feat: reject the consent request when the user denies access

README.md

@@ -357,7 +357,7 @@ instead, use a Gradle composite build:
 - [ ] Add a fancier UI
 - [ ] Refactor controller/service logic to be more consistent
 - [ ] Tests to mock Ory Hydra responses
-- [ ] Allow rejecting on consent screen
+- [x] Allow rejecting on consent screen
 - [ ] Add more unit tests
 - [ ] Document playwright usage
 - [ ] Show login errors on login screen

reference-app/src/main/java/com/ardetrick/oryhydrareference/consent/ConsentForm.java

@@ -4,7 +4,7 @@
 
 /** The Java object representing the data submitted by the form in consent.ftlh. */
 public record ConsentForm(
-    String submit, String consentChallenge, Boolean remember, List<String> scopes) {
+    String consentChallenge, Boolean remember, List<String> scopes, String deny) {
 
   /**
    * This field is implemented in HTML as a checkbox. When a checkbox element is not checked in a
@@ -16,4 +16,12 @@ public boolean isRemember() {
     }
     return remember;
   }
+
+  /**
+   * The form has two submit buttons and only the one actually clicked is included in the form post,
+   * so this field is non-null exactly when the user clicked "Deny access".
+   */
+  public boolean isDenied() {
+    return deny != null;
+  }
 }

reference-app/src/main/java/com/ardetrick/oryhydrareference/consent/ConsentModelAndViewMapper.java

@@ -1,6 +1,7 @@
 package com.ardetrick.oryhydrareference.consent;
 
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.Accepted;
+import com.ardetrick.oryhydrareference.consent.ConsentResponse.Denied;
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.DisplayUI;
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.Skip;
 import com.ardetrick.oryhydrareference.modelandview.ModelAndViewUtils;
@@ -14,6 +15,7 @@ public static ModelAndView map(@NonNull final ConsentResponse response) {
       case Skip r -> handleSkip(r);
       case DisplayUI r -> handleDisplayUI(r);
       case Accepted r -> handleAccepted(r);
+      case Denied r -> handleDenied(r);
     };
   }
 
@@ -30,4 +32,9 @@ private static ModelAndView handleDisplayUI(DisplayUI displayUI) {
   private static ModelAndView handleAccepted(Accepted accepted) {
     return ModelAndViewUtils.redirectToDifferentContext(accepted.redirectTo());
   }
+
+  // Hydra's redirect carries the OAuth error (error=access_denied&...) back to the client.
+  private static ModelAndView handleDenied(Denied denied) {
+    return ModelAndViewUtils.redirectToDifferentContext(denied.redirectTo());
+  }
 }

reference-app/src/main/java/com/ardetrick/oryhydrareference/consent/ConsentResponse.java

@@ -3,12 +3,17 @@
 import java.util.List;
 
 public sealed interface ConsentResponse
-    permits ConsentResponse.Accepted, ConsentResponse.DisplayUI, ConsentResponse.Skip {
+    permits ConsentResponse.Accepted,
+        ConsentResponse.Denied,
+        ConsentResponse.DisplayUI,
+        ConsentResponse.Skip {
 
   record Skip(String redirectTo) implements ConsentResponse {}
 
   record DisplayUI(List<String> requestedScopes, String consentChallenge)
       implements ConsentResponse {}
 
   record Accepted(String redirectTo) implements ConsentResponse {}
+
+  record Denied(String redirectTo) implements ConsentResponse {}
 }

reference-app/src/main/java/com/ardetrick/oryhydrareference/consent/ConsentService.java

@@ -1,10 +1,12 @@
 package com.ardetrick.oryhydrareference.consent;
 
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.Accepted;
+import com.ardetrick.oryhydrareference.consent.ConsentResponse.Denied;
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.DisplayUI;
 import com.ardetrick.oryhydrareference.consent.ConsentResponse.Skip;
 import com.ardetrick.oryhydrareference.hydra.AcceptConsentRequest;
 import com.ardetrick.oryhydrareference.hydra.HydraAdminClient;
+import com.ardetrick.oryhydrareference.hydra.RejectConsentRequest;
 import lombok.AccessLevel;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
@@ -40,6 +42,17 @@ public ConsentResponse processInitialConsentRequest(@NonNull final String consen
   public ConsentResponse processConsentForm(@NonNull final ConsentForm consentForm) {
     val consentChallenge = consentForm.consentChallenge();
 
+    if (consentForm.isDenied()) {
+      val rejectConsentRequest =
+          RejectConsentRequest.builder()
+              .consentChallenge(consentChallenge)
+              .error("access_denied")
+              .errorDescription("user denied access")
+              .build();
+      val rejectConsentResponse = hydraAdminClient.rejectConsentRequest(rejectConsentRequest);
+      return new Denied(rejectConsentResponse.getRedirectTo());
+    }
+
     val consentRequest = hydraAdminClient.getConsentRequest(consentChallenge);
 
     val acceptConsentRequest =

reference-app/src/main/java/com/ardetrick/oryhydrareference/hydra/HydraAdminClient.java

@@ -101,6 +101,20 @@ public OAuth2RedirectTo acceptConsentRequest(@NonNull AcceptConsentRequest accep
     }
   }
 
