feat(email): add ImapProvider (generic IMAP for unsupported providers)

b3 of the multi-provider email roadmap. Adds ImapConnection model + table (reconciler pattern, SQLite+MySQL), ImapService (MailKit-backed IMAP client), ImapProvider implementing the existing IEmailProvider contract unchanged, and ImapController for credential-based connect (no OAuth — user supplies host/username/password directly, verified by a live connect before storage). Scope, documented inline with ponytail: comments: - INBOX only, no multi-folder support. - Thread grouping approximates the References/In-Reply-To chain root rather than the IMAP THREAD extension, which not every server implements. - External message ids are IMAP UIDs, scoped to the connection's current UIDVALIDITY. Security: ran the security-audit skill against this diff (credential handling + arbitrary-host connect is exactly the class of change the standing security gate exists for). Found and fixed a real SSRF: the connect endpoint let an authenticated user point the server at an arbitrary host:port with no internal-range check, and connect-vs-auth failure was distinguishable to the caller -- together a working oracle to fingerprint internal services (loopback/RFC1918/link-local/cloud metadata) from the server's network position. Fixed with EnsureHostIsExternalAsync (DNS-resolve + reject internal ranges, re-checked on every reconnect to close the DNS-rebinding gap) and a single generic failure message that no longer distinguishes connect vs auth failure. 7 regression tests added. Dependency: MailKit 4.17.0 (MIT license) on JobTrackerBackend.csproj -- stdlib has no IMAP client; hand-rolling IMAP4rev1 (TLS, SASL, MIME parsing) would be a large, security-sensitive protocol implementation nobody asked for, so this is the correct dependency, not a stdlib substitute. 168/168 green (161 existing + 7 new SSRF regression tests; the earlier 14 IMAP feature tests are included in the 161). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-11 18:53:16 +02:00
parent 8edbdceee9
commit a8e2f4dc4a
11 changed files with 849 additions and 1 deletions
@@ -0,0 +1,96 @@
+using System.Security.Claims;
+using JobTrackerApi.Services;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace JobTrackerApi.Controllers;
+
+/// <summary>
+/// Generic IMAP connection lifecycle for mailboxes with no dedicated OAuth provider. Unlike
+/// Gmail/Microsoft, there's no OAuth redirect — the caller submits host/username/password once,
+/// <see cref="IImapService"/> verifies them by connecting, then encrypts and stores them.
+/// </summary>
+[ApiController]
+[Route("api/imap")]
+[Authorize]
+public sealed class ImapController : ControllerBase
+{
+    private readonly IImapService _imap;
+
+    public ImapController(IImapService imap)
+    {
+        _imap = imap;
+    }
+
+    public sealed record ImapConnectRequest(string Host, int Port, bool UseSsl, string Username, string Password);
+
+    public sealed record ImapConnectionStatusDto(
+        bool Connected,
+        string? Host,
+        int? Port,
+        bool? UseSsl,
+        string? Username,
+        DateTimeOffset? ConnectedAt,
+        DateTimeOffset? LastSyncedAt,
+        DateTimeOffset? LastSyncAttemptedAt,
+        DateTimeOffset? LastSyncSucceededAt,
+        string? LastSyncMode,
+        string? LastSyncSource,
+        string? LastSyncStatus,
+        string? LastSyncError);
+
+    [HttpGet("status")]
+    public async Task<ActionResult<ImapConnectionStatusDto>> Status(CancellationToken cancellationToken)
+    {
+        var ownerUserId = GetRequiredOwnerUserId();
+        var connection = await _imap.GetConnectionAsync(ownerUserId, cancellationToken);
+        return Ok(new ImapConnectionStatusDto(
+            connection is not null,
+            connection?.Host,
+            connection?.Port,
+            connection?.UseSsl,
+            connection?.Username,
+            connection?.ConnectedAt,
+            connection?.LastSyncedAt,
+            connection?.LastSyncAttemptedAt,
+            connection?.LastSyncSucceededAt,
+            connection?.LastSyncMode,
+            connection?.LastSyncSource,
+            connection?.LastSyncStatus,
+            connection?.LastSyncError));
+    }
+
+    [HttpPost("connect")]
+    public async Task<IActionResult> Connect([FromBody] ImapConnectRequest request, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(request.Host)) return BadRequest("Host is required.");
+        if (request.Port <= 0 || request.Port > 65535) return BadRequest("Valid port is required.");
+        if (string.IsNullOrWhiteSpace(request.Username)) return BadRequest("Username is required.");
+        if (string.IsNullOrWhiteSpace(request.Password)) return BadRequest("Password is required.");
+
+        var ownerUserId = GetRequiredOwnerUserId();
+        try
+        {
+            var result = await _imap.ConnectAsync(ownerUserId, request.Host, request.Port, request.UseSsl, request.Username, request.Password, cancellationToken);
+            return Ok(new { username = result.Username });
+        }
+        catch (InvalidOperationException ex)
+        {
+            return BadRequest(ex.Message);
+        }
+    }
+
+    [HttpDelete("connection")]
+    public async Task<IActionResult> Disconnect(CancellationToken cancellationToken)
+    {
+        var ownerUserId = GetRequiredOwnerUserId();
+        await _imap.DisconnectAsync(ownerUserId, cancellationToken);
+        return NoContent();
+    }
+
+    private string GetRequiredOwnerUserId()
+    {
+        return User.FindFirstValue(ClaimTypes.NameIdentifier) ?? User.FindFirstValue("sub")
+            ?? throw new InvalidOperationException("Authenticated user id is missing.");
+    }
+}