#ifndef WIN32   #include <arpa/inet.h>#else   #include <winsock2.h>   #include <ws2tcpip.h>#endif#include <fstream>#include <iostream>#include <cstdlib>#include <cstring>#include <udt.h>using namespace std;int main(int argc, char* argv[]){   if ((argc != 5) || (0 == atoi(argv[2])))   {      cout << "usage: recvfile server_ip server_port remote_filename local_filename" << endl;      return 0;   }   // use this function to initialize the UDT library   UDT::startup();   UDTSOCKET fhandle = UDT::socket(AF_INET, SOCK_STREAM, 0);   sockaddr_in serv_addr;   serv_addr.sin_family = AF_INET;   serv_addr.sin_port = htons(short(atoi(argv[2])));#ifndef WIN32   if (inet_pton(AF_INET, argv[1], &serv_addr.sin_addr) <= 0)#else   if (INADDR_NONE == (serv_addr.sin_addr.s_addr = inet_addr(argv[1])))#endif   {      cout << "incorrect network address.\n";      return 0;   }   memset(&(serv_addr.sin_zero), '\0', 8);   if (UDT::ERROR == UDT::connect(fhandle, (sockaddr*)&serv_addr, sizeof(serv_addr)))   {      cout << "connect: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   // send name information of the requested file   int len = strlen(argv[3]);   if (UDT::ERROR == UDT::send(fhandle, (char*)&len, sizeof(int), 0))   {      cout << "send: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   if (UDT::ERROR == UDT::send(fhandle, argv[3], len, 0))   {      cout << "send: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   // get size information   int64_t size;   if (UDT::ERROR == UDT::recv(fhandle, (char*)&size, sizeof(int64_t), 0))   {      cout << "send: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   // receive the file   ofstream ofs(argv[4], ios::out | ios::binary | ios::trunc);   int64_t recvsize;    if (UDT::ERROR == (recvsize = UDT::recvfile(fhandle, ofs, 0, size)))   {      cout << "recvfile: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   UDT::close(fhandle);   ofs.close();   // use this function to release the UDT library   UDT::cleanup();   return 1;}