Refactor Slack Callback Mechanism (#6388)

* Refactor Slack Callback

* Add more safety to state param, clarify if logic, update tests

* Added an additional 2 possible cases to test: integration is not a slack integration, and the integration has already been claimed

* Implement SonarQube suggestion

* Adjusted org hash to include timestamp; addressed PR feedback

test/Core.Test/AdminConsole/Models/Data/EventIntegrations/IntegrationOAuthStateTests.cs

@@ -0,0 +1,91 @@
+#nullable enable
+
+using Bit.Core.AdminConsole.Entities;
+using Bit.Core.AdminConsole.Models.Data.EventIntegrations;
+using Bit.Test.Common.AutoFixture.Attributes;
+using Microsoft.Extensions.Time.Testing;
+using Xunit;
+
+namespace Bit.Core.Test.AdminConsole.Models.Data.EventIntegrations;
+
+public class IntegrationOAuthStateTests
+{
+    private readonly FakeTimeProvider _fakeTimeProvider = new(
+        new DateTime(2014, 3, 2, 1, 0, 0, DateTimeKind.Utc)
+    );
+
+    [Theory, BitAutoData]
+    public void FromIntegration_ToString_RoundTripsCorrectly(OrganizationIntegration integration)
+    {
+        var state = IntegrationOAuthState.FromIntegration(integration, _fakeTimeProvider);
+        var parsed = IntegrationOAuthState.FromString(state.ToString(), _fakeTimeProvider);
+
+        Assert.NotNull(parsed);
+        Assert.Equal(state.IntegrationId, parsed.IntegrationId);
+        Assert.True(parsed.ValidateOrg(integration.OrganizationId));
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData("not-a-valid-state")]
+    public void FromString_InvalidString_ReturnsNull(string state)
+    {
+        var parsed = IntegrationOAuthState.FromString(state, _fakeTimeProvider);
+
+        Assert.Null(parsed);
+    }
+
+    [Fact]
+    public void FromString_InvalidGuid_ReturnsNull()
+    {
+        var badState = $"not-a-guid.ABCD1234.1706313600";
+
+        var parsed = IntegrationOAuthState.FromString(badState, _fakeTimeProvider);
+
+        Assert.Null(parsed);
+    }
+
+    [Theory, BitAutoData]
+    public void FromString_ExpiredState_ReturnsNull(OrganizationIntegration integration)
+    {
+        var state = IntegrationOAuthState.FromIntegration(integration, _fakeTimeProvider);
+
+        // Advance time 30 minutes to exceed the 20-minute max age
+        _fakeTimeProvider.Advance(TimeSpan.FromMinutes(30));
+
+        var parsed = IntegrationOAuthState.FromString(state.ToString(), _fakeTimeProvider);
+
+        Assert.Null(parsed);
+    }
+
+    [Theory, BitAutoData]
+    public void ValidateOrg_WithCorrectOrgId_ReturnsTrue(OrganizationIntegration integration)
+    {
+        var state = IntegrationOAuthState.FromIntegration(integration, _fakeTimeProvider);
+
+        Assert.True(state.ValidateOrg(integration.OrganizationId));
+    }
+
+    [Theory, BitAutoData]
+    public void ValidateOrg_WithWrongOrgId_ReturnsFalse(OrganizationIntegration integration)
+    {
+        var state = IntegrationOAuthState.FromIntegration(integration, _fakeTimeProvider);
+
+        Assert.False(state.ValidateOrg(Guid.NewGuid()));
+    }
+
+    [Theory, BitAutoData]
+    public void ValidateOrg_ModifiedTimestamp_ReturnsFalse(OrganizationIntegration integration)
+    {
+        var state = IntegrationOAuthState.FromIntegration(integration, _fakeTimeProvider);
+        var parts = state.ToString().Split('.');
+
+        parts[2] = $"{_fakeTimeProvider.GetUtcNow().ToUnixTimeSeconds() - 1}";
+        var modifiedState = IntegrationOAuthState.FromString(string.Join(".", parts), _fakeTimeProvider);
+
+        Assert.True(state.ValidateOrg(integration.OrganizationId));
+        Assert.NotNull(modifiedState);
+        Assert.False(modifiedState.ValidateOrg(integration.OrganizationId));
+    }
+}

test/Core.Test/AdminConsole/Services/SlackServiceTests.cs

@@ -2,6 +2,7 @@
 
 using System.Net;
 using System.Text.Json;
+using System.Web;
 using Bit.Core.Services;
 using Bit.Test.Common.AutoFixture;
 using Bit.Test.Common.AutoFixture.Attributes;
@@ -261,10 +262,19 @@ public class SlackServiceTests
         var sutProvider = GetSutProvider();
         var clientId = sutProvider.GetDependency<GlobalSettings>().Slack.ClientId;
         var scopes = sutProvider.GetDependency<GlobalSettings>().Slack.Scopes;
-        var redirectUrl = "https://example.com/callback";
-        var expectedUrl = $"https://slack.com/oauth/v2/authorize?client_id={clientId}&scope={scopes}&redirect_uri={redirectUrl}";
-        var result = sutProvider.Sut.GetRedirectUrl(redirectUrl);
-        Assert.Equal(expectedUrl, result);
+        var callbackUrl = "https://example.com/callback";
+        var state = Guid.NewGuid().ToString();
+        var result = sutProvider.Sut.GetRedirectUrl(callbackUrl, state);
+
+        var uri = new Uri(result);
+        var query = HttpUtility.ParseQueryString(uri.Query);
+
+        Assert.Equal(clientId, query["client_id"]);
+        Assert.Equal(scopes, query["scope"]);
+        Assert.Equal(callbackUrl, query["redirect_uri"]);
+        Assert.Equal(state, query["state"]);
+        Assert.Equal("slack.com", uri.Host);
+        Assert.Equal("/oauth/v2/authorize", uri.AbsolutePath);
     }
 
     [Fact]