Struct Sequence

pub struct Sequence<'a> {
    pub content: Cow<'a, [u8]>,
}

The SEQUENCE object is an ordered list of heteregeneous types.

Sequences can usually be of 2 types:

• a list of different objects (SEQUENCE, usually parsed as a struct)
• a list of similar objects (SEQUENCE OF, usually parsed as a Vec<T>)

The current object covers the former. For the latter, see the SequenceOf documentation.

The Sequence object contains the (unparsed) encoded representation of its content. It provides methods to parse and iterate contained objects, or convert the sequence to other types.

Building a Sequence

To build a DER sequence:

• if the sequence is composed of objects of the same type, the Sequence::from_iter_to_der method can be used
• otherwise, the ToDer trait can be used to create content incrementally

use asn1_rs::{Integer, Sequence, SerializeResult, ToDer};

fn build_seq<'a>() -> SerializeResult<Sequence<'a>> {
    let mut v = Vec::new();
    // add an Integer object (construct type):
    let i = Integer::from_u32(4);
    let _ = i.write_der(&mut v)?;
    // some primitive objects also implement `ToDer`. A string will be mapped as `Utf8String`:
    let _ = "abcd".write_der(&mut v)?;
    // return the sequence built from the DER content
    Ok(Sequence::new(v.into()))
}

let seq = build_seq().unwrap();

Examples

use asn1_rs::{Error, Sequence};

// build sequence
let it = [2, 3, 4].iter();
let seq = Sequence::from_iter_to_der(it).unwrap();

// `seq` now contains the serialized DER representation of the array

// iterate objects
let mut sum = 0;
for item in seq.der_iter::<u32, Error>() {
    // item has type `Result<u32>`, since parsing the serialized bytes could fail
    sum += item.expect("parsing list item failed");
}
assert_eq!(sum, 9);

Note: the above example encodes a SEQUENCE OF INTEGER object, the SequenceOf object could be used to provide a simpler API.

Fields

content: Cow<'a, [u8]>

Serialized DER representation of the sequence content

Implementations

impl<'a> Sequence<'a>

pub const fn new(content: Cow<'a, [u8]>) -> Sequence<'a>

Build a sequence, given the provided content

pub fn into_content(self) -> Cow<'a, [u8]>

Consume the sequence and return the content

pub fn and_then<U, F, E>(self, op: F) -> Result<(&'a [u8], U), Err<E>>

where F: FnOnce(Cow<'a, [u8]>) -> Result<(&'a [u8], U), Err<E>>,

Apply the parsing function to the sequence content, consuming the sequence

Note: this function expects the caller to take ownership of content. In some cases, handling the lifetime of objects is not easy (when keeping only references on data). Other methods are provided (depending on the use case):

• Sequence::parse takes a reference on the sequence data, but does not consume it,
• Sequence::from_der_and_then does the parsing of the sequence and applying the function in one step, ensuring there are only references (and dropping the temporary sequence).

pub fn from_ber_and_then<U, F, E>( bytes: &'a [u8], op: F, ) -> Result<(&'a [u8], U), Err<E>>

where F: FnOnce(&'a [u8]) -> Result<(&'a [u8], U), Err<E>>, E: From<Error>,

Same as Sequence::from_der_and_then, but using BER encoding (no constraints).

pub fn from_der_and_then<U, F, E>( bytes: &'a [u8], op: F, ) -> Result<(&'a [u8], U), Err<E>>

where F: FnOnce(&'a [u8]) -> Result<(&'a [u8], U), Err<E>>, E: From<Error>,

Parse a DER sequence and apply the provided parsing function to content

After parsing, the sequence object and header are discarded.

use asn1_rs::{FromDer, ParseResult, Sequence};

// Parse a SEQUENCE {
//      a INTEGER (0..255),
//      b INTEGER (0..4294967296)
// }
// and return only `(a,b)
fn parser(i: &[u8]) -> ParseResult<(u8, u32)> {
    Sequence::from_der_and_then(i, |i| {
            let (i, a) = u8::from_der(i)?;
            let (i, b) = u32::from_der(i)?;
            Ok((i, (a, b)))
        }
    )
}

pub fn parse<F, T, E>(&'a self, f: F) -> Result<(&'a [u8], T), Err<E>>

where F: FnMut(&'a [u8]) -> Result<(&'a [u8], T), Err<E>>,

Apply the parsing function to the sequence content (non-consuming version)

pub fn parse_into<F, T, E>(self, f: F) -> Result<(&'a [u8], T), Err<E>>

where F: FnMut(&'a [u8]) -> Result<(&'a [u8], T), Err<E>>, E: From<Error>,

Apply the parsing function to the sequence content (consuming version)

Note: to parse and apply a parsing function in one step, use the Sequence::from_der_and_then method.

