Fix Deserialization error when "extensions" contains "extra" field (#10)

* use custom deserialization to handle list extensions

* Fix parsing error when extensions contain "extra" field

Co-authored-by: Joshua Hight <joshua.hight@doordash.com>
Co-authored-by: Martin Wilhelm <martin.wilhelm@essendi.de>

Author: 3 people

.gitignore

@@ -1,5 +1,6 @@
 #Intellij's dirty laundry
 .idea/*
+*.iml
 
 #maven build artifcts
 target/*

src/io/calidog/certstream/CertStream.java

@@ -1,6 +1,7 @@
 package io.calidog.certstream;
 
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import com.google.gson.JsonSyntaxException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -60,13 +61,13 @@ public static void onMessage(CertStreamMessageHandler handler)
             CertStreamMessagePOJO msg;
             try
             {
-                msg = new Gson().fromJson(string, CertStreamMessagePOJO.class);
+                msg = certStreamGson.fromJson(string, CertStreamMessagePOJO.class);
 
                 if (msg.messageType.equalsIgnoreCase("heartbeat"))
                 {
                     return;
                 }
-            }catch (JsonSyntaxException e)
+            } catch (JsonSyntaxException e)
             {
                 System.out.println(e.getMessage());
                 logger.warn("onMessage had an exception parsing some json", e);
@@ -87,6 +88,15 @@ public static void onMessage(CertStreamMessageHandler handler)
         });
     }
 
+    private static Gson certStreamGson =
+            new GsonBuilder()
+                    .registerTypeAdapter
+                    (
+                        CertStreamCertificatePOJO.class,
+                        new CertStreamCertificatePOJODeserializer()
+                    )
+                    .create();
+
     /**
      * @param handler A {@link Consumer<CertStreamMessage>} that we'll
      *                run in a Thread that stays alive as long
@@ -99,7 +109,7 @@ public static void onMessageAlternativeServer (CertStreamMessageHandler handler,
             CertStreamMessagePOJO msg;
 
             try {
-                msg = new Gson().fromJson(string, CertStreamMessagePOJO.class);
+                msg = certStreamGson.fromJson(string, CertStreamMessagePOJO.class);
 
                 if (msg.messageType.equalsIgnoreCase("heartbeat")) {
                     return;

src/io/calidog/certstream/CertStreamCertificate.java

@@ -1,11 +1,8 @@
 package io.calidog.certstream;
 
-import sun.reflect.generics.reflectiveObjects.NotImplementedException;
-
 import javax.security.auth.x500.X500Principal;
 import java.math.BigInteger;
 import java.security.*;
-import java.security.cert.Certificate;
 import java.security.cert.*;
 import java.time.Instant;
 import java.util.*;
@@ -16,7 +13,7 @@
  */
 public class CertStreamCertificate extends X509Certificate {
     private HashMap<String, String> subject;
-    private HashMap<String, String> extensions;
+    private HashMap<String, String[]> extensions;
 
     private double notBefore;
     private double notAfter;
@@ -77,25 +74,25 @@ public void checkValidity(Date date) throws CertificateExpiredException, Certifi
     /**Not implemented*/
     @Override
     public int getVersion() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public BigInteger getSerialNumber() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public Principal getIssuerDN() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public X500Principal getIssuerX500Principal() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
@@ -122,66 +119,66 @@ public Date getNotAfter() {
     /**Not implemented*/
     @Override
     public byte[] getTBSCertificate() throws CertificateEncodingException {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
     /**Not implemented*/
     @Override
     public byte[] getSignature() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public String getSigAlgName() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public String getSigAlgOID() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public byte[] getSigAlgParams() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public boolean[] getIssuerUniqueID() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public boolean[] getSubjectUniqueID() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public boolean[] getKeyUsage() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public List<String> getExtendedKeyUsage() throws CertificateParsingException {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public int getBasicConstraints() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public Collection<List<?>> getSubjectAlternativeNames() throws CertificateParsingException {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     @Override
@@ -206,49 +203,49 @@ public byte[] getEncoded() throws CertificateEncodingException {
     /**Not implemented*/
     @Override
     public void verify(PublicKey publicKey) throws CertificateException, NoSuchAlgorithmException, InvalidKeyException, NoSuchProviderException, SignatureException {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public void verify(PublicKey publicKey, String s) throws CertificateException, NoSuchAlgorithmException, InvalidKeyException, NoSuchProviderException, SignatureException {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public String toString() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public PublicKey getPublicKey() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public boolean hasUnsupportedCriticalExtension() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public Set<String> getCriticalExtensionOIDs() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public Set<String> getNonCriticalExtensionOIDs() {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**Not implemented*/
     @Override
     public byte[] getExtensionValue(String s) {
-        throw new NotImplementedException();
+        throw new UnsupportedOperationException();
     }
 
     /**
@@ -257,7 +254,7 @@ public byte[] getExtensionValue(String s) {
      * passed-in oid String. The oid string is represented
      * by whatever CertStream passes us.
      */
-    public String getStringExtensionValue(String key)
+    public String[] getStringExtensionValue(String key)
     {
         return extensions.get(key);
     }

src/io/calidog/certstream/CertStreamCertificatePOJO.java

@@ -12,7 +12,9 @@ public class CertStreamCertificatePOJO {
 
     HashMap<String, String> subject;
 
-    HashMap<String, String> extensions;
+    // values can be either strings or lists of strings, so we use a a custom deserializer
+    // that converts strings into singleton arrays
+    HashMap<String, String[]> extensions;
 
     @SerializedName("not_before")
     double notBefore;

src/io/calidog/certstream/CertStreamCertificatePOJODeserializer.java

@@ -0,0 +1,60 @@
+package io.calidog.certstream;
+
+import com.google.gson.*;
+
+import java.lang.reflect.Type;
+import java.util.HashMap;
+import java.util.Map;
+
+public class CertStreamCertificatePOJODeserializer implements JsonDeserializer<CertStreamCertificatePOJO> {
+
+    @Override
+    public CertStreamCertificatePOJO deserialize(
+            JsonElement jsonElement,
+            Type type,
+            JsonDeserializationContext jsonDeserializationContext
+    ) throws JsonParseException {
+
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+        JsonObject jsonExtensions = new JsonObject();
+
+        // remove extensions from json object
+        if (jsonObj.has("extensions"))
+        {
+            jsonExtensions = jsonObj.remove("extensions").getAsJsonObject();
+        }
+
+        // parse entry normally
+        CertStreamCertificatePOJO retVal = new Gson().fromJson(jsonElement, CertStreamCertificatePOJO.class);
+
+        // parse extensions externally
+        retVal.extensions = deserializeExtension(jsonExtensions);
+
+        return retVal;
+    }
+
+    private HashMap<String, String[]> deserializeExtension(JsonObject extensions){
+        final HashMap<String, String[]> finalMap = new HashMap<>(extensions.size());
+
+        extensions.entrySet().forEach((Map.Entry<String, JsonElement> entry) -> {
+            String key = entry.getKey();
+            JsonElement value = entry.getValue();
+            String[] extensionValues;
+
+            try {
+                extensionValues = new String[] { value.getAsString() };
+            } catch (IllegalStateException | UnsupportedOperationException e) {
+                JsonArray extensionJsonArray = value.getAsJsonArray();
+                extensionValues = new String[extensionJsonArray.size()];
+
+                for (int i = 0; i < extensionJsonArray.size(); i++) {
+                    extensionValues[i] = extensionJsonArray.get(i).getAsString();
+                }
+            }
+
+            finalMap.put(key, extensionValues);
+        });
+
+        return finalMap;
+    }
+}