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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 {
Result<Packet> Packet::FromBuffer(ConstByteSpan data) {
Packet packet;
Status status;
protobuf::Decoder decoder(data);
while ((status = decoder.Next()).ok()) {
RpcPacket::Fields field =
static_cast<RpcPacket::Fields>(decoder.FieldNumber());
switch (field) {
case RpcPacket::Fields::TYPE: {
uint32_t value;
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadUint32(&value).IgnoreError();
packet.set_type(static_cast<PacketType>(value));
break;
}
case RpcPacket::Fields::CHANNEL_ID:
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadUint32(&packet.channel_id_).IgnoreError();
break;
case RpcPacket::Fields::SERVICE_ID:
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadFixed32(&packet.service_id_).IgnoreError();
break;
case RpcPacket::Fields::METHOD_ID:
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadFixed32(&packet.method_id_).IgnoreError();
break;
case RpcPacket::Fields::PAYLOAD:
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadBytes(&packet.payload_).IgnoreError();
break;
case RpcPacket::Fields::STATUS: {
uint32_t value;
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadUint32(&value).IgnoreError();
packet.set_status(static_cast<Status::Code>(value));
break;
}
case RpcPacket::Fields::CALL_ID:
// A decode error will propagate from Next() and terminate the loop.
decoder.ReadUint32(&packet.call_id_).IgnoreError();
break;
}
}
if (status.IsDataLoss()) {
return status;
}
// TODO(b/234879973): CANCEL is equivalent to CLIENT_ERROR with status
// CANCELLED. Remove this workaround when CANCEL is removed.
if (packet.type() == PacketType::DEPRECATED_CANCEL) {
packet.set_status(Status::Cancelled());
}
return packet;
}
Result<ConstByteSpan> Packet::Encode(ByteSpan buffer) const {
RpcPacket::MemoryEncoder rpc_packet(buffer);
// The payload is encoded first, as it may share the encode buffer.
if (!payload_.empty()) {
rpc_packet.WritePayload(payload_).IgnoreError();
}
rpc_packet.WriteType(type_).IgnoreError();
rpc_packet.WriteChannelId(channel_id_).IgnoreError();
rpc_packet.WriteServiceId(service_id_).IgnoreError();
rpc_packet.WriteMethodId(method_id_).IgnoreError();
// Status code 0 is OK. In protobufs, 0 is the default int value, so skip
// encoding it to save two bytes in the output.
if (status_.code() != 0) {
rpc_packet.WriteStatus(status_.code()).IgnoreError();
}
if (call_id_ != 0) {
rpc_packet.WriteCallId(call_id_).IgnoreError();
}
if (rpc_packet.status().ok()) {
return ConstByteSpan(rpc_packet);
}
return rpc_packet.status();
}
size_t Packet::MinEncodedSizeBytes() const {
size_t reserved_size = 0;
reserved_size += 1; // channel_id key
reserved_size += varint::EncodedSize(channel_id());
reserved_size += 1 + sizeof(uint32_t); // service_id key and fixed32
reserved_size += 1 + sizeof(uint32_t); // method_id key and fixed32
// Packet type always takes two bytes to encode (varint key + varint enum).
reserved_size += 2;
// Status field takes up to 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;
}
} // namespace pw::rpc::internal