Module data_stream 

Draft-23 data stream header encoding and decoding.

Subgroup Type Flags: form 0b0XX1XXXX, so bit 4 is set and bit 7 is clear; the ranges are 0x10..0x1F, 0x30..0x3F, 0x50..0x5F, 0x70..0x7F.

• bit 0 (0x01): PROPERTIES
• bits 1-2 (0x06): SUBGROUP_ID_MODE (0=zero, 1=first_obj, 2=explicit, 3=reserved)
• bit 3 (0x08): END_OF_GROUP
• bit 5 (0x20): DEFAULT_PRIORITY (no priority byte)
• bit 6 (0x40): FIRST_OBJECT

Datagram Type Flags: 0b00X0XXXX, so bits 4, 6 and 7 are clear; the ranges are 0x00..0x0F and 0x20..0x2F.

• bit 0 (0x01): PROPERTIES
• bit 1 (0x02): END_OF_GROUP
• bit 2 (0x04): ZERO_OBJECT_ID (object_id=0, field omitted)
• bit 3 (0x08): DEFAULT_PRIORITY (no priority byte)
• bit 5 (0x20): STATUS (status byte replaces payload)

Section 11.3.1 and Section 11.2.1 each list the Type Flags values an endpoint refuses with INVALID_STREAM_HEADER, and the two lists differ: bit 4 MUST be 1 on a subgroup header and 0 on a datagram. A non-minimally encoded Type Flags value is accepted on receive and never emitted.

An Object has an empty payload unless its status is registered as permitting one (Section 11.1.1); SubgroupObjectReader::write_object refuses a payload its status forbids.

Fetch stream: stream type 0x05 + Request ID, then entries whose leading Serialization Flags say which fields follow (Section 11.4.1). FetchObjectHeader decodes one entry and FetchObjectReader resolves its IDs. Table 8 has six indicators: four End of Range values and End of Group and End of Track.

Re-exports

use bytes::Buf; 🔒

use bytes::BufMut; 🔒

use super::types::ObjectStatus; 🔒

use super::types::PayloadPermission; 🔒

use crate::error::CodecError; 🔒

use crate::object_properties::ObjectProperty; 🔒

use crate::object_properties::PropertyValue; 🔒

use crate::varint::Moqt18 as Wire; 🔒

use crate::varint::VarInt; 🔒

Structs

DatagramHeader

FetchGaps

The Prior Group ID Gap and Prior Object ID Gap conditions of draft-23 Section 10.8 and draft-23 Section 10.9 that one fetch stream shows.

FetchHeader

The head of a fetch stream: the stream type 0x05 and a Request ID.

FetchObject

One entry from a FETCH stream with its delta-encoded fields resolved.

FetchObjectHeader

One entry on a draft-23 fetch stream, up to but not including its payload.

FetchObjectLayout 🔒

Which fields a Serialization Flags value puts on the wire.

FetchObjectReader

Resolves the delta-encoded fields of the entries on one FETCH stream.

FetchObjectWriter

Re-encodes resolved fetch entries onto one FETCH stream.

PriorGaps

The Prior Group ID Gap and Prior Object ID Gap one Object carries.

SubgroupHeader

SubgroupObject

One object within a draft-23 subgroup stream. Object IDs are delta-encoded; whether a per-object “properties” block (the draft-23 equivalent of extension headers) is present depends on the PROPERTIES bit on the enclosing SubgroupHeader. Use SubgroupObjectReader to encode/decode.

SubgroupObjectMeta

The framing of one draft-23 subgroup object, without its payload.

SubgroupObjectReader

Enums

FetchEndMarker

An indicator that ends a Group or the Track rather than a range.

FetchEndOfRange

What an End of Range indicator says about the Locations it covers.

GroupOrder

The order a FETCH response’s Groups arrive in, which decides how a Group ID Delta is applied.

Constants

DATAGRAM_DEFAULT_PRIORITY_BIT 🔒

DATAGRAM_END_OF_GROUP_BIT 🔒

DATAGRAM_PROPERTIES_BIT 🔒

DATAGRAM_RESERVED_BIT 🔒

Bit 4. Draft-23 Section 11.2.1: “This bit is reserved and MUST be zero.” The opposite of Section 11.3.1, where the same bit MUST be 1.

DATAGRAM_SPECIFIED_BITS 🔒

Every bit draft-23 Section 11.2.1 gives a datagram Type Flags value a meaning for: PROPERTIES, END_OF_GROUP, ZERO_OBJECT_ID, DEFAULT_PRIORITY and STATUS. Bit 4 is reserved and bits 6 and up are unspecified, so both fail the mask.

