Filename: ExtraRelayDescriptorFields.txt

Title: Adding new X- fields to relay descriptor

Author: Virgil Griffith, Nick Mathewson

Created: 2014-06-03

Status: Open

1. Motivation

We wish to allow developers to build new applications atop relays. Towards this

end, we wish to add the ability for users to specify arbitrary new key-value

entries under the "X-" namespace.

2. Proposal

Allow optional key-value lines in the relay's torrc file.  These lines will be

mirrored in the relay's descriptor which is then published in the directory

consensus.

For example:

X-bitcoin 19mP9FKrXqL46Si58pHdhGKow88SUPy1V8

X-gravatar https://s.gravatar.com/avatar/d27fce46c9ac41a41bb52455ae75701d

X-favoritequote Be excellent to each other.  Party on dudes!

X-foo bar

The value field must be printable ASCII (characters 32-126).  The value must

not under any condition contain a newline.  The key may contain lowercase

ASCII letters (a-z), digits, underscore, or dash.  In regex, [-_0-9a-z].

There may need to be a maximum sum length of the X- entries.  This is

left to the developers.  I propose a maximum sum length of 5 kilobytes.

To mitigate the chance of a malformed torrc file, I additionally propose there

be a schema for the relay descriptor, and if the relay descriptor fails to

match the schema it errors to the user to change her torrc file.

-V