Enum ConnectionError 

pub enum ConnectionError {
    Endpoint(EndpointError),
    Codec(CodecError),
    Transport(TransportError),
    VarInt(VarIntError),
    NoControlStream,
    UnexpectedEnd,
    StreamFinished,
    InvalidAddress(String),
    TlsConfig(String),
    DataStreamState(&'static str),
    ControlMessageNarrowing,
    RequestOnControlStream(MessageType),
    RequestStreamMessageOnControlStream(MessageType),
    PayloadOnStatusDatagram {
        object_id: u64,
        payload_len: usize,
        status: Option<ObjectStatus>,
    },
    PropertiesOnNonNormalStatus {
        object_id: u64,
        properties_len: usize,
        status: ObjectStatus,
    },
    NonRequestOnRequestStream(MessageType),
    RespondedToOwnRequest(u64),
    FinBeforeResponse(u64),
    FinBeforePublishDone(u64),
}

Errors from the connection layer.

Variants

Endpoint(EndpointError)

Endpoint state machine error.

Codec(CodecError)

Wire codec error.

Transport(TransportError)

Transport-level error.

VarInt(VarIntError)

Variable-length integer decoding error.

NoControlStream

Control stream was not opened.

UnexpectedEnd

Stream ended before a complete message was read.

StreamFinished

Stream was finished by the peer.

InvalidAddress(String)

Invalid server address string.

TlsConfig(String)

TLS configuration error.

DataStreamState(&'static str)

Data stream used out of order (e.g. object before header).

ControlMessageNarrowing

A control message this build decoded for draft-21 and then could not narrow to draft-21’s own message type.

Unreachable, and that is not the same as harmless. read_control decodes with this connection’s own draft, so the AnyControlMessage it hands back can only carry this draft’s variant — but the narrowing arm is compiled in every configuration anyway, under #[allow(unreachable_patterns)] rather than a cfg naming the other drafts, because such a list has to be edited in every per-draft module whenever a draft is added and a copy that omits one leaves the match non-exhaustive.

Spelled as CodecError::UnknownMessageType(0) it would not stay inert: every draft’s codec_session_error_code answers that variant Some(PROTOCOL_VIOLATION). So the day the narrowing did fail, this build’s own defect would reach a caller as the peer sent a control message type this draft does not assign, and the session must be closed with a Protocol Violation — carrying 0x00 as the codepoint that proved it. A conformance report reading that publishes a named, well-evidenced accusation against a relay for something no relay did.

A variant of its own is what stops that. draft_specific_cause answers it LocalRefusal, the facade turns that into ErrorCause::Facade, and nothing downstream can read a rule out of a cause that says nothing reached the wire. What is pinned is the consequence rather than the unreachability: nothing pins the arm’s reachability, which is exactly why the consequence must not be an accusation.

RequestOnControlStream(MessageType)

A message that begins a request stream was handed to Connection::send_control. Nothing was written.

RequestStreamMessageOnControlStream(MessageType)

A message draft-21 places on a request stream was handed to Connection::send_control. Nothing was written.

Distinct from ConnectionError::RequestOnControlStream, which is about a message that would begin a request stream of its own. This one is about a message that belongs on a request stream already open, and so has no meaning without one around it.

PayloadOnStatusDatagram

A datagram carrying an Object Status arrived with bytes after its header. Draft-21 Section 11.1.2: “An Object MUST have an empty payload unless its Object Status value is registered as permitting a payload in the Object Status registry” Section 11.2.1 says the same thing about the framing: a datagram with the STATUS bit set “is present and there is no Object Payload.”

The codec cannot see this. DatagramHeader::decode stops at the end of the header and never owns the datagram’s tail, so the only layer that holds both the status and the bytes after it is this one. Without the check the application is handed, say, an End-of-Group object carrying four bytes of payload — a combination the draft forbids outright.

Recoverable: the drafts state the rule as a property of a conforming object, not as one of the “MUST close the session” cases, so the datagram is refused and the session left running.

Fields

object_id: u64

Object ID from the datagram header.

payload_len: usize

How many bytes followed the header.

status: Option<ObjectStatus>

The status the header declared.

