mirror of
https://github.com/apple/swift-nio-extras.git
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84 lines
3.0 KiB
Swift
84 lines
3.0 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) 2017-2021 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 NIOCore
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///
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/// A decoder that splits the received `ByteBuffer` by a fixed number
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/// of bytes. For example, if you received the following four fragmented packets:
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///
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/// +---+----+------+----+
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/// | A | BC | DEFG | HI |
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/// +---+----+------+----+
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///
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/// A ``FixedLengthFrameDecoder`` will decode them into the
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/// following three packets with the fixed length:
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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 final class FixedLengthFrameDecoder: ByteToMessageDecoder {
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/// Data type we receive.
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public typealias InboundIn = ByteBuffer
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/// Data type we send to the next stage.
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public typealias InboundOut = ByteBuffer
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@available(*, deprecated, message: "No longer used")
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public var cumulationBuffer: ByteBuffer?
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private let frameLength: Int
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/// Create `FixedLengthFrameDecoder` with a given frame length.
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///
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/// - parameters:
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/// - frameLength: The length of a frame.
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public init(frameLength: Int) {
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self.frameLength = frameLength
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}
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/// Get a frame of data and `fireChannelRead` if sufficient data exists in the buffer.
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/// - Parameters:
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/// - context: Calling context.
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/// - buffer: Buffer containing data.
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/// - Returns: Status detailing if more data is required or if a successful decode occurred.
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public func decode(context: ChannelHandlerContext, buffer: inout ByteBuffer) throws -> DecodingState {
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guard let slice = buffer.readSlice(length: frameLength) else {
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return .needMoreData
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}
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context.fireChannelRead(self.wrapInboundOut(slice))
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return .continue
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}
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/// Repeatedly decode frames until there is not enough data to decode any more.
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/// Reports an error through `fireErrorCaught` if this doesn't empty the buffer exactly.
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/// - Parameters:
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/// - context: Calling context
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/// - buffer: Buffer containing data.
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/// - seenEOF: If end of file has been seen.
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/// - Returns: needMoreData always as all data is consumed.
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public func decodeLast(context: ChannelHandlerContext, buffer: inout ByteBuffer, seenEOF: Bool) throws -> DecodingState {
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while case .continue = try self.decode(context: context, buffer: &buffer) {}
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if buffer.readableBytes > 0 {
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context.fireErrorCaught(NIOExtrasErrors.LeftOverBytesError(leftOverBytes: buffer))
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}
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return .needMoreData
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}
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}
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#if swift(>=5.6)
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@available(*, unavailable)
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extension FixedLengthFrameDecoder: Sendable {}
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#endif
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