Sample Programs using the Win32 API for CS344-001 Term Essay

echo_server.c

/**
 * Author: Jonah George
 * Date: December 11, 2014
 * Description: A simple echo server using the Winsock2 Api
 * References: http://msdn.microsoft.com/en-us/library/windows/desktop/ms737593(v=vs.85).aspx
 */

#undef UNICODE

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>

#pragma comment (lib, "Ws2_32.lib")

#define BUFFER_LENGTH 512
#define PORT 4040

int main(int argc, char * argv[])
{
	WSADATA data;
	SOCKET ServerSocket = INVALID_SOCKET;
	SOCKET ClientSocket = INVALID_SOCKET;
	struct addrinfo * result = NULL;
	struct addrinfo * ptr = NULL;
	struct addrinfo hints;
	char recv_str[BUFFER_LENGTH];
	int ret;
	
	// Initialize Winsock
	ret = WSAStartup(MAKEWORD(2, 2), &data);
	if (ret != 0)
	{
		printf("WSAStartup failed with error: %d\n", ret);
		return 1;
	}

	// Win32 equivalent of memset(..., 0, ...);
	ZeroMemory(&hints, sizeof(hints));
	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	hints.ai_flags = AI_PASSIVE; // Open a passive socket for listening

	// Resolve the server address and port
	// Binding to 0.0.0.0:8080 since NULL in server_name didn't work
	ret = getaddrinfo("0.0.0.0", "8080", &hints, &result);
	if (ret != 0)
	{
		printf("getaddrinfo failed with error: %d\n", GetLastError());
		WSACleanup();
		return 1;
	}

	// Create a socket for listening on the server
	ServerSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
	if (ServerSocket == INVALID_SOCKET) 
	{
		printf("socket failed with error: %ld\n", WSAGetLastError());
		freeaddrinfo(result);
		WSACleanup();
		return 1;
	}

	// Bind the listening socket
	ret = bind(ServerSocket, result->ai_addr, (int) result->ai_addrlen);
	if (ret == SOCKET_ERROR) 
	{
		printf("bind failed with error: %d\n", WSAGetLastError());
		freeaddrinfo(result);
		closesocket(ServerSocket);
		WSACleanup();
		return 1;
	}

	// Free the addrinfo struct because we have active sockets
	freeaddrinfo(result);

	// Put server socket in listen mode
	ret = listen(ServerSocket, SOMAXCONN);
	if (ret == SOCKET_ERROR) 
	{
		printf("listen failed with error: %d\n", WSAGetLastError());
		closesocket(ServerSocket);
		WSACleanup();
		return 1;
	}

	// Accept a client socket
	ClientSocket = accept(ServerSocket, NULL, NULL);
	if (ClientSocket == INVALID_SOCKET) 
	{
		printf("accept failed with error: %d\n", WSAGetLastError());
		closesocket(ClientSocket);
		WSACleanup();
		return 1;
	}

	// No longer need server socket
	closesocket(ServerSocket);

	ret = 0;
	while (ret > 0) 
	{
		ret = recv(ClientSocket, recv_str, BUFFER_LENGTH, 0);

		// Valid message from client
		if (ret > 0) 
		{
			// Print client's messages
			printf("Client sent: %s\n", recv_str);

			// Echo the message back to the client
			ret = send(ClientSocket, recv_str, ret, 0);
			if (ret == SOCKET_ERROR) 
			{
				printf("send failed with error: %d\n", WSAGetLastError());
				closesocket(ClientSocket);
				WSACleanup();
				return 1;
			}
		}

		// Client closed connection
		else if (ret == 0) 
		{
			printf("Connection closing...\n");
		}

		// Error handling if recv() failed
		else  
		{
			printf("recv failed with error: %d\n", WSAGetLastError());
			closesocket(ClientSocket);
			WSACleanup();
			return 1;
		}

	}

	// Shutdown the client socket
	ret = shutdown(ClientSocket, SD_SEND);
	if (ret == SOCKET_ERROR) 
	{
		printf("shutdown failed with error: %d\n", WSAGetLastError());
		closesocket(ClientSocket);
		WSACleanup();
		return 1;
	}