Spelled out in full because the glob import of moqtap_codec::types brings a different ObjectStatus into this module.

PropertiesOnNonNormalStatus

An Object arrived carrying properties on a status that is not Normal.

Draft-21 Section 11.1.3: “Any Object with status Normal can have properties (Section 8.4). If an endpoint receives properties on an Object with status that is not Normal, it MUST close the session with a PROTOCOL_VIOLATION.”

The codec decodes such an Object rather than refusing it — the frame is well formed, and a tool that reports non-conforming traffic has to be able to read it. Being an endpoint rather than an observer is what turns it into an error, so it is raised here, on the receive path, and not in the decoder.

Fields

object_id: u64

The Object ID the properties arrived on.

properties_len: usize

Length in bytes of the properties block.

status: ObjectStatus

The Object’s status, resolved through the encoding’s elision rule.

Spelled out in full because the glob import of moqtap_codec::types brings a different ObjectStatus into this module.

NonRequestOnRequestStream(MessageType)

A bidirectional stream the peer opened began with a message type that does not open a request stream.

Draft-21 Section 6.3: “Bidirectional streams MUST NOT begin with any other message type unless negotiated. If they do, the peer MUST close the Session with a PROTOCOL_VIOLATION.” The session has already been closed on the wire by the time this is returned, and the offending stream reset.

RespondedToOwnRequest(u64)

A respond_* helper was handed a request stream this endpoint opened. Nothing was written and no state moved.

FinBeforeResponse(u64)

RequestStream::finish was called on a request stream the peer opened before a response had been written on it. Nothing was written.

Draft-21 Section 6.4.2.2: “An endpoint MUST NOT send a FIN on a direction of a request stream until it has sent all required messages on that direction for its request type. In particular, an endpoint sending a response to a request MUST send the corresponding response message … before sending a FIN.” The section arrived in draft-19 and draft-21 keeps it verbatim; drafts 17 and 18 have no such rule and no such guard.

FinBeforePublishDone(u64)

RequestStream::finish was called on a subscription this endpoint is the publisher of, before PUBLISH_DONE. Nothing was written.

The second half of the same sentence in draft-21 Section 6.4.2.2: “the publisher of an Established subscription MUST send PUBLISH_DONE, before sending a FIN.” It applies to the accepted SUBSCRIBE a responder answered with SUBSCRIBE_OK and to the PUBLISH this endpoint sent, which is why Connection::publish_done and Connection::publish_done_on are the only routes that clear it.

Trait Implementations

impl Debug for ConnectionError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ConnectionError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for ConnectionError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<CodecError> for ConnectionError

fn from(source: CodecError) -> Self

Converts to this type from the input type.

impl From<ConnectionError> for AnyConnectionError

Available on crate feature draft21 only.

fn from(err: ConnectionError) -> Self

Converts to this type from the input type.

impl From<DialError> for ConnectionError

fn from(e: DialError) -> Self

Maps a dial failure onto the variants this error already has, so a caller matches InvalidAddress or TlsConfig.

LocalSocket joins InvalidAddress, and that is the answer being kept

A socket this machine would not open has a variant of its own on DialError, and it still arrives here. Not laziness about the churn — InvalidAddress is one of the variants the facade reads as ErrorCause::Facade, which is_local answers true for, and a failed bind is this side’s by definition. Routing it to Transport would read better in prose and would publish this machine’s missing IPv6 stack as the relay’s doing.

The phase is not lost, only unread on this path. A caller measuring which stage of a dial died reads DialError::phase off the dial itself; a caller who arrived at this type named a host:port and asked for a connection, not for a measurement, and a public variant here for a distinction nothing on this path reads is churn with no reader, which is why this impl stays flat.

impl From<EndpointError> for ConnectionError

fn from(source: EndpointError) -> Self

Converts to this type from the input type.

impl From<TransportError> for ConnectionError

fn from(source: TransportError) -> Self

Converts to this type from the input type.

impl From<VarIntError> for ConnectionError

fn from(source: VarIntError) -> Self

Converts to this type from the input type.