/src/grpc-swift/Sources/GRPC/MessageEncodingHeaderValidator.swift
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1 | | /* |
2 | | * Copyright 2020, gRPC Authors All rights reserved. |
3 | | * |
4 | | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | | * you may not use this file except in compliance with the License. |
6 | | * You may obtain a copy of the License at |
7 | | * |
8 | | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | | * |
10 | | * Unless required by applicable law or agreed to in writing, software |
11 | | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | | * See the License for the specific language governing permissions and |
14 | | * limitations under the License. |
15 | | */ |
16 | | |
17 | | struct MessageEncodingHeaderValidator { |
18 | | var encoding: ServerMessageEncoding |
19 | | |
20 | | enum ValidationResult { |
21 | | /// The requested compression is supported. |
22 | | case supported( |
23 | | algorithm: CompressionAlgorithm, |
24 | | decompressionLimit: DecompressionLimit, |
25 | | acceptEncoding: [String] |
26 | | ) |
27 | | |
28 | | /// The `requestEncoding` is not supported; `acceptEncoding` contains all algorithms we do |
29 | | /// support. |
30 | | case unsupported(requestEncoding: String, acceptEncoding: [String]) |
31 | | |
32 | | /// No compression was requested. |
33 | | case noCompression |
34 | | } |
35 | | |
36 | | /// Validates the value of the 'grpc-encoding' header against compression algorithms supported and |
37 | | /// advertised by this peer. |
38 | | /// |
39 | | /// - Parameter requestEncoding: The value of the 'grpc-encoding' header. |
40 | 105k | func validate(requestEncoding: String?) -> ValidationResult { |
41 | 105k | switch (self.encoding, requestEncoding) { |
42 | 105k | // Compression is enabled and the client sent a message encoding header. Do we support it? |
43 | 105k | case let (.enabled(configuration), .some(header)): |
44 | 0 | guard let algorithm = CompressionAlgorithm(rawValue: header) else { |
45 | 0 | return .unsupported( |
46 | 0 | requestEncoding: header, |
47 | 0 | acceptEncoding: configuration.enabledAlgorithms.map { $0.name } |
48 | 0 | ) |
49 | 0 | } |
50 | 0 |
|
51 | 0 | if configuration.enabledAlgorithms.contains(algorithm) { |
52 | 0 | return .supported( |
53 | 0 | algorithm: algorithm, |
54 | 0 | decompressionLimit: configuration.decompressionLimit, |
55 | 0 | acceptEncoding: [] |
56 | 0 | ) |
57 | 0 | } else { |
58 | 0 | // From: https://github.com/grpc/grpc/blob/master/doc/compression.md |
59 | 0 | // |
60 | 0 | // Note that a peer MAY choose to not disclose all the encodings it supports. However, if |
61 | 0 | // it receives a message compressed in an undisclosed but supported encoding, it MUST |
62 | 0 | // include said encoding in the response's grpc-accept-encoding header. |
63 | 0 | return .supported( |
64 | 0 | algorithm: algorithm, |
65 | 0 | decompressionLimit: configuration.decompressionLimit, |
66 | 0 | acceptEncoding: configuration.enabledAlgorithms.map { $0.name } + CollectionOfOne(header) |
67 | 0 | ) |
68 | 0 | } |
69 | 105k | |
70 | 105k | // Compression is disabled and the client sent a message encoding header. We don't support this |
71 | 105k | // unless the header is "identity", which is no compression. Note this is different to the |
72 | 105k | // supported but not advertised case since we have explicitly not enabled compression. |
73 | 105k | case let (.disabled, .some(header)): |
74 | 918 | guard let algorithm = CompressionAlgorithm(rawValue: header) else { |
75 | 410 | return .unsupported( |
76 | 410 | requestEncoding: header, |
77 | 410 | acceptEncoding: [] |
78 | 410 | ) |
79 | 508 | } |
80 | 508 | |
81 | 508 | if algorithm == .identity { |
82 | 198 | return .noCompression |
83 | 310 | } else { |
84 | 310 | return .unsupported(requestEncoding: header, acceptEncoding: []) |
85 | 310 | } |
86 | 105k | |
87 | 105k | // The client didn't send a message encoding header. |
88 | 105k | case (_, .none): |
89 | 104k | return .noCompression |
90 | 105k | } |
91 | 105k | } |
92 | | } |