Added support for Back Channel Login

src/main/java/com/auth0/client/auth/AuthAPI.java

@@ -225,6 +225,61 @@ public AuthorizeUrlBuilder authorizeUrl(String redirectUri) {
         return AuthorizeUrlBuilder.newInstance(baseUrl, clientId, redirectUri);
     }
 
+    public Request<BackChannelAuthorizeResponse> authorizeBackChannel(String scope, String bindingMessage, Map<String, Object> loginHint) {
+        return authorizeBackChannel(scope, bindingMessage, loginHint, null, null);
+    }
+
+    public Request<BackChannelAuthorizeResponse> authorizeBackChannel(String scope, String bindingMessage, Map<String, Object> loginHint, String audience, Integer requestExpiry) {
+        Asserts.assertNotNull(scope, "scope");
+        Asserts.assertNotNull(bindingMessage, "binding message");
+        Asserts.assertNotNull(loginHint, "login hint");
+
+        String url = baseUrl
+            .newBuilder()
+            .addPathSegment("bc-authorize")
+            .build()
+            .toString();
+
+        FormBodyRequest<BackChannelAuthorizeResponse> request = new FormBodyRequest<>(client, null, url, HttpMethod.POST, new TypeReference<BackChannelAuthorizeResponse>() {});
+
+        request.addParameter(KEY_CLIENT_ID, clientId);
+        addClientAuthentication(request, false);
+        request.addParameter("scope", scope);
+        request.addParameter("binding_message", bindingMessage);
+
+        if(Objects.nonNull(audience)){
+            request.addParameter(KEY_AUDIENCE, audience);
+        }
+        if(Objects.nonNull(requestExpiry)){
+            request.addParameter("request_expiry", requestExpiry);
+        }
+
+        try {
+            String loginHintJson = getMapper().writeValueAsString(loginHint);
+            request.addParameter("login_hint", loginHintJson);
+        }
+        catch (JsonProcessingException e) {
+            throw new IllegalArgumentException("'loginHint' must be a map that can be serialized to JSON", e);
+        }
+        return request;
+    }
+
+    public Request<BackChannelTokenResponse> getBackChannelLoginStatus(String authReqId, String grantType) {
+        Asserts.assertNotNull(authReqId, "auth req id");
+        Asserts.assertNotNull(grantType, "grant type");
+
+        String url = getTokenUrl();
+
+        FormBodyRequest<BackChannelTokenResponse> request = new FormBodyRequest<>(client, null, url, HttpMethod.POST, new TypeReference<BackChannelTokenResponse>() {});
+
+        request.addParameter(KEY_CLIENT_ID, clientId);
+        addClientAuthentication(request, false);
+        request.addParameter("auth_req_id", authReqId);
+        request.addParameter(KEY_GRANT_TYPE, grantType);
+
+        return request;
+    }
+
     /**
      * Builds an authorization URL for Pushed Authorization Requests (PAR)
      * @param requestUri the {@code request_uri} parameter from a successful pushed authorization request.

src/main/java/com/auth0/json/auth/BackChannelAuthorizeResponse.java

@@ -0,0 +1,45 @@
+package com.auth0.json.auth;
+
+import com.fasterxml.jackson.annotation.*;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class BackChannelAuthorizeResponse {
+    @JsonProperty("auth_req_id")
+    private String authReqId;
+    @JsonProperty("expires_in")
+    private Long expiresIn;
+    @JsonProperty("interval")
+    private Integer interval;
+
+    @JsonCreator
+    public BackChannelAuthorizeResponse(@JsonProperty("auth_req_id") String authReqId, @JsonProperty("expires_in") Long expiresIn, @JsonProperty("interval") Integer interval) {
+        this.authReqId = authReqId;
+        this.expiresIn = expiresIn;
+        this.interval = interval;
+    }
+
+    /**
+     * Getter for the Auth Request ID.
+     * @return the Auth Request ID.
+     */
+    public String getAuthReqId() {
+        return authReqId;
+    }
+
+    /**
+     * Getter for the Expires In value.
+     * @return the Expires In value.
+     */
+    public Long getExpiresIn() {
+        return expiresIn;
+    }
+
+    /**
+     * Getter for the Interval value.
+     * @return the Interval value.
+     */
+    public Integer getInterval() {
+        return interval;
+    }
+}

