Random bytes server for Windows.

randomd.cpp

// cl randomd.cpp /nologo /O2 /MD ws2_32.lib bcrypt.lib

// http://www.geekpage.jp/programming/winsock/
// http://code.msdn.microsoft.com/windowsdesktop/Random-Number-Generation-e5b88ccc/sourcecode?fileId=42843&pathId=1800936463

#include <windows.h>
//#include <tchar.h>
//#include <winsock2.h>
#include <bcrypt.h>
#include <stdio.h>
#include <winternl.h>

int main(int argc, char *argv[]) {
	if(argc < 2) {
		printf("usage: %s <port>\n", argv[0]);
		return 1;
	}

	int port = atoi(argv[1]);

	WSADATA wsa;
	int err;

	if((err = WSAStartup(MAKEWORD(2, 0), &wsa)) != 0) {
		printf("WSAStartup error: %08X\n", err);
		return 1;
	}

	SOCKET sock;
	if((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) { // AF? PF??
		printf("socket error: %08X\n", WSAGetLastError());
		return 1;
	}

	struct sockaddr_in addr;
	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
	addr.sin_addr.S_un.S_addr = INADDR_ANY;

	BOOL yes = 1;
	if((err = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char*)&yes, sizeof(yes))) != 0) {
		printf("setsockopt/SO_REUSEADDR error: %08X\n", err);
		return 1;
	}

	if((err = bind(sock, (struct sockaddr*)&addr, sizeof(addr))) != 0) {
		printf("bind error: %08X\n", err);
		return 1;
	}

	if((err = listen(sock, 5)) != 0) { // 5 backlog
		printf("listen error: %08X\n", err);
		return 1;
	}

	for(;;) {
		SOCKET s;
		struct sockaddr_in claddr;
		int len = sizeof(claddr);
		if((s = accept(sock, (struct sockaddr*)&claddr, &len)) == INVALID_SOCKET) {
			printf("accept error: %08X\n", WSAGetLastError());
			return 1;
		}

		printf("connection from %s:%d\n", inet_ntoa(claddr.sin_addr), ntohs(claddr.sin_port));

		for(;;) {
			unsigned char buf[4096];
			NTSTATUS st;

			if(!NT_SUCCESS(st = BCryptGenRandom(NULL, buf, sizeof(buf), BCRYPT_USE_SYSTEM_PREFERRED_RNG))) {
				printf("BCryptGenRandom error: %08X\n", st);
				break;
			}
			err = send(s, (const char*)buf, sizeof(buf), 0);
			if(err == SOCKET_ERROR) {
				err = WSAGetLastError();
				if(err == WSAECONNRESET) {
					printf("got WSAECONNRESET.\n", err);
				} else {
					printf("send error: %08X\n", err);
				}
				break;
			}
			if(err == 0) {
				printf("send returns 0...\n");
				break;
			}
			if(err < sizeof(buf)) {
				printf("send returns %d...\n", err);
				break;
			}
		}

		closesocket(s);
		printf("disconnected.\n");
	}

	WSACleanup();

	return 0;
}