Enum Tag 

#[non_exhaustive]
pub enum Tag {
    Boolean,
    Integer,
    BitString,
    OctetString,
    Null,
    ObjectIdentifier,
    Real,
    Enumerated,
    Utf8String,
    Sequence,
    Set,
    NumericString,
    PrintableString,
    TeletexString,
    VideotexString,
    Ia5String,
    UtcTime,
    GeneralizedTime,
    VisibleString,
    BmpString,
    Application {
        constructed: bool,
        number: TagNumber,
    },
    ContextSpecific {
        constructed: bool,
        number: TagNumber,
    },
    Private {
        constructed: bool,
        number: TagNumber,
    },
}

ASN.1 tags.

Tags are the leading identifier octet of the Tag-Length-Value encoding used by ASN.1 DER and identify the type of the subsequent value.

They are described in X.690 Section 8.1.2: Identifier octets, and structured as follows:

| Class | P/C | Tag Number |

• Bits 8/7: Class
• Bit 6: primitive (0) or constructed (1)
• Bits 5-1: tag number

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Boolean

BOOLEAN tag: 1.

Integer

INTEGER tag: 2.

BitString

BIT STRING tag: 3.

OctetString

OCTET STRING tag: 4.

Null

NULL tag: 5.

ObjectIdentifier

OBJECT IDENTIFIER tag: 6.

Real

REAL tag: 9.

Enumerated

ENUMERATED tag: 10.

Utf8String

UTF8String tag: 12.

Sequence

SEQUENCE tag: 16.

Set

SET and SET OF tag: 17.

NumericString

NumericString tag: 18.

PrintableString

PrintableString tag: 19.

TeletexString

TeletexString tag: 20.

VideotexString

VideotexString tag: 21.

Ia5String

IA5String tag: 22.

UtcTime

UTCTime tag: 23.

GeneralizedTime

GeneralizedTime tag: 24.

VisibleString

VisibleString tag: 26.

BmpString

BMPString tag: 30.

Application

Application tag.

Fields

constructed: bool

Is this tag constructed? (vs primitive).

number: TagNumber

Tag number.

ContextSpecific

Context-specific tag.

Fields

constructed: bool

Is this tag constructed? (vs primitive).

number: TagNumber

Tag number.

Private

Private tag number.

Fields

constructed: bool

Is this tag constructed? (vs primitive).

number: TagNumber

Tag number.

Implementations

impl Tag

pub fn assert_eq(self, expected: Tag) -> Result<Tag>

Assert that this Tag matches the provided expected tag.

On mismatch, returns an Error with ErrorKind::TagUnexpected.

pub fn class(self) -> Class

Get the Class that corresponds to this Tag.

pub fn number(self) -> TagNumber

Get the TagNumber (lower 6-bits) for this tag.

pub fn is_constructed(self) -> bool

Does this tag represent a constructed (as opposed to primitive) field?

pub fn is_application(self) -> bool

Is this an application tag?

pub fn is_context_specific(self) -> bool

Is this a context-specific tag?

pub fn is_private(self) -> bool

Is this a private tag?

pub fn is_universal(self) -> bool

Is this a universal tag?

pub fn octet(self) -> u8

Get the octet encoding for this Tag.

pub fn length_error(self) -> Error

Create an Error for an invalid Length.

pub fn non_canonical_error(self) -> Error

Create an Error for an non-canonical value with the ASN.1 type identified by this tag.

pub fn unexpected_error(self, expected: Option<Self>) -> Error

Create an Error because the current tag was unexpected, with an optional expected tag.

pub fn value_error(self) -> Error

Create an Error for an invalid value with the ASN.1 type identified by this tag.

Trait Implementations

impl Clone for Tag

fn clone(&self) -> Tag

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Tag

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

Formats the value using the given formatter.

impl<'a> Decode<'a> for Tag

fn decode<R: Reader<'a>>(reader: &mut R) -> Result<Self>

Attempt to decode this message using the provided decoder.

fn from_der(bytes: &'a [u8]) -> Result<Self>

Parse Self from the provided DER-encoded byte slice.

impl DerOrd for Tag

fn der_cmp(&self, other: &Self) -> Result<Ordering>

Return an Ordering between self and other when serialized as ASN.1 DER.

impl Display for Tag

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

Formats the value using the given formatter.

impl Encode for Tag

fn encoded_len(&self) -> Result<Length>

Compute the length of this value in bytes when encoded as ASN.1 DER.

fn encode(&self, writer: &mut impl Writer) -> Result<()>

Encode this value as ASN.1 DER using the provided Writer.

fn encode_to_slice<'a>(&self, buf: &'a mut [u8]) -> Result<&'a [u8]>

Encode this value to the provided byte slice, returning a sub-slice containing the encoded message.

fn encode_to_vec(&self, buf: &mut Vec<u8>) -> Result<Length>

Available on crate feature alloc only.

Encode this message as ASN.1 DER, appending it to the provided byte vector.

fn to_der(&self) -> Result<Vec<u8>>

Available on crate feature alloc only.

Encode this type as DER, returning a byte vector.

impl From<&Tag> for u8

fn from(tag: &Tag) -> u8

Converts to this type from the input type.

impl From<Tag> for u8

fn from(tag: Tag) -> u8

Converts to this type from the input type.

impl Ord for Tag

fn cmp(&self, other: &Tag) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Tag

fn eq(&self, other: &Tag) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Tag

fn partial_cmp(&self, other: &Tag) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TryFrom<u8> for Tag

type Error = Error

The type returned in the event of a conversion error.

fn try_from(byte: u8) -> Result<Tag>

Performs the conversion.

impl Copy for Tag

impl Eq for Tag

impl StructuralPartialEq for Tag

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 3 bytes

Size for each variant:

• Boolean: 0 bytes
• Integer: 0 bytes
• BitString: 0 bytes
• OctetString: 0 bytes
• Null: 0 bytes
• ObjectIdentifier: 0 bytes
• Real: 0 bytes
• Enumerated: 0 bytes
• Utf8String: 0 bytes
• Sequence: 0 bytes
• Set: 0 bytes
• NumericString: 0 bytes
• PrintableString: 0 bytes
• TeletexString: 0 bytes
• VideotexString: 0 bytes
• Ia5String: 0 bytes
• UtcTime: 0 bytes
• GeneralizedTime: 0 bytes
• VisibleString: 0 bytes
• BmpString: 0 bytes
• Application: 2 bytes
• ContextSpecific: 2 bytes
• Private: 2 bytes