Node: fix leak of sent metadata

src/node/ext/call.cc

@@ -99,7 +99,6 @@ Local<Value> nanErrorWithCode(const char *msg, grpc_call_error code) {
 
 bool CreateMetadataArray(Local<Object> metadata, grpc_metadata_array *array) {
   HandleScope scope;
-  grpc_metadata_array_init(array);
   Local<Array> keys = Nan::GetOwnPropertyNames(metadata).ToLocalChecked();
   for (unsigned int i = 0; i < keys->Length(); i++) {
     Local<String> current_key = Nan::To<String>(
@@ -111,18 +110,20 @@ bool CreateMetadataArray(Local<Object> metadata, grpc_metadata_array *array) {
     array->capacity += Local<Array>::Cast(value_array)->Length();
   }
   array->metadata = reinterpret_cast<grpc_metadata*>(
-      gpr_malloc(array->capacity * sizeof(grpc_metadata)));
+      gpr_zalloc(array->capacity * sizeof(grpc_metadata)));
   for (unsigned int i = 0; i < keys->Length(); i++) {
     Local<String> current_key(Nan::To<String>(keys->Get(i)).ToLocalChecked());
     Local<Array> values = Local<Array>::Cast(
         Nan::Get(metadata, current_key).ToLocalChecked());
-    grpc_slice key_slice = grpc_slice_intern(CreateSliceFromString(current_key));
+    grpc_slice key_slice = CreateSliceFromString(current_key);
+    grpc_slice key_intern_slice = grpc_slice_intern(key_slice);
+    grpc_slice_unref(key_slice);
     for (unsigned int j = 0; j < values->Length(); j++) {
       Local<Value> value = Nan::Get(values, j).ToLocalChecked();
       grpc_metadata *current = &array->metadata[array->count];
-      current->key = key_slice;
+      current->key = key_intern_slice;
       // Only allow binary headers for "-bin" keys
-      if (grpc_is_binary_header(key_slice)) {
+      if (grpc_is_binary_header(key_intern_slice)) {
         if (::node::Buffer::HasInstance(value)) {
           current->value = CreateSliceFromBuffer(value);
         } else {
@@ -142,6 +143,14 @@ bool CreateMetadataArray(Local<Object> metadata, grpc_metadata_array *array) {
   return true;
 }
 
+void DestroyMetadataArray(grpc_metadata_array *array) {
+  for (size_t i = 0; i < array->count; i++) {
+    // Don't unref keys because they are interned
+    grpc_slice_unref(array->metadata[i].value);
+  }
+  grpc_metadata_array_destroy(array);
+}
+
 Local<Value> ParseMetadata(const grpc_metadata_array *metadata_array) {
   EscapableHandleScope scope;
   grpc_metadata *metadata_elements = metadata_array->metadata;
@@ -179,6 +188,12 @@ Op::~Op() {
 
 class SendMetadataOp : public Op {
  public:
+  SendMetadataOp() {
+    grpc_metadata_array_init(&send_metadata);
+  }
+  ~SendMetadataOp() {
+    DestroyMetadataArray(&send_metadata);
+  }
   Local<Value> GetNodeValue() const {
     EscapableHandleScope scope;
     return scope.Escape(Nan::True());
@@ -187,17 +202,16 @@ class SendMetadataOp : public Op {
     if (!value->IsObject()) {
       return false;
     }
-    grpc_metadata_array array;
     MaybeLocal<Object> maybe_metadata = Nan::To<Object>(value);
     if (maybe_metadata.IsEmpty()) {
       return false;
     }
     if (!CreateMetadataArray(maybe_metadata.ToLocalChecked(),
-                             &array)) {
+                             &send_metadata)) {
       return false;
     }
-    out->data.send_initial_metadata.count = array.count;
-    out->data.send_initial_metadata.metadata = array.metadata;
+    out->data.send_initial_metadata.count = send_metadata.count;
+    out->data.send_initial_metadata.metadata = send_metadata.metadata;
     return true;
   }
   bool IsFinalOp() {
@@ -207,6 +221,8 @@ class SendMetadataOp : public Op {
   std::string GetTypeString() const {
     return "send_metadata";
   }
+ private:
+  grpc_metadata_array send_metadata;
 };
 
 class SendMessageOp : public Op {
@@ -272,8 +288,12 @@ class SendClientCloseOp : public Op {
 
 class SendServerStatusOp : public Op {
  public:
+  SendServerStatusOp() {
+    grpc_metadata_array_init(&status_metadata);
+  }
   ~SendServerStatusOp() {
     grpc_slice_unref(details);
+    DestroyMetadataArray(&status_metadata);
   }
   Local<Value> GetNodeValue() const {
     EscapableHandleScope scope;
@@ -313,12 +333,13 @@ class SendServerStatusOp : public Op {
     }
     Local<String> details = Nan::To<String>(
         maybe_details.ToLocalChecked()).ToLocalChecked();
-    grpc_metadata_array array;
-    if (!CreateMetadataArray(metadata, &array)) {
+    if (!CreateMetadataArray(metadata, &status_metadata)) {
       return false;
     }
-    out->data.send_status_from_server.trailing_metadata_count = array.count;
-    out->data.send_status_from_server.trailing_metadata = array.metadata;
+    out->data.send_status_from_server.trailing_metadata_count =
+        status_metadata.count;
+    out->data.send_status_from_server.trailing_metadata =
+        status_metadata.metadata;
     out->data.send_status_from_server.status =
         static_cast<grpc_status_code>(code);
     this->details = CreateSliceFromString(details);
@@ -335,6 +356,7 @@ class SendServerStatusOp : public Op {
 
  private:
   grpc_slice details;
+  grpc_metadata_array status_metadata;
 };
 
 class GetMetadataOp : public Op {

src/node/ext/call.h

@@ -58,6 +58,8 @@ v8::Local<v8::Value> ParseMetadata(const grpc_metadata_array *metadata_array);
 bool CreateMetadataArray(v8::Local<v8::Object> metadata,
                          grpc_metadata_array *array);
 
+void DestroyMetadataArray(grpc_metadata_array *array);
+
 /* Wrapper class for grpc_call structs. */
 class Call : public Nan::ObjectWrap {
  public:

src/node/ext/call_credentials.cc

@@ -211,6 +211,7 @@ NAN_METHOD(PluginCallback) {
   Utf8String details_utf8_str(info[1]);
   char *details = *details_utf8_str;
   grpc_metadata_array array;
+  grpc_metadata_array_init(&array);
   Local<Object> callback_data = Nan::To<Object>(info[3]).ToLocalChecked();
   if (!CreateMetadataArray(Nan::To<Object>(info[2]).ToLocalChecked(),
                            &array)){
@@ -226,6 +227,7 @@ NAN_METHOD(PluginCallback) {
                Nan::New("user_data").ToLocalChecked()
                ).ToLocalChecked().As<External>()->Value();
   cb(user_data, array.metadata, array.count, code, details);
+  DestroyMetadataArray(&array);
 }
 
 NAUV_WORK_CB(SendPluginCallback) {