	// Cleanup resources
	closesocket(ClientSocket);
	WSACleanup();

	// Exit successfully
	return 0;
}

file_io.c

/**
 * Author: Jonah George
 * Date: December 10, 2014
 * Description: This file demonstrates basic usage of the Win32 file i/o commands.
 */

#include <tchar.h>
#include <stdio.h>
#include <windows.h>

#define BUFFERSIZE 1024

int main(int argc, char *argv[])
{
	HANDLE file;
	BOOL ret;
	LPTSTR filename = _T("C:\\Users\\jonahgeorge\\Desktop\\test.txt");
	char write_str[] = "Hello, world\n";
	char recv_str[BUFFERSIZE];

	// Open file for writing
	// the CREATE_ALWAYS flag means that we will overwrite any pre-existing file
	file = CreateFile(
		filename,
		GENERIC_READ | GENERIC_WRITE,
		0,
		NULL,
		CREATE_ALWAYS,
		FILE_ATTRIBUTE_NORMAL,
		NULL
		);

	// Error handling if CreateFile() fails
	if (file == INVALID_HANDLE_VALUE)
	{
		printf("Could not create file\n");
		return 1;
	}

	// Write write_str to the file
	ret = WriteFile(
		file,
		write_str,
		strlen(write_str),
		NULL,
		NULL
		);

	// Error handling if WriteFile() fails
	if (ret == FALSE)
	{
		printf("Could not write file\n");
		return 1;
	}

	// Read file into recv_str
	ret = ReadFile(
		file,
		recv_str,
		BUFFERSIZE - 1,
		NULL,
		NULL
		);

	// Error handling if ReadFile() fails
	if (ret == FALSE)
	{
		DWORD error = GetLastError();

		if (error == ERROR_IO_PENDING)
			printf("Read operating is pending asynchronous operation\n");

		else
			printf("Could not read file\n");

		return 1;
	}
	else
	{
		printf("Contents: %s\n", recv_str);
	}

	// Close the file handle
	CloseHandle(file);

	// Exit successfully
	return 0;
}

multithreading.c

/**
 * Author: Jonah George
 * Date: December 11, 2014
 * Description: This file demonstrates basic usage of the Win32 thread functions.
 *              By creating 50 threads, simulating work on each thread and then waiting
 *              for the threads to return.
 */

// Required for rand_s()
#define _CRT_RAND_S

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <windows.h>

#define MAX_THREADS 50

// Function for each thread to run
// Simulates "work"
void * run_thread(void * ptr)
{
	int work_duration;
	unsigned int number;

	// Get the id for the current thread to use as an identifier
	DWORD id = GetCurrentThreadId();

	printf("#%d: Generating work\n", id);

	// Thread-safe randon number generator
	rand_s(&number);
	work_duration = number % 1000;

	printf("#%d: Working for %d milliseconds\n", id, work_duration);

	// Sleep for x milliseconds
	Sleep(work_duration);

	printf("#%d: Finished work\n", id);
	return NULL;
}

int main(int argc, char * argv[])
{
	HANDLE threads[MAX_THREADS];
	int i;

	// Create threads
	for (i = 0; i < MAX_THREADS; i++)
	{
		threads[i] = CreateThread(
			NULL,   // Thread handle CANNOT be inherited by child processes
			0,      // Use default stack size
			(void *) run_thread, // Pointer to the function to be run by thread
			NULL,   // Parameters for function
			0,      // Thread runs immediately after creation
			NULL    // Do not return thread identifier
			);

		// Error handling if CreateThread() fails
		if (threads[i] == NULL)
		{
			printf("CreateThread() failed\n");
			return 1;
		}
	}

	// Wait for each thread
	for (i = 0; i < MAX_THREADS; i++)
	{
		WaitForSingleObject(threads[i], INFINITE);
	}

	// Exit successfully
	return 0;
}

http://stackoverflow.com/questions/331536/windows-threading-beginthread-vs-beginthreadex-vs-createthread-c

http://msdn.microsoft.com/en-us/library/esszf9hw.aspx