kb4038779 - problem with getnameinfo()

The following program stopped working after this patch (kb4038779) had been installed in Windows 7 Pro x64 SP1:


// gethostname.c :
//
// Testprogramm zum Testen der getnameinfo-Funktion unter Windows (7,10, Windows Server 20xx)
// CPK

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#include <sys/types.h>

typedef unsigned int SOCKET;

#include <Winsock2.h>
#include <ws2tcpip.h>

void usage(void);
int exit(int);
#define MAXHOSTNAMELEN 512

static char hostinfo[NI_MAXHOST];
static char hostname[MAXHOSTNAMELEN];

int main(int argc, char *argv[])
{
int result,err;
int wsreturn;
static char tmpstring[1024];
WORD wVersionRequested;
WSADATA wsaData;
SOCKADDR_IN sa;
sa.sin_family=AF_INET;
wVersionRequested = MAKEWORD( 2, 2 );

err = WSAStartup( wVersionRequested , &wsaData );
if ( err != 0 ) {
/* Tell the user that we couldn't find a usable */
/* winsock.dll. */
printf("server: couldn't find a Winsock 2.2!\n"),exit(3);
}
if(argc !=2)
usage();

inet_pton(AF_INET,argv[1], &(sa.sin_addr));

result=getnameinfo((struct sockaddr *)&sa,
sizeof (sa),hostinfo,NI_MAXHOST,NULL,0,0);
wsreturn=WSAGetLastError();
if(wsreturn!=0)
printf("WSockError=%d\n",wsreturn);
printf("CLIENT: ip=[%s] hostinfo=[%s] result=%d wsreturn=%d\n", argv[1],hostinfo,result,wsreturn);

return 0;

}
void usage() {
printf("gethostname <IP>\nz.B. gethostname 10.172.10.35\n"),exit(1);
}


Using it, gives the following result:


C:\>gethostname 172.27.1.252 ... a few (10) seconds of waiting here

CLIENT: ip=[172.27.1.252] hostinfo=[172.27.1.252] result=0 wsreturn=0


Without the patch


C:\>gethostname 172.27.1.252 ... no waiting here, immediate return

CLIENT: ip=[172.27.1.252] hostinfo=[some.host.domain] result=0 wsreturn=0



After a while the behaviour changed again to that of the situation without the patch.