Getting local bluetooth address - c++

I am trying to get the Bluetooth address of the local device using the Microsoft Bluetooth stack. I am targetting a Windows CE 6.0 device.
On MSDN I found the following code example :
SOCKADDR_BTH sab;
int len = sizeof(sab);
if (0 == getsockname (s, &sab, &len)) {
wprintf (L"Local Bluetooth device is %04x%08x, server channel = %d\n",
GET_NAP(sab.btAddr), GET_SAP(sab.btAddr), sab.port);
}
At : https://msdn.microsoft.com/en-us/library/ee495768(v=winembedded.60).aspx
In this example, s is not declared, so I assume its just a valid socket...
Here is the code I've written based on this example :
SOCKET s = socket( AF_BTH, SOCK_STREAM, BTHPROTO_RFCOMM );
if( s == INVALID_SOCKET )
{
return false;
}
SOCKADDR_BTH sab;
int len = sizeof( sab );
if( 0 == getsockname(s, (sockaddr *) & sab, & len ) )
{
// Use the BT address here
closesocket( s );
return true;
}
else
{
closesocket( s );
return false;
}
I had to cast the SOCKADDR_BTH * to a sockaddr * since the compiler wouldn't let me compile this, unlike what the example lets think.
This is getting me a 10022 error code indicating that I'm providing an invalid argument, which is not really surprising me due to this weird cast I had to do.
I Also tried another method involving the function BthReadLocalAddr which is documented on MSDN at : https://msdn.microsoft.com/en-us/library/ms887876.aspx
The function is indeed declared in Bt_api.h, but there is no Btdrt.lib in the CE 6.0 SDK. However there is a Btd.lib, but it doesn't seem to contain the definition of that function since I'm getting an unresolved external link error, which is not surprising.
How can I get this to work ? And maybe find a valid documentation about the MS bluetooth API that doesn't refer to files that do not exist ? Thank you.

Related

poll() method not working in Linux but working in Mac

I am using C++ code snippet for port forwarding. The requirement is to do the hand shake between two ports. It should be two way communication. That is to forward what ever iscoming on the source port to destination port. And then to forward the response of the destination port to the source port.
This piece of code is working as expected on my mac system. But when I am running this code on Linux system I am facing one issue.
Issue:
The C++ code that I am using is having 3 parts:
establish_connection_to_source();
open_connection_to_destination();
processconnetion();
On Linux: establish_connection_to_source(); and open_connection_to_destination(); is working perfectly fine. But processconnetion(); is havng one issue.
Following is the process connection method:
void processconnetion()
{
buffer *todest = new buffer(socket_list[e_source].fd,socket_list[e_dest].fd);
buffer *tosrc = new buffer(socket_list[e_dest].fd,socket_list[e_source].fd);
if (todest == NULL || tosrc == NULL){
fprintf(stderr,"out of mememory\n");
exit(-1);
}
unsigned int loopcnt;
profilecommuncation srcprofile(COMM_BUFSIZE);
profilecommuncation destprofile(COMM_BUFSIZE);
while (true) {
int withevent = poll(socket_list, 2, -1);
loopcnt++;
fprintf(stderr,"loopcnt %d socketswith events = %d source:0x%x dest:0x%x\n", loopcnt, withevent, socket_list[e_source].revents, socket_list[e_dest].revents);
if ((socket_list[e_source].revents | socket_list[e_dest].revents) & (POLLHUP | POLLERR)) {
// one of the connections has a problem or has Hungup
fprintf(stderr,"socket_list[e_source].revents= 0x%X\n", socket_list[e_source].revents);
fprintf(stderr,"socket_list[e_dest].revents= 0x%X\n", socket_list[e_dest].revents);
fprintf(stderr,"POLLHUP= 0x%X\n", POLLHUP);
fprintf(stderr,"POLLERR= 0x%X\n", POLLERR);
int result;
socklen_t result_len = sizeof(result);
getsockopt(socket_list[e_dest].fd, SOL_SOCKET, SO_ERROR, &result, &result_len);
fprintf(stderr, "result = %d\n", result);
fprintf(stderr,"exiting as one connection had an issue\n");
break;
}
if (socket_list[e_source].revents & POLLIN) {
srcprofile.increment_size(todest->copydata());
}
if (socket_list[e_dest].revents & POLLIN) {
destprofile.increment_size(tosrc->copydata());
}
}
delete todest;
delete tosrc;
close(socket_list[e_source].fd);
close(socket_list[e_dest].fd);
srcprofile.dumpseensizes("source");
destprofile.dumpseensizes("destination");
}
Here it is giving error - exiting as one connection had an issue that means that if ((socket_list[e_source].revents | socket_list[e_dest].revents) & (POLLHUP | POLLERR)) is returning true. The issue is with the destination port and not in case of source.
Note:
Variales used in the processconnetion(); method:
socket_list is a structure of type pollfd. Following is the description:
struct pollfd {
int fd;
short events;
short revents;
};
pollfd socket_list[3];
#define e_source 0
#define e_dest 1
#define e_listen 2
Following is the output at the time for exit:
connecting to destination: destination IP / 32001.
connected...
loopcnt 1 socketswith events = 1 source:0x0 dest:0x10
socket_list[e_source].revents= 0x0
socket_list[e_dest].revents= 0x10
POLLHUP= 0x10
POLLERR= 0x8
result = 0
exiting as one connection had an issue
int withevent = poll(socket_list, 2, -1); here the withevent value returned is 1
Socket List Initialisation:
guard( (socket_list[e_listen].fd = socket( PF_INET, SOCK_STREAM, IPPROTO_TCP )), "Failed to create socket listen, error: %s\n", "created listen socket");
void guard(int n, char *msg, char *success)
{
if (n < 0) {
fprintf(stderr, msg, strerror(errno) );
exit(-1);
}
fprintf(stderr,"n = %d %s\n",n, success);
}
I am not able to figure out the issue as it is working fine in mac. Any leads why this behaviour in Linux is highly appreciated. Thanks in advance.

