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extract common classes for server request decompressor (#60)
* extract common classes for server request decompressor * review fix: make fields private and make state part of the handler * review fixes * review fix: reserve capacity before inflating
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // This source file is part of the SwiftNIO open source project | ||
| // | ||
| // Copyright (c) 2019 Apple Inc. and the SwiftNIO project authors | ||
| // Licensed under Apache License v2.0 | ||
| // | ||
| // See LICENSE.txt for license information | ||
| // See CONTRIBUTORS.txt for the list of SwiftNIO project authors | ||
| // | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
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| import CNIOExtrasZlib | ||
| import NIO | ||
|
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| public enum NIOHTTPDecompression { | ||
| /// Specifies how to limit decompression inflation. | ||
| public struct DecompressionLimit { | ||
| private enum Limit { | ||
| case none | ||
| case size(Int) | ||
| case ratio(Int) | ||
| } | ||
|
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| private var limit: Limit | ||
|
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| /// No limit will be set. | ||
| public static let none = DecompressionLimit(limit: .none) | ||
| /// Limit will be set on the request body size. | ||
| public static func size(_ value: Int) -> DecompressionLimit { return DecompressionLimit(limit: .size(value)) } | ||
| /// Limit will be set on a ratio between compressed body size and decompressed result. | ||
| public static func ratio(_ value: Int) -> DecompressionLimit { return DecompressionLimit(limit: .ratio(value)) } | ||
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| func exceeded(compressed: Int, decompressed: Int) -> Bool { | ||
| switch self.limit { | ||
| case .none: | ||
| return false | ||
| case .size(let allowed): | ||
| return compressed > allowed | ||
| case .ratio(let ratio): | ||
| return decompressed > compressed * ratio | ||
| } | ||
| } | ||
| } | ||
|
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| public enum DecompressionError: Error { | ||
| case limit | ||
| case inflationError(Int) | ||
| case initializationError(Int) | ||
| } | ||
|
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| enum CompressionAlgorithm: String { | ||
| case gzip | ||
| case deflate | ||
|
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| init?(header: String?) { | ||
| switch header { | ||
| case .some("gzip"): | ||
| self = .gzip | ||
| case .some("deflate"): | ||
| self = .deflate | ||
| default: | ||
| return nil | ||
| } | ||
| } | ||
|
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| var window: CInt { | ||
| switch self { | ||
| case .deflate: | ||
| return 15 | ||
| case .gzip: | ||
| return 15 + 16 | ||
| } | ||
| } | ||
| } | ||
|
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| struct Decompressor { | ||
| private let limit: NIOHTTPDecompression.DecompressionLimit | ||
| private var stream = z_stream() | ||
| private var inflated = 0 | ||
|
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| init(limit: NIOHTTPDecompression.DecompressionLimit) { | ||
| self.limit = limit | ||
| } | ||
|
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| mutating func decompress(part: inout ByteBuffer, buffer: inout ByteBuffer, originalLength: Int) throws { | ||
| buffer.reserveCapacity(part.readableBytes * 2) | ||
|
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| self.inflated += try self.stream.inflatePart(input: &part, output: &buffer) | ||
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| if self.limit.exceeded(compressed: originalLength, decompressed: self.inflated) { | ||
| throw NIOHTTPDecompression.DecompressionError.limit | ||
| } | ||
| } | ||
|
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| mutating func initializeDecoder(encoding: NIOHTTPDecompression.CompressionAlgorithm, length: Int) throws { | ||
| self.stream.zalloc = nil | ||
| self.stream.zfree = nil | ||
| self.stream.opaque = nil | ||
|
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| let rc = CNIOExtrasZlib_inflateInit2(&self.stream, encoding.window) | ||
| guard rc == Z_OK else { | ||
| throw NIOHTTPDecompression.DecompressionError.initializationError(Int(rc)) | ||
| } | ||
| } | ||
|
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| mutating func deinitializeDecoder() { | ||
| inflateEnd(&self.stream) | ||
| } | ||
| } | ||
| } | ||
|
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| extension z_stream { | ||
| mutating func inflatePart(input: inout ByteBuffer, output: inout ByteBuffer) throws -> Int { | ||
| var written = 0 | ||
| try input.readWithUnsafeMutableReadableBytes { pointer in | ||
| self.avail_in = UInt32(pointer.count) | ||
| self.next_in = CNIOExtrasZlib_voidPtr_to_BytefPtr(pointer.baseAddress!) | ||
|
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| defer { | ||
| self.avail_in = 0 | ||
| self.next_in = nil | ||
| self.avail_out = 0 | ||
| self.next_out = nil | ||
| } | ||
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| written += try self.inflatePart(to: &output) | ||
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| return pointer.count - Int(self.avail_in) | ||
| } | ||
| return written | ||
| } | ||
|
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| private mutating func inflatePart(to buffer: inout ByteBuffer) throws -> Int { | ||
| return try buffer.writeWithUnsafeMutableBytes { pointer in | ||
| self.avail_out = UInt32(pointer.count) | ||
| self.next_out = CNIOExtrasZlib_voidPtr_to_BytefPtr(pointer.baseAddress!) | ||
|
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| let rc = inflate(&self, Z_NO_FLUSH) | ||
| guard rc == Z_OK || rc == Z_STREAM_END else { | ||
| throw NIOHTTPDecompression.DecompressionError.inflationError(Int(rc)) | ||
| } | ||
|
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| return pointer.count - Int(self.avail_out) | ||
| } | ||
| } | ||
| } |
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