While trying to call Acquire dbus api from our application , the bluez stack gets the fd, imtu, omtu successfully, and sends it over dbus using g_dbus_send_reply. But when we call dbus_connection_send_with_reply_and_block from our application, we are unable to get the reply,and unable to get the fd, imtu and omtu.The dbus is returning org.freedesktop.DBus.Error.NoReply.
dbus version used is 1.10.10.
Bluez version - 5.37
Dbus error seen is ,
method call time=1493814994.072004 sender=:1.50 -> destination=org.bluez serial=50 path=/org/bluez/hci0/dev_A4_70_D6_7A_74_7F/fd2; interface=org.bluez.MediaTransport1; member=Acquire
error time=1493814994.074396 sender=org.freedesktop.DBus -> destination=:1.50 error_name=org.freedesktop.DBus.Error.NoReply reply_serial=50
string "Message recipient disconnected from message bus without replying"
Bluetoothd error seen is,
State changed /org/bluez/hci0/dev_88_79_7E_84_2C_54/fd2: TRANSPORT_STATE_PENDING -> TRANSPORT_STATE_ACTIVE
bluetoothd[7523]: Disconnected from D-Bus. Exiting.
Any inputs will be of great help. Awaiting for the reply.
This issue is resolved by applying Smack patch for bluetooth.
This patch allows kernel sockets to be used by applications.
Patches are,
0001-Smack-File-receive-for-sockets.patch
0002-smack-fix-cache-of-access-labels.patch
0003-Smack-ignore-null-signal-in-smack_task_kill.patch
0004-Smack-Assign-smack_known_web-label-for-kernel-thread.patch
Gerrit link -
https://gerrit.automotivelinux.org/gerrit/#/c/6995/
Related
Using wpa_supplicant 2.4 on ARM Debian.
Is there a way to get signal level, in decibels or percents, of the wireless network I’m currently connected to?
STATUS command only returns the following set of values: bssid, freq, ssid, id, mode, pairwise_cipher, group_cipher, key_mgmt, wpa_state, ip_address, p2p_device_address, address, uuid
I can run SCAN afterwards, wait for results and search by SSID. But that’s slow and error-prone, I'd like to do better.
The driver should already know that information (because connected, and adjusting transmit levels for energy saving), is there a way to just query for that?
This question is not about general computing hardware and software. I'm using wpa_supplicant through a C API defined in wpa_ctrl.h header, interacting with the service through a pair of unix domain sockets (one for commands, another one for unsolicited events).
One reason I don’t like my current SCAN + SCAN_RESULT solution, it doesn’t work for hidden SSID networks. Scan doesn’t find the network, therefore I’m not getting signal level this way. Another issue is minor visual glitch at application startup. My app is launched by systemd, After=multi-user.target. Unless it’s the very first launch, Linux is already connected to Wi-Fi by then. In my app’s GUI (the product will feature a touch screen), I render a phone-like status bar, that includes WiFi signal strength icon. Currently, it initially shows minimal level (I know it's connected because STATUS command shows SSID), only after ~1 second I’m getting CTRL-EVENT-SCAN-RESULTS event from wpa_supplicant, run SCAN_RESULT command and update signal strength to the correct value.
On the API level my code is straightforward. I have two threads for that, both call wpa_ctrl_open, the command thread calls wpa_ctrl_request, the event thread has an endless loop that calls poll passing wpa_ctrl_get_fd() descriptor and POLLIN event mask, followed by wpa_ctrl_pending and wpa_ctrl_recv.
