Expand Minimize

GetTcpTable function

The GetTcpTable function retrieves the IPv4 TCP connection table.

Syntax


DWORD WINAPI GetTcpTable(
  _Out_    PMIB_TCPTABLE pTcpTable,
  _Inout_  PDWORD pdwSize,
  _In_     BOOL bOrder
);

Parameters

pTcpTable [out]

A pointer to a buffer that receives the TCP connection table as a MIB_TCPTABLE structure.

pdwSize [in, out]

On input, specifies the size in bytes of the buffer pointed to by the pTcpTable parameter.

On output, if the buffer is not large enough to hold the returned connection table, the function sets this parameter equal to the required buffer size in bytes.

On the Windows SDK released for Windows Vista and later, the data type for this parameter is changed to a PULONG which is equivalent to a PDWORD.

bOrder [in]

A Boolean value that specifies whether the TCP connection table should be sorted. If this parameter is TRUE, the table is sorted in the order of:

  1. Local IP address
  2. Local port
  3. Remote IP address
  4. Remote port

Return value

If the function succeeds, the return value is NO_ERROR.

If the function fails, the return value is one of the following error codes.

Return codeDescription
ERROR_INSUFFICIENT_BUFFER

The buffer pointed to by the pTcpTable parameter is not large enough. The required size is returned in the DWORD variable pointed to by the pdwSize parameter.

This error is also returned if the pTcpTable parameter is NULL.

ERROR_INVALID_PARAMETER

The pdwSize parameter is NULL, or GetTcpTable is unable to write to the memory pointed to by the pdwSize parameter.

ERROR_NOT_SUPPORTED

This function is not supported on the operating system in use on the local system.

Other

Use FormatMessage to obtain the message string for the returned error.

 

Remarks

On the Windows SDK released for Windows Vista and later, the return value from the GetTcpTable function is changed to a data type of ULONG which is equivalent to a DWORD.

Examples

The following example retrieves the TCP connection table for IPv4 and prints the state of each connection.


// Need to link with Iphlpapi.lib and Ws2_32.lib
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <stdio.h>

#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_TCPTABLE pTcpTable;
    DWORD dwSize = 0;
    DWORD dwRetVal = 0;

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

    struct in_addr IpAddr;

    int i;

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

    dwSize = sizeof (MIB_TCPTABLE);
// Make an initial call to GetTcpTable to
// get the necessary size into the dwSize variable
    if ((dwRetVal = GetTcpTable(pTcpTable, &dwSize, TRUE)) ==
        ERROR_INSUFFICIENT_BUFFER) {
        FREE(pTcpTable);
        pTcpTable = (MIB_TCPTABLE *) MALLOC(dwSize);
        if (pTcpTable == NULL) {
            printf("Error allocating memory\n");
            return 1;
        }
    }
// Make a second call to GetTcpTable to get
// the actual data we require
    if ((dwRetVal = GetTcpTable(pTcpTable, &dwSize, TRUE)) == NO_ERROR) {
        printf("\tNumber of entries: %d\n", (int) pTcpTable->dwNumEntries);
        for (i = 0; i < (int) pTcpTable->dwNumEntries; i++) {
            IpAddr.S_un.S_addr = (u_long) pTcpTable->table[i].dwLocalAddr;
            strcpy_s(szLocalAddr, sizeof (szLocalAddr), inet_ntoa(IpAddr));
            IpAddr.S_un.S_addr = (u_long) pTcpTable->table[i].dwRemoteAddr;
            strcpy_s(szRemoteAddr, sizeof (szRemoteAddr), inet_ntoa(IpAddr));

            printf("\n\tTCP[%d] State: %ld - ", i,
                   pTcpTable->table[i].dwState);
            switch (pTcpTable->table[i].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;
            }
            printf("\tTCP[%d] Local Addr: %s\n", i, szLocalAddr);
            printf("\tTCP[%d] Local Port: %d \n", i,
                   ntohs((u_short)pTcpTable->table[i].dwLocalPort));
            printf("\tTCP[%d] Remote Addr: %s\n", i, szRemoteAddr);
            printf("\tTCP[%d] Remote Port: %d\n", i,
                   ntohs((u_short)pTcpTable->table[i].dwRemotePort));
        }
    } else {
        printf("\tGetTcpTable failed with %d\n", dwRetVal);
        FREE(pTcpTable);
        return 1;
    }

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

    return 0;    
}



Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Iphlpapi.h

Library

Iphlpapi.lib

DLL

Iphlpapi.dll

See also

GetExtendedTcpTable
GetOwnerModuleFromTcpEntry
GetTcp6Table
GetTcp6Table2
GetTcpStatistics
GetTcpStatisticsEx
GetTcpTable2
MIB_TCPROW
MIB_TCPROW_OWNER_MODULE
MIB_TCPROW_OWNER_PID
MIB_TCPTABLE
MIB_TCPTABLE_OWNER_MODULE
MIB_TCPTABLE_OWNER_PID
SetTcpEntry

 

 

Community Additions

ADD
Show:
© 2014 Microsoft