MIB_TCP6ROW structure (tcpmib.h)

The MIB_TCP6ROW structure contains information that describes an IPv6 TCP connection.

Syntax

typedef struct _MIB_TCP6ROW {
  MIB_TCP_STATE State;
  IN6_ADDR      LocalAddr;
  DWORD         dwLocalScopeId;
  DWORD         dwLocalPort;
  IN6_ADDR      RemoteAddr;
  DWORD         dwRemoteScopeId;
  DWORD         dwRemotePort;
} MIB_TCP6ROW, *PMIB_TCP6ROW;

Members

State

Type: MIB_TCP_STATE

The state of the TCP connection. This member can be one of the values from the MIB_TCP_STATE enumeration type defined in the Tcpmib.h header file.

LocalAddr

Type: IN6_ADDR

The local IPv6 address for the TCP connection on the local computer. A value of zero indicates the listener can accept a connection on any interface.

dwLocalScopeId

Type: DWORD

The local scope ID for the TCP connection on the local computer.

dwLocalPort

Type: DWORD

The local port number in network byte order for the TCP connection on the local computer.

The maximum size of an IP port number is 16 bits, so only the lower 16 bits should be used. The upper 16 bits may contain uninitialized data.

RemoteAddr

Type: IN6_ADDR

The IPv6 address for the TCP connection on the remote computer. When the State member is MIB_TCP_STATE_LISTEN, this value has no meaning.

dwRemoteScopeId

Type: DWORD

The remote scope ID for the TCP connection on the remote computer. When the State member is MIB_TCP_STATE_LISTEN, this value has no meaning.

dwRemotePort

Type: DWORD

The remote port number in network byte order for the TCP connection on the remote computer. When the State member is MIB_TCP_STATE_LISTEN, this value has no meaning.

The maximum size of an IP port number is 16 bits, so only the lower 16 bits should be used. The upper 16 bits may contain uninitialized data.

Remarks

The MIB_TCP6ROW 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 State member indicates the state of the TCP entry in a TCP state diagram. A TCP connection progresses through a series of states during its lifetime. The states are: LISTEN, SYN-SENT, SYN-RECEIVED, ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT, and the fictional state CLOSED. The CLOSED state is fictional because it represents the state when there is no Transmission Control Block, and therefore, no connection. The TCP protocol is described in RFC 793. For more information, see http://www.ietf.org/rfc/rfc793.txt.

The dwLocalPort, and dwRemotePort members are in network byte order. In order to use the dwLocalPort or dwRemotePort members, the ntohs or inet_ntoa functions in Windows Sockets or similar functions may be needed.

The dwLocalScopeId, and dwRemoteScopeId members are in network byte order. In order to use the dwLocalScopeId or dwRemoteScopeId members, the ntohl or inet_ntoa functions in Windows Sockets or similar functions may be needed.

The LocalAddr and RemoteAddr members are stored in in6_addr structures. The RtlIpv6AddressToString or RtlIpv6AddressToStringEx functions may be used to convert the IPv6 address in the LocalAddr or RemoteAddr members to a string without loading the Windows Sockets DLL.

Examples

The following example retrieves the TCP connection table for IPv6 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

See also

GetTcp6Table

MIB_TCP6TABLE

MIB_TCPROW

MIB_TCPTABLE

RtlIpv6AddressToString

RtlIpv6AddressToStringEx

in6_addr

inet_ntoa

ntohl

ntohs