Struct bsn1::DerBuilder

pub struct DerBuilder { /* fields omitted */ }

DerBuilder is a struct to build Der effectively.

Examples

Empty contents.

use bsn1::{Der, DerBuilder, IdRef, Length};

let id = IdRef::octet_string();

let expected = Der::new(IdRef::octet_string(), &[]);

// Because the contents is empty, do not need to call method 'extend_contents()'.
let mut builder = DerBuilder::new(id, Length::Definite(0));
let der = builder.finish();

assert_eq!(expected, der);

Not empty contents

use bsn1::{Der, DerBuilder, IdRef, Length};

let id = IdRef::octet_string();

let contents = &[0, 1, 2, 3, 4];
let expected = Der::new(IdRef::octet_string(), contents);

// Append 'contents' at once.
{
    let length = Length::Definite(contents.len());
    let mut builder = DerBuilder::new(id, length);
    builder.extend_contents(contents);
    let der = builder.finish();

    assert_eq!(expected, der);
}

// Split contents into 2 pieces and append them one by one.
{
    let length = Length::Definite(contents.len());
    let mut builder = DerBuilder::new(id, length);
    builder.extend_contents(&contents[..2]);
    builder.extend_contents(&contents[2..]);
    let der = builder.finish();

    assert_eq!(expected, der);
}

Implementations

impl DerBuilder

pub fn new(id: &IdRef, contents_len: Length) -> Self

Creates a new instance to build Der with id and contents whose length equals to contents_len .

contents_len must be Length::Definite because DER does not allow indefinite length.

Warnings

ASN.1 does not allow some universal identifier for DER, however, this function accepts such an identifier. For example, 'Octet String' must be primitive in DER, but this function will construct a new instance even if id represenets constructed 'Octet String.'

Panics

Panics if contents_len equals Length::Indefinite .

Examples

See examples for the struct .

pub fn extend_contents<B>(&mut self, bytes: B) where
    B: AsRef<[u8]>, 

Appends bytes to the end of the DER contents to be build.

Panics

Panics if the accumerated length of the 'contents' exceeds contents_len passed to the constructor function new as the argument.

Examples

See examples for the struct .

pub fn finish(self) -> Der

Consumes self , building a new Der .

Panics

Panics if the accumerated length of the 'contents' differs from contents_len passed to the constructor function new as the argument.

Examples

See examples for the struct .