nl80211_control.c

/*
    This file is part of LORCON

	The majority of the functions in this file were derived directly from the 
	'iw' tool (and are marked as such), (c) Johannes Berg

    LOROCN is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    LORCON is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with LORCON; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "config.h"
#include "lorcon.h"

#if defined(HAVE_LIBNL20) || defined(HAVE_LIBNL30) || defined(HAVE_LIBNLTINY)
#define HAVE_LIBNL_NG
#endif

#ifdef SYS_LINUX

#ifdef HAVE_LINUX_NETLINK
#include <sys/types.h>
#include <asm/types.h>

#ifdef HAVE_LIBNLTINY
#define _GNU_SOURCE
#endif

#include <netlink/genl/genl.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>

#include "nl80211.h"
#include <net/if.h>
#endif

#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include "nl80211_control.h"
#include "wifi_ht_channels.h"

// Libnl1->Libnl2 compatability mode since the API changed, cribbed from 'iw'
#if defined(HAVE_LIBNL10)

#define nl_sock nl_handle

static inline struct nl_handle *nl_socket_alloc(void) {
#ifdef HAVE_LINUX_NETLINK
	return nl_handle_alloc();
#else
    return NULL;
#endif
}

static inline void nl_socket_free(struct nl_sock *h) {
#ifdef HAVE_LINUX_NETLINK
	nl_handle_destroy(h);
#else
    return;
#endif
}

#endif


int ChanToFreq(int in_chan) {
    /* 802.11 channels to frequency; if it looks like a frequency, return as
     * pure frequency; derived from iwconfig */

    if (in_chan > 250)
        return in_chan;

    if (in_chan == 14)
        return 2484;
    else if (in_chan < 14)
        return 2407 + in_chan * 5;
    else if (in_chan >= 182 && in_chan <= 196)
        return 4000 + in_chan * 5;
    else
        return 5000 + in_chan * 5;

    return in_chan;
}

int FreqToChan(int in_freq) {
    if (in_freq < 250)
        return in_freq;

    /* revamped from iw */
    if (in_freq == 2484)
        return 14;

    if (in_freq < 2484)
        return (in_freq - 2407) / 5;

    return in_freq / 5 - 1000;
}

int nl80211_connect(const char *interface, void **nl_sock, 
        int *nl80211_id, int *if_index, char *errstr) {
#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX,
            "cannot connect to netlink; not compiled with netlink "
            "support.  Check the output of ./configure for more information");
    return -1;
#else

    if ((*if_index = if_nametoindex(interface)) < 0) {
        snprintf(errstr, LORCON_STATUS_MAX,
                "cannot connect to netlink:  Could not find interface '%s'", interface);
        return -1;
    }

    *nl_sock = nl_socket_alloc();
    if (!nl_sock) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to connect to netlink: could not allocate netlink socket");
        return -1;
    }

    if (genl_connect(*nl_sock)) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to connect to netlink: could not connect to generic netlink");
        return -1;
        nl_socket_free(*nl_sock);
    }

    *nl80211_id = genl_ctrl_resolve(*nl_sock, "nl80211");
    if (nl80211_id < 0) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to connect to netlink: could not resolve nl80211");
        nl_socket_free(*nl_sock);
    }

    return 0;
#endif
}

void nl80211_disconnect(void *nl_sock) {
    nl_socket_free(nl_sock);
}

int nl80211_createvif(const char *interface, const char *newinterface, 
        unsigned int *in_flags, unsigned int flags_sz, char *errstr) {
#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX, "Lorcon was not compiled with netlink/mac80211 "
            "support, check the output of ./configure for why");
    return -1;
#else

    void *nl_sock;
    int nl80211_id;

    struct nl_msg *msg;
    struct nl_msg *flags;

    unsigned int x;

    if (if_nametoindex(newinterface) > 0) 
        return 1;

    nl_sock = nl_socket_alloc();
    if (!nl_sock) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to create monitor vif %s:%s, unable to allocate netlink socket",
                interface, newinterface);
        return -1;
    }

    if (genl_connect(nl_sock)) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to create monitor vif %s:%s, unable to connect generic netlink",
                interface, newinterface);
        nl_socket_free(nl_sock);
    }

    nl80211_id = genl_ctrl_resolve(nl_sock, "nl80211");
    if (nl80211_id < 0) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to create monitor vif %s:%s, unable to resolve nl80211",
                interface, newinterface);
        nl_socket_free(nl_sock);
    }

    if ((msg = nlmsg_alloc()) == NULL) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to create monitor vif %s:%s, unable to allocate nl80211 "
                "message", interface, newinterface);
        nl_socket_free(nl_sock);
        return -1;
    }