+  public OAuth2RedirectTo rejectConsentRequest(@NonNull RejectConsentRequest rejectConsentRequest) {
+    val rejectOAuth2Request = OryHydraRequestMapper.map(rejectConsentRequest);
+
+    try {
+      return oAuth2Api()
+          .rejectOAuth2ConsentRequest(rejectConsentRequest.consentChallenge(), rejectOAuth2Request);
+    } catch (ApiException e) {
+      switch (e.getCode()) {
+        case 404, 500 -> throw new RuntimeException("code: " + e.getCode(), e); // jsonError
+        default -> throw new RuntimeException("unhandled code: " + e.getCode(), e);
+      }
+    }
+  }
+
   @Data
   @org.springframework.context.annotation.Configuration
   @ConfigurationProperties("reference-app.hydra")

reference-app/src/main/java/com/ardetrick/oryhydrareference/hydra/OryHydraRequestMapper.java

@@ -3,6 +3,7 @@
 import lombok.NonNull;
 import sh.ory.hydra.model.AcceptOAuth2ConsentRequest;
 import sh.ory.hydra.model.AcceptOAuth2ConsentRequestSession;
+import sh.ory.hydra.model.RejectOAuth2Request;
 
 public class OryHydraRequestMapper {
 
@@ -18,6 +19,12 @@ public static AcceptOAuth2ConsentRequest map(
         .session(getAcceptOAuth2ConsentRequestSession());
   }
 
+  public static RejectOAuth2Request map(@NonNull final RejectConsentRequest rejectConsentRequest) {
+    return new RejectOAuth2Request()
+        .error(rejectConsentRequest.error())
+        .errorDescription(rejectConsentRequest.errorDescription());
+  }
+
   private static AcceptOAuth2ConsentRequestSession getAcceptOAuth2ConsentRequestSession() {
     // An example of setting custom claims.
     record ExampleCustomClaims(String exampleCustomClaimKey) {}

reference-app/src/main/java/com/ardetrick/oryhydrareference/hydra/RejectConsentRequest.java

@@ -0,0 +1,8 @@
+package com.ardetrick.oryhydrareference.hydra;
+
+import lombok.Builder;
+import lombok.NonNull;
+
+@Builder
+public record RejectConsentRequest(
+    @NonNull String consentChallenge, @NonNull String error, String errorDescription) {}

reference-app/src/main/resources/templates/consent.ftlh

@@ -18,8 +18,8 @@
   <label for="remember">Remember me:</label>
   <input type="checkbox" id="remember" name="remember" checked /><br>
 
-  <input type="submit" id="accept" name="submit" value="Allow access" />
-  <input type="submit" id="reject" name="submit" value="Deny access" />
+  <input type="submit" id="accept" name="accept" value="Allow access" />
+  <input type="submit" id="reject" name="deny" value="Deny access" />
 </form>
 </body>
 </html>

reference-app/src/test/java/com/ardetrick/oryhydrareference/OryHydraReferenceApplicationFunctionalTests.java

@@ -367,10 +367,13 @@ public void skipConsentScreenOnSecondLoginWhenRememberMeIsUsed() {
     assertThat(page.url()).contains("/client/callback?code=");
   }
 
-  private String getCodeFromCallbackCaptor() {
+  private String getCallbackQueryString() {
     verify(queryStringConsumer).accept(queryStringConsumerArgumentCaptor.capture());
-    val queryStringValue = queryStringConsumerArgumentCaptor.getValue();
-    return Arrays.stream(queryStringValue.split("&"))
+    return queryStringConsumerArgumentCaptor.getValue();
+  }
+
+  private String getCodeFromCallbackCaptor() {
+    return Arrays.stream(getCallbackQueryString().split("&"))
         .filter(queryStringParam -> queryStringParam.startsWith("code="))
         .findFirst()
         .map(queryStringParam -> queryStringParam.replace("code=", ""))
@@ -429,6 +432,39 @@ public void doNotSkipConsentScreenOnSecondLoginWhenRememberMeIsFalse() {
     // Consent screen is not skipped
     assertThat(page.url()).contains("/consent");
   }
+
+  @Test
+  public void denyConsentRedirectsToClientWithAccessDeniedError() {
+    val screenshotPathProducer =
+        ScreenshotPathProducer.builder()
+            .testName("denyConsentRedirectsToClientWithAccessDeniedError")
+            .build();
+
+    val page = browser.newPage();
+
+    page.navigate(getUriToInitiateFlow().toString());
+    page.screenshot(screenshotPathProducer.screenshotOptionsForStepName("initial-load"));
+
+    page.locator("input[name=loginEmail]").fill("foo@bar.com");
+    page.locator("input[name=loginPassword]").fill("password");
+
+    page.locator("input[name=submit]").click();
+
+    page.waitForLoadState();
+    page.screenshot(screenshotPathProducer.screenshotOptionsForStepName("after-login-submit"));
+
+    page.locator("input[id=reject]").click();
+
+    page.waitForLoadState();
+    page.screenshot(screenshotPathProducer.screenshotOptionsForStepName("after-consent-deny"));
+
+    // The browser lands on the client's callback carrying a real OAuth error instead of a code.
+    assertThat(page.url()).contains("/client/callback?error=access_denied");
+
+    val queryString = getCallbackQueryString();
+    assertThat(queryString).contains("error=access_denied");
+    assertThat(queryString).doesNotContain("code=");
+  }
 }
 
 @JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)