Check if lan device is connected using c++ in linux

I have a device on my network (wi-fi with only static IP's) with a static IP address of 192.168.1.17. I use it in input for part of my code in a c++ program in linux, but if it disconnects/is powered off, the program stops responding because it tries to pull data from a non-existent location. Is there a way I can check if it disconnects so that I can stop the program before it goes out of control? Thanks for the helpful responses I know are coming!
Use ioctl SIOCGIFFLAGS to check is the interface UP and RUNNING:
struct ifreq ifr;
memset( &ifr, 0, sizeof(ifr) );
strcpy( ifr.ifr_name, ifrname );
if( ioctl( dummy_fd, SIOCGIFFLAGS, &ifr ) != -1 )
{
up_and_running = (ifr.ifr_flags & ( IFF_UP | IFF_RUNNING )) == ( IFF_UP | IFF_RUNNING );
}
else
{
// error
}
Input variable is ifrname. It should be the interface name "eth0", eth1", "ppp0" ....
Because ioctl() needs a file descriptor as parameter, you can use for example some temporary UDP socket for that:
dummy_fd = socket( AF_INET, SOCK_DGRAM, 0 );
Remember to close the socket, when not used anymore.
See how to go very low-level and use ioctl(7). See lsif by Adam Risi for an example.
Try to ping 192.168.1.17 before proceeding
int status = system("ping -c 2 192.168.1.17");
if (-1 != status)
{
ping_ret = WEXITSTATUS(status);
if(ping_ret==0)
cout<<"Ping successful"<<endl; ////Proceed
else
cout<<"Ping not successful"<<endl; ///Sleep and agin check for ping
}

ZeroMQ: Address in use error when re-binding socket

After binding a ZeroMQ socket to an endpoint and closing the socket, binding another socket to the same endpoint requires several attempts. The previous calls to zmq_bind up until the successful one fail with the error "Address in use" (EADDRINUSE).
The following code demonstrates the problem:
#include <cassert>
#include <iostream>
#include "zmq.h"
int main() {
void *ctx = zmq_ctx_new();
assert( ctx );
void *skt;
skt = zmq_socket( ctx, ZMQ_REP );
assert( skt );
assert( zmq_bind( skt, "tcp://*:5555" ) == 0 );
assert( zmq_close( skt ) == 0 );
skt = zmq_socket( ctx, ZMQ_REP );
assert( skt );
int fail = 0;
while ( zmq_bind( skt, "tcp://*:5555" ) ) { ++fail; }
std::cout << fail << std::endl;
}
I'm using ZeroMQ 4.0.3 on Windows XP SP3, compiler is VS 2008. libzmq.dll has been built with the provided Visual Studio solution.
This prints 1 here when doing a "Debug" build (both of the code above and of libzmq.dll) and 0 using a "Release" build. Strange enough, when running the code above with mixed build configuration (Debug with Release lib), fail counts up to 6.
Pieter Hintjens gave me the hint on the mailing list:
The call to zmq_close initiates the socket shutdown. This is done in a special "reaper" thread started by ZeroMQ to make the call to zmq_close asynchronous and non-blocking. See "The reaper thread" in a whitepaper about ZeroMQ's architecture.
The code above does not wait for the thread doing the actual work, so the endpoint will not become available immediately.
When a TCP socket is closed, it enters a state called TIME_WAIT. This means that while the socket is in that state, it's not really closed, and that in turn means that the address used by the socket is not available until it leave the state.
So if you run your program two times in close succession the socket will be in this TIME_WAIT state from the first run when you try the second run, and you get an error like this.
You might want to read more about TCP, and especially about its operation and states.

