fix(grpc-transcode): serialize empty repeated fields as JSON arrays instead of objects

apisix/plugins/grpc-transcode/proto.lua

@@ -20,6 +20,7 @@ local pb            = require("pb")
 local protoc        = require("protoc")
 local pcall         = pcall
 local ipairs        = ipairs
+local pairs         = pairs
 local decode_base64 = ngx.decode_base64
 
 
@@ -29,6 +30,94 @@ local lrucache_proto = core.lrucache.new({
 })
 
 local proto_fake_file = "filename for loaded"
+local FIELD_TYPE_MESSAGE = 11
+
+local function ensure_package_prefix(package)
+    if package and package ~= "" then
+        return "." .. package .. "."
+    end
+
+    return "."
+end
+
+local function create_field_descriptor(field)
+    return {
+        name = field.name,
+        label = field.label,
+        type = field.type,
+        type_name = field.type_name,
+    }
+end
+
+local function register_message_descriptor(index, message, prefix)
+    local full_name = prefix .. message.name
+    local descriptor = {
+        full_name = full_name,
+        fields = {},
+        map_entry = message.options and message.options.map_entry or false,
+    }
+
+    for _, field in ipairs(message.field or {}) do
+        descriptor.fields[field.name] = create_field_descriptor(field)
+    end
+
+    index[full_name] = descriptor
+
+    local nested_prefix = full_name .. "."
+    for _, nested in ipairs(message.nested_type or {}) do
+        register_message_descriptor(index, nested, nested_prefix)
+    end
+end
+
+local function build_message_index_from_file(index, file)
+    if not file then
+        return
+    end
+
+    local prefix = ensure_package_prefix(file.package)
+    for _, message in ipairs(file.message_type or {}) do
+        register_message_descriptor(index, message, prefix)
+    end
+end
+
+local function mark_map_fields(index)
+    for _, descriptor in pairs(index) do
+        if descriptor.map_entry and descriptor.fields then
+            descriptor.map_value_field = descriptor.fields.value
+        end
+    end
+
+    for _, descriptor in pairs(index) do
+        for _, field in pairs(descriptor.fields) do
+            if field.type == FIELD_TYPE_MESSAGE and field.type_name then
+                local target = index[field.type_name]
+                if target and target.map_entry then
+                    field.is_map = true
+                    field.map_entry_descriptor = target
+                end
+            end
+        end
+    end
+end
+
+local function build_message_index(files)
+    local index = {}
+    if not files then
+        return index
+    end
+
+    if files.message_type or files.package then
+        build_message_index_from_file(index, files)
+    else
+        for _, file in ipairs(files) do
+            build_message_index_from_file(index, file)
+        end
+    end
+
+    mark_map_fields(index)
+
+    return index
+end
 
 local function compile_proto_text(content)
     protoc.reload()
@@ -60,6 +149,7 @@ local function compile_proto_text(content)
     end
 
     compiled[proto_fake_file].index = index
+    compiled.message_index = build_message_index(compiled[proto_fake_file])
 
     return compiled
 end
@@ -93,6 +183,7 @@ local function compile_proto_bin(content)
     local compiled = {}
     compiled[proto_fake_file] = {}
     compiled[proto_fake_file].index = index
+    compiled.message_index = build_message_index(files)
     return compiled
 end
 

apisix/plugins/grpc-transcode/response.lua

@@ -23,6 +23,58 @@ local string = string
 local ngx_decode_base64 = ngx.decode_base64
 local ipairs = ipairs
 local pcall  = pcall
+local type          = type
+local pairs         = pairs
+local setmetatable  = setmetatable
+
+local _M = {}
+
+-- Protobuf repeated field label value
+local PROTOBUF_REPEATED_LABEL = 3
+local FIELD_TYPE_MESSAGE = 11
+
+local function set_default_array(tab, descriptor, message_index)
+    if type(tab) ~= "table" or not descriptor or not descriptor.fields then
+        return
+    end
+
+    for field_name, field_info in pairs(descriptor.fields) do
+        local value = tab[field_name]
+        if value ~= nil and type(value) == "table" then
+            if field_info.label == PROTOBUF_REPEATED_LABEL and not field_info.is_map then
+                setmetatable(value, core.json.array_mt)
+            end
+
+            if field_info.type == FIELD_TYPE_MESSAGE then
+                if field_info.is_map then
+                    local map_entry = field_info.map_entry_descriptor
+                    local map_value_field = map_entry and map_entry.map_value_field
+                    if map_value_field and map_value_field.type == FIELD_TYPE_MESSAGE then
+                        local nested_desc = message_index and
+                                            message_index[map_value_field.type_name]
+                        if nested_desc then
+                            for _, map_val in pairs(value) do
+                                set_default_array(map_val, nested_desc, message_index)
+                            end
+                        end
+                    end
+                else
+                    local nested_desc = message_index and
+                                        message_index[field_info.type_name]
+                    if nested_desc then
+                        if field_info.label == PROTOBUF_REPEATED_LABEL then
+                            for _, item in ipairs(value) do
+                                set_default_array(item, nested_desc, message_index)
+                            end
+                        else
+                            set_default_array(value, nested_desc, message_index)
+                        end
+                    end
+                end
+            end
+        end
+    end
+end
 
 
 local function handle_error_response(status_detail_type, proto)
@@ -93,7 +145,8 @@ local function handle_error_response(status_detail_type, proto)
 end
 
