SocketHelper.cpp

#include <mutex>
#include <thread>

#include "SocketHelper.h"
#include "Constants.h"

#include "PlistCpp/Plist.hpp"
#include "PlistCpp/PlistDate.hpp"

int send_message(const char* message, SOCKET socket, long long length)
{
	LengthEncodedMessage length_encoded_message = get_message_with_encoded_length(message, length);
	return send(socket, length_encoded_message.message, length_encoded_message.length, 0);
}

int send_message(std::string message, SOCKET socket, long long length)
{
	return send_message(message.c_str(), socket, length);
}

int get_socket_state(SOCKET socket, int timeout)
{
	if (timeout < 0)
	{
		return 1;
	}

	// The code is stolen from here http://stackoverflow.com/questions/30395258/setting-timeout-to-recv-function
	fd_set set;
	struct timeval time_to_wait;
	FD_ZERO(&set); /* clear the set */
	FD_SET(socket, &set); /* add our file descriptor to the set */
	time_to_wait.tv_sec = timeout;
	// If we don't set tv_usec this method won't work.
	time_to_wait.tv_usec = 0;
	// We need the + 1 here because we add our socket to the set and the first param of the select (nfds)
	// is the maximum socket number to read from.
	// nfds is the highest-numbered file descriptor in any of the three sets, plus 1 - http://manpages.courier-mta.org/htmlman2/select.2.html
	int rv = select(socket + 1, &set, NULL, NULL, &time_to_wait);
	return rv;
}

std::mutex receive_message_mutex;
std::map<std::string, boost::any> receive_message_core(SOCKET socket)
{
	receive_message_mutex.lock();
	std::map<std::string, boost::any> dict;
	char *buffer = new char[4];
	int bytes_read = recv(socket, buffer, 4, 0);
	if (bytes_read > 0)
	{
		unsigned long res = ntohl(*((unsigned long*)buffer));
		delete[] buffer;
		buffer = new char[res];
		bytes_read = recv(socket, buffer, res, 0);
		if (bytes_read > 0)
		{
			Plist::readPlist(buffer, res, dict);
		}
	}

	delete[] buffer;
	receive_message_mutex.unlock();
	return dict;
}

std::map<std::string, boost::any> receive_message(SOCKET socket, int timeout)
{

	if (get_socket_state(socket, timeout) <= kSocketNoMessages)
	{
		return std::map<std::string, boost::any>();
	}

	return receive_message_core(socket);
}

Utf16Message* create_utf16_message(const std::string& message)
{
	Utf16Message* result = new Utf16Message();
	result->message = message;

	return result;
}

Utf16Message* receive_utf16_message(SOCKET fd, int size = 1024 * 1024)
{
	int bytes_read;

	// We need to create new unsigned char[] here because if we don't
	// the memcpy will fail with EXC_BAD_ACCESS
	std::string result;
	unsigned char *buffer = new unsigned char[size];

	do
	{
		// We do not want to stay at recv forever.
		// Also we need to check if there are messages before each recv because
		// the message can have length 2000 and we will try to call recv 3 times.
		// We will stay forever at the 3d one because there will be no message in the socket.
		int socket_state = get_socket_state(fd, 1);

		// If the MSG_PEEK flag is set the recv function won't read the data from the socket.
		// It will just return the size of the message in the socket.
		// If the size is 0 this means that the socket is closed.
		// This call is BLOCKING.
		bytes_read = recv(fd, (char*)buffer, size, MSG_PEEK);

		if (socket_state <= kSocketClosed || bytes_read <= 0)
		{
			delete[] buffer;
			// Socket is closed.
			if (result.length() > 0)
			{
				// Return the last received message before the socket was closed.
				return create_utf16_message(result);
			}
			else
			{
				return nullptr;
			}
		}

		bytes_read = recv(fd, (char*)buffer, size, 0);

		if (bytes_read > 0)
		{
			result.append(buffer, buffer + bytes_read);
		}
		else if (bytes_read < 0)
		{
			delete[] buffer;
			return nullptr;
		}
	} while (bytes_read == size);

	delete[] buffer;
	return create_utf16_message(result);
}

void proxy_socket_messages(SOCKET first, SOCKET second)
{
	Utf16Message* message;

	while ((message = receive_utf16_message(first)) != nullptr)
	{
		if (message->message.length())
		{
#ifdef _WIN32
			char* message_buffer = (char*)message->message.c_str();
#else
			const char* message_buffer = message->message.c_str();
#endif // _WIN32
			send(second, message_buffer, message->message.length(), NULL);
		}

		// Delete the message to free the message->message memory.
		delete message;
	}
}

void proxy_socket_io(SOCKET first, SOCKET second, SocketClosedCallback first_socket_closed_callback, SocketClosedCallback second_socket_closed_callback)
{
	std::thread([=]() {
		// Send the messages received on the first socket to the second socket.
		proxy_socket_messages(first, second);
		first_socket_closed_callback(second);
	}).detach();

	std::thread([=]() {
		// Send the messages received on the second socket to the first socket.
		proxy_socket_messages(second, first);
		second_socket_closed_callback(second);
	}).detach();
}

std::string receive_message_raw(SOCKET socket, int size)
{
	int bytes_read;
	std::string result = "";
	if (get_socket_state(socket, 1) == kSocketHasMessages)
	{
		do
		{
			char *buffer = new char[size];
			bytes_read = recv(socket, buffer, size, 0);
			if (bytes_read > 0)
				result += std::string(buffer, bytes_read);
			delete[] buffer;
		} while (bytes_read == size);
	}

	return result;
}

LengthEncodedMessage get_message_with_encoded_length(const char* message, long long length)
{
	if (length < 0)
		length = strlen(message);

	unsigned long message_len = length + 4;
	char *length_encoded_message = new char[message_len];
	unsigned long packed_length = htonl(length);
	size_t packed_length_size = 4;
	memcpy(length_encoded_message, &packed_length, packed_length_size);
	memcpy(length_encoded_message + packed_length_size, message, length);
	return{ length_encoded_message, message_len };
}

void close_socket(SOCKET socket) {
	// We need closesocket for Windows because the socket
	// is a handle to kernel object instead of *nix file descriptor
	// http://stackoverflow.com/questions/35441815/are-close-and-closesocket-interchangable
#ifdef _WIN32
	closesocket(socket);
#else
	close(socket);
#endif // _WIN32
}