DATAGRAM_STATUS_BIT 🔒

DATAGRAM_ZERO_OBJECT_ID_BIT 🔒

FETCH_DATAGRAM_BIT 🔒

Table 10 flag: the Object’s Delivery Mode is Datagram, so it has no Subgroup ID and the two low bits are to be ignored.

FETCH_END_OF_GONE_RANGE 🔒

Table 8: End of Gone Range. The two-byte 84 0C.

FETCH_END_OF_GROUP 🔒

Table 8: End of Group.

FETCH_END_OF_NON_EXISTENT_RANGE 🔒

Table 8: End of Non-Existent Range.

FETCH_END_OF_TIMED_OUT_RANGE 🔒

Table 8: End of Timed-Out Range.

FETCH_END_OF_TRACK 🔒

Table 8: End of Track.

FETCH_END_OF_UNKNOWN_RANGE 🔒

Table 8: End of Unknown Range.

FETCH_FLAGS_MAX 🔒

The largest Serialization Flags value whose bits are flags. Section 11.4.1: “When less than 128, the bits represent flags described in Section 11.4.1.1.”

FETCH_GROUP_ID_DELTA_BIT 🔒

Table 10 flag: a Group ID Delta field is present.

FETCH_OBJECT_ID_DELTA_BIT 🔒

Table 10 flag: an Object ID Delta field is present.

FETCH_PRIORITY_BIT 🔒

Table 10 flag: a Publisher Priority field is present.

FETCH_PROPERTIES_BIT 🔒

Table 10 flag: a Properties field is present.

FETCH_STREAM_TYPE 🔒

FETCH_SUBGROUP_ID_EXPLICIT 🔒

Subgroup ID mode 0b11: an explicit Subgroup ID field is on the wire.

FETCH_SUBGROUP_ID_MODE_MASK 🔒

Serialization Flags bits 0-1, the Subgroup ID encoding (draft-23 Section 11.4.1.1, Table 9).

PADDING_DATAGRAM_TYPE

Datagram type for padding, draft-23 Section 11.5.2: “An endpoint MAY send a datagram with a type of 0x132B3E29 to send padding data. The datagram contains the type followed by zero or more bytes that MUST all be set to zero.”

PADDING_STREAM_TYPE

Unidirectional stream type for padding, draft-23 Section 11.5.1: “An endpoint MAY open a unidirectional stream with a stream type of 0x132B3E28 to send padding data. The stream begins with the stream type, followed by zero or more bytes that MUST all be set to zero.”

PRIOR_GROUP_ID_GAP

Prior Group ID Gap, Object Property Type 0x3C (Section 10.8).

PRIOR_OBJECT_ID_GAP

Prior Object ID Gap, Object Property Type 0x3E (Section 10.9).

SETUP_STREAM_TYPE 🔒

The unidirectional stream Type draft-23 Section 9.1 gives the control stream.

SUBGROUP_BASE_BIT 🔒

SUBGROUP_DEFAULT_PRIORITY_BIT 🔒

SUBGROUP_END_OF_GROUP_BIT 🔒

SUBGROUP_FIRST_OBJECT_BIT 🔒

SUBGROUP_ID_MODE_MASK 🔒

SUBGROUP_ID_MODE_RESERVED 🔒

The SUBGROUP_ID_MODE value draft-23 reserves, once the mask is applied and the field shifted down.

SUBGROUP_PROPERTIES_BIT 🔒

Functions

collect_gaps 🔒

datagram_type_error 🔒

Which failure a leading datagram Type Flags value that is not one a reader wants is.

datagram_type_is_valid 🔒

Whether raw is a datagram Type Flags value draft-23 admits.

decoded_status 🔒

Turn a wire Object Status code into an ObjectStatus, refusing one draft-23 does not assign.

malformed 🔒

overflow 🔒

skip 🔒

Advance buf past len bytes without copying them.

step_group 🔒

prior moved by delta + extra in order’s direction.

stream_type_error 🔒

Which failure a leading unidirectional stream Type that is not the one a reader wants is.

subgroup_type_is_valid 🔒

Whether raw is a subgroup Type Flags value draft-23 admits: below 128, bit 4 set, and not the reserved SUBGROUP_ID_MODE.

validate_datagram_type 🔒

Refuse a datagram Type Flags value draft-23 Section 11.2.1 lists as invalid.

validate_subgroup_type 🔒

Refuse a subgroup header Type Flags value draft-23 Section 11.3.1 lists as invalid.