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Merge pull request #698 from mmdriley/uri
Add UriPatcher to fix URI quirks
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| Copyright 2016 Google Inc | ||
| Licensed under the Apache License, Version 2.0(the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
|
|
||
| using System; | ||
| using System.Reflection; | ||
|
|
||
| namespace Google.Apis.Util | ||
| { | ||
| // UriPatcher lets us work around some unfortunate behaviors in the .NET Framework's | ||
| // implementation of System.Uri. | ||
| // | ||
| // == Problem 1: Slashes and dots | ||
| // | ||
| // Prior to .NET 4.5, System.Uri would always unescape "%2f" ("/") and "%5c" ("\\"). | ||
| // Relative path components were also compressed. | ||
| // | ||
| // As a result, this: "http://www.example.com/.%2f.%5c./" | ||
| // ... turned into this: "http://www.example.com/" | ||
| // | ||
| // This breaks API requests where slashes or dots appear in path parameters. Such requests | ||
| // arise, for example, when these characters appear in the name of a GCS object. | ||
| // | ||
| // == Problem 2: Fewer unreserved characters | ||
| // | ||
| // Unless IDN/IRI parsing is enabled -- which it is not, by default, prior to .NET 4.5 -- | ||
| // Uri.EscapeDataString uses the set of "unreserved" characters from RFC 2396 instead of the | ||
| // newer, *smaller* list from RFC 3986. We build requests using URI templating as described | ||
| // by RFC 6570, which specifies that the latter definition (RFC 3986) should be used. | ||
| // | ||
| // This breaks API requests with parameters including any of: !*'() | ||
| // | ||
| // == Solutions | ||
| // | ||
| // Though the default behaviors changed in .NET 4.5, these "quirks" remain for compatibility | ||
| // unless the application explicitly targets the new runtime. Usually, that means adding a | ||
| // TargetFrameworkAttribute to the entry assembly. | ||
| // | ||
| // Applications running on .NET 4.0 or later can also set "DontUnescapePathDotsAndSlashes" | ||
| // and enable IDN/IRI parsing using app.config or web.config. | ||
| // | ||
| // As a class library, we can't control app.config or the entry assembly, so we can't take | ||
| // either approach. Instead, we resort to reflection trickery to try to solve these problems | ||
| // if we detect they exist. Sorry. | ||
| internal static class UriPatcher | ||
| { | ||
| internal static void PatchUriQuirks() | ||
| { | ||
| var uriParser = typeof(System.Uri).Assembly.GetType("System.UriParser"); | ||
| if (uriParser == null) { return; } | ||
|
|
||
| // Is "%2f" unescaped for http: or https: URIs? | ||
| if (new Uri("http://example.com/%2f").AbsolutePath == "//" || | ||
| new Uri("https://example.com/%2f").AbsolutePath == "//") | ||
| { | ||
| // Call System.UriParser.Http[s]Uri.SetUpdatableFlags(UriSyntaxFlags.None) | ||
| // https://github.com/Microsoft/referencesource/blob/d925d870f3cb3f6a/System/net/System/_UriSyntax.cs#L87 | ||
| // https://github.com/Microsoft/referencesource/blob/d925d870f3cb3f6a/System/net/System/_UriSyntax.cs#L77 | ||
| // https://github.com/Microsoft/referencesource/blob/d925d870f3cb3f6a/System/net/System/_UriSyntax.cs#L352 | ||
|
|
||
| var setUpdatableFlagsMethod = uriParser.GetMethod("SetUpdatableFlags", | ||
| BindingFlags.Instance | BindingFlags.NonPublic); | ||
| if (setUpdatableFlagsMethod != null) | ||
| { | ||
| Action<string> setUriParserUpdatableFlags = (fieldName) => | ||
| { | ||
| var parserField = uriParser.GetField(fieldName, | ||
| BindingFlags.Static | BindingFlags.NonPublic); | ||
| if (parserField == null) { return; } | ||
| var parserInstance = parserField.GetValue(null); | ||
| if (parserInstance == null) { return; } | ||
| setUpdatableFlagsMethod.Invoke(parserInstance, new object[] { 0 }); | ||
| }; | ||
|
|
||
| // Make the change for the http: and https: URI parsers. | ||
| setUriParserUpdatableFlags("HttpUri"); | ||
| setUriParserUpdatableFlags("HttpsUri"); | ||
| } | ||
| } | ||
|
|
||
| // Is "*" considered "unreserved"? | ||
| if (Uri.EscapeDataString("*") == "*") | ||
| { | ||
| // Set UriParser.s_QuirksVersion to at least UriQuirksVersion.V3 | ||
| // https://github.com/Microsoft/referencesource/blob/d925d870f3cb3f6a/System/net/System/_UriSyntax.cs#L114 | ||
| // https://github.com/Microsoft/referencesource/blob/d925d870f3cb3f6a/System/net/System/UriHelper.cs#L701 | ||
|
|
||
| var quirksField = uriParser.GetField("s_QuirksVersion", | ||
| BindingFlags.Static | BindingFlags.NonPublic); | ||
| if (quirksField != null) | ||
| { | ||
| int quirksVersion = (int)quirksField.GetValue(null); | ||
| if (quirksVersion <= 2) | ||
| { | ||
| quirksField.SetValue(null, 3); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |
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