Segfault on FD_ISSET

I've run into a rather strange problem:
I use select() in order to determine if a socket becomes readable. However, whenever a client connects, I get a segfault when I call FD_ISSET() to check if a given socket is present in the fd_set.
/* [...] */
while( /* condition */ ){
timeout.tv_sec = 0;
timeout.tv_usec = SELECT_TIMEOUT;
//this simply fills sockets with some file descriptors (passed in by clients - both parameters are passed by reference)
maxfd = this->build_fd_set( clients, sockets );
//wait until something relevant happens
readableCount = select( maxfd + 1, &sockets, (fd_set*)NULL, (fd_set*)NULL, &timeout );
if( readableCount > 0 ){
//Some sockets have become readable
printf( "\nreadable: %d, sockfd: %d, maxfd: %d\n",
readableCount, this->sockfd, maxfd );
//Check if listening socket has pending connections
// SEGFAULT OCCURS HERE
if( FD_ISSET( this->sockfd, &sockets ) ) {
DBG printf( "new connection incoming" );
this->handle_new_connection( clients );
/* [...] */
}else {
// Data is pending on some socket
/* [...] */
}
}else if( readableCount < 0 ) {
//An error occured
/* [...] */
return;
}else {
// select has timed out
/* [...] */
}
}
EDIT:
Yeah, sorry for the sparse info: I've updated the code.
this->sock_fd is set up to be a descriptor for a listening socket, created usingthis->sockfd = socket( AF_UNIX, SOCK_STREAM, 0 ); and then made listening via listen( this->sockfd, ACCEPT_BACKLOG ).
build_fd_set:
int SvcServer::build_fd_set( const vector<int>& clients, fd_set& sockets ) {
//build up the socket set
FD_ZERO( &sockets );
FD_SET( this->sockfd, &sockets ); //listening socket is always part of the set
int maxfd = this->sockfd;
//Add all currently connected sockets to the list
for( vector<int>::const_iterator it = clients.begin() ; it != clients.end() ; ++it ) {
FD_SET( *it, &sockets );
maxfd = max( maxfd, *it );
}
return maxfd;
}
It really doesn't matter what clients is, it' just empty and meant to be filled once clients connect, which is not happening since the whole thing segfaults on the first incoming connection.
Also, here's some sample output:
readable: 1, sockfd: 3, maxfd: 3
Segmentation fault
The things I can derive here are:
The call to select() works, readable is set correctly
Also sockfd and maxfd are valid descriptors.
I'm afraid I can't provide you with any debugging info (e.g. gdb) since I'm cross compiling and gdb is not available on the platform I'm compiling to.
Nevermind, I figured it out. * stupid me *
Turns out, the segfault was never actually occuring at the suspected position, the last printf before the segfault never got shown because it stdout wasn't flushed. The actual segfault occured a little later and was (of course) my mistake.
thx nevertheless

Crash when connecting to Bluetooth device via WinAPI Socket (Access violation reading location 0x00000004)