Limitations

This function fails if the sequence contains Owned data, because the parsing function takes a reference on data (which is dropped).

pub fn ber_iter<T, E>(&'a self) -> SequenceIterator<'a, T, BerParser, E>

where T: FromBer<'a, E>,

Return an iterator over the sequence content, attempting to decode objects as BER

This method can be used when all objects from the sequence have the same type.

pub fn der_iter<T, E>(&'a self) -> SequenceIterator<'a, T, DerParser, E>

where T: FromDer<'a, E>,

Return an iterator over the sequence content, attempting to decode objects as DER

This method can be used when all objects from the sequence have the same type.

pub fn ber_sequence_of<T, E>(&'a self) -> Result<Vec<T>, E>

where T: FromBer<'a, E>, E: From<Error>,

Attempt to parse the sequence as a SEQUENCE OF items (BER), and return the parsed items as a Vec.

pub fn der_sequence_of<T, E>(&'a self) -> Result<Vec<T>, E>

where T: FromDer<'a, E>, E: From<Error>,

Attempt to parse the sequence as a SEQUENCE OF items (DER), and return the parsed items as a Vec.

pub fn into_ber_sequence_of<T, U, E>(self) -> Result<Vec<T>, E>

where T: for<'b> FromBer<'b, E> + ToStatic<Owned = T>, E: From<Error>,

Attempt to parse the sequence as a SEQUENCE OF items (BER) (consuming input), and return the parsed items as a Vec.

Note: if Self is an Owned object, the data will be duplicated (causing allocations) into separate objects.

pub fn into_der_sequence_of<T, U, E>(self) -> Result<Vec<T>, E>

where T: for<'b> FromDer<'b, E> + ToStatic<Owned = T>, E: From<Error>,

Attempt to parse the sequence as a SEQUENCE OF items (DER) (consuming input), and return the parsed items as a Vec.

Note: if Self is an Owned object, the data will be duplicated (causing allocations) into separate objects.

pub fn into_der_sequence_of_ref<T, E>(self) -> Result<Vec<T>, E>

where T: FromDer<'a, E>, E: From<Error>,

impl Sequence<'_>

pub fn from_iter_to_der<T, IT>(it: IT) -> Result<Sequence<'_>, SerializeError>

where IT: Iterator<Item = T>, T: ToDer + Tagged,

Attempt to create a Sequence from an iterator over serializable objects (to DER)

Examples

use asn1_rs::Sequence;

// build sequence
let it = [2, 3, 4].iter();
let seq = Sequence::from_iter_to_der(it).unwrap();

Trait Implementations

impl AsRef<[u8]> for Sequence<'_>

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl CheckDerConstraints for Sequence<'_>

fn check_constraints(_any: &Any<'_>) -> Result<(), Error>

impl<'a> Clone for Sequence<'a>

fn clone(&self) -> Sequence<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for Sequence<'a>

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

Formats the value using the given formatter.

impl<'a> PartialEq for Sequence<'a>

fn eq(&self, other: &Sequence<'a>) -> 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 Tagged for Sequence<'_>

const TAG: Tag = Tag::Sequence

impl ToDer for Sequence<'_>

fn to_der_len(&self) -> Result<usize, Error>

Get the length of the object (including the header), when encoded

fn write_der_header( &self, writer: &mut dyn Write, ) -> Result<usize, SerializeError>

Attempt to write the DER header to this writer.

fn write_der_content( &self, writer: &mut dyn Write, ) -> Result<usize, SerializeError>

Attempt to write the DER content (all except header) to this writer.

fn to_der_vec(&self) -> Result<Vec<u8>, SerializeError>

Write the DER encoded representation to a newly allocated Vec<u8>.

fn to_der_vec_raw(&self) -> Result<Vec<u8>, SerializeError>

Similar to using to_vec, but uses provided values without changes. This can generate an invalid encoding for a DER object.

fn write_der(&self, writer: &mut dyn Write) -> Result<usize, SerializeError>

Attempt to write the DER encoded representation (header and content) into this writer.

fn write_der_raw(&self, writer: &mut dyn Write) -> Result<usize, SerializeError>

Similar to using to_der, but uses provided values without changes. This can generate an invalid encoding for a DER object.

impl ToStatic for Sequence<'_>

type Owned = Sequence<'static>

fn to_static(&self) -> <Sequence<'_> as ToStatic>::Owned

impl<'a, 'b> TryFrom<&'b Any<'a>> for Sequence<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(any: &'b Any<'a>) -> Result<Sequence<'a>, Error>

Performs the conversion.

impl<'a> TryFrom<Any<'a>> for Sequence<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(any: Any<'a>) -> Result<Sequence<'a>, Error>

Performs the conversion.

impl DerAutoDerive for Sequence<'_>

impl<'a> Eq for Sequence<'a>

impl<'a> StructuralPartialEq for Sequence<'a>