tor/doc/TODO
Nick Mathewson 97b61b9889 r12519@Kushana: nickm | 2007-03-10 00:57:01 -0500
Remove a redundant check for event.h; add some comments, and reformat.


svn:r9790
2007-03-10 07:38:42 +00:00

442 lines
21 KiB
Plaintext

$Id$
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 Deferrable
D Deferred
X Abandoned
Documentation and testing on 0.1.2.x-final series
N - Test guard unreachable logic; make sure that we actually attempt to
connect to guards that we think are unreachable from time to time.
Make sure that we don't freak out when the network is down.
. Forward compatibility fixes
N - Hack up a client that gives out weird/no certificates, so we can
test to make sure that this doesn't cause servers to crash.
NR. Write path-spec.txt
- Docs
- Tell people about OSX Uninstaller
- Quietly document NT Service options
- More prominently, we should have a recommended apps list.
- recommend gaim.
- unrecommend IE because of ftp:// bug.
N - we should add a preamble to tor-design saying it's out of date.
N . Document transport and natdport
o In man page
- In a good HOWTO.
- Update dir-spec with decisions made on these issues:
o clients don't log as loudly when they receive them
o they don't count toward the 3-strikes rule
D But eventually, we give up after getting a lot of 503s.
D Delay when we get a lot of 503s, rather than punting onto the
servers that have given us 503s?
o Add a 'BadDirectory' flag to statuses.
o authorities should *never* 503 a cache, and should never 503
network status requests.
D They can 503 client descriptor requests when they feel like it.
How can they distinguish? Not implemented for now, maybe
should abandon.
- update dir-spec with what we decided for each of these
Things we'd like to do in 0.2.0.x:
- Proposals:
- 101: Voting on the Tor Directory System
- 104: Long and Short Router Descriptors (by Jun 1)
- 105: Version negotiation for the Tor protocol (finalize by Jun 1)
- Refactoring:
- Make resolves no longer use edge_connection_t unless they are actually
_on_ on a socks connection: have edge_connection_t and (say)
dns_request_t both extend an edge_stream_t, and have p_streams and
n_streams both be linked lists of edge_stream_t.
- Make cells get buffered on circuit, not on the or_conn.
- Don't move them into the target conn until there is space on the
target conn's outbuf.
- Also, only package data from exitconns when there is space on the
target OR conn's outbuf.
- MAYBE kill stalled circuits rather than stalled connections; consider
anonymity implications.
- Move all status info out of routerinfo into local_routerstatus. Make
"who can change what" in local_routerstatus explicit. Make
local_routerstatus (or equivalent) subsume all places to go for "what
router is this?"
- Remove socketpair-based bridges conns, and the word "bridge". (Use
shared (or connected) buffers for communication, rather than sockets.)
- Generate torrc.{complete|sample}.in, tor.1.in, the HTML manual, and the
online config documentation from a single source.
- Have clients do TLS connection rotation less often than "every 10
minutes" in the thrashy case, and more often than "once a week" in the
extra-stable case.
- Streamline how we pick entry nodes: Make choose_random_entry() have
less magic and less control logic.
- Implement TLS shutdown properly when possible.
- Maybe move NT services into their own module.
- Autoconf cleanups and improvements:
o Remove redundant event.h check.
- Check for zlib with the same machinery as for libevent and openssl.
- Make the "no longer strictly accurate" message accurate.
- Tell the user what -dev package to install based on OS.
- Detect correct version of libraries.
o Run autoupdate
- Refactor networkstatus generation:
- Use networkstatus_getinfo_helper_single() as base of
networkstatus generation; eliminate duplicate code.
- Include "v" line in getinfo values.
- Features:
- Traffic priorities (by Jun 1)
- Ability to prioritize own traffic over relayed traffic.
- Implement a DNS proxy
- Add a way to request DNS resolves from the controller.
- A better UI for authority ops.
- Follow weasel's proposal, crossed with mixminion dir config format
- Write a proposal
- Bridges (rudimentary version) (By Jun 1)
- Ability to specify bridges manually
- Use bridges to build circuits
- Ask all directory questions to bridge via BEGIN_DIR.
- Ability to act as dir cache without a dir port.
- Bridges publish to bridge authorities
- Rudimentary "do not publish networkstatus" option for bridge
authorities.
- Clients can ask bridge authorities for more bridges.
- Fix BEGIN_DIR so that you connect to bridge of which you only
know IP (and optionally fingerprint), and then use BEGIN_DIR to learn
more about it.
- Bridges (not necessarily by Jun 1)
- Clients can ask bridge authorities for updates on known bridges.
- More TLS normalization work: make Tor less easily
fingerprinted. (Researched by Jun 1)
- Directory system improvements
- config option to publish what ports you listen on, beyond
ORPort/DirPort. It should support ranges and bit prefixes (?) too.
- Let controller set router flags for authority to transmit, and for
client to use.
- Support relaying streams to ipv6.
- Let servers decide to support BEGIN_DIR but not DirPort.