    if ((flags = nlmsg_alloc()) == NULL) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to create monitor vif %s:%s, unable to allocate nl80211 flags",
                interface, newinterface);
        nl_socket_free(nl_sock);
        return -1;
    }

    genlmsg_put(msg, 0, 0, nl80211_id, 0, 0, NL80211_CMD_NEW_INTERFACE, 0);
    NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, if_nametoindex(interface));
    NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, newinterface);
    NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);

    for (x = 0; x < flags_sz; x++) {
        NLA_PUT_FLAG(flags, in_flags[x]);
    }
    
    if (flags_sz > 0)
        nla_put_nested(msg, NL80211_ATTR_MNTR_FLAGS, flags);

    if (nl_send_auto_complete(nl_sock, msg) < 0 || nl_wait_for_ack(nl_sock) < 0) {
nla_put_failure:
        snprintf(errstr, LORCON_STATUS_MAX, "failed to create monitor interface %s:%s",
                interface, newinterface);
        nl_socket_free(nl_sock);
        nlmsg_free(msg);
        nlmsg_free(flags);
        return -1;
    }

    nl_socket_free(nl_sock);
    nlmsg_free(msg);
    nlmsg_free(flags);

    if (if_nametoindex(newinterface) <= 0) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "creating a monitor interface for %s:%s worked, but couldn't"
                "find that interface after creation.", interface, newinterface);
        return -1;
    }

    return 0;
#endif
}

int nl80211_setchannel_cache(int ifindex, void *nl_sock,
        int nl80211_id, int channel, unsigned int chmode, char *errstr) {
#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX, "Lorcon was not compiled with netlink/mac80211 "
            "support, check the output of ./configure for why");
    return -1;
#else
    struct nl_msg *msg;
    int ret = 0;

    if (chmode >= 4) {
        snprintf(errstr, LORCON_STATUS_MAX, "unable to set channel: invalid channel mode");
        return -1;
    }

    if ((msg = nlmsg_alloc()) == NULL) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to set channel: unable to allocate mac80211 control message.");
        return -1;
    }

    genlmsg_put(msg, 0, 0, nl80211_id, 0, 0, NL80211_CMD_SET_WIPHY, 0);
    NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
    NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, ChanToFreq(channel));
    NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_CHANNEL_TYPE, chmode);

    if ((ret = nl_send_auto_complete(nl_sock, msg)) >= 0) {
        if ((ret = nl_wait_for_ack(nl_sock)) < 0) 
            goto nla_put_failure;
    }

    nlmsg_free(msg);

    return 0;

nla_put_failure:
    snprintf(errstr, LORCON_STATUS_MAX, 
            "unable to set channel %u/%u mode %u via mac80211: "
            "error code %d", channel, ChanToFreq(channel), chmode, ret);
    nlmsg_free(msg);
    return ret;
#endif
}

int nl80211_set_channel(const char *interface, int channel, 
        unsigned int chmode, char *errstr) {
#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX, "Lorcon was not compiled with netlink/mac80211 "
            "support, check the output of ./configure for why");
    return -1;
#else
    void *nl_sock;
    int nl80211_id;
    int ifidx;

    if (nl80211_connect(interface, &nl_sock, &nl80211_id, &ifidx, errstr) < 0)
        return -1;

    int ret = 
        nl80211_setchannel_cache(ifidx, nl_sock, nl80211_id, channel, chmode, errstr);

    nl80211_disconnect(nl_sock);

    return ret;
#endif
}

int nl80211_setfrequency_cache(int ifindex, void *nl_sock, int nl80211_id, 
        unsigned int control_freq, unsigned int chan_width, 
        unsigned int center_freq1, unsigned int center_freq2,
        char *errstr) {
#ifndef HAVE_LINUX_NETLINK
	snprintf(errstr, LORCON_STATUS_MAX, "Lorcon was not compiled with netlink/mac80211 "
			 "support, check the output of ./configure for why");
    return -1;
#else
    struct nl_msg *msg;
    int ret = 0;

    if ((msg = nlmsg_alloc()) == NULL) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "unable to set channel/frequency: unable to allocate "
                "mac80211 control message.");
        return -1;
    }

    genlmsg_put(msg, 0, 0, nl80211_id, 0, 0, NL80211_CMD_SET_WIPHY, 0);
    NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
    NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, control_freq);
    NLA_PUT_U32(msg, NL80211_ATTR_CHANNEL_WIDTH, chan_width);

    if (center_freq1 != 0) {
        NLA_PUT_U32(msg, NL80211_ATTR_CENTER_FREQ1, center_freq1);
    }

