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https://github.com/apple/swift-nio-extras.git
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ad4edc8cb5
* Adds a line-based frame decoder that can split received buffers on line endings. Motivation: As per https://github.com/apple/swift-nio/issues/473 Modifications: Added a new decoder (LineBasedFrameDecoder) that splits incoming buffers on line end characters. Result: Received buffers will be split on line end character(s) ('\n' or '\r\n'), with these characters stripped in the resulting buffers.
93 lines
3.2 KiB
Swift
93 lines
3.2 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the SwiftNIO open source project
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//
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// Copyright (c) 2017-2018 Apple Inc. and the SwiftNIO project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import NIO
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/// A decoder that splits incoming `ByteBuffer`s around line end
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/// character(s) (`'\n'` or `'\r\n'`).
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///
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/// Let's, for example, consider the following received buffer:
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///
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/// +----+-------+------------+
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/// | AB | C\nDE | F\r\nGHI\n |
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/// +----+-------+------------+
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///
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/// A instance of `LineBasedFrameDecoder` will split this buffer
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/// as follows:
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///
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/// +-----+-----+-----+
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/// | ABC | DEF | GHI |
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/// +-----+-----+-----+
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///
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public class LineBasedFrameDecoder: ByteToMessageDecoder {
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public typealias InboundIn = ByteBuffer
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public typealias InboundOut = ByteBuffer
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public var cumulationBuffer: ByteBuffer?
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// keep track of the last scan offset from the buffer's reader index (if we didn't find the delimiter)
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private var lastScanOffset = 0
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public init() { }
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public func decode(ctx: ChannelHandlerContext, buffer: inout ByteBuffer) throws -> DecodingState {
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if let frame = try self.findNextFrame(buffer: &buffer) {
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ctx.fireChannelRead(wrapInboundOut(frame))
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return .continue
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} else {
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return .needMoreData
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}
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}
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private func findNextFrame(buffer: inout ByteBuffer) throws -> ByteBuffer? {
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let view = buffer.readableBytesView.dropFirst(self.lastScanOffset)
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// look for the delimiter
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if let delimiterIndex = view.firstIndex(of: 0x0A) { // '\n'
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let length = delimiterIndex - buffer.readerIndex
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let dropCarriageReturn = delimiterIndex > view.startIndex && view[delimiterIndex - 1] == 0x0D // '\r'
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let buff = buffer.readSlice(length: dropCarriageReturn ? length - 1 : length)
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// drop the delimiter (and trailing carriage return if appicable)
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buffer.moveReaderIndex(forwardBy: dropCarriageReturn ? 2 : 1)
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// reset the last scan start index since we found a line
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self.lastScanOffset = 0
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return buff
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}
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// next scan we start where we stopped
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self.lastScanOffset = buffer.readableBytes
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return nil
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}
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public func handlerRemoved(ctx: ChannelHandlerContext) {
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self.handleLeftOverBytes(ctx: ctx)
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}
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public func channelInactive(ctx: ChannelHandlerContext) {
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self.handleLeftOverBytes(ctx: ctx)
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}
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private func handleLeftOverBytes(ctx: ChannelHandlerContext) {
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if let buffer = self.cumulationBuffer, buffer.readableBytes > 0 {
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self.cumulationBuffer?.clear()
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ctx.fireErrorCaught(NIOExtrasErrors.LeftOverBytesError(leftOverBytes: buffer))
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}
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}
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}
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#if !swift(>=4.2)
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private extension ByteBufferView {
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func firstIndex(of element: UInt8) -> Int? {
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return self.index(of: element)
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}
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}
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#endif
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