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LibIPC: Share most of the code between {Client,Server}Connection

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This patch introduces IPC::Connection which becomes the new base class
of ClientConnection and ServerConnection. Most of the functionality
has been hoisted up to the base class since almost all of it is useful
on both sides.

This gives us the ability to send synchronous messages in both
directions, which is needed for the WebContent server process.
Unlike other servers, WebContent does not mind blocking on a response
from its client.
This commit is contained in:
Andreas Kling 2020-09-12 11:44:00 +02:00
parent 633e0bc944
commit aba793fb3e
19 changed files with 293 additions and 260 deletions
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148
Libraries/LibIPC/ServerConnection.h
View file

@ -32,6 +32,7 @@
#include <LibCore/LocalSocket.h>
#include <LibCore/Notifier.h>
#include <LibCore/SyscallUtils.h>
#include <LibIPC/Connection.h>
#include <LibIPC/Message.h>
#include <stdio.h>
#include <stdlib.h>
@ -42,159 +43,44 @@
namespace IPC {
template<typename LocalEndpoint, typename PeerEndpoint>
class ServerConnection : public Core::Object {
template<typename ClientEndpoint, typename ServerEndpoint>
class ServerConnection : public IPC::Connection<ClientEndpoint, ServerEndpoint> {
public:
ServerConnection(LocalEndpoint& local_endpoint, const StringView& address)
: m_local_endpoint(local_endpoint)
, m_connection(Core::LocalSocket::construct(this))
, m_notifier(Core::Notifier::construct(m_connection->fd(), Core::Notifier::Read, this))
ServerConnection(ClientEndpoint& local_endpoint, const StringView& address)
: Connection<ClientEndpoint, ServerEndpoint>(local_endpoint, Core::LocalSocket::construct())
{
// We want to rate-limit our clients
m_connection->set_blocking(true);
m_notifier->on_ready_to_read = [this] {
drain_messages_from_server();
handle_messages();
this->socket().set_blocking(true);
this->notifier().on_ready_to_read = [this] {
this->drain_messages_from_peer();
this->handle_messages();
};
if (!m_connection->connect(Core::SocketAddress::local(address))) {
if (!this->socket().connect(Core::SocketAddress::local(address))) {
perror("connect");
ASSERT_NOT_REACHED();
}
ucred creds;
socklen_t creds_size = sizeof(creds);
if (getsockopt(m_connection->fd(), SOL_SOCKET, SO_PEERCRED, &creds, &creds_size) < 0) {
ASSERT_NOT_REACHED();
}
m_server_pid = creds.pid;
ASSERT(this->socket().is_connected());
ASSERT(m_connection->is_connected());
this->initialize_peer_info();
}
virtual void handshake() = 0;
pid_t server_pid() const { return m_server_pid; }
void set_server_pid(pid_t pid) { m_server_pid = pid; }
pid_t server_pid() const { return this->peer_pid(); }
void set_server_pid(pid_t pid) { this->set_peer_pid(pid); }
void set_my_client_id(int id) { m_my_client_id = id; }
int my_client_id() const { return m_my_client_id; }
template<typename MessageType>
OwnPtr<MessageType> wait_for_specific_message()
virtual void die() override
{
return wait_for_specific_endpoint_message<MessageType, LocalEndpoint>();
}
bool post_message(const Message& message)
{
auto buffer = message.encode();
int nwritten = write(m_connection->fd(), buffer.data(), buffer.size());
if (nwritten < 0) {
perror("write");
ASSERT_NOT_REACHED();
return false;
}
ASSERT(static_cast<size_t>(nwritten) == buffer.size());
return true;
}
template<typename RequestType, typename... Args>
OwnPtr<typename RequestType::ResponseType> send_sync(Args&&... args)
{
bool success = post_message(RequestType(forward<Args>(args)...));
ASSERT(success);
auto response = wait_for_specific_endpoint_message<typename RequestType::ResponseType, PeerEndpoint>();
ASSERT(response);
return response;
// Override this function if you don't want your app to exit if it loses the connection.
exit(0);
}
private:
template<typename MessageType, typename Endpoint>
OwnPtr<MessageType> wait_for_specific_endpoint_message()
{
for (;;) {
// Double check we don't already have the event waiting for us.
// Otherwise we might end up blocked for a while for no reason.
for (size_t i = 0; i < m_unprocessed_messages.size(); ++i) {
auto& message = m_unprocessed_messages[i];
if (message.endpoint_magic() != Endpoint::static_magic())
continue;
if (message.message_id() == MessageType::static_message_id())
return m_unprocessed_messages.take(i).template release_nonnull<MessageType>();
}
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(m_connection->fd(), &rfds);
int rc = Core::safe_syscall(select, m_connection->fd() + 1, &rfds, nullptr, nullptr, nullptr);
if (rc < 0) {
perror("select");
}
ASSERT(rc > 0);
ASSERT(FD_ISSET(m_connection->fd(), &rfds));
if (!drain_messages_from_server())
return nullptr;
}
}
bool drain_messages_from_server()
{
Vector<u8> bytes;
for (;;) {
u8 buffer[4096];
ssize_t nread = recv(m_connection->fd(), buffer, sizeof(buffer), MSG_DONTWAIT);
if (nread < 0) {
if (errno == EAGAIN)
break;
perror("recv");
exit(1);
return false;
}
if (nread == 0) {
dbg() << "EOF on IPC fd";
// FIXME: Dying is definitely not always appropriate!
exit(1);
return false;
}
bytes.append(buffer, nread);
}
size_t decoded_bytes = 0;
for (size_t index = 0; index < bytes.size(); index += decoded_bytes) {
auto remaining_bytes = ByteBuffer::wrap(bytes.data() + index, bytes.size() - index);
if (auto message = LocalEndpoint::decode_message(remaining_bytes, decoded_bytes)) {
m_unprocessed_messages.append(message.release_nonnull());
} else if (auto message = PeerEndpoint::decode_message(remaining_bytes, decoded_bytes)) {
m_unprocessed_messages.append(message.release_nonnull());
} else {
ASSERT_NOT_REACHED();
}
ASSERT(decoded_bytes);
}
if (!m_unprocessed_messages.is_empty()) {
deferred_invoke([this](auto&) {
handle_messages();
});
}
return true;
}
void handle_messages()
{
auto messages = move(m_unprocessed_messages);
for (auto& message : messages) {
if (message.endpoint_magic() == LocalEndpoint::static_magic())
m_local_endpoint.handle(message);
}
}
LocalEndpoint& m_local_endpoint;
RefPtr<Core::LocalSocket> m_connection;
RefPtr<Core::Notifier> m_notifier;
NonnullOwnPtrVector<Message> m_unprocessed_messages;
int m_server_pid { -1 };
int m_my_client_id { -1 };
};