获取本机TCP连接状态信息

转自：https://msdn.microsoft.com/en-us/library/windows/desktop/aa366909(v=vs.85).aspx

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#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_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
");
        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
");
            return 1;
        }
    }
// Make a second call to GetTcpTable to get
// the actual data we require
    if ((dwRetVal = GetTcpTable(pTcpTable, &dwSize, TRUE)) == NO_ERROR) {
        printf("	Number of entries: %d
", (int) pTcpTable->dwNumEntries);
        for (i = 0; i < (int) pTcpTable->dwNumEntries; i++) {
            printf("
	TCP[%d] State: %ld - ", i,
                   pTcpTable->table[i].dwState);
            switch (pTcpTable->table[i].dwState) {
            case MIB_TCP_STATE_CLOSED:
                printf("CLOSED
");
                break;
            case MIB_TCP_STATE_LISTEN:
                printf("LISTEN
");
                break;
            case MIB_TCP_STATE_SYN_SENT:
                printf("SYN-SENT
");
                break;
            case MIB_TCP_STATE_SYN_RCVD:
                printf("SYN-RECEIVED
");
                break;
            case MIB_TCP_STATE_ESTAB:
                printf("ESTABLISHED
");
                break;
            case MIB_TCP_STATE_FIN_WAIT1:
                printf("FIN-WAIT-1
");
                break;
            case MIB_TCP_STATE_FIN_WAIT2:
                printf("FIN-WAIT-2 
");
                break;
            case MIB_TCP_STATE_CLOSE_WAIT:
                printf("CLOSE-WAIT
");
                break;
            case MIB_TCP_STATE_CLOSING:
                printf("CLOSING
");
                break;
            case MIB_TCP_STATE_LAST_ACK:
                printf("LAST-ACK
");
                break;
            case MIB_TCP_STATE_TIME_WAIT:
                printf("TIME-WAIT
");
                break;
            case MIB_TCP_STATE_DELETE_TCB:
                printf("DELETE-TCB
");
                break;
            default:
                printf("UNKNOWN dwState value: %d
", pTcpTable->table[i].dwState);
                break;
            }

            IpAddr.S_un.S_addr = (u_long) pTcpTable->table[i].dwLocalAddr;
            strcpy_s(szLocalAddr, sizeof (szLocalAddr), inet_ntoa(IpAddr));
            printf("	TCP[%d] Local Addr: %s
", i, szLocalAddr);

            printf("	TCP[%d] Local Port: %d 
", i,
                   ntohs((u_short)pTcpTable->table[i].dwLocalPort));

            IpAddr.S_un.S_addr = (u_long) pTcpTable->table[i].dwRemoteAddr;
            strcpy_s(szRemoteAddr, sizeof (szRemoteAddr), inet_ntoa(IpAddr));
            printf("	TCP[%d] Remote Addr: %s
", i, szRemoteAddr);

            printf("	TCP[%d] Remote Port: %d
", i,
                   ntohs((u_short)pTcpTable->table[i].dwRemotePort));
        }
    } else {
        printf("	GetTcpTable failed with %d
", dwRetVal);
        FREE(pTcpTable);
        return 1;
    }

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

    return 0;    
}