jiebi/CodeConvo huggingface dataset:
Code change:
can be mounted using spoofed source addresses.  In determining this limit, servers only count the size of successfully processed packets. <del> Clients MUST pad UDP datagrams that contain only Initial packets to at least 1200 bytes.  Once a client has received an acknowledgment </del> <ins> Clients MUST ensure that UDP datagrams containing Initial packets are sized to at least 1200 bytes, adding padding to packets in the datagram as necessary.  Once a client has received an acknowledgment </ins> for a Handshake packet it MAY send smaller datagrams.  Sending padded datagrams ensures that the server is not overly constrained by the amplification restriction.

Related discussion:
text: This change does two things: Clarify that if UDP datagram contains Initial packets, it must be at least 1200 bytes in size; and Rule out padding the UDP datagram with junk (the "padding packets" part) as NAME suggested earlier. Issue is only about (1). Not that I am against (2), but this is just so that we are clear.
I think that the reinterpretation of the text here has introduced the second problem NAME mentions. This also has the unfortunate consequence of disallowing small acknowledgment datagrams (for HelloRetryRequest in particular). This might need to be more carefully phrased.
As NAME said, this is an editorial change, so I'm going to merge. The substantive one is in NAME
NAME -- you're right, but I think this was unintentional earlier. I think if we want to make a case for allowing junk, that should be discussed separately. The proposed text captures what I believe our intent was.
states: This seemingly says that the first UDP datagram that has two coalesced packets, Initial and 0-RTT, can be smaller than 1200 bytes. I don't believe that's the intention.
Agreed, I believe the "only" needs to removed unless I'm missing some other intent.
I don't think that is sufficient. The intent of this was to allow the client to send Initial packets that acknowledge server Initial packets without padding to 1200.
Given PADDING is supposed to count towards bytes in flight, but it's not ack-eliciting, a special case for ACK-only packets makes sense. I'd be inclined to specify ACK-only packets as the exception, opposed to basing it on receiving an ACK of Handshake packets or some other mechanism.
As stated in URL, I prefer to stop requiring the use of full-sized packets once the client observes a response from server. Reasons: QUIC stacks would have the logic to change rules based on if the peer's address has been validated due to the 3-packet rule on the server side. It's just about using the same logic for padding on the client side. Implementations that prefer to pad all the Initial packets it sends can do so anyways. Regardless of what we decide, the server side logic would be indifferent; i.e. create new connection context only when observing a full-sized Initial packet.
Code change:
can be mounted using spoofed source addresses.  In determining this limit, servers only count the size of successfully processed packets. <del> Clients MUST pad UDP datagrams that contain only Initial packets to at least 1200 bytes.  Once a client has received an acknowledgment </del> <ins> Clients MUST ensure that UDP datagrams containing Initial packets are sized to at least 1200 bytes, adding padding to packets in the datagram as necessary.  Once a client has received an acknowledgment </ins> for a Handshake packet it MAY send smaller datagrams.  Sending padded datagrams ensures that the server is not overly constrained by the amplification restriction.

Related discussion:
text: tl;dr: we should always pad to 1200 for UDP datagrams that contain Initial packets. The reason we pad to 1200 is to provide a server with plenty of inbound bytes so that it can send outbound bytes prior to path validation. Padding to 1200 has sub-optimal performance in certain cases. In particular, it makes datagrams containing a simple ACK enormous. So the original thought was to try to find a case where we could allow for smaller datagrams to be sent. I think that in both alternative designs we have a problem with the interaction with our DoS defense. And while those problems might only exist in the abstract for now, I think that the best answer is to pad to 1200 always. (I will suggest rewording the text separately.) An ACK-only Initial packet is sent at the tail of the Initial phase. That is the obvious candidate for consideration here. But there are other cases where small Initial packets might be sent. The looser requirement NAME suggests is less than ideal for HelloRetryRequest. A client can receive a HelloRetryRequest and be forced to send another ClientHello. We can't assume here that the server is using the HelloRetryRequest to validate the client address (though it certainly can). If the ClientHello message is small, the number of bytes that a server can send is still limited. If the client doesn't pad, the server can still count the original ClientHello toward its budget, but it doesn't get significant additional budget from the client. And that budget doesn't increase when packets are lost. So it could be that the server is stuck with 3x whatever it gets in ACKs, which is not a lot. It's worse if you consider the possibility of the ServerHello being enormous (hello PQ crypto). At this point, the server won't have validated the client address and so is still limited in what it can send. Ideally, we want the packets to be big so that the server gets more budget for sending and isn't limited to sending tiny packets. But if all the client sends is small ACK-only packets (under either proposed amendment, either what NAME or NAME describe), the increased allowance is very small. Based on this, I would suggest that we reluctantly say that all Initial-carrying datagrams need to be 1200 bytes or more.
Code change:
can be mounted using spoofed source addresses.  In determining this limit, servers only count the size of successfully processed packets. <del> Clients MUST pad UDP datagrams that contain only Initial packets to at least 1200 bytes.  Once a client has received an acknowledgment </del> <ins> Clients MUST ensure that UDP datagrams containing Initial packets are sized to at least 1200 bytes, adding padding to packets in the datagram as necessary.  Once a client has received an acknowledgment </ins> for a Handshake packet it MAY send smaller datagrams.  Sending padded datagrams ensures that the server is not overly constrained by the amplification restriction.

