[#25] - include client allowed audiences in user access token

Applications/Backend/Source/HttpsRichardy.Federation.Application/Handlers/Authorization/AuthorizationCodeGrantHandler.cs

@@ -1,6 +1,6 @@
 namespace HttpsRichardy.Federation.Application.Handlers.Authorization;
 
-public sealed class AuthorizationCodeGrantHandler(IRealmCollection realmCollection, IUserCollection userCollection, ISecurityTokenService tokenService, ITokenCollection tokenCollection) :
+public sealed class AuthorizationCodeGrantHandler(IRealmCollection realmCollection, IUserCollection userCollection, IClientCollection clientCollection, ISecurityTokenService tokenService, ITokenCollection tokenCollection) :
     IAuthorizationFlowHandler
 {
     public Grant Grant => Grant.AuthorizationCode;
@@ -38,6 +38,24 @@ public async Task<Result<ClientAuthenticationResult>> HandleAsync(
             return Result<ClientAuthenticationResult>.Failure(AuthenticationErrors.ClientNotFound);
         }
 
+        var clientFilters = new ClientFiltersBuilder()
+            .WithClientId(parameters.ClientId)
+            .Build();
+
+        var clients = await clientCollection.GetClientsAsync(clientFilters, cancellation: cancellation);
+        var client = clients.FirstOrDefault();
+
+        if (client is null || !string.Equals(client.RealmId, token.RealmId, StringComparison.Ordinal))
+        {
+            return Result<ClientAuthenticationResult>.Failure(AuthorizationErrors.InvalidAuthorizationCode);
+        }
+
+        var boundClientId = token.Metadata.GetValueOrDefault("client.id");
+        if (!string.Equals(boundClientId, parameters.ClientId, StringComparison.Ordinal))
+        {
+            return Result<ClientAuthenticationResult>.Failure(AuthorizationErrors.InvalidAuthorizationCode);
+        }
+
         var codeChallenge = token.Metadata.GetValueOrDefault("code.challenge")!;
         var codeChallengeMethod = token.Metadata.GetValueOrDefault("code.challenge.method")!;
 
@@ -58,7 +76,7 @@ public async Task<Result<ClientAuthenticationResult>> HandleAsync(
             return Result<ClientAuthenticationResult>.Failure(AuthenticationErrors.UserNotFound);
         }
 
-        var tokenResult = await tokenService.GenerateAccessTokenAsync(user, cancellation);
+        var tokenResult = await tokenService.GenerateAccessTokenAsync(user, client.Audiences, cancellation);
         if (tokenResult.IsFailure || tokenResult.Data is null)
         {
             return Result<ClientAuthenticationResult>.Failure(tokenResult.Error);

Applications/Backend/Source/HttpsRichardy.Federation.Application/Services/ISecurityTokenService.cs

@@ -7,6 +7,12 @@ public Task<Result<SecurityToken>> GenerateAccessTokenAsync(
         CancellationToken cancellation = default
     );
 
+    public Task<Result<SecurityToken>> GenerateAccessTokenAsync(
+        User user,
+        IEnumerable<Audience> audiences,
+        CancellationToken cancellation = default
+    );
+
     public Task<Result<SecurityToken>> GenerateAccessTokenAsync(
         Client client,
         CancellationToken cancellation = default
@@ -31,4 +37,4 @@ public Task<Result> RevokeRefreshTokenAsync(
         SecurityToken token,
         CancellationToken cancellation = default
     );
-}
+}

Applications/Backend/Source/HttpsRichardy.Federation.Application/Validators/Identity/ClientAuthenticationCredentialsValidator.cs

@@ -27,6 +27,12 @@ public ClientAuthenticationCredentialsValidator()
 
         When(credential => credential.GrantType == SupportedGrantType.AuthorizationCode, () =>
         {
+            RuleFor(credential => credential.ClientId)
+                .NotEmpty()
+                .WithMessage("client identifier must not be empty.")
+                .MaximumLength(200)
+                .WithMessage("client identifier must be at most 200 characters long.");
+
             RuleFor(credential => credential.Code)
                 .NotEmpty()
                 .WithMessage("code must not be empty.");

Applications/Backend/Source/HttpsRichardy.Federation.Infrastructure/Security/JwtSecurityTokenService.cs