I think you are my last hope. I have got here a Bluetooth device (it is a sensor to be more precisely) which I want to connect to and read data from. The device offers SPP (Serial Port Profile). To avoid the problem of reliable mapping from Bluetooth addresses and virtual serial ports (COM Ports), I am going to use sockets.
Unfortunately the application always crashes before returning from WinAPI function connect(...) with: 0xC0000005: Access violation reading location 0x00000004, so I get no error code.
BUT, and that is weird, when I right-click on the Bluetooth System Tray Icon to to show available devices, my device shows up being authenticated and connected. This list was empty before, of course.
My OS is Windows 7 64 Bit, the IDE is Visual Studio 2010, Microsoft Bluetooth Stack. Code to find and connect to my only device:
#include <iostream>
#include <string>
#include <algorithm>
#include <cassert>
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <BluetoothAPIs.h>
#include <Winsock2.h>
#include <Ws2bth.h>
BOOL auth_callback_ex(LPVOID pvParam, PBLUETOOTH_AUTHENTICATION_CALLBACK_PARAMS authParams)
{
BLUETOOTH_AUTHENTICATE_RESPONSE response;
response.bthAddressRemote = authParams->deviceInfo.Address;
response.authMethod = authParams->authenticationMethod; // == BLUETOOTH_AUTHENTICATION_METHOD_LEGACY
UCHAR pin[] = "1234";
std::copy(pin, pin+sizeof(pin), response.pinInfo.pin);
response.pinInfo.pinLength = sizeof(pin)-1; //excluding '\0'
response.negativeResponse = false;
HRESULT err = BluetoothSendAuthenticationResponseEx(NULL, &response);
if (err)
{
std::cout << "BluetoothSendAuthenticationResponseEx error = " << err << std::endl;
}
return true;
}
int main()
{
BLUETOOTH_DEVICE_SEARCH_PARAMS btSearchParams;
btSearchParams.dwSize = sizeof(BLUETOOTH_DEVICE_SEARCH_PARAMS);
btSearchParams.cTimeoutMultiplier = 5; //5*1.28s search timeout
btSearchParams.fIssueInquiry = true; //new inquiry
//return all known and unknown devices
btSearchParams.fReturnAuthenticated = true;
btSearchParams.fReturnConnected = true;
btSearchParams.fReturnRemembered = true;
btSearchParams.fReturnUnknown = true;
btSearchParams.hRadio = NULL; //search on all local radios
BLUETOOTH_DEVICE_INFO btDeviceInfo;
ZeroMemory(&btDeviceInfo, sizeof(BLUETOOTH_DEVICE_INFO)); //"initialize"
btDeviceInfo.dwSize = sizeof(BLUETOOTH_DEVICE_INFO);
HBLUETOOTH_DEVICE_FIND btDeviceFindHandle = NULL;
btDeviceFindHandle = BluetoothFindFirstDevice(&btSearchParams, &btDeviceInfo);
if(btDeviceFindHandle)
{
HBLUETOOTH_AUTHENTICATION_REGISTRATION authCallbackHandle = NULL;
DWORD err = BluetoothRegisterForAuthenticationEx(&btDeviceInfo, &authCallbackHandle, &auth_callback_ex, NULL);
if (err != ERROR_SUCCESS)
{
DWORD err = GetLastError();
std::cout << "BluetoothRegisterForAuthentication Error" << err << std::endl;
}
/////////////// Socket
WSADATA wsaData;
err = WSAStartup(MAKEWORD(2,2), &wsaData);
if (err)
{
std::cout << "WSAStartup error = " << err << std::endl;
}
// create BT socket
SOCKET s = socket (AF_BTH, SOCK_STREAM, BTHPROTO_RFCOMM);
assert(s != INVALID_SOCKET); //WSAGetLastError //throw // runtime check release?
SOCKADDR_BTH btSockAddr;
btSockAddr.addressFamily = AF_BTH;
btSockAddr.btAddr = btDeviceInfo.Address.ullLong;
btSockAddr.serviceClassId = RFCOMM_PROTOCOL_UUID; //SerialPortServiceClass_UUID (no difference)
btSockAddr.port = BT_PORT_ANY;
err = connect(s, reinterpret_cast<SOCKADDR*>(&btSockAddr), sizeof(SOCKADDR_BTH));
/* <--- never got so far --> */
if (err)
{
DWORD wsaErr = WSAGetLastError();
std::cout << "connect error = " << wsaErr << std::endl;
}
else
{
//err = shutdown(s, SD_BOTH);
err = closesocket(s);
if (err)
{
std::cout << "closesocket error = " << err << std::endl;
}
}
WSACleanup();
///////////////Socket
BOOL ok = BluetoothUnregisterAuthentication(authCallbackHandle);
if (!ok)
{
DWORD err = GetLastError();
std::cout << "BluetoothUnregisterAuthentication Error" << err << std::endl;
}
ok = BluetoothFindDeviceClose(btDeviceFindHandle);
if (!ok)
{
DWORD err = GetLastError();
std::cout << "BluetoothDeviceClose Error" << err << std::endl;
}
}
else
{
DWORD err = GetLastError();