src/main/java/com/auth0/json/auth/BackChannelTokenResponse.java

@@ -0,0 +1,34 @@
+package com.auth0.json.auth;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class BackChannelTokenResponse {
+    @JsonProperty("access_token")
+    private String accessToken;
+    @JsonProperty("id_token")
+    private String idToken;
+    @JsonProperty("expires_in")
+    private long expiresIn;
+    @JsonProperty("scope")
+    private String scope;
+
+    public String getAccessToken() {
+        return accessToken;
+    }
+
+    public String getIdToken() {
+        return idToken;
+    }
+
+    public long getExpiresIn() {
+        return expiresIn;
+    }
+
+    public String getScope() {
+        return scope;
+    }
+}

src/test/java/com/auth0/client/MockServer.java

@@ -116,6 +116,8 @@ public class MockServer {
     public static final String PASSWORDLESS_EMAIL_RESPONSE = "src/test/resources/auth/passwordless_email.json";
     public static final String PASSWORDLESS_SMS_RESPONSE = "src/test/resources/auth/passwordless_sms.json";
     public static final String PUSHED_AUTHORIZATION_RESPONSE = "src/test/resources/auth/pushed_authorization_response.json";
+    public static final String BACK_CHANNEL_AUTHORIZE_RESPONSE = "src/test/resources/auth/back_channel_authorize_response.json";
+    public static final String BACK_CHANNEL_LOGIN_STATUS_RESPONSE = "src/test/resources/auth/back_channel_login_status_response.json";
     public static final String AUTHENTICATOR_METHOD_BY_ID = "src/test/resources/mgmt/authenticator_method_by_id.json";
     public static final String AUTHENTICATOR_METHOD_CREATE = "src/test/resources/mgmt/authenticator_method_create.json";
     public static final String AUTHENTICATOR_METHOD_LIST = "src/test/resources/mgmt/authenticator_method_list.json";

src/test/java/com/auth0/client/auth/AuthAPITest.java

@@ -2009,6 +2009,127 @@ public void shouldThrowWhenCreatePushedAuthorizationJarRequestWithInvalidAuthDet
         assertThat(e.getCause(), instanceOf(JsonProcessingException.class));
     }
 