@@ -12,7 +12,7 @@ IHostInformationProvider host
     private readonly TimeSpan _accessTokenDuration = TimeSpan.FromHours(2);
     private readonly TimeSpan _refreshTokenDuration = TimeSpan.FromDays(7);
 
-    public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, CancellationToken cancellation = default)
+    public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, IEnumerable<Audience> audiences, CancellationToken cancellation = default)
     {
         var filters = GroupFilters.WithSpecifications()
             .WithRealmId(user.RealmId)
@@ -31,6 +31,12 @@ public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, Can
             .ToList();
 
         var tokenHandler = new JwtSecurityTokenHandler();
+        var resolvedAudiences = audiences
+            .Where(audience => !string.IsNullOrWhiteSpace(audience.Value))
+            .Select(audience => audience.Value.Trim())
+            .Distinct(StringComparer.Ordinal)
+            .ToList();
+
         var claims = new ClaimsBuilder()
             .WithSubject(user.Id.ToString())
             .WithUsername(user.Username)
@@ -43,10 +49,15 @@ public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, Can
         claims.WithClaim(IdentityClaimNames.Realm, realm.Name);
         claims.WithClaim(IdentityClaimNames.RealmId, realm.Id);
 
+        if (resolvedAudiences.Count > 0)
+        {
+            claims.WithAudiences(resolvedAudiences);
+        }
+
         var claimsIdentity = new ClaimsIdentity(claims.Build());
         var tokenDescriptor = new SecurityTokenDescriptor
         {
-            Audience = realm.Name,
+            Audience = resolvedAudiences.Count > 0 ? null : realm.Name,
             Subject = claimsIdentity,
             Issuer = host.Address.ToString().TrimEnd('/'),
             SigningCredentials = credentials,
@@ -66,6 +77,9 @@ public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, Can
         return Result<SecurityToken>.Success(securityToken);
     }
 
+    public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, CancellationToken cancellation = default)
+        => await GenerateAccessTokenAsync(user, [], cancellation);
+
     public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(Client client, CancellationToken cancellation = default)
     {
         var tokenHandler = new JwtSecurityTokenHandler();

Applications/Backend/Source/HttpsRichardy.Federation.Infrastructure/Usings.cs

@@ -10,6 +10,7 @@
 
 global using HttpsRichardy.Federation.Domain.Aggregates;
 global using HttpsRichardy.Federation.Domain.Errors;
+global using HttpsRichardy.Federation.Domain.Concepts;
 global using HttpsRichardy.Federation.Domain.Collections;
 global using HttpsRichardy.Federation.Domain.Filtering;
 global using HttpsRichardy.Federation.Domain.Filtering.Builders;

Applications/Backend/Source/HttpsRichardy.Federation.WebApi/Pages/Authorize.cshtml.cs

@@ -121,6 +121,7 @@ public async Task<IActionResult> OnPostAsync()
         var code = Guid.NewGuid().ToString("N").ToUpperInvariant();
         var metadata = new Dictionary<string, string>
         {
+            { "client.id", Parameters.ClientId ?? string.Empty },
             { "code.challenge", Parameters.CodeChallenge ?? string.Empty },
             { "code.challenge.method", Parameters.CodeChallengeMethod ?? string.Empty }
         };

Applications/Backend/Tests/Integration/Endpoints/ConnectEndpointTests.cs

@@ -284,6 +284,12 @@ public async Task WhenPostTokenWithValidAuthorizationCode_ShouldReturnAccessToke
         Assert.NotEmpty(clients);
         Assert.NotNull(client);
 
