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smart-buffer Build Status Coverage Status

smart-buffer is a Buffer wrapper that adds automatic read & write offset tracking, string operations, data insertions, and more.

stats

Key Features: * Proxies all of the Buffer write and read functions * Keeps track of read and write offsets automatically * Grows the internal Buffer as needed * Useful string operations. (Null terminating strings) * Allows for inserting values at specific points in the Buffer * Built in TypeScript * Type Definitions Provided * Browser Support (using Webpack/Browserify) * Full test coverage

Requirements: * Node v4.0+ is supported at this time. (Versions prior to 2.0 will work on node 0.10)

Breaking Changes in v4.0

Looking for v3 docs?

Legacy documentation for version 3 and prior can be found here.

Installing:

yarn add smart-buffer

or

npm install smart-buffer

Note: The published NPM package includes the built javascript library. If you cloned this repo and wish to build the library manually use:

npm run build

Using smart-buffer

// Javascript
const SmartBuffer = require('smart-buffer').SmartBuffer;

// Typescript
import { SmartBuffer, SmartBufferOptions} from 'smart-buffer';

Simple Example

Building a packet that uses the following protocol specification:

[PacketType:2][PacketLength:2][Data:XX]

To build this packet using the vanilla Buffer class, you would have to count up the length of the data payload beforehand. You would also need to keep track of the current “cursor” position in your Buffer so you write everything in the right places. With smart-buffer you don’t have to do either of those things.

function createLoginPacket(username, password, age, country) {
    const packet = new SmartBuffer();
    packet.writeUInt16LE(0x0060); // Some packet type
    packet.writeStringNT(username);
    packet.writeStringNT(password);
    packet.writeUInt8(age);
    packet.writeStringNT(country);
    packet.insertUInt16LE(packet.length - 2, 2);

    return packet.toBuffer();
}

With the above function, you now can do this:

const login = createLoginPacket("Josh", "secret123", 22, "United States");

// <Buffer 60 00 1e 00 4a 6f 73 68 00 73 65 63 72 65 74 31 32 33 00 16 55 6e 69 74 65 64 20 53 74 61 74 65 73 00>

Notice that the [PacketLength:2] value (1e 00) was inserted at position 2.

Reading back the packet we created above is just as easy:


const reader = SmartBuffer.fromBuffer(login);

const logininfo = {
    packetType: reader.readUInt16LE(),
    packetLength: reader.readUInt16LE(),
    username: reader.readStringNT(),
    password: reader.readStringNT(),
    age: reader.readUInt8(),
    country: reader.readStringNT()
};

/*
{
    packetType: 96, (0x0060)
    packetLength: 30,
    username: 'Josh',
    password: 'secret123',
    age: 22,
    country: 'United States'
}
*/

Write vs Insert

In prior versions of SmartBuffer, .writeXXX(value, offset) calls would insert data when an offset was provided. In version 4, this will now overwrite the data at the offset position. To insert data there are now corresponding .insertXXX(value, offset) methods.

SmartBuffer v3:

const buff = SmartBuffer.fromBuffer(new Buffer([1,2,3,4,5,6]));
buff.writeInt8(7, 2);
console.log(buff.toBuffer())

// <Buffer 01 02 07 03 04 05 06>

SmartBuffer v4:

const buff = SmartBuffer.fromBuffer(new Buffer([1,2,3,4,5,6]));
buff.writeInt8(7, 2);
console.log(buff.toBuffer());

// <Buffer 01 02 07 04 05 06>

To insert you instead should use:

const buff = SmartBuffer.fromBuffer(new Buffer([1,2,3,4,5,6]));
buff.insertInt8(7, 2);
console.log(buff.toBuffer());

// <Buffer 01 02 07 03 04 05 06>

Note: Insert/Writing to a position beyond the currently tracked internal Buffer will zero pad to your offset.

Constructing a smart-buffer

There are a few different ways to construct a SmartBuffer instance.

// Creating SmartBuffer from existing Buffer
const buff = SmartBuffer.fromBuffer(buffer); // Creates instance from buffer. (Uses default utf8 encoding)
const buff = SmartBuffer.fromBuffer(buffer, 'ascii'); // Creates instance from buffer with ascii encoding for strings.

