

   marker DASH year DASH month DOT TAR DOT compression-type

   DASH is the "-" symbol.
   DOT a dot ".".
   TAR is the string "tar".

   'marker' is the either 'bridge-pool-assignments', 'torperf', or 'exit-lists'.
   'year' and 'month' are derived from the published dates (bridge pool
   assignments), measurement dates (torperf), or download dates (exit lists) of
   the contained data.
   The 'compression-type' is one element of "xz", "gz", "bz2", or "zip".  The
   current default compression type is set to "xz".

2.3 'bridge-descriptors' below 'archive'

   'bridge-descriptors' contains the following subdirectories:

   * extra-infos
   * server-descriptors
   * statuses

   These directories contain compressed tar-balls of the respective descriptors.
   The compressed tar-balls are named in the following way:

   BRIDGE DASH marker DASH year DASH month DOT TAR DOT compression-type

   BRIDGE is the string "bridge".

   'marker' is one of 'extra-infos', 'server-descriptors', or 'statuses'.
   'year' and 'month' are derived from the published dates of the contained
   data.

2.4 'relay-descriptors' below 'archive'

   'relay-descriptors' contains  the following substructure:

   * consensuses
   * extra-infos
   * microdescs
   * server-descriptors
   * statuses
   * tor
   * votes
   * certs.tar.xz

   'consensuses', 'extra-infos', 'microdescs', 'server-descriptors',
   'statuses', 'tor', and 'votes' contain compressed tar-balls of the
   respective descriptors.
   The compressed tar-balls are named in the following way:

   marker DASH year DASH month DOT TAR DOT compression-type

   'marker' is one of    'consensuses', 'extra-infos', 'microdescs',
   'server-descriptors', 'statuses', 'tor', or 'votes'
   'year' and 'month' are derived from different dates found in the data:

   * for consensuses, microdescs, and votes from the valid-after dates,
   * for extra-infos, server-descriptors, statuses, and tor from the
     published dates.

3.0 Index Files

   The index.json file and its compressed versions of various types are
   contained under the web-root of the main CollecTor instance.
   Future versions of this protocol might move these files to a separate
   'index' folder.

4.0 The 'recent' folder

   'recent' provides data from the last 72 hours in the following
   subfolders:

   * bridge-descriptors
   * exit-lists
   * relay-descriptors
   * torperf

4.1 'exit-lists' and 'torperf' below 'recent'

4.1.1
   'exit-lists' and 'torperf' directly contain the data files.
   The exit-list files are named

   year DASH month DASH day DASH hour DASH minute DASH second

   Where these are derived from the download time (exit lists) or measurement
   time (torperf).

4.1.2
   'torperf' contains files named

   source DASH kilobytes DASH year DASH month DASH day DOT extension

   Where 'source' is defined by the CollecTor instance and can
   be mapped to a URL.  'year', 'month', and 'day' are taken from
   the download date.  'extension' is 'tpf'.

4.2 'bridge-descriptors' below 'recent'

   'bridge-descriptors' contains the following subdirectories:

   * extra-infos
   * server-descriptors
   * statuses

4.2.1
   'extra-infos' and 'server-descriptors' contain data files named
   in the following way:

   year DASH month DASH day DASH hour DASH minute DASH second
   DASH marker

   Where 'marker' is one of the strings "extra-infos" or "server-descriptors".
   All time related values are derived from the download time.

4.2.2
   'statuses' contains data files named

   year month day DASH hour minute second DASH fingerprint

   All time related values are derived from the published time and
   'fingerprint' is the fingerprint of the providing bridge
   authority.

4.3 'relay-descriptors' below 'recent'

   'relay-descriptors' contains  the following substructure:

   * consensuses
   * extra-infos
   * microdescs
   * server-descriptors
   * votes

4.3.1
   'consensuses' contains consensus documents named according:

   year DASH month DASH day DASH hour DASH minute DASH second
   DASH CONSENSUS

   Where CONSENSUS is the string "consensus" and all time related
   values are derived from the valid-after dates.

4.3.2
   'extra-infos' and 'server-descriptors' contain data files as
   the corresponding folder described in section 4.2.1.

4.3.3
   'votes' contains files named

   year DASH month DASH day DASH hour DASH minute DASH second
   DASH VOTE DASH fingerprint DASH digest

   Where VOTE is the string "vote" and all time related
   values are derived from the valid-after dates. 'fingerprint'
   is the fingerprint of the authority and 'digest' is the SHA1
   digest of the authority's medium term signing key.

