fix(plugins) gRPC gateway uri para bool handling (#9180)

gRPC gateway should handle the "false" argument as false for boolean parameters.

This change is to be consistent with [grpc-gateway](https://github.com/grpc-ecosystem/grpc-gateway), where by `http://localhost:8090/v1/example/echo?stringv=false&boolean=false&number=1` you get:
```json
{
	"stringv": "false",
	"boolean": false,
	"number": 1
}
```
as echo.

Before this fix, any value passed to a boolean parameter is treated as a string and thus encoded as `true`.

Fix FTI-3335

kong/plugins/grpc-gateway/deco.lua

@@ -169,21 +169,42 @@ function deco.new(method, path, protofile)
   }, deco)
 end
 
+local function get_field_type(typ, field)
+  local _, _, field_typ = pb.field(typ, field)
+  return field_typ
+end
+
+local function encode_fix(v, typ)
+  if typ == "bool" then
+    -- special case for URI parameters
+    return v and v ~= "0" and v ~= "false"
+  end
+
+  return v
+end
+
 --[[
   // Set value `v` at `path` in table `t`
   // Path contains value address in dot-syntax. For example:
   // `path="a.b.c"` would lead to `t[a][b][c] = v`.
 ]]
-local function add_to_table( t, path, v )
+local function add_to_table( t, path, v, typ )
   local tab = t -- set up pointer to table root
+  local msg_typ = typ;
   for m in re_gmatch( path , "([^.]+)(\\.)?") do
     local key, dot = m[1], m[2]
+    msg_typ = get_field_type(msg_typ, key)
+
+    -- not argument that we concern with
+    if not msg_typ then
+      return
+    end
 
     if dot then
       tab[key] = tab[key] or {} -- create empty nested table if key does not exist
       tab = tab[key]
     else
-      tab[key] = v
+      tab[key] = encode_fix(v, msg_typ)
     end
   end
 
@@ -241,12 +262,11 @@ function deco:upstream(body)
           // For example: `GET /v1/messages/123456?revision=2&sub.subfield=foo`
           // translates into `payload = { sub = { subfield = "foo" }}`
         ]]--
-        add_to_table( payload, k, v )
+        add_to_table( payload, k, v, self.endpoint.input_type)
       end
     end
   end
   body = grpc_frame(0x0, pb.encode(self.endpoint.input_type, payload))
-
   return body
 end
 

spec/03-plugins/28-grpc-gateway/01-proxy_spec.lua

@@ -66,7 +66,7 @@ for _, strategy in helpers.each_strategy() do
       local body = res:read_body()
       local data = cjson.decode(body)
 
-      assert.same({reply = "hello john_doe"}, data)
+      assert.same({reply = "hello john_doe", boolean_test = false}, data)
     end)
 
     test("additional binding", function()
@@ -77,19 +77,66 @@ for _, strategy in helpers.each_strategy() do
 
       local data = cjson.decode((res:read_body()))
 
-      assert.same({reply = "hello john_doe"}, data)
+      assert.same({reply = "hello john_doe", boolean_test = false}, data)
     end)
 
     test("removes unbound query args", function()
-      local res, err = proxy_client:get("/v1/messages/john_doe?arg1=1&arg2=2")
+      local res, err = proxy_client:get("/v1/messages/john_doe?arg1=1&arg2.test=2")
 
       assert.equal(200, res.status)
       assert.is_nil(err)
 
       local body = res:read_body()
       local data = cjson.decode(body)
 
-      assert.same({reply = "hello john_doe"}, data)
+      assert.same({reply = "hello john_doe", boolean_test = false}, data)
+    end)
+
+    describe("boolean behavior", function ()
+      test("true", function()
+        local res, err = proxy_client:get("/v1/messages/legacy/john_doe?boolean_test=true")
+        assert.equal(200, res.status)
+        assert.is_nil(err)
+
+        local body = res:read_body()
+        local data = cjson.decode(body)
+        assert.same({reply = "hello john_doe", boolean_test = true}, data)
+      end)
+
+      test("false", function()
+        local res, err = proxy_client:get("/v1/messages/legacy/john_doe?boolean_test=false")
+
+        assert.equal(200, res.status)
+        assert.is_nil(err)
+
+        local body = res:read_body()
+        local data = cjson.decode(body)
+
+        assert.same({reply = "hello john_doe", boolean_test = false}, data)
+      end)
+
+      test("zero", function()
+        local res, err = proxy_client:get("/v1/messages/legacy/john_doe?boolean_test=0")
+
+        assert.equal(200, res.status)
+        assert.is_nil(err)
+
+        local body = res:read_body()
+        local data = cjson.decode(body)
+
+        assert.same({reply = "hello john_doe", boolean_test = false}, data)
+      end)
+
+      test("non-zero", function()
+        local res, err = proxy_client:get("/v1/messages/legacy/john_doe?boolean_test=1")
+        assert.equal(200, res.status)
+        assert.is_nil(err)
+
+        local body = res:read_body()
+        local data = cjson.decode(body)
+
+        assert.same({reply = "hello john_doe", boolean_test = true}, data)
+      end)
     end)
 
     test("unknown path", function()

spec/fixtures/grpc/target/grpc-target.go

@@ -7,9 +7,10 @@ import (
 	"net"
 	"time"
 
+	pb "target/targetservice"
+
 	"google.golang.org/grpc"
 	"google.golang.org/protobuf/types/known/timestamppb"
-	pb "target/targetservice"
 )
 
 const (
@@ -22,7 +23,8 @@ type server struct {
 
 func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloResponse, error) {
 	return &pb.HelloResponse{
-		Reply: fmt.Sprintf("hello %s", in.GetGreeting()),
+		Reply:       fmt.Sprintf("hello %s", in.GetGreeting()),
+		BooleanTest: in.GetBooleanTest(),
 	}, nil
 }
 

spec/fixtures/grpc/targetservice.proto

@@ -49,10 +49,12 @@ service Bouncer {
 
 message HelloRequest {
   string greeting = 1;
+  bool boolean_test = 2;
 }
 
 message HelloResponse {
   string reply = 1;
+  bool boolean_test = 2;
 }