 
-return function(ctx, proto, service, method, pb_option, show_status_in_body, status_detail_type)
+local function transform_response(ctx, proto, service, method, pb_option,
+    show_status_in_body, status_detail_type)
     local buffer = core.response.hold_body_chunk(ctx)
     if not buffer then
         return nil
@@ -132,6 +185,14 @@ return function(ctx, proto, service, method, pb_option, show_status_in_body, sta
         return err_msg
     end
 
+    local message_index = proto and proto.message_index
+    if message_index then
+        local output_descriptor = message_index[m.output_type]
+        if output_descriptor then
+            set_default_array(decoded, output_descriptor, message_index)
+        end
+    end
+
     local response, err = core.json.encode(decoded)
     if not response then
         err_msg = "failed to json_encode response body"
@@ -142,3 +203,13 @@ return function(ctx, proto, service, method, pb_option, show_status_in_body, sta
     ngx.arg[1] = response
     return nil
 end
+
+_M._TEST = {
+    set_default_array = set_default_array,
+}
+
+return setmetatable(_M, {
+    __call = function(_, ...)
+        return transform_response(...)
+    end
+})

t/plugin/grpc-transcode-arrays.t

@@ -0,0 +1,158 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+no_long_string();
+no_shuffle();
+no_root_location();
+
+add_block_preprocessor(sub {
+    my ($block) = @_;
+
+    if (!$block->request) {
+        $block->set_value("request", "GET /t");
+    }
+});
+
+run_tests;
+
+__DATA__
+
+=== TEST 1: repeated field name scoped to its message
+--- config
+    location /t {
+        content_by_lua_block {
+            local response = require("apisix.plugins.grpc-transcode.response")
+            local helpers = response._TEST
+
+            local message_index = {
+                [".demo.Company"] = {
+                    fields = {
+                        name = {label = 3, type = 9},
+                    },
+                },
+                [".demo.InnerName"] = {
+                    fields = {
+                        part = {label = 1, type = 9},
+                    },
+                },
+                [".demo.HelloRequest"] = {
+                    fields = {
+                        company = {label = 1, type = 11, type_name = ".demo.Company"},
+                        name = {label = 1, type = 11, type_name = ".demo.InnerName"},
+                    },
+                }
+            }
+
+            local data = {
+                company = { name = {"foo", "bar"} },
+                name = { part = "ceo" },
+            }
+
+            helpers.set_default_array(data,
+                message_index[".demo.HelloRequest"], message_index)
+
+            local array_mt = require("apisix.core").json.array_mt
+
+            if getmetatable(data.company.name) ~= array_mt then
+                ngx.status = 500
+                ngx.say("company.name isn't treated as an array")
+                return
+            end
+
+            if getmetatable(data.name) == array_mt then
+                ngx.status = 500
+                ngx.say("nested message incorrectly converted to array")
+                return
+            end
+
+            ngx.say("passed")
+        }
+    }
+--- response_body
+passed
+
+
+
+=== TEST 2: map values keep object semantics while nested arrays are applied
+--- config
+    location /t {
+        content_by_lua_block {
+            local response = require("apisix.plugins.grpc-transcode.response")
+            local helpers = response._TEST
+
+            local member_descriptor = {
+                fields = {
+                    alias = {label = 3, type = 9},
+                }
+            }
+
+            local map_entry_descriptor = {
+                map_entry = true,
+                fields = {
+                    key = {label = 1, type = 9},
+                    value = {label = 1, type = 11, type_name = ".demo.Member"},
+                },
+            }
+            map_entry_descriptor.map_value_field = map_entry_descriptor.fields.value
+
+            local team_descriptor = {
+                fields = {
+                    members = {
+                        label = 3,
+                        type = 11,
+                        type_name = ".demo.Team.MemberEntry",
+                        is_map = true,
+                        map_entry_descriptor = map_entry_descriptor,
+                    }
+                }
+            }
+
+            local message_index = {
+                [".demo.Member"] = member_descriptor,
+                [".demo.Team.MemberEntry"] = map_entry_descriptor,
+                [".demo.Team"] = team_descriptor,
+            }
+
+            local data = {
+                members = {
+                    alice = { alias = {"aa", "ab"} },
+                    bob = { alias = {"ba"} },
+                }
+            }
+
+            helpers.set_default_array(data, message_index[".demo.Team"], message_index)
+
+            local array_mt = require("apisix.core").json.array_mt
+
+            if getmetatable(data.members) == array_mt then
+                ngx.status = 500
+                ngx.say("map field should not become an array")
+                return
+            end
+
+            if getmetatable(data.members.alice.alias) ~= array_mt then
+                ngx.status = 500
+                ngx.say("map values should still apply nested arrays")
+                return
+            end
+
+            ngx.say("passed")
+        }
+    }
+--- response_body
+passed