为什么套接字在多线程时不工作

我有一个非常简单的recvfrom()命令，只要不在"另一个"线程中调用，它就可以正常工作。

我会发布更多的代码，但其中有很多，所以希望我能过滤掉相关的部分：首先我们有一个全局变量：SOCKET Socket=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);。

只要不涉及线程，这就可以很好地工作：

char message[_max_message_];
struct sockaddr_in* from;
int r;
    int SenderAddrSize = sizeof (struct sockaddr);
    r=recvfrom(Socket,message,_max_message_,0,(struct sockaddr *)&from,&SenderAddrSize);
    printf("Bytes recieved: %inError Code: %in",r,WSAGetLastError);

现在，我在线程后面调用了相同的代码，如下所示：pthread_create(&listener, NULL, listenloop, &Socket);

（代码基本忽略&socket。）

来自被调用线程的第一个执行的recvfrom()返回-1，但来自"原始"线程（其中设置了网络）的recvfrom()成功地用来自服务器的消息填充了message。

好心地告诉我我做错了什么？

编辑：我不喜欢对好心帮助我的陌生人说十几句话，但如果我不这样做，我想我不会得到答案。所以，这是经过轻微编辑的工具包和kaboodle：

#include <iostream>
//#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <conio.h>
using namespace std;
#include <string>
//One thread shall listen continually for responses from the server.
/*The other thread shall listen continually for user input, and fire off user input at the local
 client to the server...*/
//#ifdef _WINDOWS
#include <winsock2.h>
#include <ws2tcpip.h>
#include <windows.h>
SOCKET Socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
inline int randport()
{
  return (50000 % rand() + 1000);
}
#define _serverip_ "***.***.***.***"
#define _welcome_ "Welcome,Wagon!"
#define _randomport_ 64000%rand()+100
#define _max_message_ 100
void *listenloop(void *arg)
{
  //SOCKET* listener = (SOCKET)arg;
  WSADATA WsaDat;
  WSAStartup(MAKEWORD(2, 0), &WsaDat);
  char message[_max_message_];
  //SOCKET listener=(SOCKET)arg;
  int r;
  //sockaddr_in SenderAddr;
  struct sockaddr_in from;
  //while (1){
  int SenderAddrSize = sizeof(struct sockaddr);
  r = recvfrom(Socket, message, _max_message_, 0, (struct sockaddr *) &from,
      &SenderAddrSize);
  printf("Thread Bytes recieved: %inThread Error Code: %in", r,
      WSAGetLastError);
  return NULL ;
  //}
  return NULL ;
}
int main()
{
  string user, pass, login;
  WSADATA WsaDat;
  WSAStartup(MAKEWORD(2, 0), &WsaDat);
  int port;
  cout << "Welcome!"
  SOCKET Socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
  fflush(stdin); //As long as we compile with GCC Behavoir should be consistant
  //TRY NOT TO SEND PLAINTEXT PASSWORDS LIKE THIS!  IT MAY MAKE YOUR USERS VULNERABLE!  DONE FOR SAKE OF SIMPLICITY HERE!
  cout << "nnPlease enter the username you registered with:";
  getline(cin, user);
  cout << "nPlease enter your password, my good sir: ";
  getline(cin, pass);
  struct hostent *host;
  host = gethostbyaddr(_serverip_, strlen(_serverip_), AF_INET);
  if (host == NULL )
  {
    cout << "nn UNABLE TO CONNECT TO SERVER.  QUITTING. ";
    return -1;
  }
  short errorcount = 3;
  int socketfeedback;
  ///Put the address for the server on the "evelope"
  SOCKADDR_IN SockAddr;
  SockAddr.sin_port = htons(port);
  SockAddr.sin_family = AF_INET;
  SockAddr.sin_addr.s_addr = inet_addr(_serverip_);
  ///Sign the letter...
  int myport = _randomport_;
  int code;
  SOCKADDR_IN service;
  service.sin_family = AF_INET;
  service.sin_addr.s_addr = inet_addr("localhost");
  service.sin_port = htons(myport);
  //bind(Socket, (SOCKADDR *) &service, sizeof(service));
  //Start a thread, listening for that server
  while ((errorcount))
  {
    code = bind(Socket, (SOCKADDR *) &service, sizeof(service));
    if (code)
      break;
    else
      return -5;
    errorcount--;
    myport = _randomport_;
    service.sin_port = htons(myport);
  }
  login = user + ',' + pass;
  if (!errorcount)
  {
    cout << "nnMiserable failure.  Last Known Error Code: " << code;
    return -1;
  }
  ///Begin the listen loop!!
  pthread_t listener;
  pthread_create(&listener, NULL, listenloop, &Socket);
  struct sockaddr result;
  sendto(Socket, login.c_str(), strlen(login.c_str()), 0,
      (struct sockaddr *) &SockAddr, sizeof(SockAddr));
  char message[_max_message_];
  //SOCKET listener=(SOCKET)arg;
  //sockaddr_in SenderAddr;
  struct sockaddr_in from;
  int r;
  int SenderAddrSize = sizeof(struct sockaddr);
  r = recvfrom(Socket, message, _max_message_, 0, (struct sockaddr *) &from,
      &SenderAddrSize);
  printf("Bytes recieved: %inError Code: %in", r, WSAGetLastError);
  //SOCKET listener=(SOCKET)arg;
  WSACleanup();
  return 0;
}