- Tor should bind its ports before dropping privs, so users don't
have to do the ipchains dance.
- Blocking-resistance.
- It would be potentially helpful to https requests on the OR port by
acting like an HTTPS server.
o Deprecations:
o Remove v0 control protocol.
- Packaging:
- Can we switch to polipo? (Jun 1)
- If we haven't replaced privoxy, lock down its configuration in all
packages, as documented in tor-doc-unix.html
P - make the nsis mingw packaging scripts fail if it tries to parse
a file but the file is missing.
Deferred from 0.1.2.x:
- BEGIN_DIR items
- turn the received socks addr:port into a digest for setting .exit
- handle connect-dir streams that don't have a chosen_exit_name set.
- 'networkstatus arrived' event
- More work on AvoidDiskWrites?
- Get some kind of "meta signing key" to be used solely to sign
releases/to certify releases when signed by the right people/
to certify sign the right people's keys? Also use this to cert the SSL
key, etc. (Proposal 103)
- per-conn write buckets
- separate config options for read vs write limiting
(It's hard to support read > write, since we need better
congestion control to avoid overfull buffers there. So,
defer the whole thing.)
P - Figure out why dll's compiled in mingw don't work right in WinXP.
P - Figure out why openssl 0.9.8d "make test" fails at sha256t test.
- don't do dns hijacking tests if we're reject *:* exit policy?
(deferred until 0.1.1.x is less common)
- Directory guards
- RAM use in directory authorities.
- Memory use improvements:
- Look into pulling serverdescs off buffers as they arrive.
- Save and mmap v1 directories, and networkstatus docs; store them
zipped, not uncompressed.
- Switch cached_router_t to use mmap.
- What to do about reference counts on windows? (On Unix, this is
easy: unlink works fine. (Right?) On Windows, I have doubts. Do we
need to keep multiple files?)
- What do we do about the fact that people can't read zlib-
compressed files manually?
- If the client's clock is too far in the past, it will drop (or
just not try to get) descriptors, so it'll never build circuits.
- Tolerate clock skew on bridge relays.
X Eventdns improvements
X Have a way to query for AAAA and A records simultaneously.
X Improve request API: At the very least, add the ability to construct
a more-or-less arbitrary request and get a response.
X (Can we suppress cnames? Should we?)
- Now that we're avoiding exits when picking non-exit positions,
we need to consider how to pick nodes for internal circuits. If
we avoid exits for all positions, we skew the load balancing. If
we accept exits for all positions, we leak whether it's an internal
circuit at every step. If we accept exits only at the last hop, we
reintroduce Lasse's attacks from the Oakland paper.
- We should ship with a list of stable dir mirrors -- they're not
trusted like the authorities, but they'll provide more robustness
and diversity for bootstrapping clients.
- A way to adjust router flags from the controller.
(How do we prevent the authority from clobbering them soon after?)
- Better estimates in the directory of whether servers have good uptime
(high expected time to failure) or good guard qualities (high
fractional uptime).
- AKA Track uptime as %-of-time-up, as well as time-since-last-down
- Have a "Faster" status flag that means it. Fast2, Fast4, Fast8?
- spec
- implement
- Windows server usability
- Solve the ENOBUFS problem.
- make tor's use of openssl operate on buffers rather than sockets,
so we can make use of libevent's buffer paradigm once it has one.
- make tor's use of libevent tolerate either the socket or the
buffer paradigm; includes unifying the functions in connect.c.
- We need a getrlimit equivalent on Windows so we can reserve some
file descriptors for saving files, etc. Otherwise we'll trigger
asserts when we're out of file descriptors and crash.
M - rewrite how libevent does select() on win32 so it's not so very slow.
- Add overlapped IO
- Add an option (related to AvoidDiskWrites) to disable directory caching.
- Finish status event implementation and accompanying getinfos
- Missing events:
- DIR_REACHABLE
- BAD_DIR_RESPONSE (Unexpected directory response; maybe we're behind
a firewall.)
- BAD_PROXY (Bad http or https proxy)
- UNRECOGNIZED_ROUTER (a nickname we asked for is unavailable)
- Status events related to hibernation
- something about failing to parse our address?
from resolve_my_address() in config.c
- sketchy OS, sketchy threading
- too many onions queued: threading problems or slow CPU?
- Missing fields:
- TIMEOUT on CHECKING_REACHABILITY
- GETINFO status/client, status/server, status/general: There should be
some way to learn which status events are currently "in effect."
We should specify which these are, what format they appear in, and so
on.
Minor items for 0.1.2.x as time permits:
- include bandwidth breakdown by conn->type in BW events.
- Unify autoconf search code for libevent and openssl. Make code
suggest platform-appropriate "devel" / "dev" / whatever packages
if we can link but we can't find the headers.
- Recommend polipo? Please?
- Make documentation realize that location of system configuration file
will depend on location of system defaults, and isn't always /etc/torrc.
- Review torrc.sample to make it more discursive.
