I ran into a problem trying to test an application under Application Verifier with Page Heap on. It turns out that gethostbyname API always fails even for legit host names like "localhost". The problem reproduces on every Win-7 or Server 2008 R2 I tried even for a very simple test applications using gethostbyname.
Repro steps: in appverifier check "page heap" and "UseLFGGuard..." checkboxes, run any app using gethostbyname(..).
Example of application code (prints "127.0.0.1" when appverifier is off, "getaddrinfo failed" when appverifier is on):
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>
#include <windows.h>
#pragma comment(lib, "ws2_32.lib")
void
Exercise()
{
int i = 0;
struct hostent *remoteHost;
struct in_addr addr;
remoteHost = gethostbyname("localhost");
if (remoteHost == NULL)
{
printf("gethostbyname(localhost) failed\n");
}
else
{
if (remoteHost->h_addrtype == AF_INET)
{
i=0;
while (remoteHost->h_addr_list[i] != 0)
{
addr.s_addr = *(u_long *) remoteHost->h_addr_list[i++];
printf("\tIP Address #%d: %s\n", i, inet_ntoa(addr));
}
}
else
{
printf("unexpected address type\n");
}
}
}
int
main()
{
WSADATA wsaData;
int iResult;
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0)
{
printf("WSAStartup failed: %d\n", iResult);
return 1;
}
for(int i=0; i<1000; i++)
{
Exercise();
Sleep(1000);
}
return 0;
}
The most unusual thing is that I could not find anything in the internet. Is this a known problem? Any workarounds?
Related
I am testing getnameinfo on Windows 11 with the following simple code. The network device name shows up in the router device table and also with a network scanner app on my phone.
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>
// link with ws2_32.lib
#pragma comment(lib, "Ws2_32.lib")
int __cdecl main(int argc, char** argv)
{
//-----------------------------------------
// Declare and initialize variables
WSADATA wsaData = { 0 };
int iResult = 0;
DWORD dwRetval;
struct sockaddr_in saGNI;
char hostname[NI_MAXHOST];
char servInfo[NI_MAXSERV];
u_short port = 27015;
// Validate the parameters
if (argc != 2) {
printf("usage: %s IPv4 address\n", argv[0]);
printf(" to return hostname\n");
printf(" %s 127.0.0.1\n", argv[0]);
return 1;
}
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0) {
printf("WSAStartup failed: %d\n", iResult);
return 1;
}
//-----------------------------------------
// Set up sockaddr_in structure which is passed
// to the getnameinfo function
saGNI.sin_family = AF_INET;
saGNI.sin_addr.s_addr = inet_addr(argv[1]);
saGNI.sin_port = htons(port);
//-----------------------------------------
// Call getnameinfo
dwRetval = getnameinfo((struct sockaddr*)&saGNI,
sizeof(struct sockaddr),
hostname,
NI_MAXHOST, servInfo, NI_MAXSERV, NI_NAMEREQD);
if (dwRetval != 0) {
printf("getnameinfo failed with error # %ld\n", WSAGetLastError());
return 1;
}
else {
printf("getnameinfo returned hostname = %s\n", hostname);
return 0;
}
}
The function does not return a host name. Is there an mistake in the above code or is there a better/more reliable way of getting the name of the network device?
I'm trying make simple code call an enclave field and just add 1.
I'm reference this site : https://software.intel.com/en-us/articles/getting-started-with-sgx-sdk-f...
After it finishes, there is no error, but the enclave code is not working.
Here is my project.zip code with Visual Studio 2017 https://drive.google.com/open?id=13trTAamhNWaz2Q2BRDtUFP5qCX8Syyuc
app.cpp
#include <stdio.h>
#include <Windows.h>
#include <tchar.h>
#include "sgx_urts.h"
#include "Enclave1_u.h"
#define ENCLAVE_FILE _T("Enclave1.signed.dll")
int main() {
int a = 1;
int i = 0;
sgx_enclave_id_t eid;
sgx_status_t ret = SGX_SUCCESS;
sgx_launch_token_t token = { 0 };
int updated = 0;
ret = sgx_create_enclave(ENCLAVE_FILE, SGX_DEBUG_FLAG, &token, &updated, &eid, NULL);
if (ret != SGX_SUCCESS)
{
printf("APP error%#x, failed to create enclave. \n", ret);
return -1;
}
int *ptr = &a;
printf("%d\n",*ptr);
while (i<5) {
foo(eid, ptr);
printf("%d\n", *ptr);
Sleep(1000);
i++;
}
if (SGX_SUCCESS != sgx_destroy_enclave(eid))
return -1;
}
Enclave1.edl
enclave {
from "sgx_tstdc.edl" import *;
trusted {
/* define ECALLs here. */
public void foo([in, size = 4]int *ptr);
};
untrusted {
/* define OCALLs here. */
};
};
Enclave1.cpp
#include "Enclave1_t.h"
#include "sgx_trts.h"
#include <string.h>
void foo(int *ptr)
{
if (*ptr == 1) *ptr == 43971;
*ptr += 1;
}
I expected it to print:
43971, 43972, 43973, 43974 .....