    if ((ret = nl_send_auto_complete(nl_sock, msg)) >= 0) {
        if ((ret = nl_wait_for_ack(nl_sock)) < 0) 
            goto nla_put_failure;
    }

    nlmsg_free(msg);

    return 0;

nla_put_failure:
	snprintf(errstr, LORCON_STATUS_MAX, 
            "unable to set frequency %u %u %u via mac80211: error code %d",
            control_freq, chan_width, center_freq1, ret);
	nlmsg_free(msg);
	return ret;
#endif
}

int nl80211_setfrequency(const char *interface, 
        unsigned int control_freq, unsigned int chan_width,
        unsigned int center_freq1, unsigned int center_freq2,
        char *errstr) {
#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX, "Lorcon was not compiled with netlink/mac80211 "
            "support, check the output of ./configure for why");
    return -1;
#else
    void *nl_sock;
    int ifidx;
    int nl80211_id;

    if (nl80211_connect(interface, &nl_sock, &nl80211_id, &ifidx, errstr) < 0) {
        return -1;
    }

    int ret = 
        nl80211_setfrequency_cache(ifidx, nl_sock, nl80211_id, 
                control_freq, chan_width, center_freq1, center_freq2, errstr);

    nl80211_disconnect(nl_sock);

    return ret;
#endif
}

struct nl80211_channel_list {
    /* Should be a string once we support ht/vht */
    int channel;
    struct nl80211_channel_list *next;
};

struct nl80211_channel_block {
	char *phyname;

	int nfreqs;

    struct nl80211_channel_list *channel_list;
    struct nl80211_channel_list *chan_list_last;
};


#ifdef HAVE_LINUX_NETLINK
static int nl80211_freqlist_cb(struct nl_msg *msg, void *arg) {
    struct nlattr *tb_msg[NL80211_ATTR_MAX + 1];
    struct genlmsghdr *gnlh = (struct genlmsghdr *) nlmsg_data(nlmsg_hdr(msg));
    struct nlattr *tb_band[NL80211_BAND_ATTR_MAX + 1];
    struct nlattr *tb_freq[NL80211_FREQUENCY_ATTR_MAX + 1];
    struct nlattr *nl_band, *nl_freq;
    int rem_band, rem_freq;
    uint32_t freq;
    struct nl80211_channel_block *chanb = (struct nl80211_channel_block *) arg;
    char channel_str[32];
    int band_ht40, band_ht80, band_ht160;
    unsigned int hti;

    struct nl80211_channel_list *chan_list_new;

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

    if (tb_msg[NL80211_ATTR_WIPHY_NAME]) {
        if (strcmp(nla_get_string(tb_msg[NL80211_ATTR_WIPHY_NAME]), chanb->phyname) != 0) {
            return NL_SKIP;
        }
    }

    if (tb_msg[NL80211_ATTR_WIPHY_BANDS]) {
        nla_for_each_nested(nl_band, tb_msg[NL80211_ATTR_WIPHY_BANDS], rem_band) {
            band_ht40 = band_ht80 = band_ht160 = 0;

            nla_parse(tb_band, NL80211_BAND_ATTR_MAX, nla_data(nl_band),
                    nla_len(nl_band), NULL);

            /* If we have a HT capability field, examine it for HT40 */
            if (tb_band[NL80211_BAND_ATTR_HT_CAPA]) {
                __u16 cap = nla_get_u16(tb_band[NL80211_BAND_ATTR_HT_CAPA]);

                /* bit 1 is the HT40 bit */
                if (cap & (1 << 1))
                    band_ht40 = 1;
            }

            /* If we have a VHT field, we can assume we have HT80 and then we need
             * to examine ht160.  
             * TODO: figure out 160 80+80; do all devices that support 80+80 support
             * 160?  For now we assume they do...
             */
            if (tb_band[NL80211_BAND_ATTR_VHT_CAPA]) {
                band_ht80 = 1;

                __u16 cap = nla_get_u32(tb_band[NL80211_BAND_ATTR_VHT_CAPA]);

                if (((cap >> 2) & 3) == 1) {
                    band_ht160 = 1;
                } else if (((cap >> 2) & 3) == 2) {
                    band_ht160 = 1;
                }
            }

            // fprintf(stderr, "debug - %u %u %u\n", band_ht40, band_ht80, band_ht160);

            if (tb_band[NL80211_BAND_ATTR_FREQS]) {
                nla_for_each_nested(nl_freq, tb_band[NL80211_BAND_ATTR_FREQS], rem_freq) {
                    nla_parse(tb_freq, NL80211_FREQUENCY_ATTR_MAX, nla_data(nl_freq),
                            nla_len(nl_freq), NULL);

                    if (!tb_freq[NL80211_FREQUENCY_ATTR_FREQ])
                        continue;

                    if (tb_freq[NL80211_FREQUENCY_ATTR_DISABLED])
                        continue;