- a way to generate the website diagrams from source, so we can
translate them as utf-8 text rather than with gimp.
R - add d64 and fp64 along-side d and fp so people can paste status
entries into a url. since + is a valid base64 char, only allow one
at a time. spec and then do.
- When we export something from foo.c file for testing purposes only,
make a foo_test.h file for test.c to include.
- The Debian package now uses --verify-config when (re)starting,
to distinguish configuration errors from other errors. Perhaps
the RPM and other startup scripts should too?
- add a "default.action" file to the tor/vidalia bundle so we can fix the
https thing in the default configuration:
http://wiki.noreply.org/noreply/TheOnionRouter/TorFAQ#PrivoxyWeirdSSLPort
. Flesh out options_description array in src/or/config.c
X If we try to publish as a nickname that's already claimed, should
we append a number (or increment the number) and try again? This
way people who read their logs can fix it as before, but people
who don't read their logs will still offer Tor servers.
- Fall back to unnamed; warn user; send controller event. ("When we
notice a 'Rejected: There is already a named server with this nickname'
message... or maybe instead when we see in the networkstatuses that
somebody else is Named with the name we want: warn the user, send a
STATUS_SERVER message, and fall back to unnamed.")
- Rate limit exit connections to a given destination -- this helps
us play nice with websites when Tor users want to crawl them; it
also introduces DoS opportunities.
- 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 anonymity implications.
- Display the reasons in 'destroy' and 'truncated' cells under some
circumstances?
- If the server is spewing complaints about raising your ulimit -n,
we should add a note about this to the server descriptor so other
people can notice too.
- cpu fixes:
- see if we should make use of truncate to retry
. 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.
- packaging and ui stuff:
. multiple sample torrc files
. figure out how to make nt service stuff work?
. Document it.
- Vet all pending installer patches
- Win32 installer plus privoxy, sockscap/freecap, etc.
- Vet win32 systray helper code
- Improve controller
- a NEWSTATUS event similar to NEWDESC.
- 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.
- What do we want here, exactly?
- Specify and implement it.
- Change stream status events analogously.
- What do we want here, exactly?
- Specify and implement it.
- Make other events "better".
- Change stream status events analogously.
- What do we want here, exactly?
- Specify and implement it.
- Make other events "better" analogously
- What do we want here, exactly?
- 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.
- Make everything work with hidden services
Future version:
- when we hit a funny error from a dir request (eg 403 forbidden),
but tor is working and happy otherwise, and we haven't seen many
such errors recently, then don't warn about it.
- More consistent error checking in router_parse_entry_from_string().
I can say "banana" as my bandwidthcapacity, and it won't even squeak.
- Include the output of svn info/svk info output into the binary, so
it's trivial to see what version a binary was built from.
- Add a doxygen style checker to make check-spaces so nick doesn't drift
too far from arma's undocumented styleguide. Also, document that
styleguide in HACKING. (See r9634 for example.)
- exactly one space at beginning and at end of comments, except i
guess when there's line-length pressure.
- if we refer to a function name, put a () after it.
- only write <b>foo</b> when foo is an argument to this function.
- doxygen comments must always end in some form of punctuation.
- capitalize the first sentence in the doxygen comment, except
when you shouldn't.
- avoid spelling errors and incorrect comments. ;)
- Should TrackHostExits expire TrackHostExitsExpire seconds after their
*last* use, not their *first* use?
X Configuration format really wants sections.
- Good RBL substitute.
- Authorities should try using exits for http to connect to some URLS
(specified in a configuration file, so as not to make the List Of Things
Not To Censor completely obvious) and ask them for results. Exits that
don't give good answers should have the BadExit flag set.
- Our current approach to block attempts to use Tor as a single-hop proxy
is pretty lame; we should get a better one.
. 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.
- auth mechanisms to let hidden service midpoint and responder filter
connection requests.
- 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.
- Make router_is_general_exit() a bit smarter once we're sure what it's for.
- 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?
- 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").
- 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?
o tor-resolve script should use socks5 to get better error messages.
- hidserv offerers shouldn't need to define a SocksPort
* figure out what breaks for this, and do it.
- tor should be able to have a pool of outgoing IP addresses
that it is able to rotate through. (maybe)
- Specify; implement.
- let each hidden service (or other thing) specify its own
OutboundBindAddress?
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)
Non-Coding:
- Mark up spec; note unclear points about servers
- Mention controller libs someplace.
. more pictures from ren. he wants to describe the tor handshake
NR- write a spec appendix for 'being nice with tor'
- tor-in-the-media page
- Remove need for HACKING file.
- Figure out licenses for website material.
- Specify the keys and key rotation schedules and stuff
Website:
- 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.
R - make a page with the hidden service diagrams.
- ask Jan to be the translation coordinator? add to volunteer page.
- add a page for localizing all tor's components.
- It would be neat if we had a single place that described _all_ the
tor-related tools you can use, and what they give you, and how well they
work. Right now, we don't give a lot of guidance wrt
torbutton/foxproxy/privoxy/polipo in any consistent place.