smart-buffer

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

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

• Old constructor patterns have been completely removed. It's now required to use the SmartBuffer.fromXXX() factory constructors.
• rewind(), skip(), moveTo() have been removed. (see offsets)
• Internal private properties are now prefixed with underscores (_)
• All writeXXX() methods that are given an offset will now overwrite data instead of insert. (see write vs insert)
• insertXXX() methods have been added for when you want to insert data at a specific offset (this replaces the old behavior of writeXXX() when an offset was provided)

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

1// Javascript
2const SmartBuffer = require('smart-buffer').SmartBuffer;
3
4// Typescript
5import { 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.

1function createLoginPacket(username, password, age, country) {
2    const packet = new SmartBuffer();
3    packet.writeUInt16LE(0x0060); // Some packet type
4    packet.writeStringNT(username);
5    packet.writeStringNT(password);
6    packet.writeUInt8(age);
7    packet.writeStringNT(country);
8    packet.insertUInt16LE(packet.length - 2, 2);
9
10    return packet.toBuffer();
11}

With the above function, you now can do this:

1const login = createLoginPacket("Josh", "secret123", 22, "United States");
2
3// <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:

1
2const reader = SmartBuffer.fromBuffer(login);
3
4const logininfo = {
5    packetType: reader.readUInt16LE(),
6    packetLength: reader.readUInt16LE(),
7    username: reader.readStringNT(),
8    password: reader.readStringNT(),
9    age: reader.readUInt8(),
10    country: reader.readStringNT()
11};
12
13/*
14{
15    packetType: 96, (0x0060)
16    packetLength: 30,
17    username: 'Josh',
18    password: 'secret123',
19    age: 22,
20    country: 'United States'
21}
22*/

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:

1const buff = SmartBuffer.fromBuffer(new Buffer([1,2,3,4,5,6]));
2buff.writeInt8(7, 2);
3console.log(buff.toBuffer())
4
5// <Buffer 01 02 07 03 04 05 06>

SmartBuffer v4:

1const buff = SmartBuffer.fromBuffer(new Buffer([1,2,3,4,5,6]));
2buff.writeInt8(7, 2);
3console.log(buff.toBuffer());
4
5// <Buffer 01 02 07 04 05 06>

To insert you instead should use:

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

1// Creating SmartBuffer from existing Buffer
2const buff = SmartBuffer.fromBuffer(buffer); // Creates instance from buffer. (Uses default utf8 encoding)
3const buff = SmartBuffer.fromBuffer(buffer, 'ascii'); // Creates instance from buffer with ascii encoding for strings.
4
5// Creating SmartBuffer with specified internal Buffer size. (Note: this is not a hard cap, the internal buffer will grow as needed).
6const buff = SmartBuffer.fromSize(1024); // Creates instance with internal Buffer size of 1024.
7const buff = SmartBuffer.fromSize(1024, 'utf8'); // Creates instance with internal Buffer size of 1024, and utf8 encoding for strings.
8
9// Creating SmartBuffer with options object. This one specifies size and encoding.
10const buff = SmartBuffer.fromOptions({
11    size: 1024,
12    encoding: 'ascii'
13});
14
15// Creating SmartBuffer with options object. This one specified an existing Buffer.
16const buff = SmartBuffer.fromOptions({
17    buff: buffer
18});
19
20// Creating SmartBuffer from a string.
21const buff = SmartBuffer.fromBuffer(Buffer.from('some string', 'utf8'));
22
23// Just want a regular SmartBuffer with all default options?
24const 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])

• options {SmartBufferOptions} An optional options object to construct a SmartBuffer with.

Examples:

1const buff = new SmartBuffer();
2const buff = new SmartBuffer({
3    size: 1024,
4    encoding: 'ascii'
5});

Class Method: fromBuffer(buffer[, encoding])

• buffer {Buffer} The Buffer instance to wrap.
• encoding {string} The string encoding to use. Default: 'utf8'

Examples:

1const someBuffer = Buffer.from('some string');
2const buff = SmartBuffer.fromBuffer(someBuffer); // Defaults to utf8
3const buff = SmartBuffer.fromBuffer(someBuffer, 'ascii');

Class Method: fromSize(size[, encoding])

• size {number} The size to initialize the internal Buffer.
• encoding {string} The string encoding to use. Default: 'utf8'

Examples:

1const buff = SmartBuffer.fromSize(1024); // Defaults to utf8
2const buff = SmartBuffer.fromSize(1024, 'ascii');

Class Method: fromOptions(options)

• options {SmartBufferOptions} The Buffer instance to wrap.

