Enum CursorError 

pub enum CursorError {
    Expired,
    InvalidSignature,
    Format(String),
    TooLarge(usize),
    OpaqueStateTooLarge(usize),
}

Errors from cursor issue / verify operations.

Variants

Expired

Cursor’s issued_at_unix is older than ttl_seconds, or its server_session doesn’t match the current issuer (server restarted). Maps to ERR_CURSOR_EXPIRED on the wire.

InvalidSignature

HMAC verification failed AND the cursor’s embedded server_session matches the current issuer’s nonce. This narrows the cause to real forgery / tampering: an attacker constructed a body whose nonce happened to match (or, with probability 2⁻⁶⁴, key rotation that preserved the nonce). Maps to ERR_CURSOR_INVALID on the wire — adopters should surface as a security signal.

Server restart (random key AND random nonce both rotated) is the expected lifecycle of single-instance deployments and is reported as Self::Expired instead, so adopters can transparently drop the persisted cursor and re-issue.

Format(String)

Malformed encoding (bad base64, bad CBOR). Maps to ERR_CURSOR_INVALID.

TooLarge(usize)

Encoded cursor exceeds MAX_CURSOR_BYTES. Returned only on issue (verify checks the same cap before decoding).

OpaqueStateTooLarge(usize)

opaque_state exceeds MAX_OPAQUE_STATE_BYTES. Caught at issue time so a tool can’t accidentally embed a 1MB blob.

Trait Implementations

impl Debug for CursorError

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

Formats the value using the given formatter.

impl Display for CursorError

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

Formats the value using the given formatter.

impl Error for CursorError

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.