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Winsock and Connection Failures

Posted on 2006-10-30
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Last Modified: 2010-04-01
Hi,

i am trying to get a winsock to retry a connection attemp if it failed the first time.
How can i do this?

//----------------- MY CONNECTION CODE ----------------------------------

  if (::connect(s_, (sockaddr *) &addr, sizeof(sockaddr)))
  {
    error = strerror(WSAGetLastError());
    throw error;
  }

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Question by:cossy74
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6 Comments
 
LVL 30

Expert Comment

by:Axter
ID: 17839540
Have you initialized Winsock? You have to make a call to WSAStartup() before you can use any of the Winsock functions.
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jkr earned 168 total points
ID: 17839544
Well, just like e.g.

//----------------- MY CONNECTION CODE ----------------------------------

#define MAX_TRY_COUNT 42
unsigned unTryCount = 0;

while(unTryCount < MAX_TRY_COUNT)
{
  if (::connect(s_, (sockaddr *) &addr, sizeof(sockaddr)))
  {
    unTryCount++
    Sleep(1000);
  }
}

  if (unTryCount < MAX_TRY_COUNT)
  {
    error = strerror(WSAGetLastError());
    throw error;
  }
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LVL 30

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by:Axter
Axter earned 166 total points
ID: 17839545
Example:
     int nErr = 0;
     WORD wVersionRequested;
     WSADATA wsaData;

     //********* Initializing windows socket library ******************
     wVersionRequested = MAKEWORD(1,1);
     if(nErr = WSAStartup(   wVersionRequested,  &wsaData))
    {  
       printf("\nunable to initialize WINSOCK, reason: %d\n",nErr);
       exit(0);
    }
     else printf("WSAStartup OK....!!!\n");
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LVL 39

Assisted Solution

by:itsmeandnobodyelse
itsmeandnobodyelse earned 166 total points
ID: 17840571
Don't think strerror can show socket errors. From my docs it shows errors from errno only.

You may write your own errortext function or take that:

std::string getErrorDesc ()
{
    // on NT we have no chance to get a error description, so we
    // have to hardcode the string. Yuck!
    int code = WSAGetLastError ();
    std::string msg = string ("NT socket error #") + string (code);
    switch (code) {
      case WSAEINVAL:             msg = "invalid parameter";                 break;
      case WSASYSNOTREADY:       msg = "system not ready";                 break;
      case WSAVERNOTSUPPORTED:    msg = "winsock version not supported";           break;
      case WSANOTINITIALISED:          msg = "winsock module not initialized";     break;
      case WSAENETDOWN:       msg = "network is down";                 break;
      case WSAHOST_NOT_FOUND:      msg = "host not found";                 break;
      case WSATRY_AGAIN:       msg = "temporary error - try again";           break;
      case WSANO_RECOVERY:       msg = "fatal network error";                 break;
      case WSANO_DATA:                       msg = "host has no address";                 break;
      case WSAENETRESET:       msg = "connection dropped - must be reset"; break;
      case WSAENOBUFS:                       msg = "buffer deadlock - windows error";    break;
      case WSAECONNABORTED:       msg = "connection was aborted";           break;
      case WSAECONNRESET:       msg = "connection was reset by remote side";break;
      case WSAEADDRINUSE:       msg = "address is already in use";           break;
      case WSAEADDRNOTAVAIL:       msg = "address is unavailable";                           break;
      case WSAENETUNREACH:       msg = "network is unreachable";           break;
      case WSAETIMEDOUT:       msg = "connection timed out";                 break;
      case WSAECONNREFUSED:       msg = "connection refused";                 break;
      case WSAEHOSTDOWN:       msg = "host is down";                           break;
      case WSAEHOSTUNREACH:       msg = "host is unreachable";                 break;
    }
    return msg;
}

Regards, Alex

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