                    /* We've got at least one actual frequency */
                    freq = nla_get_u32(tb_freq[NL80211_FREQUENCY_ATTR_FREQ]);

                    chan_list_new = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));

                    /* Ultimately channels will be strings to support HT/VHT
                    snprintf(channel_str, 32, "%u", mac80211_freq_to_chan(freq));
                    chan_list_new->channel = strdup(channel_str);
                    */
                    chan_list_new->channel = ChanToFreq(freq);

                    chan_list_new->next = NULL;
                    chanb->nfreqs++;
                    chanb->chan_list_last->next = chan_list_new;
                    chanb->chan_list_last = chan_list_new;

#if 0
                    /* This code from Kismet handles HT/VHT channels but we don't have
                     * the infrastructure yet in lorcon to treat channels as strings,
                     * so just def it out for now */

                    /* Look us up in the wifi_ht_channels list and add channels if we
                     * need to add HT capabilities.  We could convert this to a channel
                     * but it's better to do a frequency lookup */
                    for (hti = 0; hti < MAX_WIFI_HT_CHANNEL; hti++) {
                        if (wifi_ht_channels[hti].freq == freq) {
                            if (band_ht40) {
                                if (wifi_ht_channels[hti].flags & WIFI_HT_HT40MINUS) {
                                    chan_list_new = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));
                                    snprintf(channel_str, 32, 
                                            "%uHT40-", mac80211_freq_to_chan(freq));
                                    chan_list_new->channel = strdup(channel_str);

                                    chan_list_new->next = NULL;
                                    chanb->nfreqs++;
                                    chanb->chan_list_last->next = chan_list_new;
                                    chanb->chan_list_last = chan_list_new;
                                }

                                if (wifi_ht_channels[hti].flags & WIFI_HT_HT40PLUS) {
                                    chan_list_new = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));

                                    snprintf(channel_str, 32, 
                                            "%uHT40+", mac80211_freq_to_chan(freq));
                                    chan_list_new->channel = strdup(channel_str);

                                    chan_list_new->next = NULL;
                                    chanb->nfreqs++;
                                    chanb->chan_list_last->next = chan_list_new;
                                    chanb->chan_list_last = chan_list_new;
                                }
                            }

                            if (band_ht80 && wifi_ht_channels[hti].flags & WIFI_HT_HT80) {
                                chan_list_new = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));
                                snprintf(channel_str, 32, 
                                        "%uVHT80", mac80211_freq_to_chan(freq));
                                chan_list_new->channel = strdup(channel_str);

                                chan_list_new->next = NULL;
                                chanb->nfreqs++;
                                chanb->chan_list_last->next = chan_list_new;
                                chanb->chan_list_last = chan_list_new;
                            }

                            if (band_ht160 && wifi_ht_channels[hti].flags & WIFI_HT_HT160) {
                                chan_list_new = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));
                                snprintf(channel_str, 32, 
                                        "%uVHT160", mac80211_freq_to_chan(freq));
                                chan_list_new->channel = strdup(channel_str);

                                chan_list_new->next = NULL;
                                chanb->nfreqs++;
                                chanb->chan_list_last->next = chan_list_new;
                                chanb->chan_list_last = chan_list_new;
                            }

                            break;
                        }
                    }
#endif
                }
            }
        }
    }

    return NL_SKIP;
}
#endif

#ifdef HAVE_LINUX_NETLINK
static int nl80211_error_cb(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg) {
	int *ret = (int *) arg;
	*ret = err->error;
	return NL_STOP;
}

static int nl80211_finish_cb(struct nl_msg *msg, void *arg) {
	int *ret = (int *) arg;
	*ret = 0;
	return NL_SKIP;
}

static int nl80211_ack_cb(struct nl_msg *msg, void *arg) {
    int *ret = arg;
    *ret = 0;
    return NL_STOP;
}
#endif

int nl80211_get_chanlist(const char *interface, int *ret_num_chans, int **ret_chan_list,
        char *errstr) {
    struct nl80211_channel_block cblock = {
        .phyname = NULL,
        .nfreqs = 0,
        .channel_list = NULL,
        .chan_list_last = NULL
    };

    unsigned int num_freq;
    struct nl80211_channel_list *chan_list_cur, *chan_list_old;

