Sample Header Ad - 728x90

ioctl SIOCGIWSTATS signal level constantly 0

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I have a block of C code that gets a variety of information about a network interface, namely the SSID and the signal level in dBm:
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define WIRELESS_INTERFACE "wlp2s0"

int main () {
      // Communicate using ioctl to get information
      struct iwreq wreq;
      int sockfd;
      char *ssid;

      // Allocate memory for the request
      memset(&wreq, 0, sizeof(struct iwreq));
      // Assign our interface name to the request
      sprintf(wreq.ifr_name, WIRELESS_INTERFACE);

      // Open socket for ioctl
      if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        fprintf(stderr, "FAILED 1");
        exit(1);
      }

      // Get SSID
      wreq.u.essid.pointer = ssid;
      wreq.u.essid.length = 32;
      if (ioctl(sockfd, SIOCGIWESSID, &wreq) == -1) {
        fprintf(stderr, "FAILED 2");
        exit(2);
      }

      fwrite(wreq.u.essid.pointer, 1, wreq.u.essid.length, stdout);

      struct iw_statistics *stats;
      int8_t signalLevel = 0;

      wreq.u.data.pointer = (struct iw_statistics *)malloc(sizeof(*stats));
      wreq.u.data.length = sizeof(*stats);
      wreq.u.data.flags = 1;
      if (ioctl(sockfd, SIOCGIWSTATS, &wreq) == -1) {
        fprintf(stderr, "FAILED 3");
        exit(3);
      }
      if (((struct iw_statistics *)wreq.u.data.pointer)->qual.updated &
          IW_QUAL_DBM) {
        fputs("\nSignal valid\n", stdout);
        // signal is measured in dBm and is valid for us to use
        signalLevel =
            ((struct iw_statistics *)wreq.u.data.pointer)->qual.level - 256;
      }
      fprintf(stdout, "\nsignalLevel %d\n", signalLevel);
}
Compiling and running with gcc stackoverflow.c -o stackoverflow && ./stackoverflow will always output the following:
Erebus
Signal valid

signalLevel 0
I have tried a new sockfd and wreq variable for each ioctl call but this does not work. I can confirm that other tools correctly report the signal level:
➜ nmcli -f IN-USE,SIGNAL,SSID device wifi

IN-USE  SIGNAL  SSID
        84      other1
        80      other2
        75      Erebus
        75      --
        75      other3
        75      Erebus
*       72      Erebus
        65      other3
        25      other5
        20      other6
However one tool confirmed to be using the same ioctl calls does not work, iwconfig wlp2s0 gives Signal level=0 dbm. Information about my system:
➜ uname -a
Linux jack-laptop 5.15.0-52-generic #58-Ubuntu SMP Thu Oct 13 08:03:55 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Ubuntu 22.04 Edit: I believe this is a driver specific issue so adding on information about the wireless driver:
02:00.0 Network controller: Qualcomm Atheros QCNFA765 (rev 01)
	Subsystem: Lenovo Device 9309
	Kernel driver in use: ath11k_pci
	Kernel modules: ath11k_pci
Asked by Jack828 (11 rep)
Nov 7, 2022, 09:46 PM
Last activity: Nov 8, 2022, 09:17 AM