Struct bsn1::BerBuilder

pub struct BerBuilder { /* fields omitted */ }

BerBuilder is a struct to build Ber effectively.

Examples

Definite length and empty contents.

use bsn1::{Ber, BerBuilder, IdRef, Length};

let id = IdRef::octet_string();

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

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

assert_eq!(expected, ber);

Indefinite length and empty contents.

use bsn1::{Ber, BerBuilder, IdRef, Length};

let id = IdRef::octet_string();
let eoc = Ber::new(IdRef::eoc(), &[]);

// Because the contents is empty, do not need to call method 'extend_contents()'.
// Function 'finish()' will adds the last 'EOC.'
let mut builder = BerBuilder::new(id, Length::Indefinite);
let ber = builder.finish();

assert_eq!(id, ber.id());
assert_eq!(Length::Indefinite, ber.length());
assert_eq!(eoc.as_ref() as &[u8], ber.contents());

Definite length and not empty contents.

use bsn1::{Ber, BerBuilder, IdRef, Length};

let id = IdRef::octet_string();

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

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

    assert_eq!(expected, ber);
}

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

    assert_eq!(expected, ber);
}

Indefinite length and not empty contents.

use bsn1::{Ber, BerBuilder, IdRef, Length};

let id = IdRef::octet_string();
let contents: &[u8] = &[0, 1, 2, 3, 4];
let eoc = Ber::new(IdRef::eoc(), &[]);

// Append 'contents' at once.
{
    let length = Length::Indefinite;
    let mut builder = BerBuilder::new(id, length);
    unsafe { builder.extend_contents(contents) };
    let ber = builder.finish();

    assert_eq!(id, ber.id());
    assert_eq!(Length::Indefinite, ber.length());

    let mut bytes = Vec::from(contents);
    bytes.extend(eoc.as_ref() as &[u8]);
    let bytes: &[u8] = bytes.as_ref();
    assert_eq!(bytes, ber.contents());
}

// Split contents into 2 pieces and append them one by one.
{
    let length = Length::Indefinite;
    let mut builder = BerBuilder::new(id, length);
    unsafe {
        builder.extend_contents(&contents[..2]);
        builder.extend_contents(&contents[2..]);
    }
    let ber = builder.finish();

    assert_eq!(id, ber.id());
    assert_eq!(Length::Indefinite, ber.length());

    let mut bytes = Vec::from(contents);
    bytes.extend(eoc.as_ref() as &[u8]);
    let bytes: &[u8] = bytes.as_ref();
    assert_eq!(bytes, ber.contents());
}

Implementations

impl BerBuilder

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 .

Examples

See examples for the struct .

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

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

Warnings

The user must not adds 'EOC' if Length::Indefinite was passed to the constructor funciton new . Function finish will adds the last 'EOC.' (Indefinite length BER must include one and only one 'EOC' in the contents.)

Safety

The behavior is undefined if user appends 'EOC' to a Indefinite length builder instance.

Panics

Panics if Length::Definite was passed to the constructor new , and if the accumerated length of the 'contents' will exceed that value.

Examples

See examples for the struct .

pub fn finish(self) -> Ber

Consumes self , building a new Ber instance.

If Length::Indefinite was passed to the constructor new , this method adds 'EOC' to the end of contents of a building Ber .

Panics

Panics if Length::Definite was passed to the constructor new , and if the accumerated length of the 'contents' does not equal to that value.

Examples

See examples for the struct .