C example code to list all network interfaces and check whether they are wireless or not. Linux only. Tested on Ubuntu 10.04 and 12.04, but should be compatible with pretty much everything out there.

is_wireless.c

#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/wireless.h>


int check_wireless(const char* ifname, char* protocol) {
  int sock = -1;
  struct iwreq pwrq;
  memset(&pwrq, 0, sizeof(pwrq));
  strncpy(pwrq.ifr_name, ifname, IFNAMSIZ);

  if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("socket");
    return 0;
  }

  if (ioctl(sock, SIOCGIWNAME, &pwrq) != -1) {
    if (protocol) strncpy(protocol, pwrq.u.name, IFNAMSIZ);
    close(sock);
    return 1;
  }

  close(sock);
  return 0;
}


int main(int argc, char const *argv[]) {
  struct ifaddrs *ifaddr, *ifa;

  if (getifaddrs(&ifaddr) == -1) {
    perror("getifaddrs");
    return -1;
  }

  /* Walk through linked list, maintaining head pointer so we
     can free list later */
  for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
    char protocol[IFNAMSIZ]  = {0};

    if (ifa->ifa_addr == NULL ||
        ifa->ifa_addr->sa_family != AF_PACKET) continue;

    if (check_wireless(ifa->ifa_name, protocol)) {
      printf("interface %s is wireless: %s\n", ifa->ifa_name, protocol);
    } else {
      printf("interface %s is not wireless\n", ifa->ifa_name);
    }
  }

  freeifaddrs(ifaddr);
  return 0;
}

Hey, just a quick question, why does every call require a fresh socket? Is there a way to reuse them by instantiating the socket in the main function and passing it as a pointer to is_wireless? That would be cool and save several calls to open a socket.

Ha nm, I figured it out I'm a dumbass.

We have to go back to machine language so that we can do something more efficient and credible because I don't trust the available c libraries.