Сервер сокетов домена UNIX и клиент не взаимодействуют в двух направлениях

Я написал сервер C ++ и клиент PHP, оба общались на основе доменных сокетов UNIX. Чтение ИЛИ запись в любом направлении работает просто отлично. Как только я пытаюсь прочитать И затем написать (или наоборот), связь не завершается: клиент через некоторое время возвращает «504 Gateway Time-out», а сервер просто продолжает ждать после печати «Ожидание аутентификации …» ».

PHP-клиент:

<?php
$sock = socket_create(AF_UNIX, SOCK_STREAM, 0);
$conn = socket_connect($sock, '/tmp/some.socket');$pass = "pass\0";

if ($sock == FALSE)
echo "Error: <br />   $errstr ($errno)<br />\n";
else
{
echo "Sending the password... ";

$ret = socket_write($sock, $pass, strlen($pass));

if ($ret == FALSE)
echo "error! " .  socket_strerror( socket_last_error());
else
{
echo "Password was sent.<br /> ";

$auth = socket_read($sock, 256);

if (FALSE === $auth)
echo "sending password failed; reason: " . socket_strerror(socket_last_error($sock)) . "\n";
else if ($auth != "authenticated")
echo "Authentication failed: $auth.";
else
echo "Authentication was successful. <br />";
}
}

socket_close($sock);

?>

Файл cpp главного сервера:

#include <iostream>

#include "UnixDomainSocket.hpp"

int main()
{
try
{
UnixDomainSocket uds("/tmp/some.socket");

std::cout << "Server started." << std::endl;

while (true)
{
//if a new connection stablished, read and process data
if (uds.newConnectionEstablished())
{
std::cout << "Got a new connection. Waiting for authentication..." << std::endl;

std::string command = uds.getClientMsg().getValue();

if (command != "pass")
{
std::cout << "401" << std::endl;
uds.sendMsg("401");
}
else
{
std::cout << "authenticated" << std::endl;

auto msgRet = uds.sendMsg("authenticated");
}

uds.closeConnection();
}
}
}
catch (const std::string & err)
{
std::cout << "Error: " << err << std::endl;

return -1;
}
catch (const std::exception & err)
{
std::cout << "Error: " << std::string(err.what()) << std::endl;

return -1;
}
catch (...)
{
std::cout << "Unhandled error occured. Daemon stopped." << std::endl;

return -1;
}
std::cout << "Server shut down." << std::endl;
}

Заголовок сервера:

#ifndef UNIXDOMAINSOCKET_HPP
#define UNIXDOMAINSOCKET_HPP

#include <sys/un.h>
#include <sys/socket.h>
#include <unistd.h>

#include <string>

#include "Expected.hpp"

const int BUFFSIZE = 1024;

class UnixDomainSocket
{
public:
UnixDomainSocket (const std::string & socketPath);
~UnixDomainSocket();

bool newConnectionEstablished();
Expected<std::string> getClientMsg();
Expected<bool> sendMsg (const std::string & msg);
void closeConnection();
void closeConnection (const std::string & quitMessage);

protected:
std::string socketPath;
unsigned long maxConnections;
bool connectionEstablished;

struct sockaddr_un addr;
int serverFileDescriptor, clientFileDescriptor;
ssize_t bytes;
char buf[BUFFSIZE];
};

#endif

Сервер cpp:

#include "UnixDomainSocket.hpp"
#include <iostream>UnixDomainSocket::UnixDomainSocket (const std::string & socketPath)
: socketPath(socketPath), maxConnections(100)
{
if ((serverFileDescriptor = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
throw "socket  error";

memset (&addr, 0, sizeof(addr));

//ensure that all fields, including non−standard ones, are initialized to 0
addr.sun_family = AF_UNIX;

//we copy one byte less, ensuring a trailing 0 exists
strncpy(addr.sun_path, socketPath.c_str(), sizeof(addr.sun_path) - 1);if (access(addr.sun_path, F_OK) == 0)
unlink(addr.sun_path);

if (bind(serverFileDescriptor, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) < 0)
throw "bind error";

if (listen(serverFileDescriptor, maxConnections) < 0)
throw "listen error";
}

UnixDomainSocket::~UnixDomainSocket()
{
closeConnection();
}

bool UnixDomainSocket::newConnectionEstablished()
{
if ((clientFileDescriptor = accept(serverFileDescriptor, NULL, NULL)) < 0)
throw "accept error";

connectionEstablished = true;

return true;
}

Expected<std::string> UnixDomainSocket::getClientMsg()
{
if (!connectionEstablished)
return Expected<std::string>::fromException(std::logic_error("No connection established yet."));

std::string msg;

while ((bytes = read (clientFileDescriptor, buf, BUFFSIZE)) > 0)
msg += buf;

// if (msg.length())
//     throw "empty msg from client";

if (bytes < 0)
throw "read error";

return msg;
}

Expected<bool> UnixDomainSocket::sendMsg (const std::string & msg)
{
if (!connectionEstablished)
return Expected<bool>::fromException(std::logic_error("No connection established yet."));

if (msg.empty())
return Expected<bool>::fromException(std::logic_error("The message must be not empty."));auto bytesSent = send(clientFileDescriptor, (msg + "\n").c_str(), msg.length(), MSG_CONFIRM);

////Also tried:
// long bytesSent = -1;
// while (bytesSent < 0)
//     bytesSent = write(clientFileDescriptor, msg.c_str(), msg.length());

if (bytesSent != msg.length())
return Expected<bool>::fromException(std::logic_error("Error occured while sending."));

return true;
}void UnixDomainSocket::closeConnection (const std::string & quitMessage)
{
sendMsg(quitMessage);
closeConnection();
}

void UnixDomainSocket::closeConnection()
{
if (close(clientFileDescriptor) < 0)
throw "close error";

connectionEstablished = false;
}