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// Copyright 2020 The Pigweed Authors
// Licensed 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
// 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.
#include "pw_rpc/internal/method.h"
#include "pb_decode.h"
#include "pb_encode.h"
namespace pw::rpc::internal {
namespace {
// Nanopb 3 uses pb_field_s and Nanopb 4 uses pb_msgdesc_s for fields. The
// Nanopb version macro is difficult to use, so deduce the correct type from the
// pb_decode function.
template <typename DecodeFunction>
struct NanopbTraits;
template <typename FieldsType>
struct NanopbTraits<bool(pb_istream_t*, FieldsType, void*)> {
using Fields = FieldsType;
using Fields = typename NanopbTraits<decltype(pb_decode)>::Fields;
} // namespace
using std::byte;
Status Method::DecodeRequest(std::span<const byte> buffer,
void* proto_struct) const {
auto input = pb_istream_from_buffer(
reinterpret_cast<const pb_byte_t*>(, buffer.size());
return pb_decode(&input, static_cast<Fields>(request_fields_), proto_struct)
? Status::OK
: Status::INTERNAL;
StatusWithSize Method::EncodeResponse(const void* proto_struct,
std::span<byte> buffer) const {
auto output = pb_ostream_from_buffer(
reinterpret_cast<pb_byte_t*>(, buffer.size());
if (pb_encode(&output, static_cast<Fields>(response_fields_), proto_struct)) {
return StatusWithSize(output.bytes_written);
return StatusWithSize::INTERNAL;
StatusWithSize Method::CallUnary(ServerCall& call,
std::span<const byte> request_buffer,
std::span<byte> response_buffer,
void* request_struct,
void* response_struct) const {
Status status = DecodeRequest(request_buffer, request_struct);
if (!status.ok()) {
return StatusWithSize(status, 0);
status = function_.unary(call.context(), request_struct, response_struct);
StatusWithSize encoded = EncodeResponse(response_struct, response_buffer);
if (encoded.ok()) {
return StatusWithSize(status, encoded.size());
return encoded;
StatusWithSize Method::CallServerStreaming(ServerCall& call,
std::span<const byte> request_buffer,
void* request_struct) const {
Status status = DecodeRequest(request_buffer, request_struct);
if (!status.ok()) {
return StatusWithSize(status, 0);
internal::BaseServerWriter server_writer(call);
return StatusWithSize(
function_.server_streaming(call.context(), request_struct, server_writer),
} // namespace pw::rpc::internal