File: CorsServiceCollectionExtensions.cs
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Project: src\aspnetcore\src\Middleware\CORS\src\Microsoft.AspNetCore.Cors.csproj (Microsoft.AspNetCore.Cors)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.AspNetCore.Cors.Infrastructure;
using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Microsoft.Extensions.DependencyInjection;

/// <summary>
/// Extension methods for setting up cross-origin resource sharing services in an <see cref="IServiceCollection" />.
/// </summary>
public static class CorsServiceCollectionExtensions
{
    /// <summary>
    /// Adds cross-origin resource sharing services to the specified <see cref="IServiceCollection" />.
    /// </summary>
    /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
    /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
    public static IServiceCollection AddCors(this IServiceCollection services)
    {
        ArgumentNullException.ThrowIfNull(services);

        services.AddOptions();

        services.TryAdd(ServiceDescriptor.Transient<ICorsService, CorsService>());
        services.TryAdd(ServiceDescriptor.Transient<ICorsPolicyProvider, DefaultCorsPolicyProvider>());

        return services;
    }

    /// <summary>
    /// Adds cross-origin resource sharing services to the specified <see cref="IServiceCollection" />.
    /// </summary>
    /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
    /// <param name="setupAction">An <see cref="Action{CorsOptions}"/> to configure the provided <see cref="CorsOptions"/>.</param>
    /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
    public static IServiceCollection AddCors(this IServiceCollection services, Action<CorsOptions> setupAction)
    {
        ArgumentNullException.ThrowIfNull(services);
        ArgumentNullException.ThrowIfNull(setupAction);

        services.AddCors();
        services.Configure(setupAction);

        return services;
    }
}