+    @Test
+    public void authorizeBackChannelWhenScopeIsNull() {
+        verifyThrows(IllegalArgumentException.class,
+            () -> api.authorizeBackChannel(null, "This is binding message", getLoginHint()),
+            "'scope' cannot be null!");
+    }
+
+    @Test
+    public void authorizeBackChannelWhenBindingMessageIsNull() {
+        verifyThrows(IllegalArgumentException.class,
+            () -> api.authorizeBackChannel("openid", null, getLoginHint()),
+            "'binding message' cannot be null!");
+    }
+
+    @Test
+    public void authorizeBackChannelWhenLoginHintIsNull() {
+        verifyThrows(IllegalArgumentException.class,
+            () -> api.authorizeBackChannel("openid", "This is binding message", null),
+            "'login hint' cannot be null!");
+    }
+
+    @Test
+    public void authorizeBackChannel() throws Exception {
+        Request<BackChannelAuthorizeResponse> request = api.authorizeBackChannel("openid", "This is binding message", getLoginHint());
+        assertThat(request, is(notNullValue()));
+
+        server.jsonResponse(BACK_CHANNEL_AUTHORIZE_RESPONSE, 200);
+        BackChannelAuthorizeResponse response = request.execute().getBody();
+        RecordedRequest recordedRequest = server.takeRequest();
+
+        assertThat(recordedRequest, hasMethodAndPath(HttpMethod.POST, "/bc-authorize"));
+        assertThat(recordedRequest, hasHeader("Content-Type", "application/x-www-form-urlencoded"));
+
+        String body = URLDecoder.decode(readFromRequest(recordedRequest), StandardCharsets.UTF_8.name());
+        assertThat(body, containsString("scope=" + "openid"));
+        assertThat(body, containsString("client_id=" + CLIENT_ID));
+        assertThat(body, containsString("client_secret=" + CLIENT_SECRET));
+        assertThat(body, containsString("binding_message=This is binding message"));
+        assertThat(body, containsString("login_hint={\"sub\":\"auth0|user1\",\"format\":\"format1\",\"iss\":\"https://auth0.com\"}"));
+
+        assertThat(response, is(notNullValue()));
+        assertThat(response.getAuthReqId(), not(emptyOrNullString()));
+        assertThat(response.getExpiresIn(), notNullValue());
+        assertThat(response.getInterval(), notNullValue());
+    }
+
+    @Test
+    public void authorizeBackChannelWithAudienceAndRequestExpiry() throws Exception {
+        Request<BackChannelAuthorizeResponse> request = api.authorizeBackChannel("openid", "This is binding message", getLoginHint(), "https://api.example.com", 300);
+        assertThat(request, is(notNullValue()));
+
+        server.jsonResponse(BACK_CHANNEL_AUTHORIZE_RESPONSE, 200);
+        BackChannelAuthorizeResponse response = request.execute().getBody();
+        RecordedRequest recordedRequest = server.takeRequest();
+
+        assertThat(recordedRequest, hasMethodAndPath(HttpMethod.POST, "/bc-authorize"));
+        assertThat(recordedRequest, hasHeader("Content-Type", "application/x-www-form-urlencoded"));
+
+        String body = URLDecoder.decode(readFromRequest(recordedRequest), StandardCharsets.UTF_8.name());
+        assertThat(body, containsString("scope=" + "openid"));
+        assertThat(body, containsString("client_id=" + CLIENT_ID));
+        assertThat(body, containsString("client_secret=" + CLIENT_SECRET));
+        assertThat(body, containsString("binding_message=This is binding message"));
+        assertThat(body, containsString("login_hint={\"sub\":\"auth0|user1\",\"format\":\"format1\",\"iss\":\"https://auth0.com\"}"));
+        assertThat(body, containsString("request_expiry=" + 300));
+        assertThat(body, containsString("audience=" + "https://api.example.com"));
+
+        assertThat(response, is(notNullValue()));
+        assertThat(response.getAuthReqId(), not(emptyOrNullString()));
+        assertThat(response.getExpiresIn(), notNullValue());
+        assertThat(response.getInterval(), notNullValue());
+    }
+
+    private Map<String, Object> getLoginHint() {
+        Map<String, Object> loginHint = new HashMap<>();
+        loginHint.put("format", "format1");
+        loginHint.put("iss", "https://auth0.com");
+        loginHint.put("sub", "auth0|user1");
+        return  loginHint;
+    }
+
+    @Test
+    public void getBackChannelLoginStatusWhenAuthReqIdIsNull() {
+        verifyThrows(IllegalArgumentException.class,
+            () -> api.getBackChannelLoginStatus(null, "ciba"),
+            "'auth req id' cannot be null!");
+    }
+
+    @Test
+    public void getBackChannelLoginStatusWhenGrantTypeIsNull() {
+        verifyThrows(IllegalArgumentException.class,
+            () -> api.getBackChannelLoginStatus("red_id_1", null),
+            "'grant type' cannot be null!");
+    }
+
+    @Test
+    public void getBackChannelLoginStatus() throws Exception {
+        Request<BackChannelTokenResponse> request = api.getBackChannelLoginStatus("red_id_1", "ciba");
+        assertThat(request, is(notNullValue()));
+
+        server.jsonResponse(BACK_CHANNEL_LOGIN_STATUS_RESPONSE, 200);
+        BackChannelTokenResponse response = request.execute().getBody();
+        RecordedRequest recordedRequest = server.takeRequest();
+
+        assertThat(recordedRequest, hasMethodAndPath(HttpMethod.POST, "/oauth/token"));
+        assertThat(recordedRequest, hasHeader("Content-Type", "application/x-www-form-urlencoded"));
+
+        String body = URLDecoder.decode(readFromRequest(recordedRequest), StandardCharsets.UTF_8.name());
+        assertThat(body, containsString("client_id=" + CLIENT_ID));
+        assertThat(body, containsString("client_secret=" + CLIENT_SECRET));
+        assertThat(body, containsString("auth_req_id=red_id_1"));
+        assertThat(body, containsString("grant_type=ciba"));
+
+        assertThat(response, is(notNullValue()));
+        assertThat(response.getAccessToken(), not(emptyOrNullString()));
+        assertThat(response.getIdToken(), not(emptyOrNullString()));
+        assertThat(response.getExpiresIn(), notNullValue());
+        assertThat(response.getScope(), not(emptyOrNullString()));
+    }
+
+
     private Map<String, String> getQueryMap(String input) {
         String[] params = input.split("&");
 

src/test/resources/auth/back_channel_authorize_response.json

@@ -0,0 +1,5 @@
+{
+  "auth_req_id": "red_id_1",
+  "expires_in": 300,
+  "interval": 5
+}

src/test/resources/auth/back_channel_login_status_response.json

@@ -0,0 +1,6 @@
+{
+  "access_token": "eyJhbGciOiJkaXIi.....",
+  "id_token": "eyJhbGciOiJSUzI1NiIs.....",
+  "expires_in": 86400,
+  "scope": "openid"
+}