interfaces.cpp

// Copyright (c) 2021-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <common/args.h>
#include <common/system.h>
#include <interfaces/init.h>
#include <interfaces/ipc.h>
#include <ipc/capnp/protocol.h>
#include <ipc/process.h>
#include <ipc/protocol.h>
#include <tinyformat.h>
#include <util/fs.h>
#include <util/log.h>

#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <memory>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

#ifndef WIN32
#include <unistd.h>
#endif

namespace ipc {
namespace {
#ifndef WIN32
std::string g_ignore_ctrl_c;

void HandleCtrlC(int)
{
    // (void)! needed to suppress -Wunused-result warning from GCC
    (void)!write(STDOUT_FILENO, g_ignore_ctrl_c.data(), g_ignore_ctrl_c.size());
}
#endif

void IgnoreCtrlC(std::string message)
{
#ifndef WIN32
    g_ignore_ctrl_c = std::move(message);
    struct sigaction sa{};
    sa.sa_handler = HandleCtrlC;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    sigaction(SIGINT, &sa, nullptr);
#endif
}

class IpcImpl : public interfaces::Ipc
{
public:
    IpcImpl(const char* exe_name, const char* process_argv0, interfaces::Init& init)
        : m_exe_name(exe_name), m_process_argv0(process_argv0), m_init(init),
          m_protocol(ipc::capnp::MakeCapnpProtocol(exe_name)), m_process(ipc::MakeProcess())
    {
    }
    std::unique_ptr<interfaces::Init> spawnProcess(const char* new_exe_name) override
    {
        const auto [pid, socket] = m_process->spawn(new_exe_name, m_process_argv0);
        LogDebug(::BCLog::IPC, "Process %s pid %i launched\n", new_exe_name, pid);
        auto init = m_protocol->connect(m_protocol->makeStream(socket));
        Ipc::addCleanup(*init, [this, new_exe_name, pid] {
            int status = m_process->waitSpawned(pid);
            LogDebug(::BCLog::IPC, "Process %s pid %i exited with status %i\n", new_exe_name, pid, status);
        });
        return init;
    }
    bool startSpawnedProcess(int argc, char* argv[], int& exit_status) override
    {
        exit_status = EXIT_FAILURE;
        mp::SocketId socket{mp::SocketError};
        if (!m_process->checkSpawned(argc, argv, socket)) {
            return false;
        }
        IgnoreCtrlC(strprintf("[%s] SIGINT received — waiting for parent to shut down.\n", m_exe_name));
        m_protocol->serve(m_init, [&] { return m_protocol->makeStream(socket); } );
        exit_status = EXIT_SUCCESS;
        return true;
    }
    std::unique_ptr<interfaces::Init> connectAddress(std::string& address) override
    {
        if (address.empty() || address == "0") return nullptr;
        mp::SocketId fd;
        if (address == "auto") {
            // Treat "auto" the same as "unix" except don't treat it an as error
            // if the connection is not accepted. Just return null so the caller
            // can work offline without a connection, or spawn a new
            // bitcoin-node process and connect to it.
            address = "unix";
            try {
                fd = m_process->connect(gArgs.GetDataDirNet(), "bitcoin-node", address);
            } catch (const std::system_error& e) {
                // If connection type is auto and socket path isn't accepting connections, or doesn't exist, catch the error and return null;
                if (e.code() == std::errc::connection_refused || e.code() == std::errc::no_such_file_or_directory || e.code() == std::errc::not_a_directory) {
                    return nullptr;
                }
                throw;
            } catch (const std::invalid_argument&) {
               // Catch 'Unix address path "..." exceeded maximum socket path length' error
               return nullptr;
            }
        } else {
            fd = m_process->connect(gArgs.GetDataDirNet(), "bitcoin-node", address);
        }
        return m_protocol->connect(m_protocol->makeStream(fd));
    }
    void listenAddress(std::string& address) override
    {
        mp::SocketId fd = m_process->bind(gArgs.GetDataDirNet(), m_exe_name, address);
        m_protocol->listen(fd, m_init);
    }
    void disconnectIncoming() override
    {
        m_protocol->disconnectIncoming();
    }
    void addCleanup(std::type_index type, void* iface, std::function<void()> cleanup) override
    {
        m_protocol->addCleanup(type, iface, std::move(cleanup));
    }
    Context& context() override { return m_protocol->context(); }
    const char* m_exe_name;
    const char* m_process_argv0;
    interfaces::Init& m_init;
    std::unique_ptr<Protocol> m_protocol;
    std::unique_ptr<Process> m_process;
};
} // namespace
} // namespace ipc

namespace interfaces {
std::unique_ptr<Ipc> MakeIpc(const char* exe_name, const char* process_argv0, Init& init)
{
    return std::make_unique<ipc::IpcImpl>(exe_name, process_argv0, init);
}
} // namespace interfaces