서버 튜터링

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#define WIN32_LEAN_AND_MEAN
#include <WinSock2.h>
#include <stdio.h>

#pragma comment(lib, "ws2_32")

#define LOCALPORT 2000
#define BUFSIZE 512

void errDisplay(const char* msg) {
   LPVOID IpMsgBuf;

   FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
      NULL, WSAGetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
      (LPTSTR)&IpMsgBuf, 0, NULL);
   printf("[%s] %s\n", msg, (char)IpMsgBuf);
   LocalFree(IpMsgBuf);
}

int main(int argc, char argv[]) {
   int iResult;
   WSADATA wasData;

   if (WSAStartup(MAKEWORD(2, 2), &wasData) != 0) {
      printf("WSAStartup(): 윈속 초기화 오류\n");
      return 1;
   }

   SOCKET dataSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
   if (dataSocket == INVALID_SOCKET) {
      errDisplay("socket()");
      WSACleanup();
      return 1;

   }

   SOCKADDR_IN localAddr;
   ZeroMemory(&localAddr, sizeof(localAddr));
   localAddr.sin_family = AF_INET;
   localAddr.sin_port = htons(LOCALPORT);
   localAddr.sin_addr.s_addr = htons(INADDR_ANY);
   iResult = bind(dataSocket, (SOCKADDR)&localAddr, sizeof(localAddr));
   if (iResult == SOCKET_ERROR) {
      errDisplay("bind");
      closesocket(dataSocket);
      WSACleanup();
      return 1;
   }

   SOCKADDR_IN peerAddr;
   int addrLength;
   char buffer[BUFSIZE + 1];

   addrLength = sizeof(peerAddr);
   while (1) {
      ZeroMemory(buffer, sizeof(buffer));
      iResult = recvfrom(dataSocket, buffer, BUFSIZE, 0, (SOCKADDR)&peerAddr, &addrLength);
      if (iResult == SOCKET_ERROR) {
         errDisplay("recvfrom()");
         break;
      }

      buffer[iResult] = '\n';
      printf("[UDP from %s port %d] %s", inet_ntoa(peerAddr.sin_addr), ntohs(peerAddr.sin_port), buffer);
   }
   closesocket(dataSocket);
   WSACleanup();
   return 0;
}

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