And here's the list of files in /sys/class/net/wlan0:
./mtu
./type
./phys_port_name
./netdev_group
./flags
./power/control
./power/async
./power/runtime_enabled
./power/runtime_active_kids
./power/runtime_active_time
./power/autosuspend_delay_ms
./power/runtime_status
./power/runtime_usage
./power/runtime_suspended_time
./speed
./dormant
./name_assign_type
./proto_down
./addr_assign_type
./phys_switch_id
./dev_id
./duplex
./gro_flush_timeout
./iflink
./phys_port_id
./addr_len
./address
./operstate
./carrier_changes
./broadcast
./queues/rx-0/rps_flow_cnt
./queues/rx-0/rps_cpus
./queues/rx-1/rps_flow_cnt
./queues/rx-1/rps_cpus
./queues/rx-2/rps_flow_cnt
./queues/rx-2/rps_cpus
./queues/rx-3/rps_flow_cnt
./queues/rx-3/rps_cpus
./queues/tx-0/xps_cpus
./queues/tx-0/tx_maxrate
./queues/tx-0/tx_timeout
./queues/tx-0/byte_queue_limits/limit
./queues/tx-0/byte_queue_limits/limit_max
./queues/tx-0/byte_queue_limits/limit_min
./queues/tx-0/byte_queue_limits/hold_time
./queues/tx-0/byte_queue_limits/inflight
./queues/tx-1/xps_cpus
./queues/tx-1/tx_maxrate
./queues/tx-1/tx_timeout
./queues/tx-1/byte_queue_limits/limit
./queues/tx-1/byte_queue_limits/limit_max
./queues/tx-1/byte_queue_limits/limit_min
./queues/tx-1/byte_queue_limits/hold_time
./queues/tx-1/byte_queue_limits/inflight
./queues/tx-2/xps_cpus
./queues/tx-2/tx_maxrate
./queues/tx-2/tx_timeout
./queues/tx-2/byte_queue_limits/limit
./queues/tx-2/byte_queue_limits/limit_max
./queues/tx-2/byte_queue_limits/limit_min
./queues/tx-2/byte_queue_limits/hold_time
./queues/tx-2/byte_queue_limits/inflight
./queues/tx-3/xps_cpus
./queues/tx-3/tx_maxrate
./queues/tx-3/tx_timeout
./queues/tx-3/byte_queue_limits/limit
./queues/tx-3/byte_queue_limits/limit_max
./queues/tx-3/byte_queue_limits/limit_min
./queues/tx-3/byte_queue_limits/hold_time
./queues/tx-3/byte_queue_limits/inflight
./tx_queue_len
./uevent
./statistics/rx_fifo_errors
./statistics/collisions
./statistics/rx_errors
./statistics/rx_compressed
./statistics/rx_dropped
./statistics/tx_packets
./statistics/tx_errors
./statistics/rx_missed_errors
./statistics/rx_over_errors
./statistics/tx_carrier_errors
./statistics/tx_heartbeat_errors
./statistics/rx_crc_errors
./statistics/multicast
./statistics/tx_fifo_errors
./statistics/tx_aborted_errors
./statistics/rx_bytes
./statistics/tx_compressed
./statistics/tx_dropped
./statistics/rx_packets
./statistics/tx_bytes
./statistics/tx_window_errors
./statistics/rx_frame_errors
./statistics/rx_length_errors
./dev_port
./ifalias
./ifindex
./link_mode
./carrier
You can get the signal level of the connected wifi by wpa_supplicant cmd SIGNAL_POLL
The wpa_supplicant would return:
RSSI=-60
LINKSPEED=867
NOISE=9999
FREQUENCY=5745
The value of the RSSI is the signal level.
You can get the signal level of the connected wifi by wpa_supplicant cmd BSS <bssid>.
About the bssid of the connected wifi, you can get from wpa_supplicant cmd STATUS.
https://android.googlesource.com/platform/external/wpa_supplicant_8/+/622b66d6efd0cccfeb8623184fadf2f76e7e8206/wpa_supplicant/ctrl_iface.c#1986
For iw compatible devices:
Following command gives the current station(aka AP) signal strength:
iw dev wlp2s0 station dump -v
If you need C API, just dig the source code of iw.
After a quick glance, the function you need is here
For broadcom devices, try search broadcom wl. It is close source, don't know if C API is provided.
I will give a detailed exp of the program and lead to the issue regarding the use of netlink socket communication.
The last paragraph asks the actual question I need an answer for, so you might wanna start by peeking it first.
Disclaimer before I start:
- I have made an earlier search before asking here and did not find complete solution / alternative to my issue.
- I know how to initialize a module and insert it to kernel.
- I know to handle communication between module and user-space without using netlink sockets. Meaning using struct file_operations func pointers assignments to later be invoked by the module program whenever a user attempts to read/write etc. and answer to the user using copy_to_user / copy_from_user.
- This topic refers to Linux OS, Mint 17 dist.
- Language is C
Okay, so I am building a system with 3 components:
1. user.c : user application (user types commands here)
2. storage.c : storage device ('virtual' disk-on-key)
3. device.ko : kernel module (used as proxy between 1. and 2.)
The purpose of this system is to be able (as a user) to:
- Copy files to the virtual disk-on-key device (2) - like an "upload" from local directory that belongs to the user.
- Save files from the virtual device on local directory - like "download" from the device storage to the user directory.
Design:
Assuming programs (1),(2) are compiled and running + (3) has successfully inserted using the bash command ' sudo insmod device.ko ' , the following should work like this (simulation ofc):
Step 1 (in user.c) -> user types 'download file.txt'
Step 2 (in device.ko) -> the device recognizes the user have tried to 'write' to it (actually user just passing the string "download file.txt") and invokes the 'write' implementation of the method we set on struct file_operation earlier on module_init().
