blob: 59da7d21b33b357ec2107eab80d2915716c47e8a [file] [log] [blame]
// 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/server.h"
#include <algorithm>
#include "pw_log/log.h"
#include "pw_rpc/internal/packet.h"
#include "pw_rpc/internal/server.h"
#include "pw_rpc/server_context.h"
namespace pw::rpc {
namespace {
using std::byte;
using internal::Packet;
using internal::PacketType;
bool DecodePacket(ChannelOutput& interface,
std::span<const byte> data,
Packet& packet) {
Result<Packet> result = Packet::FromBuffer(data);
if (!result.ok()) {
PW_LOG_WARN("Failed to decode packet on interface %s", interface.name());
return false;
}
packet = result.value();
// If the packet is malformed, don't try to process it.
if (packet.channel_id() == Channel::kUnassignedChannelId ||
packet.service_id() == 0 || packet.method_id() == 0) {
PW_LOG_WARN("Received incomplete packet on interface %s", interface.name());
// Only send an ERROR response if a valid channel ID was provided.
if (packet.channel_id() != Channel::kUnassignedChannelId) {
internal::Channel temp_channel(packet.channel_id(), &interface);
temp_channel.Send(Packet::ServerError(packet, Status::DataLoss()));
}
return false;
}
return true;
}
} // namespace
Server::~Server() {
// Since the writers remove themselves from the server in Finish(), remove the
// first writer until no writers remain.
while (!writers_.empty()) {
writers_.front().Finish();
}
}
Status Server::ProcessPacket(std::span<const byte> data,
ChannelOutput& interface) {
Packet packet;
if (!DecodePacket(interface, data, packet)) {
return Status::DataLoss();
}
if (packet.destination() != Packet::kServer) {
return Status::InvalidArgument();
}
internal::Channel* channel = FindChannel(packet.channel_id());
if (channel == nullptr) {
// If the requested channel doesn't exist, try to dynamically assign one.
channel = AssignChannel(packet.channel_id(), interface);
if (channel == nullptr) {
// If a channel can't be assigned, send a RESOURCE_EXHAUSTED error.
internal::Channel temp_channel(packet.channel_id(), &interface);
temp_channel.Send(
Packet::ServerError(packet, Status::ResourceExhausted()));
return OkStatus(); // OK since the packet was handled
}
}
const auto [service, method] = FindMethod(packet);
if (method == nullptr) {
channel->Send(Packet::ServerError(packet, Status::NotFound()));
return OkStatus();
}
switch (packet.type()) {
case PacketType::REQUEST: {
internal::ServerCall call(
static_cast<internal::Server&>(*this), *channel, *service, *method);
method->Invoke(call, packet);
break;
}
case PacketType::CLIENT_STREAM_END:
// TODO(hepler): Support client streaming RPCs.
break;
case PacketType::CLIENT_ERROR:
HandleClientError(packet);
break;
case PacketType::CANCEL_SERVER_STREAM:
HandleCancelPacket(packet, *channel);
break;
default:
channel->Send(Packet::ServerError(packet, Status::Unimplemented()));
PW_LOG_WARN("Unable to handle packet of type %u",
unsigned(packet.type()));
}
return OkStatus();
}
std::tuple<Service*, const internal::Method*> Server::FindMethod(
const internal::Packet& packet) {
// Packets always include service and method IDs.
auto service = std::find_if(services_.begin(), services_.end(), [&](auto& s) {
return s.id() == packet.service_id();
});
if (service == services_.end()) {
return {};
}
return {&(*service), service->FindMethod(packet.method_id())};
}
void Server::HandleCancelPacket(const Packet& packet,
internal::Channel& channel) {
auto writer = std::find_if(writers_.begin(), writers_.end(), [&](auto& w) {
return w.channel_id() == packet.channel_id() &&
w.service_id() == packet.service_id() &&
w.method_id() == packet.method_id();
});
if (writer == writers_.end()) {
channel.Send(Packet::ServerError(packet, Status::FailedPrecondition()));
PW_LOG_WARN("Received CANCEL packet for method that is not pending");
} else {
writer->Finish(Status::Cancelled());
}
}
void Server::HandleClientError(const Packet& packet) {
// A client error indicates that the client received a packet that it did not
// expect. If the packet belongs to a streaming RPC, cancel the stream without
// sending a final SERVER_STREAM_END packet.
auto writer = std::find_if(writers_.begin(), writers_.end(), [&](auto& w) {
return w.channel_id() == packet.channel_id() &&
w.service_id() == packet.service_id() &&
w.method_id() == packet.method_id();
});
if (writer != writers_.end()) {
writer->Close();
}
}
internal::Channel* Server::FindChannel(uint32_t id) const {
for (internal::Channel& c : channels_) {
if (c.id() == id) {
return &c;
}
}
return nullptr;
}
internal::Channel* Server::AssignChannel(uint32_t id,
ChannelOutput& interface) {
internal::Channel* channel = FindChannel(Channel::kUnassignedChannelId);
if (channel == nullptr) {
return nullptr;
}
*channel = internal::Channel(id, &interface);
return channel;
}
} // namespace pw::rpc