MIB_TCP6TABLE structure (tcpmib.h)

Article
02/22/2024

The MIB_TCP6TABLE structure contains a table of TCP connections for IPv6 on the local computer.

Syntax

typedef struct _MIB_TCP6TABLE {
  DWORD       dwNumEntries;
  MIB_TCP6ROW table[ANY_SIZE];
} MIB_TCP6TABLE, *PMIB_TCP6TABLE;

Members

dwNumEntries

A value that specifies the number of TCP connections in the array.

table[ANY_SIZE]

An array of MIB_TCP6ROW structures containing TCP connection entries.

Remarks

The MIB_TCP6TABLE structure is defined on Windows Vista and later.

The GetTcp6Table function retrieves the IPv6 TCP connection table on the local computer and returns this information in a MIB_TCP6TABLE structure.

An array of MIB_TCP6ROW structures are contained in the MIB_TCP6TABLE structure.

The MIB_TCP6TABLE structure may contain padding for alignment between the dwNumEntries member and the first MIB_TCP6ROW array entry in the table member. Padding for alignment may also be present between the MIB_TCP6ROW array entries in the table member. Any access to a MIB_TCP6ROW array entry should assume padding may exist.

Examples

The following example retrieves the TCP connection table for IPv6 as a MIB_TCP6TABLE structure and prints the state of each connection represented as a MIB_TCP6ROW structure.

#define UNICODE 1

#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 wmain()
{

    // Declare and initialize variables
    PMIB_TCP6TABLE pTcpTable;
    DWORD dwSize = 0;
    DWORD dwRetVal = 0;

    wchar_t ipstringbuffer[46];
    
    int i;

    pTcpTable = (MIB_TCP6TABLE *) MALLOC(sizeof (MIB_TCP6TABLE));
    if (pTcpTable == NULL) {
        wprintf(L"Error allocating memory\n");
        return 1;
    }

    dwSize = sizeof (MIB_TCP6TABLE);
// Make an initial call to GetTcp6Table to
// get the necessary size into the dwSize variable
    if ((dwRetVal = GetTcp6Table(pTcpTable, &dwSize, TRUE)) ==
        ERROR_INSUFFICIENT_BUFFER) {
        FREE(pTcpTable);
        pTcpTable = (MIB_TCP6TABLE *) MALLOC(dwSize);
        if (pTcpTable == NULL) {
            wprintf(L"Error allocating memory\n");
            return 1;
        }
    }
// Make a second call to GetTcp6Table to get
// the actual data we require
    if ((dwRetVal = GetTcp6Table(pTcpTable, &dwSize, TRUE)) == NO_ERROR) {
        wprintf(L"\tNumber of entries: %d\n", (int) pTcpTable->dwNumEntries);
        for (i = 0; i < (int) pTcpTable->dwNumEntries; i++) {
            wprintf(L"\n\tTCP[%d] State: %ld - ", i,
                   pTcpTable->table[i].State);
            switch (pTcpTable->table[i].State) {
            case MIB_TCP_STATE_CLOSED:
                wprintf(L"CLOSED\n");
                break;
            case MIB_TCP_STATE_LISTEN:
                wprintf(L"LISTEN\n");
                break;
            case MIB_TCP_STATE_SYN_SENT:
                wprintf(L"SYN-SENT\n");
                break;
            case MIB_TCP_STATE_SYN_RCVD:
                wprintf(L"SYN-RECEIVED\n");
                break;
            case MIB_TCP_STATE_ESTAB:
                wprintf(L"ESTABLISHED\n");
                break;
            case MIB_TCP_STATE_FIN_WAIT1:
                wprintf(L"FIN-WAIT-1\n");
                break;
            case MIB_TCP_STATE_FIN_WAIT2:
                wprintf(L"FIN-WAIT-2 \n");
                break;
            case MIB_TCP_STATE_CLOSE_WAIT:
                wprintf(L"CLOSE-WAIT\n");
                break;
            case MIB_TCP_STATE_CLOSING:
                wprintf(L"CLOSING\n");
                break;
            case MIB_TCP_STATE_LAST_ACK:
                wprintf(L"LAST-ACK\n");
                break;
            case MIB_TCP_STATE_TIME_WAIT:
                wprintf(L"TIME-WAIT\n");
                break;
            case MIB_TCP_STATE_DELETE_TCB:
                wprintf(L"DELETE-TCB\n");
                break;
            default:
                wprintf(L"UNKNOWN dwState value\n");
                break;
            }

            if (InetNtop(AF_INET6, &pTcpTable->table[i].LocalAddr, ipstringbuffer, 46) == NULL)
                wprintf(L"  InetNtop function failed for local IPv6 address\n");
            else     
                wprintf(L"\tTCP[%d] Local Addr: %s\n", i, ipstringbuffer);
            wprintf(L"\tTCP[%d] Local Scope ID: %d \n", i,
                   ntohl (pTcpTable->table[i].dwLocalScopeId));
            wprintf(L"\tTCP[%d] Local Port: %d \n", i,
                   ntohs((u_short)pTcpTable->table[i].dwLocalPort));

            if (InetNtop(AF_INET6, &pTcpTable->table[i].RemoteAddr, ipstringbuffer, 46) == NULL)
                wprintf(L"  InetNtop function failed for remote IPv6 address\n");
            else     
                wprintf(L"\tTCP[%d] Remote Addr: %s\n", i, ipstringbuffer);
            wprintf(L"\tTCP[%d] Remote Scope ID: %d \n", i,
                   ntohl(pTcpTable->table[i].dwRemoteScopeId));
            wprintf(L"\tTCP[%d] Remote Port: %d\n", i,
                   ntohs((u_short)pTcpTable->table[i].dwRemotePort));
        }
    } else {
        wprintf(L"\tGetTcp6Table failed with %d\n", dwRetVal);
        FREE(pTcpTable);
        return 1;
    }

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

    return 0;    
}

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Header	tcpmib.h (include Iphlpapi.h)