4.3.4
   'microdescs' contains the subfolders

   * consensus-microdesc
   * micro

   'consensus-microdesc' contains files named

   year DASH month DASH day DASH hour DASH minute DASH second
   DASH CONSENSUSMICRO

   Where CONSENSUSMICRO is the string "consensus-microdesc" and
   all time related values are derived from the valid-after dates.

4.3.5
   'micro' serves files named

   year DASH month DASH day DASH hour DASH minute DASH second
   DASH MICRO

   Where MICRO is the string "micro" and all time related values
   are derived from the valid-after dates of the referencing microdesc
   consensus.

5.0 The Tar-ball's Directory Structure and the Internal Structure

   The 'out' directory is the internal storage that is used for
   preparing tar-balls.  So, the following structures occur also
   partially in the tars that are currently prepared per month.

   The top level of subdirectories is

   * bridge-descriptors
   * exit-lists
   * relay-descriptors
   * torperf

   (There has been a fifth subdirectory 'bridge-pool-assignments' which has been
   removed when CollecTor stopped collecting those descriptors.  However, it's
   structure can still be found in the tarballs.)

5.1 'exit-lists' and 'torperf' Tars

5.1.1
   'exit-lists' and 'torperf' tars are taken from the following
   subdirectory structure

   year SEP month SEP day

   Where SEP is the path separator (usually *nix type "/") and
   year, month, and day are derived from the download dates (exit lists) or
   measurement dates (torperf).
   Files insides the day directory level are named according to the
   rules in 4.1.1 and 4.1.2.

   Thus, monthly tars are named according to section 2.2 and contain
   the following structure

   marker DASH year DASH month SEP day

   Where 'marker' stands for the strings "torperf" or "exit-list".

5.1.2
   The 'torperf' directory also contains summary files named

   source DASH amount DOT extension

   Where 'source' is the data source defined in the CollecTor instance,
   amount is a number with appended "kb" or "mb", and 'extension' is
   either "data" or "extradata".

5.2 'bridge-descriptors' below 'out'

   'bridge-descriptors' contains the following subdirectories:

   * extra-infos
   * server-descriptors
   * statuses

5.2.1
   'extra-infos' and 'server-descriptors' have the following
   subdirectory structure

   year SEP month SEP first SEP second

   Where year is derived from the published date.
   'first' and 'second' are the first and second symbol from the
   router-digest, which also serves as the filename for the files
   in the 'second' level directories.

   Tars are named according to section 2.3 and have the following
   substructure using the definitions from 2.3:

   BRIDGE DASH marker DASH year DASH month SEP first SEP second

5.2.2
   'statuses' have a different substructure

   year SEP month SEP day

   Where 'year', 'month', and 'day' are derived from the published dates.
   Files insides the 'day' directory level are named according to the
   rules in 4.2.2.

   The tars are named as in 2.3 with the substructure

   BRIDGE DASH STATUSES DASH year DASH month SEP day

   Where STATUSES is the string "statuses".

5.3 'relay-descriptors' below 'out'

   'relay-descriptors' contains  the following substructure:

   * certs
   * consensus
   * extra-info
   * microdesc
   * server-descriptor
   * vote

5.3.1
   'certs' contains certificate files named

   fingerprint DASH year DASH month DASH day DASH hour DASH minute DASH second

   All time related values are derived from the key-published time and
   'fingerprint' is the fingerprint of the authority.

5.3.2
   'consensus' and 'vote' contain the subdirectory structure

   year SEP month SEP day

   Where the time related values are taken from the valid-after dates.

   'extra-info' and 'server-descriptor' follow the naming and subdirectory
   structure as described in 5.2.1.  'consensus' and 'vote' tars use the
   substructure of 'statuses' as described in 5.2.2.

5.3.3
   'microdesc' has a more complex subdirectory structure

   year SEP month

   Where the time related values are taken from the valid-after dates.
   Inside the 'month' folders are two directories

   * consensus-microdesc
   * micro

5.3.4
   'consensus-microdesc' contains 'day' subdirectories derived from the
   valid-after dates and files named according to 4.3.4.

   'micro' follows the subdirectory structure of

   first SEP second

   Where year is derived from the published date.
   'first' and 'second' are the first and second symbol from the SHA-256
   digest, which also serves as the filename for the files
   in the 'second' level directories.

   The monthly tars are named according to 2.4 and contain

   MICRODESCS DASH year DASH month

   and below the subdirectories of 'micro' and 'consensus-microdescs'.


