Struct Class for TLS 1.3

Overview

The Struct class extends the Uint8Array to represent a structured collection of data as defined in the TLS 1.3 specification. It provides a way to create, manipulate, and manage arrays of Uint8Array or numbers while ensuring proper type validation and concatenation of values.

Features

• Flexible Construction: Create a Struct instance with an array of Uint8Array or numbers.
• Automatic Concatenation: When initialized, values are automatically concatenated into a single Uint8Array.
• Member Access: Access the individual components of the Struct via the items property.
• Static Factory Method: Use Struct.createFrom or Struct.newStruct to create instances.

Usage

Creating a Struct

You can create a Struct instance with either Uint8Array instances or numbers:

import { Struct } from './struct.js';

// Using the constructor directly
const struct1 = new Struct(new Uint8Array([1, 2]), new Uint8Array([3]));
const struct2 = new Struct(1, 2, 3); // Converts numbers to Uint8Array

console.log(struct1); // Uint8Array(5) [ 1, 2, 3 ]
console.log(struct2.items); // [ Uint8Array(1) [ 1 ], Uint8Array(1) [ 2 ], Uint8Array(1) [ 3 ] ]

Using Static Methods

You can also create a Struct instance using the static methods:

const struct3 = Struct.createFrom(new Uint8Array([4, 5]), 6);
const struct4 = Struct.newStruct(7, 8, new Uint8Array([9]));

console.log(struct3.items); // [ Uint8Array(1) [ 4 ], Uint8Array(1) [ 5 ], Uint8Array(1) [ 6 ] ]
console.log(struct4.items); // [ Uint8Array(1) [ 7 ], Uint8Array(1) [ 8 ], Uint8Array(1) [ 9 ] ]

Default Initialization

If no arguments are passed during initialization, a default value of 1 is assigned:

const defaultStruct = new Struct();
console.log(defaultStruct.items); // [ Uint8Array(0) [ 0 ] ]

Constrained Class

The Constrained class extends the Uint8Array to represent an array with specified minimum and maximum length constraints. It ensures that the data adheres to these constraints during initialization.

Features

• Length Constraints: Specify minimum and maximum lengths for the data.
• Type Validation: Automatically validates that the provided items are either Uint8Array or numbers.

Usage

You can create a Constrained instance as follows:

import { Constrained } from './constrained.js';

class TestConstrained extends Constrained {}

const constrained = new TestConstrained(2, 5, new Uint8Array([1, 2]), 3);
console.log(constrained.items); // [ Uint8Array(1) [ 1, 2 ], Uint8Array(1) [ 3 ] ]

Error Handling

The constructor will throw errors if the constraints are violated:

try {
    const invalidConstrained = new TestConstrained(-1, 5);
} catch (e) {
    console.error(e); // RangeError: MIN length cannot be negative.
}

Utility Functions

The utils.js file contains several utility functions that assist with the manipulation and validation of Uint8Array data.

Functions

• ensureUint8Array(...items): Validates that all provided items are Uint8Array instances or converts them from numbers.

  import { ensureUint8Array } from './utils.js';
  
  const result = ensureUint8Array(new Uint8Array([1, 2]), 3);

• concatOctet(...arrays): Concatenates multiple Uint8Array instances into a single Uint8Array.

  import { concatOctet } from './utils.js';
  
  const concatenated = concatOctet(new Uint8Array([1]), new Uint8Array([2, 3]));

• uint8ArrayToValue(uint8array): Converts a Uint8Array to a numeric value.

  import { uint8ArrayToValue } from './utils.js';
  
  const value = uint8ArrayToValue(new Uint8Array([0, 0, 1, 0])); // 256

Type Definitions

The type definitions for the Struct, Constrained, and utility functions can be found in the accompanying .d.ts files.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributions

Contributions are welcome! Please feel free to submit a pull request or open an issue to discuss changes.

Donation

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