// Creating SmartBuffer with specified internal Buffer size. (Note: this is not a hard cap, the internal buffer will grow as needed).
const buff = SmartBuffer.fromSize(1024); // Creates instance with internal Buffer size of 1024.
const buff = SmartBuffer.fromSize(1024, 'utf8'); // Creates instance with internal Buffer size of 1024, and utf8 encoding for strings.

// Creating SmartBuffer with options object. This one specifies size and encoding.
const buff = SmartBuffer.fromOptions({
    size: 1024,
    encoding: 'ascii'
});

// Creating SmartBuffer with options object. This one specified an existing Buffer.
const buff = SmartBuffer.fromOptions({
    buff: buffer
});

// Creating SmartBuffer from a string.
const buff = SmartBuffer.fromBuffer(Buffer.from('some string', 'utf8'));

// Just want a regular SmartBuffer with all default options?
const buff = new SmartBuffer();

Api Reference:

Note: SmartBuffer is fully documented with Typescript definitions as well as jsdocs so your favorite editor/IDE will have intellisense.

Table of Contents

  1. Constructing
  2. Numbers
    1. Integers
    2. Floating Points
  3. Strings
    1. Strings
    2. Null Terminated Strings
  4. Buffers
  5. Offsets
  6. Other

Constructing

constructor()

constructor([options])

Examples:

const buff = new SmartBuffer();
const buff = new SmartBuffer({
    size: 1024,
    encoding: 'ascii'
});

Class Method: fromBuffer(buffer[, encoding])

Examples:

const someBuffer = Buffer.from('some string');
const buff = SmartBuffer.fromBuffer(someBuffer); // Defaults to utf8
const buff = SmartBuffer.fromBuffer(someBuffer, 'ascii');

Class Method: fromSize(size[, encoding])

Examples:

const buff = SmartBuffer.fromSize(1024); // Defaults to utf8
const buff = SmartBuffer.fromSize(1024, 'ascii');

Class Method: fromOptions(options)

interface SmartBufferOptions {
    encoding?: BufferEncoding; // Defaults to utf8
    size?: number; // Defaults to 4096
    buff?: Buffer;
}

Examples:

const buff = SmartBuffer.fromOptions({
    size: 1024
};
const buff = SmartBuffer.fromOptions({
    size: 1024,
    encoding: 'utf8'
});
const buff = SmartBuffer.fromOptions({
    encoding: 'utf8'
});

const someBuff = Buffer.from('some string', 'utf8');
const buff = SmartBuffer.fromOptions({
    buffer: someBuff,
    encoding: 'utf8'
});

Integers

readInt8([offset])

Read a Int8 value.

buff.readInt16BE([offset])

buff.readInt16LE([offset])

buff.readUInt16BE([offset])

buff.readUInt16LE([offset])

Read a 16 bit integer value.

buff.readInt32BE([offset])

buff.readInt32LE([offset])

buff.readUInt32BE([offset])

buff.readUInt32LE([offset])

Read a 32 bit integer value.

buff.writeInt8(value[, offset])

buff.writeUInt8(value[, offset])

Write a Int8 value.

buff.insertInt8(value, offset)

buff.insertUInt8(value, offset)

Insert a Int8 value.

buff.writeInt16BE(value[, offset])

buff.writeInt16LE(value[, offset])

buff.writeUInt16BE(value[, offset])

buff.writeUInt16LE(value[, offset])

Write a 16 bit integer value.

buff.insertInt16BE(value, offset)

buff.insertInt16LE(value, offset)

buff.insertUInt16BE(value, offset)

buff.insertUInt16LE(value, offset)

Insert a 16 bit integer value.

buff.writeInt32BE(value[, offset])

buff.writeInt32LE(value[, offset])

buff.writeUInt32BE(value[, offset])

buff.writeUInt32LE(value[, offset])

Write a 32 bit integer value.

buff.insertInt32BE(value, offset)

buff.insertInt32LE(value, offset)

buff.insertUInt32BE(value, offset)

buff.nsertUInt32LE(value, offset)

Insert a 32 bit integer value.

Floating Point Numbers

buff.readFloatBE([offset])

buff.readFloatLE([offset])

Read a Float value.

buff.eadDoubleBE([offset])

buff.readDoubleLE([offset])

Read a Double value.

buff.writeFloatBE(value[, offset])

buff.writeFloatLE(value[, offset])

Write a Float value.

buff.insertFloatBE(value, offset)

buff.insertFloatLE(value, offset)

Insert a Float value.

buff.writeDoubleBE(value[, offset])

buff.writeDoubleLE(value[, offset])

Write a Double value.

buff.insertDoubleBE(value, offset)

buff.insertDoubleLE(value, offset)

Insert a Double value.