Related discussion:
text: For the case of the ACK at the tail, most of the designs proposed for key discard will result in that packet not being sent. If it is sent, there are plenty of cases where it will be a packet with Initial (ACK), Handshake (ACK + ...Finished) and 1-RTT data, so the requirement is met without wasting bytes at all. But for ACK of big ServerHello messages or HelloRetryRequest, the overhead is regrettably necessary.
SGTM. I agree this greatly incentivizes good coalescing, but otherwise I don't see any downsides. And simple is good. Even when suggesting the special case for ACK-only packets, it felt like a premature optimization.
Works for me. It's a corner case anyways. Unless HRR is involved, client will not send an Initial in response to the server's Initial, assuming we decide to continue dropping the Initial keys when the client receives a handshake packet.
A potential friendly amendment, but then we should proceed. I would say after confirming with chairs, because there was a pretty strong design decision involved here, but technically this is only an editorial change.
Code change:
the sender will not have the keys necessary to construct an MLSCiphertext object. <del> 13.1.9.1. </del> <ins> 13.1.8.1. </ins> The "external_senders" extension is a group context extension that contains credentials of senders that are permitted to send external

Related discussion:
text: The way the spec is written now, clients need to implement all proposal types, and they must react to appropriately to all valid proposals, including AppAck. AppAck in a large, busy group could result in a situation where clients with longer latency connections to the DS (perhaps in a different country, using satellite, or using some wireless networks) might be effectively prevented from sending any messages, or worse could be prevented from sending AppAcks because their proposals are always a few hundred milliseconds late. I think AppAcks still have a place is relatively small groups with low message volumes, but I have a few suggestions: 1) Describe this issue either in the AppAck proposal section or in the security considerations section 2) I think it is reasonable for a group to consider some proposal types invalid. If there is consensus with this position, I'd like to make this clear with an extra sentence or two. If that is not the consensus, then I will propose that only Add, Remove, and Update are assumed to be supported by each group, and other proposal types have to be explicitly added.
My team had similar comments. I agree that this shouldn't be a 100% necessary thing to support.
I would differentiate between "support" in the sense of "if you receive one, do something sensible with it" vs. "send this under some circumstances". My understanding was that the requirement here was the former, and even that the definition of "sensible" was up to the implementation. The thinking being that if an application wanted to get some anti-suppression properties, it could send and verify these on some schedule, but when exactly they would be sent would be up to the application. Does that alleviate some of the concern here? If so, I would totally be open to clarifying that. To NAME point about latency, it seems like we could add an parameter to AppAck so that you could report on past epochs' messages in a future epoch. On considering proposal types invalid -- I think there has always been a notion that applications might have policies on which proposals are acceptable. Not just at the proposal type level, but at even finer granularities. Think about things like groups where only certain members are allowed to add/remove participants. I would also be fine laying this out more explicitly, though maybe it would be a more natural fit in the architecture document.
Code change:
the sender will not have the keys necessary to construct an MLSCiphertext object. <del> 13.1.9.1. </del> <ins> 13.1.8.1. </ins> The "external_senders" extension is a group context extension that contains credentials of senders that are permitted to send external

