UDP to UDP 数据转发

目的
    希望读者在阅读本文之前，已经读过了《『黑客编程』一、TCP to TCP 数据转发》，UDP to UDP可以用作QQ通过转发代理聊天的功能。
应用机器A，提供UDP端口的服务，转发代理机器B，提供UDP转发端口服务，客户机C通过UDP把数据发送到B,B再转发给A，并把A发送的数据转发
给C。

设计
//主程序
Main()
{
   beginthread(u2uMainThread());
}

//主线程
u2uMainThread(Param)
{
   while(true)
   {
      创建"本地接收数据SOCK"，用来接收并转发客户端C发送过来的数据
      while(read>0)
      {
         等待并接收客户端C数据
  等到后，查找"目标SOCK"
  if(没有找到)
  {
      创建一个新的"目标SOCK"
     "目标SOCK"创建成功后，创建"Wait Thread"，
  }
  用"目标SOCK"发送数据到应用A
      }
   }
}
//Wait 线程 
Wait Thread(Param)
{
  创建"目标SOCK"->"连接SOCK"数据转发Thread
  等待这个线程结束
  释放SOCK资源
}
//TCP2TCP数据转发线程
UDP2UDP Thread(Param)
{
   SOCK FROM,TO
   while(read  >0)
   {
readfrom(From,Buff);
Sendto(To,Buff);
   }
}

参考代码
参数结构
struct AGENTTCPUDPGATEWAYINFO
{
char TargetIP[40];
int TargetPort;
int LocalPort;
int LocalTmpPort;
};

//主线程
DWORD WINAPI  u2umainthread(LPVOID lpvoid)
{
//获取参数
AGENTTCPUDPGATEWAYINFO *pasi = (AGENTTCPUDPGATEWAYINFO*)lpvoid;
AGENTTCPUDPGATEWAYINFO asi;
memcpy(&asi,pasi,sizeof(AGENTTCPUDPGATEWAYINFO));
delete pasi; pasi = NULL;
//-b

int iRet;
struct sockaddr_in UDPLocal,Target;
SOCKET s[2];//s[0]=>UDP socket s[1]=>TCP socket
HANDLE hThread[2]={NULL,NULL};

printf("\nOK!Work mode is udp2udp.");

//监听本地UDP port的地址结构
UDPLocal.sin_family=AF_INET;
UDPLocal.sin_addr.s_addr=INADDR_ANY;
UDPLocal.sin_port=htons(asi.LocalPort);
//目标地址结构
Target.sin_family=AF_INET;
Target.sin_addr.s_addr=inet_addr(asi.TargetIP);
Target.sin_port=htons(asi.TargetPort);
//开始循环
while(1)
{
  printf("\n\n************Udp2Udp Start new**************\n\n");
  _DelSock(s[0]);
  //创建一个UDP socket
  s[0]=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
  if(s[0]==INVALID_SOCKET)
  {
   ShowError("\nUdp2Udp:Create UDP socket");
   Sleep(5000);
   continue;
  }
  _AddSock(s[0]);
  //bind UDP socket
  iRet=bind(s[0],(struct sockaddr *)&UDPLocal,sizeof(UDPLocal));
  if(iRet == SOCKET_ERROR)
  {
   printf("\nUdp2Udp:Bind UDP port %d failed.",asi.LocalPort);
   Sleep(5000);
   continue;
  }
  else
   printf("\nUdp2Udp:Bind UDP port %d ok.",asi.LocalPort);

//  DWORD threadid=GetCurrentThreadId();
  struct sockaddr_in from;
  int dwSize=sizeof(from);
  char incomingbuff[maxsize];
  int read = 1;
  while(read  >0)
  {
   read=recvfrom(s[0],incomingbuff,maxsize,0,(SOCKADDR *)&from,&dwSize);
   if(read <=0  ) break;
   s[1] = udpsvrGetSock1(from) ;
   if(s[1] == 0)
   {
    //创建一个UDP socket
    s[1]=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
    if(s[1]==INVALID_SOCKET)
    {
     ShowError("\nTcp2Udp:Create UDP socket");
     Sleep(5000);
     continue;
    }
    BOOL bindok = FALSE;
    int LocalTmpPort = asi.LocalTmpPort;
    if(LocalTmpPort<1) LocalTmpPort = 4000;
    while(LocalTmpPort <65535)
    {
     //监听本地UDP port的地址结构
     UDPLocal.sin_family=AF_INET;
     UDPLocal.sin_addr.s_addr=INADDR_ANY;
     UDPLocal.sin_port=htons(LocalTmpPort);
     //bind UDP socket
     iRet=bind(s[1],(struct sockaddr *)&UDPLocal,sizeof(UDPLocal));
     if(iRet == SOCKET_ERROR)
     {
      printf("\nTcp2Udp:Bind UDP port %d failed.",LocalTmpPort);
      LocalTmpPort ++ ;
      Sleep(50);
      continue;
     }
     else
     {
      printf("\nTcp2Udp:Bind UDP port %d ok.",LocalTmpPort);
      bindok = TRUE;
      break;
     }
    }
    if(!bindok)
    {
     _DelSock(s[0]);
     _DelSock(s[1]);
     Sleep(5000);
     continue;
    }

