Module draft23 

MoQT wire codec for draft-23.

The ALPN is moqt-23. The draft-23 wire format:

• The control message Length is a vi64 (Section 9, Figure 6) and is bounded by the receiver’s MAX_CONTROL_MESSAGE_SIZE, Setup Option 0x09 (Section 9.1.8), 65535 unless advertised higher. 0x09 is odd, so its value is a Length and one vi64.
• FETCH is answered by REQUEST_OK. Type 0x18 is “RESERVED (FETCH_OK in <= 22)” (Table 5). A FETCH_OK may carry EXPIRES and LARGEST_OBJECT and Track Properties (Section 9.3).
• REQUEST_ERROR ends in Error Details, Key-Value-Pairs (Section 9.4.1): REDIRECT 0x01, which MUST accompany Error Code REDIRECT, and UNSUPPORTED_PROPERTY 0x02 (Section 9.4.2.1, Section 9.4.2.2).
• NAMESPACE carries a parameter block (Section 9.15, Figure 20).
• FILL_PARAMETERS (0x23) is a count, not a length (Section 9.19.15), and may appear in PUBLISH and SUBSCRIBE_TRACKS.
• PAUSED (0x11), default 0 (Section 9.19.18), and SUBSCRIBE_TRACKS_ID (0x36) (Section 9.19.21).
• A Track Name MUST NOT be empty (Section 2.4.1).
• Fetch streams: an Object ID Delta in the same Group adds delta + 2 (Section 11.4.1.1); End of Range indicators are delta encoded (Section 11.4.2.1); Table 8 adds End of Gone Range 0x40C, End of Group 0x80 and End of Track 0x81.
• Session termination codes 0x200-0x203, 0x300-0x306 and 0x400-0x401, and 0x6 MALFORMED_KEY_VALUE (Section 12.2). REQUEST_ERROR has UNAVAILABLE 0xA and PUBLISH_DONE has EXPIRED_AUTH_TOKEN 0x7 (Section 12.3 and Section 12.4); neither REQUEST_ERROR 0x30 nor stream reset 0x6 is assigned.

Where this codec had to choose

Each decision is recorded at the site that makes it:

• MAX_CONTROL_MESSAGE_SIZE is read as Length plus exactly one vi64, and a value below 65535 is decoded as it arrived and refused on encode — message::decode_max_control_message_size
• the limit applies to the Message Length field, the body alone — message::ControlMessage::decode_with_limit
• a REDIRECT Error Detail’s Track Name may be empty, and a repeated REDIRECT detail is decoded and refused on encode — message::Redirect
• any parameter in NAMESPACE is out of scope, because no parameter definition names NAMESPACE — message::Namespace
• Object Payload Length is present on an End of Range indicator, encoded as 0, and absent on End of Group and End of Track — data_stream::FetchObjectHeader
• after End of Group or End of Track the prior Object ID is 2^64-1 for every later entry, indicators included, and either one as the first entry is refused — data_stream::FetchObjectReader

What this codec does not enforce

REQUEST_UPDATE (Section 9.5) and REQUEST_OK (Section 9.3) list their parameters per kind of request. Which list applies depends on the request the frame answers or updates, which is session state, so message::parameter_in_scope holds each to the union of its lists. message::RequestOk::check_answers applies one REQUEST_OK list and the Track Properties rule when the caller knows the request.

Modules

data_stream

Draft-23 data stream header encoding and decoding.

error_codes

Error, status and stream-reset code registries defined by draft-ietf-moq-transport-23.

fields

This draft’s field names for a decoded control message.

message

Draft-23 control message encoding and decoding.

types

Draft-23 object status values.