But the result is:
1, 1, 1, .........
What did I miss?
i solved this problem.
foo needs [out] instad of [in] so Enclave1.edl should
enclave { from "sgx_tstdc.edl" import *;
trusted {
/* define ECALLs here. */
public void foo([out, size = 4]int *ptr);
};
untrusted {
/* define OCALLs here. */
};
};
project1.signed.dll file is not updated on debug folder. so i try rebuild project and it updated. I'm realized this file is enclave field itself
IF state grammar is wrong. it should be if (*ptr == 1) *ptr = 43971;
After performing the command "insmod demo_device" the modules listed in /proc/modules
**demo_device 2528 0 - Live 0xe02da000**
fp_indicators 5072 1 - Live 0xe02d2000 (P)
screader 22672 1 - Live 0xe02c5000 (P)
icamdescrambler 12912 0 - Live 0xe02b2000 (P)
icamemmfilter 16208 0 - Live 0xe02a4000 (P)
icamecmfilter 14992 0 - Live 0xe0294000 (P)
but "(P)" is not avail after that.
After firing the command cat /proc/devices the device "demo_device" is not listed there.
So my question is that: what (P) stands in (cat /proc/modules) and what could be the reason that the device is not listed in (cat /proc/devices).
Thanks in Advance !!
The source code is as:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/version.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <asm/uaccess.h>
#include "query_ioctl.h"
#define FIRST_MINOR 0
#define MINOR_CNT 1
static dev_t dev;
static struct cdev c_dev;
static struct class *cl;
static int status = 1, dignity = 3, ego = 5;
static int my_open(struct inode *i, struct file *f)
{
return 0;
}
static int my_close(struct inode *i, struct file *f)
{
return 0;
}
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,35))
static int my_ioctl(struct inode *i, struct file *f, unsigned int cmd, unsigned long arg)
#else
static long my_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
#endif
{
query_arg_t q;
switch (cmd)
{
case QUERY_GET_VARIABLES:
q.status = status;
q.dignity = dignity;
q.ego = ego;
if (copy_to_user((query_arg_t *)arg, &q, sizeof(query_arg_t)))
{
return -EACCES;
}
break;
case QUERY_CLR_VARIABLES:
status = 0;
dignity = 0;
ego = 0;
break;
case QUERY_SET_VARIABLES:
if (copy_from_user(&q, (query_arg_t *)arg, sizeof(query_arg_t)))
{
return -EACCES;
}
status = q.status;
dignity = q.dignity;
ego = q.ego;
break;
default:
return -EINVAL;
}
return 0;
}
static struct file_operations query_fops =
{
.owner = THIS_MODULE,
.open = my_open,
.release = my_close,
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,35))
.ioctl = my_ioctl
#else
.unlocked_ioctl = my_ioctl
#endif
};
static int __init query_ioctl_init(void)
{
int ret;
struct device *dev_ret;
printk("Before calling alloc\n");
dev=150;
if ((ret = register_chrdev_region(dev, MINOR_CNT, "demo_device")))
{
return ret;
}
else if((ret = alloc_chrdev_region(&dev,0,MINOR_CNT,"demo_device")))
{
return ret;
}
printk("After alloc %d %d\n",ret,dev);
cdev_init(&c_dev, &query_fops);
if ((ret = cdev_add(&c_dev, dev, MINOR_CNT)) < 0)
{
return ret;
}
printk("After cdev_add\n");
if (IS_ERR(cl = class_create(THIS_MODULE, "char")))
{
cdev_del(&c_dev);
unregister_chrdev_region(dev, MINOR_CNT);
return PTR_ERR(cl);
}
printk("After class_create\n");
if (IS_ERR(dev_ret = device_create(cl, NULL, dev, NULL, "demo")))
{
class_destroy(cl);
cdev_del(&c_dev);
unregister_chrdev_region(dev, MINOR_CNT);
return PTR_ERR(dev_ret);
}
printk("After device_create\n");
return 0;
}
static void __exit query_ioctl_exit(void)
{
device_destroy(cl, dev);
class_destroy(cl);
cdev_del(&c_dev);
unregister_chrdev_region(dev, MINOR_CNT);
}
module_init(query_ioctl_init);
module_exit(query_ioctl_exit);
MODULE_LICENSE("GPL");
And after inserting the module I am able to see these messages:
$insmod demo_device.ko
Before calling alloc
After alloc 0 217055232
After cdev_add
After class_create
After device_create
$
Make sure that Major Number of the device is not preoccupied by some other device file. use the following command to check the occupied Major Numbers
cat /proc/devices
Use the following code to capture initialization error in init function
int t=register_chrdev(majorNumber,"mydev",&fops);
if(t<0)
printk(KERN_ALERT "device registration failed.");
Use dmesg to look into kernel logs
Look at module_flags_taint() in kernel/module.c.
The 'P' flag merely indicated the other modules are proprietary. The reason your device doesn't show up in /proc/devices is probably because something is wrong with the initialisation, but we can't help you with that unless you show us code.
