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commit 0fc6d07d88f0af8d87b12df4cd9890eabc5e6547 Author: Nick Mathewson nickm@torproject.org AuthorDate: Fri Feb 3 13:01:24 2023 -0500
More verbage in prop340 about the stream_id transition.
Specifically:
* Mention this change in the introduction. * Add a section explaining how to change tor-spec and related proposals. --- proposals/340-packed-and-fragmented.md | 48 ++++++++++++++++++++++++++++++---- 1 file changed, 43 insertions(+), 5 deletions(-)
diff --git a/proposals/340-packed-and-fragmented.md b/proposals/340-packed-and-fragmented.md index 0d83f67..6fb1ca5 100644 --- a/proposals/340-packed-and-fragmented.md +++ b/proposals/340-packed-and-fragmented.md @@ -33,6 +33,9 @@ This proposal combines ideas from [ntor v3](./332-ntor-v3-with-extra-data.md) and prepares for [next-generation relay cryptography](./308-counter-galois-onion).
+Additionally, this proposal has been revised to incorporate another +protocol change, and remove StreamId from the relay cell header. + ## A preliminary change: Relay encryption, version 1.5
We are fairly sure that, whatever we do for our next batch of relay @@ -71,10 +74,9 @@ Relay _messages_ now follow the following format:
We require that "command" is never 0.
-One big change from the current tor protocol is the missing `stream_id` which -we propose to move into the body because most commands set it to 0 because -they don't need it. Meaning that the `stream_id` becomes a value specified -per-command. +One big change from the current tor protocol is something that is _not_ +here: we have moved `stream_id` into the body of the relay message of +those commands that need it.
Messages can be split across relay cells; multiple messages can occur in a single relay cell. We enforce the following rules: @@ -96,7 +98,7 @@ Receivers MUST validate that headers are well-formed and have valid lengths while handling the cell in which the header is encoded. If the header is invalid, the receiver must destroy the circuit.
-### Some examples +
## Negotiation @@ -113,6 +115,42 @@ The `version` field is the `Relay` subprotocol version that the client wants to use. The relay must send back the same extension in its ntor3 handshake to acknowledge support.
+ +## Specifying the message format with moved stream ID. + +Here, we'll specify how to adjust tor-spec to describe the `stream_id` +move correctly. + +Below, suppose that `Relay=V` denotes whatever version of the relay +message subprotocol denotes support for this proposal. + +For all relay message types that include a stream ID, we insert +the following at the beginning of their fields: + +>``` +> STREAM_ID [2 bytes] (Present when Relay protocol version >= V). +>``` + +We add a note saying: + +> STREAM_ID is part of many message types, when using Relay protocol +> version V or later. Earlier versions of the Relay protocol put +> STREAM_ID in the RELAY header. In those versions, the field is +> STREAM_ID omitted from the message. +> +> Except when noted, STREAM_ID may not be zero. + +The following message types take required stream IDs: `BEGIN`, `DATA`, `END`, +`CONNECTED`, `RESOLVE`, `RESOLVED`, and `BEGIN_DIR`, `XON`, `XOFF`. + +The following message type takes an *optional* stream ID: `SENDME`. +(*Stream-level sendmes are not a thing anymore with proposal 324, but I +want to give implementations the freedom to implement prop324 and this +proposal in either order.*) + +The following message types from proposal 339 (UDP) take required stream +IDs: `CONNECT_UDP`, `CONNECTED_UDP` and `DATAGRAM`. + ## Migration
We add a consensus parameter, "streamed-relay-messages", with default