+        // arrange: assign client audience
+        var assignAudience = new AssignClientAudienceScheme { Value = "backend.api" };
+        var assignAudienceResponse = await realmAdminClient.PostAsJsonAsync($"api/v1/clients/{client.Id}/audiences", assignAudience);
+
+        Assert.Equal(HttpStatusCode.OK, assignAudienceResponse.StatusCode);
+
         // arrange: create user for realm
         var credentials = new IdentityEnrollmentCredentials
         {
@@ -341,6 +347,7 @@ public async Task WhenPostTokenWithValidAuthorizationCode_ShouldReturnAccessToke
             ExpiresAt = DateTime.UtcNow.AddMinutes(5),
             Metadata = new Dictionary<string, string>
             {
+                ["client.id"] = client.ClientId,
                 ["code.challenge"] = codeChallenge,
                 ["code.challenge.method"] = codeChallengeMethod
             }
@@ -367,5 +374,15 @@ public async Task WhenPostTokenWithValidAuthorizationCode_ShouldReturnAccessToke
         // assert: response should be 200 OK
         Assert.Equal(HttpStatusCode.OK, response.StatusCode);
         Assert.NotNull(grant);
+
+        var handler = new JwtSecurityTokenHandler();
+        var jwt = handler.ReadJwtToken(grant.AccessToken);
+        var audiences = jwt.Claims
+            .Where(claim => claim.Type == JwtRegisteredClaimNames.Aud)
+            .Select(claim => claim.Value)
+            .ToList();
+
+        Assert.Contains("backend.api", audiences);
+        Assert.DoesNotContain(realm.Name, audiences);
     }
 }

Applications/Backend/Tests/Integration/Security/JwtSecurityTokenServiceTests.cs

@@ -98,6 +98,43 @@ public async Task WhenGeneratingAccessToken_ThenItMustBeValidAndContainCorrectCl
         }
     }
 
+    [Fact(DisplayName = "[infrastructure] - when generating user access token with provided audiences, then token should include only provided audiences")]
+    public async Task WhenGeneratingUserAccessTokenWithProvidedAudiences_ThenShouldIncludeOnlyProvidedAudiences()
+    {
+        /* arrange: create a user and configure realm */
+        var user = _fixture.Create<User>();
+        var realm = _fixture.Create<Realm>();
+
+        _realmProvider.Setup(provider => provider.GetCurrentRealm())
+            .Returns(realm);
+
+        var allowedAudiences = new[]
+        {
+            new Audience("backend.api"),
+            new Audience("orders.api"),
+            new Audience("backend.api")
+        };
+
+        /* act: generate an access token with explicit audiences */
+        var result = await _jwtSecurityTokenService.GenerateAccessTokenAsync(user, allowedAudiences);
+
+        /* assert: token must be successful and valid */
+        Assert.True(result.IsSuccess);
+        Assert.NotNull(result.Data);
+
+        var handler = new JwtSecurityTokenHandler();
+        var jwtToken = handler.ReadJwtToken(result.Data.Value);
+
+        var audiences = jwtToken.Claims
+            .Where(claim => claim.Type == JwtRegisteredClaimNames.Aud)
+            .Select(claim => claim.Value)
+            .ToList();
+
+        Assert.Contains("backend.api", audiences);
+        Assert.Contains("orders.api", audiences);
+        Assert.Equal(2, audiences.Distinct(StringComparer.Ordinal).Count());
+    }
+
     [Fact(DisplayName = "[infrastructure] - when generating a refresh token, then it must be valid and contain correct claims and be persisted")]
     public async Task WhenGeneratingRefreshToken_ThenItMustBeValidAndContainCorrectClaimsAndBePersisted()
     {

CHANGELOG

@@ -1,3 +1,9 @@
+# 4.2.1 - 2026-04-25
+
+this patch fixes an issue in the authorization_code flow where the access token issued for an authenticated user did not include the allowed audiences configured on the requesting client. this created a mismatch between the client context that initiated authorization and the resulting user token.
+
+starting in 4.2.1, when a client obtains an authorization code and exchanges it for an access token, the generated user access token now includes all allowed audiences configured for that client. in the same flow, the authorization code is also bound to the client context to ensure exchange consistency.
+
 # 4.2.0 - 2026-04-24
 
 this release introduces a fluent builder api to the sdk, making it more intuitive and expressive to construct filter parameters for client calls. previously, using parameter models required manual object initialization and explicit property assignment, which could become verbose as the number of filters grew. with the new fluent approach, developers can chain builder methods in a readable and intention-driven way, improving both usability and discoverability of the api.

README.md

@@ -67,7 +67,7 @@ You can pull either:
 
 ```bash
 docker pull httpsrichardy/federation:latest
-docker pull httpsrichardy/federation:4.1.0
+docker pull httpsrichardy/federation:4.2.1
 ```
 
 To run the container, provide the required environment variables for database and administration bootstrap: