GitLab

There's some inconsistency among the specs (and code doesn't necessarily match the specs either) about how pluggable transports quote or escape special characters in transport arguments. See #12930 (moved) for additional background.

Proposal:

• Explicitly disallow whitespace (or control characters for that matter) in keys or values of PT arguments. (No PT does this now that I know of, and people with Unix-ish backgrounds are likely to avoid using whitespace in this context anyway.)
• Explicitly disallow = and \ in keys of PT arguments. (I'm assuming PT designers have more flexibility in choosing keys than value encodings, but if this poses a problem for someone please speak up.)
• Allow but discourage = in values of PT arguments. (If you encode something in base64 or base32, try to truncate the trailing padding.)
• Allow but discourage \ in values of PT arguments.
• Require \ to be escaped by \ (in addition to escaping ,, which is already required) in SMETHOD ARGS and transport lines of extra-info documents. (Almost everywhere else I've seen that uses \ for escaping also requires that \ itself be escaped, and it's closer to what people already expect. goptlib already implemented this despite it not being specified in pt-spec.txt)
• Do not require = to be escaped by \ in SMETHOD ARGS and transport lines of extra-info documents.
• Do not require any PT argument characters to be escaped in BridgeDB output or Bridge lines in torrc. (Any \ characters stand for themselves. This requires the fewest changes to existing tor code.)