The device (kernel module) now passes the data (string with a command) to the storage.c application, expecting an answer to later be retrieved to the user.c application.
Step 3 (in storage.c) -> now, lets say this program performs a busy-wait loop of 'readmsg()' and that's how a request from module event is triggered and recognized, the storage device now recognizes that the module has sent a request (string with a command \ data). Now, the storage programs shall perform an implementation of some function 'X' to send the data requested using sendmsg() somewhere inside the function.
Now, here comes the issue.
Usually, on all of the examples I've looked on web, the communication between the kernel-module and a user-space (or the storage.c program in our case) using netlink is triggered by the user-space and not vice versa. Meaning that the sendmsg() function from the user-space invokes the 'request(struct sk_buff *skb)' method (which is set on the module_init() part as following:
struct netlink_kernel_cfg cfg = {
.input = request // when storage.c sends something, it invokes the request function
};
so when the storage.c performs something like:
sendmsg(sock_fd,&msg,0); // send a msg to the module
the module invokes and runs the:
static void request(struct sk_buff *skb) {
char *msg ="Hello from kernel";
msg_size=strlen(msg);
netlink_holder=(struct nlmsghdr*)skb->data;
printk(KERN_INFO "Netlink received msg payload:%s\n",(char*)nlmsg_data(netlink_holder));
pid = netlink_holder->nlmsg_pid; // pid of sending process
skb_out = nlmsg_new(msg_size,0);
if(!skb_out){
printk(KERN_ERR "Failed to allocate new skb\n");
return;
}
netlink_holder=nlmsg_put(skb_out,0,0,NLMSG_DONE,msg_size,0); // add a new netlink message to an skb. more info: http://elixir.free-electrons.com/linux/v3.2/source/include/net/netlink.h#L491
NETLINK_CB(skb_out).dst_group = 0; // not in multicast group
strncpy(nlmsg_data(netlink_holder),msg,msg_size); // assign data as char* (variable msg)
result=nlmsg_unicast(sock_netlink,skb_out,pid); // send data to storage. more info: http://elixir.free-electrons.com/linux/latest/source/include/net/netlink.h#L598
if(result<0)
printk(KERN_INFO "Error while sending bak to user\n");
}
and from all that big chunk, the only thing that im interesting in is actually doing this:
result=nlmsg_unicast(sock_netlink,skb_out,pid); // send data to storage.
BUT I can't use nlmsg_unicast() without having the strcut sk_buff* which is provided automatically for me whenever there's an invoke from storage.c !
To sum up everything:
How do I send a msg from the device.ko (kernel module) to the user-space withtout having to wait for request to invoke / rely on the provided strcut sk_buff parameter from the earlier shown 'request()' method ?
Hope this sums up the point.
Thanks.
The only question here is that you need the user-space program connected to kernel-space first to get the pid of your user-program.
After get the pid, you can manually construct the skb_out and send it out through netlink_unicast or nlmsg_unicast.
The pid is always needed, you can set it as static and let your user-space program connect to your device.ko to make a long-maintained link.
Although this question is asked at 2017, I believe OP has already found the answer :D
We have a C program (a client that connects to our server). The program uses Win32 API:s to create controls etc. It is a single-threaded application. Lately the application has started to hang at random in Windows 7.
Thanks to Application Verifier, I could detect problematic APIs and rectified them.
Now there are still some customers reporting a "non-responsive" situation.
A crash dump from their side reveals the following API:
SendMessage(HWND_BROADCAST, WM_DDE_INITIATE, (WPARAM)hClient, MAKELONG(aAppl,aTopic));
Yes its sending a DDE command to WinWord.exe. Task Manager shows Winword in non-responsive state.
Evtx reveals the following:
Fault bucket , type 0
Event Name: AppHangXProcB1
Response: Not available
Cab Id: 0
Problem signature:
P1: OurApplication.exe
P2: 14.14.1.50
P3: 537337f4
P4: b6f1
P5: 32
P6: WINWORD.EXE
P7: 15.0.4615.1000
P8:
P9:
P10:
Attached files:
C:\Users\diane-do\AppData\Local\Temp\WER91C7.tmp.appcompat.txt
C:\Users\diane-do\AppData\Local\Temp\WER958F.tmp.WERInternalMetadata.xml
C:\Users\diane-do\AppData\Local\Temp\WER968B.tmp.xml
C:\Users\diane-do\AppData\Local\Temp\WER969C.tmp.hdmp
C:\Users\diane-do\AppData\Local\Temp\WER9777.tmp.mdmp
These files may be available here:
C:\Users\diane-do\AppData\Local\Microsoft\Windows\WER\ReportQueue\AppHang_OurApplication.exe_e9b582fc22d416b8787c1184f6fe7fa19d63_cab_0fde97a1
Analysis symbol:
Rechecking for solution: 0
Report Id: 9e84daa9-eff8-11e3-a2fb-90b11c841d1a
Report Status: 36
Any help would be appreciated.
