webrtc/: Remove browser-to-browser use-case

This will be specified in a second iteration of this specification.

webrtc/README.md

@@ -16,8 +16,6 @@ Interest Group: [@marten-seemann]
     - [Addressing](#addressing)
     - [Connection Establishment](#connection-establishment)
         - [Browser to public Server](#browser-to-public-server)
-        - [Browser to Browser](#browser-to-browser)
-            - [Open Questions](#open-questions)
     - [Multiplexing](#multiplexing)
         - [Ordering](#ordering)
         - [Head-of-line blocking](#head-of-line-blocking)
@@ -38,9 +36,6 @@ Interest Group: [@marten-seemann]
    certificate. Nor can we establish a plain TCP or QUIC connection from within
    a browser.
 
-2. **Hole punching in the browser**: Enable two browsers or a browser and a
-   server node to connect even though one or both are behind a NAT / firewall.
-
 ## Addressing
 
 WebRTC multiaddresses are composed of an IP and UDP address component, followed
@@ -141,66 +136,6 @@ reachable but _B_ does not have a TLS certificate trusted by _A_.
 WebRTC can run both on UDP and TCP. libp2p WebRTC implementations MUST support
 UDP and MAY support TCP.
 
-### Browser to Browser
-
-Scenario: Browser _A_ wants to connect to Browser node _B_ with the help of
-server node _R_.
-
-_Note that this section is a draft only for now, will be removed before merging
-the first iteration of the specification (browser-to-server) and reintroduced in
-the second iteration i.e. sufficiently specifying browser-to-server._
-
-1. _B_ runs inside a browser and can thus not listen for incoming connections.
-   _B_ connects to a public server node _R_ and uses the Circuit Relay v2
-   protocol to make a reservation.
-
-2. _B_ advertises its relayed address through some external mechanism.
-
-3. _A_ discovers _B_'s relayed address. _A_ connects to _R_ and establishes a
-   relayed connection to _B_ via the Circtui Relay v2 protocol.
-
-4. _A_ and _B_ both create a `RTCPeerConnection` and generate an _offer_ and an
-   _answer_ respectively. See `icegatheringstatechange` below on how these may
-   already contain the addresses of the loca node.
-
-5. _A_ and _B_ exchange the generated _offer_ and _answer_ through some protocol
-   (e.g. an altered DCUtR) via the relayed connection.
-
-6. _A_ and _B_ set the exchanged _offer_ and _answer_ and thus initiate the
-   connection establishment.
-
-7. Messages on the established `RTCDataChannel` are framed using the message
-   framing mechanism described in [Multiplexing](#multiplexing).
-
-8. The remote is authenticated via an additional Noise handshake. See
-   [Connection Security](#connection-security).
-
-The above browser-to-browser WebRTC connection establishment replaces the
-existing [libp2p WebRTC star](https://github.com/libp2p/js-libp2p-webrtc-star)
-and [libp2p WebRTC direct](https://github.com/libp2p/js-libp2p-webrtc-direct)
-protocols.
-
-#### Open Questions
-
-- Can _Browser_ control the lifecycle of its local TLS certificate, i.e. can
-  _Browser_ use the same TLS certificate for multiple WebRTC connections?
-
-  Yes. For the lifetime of the page, one can generate a certificate once and
-  reuse it across connections. See also
-  https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/RTCPeerConnection#using_certificates
-
-- Can two _Browsers_ exchange their SDP packets via a third server node using
-  Circuit Relay v2 and DCUtR? Instead of exchanging the original SDP packets,
-  could they exchange their multiaddr and construct the remote's SDP packet
-  based on it?
-
-- Instead of using trickle ICE, we could as well wait for the candidate
-  gathering. See
-  https://github.com/pion/webrtc/blob/c1467e4871c78ee3f463b50d858d13dc6f2874a4/examples/insertable-streams/main.go#L141-L142
-  as one example. In the browser, one can wait for the
-  [`icegatheringstatechange`
-  event](https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/icegatheringstatechange_event).
-
 ## Multiplexing
 
 The WebRTC browser APIs do not support half-closing of streams nor resets of the