InterfacesWindows.cpp

#include "SoapyNetSDR.hpp"
#include <winsock2.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <stdlib.h>

// Link with Iphlpapi.lib
#pragma comment(lib, "IPHLPAPI.lib")

#define WORKING_BUFFER_SIZE 15000
#define MAX_TRIES 3

#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))

#if (_WIN32_WINNT < 0x0501)   /* WIN2000-SP1. network 169.254/16 */
#define IN4_IS_ADDR_LINKLOCAL(ip)   ((ip)->S_un.S_un_b.s_b1 == 169 && (ip)->S_un.S_un_b.s_b2 == 254)
#else
#include <mstcpip.h>
#endif

std::vector<interfaceInformation> interfaceList()
{
    std::vector<interfaceInformation> list;

    //nothing but simplicity https://msdn.microsoft.com/en-us/library/aa365915.aspx
    DWORD dwSize = 0;
    DWORD dwRetVal = 0;

    unsigned int i = 0;

    // Set the flags to pass to GetAdaptersAddresses
    ULONG flags = GAA_FLAG_INCLUDE_PREFIX;

    // default to unspecified address family (both)
    ULONG family = AF_UNSPEC;

    LPVOID lpMsgBuf = NULL;

    PIP_ADAPTER_ADDRESSES pAddresses = NULL;
    ULONG outBufLen = 0;
    ULONG Iterations = 0;

    PIP_ADAPTER_ADDRESSES pCurrAddresses = NULL;

    // Allocate a 15 KB buffer to start with.
    outBufLen = WORKING_BUFFER_SIZE;

    do {

        pAddresses = (IP_ADAPTER_ADDRESSES *) MALLOC(outBufLen);
        if (pAddresses == NULL) {
            printf
                ("Memory allocation failed for IP_ADAPTER_ADDRESSES struct\n");
            return list;
        }

        dwRetVal =
            GetAdaptersAddresses(family, flags, NULL, pAddresses, &outBufLen);

        if (dwRetVal == ERROR_BUFFER_OVERFLOW) {
            FREE(pAddresses);
            pAddresses = NULL;
        } else {
            break;
        }

        Iterations++;

    } while ((dwRetVal == ERROR_BUFFER_OVERFLOW) && (Iterations < MAX_TRIES));

    if (dwRetVal == NO_ERROR) {
        // If successful, output some information from the data we received
        pCurrAddresses = pAddresses;
        while (pCurrAddresses) {

            interfaceInformation ifAddr;
            ifAddr.name = pCurrAddresses->AdapterName;
            
            if (pCurrAddresses->OperStatus != IfOperStatusUp)
               continue;   // Ignore adapters not UP

            for (auto addr_i = pCurrAddresses->FirstUnicastAddress; addr_i != NULL; addr_i = addr_i->Next)
            {
                const auto a = addr_i->Address.lpSockaddr;
                const auto sa = (struct sockaddr_in *)a;
                
                if (a->sa_family != AF_INET) continue; //just IPv4
                
                // we do no want a link-local address; we cannot bind to it. And there is no-one there
                if (IN4_IS_ADDR_LINKLOCAL(&sa->sin_addr))
                   continue;
                
                char buf[INET_ADDRSTRLEN];
                inet_ntop(a->sa_family, &(sa->sin_addr), buf, sizeof(buf));
                //extract broadcast address for this interface
                ULONG subnet = 0;
                ConvertLengthToIpv4Mask(addr_i->OnLinkPrefixLength, &subnet);
                ifAddr.address = buf;
                sa->sin_addr.s_addr &= subnet;
                sa->sin_addr.s_addr |= ~subnet;
                inet_ntop(a->sa_family, &(sa->sin_addr), buf, sizeof(buf));
                ifAddr.broadcast = buf;
                list.push_back(ifAddr);
            }

            pCurrAddresses = pCurrAddresses->Next;
        }
    } else {
        printf("Call to GetAdaptersAddresses failed with error: %d\n",
               dwRetVal);
        if (dwRetVal == ERROR_NO_DATA)
            printf("\tNo addresses were found for the requested parameters\n");
        else {

            if (FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                    FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, 
                    NULL, dwRetVal, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),   
                    // Default language
                    (LPTSTR) & lpMsgBuf, 0, NULL)) {
                printf("\tError: %s", (const char *)lpMsgBuf);
                LocalFree(lpMsgBuf);
                if (pAddresses)
                    FREE(pAddresses);
                return list;
            }
        }
    }

    if (pAddresses) {
        FREE(pAddresses);
    }

    return list;
}