Filename: 001-process.txt
Title: The Tor Proposal Process
Author: Nick Mathewson
Created: 30-Jan-2007
Status: Meta
Overview:
This document describes how to change the Tor specifications, how Tor
proposals work, and the relationship between Tor proposals and the
specifications.
This is an informational document.
Motivation:
Previously, our process for updating the Tor specifications was maximally
informal: we'd patch the specification (sometimes forking first, and
sometimes not), then discuss the patches, reach consensus, and implement
the changes.
This had a few problems.
First, even at its most efficient, the old process would often have the
spec out of sync with the code. The worst cases were those where
implementation was deferred: the spec and code could stay out of sync for
versions at a time.
Second, it was hard to participate in discussion, since you had to know
which portions of the spec were a proposal, and which were already
implemented.
Third, it littered the specifications with too many inline comments.
[This was a real problem -NM]
[Especially when it went to multiple levels! -NM]
[XXXX especially when they weren't signed and talked about that
thing that you can't remember after a year]
How to change the specs now:
First, somebody writes a proposal document. It should describe the change
that should be made in detail, and give some idea of how to implement it.
Once it's fleshed out enough, it becomes a proposal.
Like an RFC, every proposal gets a number. Unlike RFCs, proposals can
change over time and keep the same number, until they are finally
accepted or rejected. The history for each proposal
will be stored in the Tor repository.
Once a proposal is in the repository, we should discuss and improve it
until we've reached consensus that it's a good idea, and that it's
detailed enough to implement. When this happens, we implement the
proposal and incorporate it into the specifications. Thus, the specs
remain the canonical documentation for the Tor protocol: no proposal is
ever the canonical documentation for an implemented feature.
(This process is pretty similar to the Python Enhancement Process, with
the major exception that Tor proposals get re-integrated into the specs
after implementation, whereas PEPs _become_ the new spec.)
{It's still okay to make small changes directly to the spec if the code
can be
written more or less immediately, or cosmetic changes if no code change is
required. This document reflects the current developers' _intent_, not
a permanent promise to always use this process in the future: we reserve
the right to get really excited and run off and implement something in a
caffeine-or-m&m-fueled all-night hacking session.}
How new proposals get added:
Once an idea has been proposed on the development list, a properly formatted
(see below) draft exists, and rough consensus within the active development
community exists that this idea warrants consideration, the proposal editors
will officially add the proposal.
To get your proposal in, send it to the tor-dev@lists.torproject.org mailing
list.
What should go in a proposal:
Every proposal should have a header containing these fields:
Filename, Title, Author, Created, Status.
These fields are optional but recommended:
Target, Implemented-In, Ticket**.
The Target field should describe which version the proposal is hoped to be
implemented in (if it's Open or Accepted). The Implemented-In field
should describe which version the proposal was implemented in (if it's
Finished or Closed). The Ticket field should be a ticket number referring
to Tor's canonical bug tracker (e.g. "#7144" refers to
https://bugs.torproject.org/7144) or to a publicly accessible URI where one
may subscribe to updates and/or retrieve information on implementation
status.
** Proposals with assigned numbers of prop#283 and higher are REQUIRED to
have a Ticket field if the Status is OPEN, ACCEPTED, CLOSED, or FINISHED.
The body of the proposal should start with an Overview section explaining
what the proposal's about, what it does, and about what state it's in.
After the Overview, the proposal becomes more free-form. Depending on its
length and complexity, the proposal can break into sections as
appropriate, or follow a short discursive format. Every proposal should
contain at least the following information before it is "ACCEPTED",
though the information does not need to be in sections with these names.
Motivation: What problem is the proposal trying to solve? Why does
this problem matter? If several approaches are possible, why take this
one?
Design: A high-level view of what the new or modified features are, how
the new or modified features work, how they interoperate with each
other, and how they interact with the rest of Tor. This is the main
body of the proposal. Some proposals will start out with only a
Motivation and a Design, and wait for a specification until the
Design seems approximately right.
Security implications: What effects the proposed changes might have on
anonymity, how well understood these effects are, and so on.
Specification: A detailed description of what needs to be added to the
Tor specifications in order to implement the proposal. This should
be in about as much detail as the specifications will eventually
contain: it should be possible for independent programmers to write
mutually compatible implementations of the proposal based on its
specifications.
Compatibility: Will versions of Tor that follow the proposal be
compatible with versions that do not? If so, how will compatibility
be achieved? Generally, we try to not drop compatibility if at
all possible; we haven't made a "flag day" change since May 2004,
and we don't want to do another one.
Implementation: If the proposal will be tricky to implement in Tor's
current architecture, the document can contain some discussion of how
to go about making it work. Actual patches should go on public git
branches, or be uploaded to trac.
Performance and scalability notes: If the feature will have an effect
on performance (in RAM, CPU, bandwidth) or scalability, there should
be some analysis on how significant this effect will be, so that we
can avoid really expensive performance regressions, and so we can
avoid wasting time on insignificant gains.
How to format proposals:
Proposals may be written in plain text (like this one), or in Markdown.
If using Markdown, the header must be wrapped in triple-backtick ("```")
lines. Whenever possible, we prefer the Commonmark dialect of Markdown.
Proposal status:
Open: A proposal under discussion.
Accepted: The proposal is complete, and we intend to implement it.
After this point, substantive changes to the proposal should be
avoided, and regarded as a sign of the process having failed
somewhere.
Finished: The proposal has been accepted and implemented. After this
point, the proposal should not be changed.
Closed: The proposal has been accepted, implemented, and merged into the
main specification documents. The proposal should not be changed after
this point.
Rejected: We're not going to implement the feature as described here,
though we might do some other version. See comments in the document
for details. The proposal should not be changed after this point;
to bring up some other version of the idea, write a new proposal.
Draft: This isn't a complete proposal yet; there are definite missing
pieces. (Despite the existence of this status, the proposal editors
may decline to accept incomplete proposals: please consider asking for
help if you aren't sure how to solve an open issue.) Proposals that
remain in the Draft status for too long are likely to be marked as Dead
or Obsolete.
Needs-Revision: The idea for the proposal is a good one, but the proposal
as it stands has serious problems that keep it from being accepted.
See comments in the document for details.
Dead: The proposal hasn't been touched in a long time, and it doesn't look
like anybody is going to complete it soon. It can become "Open" again
if it gets a new proponent.
Needs-Research: There are research problems that need to be solved before
it's clear whether the proposal is a good idea.
Meta: This is not a proposal, but a document about proposals.
Reserve: This proposal is not something we're currently planning to
implement, but we might want to resurrect it some day if we decide to
do something like what it proposes.
Informational: This proposal is the last word on what it's doing.
It isn't going to turn into a spec unless somebody copy-and-pastes
it into a new spec for a new subsystem.
Obsolete: This proposal was flawed and has been superseded by another
proposal. See comments in the document for details.
The editors maintain the correct status of proposals, based on rough
consensus and their own discretion.
Proposal numbering:
Numbers 000-099 are reserved for special and meta-proposals. 100 and up
are used for actual proposals. Numbers aren't recycled.