grpc/src/csharp/Grpc.Auth/AuthInterceptors.cs

#region Copyright notice and license

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// modification, are permitted provided that the following conditions are
// met:
//
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// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
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#endregion

using System;
using System.Threading;

using Google.Apis.Auth.OAuth2;
using Grpc.Core;
using Grpc.Core.Utils;

namespace Grpc.Auth
{
    /// <summary>
    /// Factory methods to create authorization interceptors.
    /// <seealso cref="GrpcCredentials"/>
    /// </summary>
    public static class AuthInterceptors
    {
        private const string AuthorizationHeader = "Authorization";
        private const string Schema = "Bearer";

        /// <summary>
        /// Creates an <see cref="AsyncAuthInterceptor"/> that will obtain access token from any credential type that implements
        /// <c>ITokenAccess</c>. (e.g. <c>GoogleCredential</c>).
        /// </summary>
        /// <param name="credential">The credential to use to obtain access tokens.</param>
        /// <returns>The interceptor.</returns>
        public static AsyncAuthInterceptor FromCredential(ITokenAccess credential)
        {
            return new AsyncAuthInterceptor(async (authUri, metadata) =>
            {
                var accessToken = await credential.GetAccessTokenForRequestAsync(authUri, CancellationToken.None).ConfigureAwait(false);
                metadata.Add(CreateBearerTokenHeader(accessToken));
            });
        }

        /// <summary>
        /// Creates an <see cref="AsyncAuthInterceptor"/> that will use given access token as authorization.
        /// </summary>
        /// <param name="accessToken">OAuth2 access token.</param>
        /// <returns>The interceptor.</returns>
        public static AsyncAuthInterceptor FromAccessToken(string accessToken)
        {
            Preconditions.CheckNotNull(accessToken);
            return new AsyncAuthInterceptor(async (authUri, metadata) =>
            {
                metadata.Add(CreateBearerTokenHeader(accessToken));
            });
        }

        private static Metadata.Entry CreateBearerTokenHeader(string accessToken)
        {
            return new Metadata.Entry(AuthorizationHeader, Schema + " " + accessToken);
        }
    }
}