Related discussion:
text: Sorry, meant to delete a comment, closed the issue instead.
In the past I've expressed reservations about AppAck being included in the spec. I don't think it's sufficiently general (it only handles a one specific pattern of message loss and won't work for others, per NAME comment), and I don't like that we don't specify how to handle dropped messages in any way. The AppAck functionality is likely to just be re-invented at the application-level because of this. For example, AppAck can't be used to implement read receipts It doesn't help detect the suppression of handshake messages It doesn't handle cases where some messages must be delivered and others may be dropped So instead I would propose removing AppAck from the spec.
I've opened a PR to that effect in .
Virtual interim 2022-05-19 Agreement that the bar for support is quite low ... but you don't get a security property unless members actually do something more than the minimum That sort of implies that you want the group to opt in to this mechanism So we should have a new proposal type in a separate I-D
(To be clear, AppAck should move from the main spec here to its own I-D.)
One comment that renumbering the groupcontextextensions proposal was probably a bad idea from a process perspective which we should avoid doing in the future. In this case it seems unlikely that many people have implemented it who could not make a breaking change.
Code change:
This document uses the Augmented BNF defined in RFC5234 and updated by RFC7405. <del> 1.2. The OpenAPI Specification Media Types convey OpenAPI Specification (OAS) files as defined in oas for version 3.0.0 and above. Those files can be serialized in JSON or yaml.  Since there are multiple OpenAPI Specification Specifications versions, those media- types support the "version" parameter. The following examples conveys the desire of a client to receive an OpenAPI Specification resource preferably in the following order: openapi 3.1 in yaml openapi 3.0 in yaml any openapi version in json </del> 2. <del> Security requirements for both media type and media type suffix registrations are discussed in Section 4.6 of MEDIATYPE. </del> <ins> This section describes the information required to register the above media types. </ins> <del> 3. </del> <ins> 2.1. </ins> <del> This specification defines the following new Internet media types MEDIATYPE. 3.1. </del> <ins> The following information serves as the registration form for the "application/yaml" media type. </ins> Type name: application

Related discussion:
text: introduce numbered sections for YAML NAME since each media type is defined in its IANA consideration, would it be ok for you if we just add a section for YAML? Feel free to PR with another proposal.
NAME could you PTAL ? :)
to be honest, i prefer definitions to have URIs and not just registrations. but if we have URIs, that's already a lot better than not having URIs! thanks!
it's maybe just OCD (and because it's very useful for URL to have linkable references) but i think it's nice to have numbered sections for everything that's being defined in the spec. in this case, i suggest to have a numbered section for each of the four media types, and to have a brief explanation of what it identifies. that way, each definition is self-contained and can be easily referenced when necessary. NAME NAME
Code change:
If Host A does not receive a TCP RST in reply to its MP_FASTCLOSE after one retransmission timeout (RTO) (the RTO of the subflow <del> where the MPTCP_RST has been sent), it SHOULD retransmit the </del> <ins> where the MP_FASTCLOSE has been sent), it SHOULD retransmit the </ins> MP_FASTCLOSE.  The number of retransmissions SHOULD be limited to avoid this connection from being retained for a long time, but this limit is implementation specific.  A RECOMMENDED number is 3. If no TCP RST is received in response, Host A SHOULD send a TCP <del> RST itself when it releases state in order to clear any remaining state at middleboxes. </del> <ins> RST with the MP_FASTCLOSE option itself when it releases state in order to clear any remaining state at middleboxes. Upon receipt of a RST with MP_FASTCLOSE, containing the valid key, Host B tears down all subflows.  Host B can now close the whole MPTCP connection (it transitions directly to CLOSED state). </ins> 3.6.

Related discussion:
text: Adding Olivier's proposed text about the Fast-Close (cfr., URL) and integrated a shorter version of URL Hello, Sorry for being late with this, but the beginning of the fall semester is always too busy for me. During the summer, there was a discussion on the FASTCLOSE option that was triggered by Francois. The current text of RFC6824bis uses the FASTCLOSE option inside ACK packets, but deployment experience has shown that this results in additional complexity since the ACK must be retransmitted to ensure its reliable delivery. Here is a proposed update for section 3.5 that allows a sender to either send FASTCLOSE inside ACK or RST while a receiver must be ready to process both. Changes are marked with Fast Close Regular TCP has the means of sending a reset (RST) signal to abruptly close a connection. With MPTCP, a reguler RST only has the scope of the subflow and will only close the concerned subflow but not affect the remaining subflows. MPTCP's connection will stay alive at the data level, in order to permit break-before-make handover between subflows. It is therefore necessary to provide an MPTCP-level "reset" to allow the abrupt closure of the whole MPTCP connection, and this is the MPFASTCLOSE option. MPFASTCLOSE is used to indicate to the peer that the connection will be abruptly closed and no data will be accepted anymore. The reasons for triggering an MPFASTCLOSE are implementation specific. Regular TCP does not allow sending a RST while the connection is in a synchronized state [RFC0793]. Nevertheless, implementations allow the sending of a RST in this state, if, for example, the operating system is running out of resources. In these cases, MPTCP should send the MPFASTCLOSE. This option is illustrated in Figure 14.
Code change:
If Host A does not receive a TCP RST in reply to its MP_FASTCLOSE after one retransmission timeout (RTO) (the RTO of the subflow <del> where the MPTCP_RST has been sent), it SHOULD retransmit the </del> <ins> where the MP_FASTCLOSE has been sent), it SHOULD retransmit the </ins> MP_FASTCLOSE.  The number of retransmissions SHOULD be limited to avoid this connection from being retained for a long time, but this limit is implementation specific.  A RECOMMENDED number is 3. If no TCP RST is received in response, Host A SHOULD send a TCP <del> RST itself when it releases state in order to clear any remaining state at middleboxes. </del> <ins> RST with the MP_FASTCLOSE option itself when it releases state in order to clear any remaining state at middleboxes. Upon receipt of a RST with MP_FASTCLOSE, containing the valid key, Host B tears down all subflows.  Host B can now close the whole MPTCP connection (it transitions directly to CLOSED state). </ins> 3.6.

