linux wifi 应用编程

sudo iwlist wlan0 scan

iwconfig wlan0 txpower 20

#include <net/if.h>
#include <sys/ioctl.h>
#include <stdio.h>

int main() {
    int sockfd;
    struct ifreq ifr;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    strncpy(ifr.ifr_name, "wlan0", IFNAMSIZ-1);
    ioctl(sockfd, SIOCGIFFLAGS, &ifr);

    if (ifr.ifr_flags & IFF_UP)
        printf("Interface is up\n");
    else
        printf("Interface is down\n");

    close(sockfd);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/ctrl.h>

static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg) {
    int *ret = arg;
    *ret = err->error;
    return NL_STOP;
}

static int finish_handler(struct nl_msg *msg, void *arg) {
    int *ret = arg;
    *ret = 0;
    return NL_SKIP;
}

static int scan_handler(struct nl_msg *msg, void *arg) {
    struct nlattr *tb[NL80211_ATTR_MAX+1];
    struct genlmsghdr *gnlh = nlmsg_data(nlmsg_hdr(msg));
    struct nlattr *nl_band;
    struct nlattr *nl_freq;
    struct nlattr *nl_rate;
    int rem_band, rem_freq, rem_rate;

    nla_parse(tb, NL80211_ATTR_MAX, genlmsg_attrdata(gnlh, 0), genlmsg_attrlen(gnlh, 0), NULL);

    if (!tb[NL80211_ATTR_SCAN_RESULTS])
        return NL_SKIP;

    nl_band = tb[NL80211_ATTR_SCAN_RESULTS];
    nla_for_each_nested(rem_band, nl_band, rem_freq) {
        nl_freq = nla_find_nested(rem_band, NL80211_BAND_ATTR_FREQ);
        if (nl_freq) {
            printf("Frequency: %d MHz\n", nla_get_u32(nl_freq));
        }
    }

    return NL_SKIP;
}

int main(int argc, char *argv[]) {
    struct nl_msg *msg;
    struct nl_sock *sk;
    int ret = -1;

    sk = nl_socket_alloc();
    if (!sk) {
        perror("Failed to allocate socket");
        return -1;
    }

    genl_connect(sk);

    struct genl_family *family = genl_ctrl_resolve(sk, "nl80211");
    if (!family) {
        perror("Failed to resolve nl80211 family");
        goto out;
    }

    msg = nlmsg_alloc();
    if (!msg) {
        perror("Failed to allocate message");
        goto out;
    }

    genlmsg_put(msg, 0, 0, family->id, 0, 0, NL80211_CMD_SCAN, 0);
    nlmsg_append(msg, genlmsg_attrdata(family->mgmt_genlhdr, 0), genlmsg_attrlen(family->mgmt_genlhdr, 0), NLMSG_ALIGNTO);

    nl_cb_set(msg, NL_CB_VALID, NL_CB_CUSTOM, scan_handler, NULL);
    nl_cb_set(msg, NL_CB_ACK, NL_CB_CUSTOM, finish_handler, &ret);
    nl_cb_err(msg, NL_CB_CUSTOM, error_handler, &ret);

    if (nl_send_auto(sk, msg) < 0) {
        perror("Failed to send message");
        goto out;
    }

    while (ret == -1)
        nl_recvmsgs(sk, msg);

out:
    nlmsg_free(msg);
    nl_socket_free(sk);

    return ret;
}