Struct asn1_rs::OptTaggedParser

pub struct OptTaggedParser {
    pub class: Class,
    pub tag: Tag,
}

Helper object to parse TAGGED OPTIONAL types (explicit or implicit)

This object can be used similarly to a builder pattern, to specify the expected class and tag of the object to parse, and the content parsing function.

The content parsing function takes two arguments: the outer header, and the data.

It can be used for both EXPLICIT or IMPLICIT tagged objects by using parsing functions that expect a header (or not) in the contents.

The OptTaggedParser::from method is a shortcut to build an object with ContextSpecific class and the given tag. The OptTaggedParser::new method is more generic.

See also OptTaggedExplicit and OptTaggedImplicit for alternatives that implement FromBer/ FromDer.

Examples

To parse a [APPLICATION 0] EXPLICIT INTEGER OPTIONAL object:

use asn1_rs::{Class, FromDer, Integer, Tag, OptTaggedParser};

let bytes = &[0x60, 0x03, 0x2, 0x1, 0x2];

let (_, tagged) = OptTaggedParser::new(Class::Application, Tag(0))
                    .parse_der(bytes, |_, data| Integer::from_der(data))
                    .unwrap();

assert_eq!(tagged, Some(Integer::from(2)));

To parse a [0] IMPLICIT INTEGER OPTIONAL object:

use asn1_rs::{Error, Integer, OptTaggedParser};

let bytes = &[0xa0, 0x1, 0x2];

let (_, tagged) = OptTaggedParser::from(0)
                    .parse_der::<_, Error, _>(bytes, |_, data| Ok((&[], Integer::new(data))))
                    .unwrap();

assert_eq!(tagged, Some(Integer::from(2)));

Fields

class: Class

The expected class for the object to parse

tag: Tag

The expected tag for the object to parse

Implementations

impl OptTaggedParser

pub const fn new(class: Class, tag: Tag) -> Self

Build a new OptTaggedParser object.

If using Class::ContextSpecific, using OptTaggedParser::from with either a Tag or u32 is a shorter way to build this object.

pub const fn universal(tag: u32) -> Self

pub const fn tagged(tag: u32) -> Self

pub const fn application(tag: u32) -> Self

pub const fn private(tag: u32) -> Self

pub fn parse_ber<'a, T, E, F>(
    &self,
    bytes: &'a [u8],
    f: F
) -> ParseResult<'a, Option<T>, E> where
    F: Fn(Header<'_>, &'a [u8]) -> ParseResult<'a, T, E>,
    E: From<Error>, 

Parse input as BER, and apply the provided function to parse object.

Returns the remaining bytes, and Some(T) if expected tag was found, else None.

This function returns an error if tag was found but has a different class, or if parsing fails.

Examples

To parse a [0] EXPLICIT INTEGER OPTIONAL object:

use asn1_rs::{FromBer, Integer, OptTaggedParser};

let bytes = &[0xa0, 0x03, 0x2, 0x1, 0x2];

let (_, tagged) = OptTaggedParser::from(0)
                    .parse_ber(bytes, |_, data| Integer::from_ber(data))
                    .unwrap();

assert_eq!(tagged, Some(Integer::from(2)));

pub fn parse_der<'a, T, E, F>(
    &self,
    bytes: &'a [u8],
    f: F
) -> ParseResult<'a, Option<T>, E> where
    F: Fn(Header<'_>, &'a [u8]) -> ParseResult<'a, T, E>,
    E: From<Error>, 

Parse input as DER, and apply the provided function to parse object.

Returns the remaining bytes, and Some(T) if expected tag was found, else None.

This function returns an error if tag was found but has a different class, or if parsing fails.

Examples

To parse a [0] EXPLICIT INTEGER OPTIONAL object:

use asn1_rs::{FromDer, Integer, OptTaggedParser};

let bytes = &[0xa0, 0x03, 0x2, 0x1, 0x2];

let (_, tagged) = OptTaggedParser::from(0)
                    .parse_der(bytes, |_, data| Integer::from_der(data))
                    .unwrap();

assert_eq!(tagged, Some(Integer::from(2)));

Trait Implementations

impl Debug for OptTaggedParser

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

Formats the value using the given formatter.

impl From<Tag> for OptTaggedParser

fn from(tag: Tag) -> Self

Build a TaggedOptional object with class ContextSpecific and given tag

impl From<u32> for OptTaggedParser

fn from(tag: u32) -> Self

Build a TaggedOptional object with class ContextSpecific and given tag