Related discussion:
text: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+---------------+-------+-----------------------+ +---------------+---------------+-------+-----------------------+ +---------------------------------------------------------------+ Figure 14: Fast Close (MPFASTCLOSE) Option If Host A wants to force the closure of an MPTCP connection, it has two different options : Option A (ACK) : Host A sends an ACK containing the MPFASTCLOSE option on one subflow, containing the key of Host B as declared in the initial connection handshake. On all the other subflows, Host A sends a regular TCP RST to close these subflows, and tears them down. Host A now enters FASTCLOSEWAIT state. Option R (RST) : Host A sends a RST containing the MPFASTCLOSE option on all subflows, containing the key of Host B as declared in the initial connection handshake. Host A can tear the subflows and the connection down immediately. If a host receives a packet with a valid MPFASTCLOSE option, it shall process it as follows : o Upon receipt of an ACK with MPFASTCLOSE, containing the valid key, Host B answers on the same subflow with a TCP RST and tears down all subflows. Host B can now close the whole MPTCP connection (it transitions directly to CLOSED state). o As soon as Host A has received the TCP RST on the remaining subflow, it can close this subflow and tear down the whole connection (transition from FASTCLOSEWAIT to CLOSED states). If Host A receives an MPFASTCLOSE instead of a TCP RST, both hosts attempted fast closure simultaneously. Host A should reply with a TCP RST and tear down the connection. o If Host A does not receive a TCP RST in reply to its MPFASTCLOSE after one retransmission timeout (RTO) (the RTO of the subflow where the MPTCPRST has been sent), it SHOULD retransmit the MPFASTCLOSE.
Code change:
If Host A does not receive a TCP RST in reply to its MP_FASTCLOSE after one retransmission timeout (RTO) (the RTO of the subflow <del> where the MPTCP_RST has been sent), it SHOULD retransmit the </del> <ins> where the MP_FASTCLOSE has been sent), it SHOULD retransmit the </ins> MP_FASTCLOSE.  The number of retransmissions SHOULD be limited to avoid this connection from being retained for a long time, but this limit is implementation specific.  A RECOMMENDED number is 3. If no TCP RST is received in response, Host A SHOULD send a TCP <del> RST itself when it releases state in order to clear any remaining state at middleboxes. </del> <ins> RST with the MP_FASTCLOSE option itself when it releases state in order to clear any remaining state at middleboxes. Upon receipt of a RST with MP_FASTCLOSE, containing the valid key, Host B tears down all subflows.  Host B can now close the whole MPTCP connection (it transitions directly to CLOSED state). </ins> 3.6.

Related discussion:
text: The number of retransmissions SHOULD be limited to avoid this connection from being retained for a long time, but this limit is implementation specific. A RECOMMENDED number is 3. If no TCP RST is received in response, Host A SHOULD send a TCP RST with the MPFASTCLOSE option itself when it releases state in order to clear any remaining state at middleboxes. o Upon receipt of a RST with MPFASTCLOSE, containing the valid key, Host B tears down all subflows. Host B can now close the whole MPTCP connection (it transitions directly to CLOSED state). The burden of the MP_FASTCLOSE is on the host that decides to close the connection (typically the server, but not necessarily). The text above allows it to opt for either ACK or RST without adding complexity to the other side. Another point that might be discussed in RFC6824bis is how a host should react when there are all the subflows associates to a Multipath TCP connection are in the CLOSED state, but the connection is still alive. At this point, it is impossible to send or receive data over the connection. It should attempt to reestablish one subflow to keep the connection alive. Olivier