Hi Philipp,

On 13 Jun 2019, at 09:41, Philipp Winter phw@nymity.ch wrote:

We are working on improving Tor's pluggable transports specification: https://spec.torproject.org/pt-spec

The goal is to make the spec useful to more people and fix issues that have accumulated over the years. For more context, have a look at the following ticket, which we use to coordinate this effort: https://bugs.torproject.org/29285

Before changing the spec, we need to understand its shortcomings and what issues implementers have run into. For those of you who have experience with the spec -- either Tor's version 1.0 or version 2.1 maintained by pluggabletransports.info -- please let us know:

• What version of the PT specification and what library implementation

(if any) are you using?

Yawning, David, and I pointed out a bunch of issues in PT 2.0 and 2.1:

https://lists.torproject.org/pipermail/tor-dev/2017-June/012332.html

Most of these issues were present in PT 1.0, some of them were newly introduced in 2.0.

Some of the issues were caused by tor's limited PT interface, which we've improved recently.

Some were also caused by confusion over whether the application or the transport should take responsibility for certain features.

I've also opened some trac tickets over the past few years. I assume they've been triaged, and someone has an overview of which changes we have wanted to make in the past.

• What has your experience been with the PT specification?

I am very confused by all the different specifications and implementations.

• How would you improve the specification?

Start by defining a scope for pluggable transports. Ruthlessly limit the specification to a programming language-agnostic interface. Allow for extensions to the core specification, which can be included once they are in active use.

Document language-specific APIs separately. Or create a language-agnostic API using some kind of binding generator. (If that results in a functional and usable interface.)

T