tor/doc/TODO

$Id$
Legend:
SPEC!!  - Not specified
SPEC    - Spec not finalized
N       - nick claims
R       - arma claims
P       - phobos claims
        - Not done
        * Top priority
        . Partially done
        o Done
        D Deferred
        X Abandoned

Non-Coding, Soon:
N - Mark up spec; note unclear points about servers
N - Mention controller libs someplace.
  D FAQ entry: why gnutls is bad/not good for tor
P - flesh out the rest of the section 6 of the faq
P - gather pointers to livecd distros that include tor
R . more pictures from ren. he wants to describe the tor handshake, i want to
    talk about hidden services.
NR- write a spec appendix for 'being nice with tor'
  - tor-in-the-media page
  - Remove need for HACKING file.

Website:
  - we need to merge documentation and support
  - and pare it down
  - and merge developers into documentation too
  - or at least, remove developers from the title bar
  - and remove home and make the "Tor" picture be the link to home.
  - put the logo on the website, in source form, so people can put it on
    stickers directly, etc.

for 0.1.1.x:
N - if they're trying to be a tor server and they're running
     win 98 or win me, give them a message talking about The Bug.

R . Rename 'helper' to 'guard'.

N - Display the reasons in 'destroy' and 'truncated' cells under some
    circumstances?

N . Directory changes
    . Client side:
      - Do we want to rate-limit downloads of each identity, or do something
        else to download even less?
      - Do we want to refrain from downloading non-running or non-verified
        descriptors? This is potentially dangerous.
    - Non-directories don't need to keep descriptors in memory.

R - Christian Grothoff's attack of infinite-length circuit.
    the solution is to have a separate 'extend-data' cell type
    which is used for the first N data cells, and only
    extend-data cells can be extend requests.
    - Specify, including thought about
    - Implement

R - When we connect to a Tor server, it sends back a signed cell listing
    the IP it believes it is using. Use this to block dvorak's attack.
    Also, this is a fine time to say what time you think it is.
    - Verify that a new cell type is okay with deployed codebase
    - Specify
    - Implement

R - clients prefer to avoid exit nodes for non-exit path positions.

  - find 10 dirservers.
    - What are criteria to be a dirserver?  Write a policy.

  - the tor client can do the "automatic proxy config url" thing?

Deferred from 0.1.1.x:

  - Automatically determine what ports are reachable and start using
    those, if circuits aren't working and it's a pattern we recognize
    ("port 443 worked once and port 9001 keeps not working").

N - Should router info have a pointer to routerstatus?
    - We should at least do something about the duplicated fields.

N . Additional controller features
      - change circuit status events to give more details, like purpose,
        whether they're internal, when they become dirty, when they become
        too dirty for further circuits, etc.
R       - What do we want here, exactly?
N       - Specify and implement it.
      - Change stream status events analogously.
R       - What do we want here, exactly?
N       - Specify and implement it.
      - Make other events "better".
      - Change stream status events analogously.
R       - What do we want here, exactly?
N       - Specify and implement it.
      - Make other events "better" analogously
R       - What do we want here, exactly?
N       - Specify and implement it.
      . Expose more information via getinfo:
        - import and export rendezvous descriptors
        - Review all static fields for additional candidates
      - Allow EXTENDCIRCUIT to unknown server.
      - We need some way to adjust server status, and to tell tor not to
        download directories/network-status, and a way to force a download.
      - It would be nice to request address lookups from the controller
        without using SOCKS.
      - Make everything work with hidden services

  X switch accountingmax to count total in+out, not either in or
    out. it's easy to move in this direction (not risky), but hard to
    back out if we decide we prefer it the way it already is. hm.

  - cpu fixes:
    - see if we should make use of truncate to retry
R   - kill dns workers more slowly

  . Directory changes
    . Some back-out mechanism for auto-approval
      - a way of rolling back approvals to before a timestamp
        - Consider minion-like fingerprint file/log combination.

    - config option to publish what ports you listen on, beyond
      ORPort/DirPort.  It should support ranges and bit prefixes (?) too.
      - Parse this.
      - Relay this in networkstatus.

