Retrieving Information Using GetTcpStatistics

The GetTcpStatistics function fills a pointer to an MIB_TCPSTATS structure with information on the TCP protocol statistics for the local computer.

To use GetTcpStatistics

1. Declare some variables that are needed.

   Declare a DWORD variable dwRetVal that will be using for error checking function calls. Declare a pointer to an MIB_TCPSTATS variable called pTCPStats, and allocate memory for the structure. Check that memory could be allocated.

   DWORD dwRetVal = 0;
   PMIB_TCPSTATS pTCPStats;
   
   pTCPStats = (MIB_TCPSTATS *) malloc(sizeof (MIB_TCPSTATS));
   if (pTCPStats == NULL) {
       printf("Error allocating memory\n");
   }
   

2. Call the GetTcpStatistics function with the pTCPStats parameter to retrieve TCP statistics for IPv4 on the local computer. Check for errors and return the error value in the DWORD variable dwRetVal. If an error occurs, the dwRetVal variable can be used for more extensive error checking and reporting.

       if ((dwRetVal = GetTcpStatistics(pTCPStats)) != NO_ERROR) {
           printf("GetTcpStatistics failed with error: %ld\n", dwRetVal);
       } 
   

3. If the call was successful, access the data returned in the MIB_TCPSTATS pointed to by the pTCPStats parameter.

   printf("\tNumber of active opens:  %u\n", pTCPStats->dwActiveOpens);
   printf("\tNumber of passive opens: %u\n", pTCPStats->dwPassiveOpens);
   printf("\tNumber of segments received: %u\n", pTCPStats->dwInSegs);
   printf("\tNumber of segments transmitted: %u\n", pTCPStats->dwOutSegs);
   printf("\tNumber of total connections: %u\n", pTCPStats->dwNumConns);
   

4. Free the memory allocated for the MIB_TCPSTATS structure pointed to by the pTCPStats parameter. This should be done once the application no longer needs the data returned by the pTCPStats parameter.

   if (pTCPStats)
       free(pTCPStats);
   

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