Handle empty JSON responses

acme4j-client/src/main/java/org/shredzone/acme4j/Account.java

@@ -158,7 +158,10 @@ public class Account extends AcmeJsonResource {
             conn.sendSignedRequest(newAuthzUrl, claims, getLogin());
 
             Authorization auth = getLogin().bindAuthorization(conn.getLocation());
-            auth.setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                auth.setJSON(json);
+            }
             return auth;
         }
     }
@@ -224,7 +227,10 @@ public class Account extends AcmeJsonResource {
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
 
-            setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                setJSON(json);
+            }
         }
     }
 
@@ -294,7 +300,10 @@ public class Account extends AcmeJsonResource {
 
                 conn.sendSignedRequest(getLocation(), claims, getLogin());
 
-                setJSON(conn.readJsonResponse());
+                JSON json = conn.readJsonResponse();
+                if (json != null) {
+                    setJSON(json);
+                }
             }
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/AccountBuilder.java

@@ -35,6 +35,7 @@ import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.connector.Resource;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.toolbox.AcmeUtils;
+import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -210,7 +211,10 @@ public class AccountBuilder {
             URL location = conn.getLocation();
 
             Login login = new Login(location, keyPair, session);
-            login.getAccount().setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                login.getAccount().setJSON(json);
+            }
             return login;
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java

@@ -132,7 +132,10 @@ public class Authorization extends AcmeJsonResource {
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
 
-            setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                setJSON(json);
+            }
         }
     }
 

acme4j-client/src/main/java/org/shredzone/acme4j/OrderBuilder.java

@@ -25,6 +25,7 @@ import java.util.Set;
 import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.connector.Resource;
 import org.shredzone.acme4j.exception.AcmeException;
+import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -152,7 +153,10 @@ public class OrderBuilder {
             conn.sendSignedRequest(session.resourceUrl(Resource.NEW_ORDER), claims, login);
 
             Order order = new Order(login, conn.getLocation());
-            order.setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                order.setJSON(json);
+            }
             return order;
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java

@@ -145,7 +145,10 @@ public class Challenge extends AcmeJsonResource {
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
 
-            setJSON(conn.readJsonResponse());
+            JSON json = conn.readJsonResponse();
+            if (json != null) {
+                setJSON(json);
+            }
         }
     }
 

acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java

@@ -94,7 +94,7 @@ public interface Connection extends AutoCloseable {
     /**
      * Reads a server response as JSON data.
      *
-     * @return The JSON response
+     * @return The JSON response, or {@code null} if the server did not provide any data.
      */
     JSON readJsonResponse() throws AcmeException;
 

acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java

@@ -192,6 +192,10 @@ public class DefaultConnection implements Connection {
     public JSON readJsonResponse() throws AcmeException {
         assertConnectionIsOpen();
 
+        if (conn.getContentLength() == 0) {
+            return null;
+        }
+
         String contentType = AcmeUtils.getContentType(conn.getHeaderField(CONTENT_TYPE_HEADER));
         if (!("application/json".equals(contentType)
                     || "application/problem+json".equals(contentType))) {

acme4j-client/src/test/java/org/shredzone/acme4j/connector/DefaultConnectionTest.java

@@ -427,6 +427,7 @@ public class DefaultConnectionTest {
         String jsonData = "{\"type\":\"urn:ietf:params:acme:error:unauthorized\",\"detail\":\"Invalid response: 404\"}";
 
         when(mockUrlConnection.getHeaderField("Content-Type")).thenReturn("application/problem+json");
+        when(mockUrlConnection.getContentLength()).thenReturn(jsonData.length());
         when(mockUrlConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_FORBIDDEN);
         when(mockUrlConnection.getOutputStream()).thenReturn(new ByteArrayOutputStream());
         when(mockUrlConnection.getErrorStream()).thenReturn(new ByteArrayInputStream(jsonData.getBytes("utf-8")));
@@ -446,6 +447,7 @@ public class DefaultConnectionTest {
 
         verify(mockUrlConnection, atLeastOnce()).getHeaderField("Content-Type");
         verify(mockUrlConnection, atLeastOnce()).getResponseCode();
+        verify(mockUrlConnection).getContentLength();
         verify(mockUrlConnection).getErrorStream();
         verify(mockUrlConnection).getURL();
     }
@@ -461,6 +463,7 @@ public class DefaultConnectionTest {
         linkHeader.put("Link", Arrays.asList("<https://example.com/tos.pdf>; rel=\"terms-of-service\""));
 
         when(mockUrlConnection.getHeaderField("Content-Type")).thenReturn("application/problem+json");
+        when(mockUrlConnection.getContentLength()).thenReturn(jsonData.length());
         when(mockUrlConnection.getHeaderFields()).thenReturn(linkHeader);
         when(mockUrlConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_FORBIDDEN);
         when(mockUrlConnection.getOutputStream()).thenReturn(new ByteArrayOutputStream());
@@ -484,6 +487,7 @@ public class DefaultConnectionTest {
         verify(mockUrlConnection, atLeastOnce()).getHeaderFields();
         verify(mockUrlConnection, atLeastOnce()).getResponseCode();
         verify(mockUrlConnection).getErrorStream();
+        verify(mockUrlConnection).getContentLength();
         verify(mockUrlConnection, atLeastOnce()).getURL();
     }
 
@@ -500,6 +504,7 @@ public class DefaultConnectionTest {
         Instant retryAfter = Instant.now().plusSeconds(30L).truncatedTo(ChronoUnit.MILLIS);
 
         when(mockUrlConnection.getHeaderField("Content-Type")).thenReturn("application/problem+json");
+        when(mockUrlConnection.getContentLength()).thenReturn(jsonData.length());
         when(mockUrlConnection.getHeaderField("Retry-After")).thenReturn(retryAfter.toString());
         when(mockUrlConnection.getHeaderFieldDate("Retry-After", 0L)).thenReturn(retryAfter.toEpochMilli());
         when(mockUrlConnection.getHeaderFields()).thenReturn(linkHeader);
@@ -529,6 +534,7 @@ public class DefaultConnectionTest {
         verify(mockUrlConnection).getHeaderFieldDate("Retry-After", 0L);
         verify(mockUrlConnection, atLeastOnce()).getHeaderFields();
         verify(mockUrlConnection, atLeastOnce()).getResponseCode();
+        verify(mockUrlConnection).getContentLength();
         verify(mockUrlConnection).getErrorStream();
         verify(mockUrlConnection, atLeastOnce()).getURL();
     }
@@ -833,6 +839,7 @@ public class DefaultConnectionTest {
         String jsonData = "{\n\"foo\":123,\n\"bar\":\"a-string\"\n}\n";
 
         when(mockUrlConnection.getHeaderField("Content-Type")).thenReturn("application/json");
+        when(mockUrlConnection.getContentLength()).thenReturn(jsonData.length());
         when(mockUrlConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_OK);
         when(mockUrlConnection.getInputStream()).thenReturn(new ByteArrayInputStream(jsonData.getBytes("utf-8")));
 
@@ -845,6 +852,7 @@ public class DefaultConnectionTest {
         }
 
         verify(mockUrlConnection).getHeaderField("Content-Type");
+        verify(mockUrlConnection).getContentLength();
         verify(mockUrlConnection).getResponseCode();
         verify(mockUrlConnection).getInputStream();
         verifyNoMoreInteractions(mockUrlConnection);