Method Write

p2p/encrypt.go:127–169

Write() writes the data bytes to the encrypted connection

(data []byte)

// Write() writes the data bytes to the encrypted connection
func (c *EncryptedConn) Write(data []byte) (n int, err error) {
	// fallback to regular conn in case encrypted conn is not yet set
	if c.send.aead == nil {
		return c.conn.Write(data)
	}
	// thread safety sends
	c.send.Lock()
	defer c.send.Unlock()
	// setup data variables
	chunkSize, chunk := 0, []byte(nil)
	// loop until no more data to send
	for dataSize := len(data); dataSize > 0; dataSize = len(data) {
		// a 'buffer pool' saves resources by re-using buffers, take 2 buffers from the pool
		cipherTextBuffer, plainTextBuffer := pool.Get(crypto.EncryptedFrameSize), pool.Get(crypto.FrameSize)
		// if total data to write can be fit into a single chunk
		if dataSize < crypto.MaxDataSize {
			chunk = data
			data = nil
		} else { // else load the next chunk and save the rest of the data
			chunk = data[:crypto.MaxDataSize]
			data = data[crypto.MaxDataSize:]
		}
		chunkSize = len(chunk)
		// size of data is the first 4 bytes of the message
		binary.LittleEndian.PutUint32(plainTextBuffer, uint32(chunkSize))
		// the actual chunk comes after the first 4 bytes
		copy(plainTextBuffer[crypto.LengthHeaderSize:], chunk)
		// encrypt the plain text into the cipher buffer
		c.send.aead.Seal(cipherTextBuffer[:0], c.send.nonce[:], plainTextBuffer, nil)
		// increment the 'write state' nonce to follow the security parameters of the AEAD protocol
		incrementNonce(c.send.nonce)
		// write the cipher text to the underlying connection
		if _, er := c.conn.Write(cipherTextBuffer); er != nil {
			return 0, ErrFailedWrite(er)
		}
		// update number of bytes written
		n += chunkSize
		// release the buffers back into the pool for reuse
		pool.Put(cipherTextBuffer)
		pool.Put(plainTextBuffer)
	}
	return
}

// Read() checks the connection for cipher data bytes, if found,
// the func decrypts and loads them into the 'data' buffer