1interface SmartBufferOptions {
2    encoding?: BufferEncoding; // Defaults to utf8
3    size?: number; // Defaults to 4096
4    buff?: Buffer;
5}

Examples:

1const buff = SmartBuffer.fromOptions({
2    size: 1024
3};
4const buff = SmartBuffer.fromOptions({
5    size: 1024,
6    encoding: 'utf8'
7});
8const buff = SmartBuffer.fromOptions({
9    encoding: 'utf8'
10});
11
12const someBuff = Buffer.from('some string', 'utf8');
13const buff = SmartBuffer.fromOptions({
14    buffer: someBuff,
15    encoding: 'utf8'
16});

Integers

buff.readInt8([offset])

buff.readUInt8([offset])

• offset {number} Optional position to start reading data from. Default: Auto managed offset
• Returns {number}

Read a Int8 value.

buff.readInt16BE([offset])

buff.readInt16LE([offset])

buff.readUInt16BE([offset])

buff.readUInt16LE([offset])

• offset {number} Optional position to start reading data from. Default: Auto managed offset
• Returns {number}

Read a 16 bit integer value.

buff.readInt32BE([offset])

buff.readInt32LE([offset])

buff.readUInt32BE([offset])

buff.readUInt32LE([offset])

• offset {number} Optional position to start reading data from. Default: Auto managed offset
• Returns {number}

Read a 32 bit integer value.

buff.writeInt8(value[, offset])

buff.writeUInt8(value[, offset])

• value {number} The value to write.
• offset {number} An optional offset to write this value to. Default: Auto managed offset
• Returns {this}

Write a Int8 value.

buff.insertInt8(value, offset)

buff.insertUInt8(value, offset)

• value {number} The value to insert.
• offset {number} The offset to insert this data at.
• Returns {this}

Insert a Int8 value.

buff.writeInt16BE(value[, offset])

buff.writeInt16LE(value[, offset])

buff.writeUInt16BE(value[, offset])

buff.writeUInt16LE(value[, offset])

• value {number} The value to write.
• offset {number} An optional offset to write this value to. Default: Auto managed offset
• Returns {this}

Write a 16 bit integer value.

buff.insertInt16BE(value, offset)

buff.insertInt16LE(value, offset)

buff.insertUInt16BE(value, offset)

buff.insertUInt16LE(value, offset)

• value {number} The value to insert.
• offset {number} The offset to insert this data at.
• Returns {this}

Insert a 16 bit integer value.

buff.writeInt32BE(value[, offset])

buff.writeInt32LE(value[, offset])

buff.writeUInt32BE(value[, offset])

buff.writeUInt32LE(value[, offset])

• value {number} The value to write.
• offset {number} An optional offset to write this value to. Default: Auto managed offset
• Returns {this}

Write a 32 bit integer value.

buff.insertInt32BE(value, offset)

buff.insertInt32LE(value, offset)

buff.insertUInt32BE(value, offset)

buff.nsertUInt32LE(value, offset)

• value {number} The value to insert.
• offset {number} The offset to insert this data at.
• Returns {this}

Insert a 32 bit integer value.

Floating Point Numbers

buff.readFloatBE([offset])

buff.readFloatLE([offset])

• offset {number} Optional position to start reading data from. Default: Auto managed offset
• Returns {number}

Read a Float value.

buff.readDoubleBE([offset])

buff.readDoubleLE([offset])

• offset {number} Optional position to start reading data from. Default: Auto managed offset
• Returns {number}

Read a Double value.

buff.writeFloatBE(value[, offset])

buff.writeFloatLE(value[, offset])

• value {number} The value to write.
• offset {number} An optional offset to write this value to. Default: Auto managed offset
• Returns {this}

Write a Float value.

buff.insertFloatBE(value, offset)

buff.insertFloatLE(value, offset)

• value {number} The value to insert.
• offset {number} The offset to insert this data at.
• Returns {this}

Insert a Float value.

buff.writeDoubleBE(value[, offset])

buff.writeDoubleLE(value[, offset])

• value {number} The value to write.
• offset {number} An optional offset to write this value to. Default: Auto managed offset
• Returns {this}

Write a Double value.

buff.insertDoubleBE(value, offset)

buff.insertDoubleLE(value, offset)

• value {number} The value to insert.
• offset {number} The offset to insert this data at.
• Returns {this}

Insert a Double value.

Strings

buff.readString()

buff.readString(size[, encoding])

buff.readString(encoding)

• size {number} The number of bytes to read. Default: Reads to the end of the Buffer.
• encoding {string} The string encoding to use. Default: utf8.

Read a string value.

Examples:

1const buff = SmartBuffer.fromBuffer(Buffer.from('hello there', 'utf8'));
2buff.readString(); // 'hello there'
3buff.readString(2); // 'he'
4buff.readString(2, 'utf8'); // 'he'
5buff.readString('utf8'); // 'hello there'

buff.writeString(value)

buff.writeString(value[, offset])

buff.writeString(value[, encoding])

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

• value {string} The string value to write.
• offset {number} The offset to write this value to. Default: Auto managed offset
• encoding {string} An optional string encoding to use. Default: utf8

Write a string value.

