SocialPub/PrivaPub.Tests/Support/RemoteActor.cs

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;

using PrivaPub.Federation.Signing;

using System.Globalization;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json.Nodes;

namespace PrivaPub.Tests.Support
{
	public sealed class RemoteActor
	{
		readonly RSA _key = RSA.Create(2048);

		public RemoteActor(Peer peer, string name, string origin = default)
		{
			Name = $"{name}{Guid.NewGuid():N}"[..20];
			Id = $"{origin ?? peer.A}/users/{Name}";
			peer.Serve($"/users/{Name}", Document().ToJsonString());
		}

		public string Name { get; }
		public string Id { get; }
		public string KeyId => Id + "#main-key";
		public string SharedInbox => Id.Split("/users/")[0] + "/inbox";

		public JsonObject Document() => new()
		{
			["id"] = Id,
			["type"] = "Person",
			["preferredUsername"] = Name,
			["inbox"] = Id + "/inbox",
			["followers"] = Id + "/followers",
			["publicKey"] = new JsonObject
			{
				["id"] = KeyId,
				["owner"] = Id,
				["publicKeyPem"] = _key.ExportSubjectPublicKeyInfoPem()
			}
		};

		public HttpRequest Post(string host, string path, JsonNode activity)
		{
			var body = Encoding.UTF8.GetBytes(activity.ToJsonString());
			var date = DateTimeOffset.UtcNow.ToString("r", CultureInfo.InvariantCulture);
			var digest = HttpSignatures.Digest(body);
			var signingString = $"(request-target): post {path}\nhost: {host}\ndate: {date}\ndigest: {digest}";
			var signature = Convert.ToBase64String(_key.SignData(Encoding.UTF8.GetBytes(signingString), HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1));

			var context = new DefaultHttpContext();
			context.Request.Method = "POST";
			context.Request.Host = new HostString(host);
			context.Request.Path = path;
			context.Features.Get<IHttpRequestFeature>().RawTarget = path;
			context.Request.Headers["Date"] = date;
			context.Request.Headers["Digest"] = digest;
			context.Request.Headers["Content-Type"] = "application/activity+json";
			context.Request.Headers["Signature"] = $"keyId=\"{KeyId}\",algorithm=\"rsa-sha256\",headers=\"(request-target) host date digest\",signature=\"{signature}\"";
			context.Request.Body = new MemoryStream(body);
			context.Request.ContentLength = body.Length;
			return context.Request;
		}
	}
}