Print network connection state

GetTcpTable2.cpp

#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <stdio.h>

// Need to link with Iphlpapi.lib and Ws2_32.lib
#pragma comment(lib, "iphlpapi.lib")
#pragma comment(lib, "ws2_32.lib")

#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))
/* Note: could also use malloc() and free() */

int main() {

  // Declare and initialize variables
  PMIB_TCPTABLE2 pTcpTable = NULL;
  ULONG ulSize = 0;
  DWORD dwRetVal = 0;

  char szLocalAddr[128];
  char szRemoteAddr[128];

  struct in_addr IpAddr;

  // Make an initial call to GetTcpTable2 to
  // get the necessary size into the ulSize variable
  dwRetVal = GetTcpTable2(pTcpTable, &ulSize, TRUE);
  if (dwRetVal == ERROR_INSUFFICIENT_BUFFER) {
    pTcpTable = (MIB_TCPTABLE2 *)MALLOC(ulSize);
    if (pTcpTable == NULL) {
      printf("Error allocating memory\n");
      return 1;
    }
  }
  // Make a second call to GetTcpTable2 to get
  // the actual data we require
  if ((dwRetVal = GetTcpTable2(pTcpTable, &ulSize, TRUE)) == NO_ERROR) {
    printf("\tNumber of entries: %d\n", (int)pTcpTable->dwNumEntries);
    for (int idx = 0; idx < (int)pTcpTable->dwNumEntries; idx++) {
      printf("\n\tTCP[%d] State: %ld - ", idx, pTcpTable->table[idx].dwState);
      switch (pTcpTable->table[idx].dwState) {
        case MIB_TCP_STATE_CLOSED:
          printf("CLOSED\n");
          break;
        case MIB_TCP_STATE_LISTEN:
          printf("LISTEN\n");
          break;
        case MIB_TCP_STATE_SYN_SENT:
          printf("SYN-SENT\n");
          break;
        case MIB_TCP_STATE_SYN_RCVD:
          printf("SYN-RECEIVED\n");
          break;
        case MIB_TCP_STATE_ESTAB:
          printf("ESTABLISHED\n");
          break;
        case MIB_TCP_STATE_FIN_WAIT1:
          printf("FIN-WAIT-1\n");
          break;
        case MIB_TCP_STATE_FIN_WAIT2:
          printf("FIN-WAIT-2 \n");
          break;
        case MIB_TCP_STATE_CLOSE_WAIT:
          printf("CLOSE-WAIT\n");
          break;
        case MIB_TCP_STATE_CLOSING:
          printf("CLOSING\n");
          break;
        case MIB_TCP_STATE_LAST_ACK:
          printf("LAST-ACK\n");
          break;
        case MIB_TCP_STATE_TIME_WAIT:
          printf("TIME-WAIT\n");
          break;
        case MIB_TCP_STATE_DELETE_TCB:
          printf("DELETE-TCB\n");
          break;
        default:
          printf("UNKNOWN dwState value\n");
          break;
      }
      IpAddr.S_un.S_addr = (u_long)pTcpTable->table[idx].dwLocalAddr;
      strcpy_s(szLocalAddr, sizeof(szLocalAddr), inet_ntoa(IpAddr));
      printf("\tTCP[%d] Local Addr: %s\n", idx, szLocalAddr);
      printf("\tTCP[%d] Local Port: %d \n", idx,
             ntohs((u_short)pTcpTable->table[idx].dwLocalPort));

      IpAddr.S_un.S_addr = (u_long)pTcpTable->table[idx].dwRemoteAddr;
      strcpy_s(szRemoteAddr, sizeof(szRemoteAddr), inet_ntoa(IpAddr));
      printf("\tTCP[%d] Remote Addr: %s\n", idx, szRemoteAddr);
      printf("\tTCP[%d] Remote Port: %d\n", idx,
             ntohs((u_short)pTcpTable->table[idx].dwRemotePort));
      printf("\tTCP[%d] Owning PID: %d\n", idx,
             pTcpTable->table[idx].dwOwningPid);
      printf("\tTCP[%d] Offload State: %ld - ", idx,
             pTcpTable->table[idx].dwOffloadState);
      switch (pTcpTable->table[idx].dwOffloadState) {
        case TcpConnectionOffloadStateInHost:
          printf("Owned by the network stack and not offloaded \n");
          break;
        case TcpConnectionOffloadStateOffloading:
          printf("In the process of being offloaded\n");
          break;
        case TcpConnectionOffloadStateOffloaded:
          printf("Offloaded to the network interface control\n");
          break;
        case TcpConnectionOffloadStateUploading:
          printf("In the process of being uploaded back to the network stack\n");
          break;
        default:
          printf("UNKNOWN Offload state value\n");
          break;
      }
    }
  } else {
    printf("\tGetTcpTable2 failed with %d\n", dwRetVal);
    FREE(pTcpTable);
    return 1;
  }

  if (pTcpTable != NULL) {
    FREE(pTcpTable);
    pTcpTable = NULL;
  }

  return 0;
}