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import * as pvtsutils from "pvtsutils";
import * as pvutils from "pvutils";
import { IBerConvertible } from "../types";
import { EMPTY_BUFFER } from "./constants";
import { LocalBaseBlock, LocalBaseBlockJson } from "./LocalBaseBlock";
import { checkBufferParams } from "./utils";
export interface ILocalLengthBlock {
isIndefiniteForm: boolean;
longFormUsed: boolean;
length: number;
}
export interface LocalLengthBlockParams {
lenBlock?: Partial<ILocalLengthBlock>;
}
export interface LocalLengthBlockJson extends LocalBaseBlockJson, ILocalLengthBlock {
isIndefiniteForm: boolean;
longFormUsed: boolean;
length: number;
}
export class LocalLengthBlock extends LocalBaseBlock implements ILocalLengthBlock, IBerConvertible {
public static override NAME = "lengthBlock";
public isIndefiniteForm: boolean;
public longFormUsed: boolean;
public length: number;
constructor({
lenBlock = {},
}: LocalLengthBlockParams = {}) {
super();
this.isIndefiniteForm = lenBlock.isIndefiniteForm ?? false;
this.longFormUsed = lenBlock.longFormUsed ?? false;
this.length = lenBlock.length ?? 0;
}
public fromBER(inputBuffer: ArrayBuffer | Uint8Array, inputOffset: number, inputLength: number): number {
const view = pvtsutils.BufferSourceConverter.toUint8Array(inputBuffer);
// Basic check for parameters
if (!checkBufferParams(this, view, inputOffset, inputLength)) {
return -1;
}
//#region Getting Uint8Array from ArrayBuffer
const intBuffer = view.subarray(inputOffset, inputOffset + inputLength);
//#endregion
//#region Initial checks
if (intBuffer.length === 0) {
this.error = "Zero buffer length";
return -1;
}
if (intBuffer[0] === 0xFF) {
this.error = "Length block 0xFF is reserved by standard";
return -1;
}
//#endregion
//#region Check for length form type
this.isIndefiniteForm = intBuffer[0] === 0x80;
//#endregion
//#region Stop working in case of indefinite length form
if (this.isIndefiniteForm) {
this.blockLength = 1;
return (inputOffset + this.blockLength);
}
//#endregion
//#region Check is long form of length encoding using
this.longFormUsed = !!(intBuffer[0] & 0x80);
//#endregion
//#region Stop working in case of short form of length value
if (this.longFormUsed === false) {
this.length = (intBuffer[0]);
this.blockLength = 1;
return (inputOffset + this.blockLength);
}
//#endregion
//#region Calculate length value in case of long form
const count = intBuffer[0] & 0x7F;
if (count > 8) // Too big length value
{
this.error = "Too big integer";
return -1;
}
if ((count + 1) > intBuffer.length) {
this.error = "End of input reached before message was fully decoded";
return -1;
}
const lenOffset = inputOffset + 1;
const lengthBufferView = view.subarray(lenOffset, lenOffset + count);
if (lengthBufferView[count - 1] === 0x00)
this.warnings.push("Needlessly long encoded length");
this.length = pvutils.utilFromBase(lengthBufferView, 8);
if (this.longFormUsed && (this.length <= 127))
this.warnings.push("Unnecessary usage of long length form");
this.blockLength = count + 1;
//#endregion
return (inputOffset + this.blockLength); // Return current offset in input buffer
}
public toBER(sizeOnly = false): ArrayBuffer {
//#region Initial variables
let retBuf: ArrayBuffer;
let retView: Uint8Array;
//#endregion
if (this.length > 127)
this.longFormUsed = true;
if (this.isIndefiniteForm) {
retBuf = new ArrayBuffer(1);
if (sizeOnly === false) {
retView = new Uint8Array(retBuf);
retView[0] = 0x80;
}
return retBuf;
}
if (this.longFormUsed) {
const encodedBuf = pvutils.utilToBase(this.length, 8);
if (encodedBuf.byteLength > 127) {
this.error = "Too big length";
return (EMPTY_BUFFER);
}
retBuf = new ArrayBuffer(encodedBuf.byteLength + 1);
if (sizeOnly)
return retBuf;
const encodedView = new Uint8Array(encodedBuf);
retView = new Uint8Array(retBuf);
retView[0] = encodedBuf.byteLength | 0x80;
for (let i = 0; i < encodedBuf.byteLength; i++)
retView[i + 1] = encodedView[i];
return retBuf;
}
retBuf = new ArrayBuffer(1);
if (sizeOnly === false) {
retView = new Uint8Array(retBuf);
retView[0] = this.length;
}
return retBuf;
}
public override toJSON(): LocalLengthBlockJson {
return {
...super.toJSON(),
isIndefiniteForm: this.isIndefiniteForm,
longFormUsed: this.longFormUsed,
length: this.length,
};
}
}