Crate sctp_proto 

Low-level protocol logic for the SCTP protocol

sctp-proto contains a fully deterministic implementation of SCTP protocol logic. It contains no networking code and does not get any relevant timestamps from the operating system. Most users may want to use the futures-based sctp-async API instead.

The main entry point is Endpoint, which manages associations for a single socket. Use Endpoint::connect to initiate outgoing associations, or provide a ServerConfig to accept incoming ones. Incoming UDP datagrams are fed to Endpoint::handle, which either creates a new Association or returns an event to pass to an existing one.

Association holds the protocol state for a single SCTP association. It produces Events and outgoing packets via polling methods (Association::poll, Association::poll_transmit). Each association contains multiple Streams for reading and writing data.

Status

This crate is maintained by the str0m project, which has been using it since January 2023. Other consumers include ex_sctp for Elixir WebRTC. The crate is kept in sync with rtc-sctp where possible to share bug fixes.

Originally written by Rain Liu as a Sans-IO implementation of SCTP for the webrtc-rs ecosystem, this crate predates rtc-sctp in the webrtc-rs/rtc monorepo, which was later derived from this work. Maintenance was transferred to the str0m maintainers in January 2026.

Structs

Association

Association represents an SCTP association

AssociationEvent

Events sent from an Endpoint to an Association

AssociationHandle

Internal identifier for an Association currently associated with an endpoint

AssociationStats

Association statistics

Chunk

A chunk of data from the stream

ChunkPayloadData

ChunkPayloadData represents an SCTP Chunk of type DATA

Chunks

Chunks is a set of chunks that share the same SSN

ClientConfig

Configuration for outgoing associations

Endpoint

The main entry point to the library

EndpointConfig

Global configuration for the endpoint, affecting all associations

EndpointEvent

Events sent from an Association to an Endpoint

ErrorCauseCode

ErrorCauseCode is a cause code that appears in either a ERROR or ABORT chunk

ServerConfig

Parameters governing incoming associations

Stream

Stream represents an SCTP stream

StreamState

StreamState represents the state of an SCTP stream

Transmit

Incoming/outgoing Transmit

TransportConfig

Config collects the arguments to create_association construction into a single structure

Enums

AssociationError

Reasons why an association might be lost

ConnectError

Errors in the parameters being used to create a new association

DatagramEvent

Event resulting from processing a single datagram

EcnCodepoint

Explicit congestion notification codepoint

Error

Errors triggered during SCTP association operation

Event

Events of interest to the application

Payload

Payload in Incoming/outgoing Transmit

PayloadProtocolIdentifier

PayloadProtocolIdentifier is an enum for DataChannel payload types

ReliabilityType

Reliability type for stream

Side

Whether an endpoint was the initiator of an association

StreamEvent

Application events about streams

Type Aliases

AssociationId

Protocol-level identifier for an Association.

StreamId

Identifier for a stream within a particular association