    DATAREDIRDPARAM* ptdataredird = new DATAREDIRDPARAM;
    ptdataredird->sock[0] = s[0];//udp
    ptdataredird->sock[1] = s[1];//udp
    memcpy(&ptdataredird->sinudp ,&from,sizeof(sockaddr_in));
    ptdataredird->sinudpisfilled = TRUE;
    udpsvrAddDataRedird(ptdataredird);
    DATAREDIRDPARAM* ptdataredird2 = new DATAREDIRDPARAM;
    memcpy(ptdataredird2,ptdataredird,sizeof(DATAREDIRDPARAM));
    DWORD threadid;
    HANDLE htcp2udpThread = CreateThread(NULL,0,u2uwaitthread,(LPVOID)ptdataredird2,NULL,&threadid);
    CloseHandle(htcp2udpThread);
   }
   printf("\ntUdp2Tcp: recvfrom %s:%d %d bytes.",inet_ntoa(from.sin_addr),ntohs(from.sin_port),read);
   int iUDPRepeat = 3;
   int npos=0;
   while(npos < read)
   {
    int nsendcount=sendto(s[1],incomingbuff+npos,read-npos,0,(SOCKADDR *)&Target,sizeof(Target));
    if(nsendcount == SOCKET_ERROR)
    {
     ShowError("sendto");
     //重复发送次数自减一
     if((iUDPRepeat--)>0)
     {
      printf("\nUDP2UDP Try %d times to send.",iUDPRepeat);
      continue;
     }
    }
    if(nsendcount <= 0 ) return 0;
    printf("\nUDP2UDP:sendto %s:%d %d bytes.",inet_ntoa(Target.sin_addr),ntohs(Target.sin_port),nsendcount);
    npos += nsendcount;
   }
  }
  udpsvrDelAllDataRedird(s[0]);
  printf("\n\n**************OK!Udp2Tcp do next******************\n\n");
}//end of while
return 0;
}
//监护线程
DWORD WINAPI u2uwaitthread(LPVOID lpvoid)
{
DATAREDIRDPARAM* pdrp = (DATAREDIRDPARAM*)lpvoid;
HANDLE hThread;
DWORD id;
hThread = CreateThread(NULL,0,udp2udp,(LPVOID)pdrp,NULL,&id);
_AddThread(hThread);
DWORD  waiter;
waiter = WaitForSingleObject(hThread,INFINITE);
udpsvrDelDataRedird(pdrp->sock[1]);
_DelThread(hThread);
printf("\nUdp2Tcp: Socket closed.\n");
delete pdrp;
ExitThread(0);
return 0;
}
//
//UDP socket数据转发函数，从s[0]接收数据，转发到s[1]
//
DWORD WINAPI udp2udp(LPVOID lpvoid)
{
DATAREDIRDPARAM *tudp = (DATAREDIRDPARAM*)lpvoid;
SOCKET *s = tudp->sock;

DWORD threadid=GetCurrentThreadId();
printf("\n***New UDP2UDP Thread %d recvfrom %d sendto %d.\n",threadid,s[1],s[0]);

struct sockaddr_in from;
int dwSize=sizeof(from);
int iUDPRepeat=3;//UDP发送失败后重复的次数

char incomingbuff[maxsize];
int read = 1;
while(read  >0)
{
  read=recvfrom(s[1],incomingbuff,maxsize,0,(SOCKADDR *)&from,&dwSize);
  if(read <=0  ) break;
  printf("\nUDP2UDP[%d] recvfrom %s:%d %d bytes.",threadid,inet_ntoa(from.sin_addr),ntohs(from.sin_port),read);
  iUDPRepeat = 3;
  int npos=0;
  while(npos < read)
  {
   int nsendcount=sendto(s[0],incomingbuff+npos,read-npos,0,(SOCKADDR *)&tudp->sinudp,sizeof(tudp->sinudp));
   if(nsendcount == SOCKET_ERROR)
   {
    ShowError("sendto");
    //重复发送次数自减一
    if((iUDPRepeat--)>0)
    {
     printf("\nUDP2UDP Try %d times to send.",iUDPRepeat);
     continue;
    }
   }
   if(nsendcount <= 0 ) return 0;
   printf("\nUDP2UDP[%d] sendto %s:%d %d bytes.",threadid,inet_ntoa(tudp->sinudp.sin_addr),ntohs(tudp->sinudp.sin_port),nsendcount);
   npos += nsendcount;
  }
}
printf("\nUDP2UDP Thread %d LastError %d",threadid,GetLastError());
return 0;
}