Examples:

1buff.writeString('hello'); // Auto managed offset
2buff.writeString('hello', 2);
3buff.writeString('hello', 'utf8') // Auto managed offset
4buff.writeString('hello', 2, 'utf8');

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

• value {string} The string value to write.
• offset {number} The offset to write this value to.
• encoding {string} An optional string encoding to use. Default: utf8

Insert a string value.

Examples:

1buff.insertString('hello', 2);
2buff.insertString('hello', 2, 'utf8');

Null Terminated Strings

buff.readStringNT()

buff.readStringNT(encoding)

• encoding {string} The string encoding to use. Default: utf8.

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

Examples:

1const buff = SmartBuffer.fromBuffer(Buffer.from('hello\0 there', 'utf8'));
2buff.readStringNT(); // 'hello'
3
4// If we called this again:
5buff.readStringNT(); // ' there'

buff.writeStringNT(value)

buff.writeStringNT(value[, offset])

buff.writeStringNT(value[, encoding])

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

• value {string} The string value to write.
• offset {number} The offset to write this value to. Default: Auto managed offset
• encoding {string} An optional string encoding to use. Default: utf8

Write a null terminated string value.

Examples:

1buff.writeStringNT('hello'); // Auto managed offset   <Buffer 68 65 6c 6c 6f 00>
2buff.writeStringNT('hello', 2); // <Buffer 00 00 68 65 6c 6c 6f 00>
3buff.writeStringNT('hello', 'utf8') // Auto managed offset
4buff.writeStringNT('hello', 2, 'utf8');

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

• value {string} The string value to write.
• offset {number} The offset to write this value to.
• encoding {string} An optional string encoding to use. Default: utf8

Insert a null terminated string value.

Examples:

1buff.insertStringNT('hello', 2);
2buff.insertStringNT('hello', 2, 'utf8');

Buffers

buff.readBuffer([length])

• length {number} The number of bytes to read into a Buffer. Default: Reads to the end of the Buffer

Read a Buffer of a specified size.

buff.writeBuffer(value[, offset])

• value {Buffer} The buffer value to write.
• offset {number} An optional offset to write the value to. Default: Auto managed offset

buff.insertBuffer(value, offset)

• value {Buffer} The buffer value to write.
• offset {number} The offset to write the value to.

buff.readBufferNT()

Read a null terminated Buffer.

buff.writeBufferNT(value[, offset])

• value {Buffer} The buffer value to write.
• offset {number} An optional offset to write the value to. Default: Auto managed offset

Write a null terminated Buffer.

buff.insertBufferNT(value, offset)

• value {Buffer} The buffer value to write.
• offset {number} The offset to write the value to.

Insert a null terminated Buffer.

Offsets

buff.readOffset

buff.readOffset(offset)

• offset {number} The new read offset value to set.
• Returns: The current read offset

Gets or sets the current read offset.

Examples:

1const currentOffset = buff.readOffset; // 5
2
3buff.readOffset = 10;
4
5console.log(buff.readOffset) // 10

buff.writeOffset

buff.writeOffset(offset)

• offset {number} The new write offset value to set.
• Returns: The current write offset

Gets or sets the current write offset.

Examples:

1const currentOffset = buff.writeOffset; // 5
2
3buff.writeOffset = 10;
4
5console.log(buff.writeOffset) // 10

buff.encoding

buff.encoding(encoding)

• encoding {string} The new string encoding to set.
• Returns: The current string encoding

Gets or sets the current string encoding.

Examples:

1const currentEncoding = buff.encoding; // 'utf8'
2
3buff.encoding = 'ascii';
4
5console.log(buff.encoding) // 'ascii'

Other

buff.clear()

Clear and resets the SmartBuffer instance.

buff.remaining()

• Returns Remaining data left to be read

Gets the number of remaining bytes to be read.

buff.internalBuffer

• Returns: {Buffer}

Gets the internally managed Buffer (Includes unmanaged data).

Examples:

1const buff = SmartBuffer.fromSize(16);
2buff.writeString('hello');
3console.log(buff.InternalBuffer); // <Buffer 68 65 6c 6c 6f 00 00 00 00 00 00 00 00 00 00 00>

buff.toBuffer()

• Returns: {Buffer}

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

Examples:

1const buff = SmartBuffer.fromSize(16);
2buff.writeString('hello');
3console.log(buff.toBuffer()); // <Buffer 68 65 6c 6c 6f>

buff.toString([encoding])

• encoding {string} The string encoding to use when converting to a string. Default: utf8
• Returns {string}

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.