Please note the above is Win 7 64-bit, while our application is 32 bit. Don't know what build their Office 2013 is (32 or 64 bit)
I am aware of the following:
- DDE is old technology, but changing it is out of question now.
- For the above case, I cant use SendMessageTimeout APIs as our client has to wait until commands complete.
ONCE AGAIN, The hang (non-responsive state) happens at random, not always at DDE but various instances. While computing something, even while doing a simple operation as below. Customers launch our CHM file from our menu, then Alt+Tab to another application and then Alt+Tab back to our application, our application becomes non-responsive.
P.S: I also didn't find any document online as to how to interpret those evtx application logs , what P1 P2 stand for. What signatures meant or what fault bucket type are, or any meaning of AppHangXProcB1 or AppHangB1 etc. Please pass the link if you have for the same.
sendmessage is a blocking call it will return only after the receiver application processes the message. Here, it got blocked & it as well blocked your application from dispatching the message. Since your application can't process any further window messages, it hanged the GUI.
Check again all the processing done on processing a window message for any blocking calls like waitforsingleobject, recv, connect in it.
I thought I would try out SDP on our infiniband hardware.
However, when I try to add AF_INET_SDP as the first argument to socket() I get the following error:
"Address family not supported by protocol".
Originally I had:
#define AF_INET_SDP 26
But after doing some reading, noticed a patch applied some time back to change this value to 27.
When set to 26 I get the error:
"Error binding socket: No such device"
Has anyone managed to get SDP working on Ubuntu 12.04? what did you do to get it up and running?
I have installed libsdp1 and libsdpa-dev
Using the LD_PRELOAD method on iperf I also get the first error:
LD_PRELOAD=libsdp.so iperf -s
dir: /tmp/libsdp.log.1000 file: /tmp/libsdp.log.1000/log
socket failed: Address family not supported by protocol
bind failed: Bad file descriptor
Therefore I assume 27 is the correct domain number.
SDP hasn't been accepted on the mainline linux kernel. On recent fedora, they don't ship it, neither the user space libsdp.
If you still want to experiment, Matt is right, the module in question is 'ib_sdp'.
try modprobe ib_sdp and run your example again.
My app uses libssh2 to communicate over SSH, and generally works fine. One problem I have is when the remote host dies unexpectedly -- the remote host in this case is an embedded device that can lose power at any time, so this isn't uncommon.
When that happens, my app detects that the remote computer has stopped responding to pings, and tears down the local end of the SSH connection like this:
void SSHSession :: CleanupSession()
{
if (_uploadFileChannel)
{
libssh2_channel_free(_uploadFileChannel);
_uploadFileChannel = NULL;
}
if (_sendCommandsChannel)
{
libssh2_channel_free(_sendCommandsChannel);
_sendCommandsChannel = NULL;
}
if (_session)
{
libssh2_session_disconnect(_session, "bye bye");
libssh2_session_free(_session);
_session = NULL;
}
}
Pretty straightforward, but the problem is that the libssh2_channel_free() calls can block for a long time waiting for the remote end to respond to the "I'm going away now" message, which it will never do because it's powered off... but in the meantime, my app is frozen (blocked in the cleanup-routine), which isn't good.
Is there any way (short of hacking libssh2) to avoid this? I'd like to just tear down the local SSH data structures, and never block during this tear-down. (I suppose I could simply leak the SSH session memory, or delegate it to a different thread, but those seem like ugly hacks rather than proper solutions)
I'm not experienced with libssh2, but perhaps we can get different behavior out of libssh2 by using libssh2_session_disconnect_ex and a different disconnect reason: SSH_DISCONNECT_CONNECTION_LOST.
libssh2_session_disconnect is equivalent to using libssh2_session_disconnect_ex with the reason SSH_DISCONNECT_BY_APPLICATION. If libssh2 knows that the connection is lost, maybe it won't try to talk to the other side.
http://libssh2.sourceforge.net/doc/#libssh2sessiondisconnectex
http://libssh2.sourceforge.net/doc/#sshdisconnectcodes
Set to non-blocking mode and take the control of reading data from the socket to your hand by setting callback function to read data from the soket using libssh2_session_callback_set with LIBSSH2_CALLBACK_RECV for cbtype
void *libssh2_session_callback_set(LIBSSH2_SESSION *session, int cbtype, void *callback);
If you can't read data from the socket due to error ENOTCONN that means remote end has closed the socket or connection failed, then return -ENOTCONN in your callback function