After perfroming make clean to the linux/application source code and rebuilding it again...make it works. Now after inserting the module the corresponding entry is visibe in the /proc/devcies file :)
I expect to get numbers from 0 to 4 in random order, but instead, I have some unsynchronized mess
What i do wrong?
#include <iostream>
#include <windows.h>
#include <process.h>
using namespace std;
void addQuery(void *v );
HANDLE ghMutex;
int main()
{
HANDLE hs[5];
ghMutex = CreateMutex( NULL, FALSE, NULL);
for(int i=0; i<5; ++i)
{
hs[i] = (HANDLE)_beginthread(addQuery, 0, (void *)&i);
if (hs[i] == NULL)
{
printf("error\n"); return -1;
}
}
printf("WaitForMultipleObjects return: %d error: %d\n",
(DWORD)WaitForMultipleObjects(5, hs, TRUE, INFINITE), GetLastError());
return 0;
}
void addQuery(void *v )
{
int t = *((int*)v);
WaitForSingleObject(ghMutex, INFINITE);
cout << t << endl;
ReleaseMutex(ghMutex);
_endthread();
}
You have to read and write the shared variable inside the lock. You are reading it outside of the lock and thus rendering the lock irrelevant.
But even that's not enough since your shared variable is a loop variable that you are writing to without protection of the lock. A much better example would run like this:
#include <iostream>
#include <windows.h>
#include <process.h>
using namespace std;
void addQuery(void *v );
HANDLE ghMutex;
int counter = 0;
int main()
{
HANDLE hs[5];
ghMutex = CreateMutex( NULL, FALSE, NULL);
for(int i=0; i<5; ++i)
{
hs[i] = (HANDLE)_beginthread(addQuery, 0, NULL);
if (hs[i] == NULL)
{
printf("error\n"); return -1;
}
}
printf("WaitForMultipleObjects return: %d error: %d\n",
(DWORD)WaitForMultipleObjects(5, hs, TRUE, INFINITE), GetLastError());
return 0;
}
void addQuery(void *v)
{
WaitForSingleObject(ghMutex, INFINITE);
cout << counter << endl;
counter++;
ReleaseMutex(ghMutex);
_endthread();
}
If you can, use a critical section rather than a mutex because they are simpler to use and more efficient. But they have the same semantics in that they only protect code inside the locking block.
Note: Jerry has pointer out some other problems, but I've concentrated on the high level trheading and serialization concerns.
Your synchronization has some issues as you want to get numbers from 0 to 4 in random order.
The problem is that the variable i is write outside the lock and every time the addQuery method get called by the execution of a thread, it get the modified version of variable i. That why you may see 5 as the value at the output for all.
So, here is my fix for this scenario. Instead of pass the address of variable i in parameters of the function addQuery, you should pass it's value. Hope it helps:
#include <iostream>
#include <windows.h>
#include <process.h>
using namespace std;
void addQuery(void *v);
HANDLE ghMutex;
int main()
{
HANDLE hs[5];
ghMutex = CreateMutex(NULL, FALSE, NULL);
for (int i = 0; i<5; ++i)
{
hs[i] = (HANDLE)_beginthread(addQuery, 0, (void *)i);
if (hs[i] == NULL)
{
printf("error\n"); return -1;
}
}
printf("WaitForMultipleObjects return: %d error: %d\n",
(DWORD)WaitForMultipleObjects(5, hs, TRUE, INFINITE), GetLastError());
return 0;
}
void addQuery(void *v)
{
int t = (int)v;
WaitForSingleObject(ghMutex, INFINITE);
cout << t << endl;
ReleaseMutex(ghMutex);
_endthread();
}
How can I achieve the functionality given in ipconfig on Windows in VC++? I need to get local ip info of the machine, primary ip vs.
Well people, formerly I could not find something useful but I found the solution on this link.
// GetLocalIP.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <winsock2.h>
int _tmain(int argc, _TCHAR* argv[])
{
// Add 'ws2_32.lib' to your linker options
WSADATA WSAData;
// Initialize winsock dll
if(::WSAStartup(MAKEWORD(1, 0), &WSAData))
{
// Error handling
}
// Get local host name
char szHostName[128] = "";
if(::gethostname(szHostName, sizeof(szHostName)))
{
// Error handling -> call 'WSAGetLastError()'
}
// Get local IP addresses
struct sockaddr_in SocketAddress;
struct hostent *pHost = 0;
pHost = ::gethostbyname(szHostName);
if(!pHost)
{
// Error handling -> call 'WSAGetLastError()'
}
char aszIPAddresses[10][16]; // maximum of ten IP addresses
for(int iCnt = 0; ((pHost->h_addr_list[iCnt]) && (iCnt < 10)); ++iCnt)
{
memcpy(&SocketAddress.sin_addr, pHost->h_addr_list[iCnt], pHost->h_length);
strcpy(aszIPAddresses[iCnt], inet_ntoa(SocketAddress.sin_addr));
//std::cout << aszIPAddresses[iCnt] << endln;
}
// Cleanup
WSACleanup();
return 0;
}