feat: initial fediverse registration/login

2024-11-03 02:07:07 +01:00 · 2024-11-03 02:07:07 +01:00 · c4cb08cdc1
commit c4cb08cdc1
parent 5a22807410
16 changed files with 467 additions and 111 deletions
--- a/Foxnouns.Backend/Services/Auth/FediverseAuthService.cs
+++ b/Foxnouns.Backend/Services/Auth/FediverseAuthService.cs
@ -0,0 +1,159 @@
+using Foxnouns.Backend.Database;
+using Foxnouns.Backend.Database.Models;
+using Microsoft.EntityFrameworkCore;
+using NodaTime;
+using J = System.Text.Json.Serialization.JsonPropertyNameAttribute;
+
+namespace Foxnouns.Backend.Services.Auth;
+
+public partial class FediverseAuthService
+{
+    private const string NodeInfoRel = "http://nodeinfo.diaspora.software/ns/schema/2.0";
+
+    private readonly ILogger _logger;
+    private readonly HttpClient _client;
+    private readonly DatabaseContext _db;
+    private readonly Config _config;
+    private readonly ISnowflakeGenerator _snowflakeGenerator;
+    private readonly IClock _clock;
+
+    public FediverseAuthService(
+        ILogger logger,
+        Config config,
+        DatabaseContext db,
+        ISnowflakeGenerator snowflakeGenerator,
+        IClock clock
+    )
+    {
+        _config = config;
+        _db = db;
+        _snowflakeGenerator = snowflakeGenerator;
+        _clock = clock;
+        _logger = logger.ForContext<FediverseAuthService>();
+        _client = new HttpClient();
+        _client.DefaultRequestHeaders.Remove("User-Agent");
+        _client.DefaultRequestHeaders.Remove("Accept");
+        _client.DefaultRequestHeaders.Add("User-Agent", $"pronouns.cc/{BuildInfo.Version}");
+        _client.DefaultRequestHeaders.Add("Accept", "application/json");
+    }
+
+    public async Task<string> GenerateAuthUrlAsync(string instance)
+    {
+        var app = await GetApplicationAsync(instance);
+        return await GenerateAuthUrlAsync(app);
+    }
+
+    // thank you, gargron and syuilo, for agreeing on a name for *once* in your lives,
+    // and having both mastodon and misskey use "username" in the self user response
+    public record FediverseUser(
+        [property: J("id")] string Id,
+        [property: J("username")] string Username
+    );
+
+    public async Task<FediverseApplication> GetApplicationAsync(string instance)
+    {
+        var app = await _db.FediverseApplications.FirstOrDefaultAsync(a => a.Domain == instance);
+        if (app != null)
+            return app;
+
+        _logger.Debug("No application for fediverse instance {Instance}, creating it", instance);
+
+        var softwareName = await GetSoftwareNameAsync(instance);
+
+        if (IsMastodonCompatible(softwareName))
+        {
+            return await CreateMastodonApplicationAsync(instance);
+        }
+
+        throw new NotImplementedException();
+    }
+
+    private async Task<string> GetSoftwareNameAsync(string instance)
+    {
+        _logger.Debug("Requesting software name for fediverse instance {Instance}", instance);
+
+        var wellKnownResp = await _client.GetAsync(
+            new Uri($"https://{instance}/.well-known/nodeinfo")
+        );
+        wellKnownResp.EnsureSuccessStatusCode();
+
+        var wellKnown = await wellKnownResp.Content.ReadFromJsonAsync<WellKnownResponse>();
+        var nodeInfoUrl = wellKnown?.Links.FirstOrDefault(l => l.Rel == NodeInfoRel)?.Href;
+        if (nodeInfoUrl == null)
+        {
+            throw new FoxnounsError(
+                $".well-known/nodeinfo response for instance {instance} was invalid, no nodeinfo link"
+            );
+        }
+
+        var nodeInfoResp = await _client.GetAsync(nodeInfoUrl);
+        nodeInfoResp.EnsureSuccessStatusCode();
+
+        var nodeInfo = await nodeInfoResp.Content.ReadFromJsonAsync<PartialNodeInfo>();
+        return nodeInfo?.Software.Name
+            ?? throw new FoxnounsError(
+                $"Nodeinfo response for instance {instance} was invalid, no software name"
+            );
+    }
+
+    private async Task<string> GenerateAuthUrlAsync(FediverseApplication app) =>
+        app.InstanceType switch
+        {
+            FediverseInstanceType.MastodonApi => await GenerateMastodonAuthUrlAsync(app),
+            FediverseInstanceType.MisskeyApi => throw new NotImplementedException(),
+            _ => throw new ArgumentOutOfRangeException(nameof(app), app.InstanceType, null),
+        };
+
+    public async Task<FediverseUser> GetRemoteFediverseUserAsync(
+        FediverseApplication app,
+        string code
+    ) =>
+        app.InstanceType switch
+        {
+            FediverseInstanceType.MastodonApi => await GetMastodonUserAsync(app, code),
+            FediverseInstanceType.MisskeyApi => throw new NotImplementedException(),
+            _ => throw new ArgumentOutOfRangeException(nameof(app), app.InstanceType, null),
+        };
+
+    private static readonly string[] MastodonSoftwareNames =
+    [
+        "mastodon",
+        "hometown",
+        "akkoma",
+        "pleroma",
+        "iceshrimp.net",
+        "iceshrimp",
+        "gotosocial",
+        "pixelfed",
+    ];
+
+    private static readonly string[] MisskeySoftwareNames =
+    [
+        "misskey",
+        "foundkey",
+        "calckey",
+        "firefish",
+        "sharkey",
+    ];
+
+    private static bool IsMastodonCompatible(string softwareName) =>
+        MastodonSoftwareNames.Any(n =>
+            string.Equals(softwareName, n, StringComparison.InvariantCultureIgnoreCase)
+        );
+
+    private static bool IsMisskeyCompatible(string softwareName) =>
+        MisskeySoftwareNames.Any(n =>
+            string.Equals(softwareName, n, StringComparison.InvariantCultureIgnoreCase)
+        );
+
+    private record WellKnownResponse([property: J("links")] WellKnownLink[] Links);
+
+    private record WellKnownLink(
+        [property: J("rel")] string Rel,
+        [property: J("href")] string Href
+    );
+
+    private record PartialNodeInfo([property: J("software")] NodeInfoSoftware Software);
+
+    private record NodeInfoSoftware([property: J("name")] string Name);
+}