Strings

buff.readString()

buff.readString(size[, encoding])

buff.readString(encoding)

Read a string value.

Examples:

const buff = SmartBuffer.fromBuffer(Buffer.from('hello there', 'utf8'));
buff.readString(); // 'hello there'
buff.readString(2); // 'he'
buff.readString(2, 'utf8'); // 'he'
buff.readString('utf8'); // 'hello there'

buff.writeString(value)

buff.writeString(value[, offset])

buff.writeString(value[, encoding])

buff.writeString(value[, offset[, encoding]])

Write a string value.

Examples:

buff.writeString('hello'); // Auto managed offset
buff.writeString('hello', 2);
buff.writeString('hello', 'utf8') // Auto managed offset
buff.writeString('hello', 2, 'utf8');

buff.insertString(value, offset[, encoding])

Insert a string value.

Examples:

buff.insertString('hello', 2);
buff.insertString('hello', 2, 'utf8');

Null Terminated Strings

buff.readStringNT()

buff.readStringNT(encoding)

Read a null terminated string value. (If a null is not found, it will read to the end of the Buffer).

Examples:

const buff = SmartBuffer.fromBuffer(Buffer.from('hello\0 there', 'utf8'));
buff.readStringNT(); // 'hello'

// If we called this again:
buff.readStringNT(); // ' there'

buff.writeStringNT(value)

buff.writeStringNT(value[, offset])

buff.writeStringNT(value[, encoding])

buff.writeStringNT(value[, offset[, encoding]])

Write a null terminated string value.

Examples:

buff.writeStringNT('hello'); // Auto managed offset   <Buffer 68 65 6c 6c 6f 00>
buff.writeStringNT('hello', 2); // <Buffer 00 00 68 65 6c 6c 6f 00>
buff.writeStringNT('hello', 'utf8') // Auto managed offset
buff.writeStringNT('hello', 2, 'utf8');

buff.insertStringNT(value, offset[, encoding])

Insert a null terminated string value.

Examples:

buff.insertStringNT('hello', 2);
buff.insertStringNT('hello', 2, 'utf8');

Buffers

buff.readBuffer([length])

Read a Buffer of a specified size.

buff.writeBuffer(value[, offset])

buff.insertBuffer(value, offset)

buff.readBufferNT()

Read a null terminated Buffer.

buff.writeBufferNT(value[, offset])

Write a null terminated Buffer.

buff.insertBufferNT(value, offset)

Insert a null terminated Buffer.

Offsets

buff.readOffset

buff.readOffset(offset)

Gets or sets the current read offset.

Examples:

const currentOffset = buff.readOffset; // 5

buff.readOffset = 10;

console.log(buff.readOffset) // 10

buff.writeOffset

buff.writeOffset(offset)

Gets or sets the current write offset.

Examples:

const currentOffset = buff.writeOffset; // 5

buff.writeOffset = 10;

console.log(buff.writeOffset) // 10

buff.encoding

buff.encoding(encoding)

Gets or sets the current string encoding.

Examples:

const currentEncoding = buff.encoding; // 'utf8'

buff.encoding = 'ascii';

console.log(buff.encoding) // 'ascii'

Other

buff.clear()

Clear and resets the SmartBuffer instance.

buff.remaining()

Gets the number of remaining bytes to be read.

buff.internalBuffer

Gets the internally managed Buffer (Includes unmanaged data).

Examples:

const buff = SmartBuffer.fromSize(16);
buff.writeString('hello');
console.log(buff.InternalBuffer); // <Buffer 68 65 6c 6c 6f 00 00 00 00 00 00 00 00 00 00 00>

buff.toBuffer()

Gets a sliced Buffer instance of the internally managed Buffer. (Only includes managed data)

Examples:

const buff = SmartBuffer.fromSize(16);
buff.writeString('hello');
console.log(buff.toBuffer()); // <Buffer 68 65 6c 6c 6f>

buff.toString([encoding])

Gets a string representation of all data in the SmartBuffer.

buff.destroy()

Destroys the SmartBuffer instance.

License

This work is licensed under the MIT license.