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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Globalization;
#if !COMPONENTS
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing.Matching;
#else
using Microsoft.AspNetCore.Components.Routing;
#endif
namespace Microsoft.AspNetCore.Routing.Constraints;
#if !COMPONENTS
/// <summary>
/// Constrains a route parameter to represent only non-file-name values. Does not validate that
/// the route value contains valid file system characters, or that the value represents
/// an actual file on disk.
/// </summary>
/// <remarks>
/// <para>
/// This constraint can be used to disambiguate requests for dynamic content versus
/// static files served from the application.
/// </para>
/// <para>
/// This constraint determines whether a route value represents a file name by examining
/// the last URL Path segment of the value (delimited by <c>/</c>). The last segment
/// must contain the dot (<c>.</c>) character followed by one or more non-(<c>.</c>) characters.
/// </para>
/// <para>
/// If the route value does not contain a <c>/</c> then the entire value will be interpreted
/// as a the last segment.
/// </para>
/// <para>
/// The <see cref="NonFileNameRouteConstraint"/> does not attempt to validate that the value contains
/// a legal file name for the current operating system.
/// </para>
/// <para>
/// <list type="bullet">
/// <listheader>
/// <term>Examples of route values that will be matched as non-file-names</term>
/// <description>description</description>
/// </listheader>
/// <item>
/// <term><c>/a/b/c</c></term>
/// <description>Final segment does not contain a <c>.</c>.</description>
/// </item>
/// <item>
/// <term><c>/a/b.d/c</c></term>
/// <description>Final segment does not contain a <c>.</c>.</description>
/// </item>
/// <item>
/// <term><c>/a/b.d/c/</c></term>
/// <description>Final segment is empty.</description>
/// </item>
/// <item>
/// <term><c></c></term>
/// <description>Value is empty</description>
/// </item>
/// </list>
/// <list type="bullet">
/// <listheader>
/// <term>Examples of route values that will be rejected as file names</term>
/// <description>description</description>
/// </listheader>
/// <item>
/// <term><c>/a/b/c.txt</c></term>
/// <description>Final segment contains a <c>.</c> followed by other characters.</description>
/// </item>
/// <item>
/// <term><c>/hello.world.txt</c></term>
/// <description>Final segment contains a <c>.</c> followed by other characters.</description>
/// </item>
/// <item>
/// <term><c>hello.world.txt</c></term>
/// <description>Final segment contains a <c>.</c> followed by other characters.</description>
/// </item>
/// <item>
/// <term><c>.gitignore</c></term>
/// <description>Final segment contains a <c>.</c> followed by other characters.</description>
/// </item>
/// </list>
/// </para>
/// </remarks>
public class NonFileNameRouteConstraint : IRouteConstraint, IParameterLiteralNodeMatchingPolicy, ICachableParameterPolicy
#else
internal class NonFileNameRouteConstraint : IRouteConstraint
#endif
{
/// <inheritdoc />
public bool Match(
#if !COMPONENTS
HttpContext? httpContext,
IRouter? route,
string routeKey,
RouteValueDictionary values,
RouteDirection routeDirection)
#else
string routeKey,
RouteValueDictionary values)
#endif
{
ArgumentNullException.ThrowIfNull(routeKey);
ArgumentNullException.ThrowIfNull(values);
if (values.TryGetValue(routeKey, out var obj) && obj != null)
{
var value = Convert.ToString(obj, CultureInfo.InvariantCulture);
return !FileNameRouteConstraint.IsFileName(value);
}
// No value or null value.
//
// We want to return true here because the core use-case of the constraint is to *exclude*
// things that look like file names. There's nothing here that looks like a file name, so
// let it through.
return true;
}
#if !COMPONENTS
bool IParameterLiteralNodeMatchingPolicy.MatchesLiteral(string parameterName, string literal)
{
return !FileNameRouteConstraint.IsFileName(literal);
}
#endif
}
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