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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/core/broker.h"
#include <fcntl.h>
#include <unistd.h>
#include <utility>
#include <vector>
#include "base/logging.h"
#include "base/memory/platform_shared_memory_region.h"
#include "build/build_config.h"
#include "mojo/buildflags.h"
#include "mojo/core/broker_messages.h"
#include "mojo/core/channel.h"
#include "mojo/core/platform_handle_utils.h"
#include "mojo/public/cpp/platform/socket_utils_posix.h"
namespace mojo {
namespace core {
namespace {
Channel::MessagePtr WaitForBrokerMessage(
int socket_fd,
BrokerMessageType expected_type,
size_t expected_num_handles,
size_t expected_data_size,
std::vector<PlatformHandle>* incoming_handles) {
Channel::MessagePtr message = Channel::Message::CreateMessage(
sizeof(BrokerMessageHeader) + expected_data_size, expected_num_handles);
std::vector<base::ScopedFD> incoming_fds;
ssize_t read_result =
SocketRecvmsg(socket_fd, const_cast<void*>(message->data()),
message->data_num_bytes(), &incoming_fds, true /* block */);
bool error = false;
if (read_result < 0) {
PLOG(ERROR) << "Recvmsg error";
error = true;
} else if (static_cast<size_t>(read_result) != message->data_num_bytes()) {
LOG(ERROR) << "Invalid node channel message";
error = true;
} else if (incoming_fds.size() != expected_num_handles) {
DLOG(ERROR) << "Received unexpected number of handles";
error = true;
}
if (error)
return nullptr;
const BrokerMessageHeader* header =
reinterpret_cast<const BrokerMessageHeader*>(message->payload());
if (header->type != expected_type) {
LOG(ERROR) << "Unexpected message";
return nullptr;
}
incoming_handles->reserve(incoming_fds.size());
for (size_t i = 0; i < incoming_fds.size(); ++i)
incoming_handles->emplace_back(std::move(incoming_fds[i]));
return message;
}
} // namespace
Broker::Broker(PlatformHandle handle, bool wait_for_channel_handle)
: sync_channel_(std::move(handle)) {
CHECK(sync_channel_.is_valid());
int fd = sync_channel_.GetFD().get();
// Mark the channel as blocking.
int flags = fcntl(fd, F_GETFL);
PCHECK(flags != -1);
flags = fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
PCHECK(flags != -1);
if (!wait_for_channel_handle)
return;
// Wait for the first message, which should contain a handle.
std::vector<PlatformHandle> incoming_platform_handles;
if (WaitForBrokerMessage(fd, BrokerMessageType::INIT, 1, 0,
&incoming_platform_handles)) {
inviter_endpoint_ =
PlatformChannelEndpoint(std::move(incoming_platform_handles[0]));
}
}
Broker::~Broker() = default;
PlatformChannelEndpoint Broker::GetInviterEndpoint() {
return std::move(inviter_endpoint_);
}
base::WritableSharedMemoryRegion Broker::GetWritableSharedMemoryRegion(
size_t num_bytes) {
base::AutoLock lock(lock_);
BufferRequestData* buffer_request;
Channel::MessagePtr out_message = CreateBrokerMessage(
BrokerMessageType::BUFFER_REQUEST, 0, 0, &buffer_request);
buffer_request->size = num_bytes;
ssize_t write_result =
SocketWrite(sync_channel_.GetFD().get(), out_message->data(),
out_message->data_num_bytes());
if (write_result < 0) {
PLOG(ERROR) << "Error sending sync broker message";
return base::WritableSharedMemoryRegion();
} else if (static_cast<size_t>(write_result) !=
out_message->data_num_bytes()) {
LOG(ERROR) << "Error sending complete broker message";
return base::WritableSharedMemoryRegion();
}
#if !BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_ANDROID) || \
BUILDFLAG(MOJO_USE_APPLE_CHANNEL)
// Non-POSIX systems, as well as Android and Mac, only use a single handle to
// represent a writable region.
constexpr size_t kNumExpectedHandles = 1;
#else
constexpr size_t kNumExpectedHandles = 2;
#endif
std::vector<PlatformHandle> handles;
Channel::MessagePtr message = WaitForBrokerMessage(
sync_channel_.GetFD().get(), BrokerMessageType::BUFFER_RESPONSE,
kNumExpectedHandles, sizeof(BufferResponseData), &handles);
if (message) {
const BufferResponseData* data;
if (!GetBrokerMessageData(message.get(), &data))
return base::WritableSharedMemoryRegion();
std::optional<base::UnguessableToken> guid =
base::UnguessableToken::Deserialize(data->guid_high, data->guid_low);
if (!guid.has_value()) {
return base::WritableSharedMemoryRegion();
}
if (handles.size() == 1)
handles.emplace_back();
return base::WritableSharedMemoryRegion::Deserialize(
base::subtle::PlatformSharedMemoryRegion::Take(
CreateSharedMemoryRegionHandleFromPlatformHandles(
std::move(handles[0]), std::move(handles[1])),
base::subtle::PlatformSharedMemoryRegion::Mode::kWritable,
num_bytes, guid.value()));
}
return base::WritableSharedMemoryRegion();
}
} // namespace core
} // namespace mojo
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