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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
//
// https://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.
#include "pw_rpc/internal/packet.h"
#include "pw_protobuf/decoder.h"
namespace pw::rpc::internal {
using std::byte;
Packet Packet::FromBuffer(span<const byte> data) {
PacketType type = PacketType::RPC;
uint32_t channel_id = 0;
uint32_t service_id = 0;
uint32_t method_id = 0;
span<const byte> payload;
Status status;
uint32_t value;
protobuf::Decoder decoder(data);
while (decoder.Next().ok()) {
RpcPacket::Fields field =
static_cast<RpcPacket::Fields>(decoder.FieldNumber());
uint32_t proto_value = 0;
switch (field) {
case RpcPacket::Fields::TYPE:
decoder.ReadUint32(&proto_value);
type = static_cast<PacketType>(proto_value);
break;
case RpcPacket::Fields::CHANNEL_ID:
decoder.ReadUint32(&channel_id);
break;
case RpcPacket::Fields::SERVICE_ID:
decoder.ReadUint32(&service_id);
break;
case RpcPacket::Fields::METHOD_ID:
decoder.ReadUint32(&method_id);
break;
case RpcPacket::Fields::PAYLOAD:
decoder.ReadBytes(&payload);
break;
case RpcPacket::Fields::STATUS:
decoder.ReadUint32(&value);
status = static_cast<Status::Code>(value);
break;
}
}
return Packet(type, channel_id, service_id, method_id, payload, status);
}
StatusWithSize Packet::Encode(span<byte> buffer) const {
pw::protobuf::NestedEncoder encoder(buffer);
RpcPacket::Encoder rpc_packet(&encoder);
// The payload is encoded first, as it may share the encode buffer.
rpc_packet.WritePayload(payload_);
rpc_packet.WriteType(type_);
rpc_packet.WriteChannelId(channel_id_);
rpc_packet.WriteServiceId(service_id_);
rpc_packet.WriteMethodId(method_id_);
rpc_packet.WriteStatus(status_);
span<const byte> proto;
if (Status status = encoder.Encode(&proto); !status.ok()) {
return StatusWithSize(status, 0);
}
return StatusWithSize(proto.size());
}
span<byte> Packet::PayloadUsableSpace(span<byte> buffer) const {
size_t reserved_size = 0;
reserved_size += 1; // channel_id key
reserved_size += varint::EncodedSize(channel_id());
reserved_size += 1; // service_id key
reserved_size += varint::EncodedSize(service_id());
reserved_size += 1; // method_id key
reserved_size += varint::EncodedSize(method_id());
// Packet type always takes two bytes to encode (varint key + varint enum).
reserved_size += 2;
// Status field always takes two bytes to encode (varint key + varint status).
reserved_size += 2;
// Payload field takes at least two bytes to encode (varint key + length).
reserved_size += 2;
return reserved_size <= buffer.size() ? buffer.subspan(reserved_size)
: span<byte>();
}
} // namespace pw::rpc::internal