#ifndef WIN32   #include <cstdlib>#else   #include <winsock2.h>   #include <ws2tcpip.h>#endif#include <fstream>#include <iostream>#include <cstring>#include <udt.h>using namespace std;int main(int argc, char* argv[]){   //usage: sendfile [server_port]   if ((2 < argc) || ((2 == argc) && (0 == atoi(argv[1]))))   {      cout << "usage: sendfile [server_port]" << endl;      return 0;   }   // use this function to initialize the UDT library   UDT::startup();   UDTSOCKET serv = UDT::socket(AF_INET, SOCK_STREAM, 0);#ifdef WIN32   int mss = 1052;   UDT::setsockopt(serv, 0, UDT_MSS, &mss, sizeof(int));#endif   int port = 9000;   if (2 == argc)      port = atoi(argv[1]);   sockaddr_in my_addr;   my_addr.sin_family = AF_INET;   my_addr.sin_port = htons(port);   my_addr.sin_addr.s_addr = INADDR_ANY;   memset(&(my_addr.sin_zero), '\0', 8);   if (UDT::ERROR == UDT::bind(serv, (sockaddr*)&my_addr, sizeof(my_addr)))   {      cout << "bind: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   cout << "server is ready at port: " << port << endl;   UDT::listen(serv, 1);   sockaddr_in their_addr;   int namelen = sizeof(their_addr);   UDTSOCKET fhandle;   if (UDT::INVALID_SOCK == (fhandle = UDT::accept(serv, (sockaddr*)&their_addr, &namelen)))   {      cout << "accept: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   UDT::close(serv);   // aquiring file name information from client   char file[1024];   int len;   if (UDT::ERROR == UDT::recv(fhandle, (char*)&len, sizeof(int), 0))   {      cout << "recv: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   if (UDT::ERROR == UDT::recv(fhandle, file, len, 0))   {      cout << "recv: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   file[len] = '\0';   // open the file   ifstream ifs(file, ios::in | ios::binary);   ifs.seekg(0, ios::end);   int64_t size = ifs.tellg();   ifs.seekg(0, ios::beg);   // send file size information   if (UDT::ERROR == UDT::send(fhandle, (char*)&size, sizeof(int64_t), 0))   {      cout << "send: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   UDT::TRACEINFO trace;   UDT::perfmon(fhandle, &trace);   // send the file   if (UDT::ERROR == UDT::sendfile(fhandle, ifs, 0, size))   {      cout << "sendfile: " << UDT::getlasterror().getErrorMessage() << endl;      return 0;   }   UDT::perfmon(fhandle, &trace);   cout << "speed = " << trace.mbpsSendRate << "Mbits/sec" << endl;   UDT::close(fhandle);   ifs.close();   // use this function to release the UDT library   UDT::cleanup();   return 1;}