Crate decdn_protocol 

The deCDN wire protocol: the ALPN identifiers, the message types each ALPN carries, and the framing that puts them on a QUIC stream.

deCDN speaks three ALPNs (ADR 005):

ALPN	Constant	Messages	Purpose
cdn/probe/v1	ALPN_PROBE	ProbeMessage	Latency and availability probing
cdn/client/v1	ALPN_CLIENT	ClientMessage	All paid delivery, client to node and node to node
cdn/dht/v1	ALPN_DHT	DhtMessage	Content discovery over a Kademlia DHT (ADR 022)

Modules

Module	Contents
framing	The length-prefixed frame, encode_message / decode_message, and the async read_frame / write_frame
message	cdn/probe/v1: ProbeRequest, ProbeResponse
client	cdn/client/v1: StreamRequest, StreamResponse, ChunkData, the wire Voucher, StreamError
dht	cdn/dht/v1: store and find requests, provider records, closer-node lists
coverage	The block coverage bitmap a partial holder advertises
identity	The 32-byte NodeId and ContentHash newtypes
region	ISO 3166-1 alpha-2 Region codes

Frames and extensions

Every message is a postcard encoding behind a varint length prefix, capped at MAX_MESSAGE_SIZE (ADR 013 § Wire Framing). A signed message has a frozen base: the fields its signature covers. Unsigned fields travel as trailing bytes after the base. decode_message returns them as a remainder, and the parse_*_ext functions read them (ADR 013 § Three Tiers of Evolution).

use decdn_protocol::{ProbeMessage, ProbeRequest, decode_message, encode_message};

let request = ProbeMessage::Request(ProbeRequest {
    hash: [7; 32],
    timestamp_us: 1_700_000_000_000_000,
});
let frame = encode_message(&request)?;
let (decoded, remainder) = decode_message::<ProbeMessage>(&frame)?;
assert_eq!(decoded, request);
assert!(remainder.is_empty());

This crate holds no cryptography. The signatures carried in these messages are made and checked by decdn-incentive. It has few dependencies, so code that only speaks the protocol links no blob store, Ethereum client, or cloud SDK.

Re-exports

pub use client::BINDING_SIG_LEN;

pub use client::CHUNK_BYTES;

pub use client::ChunkData;

pub use client::ChunkPreimage;

pub use client::ClientBinding;

pub use client::ClientMessage;

pub use client::MAX_CHAIN_LENGTH;

pub use client::MB_BYTES;

pub use client::StreamError;

pub use client::StreamRequest;

pub use client::StreamRequestExt;

pub use client::StreamResponse;

pub use client::StreamResponseBody;

pub use client::StreamResponseExt;

pub use client::VOUCHER_SIG_LEN;

pub use client::Voucher;

pub use client::VoucherRejectReason;

pub use client::encode_chunk_frame;

pub use client::encode_stream_request;

pub use client::encode_stream_response;

pub use client::parse_stream_request_ext;

pub use client::parse_stream_response_ext;

pub use coverage::Coverage;

pub use coverage::DISCOVERY_BLOCK_BYTES;

pub use coverage::discovery_block_bytes;

pub use coverage::num_blocks;

pub use dht::BatchStoreAck;

pub use dht::BatchStoreRequest;

pub use dht::CloserNodes;

pub use dht::CloserNodesError;

pub use dht::DhtMessage;

pub use dht::FindNodeRequest;

pub use dht::FindNodeResponse;

pub use dht::FindValueRequest;

pub use dht::FindValueResponse;

pub use dht::FindValueResponseExt;

pub use dht::MAX_BATCH_STORE_HASHES;

pub use dht::MAX_CLOSER_NODES;

pub use dht::MAX_PROVIDERS_PER_HASH;

pub use dht::StoreAck;

pub use dht::StoreRequest;

pub use dht::StoreRequestExt;

pub use dht::encode_find_value_response;

pub use dht::encode_store_request;

pub use dht::parse_find_value_response_ext;

pub use dht::parse_store_request_ext;

pub use framing::FrameError;

pub use framing::MAX_MESSAGE_SIZE;

pub use framing::TopLevelEnum;

pub use framing::decode_message;

pub use framing::encode_message;

pub use framing::is_unknown_variant;

pub use framing::read_frame;

pub use framing::write_frame;

pub use identity::ContentHash;

pub use identity::ID_LEN;

pub use identity::NodeId;

pub use message::MAX_RATE_PER_MB;

pub use message::MessageValidationError;

pub use message::ProbeMessage;

pub use message::ProbeRequest;

pub use message::ProbeResponse;

pub use message::ProbeResponseBody;

pub use message::ProbeResponseExt;

pub use message::SLASH_SIG_LEN;

pub use message::encode_probe_response;

pub use message::parse_probe_response_ext;

pub use region::InvalidRegion;

pub use region::Region;

pub use region::is_valid_region;

Modules

client

Wire message payload types for the cdn/client/v1 paid-delivery protocol.

coverage

Range-keyed block coverage bitmap (ADR 039-adjacent partial-holder discovery).

dht

Wire message types for the cdn/dht/v1 Kademlia content DHT (ADR 022).

framing

Length-prefixed wire framing for deCDN ALPNs (ADR 013).

identity

Strongly-typed 32-byte identity newtypes for the deCDN wire protocol.

message

Wire message payload types for deCDN ALPN protocols.

region

ISO 3166-1 alpha-2 region-code validation.

Constants

ALPN_CLIENT

ALPN protocol identifier for paid blob delivery (client-to-node and node-to-node).

ALPN_DHT

ALPN protocol identifier for Kademlia-based content discovery (ADR 022).

ALPN_PROBE

ALPN protocol identifier for latency and availability probing.

APP_ERR_RATE_LIMITED

Connection rejected by the per-source or global rate limiter (ADR 013 §0x10).