  - packaging and ui stuff:
    . multiple sample torrc files
    - uninstallers
      . for os x
    . figure out how to make nt service stuff work?
      . Document it.
    . Add version number to directory.
N   - Vet all pending installer patches
      - Win32 installer plus privoxy, sockscap/freecap, etc.
      - Vet win32 systray helper code

  - document:
    - torcp needs more attention in the tor-doc-win32.
    - recommend gaim.
    - unrecommend IE because of ftp:// bug.
    - torrc.complete.in needs attention?

  - Bind to random port when making outgoing connections to Tor servers,
    to reduce remote sniping attacks.
  - Have new people be in limbo and need to demonstrate usefulness
    before we approve them.
  - Clients should estimate their skew as median of skew from servers
    over last N seconds.
  - Security
    - Alices avoid duplicate class C nodes.
    - Analyze how bad the partitioning is or isn't.

  . Update the hidden service stuff for the new dir approach.
    - switch to an ascii format, maybe sexpr?
    - authdirservers publish blobs of them.
    - other authdirservers fetch these blobs.
    - hidserv people have the option of not uploading their blobs.
    - you can insert a blob via the controller.
    - and there's some amount of backwards compatibility.
    - teach clients, intro points, and hidservs about auth mechanisms.
    - come up with a few more auth mechanisms.

  . Come up with a coherent strategy for bandwidth buckets and TLS. (The
    logic for reading from TLS sockets is likely to overrun the bandwidth
    buckets under heavy load.  (Really, the logic was never right in the
    first place.)  Also, we should audit all users of get_pending_bytes().)
      - Make it harder to circumvent bandwidth caps: look at number of bytes
        sent across sockets, not number sent inside TLS stream.

  - Make router_is_general_exit() a bit smarter once we're sure what it's for.

  - Directory "helper".

  - rewrite how libevent does select() on win32 so it's not so very slow.
  - Write limiting; separate token bucket for write
  - Audit everything to make sure rend and intro points are just as likely to
    be us as not.
  - Do something to prevent spurious EXTEND cells from making middleman
    nodes connect all over.  Rate-limit failed connections, perhaps?

Future version:
  - Limit to 2 dir, 2 OR, N SOCKS connections per IP.
  - Handle full buffers without totally borking
  - Rate-limit OR and directory connections overall and per-IP and
    maybe per subnet.
  - Hold-open-until-flushed now works by accident; it should work by
    design.
  - DoS protection: TLS puzzles, public key ops, bandwidth exhaustion.
    - Specify?
  - tor-resolve script should use socks5 to get better error messages.
  - make min uptime a function of the available choices (say, choose 60th
    percentile, not 1 day.)
  - Track uptime as %-of-time-up, as well as time-since-last-down.
  - hidserv offerers shouldn't need to define a SocksPort
    * figure out what breaks for this, and do it.
  - auth mechanisms to let hidden service midpoint and responder filter
    connection requests.
  - Relax clique assumptions.
  X start handling server descriptors without a socksport?
  - tor should be able to have a pool of outgoing IP addresses
    that it is able to rotate through. (maybe)

Blue-sky:
  - Patch privoxy and socks protocol to pass strings to the browser.
  - Standby/hotswap/redundant hidden services.
  - Robust decentralized storage for hidden service descriptors.
  - The "China problem"
  - Allow small cells and large cells on the same network?
  - Cell buffering and resending. This will allow us to handle broken
    circuits as long as the endpoints don't break, plus will allow
    connection (tls session key) rotation.
  - Implement Morphmix, so we can compare its behavior, complexity, etc.
  - Other transport. HTTP, udp, rdp, airhook, etc. May have to do our own
    link crypto, unless we can bully openssl into it.
  - Need a relay teardown cell, separate from one-way ends.
    (Pending a user who needs this)
  - Handle half-open connections: right now we don't support all TCP
    streams, at least according to the protocol. But we handle all that
    we've seen in the wild.
    (Pending a user who needs this)