std::cout << "BluetoothFindFirstDevice Error" << err << std::endl;
}
std::cin.get();
}
I have made some few more observations:
The authentication callback and the BluetoothSendAuthenticationResponseEx function are working fine, there is no error given back.
If I do not install the authentication callback (BluetoothRegisterForAuthenticationEx) and therefore have to manually enter the PIN (the UI shows up automatically while trying to connect), connect function returns properly and everything works fine, too. I even got data (the recv part is omitted in this snippet).
If I search and pair completely manually (Bluetooth Tray Icon -> Add Device), everything is fine, too. A service and a virtual serial port is installed. Data come via putty.
So somewhere between calling the authentication callback and end of the connect function something is going wrong. Maybe when trying to get a certain structure data via a pointer, which should not be NULL, plus offset.
Or am I doing something wrong? Is there something missing?
Thanks...
The problem is that your function is using the wrong calling convention. According to MSDN, you need to use the CALLBACK macro, as in:
BOOL CALLBACK auth_callback_ex(LPVOID pvParam, PBLUETOOTH_AUTHENTICATION_CALLBACK_PARAMS authParams)
Having the wrong calling convention will result in a stack mismatch on return, which could cause an access violation inside the MS Bluetooth code when it can't find its local variables.
Or it could result in the parameters to your function being all jumbled. If authParams and pvParam are swapped, because the cdecl calling convention expects args pushed from right to left and stdcall pushes them left to right, you'd get NULL in authParams, and then authParams->deviceInfo.Address will try to read address 0x04.
The compiler should have caught this. Compile with maximum warnings turned on (/W4). You'll have to ignore the warnings about unknown pragma, this is a bug in the header which I'm reporting to Microsoft (misspelled #pragma deprecated).
Unfortunately there's a second bug in the header, much more serious, of not specifying the calling convention explicitly, with the result that it will only work correctly on x86 (32-bit code) if /Gz is used. Yuck!
Followup: In the SDK headers shipped with VS2013, both issues are fixed.
You have a null-pointer access somewhere. "Access violation reading location 0x00000004" indicates that, as it is only 4 bytes away from zero.
I have a couple of thoughts to share with you, but be advised that these are hunches. I haven't compiled and debugged your code, although I commend you for posting a complete sample.
I think the crash may be within your authentication callback function, due to a '''NULL''' pointer dereference.
These lines:
response.bthAddressRemote = authParams->deviceInfo.Address;
response.authMethod = authParams->authenticationMethod; // == BLUETOOTH_AUTHENTICATION_METHOD_LEGACY
will cause the message you describe, if you are running on 32-bit Windows, and '''authParams''' may be '''NULL''' -- in that case, '''deviceInfo''' contributes a zero offset (it is at the beginning of the '''BLUETOOTH_AUTHENTICATION_CALLBACK_PARAMS'''), and '''.Address''' does contribute an offset of 4 ('''NULL + 4 == 0x00000004'''), because it follows a '''DWORD''' and nothing else within the '''BLUETOOTH_DEVICE_INFO''' layout.
Is it possible that '''authParams''' is NULL when your callback is called?
As another poster has already mentioned, this could be due to incorrect calling convention (lack of '''CALLBACK''' macro) -- causing otherwise correct parameters to mis-align with the positions the compiled code is reading.
The second thought was:
BLUETOOTH_DEVICE_INFO btDeviceInfo;
ZeroMemory(&btDeviceInfo, sizeof(BLUETOOTH_DEVICE_INFO)); //"initialize"
btDeviceInfo.dwSize = sizeof(BLUETOOTH_DEVICE_INFO);
Can be represented by:
BLUETOOTH_DEVICE_INFO btDeviceInfo = {sizeof(BLUETOOTH_DEVICE_INFO)};
According to the standard, this will zero the other fields of '''btDeviceInfo'''.
Or write managed code and use my Bluetooth library 32feet.NET Super simple. http://32feet.codeplex.com/
Will it crash then -- if so there's something wrong on your PC...