Enum MqttError 

pub enum MqttError {
    Io(String),
    InvalidTopicName(String),
    InvalidTopicFilter(String),
    InvalidClientId(String),
    ConnectionError(String),
    ConnectionRefused(ReasonCode),
    ProtocolError(String),
    MalformedPacket(String),
    PacketTooLarge {
        size: usize,
        max: usize,
    },
    AuthenticationFailed,
    NotAuthorized,
    NotConnected,
    AlreadyConnected,
    Timeout,
    SubscriptionFailed(ReasonCode),
    SubscriptionDenied(SubAckReasonCode),
    UnsubscriptionFailed(ReasonCode),
    PublishFailed(ReasonCode),
    PacketIdNotFound(u16),
    PacketIdInUse(u16),
    InvalidQoS(u8),
    InvalidPacketType(u8),
    InvalidReasonCode(u8),
    InvalidPropertyId(u8),
    DuplicatePropertyId(u8),
    SessionExpired,
    KeepAliveTimeout,
    ServerShuttingDown,
    ClientClosed,
    ConnectionClosedByPeer,
    MaxConnectTime,
    TopicAliasInvalid(u16),
    ReceiveMaximumExceeded,
    WillRejected,
    ImplementationSpecific(String),
    UnsupportedProtocolVersion,
    InvalidState(String),
    ClientIdentifierNotValid,
    BadUsernameOrPassword,
    ServerUnavailable,
    ServerBusy,
    Banned,
    BadAuthenticationMethod,
    QuotaExceeded,
    PayloadFormatInvalid,
    RetainNotSupported,
    QoSNotSupported,
    UseAnotherServer,
    ServerMoved,
    SharedSubscriptionsNotSupported,
    ConnectionRateExceeded,
    SubscriptionIdentifiersNotSupported,
    WildcardSubscriptionsNotSupported,
    MessageTooLarge,
    FlowControlExceeded,
    PacketIdExhausted,
    StringTooLong(usize),
    Configuration(String),
}

Variants

Io(String)

InvalidTopicName(String)

InvalidTopicFilter(String)

InvalidClientId(String)

ConnectionError(String)

ConnectionRefused(ReasonCode)

ProtocolError(String)

MalformedPacket(String)

PacketTooLarge

Fields

size: usize

max: usize

AuthenticationFailed

NotAuthorized

NotConnected

AlreadyConnected

Timeout

SubscriptionFailed(ReasonCode)

SubscriptionDenied(SubAckReasonCode)

UnsubscriptionFailed(ReasonCode)

PublishFailed(ReasonCode)

PacketIdNotFound(u16)

PacketIdInUse(u16)

InvalidQoS(u8)

InvalidPacketType(u8)

InvalidReasonCode(u8)

InvalidPropertyId(u8)

DuplicatePropertyId(u8)

SessionExpired

KeepAliveTimeout

ServerShuttingDown

ClientClosed

ConnectionClosedByPeer

MaxConnectTime

TopicAliasInvalid(u16)

ReceiveMaximumExceeded

WillRejected

ImplementationSpecific(String)

UnsupportedProtocolVersion

InvalidState(String)

ClientIdentifierNotValid

BadUsernameOrPassword

ServerUnavailable

ServerBusy

Banned

BadAuthenticationMethod

QuotaExceeded

PayloadFormatInvalid

RetainNotSupported

QoSNotSupported

UseAnotherServer

ServerMoved

SharedSubscriptionsNotSupported

ConnectionRateExceeded

SubscriptionIdentifiersNotSupported

WildcardSubscriptionsNotSupported

MessageTooLarge

FlowControlExceeded

PacketIdExhausted

StringTooLong(usize)

Configuration(String)

Implementations

impl MqttError

pub fn is_normal_disconnect(&self) -> bool

impl MqttError

pub fn classify(&self) -> Option<RecoverableError>

Classify this error for the retry/backoff layer.

Returns Some(kind) when retrying the same operation after a delay can succeed on its own (see RecoverableError), and None when it cannot.

None covers three distinct cases, all of which a blind backoff loop would handle wrong:

• Precondition errors such as MqttError::NotConnected. These are returned whenever there is no active connection, which covers both a dropped link and calling publish/subscribe before connect or after disconnect. The remedy is re-establishing the connection, a state transition owned by the reconnect layer, not re-issuing the same packet. For a QoS 1 publish that failed because the link dropped, the intended recovery is reconnect plus resend of unacked messages on the next session, not treating the raw NotConnected as retryable here.
• Caller/permanent errors such as authentication failures, bad credentials, authorization denials, and protocol errors. Retrying is futile until the caller changes the request or their configuration.
• Connection-limit signals carried in MqttError::ConnectionError strings (see MqttError::is_aws_iot_connection_limit). These look like network resets but indicate the account/client limit was hit; immediate retry makes it worse, so they are excluded on purpose.

This is intentionally conservative: a variant only classifies as recoverable when re-issuing the identical operation is the correct response. Anything requiring a reconnect, a different request, or human intervention returns None.

pub fn is_aws_iot_connection_limit(&self) -> bool

Trait Implementations

impl Clone for MqttError

fn clone(&self) -> MqttError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MqttError

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

Formats the value using the given formatter.

impl Display for MqttError

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

Formats the value using the given formatter.

impl Error for MqttError

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<&str> for MqttError

fn from(msg: &str) -> Self

Converts to this type from the input type.

impl From<Error> for MqttError

Available on crate feature std only.

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<String> for MqttError

fn from(msg: String) -> Self

Converts to this type from the input type.