#ifndef HAVE_LINUX_NETLINK
    snprintf(errstr, LORCON_STATUS_MAX, "Kismet was not compiled with netlink/nl80211 "
            "support, check the output of ./configure for why");
    return -1;
#else

    void *nl_sock;
    int nl80211_id;

    struct nl_cb *cb;
    int err;
    struct nl_msg *msg;

    cblock.phyname = nl80211_find_parent(interface);
    if (strlen(cblock.phyname) == 0) {
        if (if_nametoindex(interface) <= 0) {
            snprintf(errstr, LORCON_STATUS_MAX, 
                    "failed to get channels from interface '%s': interface does "
                    "not exist.", interface);
            return -1;
        } 

        snprintf(errstr, LORCON_STATUS_MAX, 
                "failed to find parent phy interface for interface '%s': interface "
                "may not be a mac80211 wifi device?", interface);
        return -1;
    }

    nl_sock = nl_socket_alloc();
    if (!nl_sock) {
        snprintf(errstr, LORCON_STATUS_MAX, "FATAL: Failed to allocate netlink socket");
        return -1;
    }

    if (genl_connect(nl_sock)) {
        snprintf(errstr, LORCON_STATUS_MAX, "FATAL: Failed to connect to generic netlink");
        nl_socket_free(nl_sock);
    }

    nl80211_id = genl_ctrl_resolve(nl_sock, "nl80211");
    if (nl80211_id < 0) {
        snprintf(errstr, LORCON_STATUS_MAX, "FATAL: Failed to resolve nl80211");
        nl_socket_free(nl_sock);
    }

    msg = nlmsg_alloc();

    cb = nl_cb_alloc(NL_CB_DEFAULT);

    err = 1;

    nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, nl80211_freqlist_cb, &cblock);
	nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, nl80211_ack_cb, &err);
    nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, nl80211_finish_cb, &err);
    nl_cb_err(cb, NL_CB_CUSTOM, nl80211_error_cb, &err);

    genlmsg_put(msg, 0, 0, nl80211_id, 0, NLM_F_DUMP, NL80211_CMD_GET_WIPHY, 0);

    /* Initialize the empty first channel list item */
    cblock.channel_list = (struct nl80211_channel_list *) malloc(sizeof(struct nl80211_channel_list));
    cblock.channel_list->channel = 0;
    /*
    cblock.channel_list->channel = NULL;
    */
    cblock.channel_list->next = NULL;
    cblock.chan_list_last = cblock.channel_list;

    if (nl_send_auto_complete((struct nl_sock *) nl_sock, msg) < 0) {
        snprintf(errstr, LORCON_STATUS_MAX, 
                "failed to fetch channels from interface '%s': failed to "
                "write netlink command", interface);
        nlmsg_free(msg);
        nl_cb_put(cb);
        nl_socket_free(nl_sock);
        return -1;
    }

    while (err)
        nl_recvmsgs((struct nl_sock *) nl_sock, cb);

    nl_cb_put(cb);
    nlmsg_free(msg);
    nl_socket_free(nl_sock);

    /* Convert our linked list into a channel block */

    (*ret_num_chans) = cblock.nfreqs;
    (*ret_chan_list) = malloc(sizeof(char *) * cblock.nfreqs);

    num_freq = 0;

    /* Skip the first item which is our placeholder */
    chan_list_cur = cblock.channel_list->next;

    while (chan_list_cur != NULL && num_freq < cblock.nfreqs) {
        /* Use the dup'd string directly */
        (*ret_chan_list)[num_freq++] = chan_list_cur->channel;

        // fprintf(stderr, "debug - %u %s\n", num_freq, chan_list_cur->channel);

        /* Shuffle the pointers */
        chan_list_old = chan_list_cur;
        chan_list_cur = chan_list_cur->next;
        free(chan_list_old);
    }

    /* If we didn't process all the channels before we hit the end of the list... */
    if (chan_list_cur != NULL || num_freq != cblock.nfreqs) {
        fprintf(stderr, "ERROR - linux_netlink_control miscalculated the number of "
                "channels somehow...\n");

        /* Clean up list overrun */
        while (chan_list_cur != NULL) {
            chan_list_old = chan_list_cur;
            chan_list_cur = chan_list_cur->next;
            free(chan_list_old);
        }

        /* Clean up list underrun */
        for ( ; num_freq < cblock.nfreqs; num_freq++) {
            /*
            (*ret_chan_list)[num_freq] = NULL;
            */
            (*ret_chan_list)[num_freq] = 0;
        }
    }

    /* remove the list head ptr */
    free(cblock.channel_list);
    /* Remove the phyname */
    free(cblock.phyname);

    return (*ret_num_chans);
#endif
}

char *nl80211_find_parent(const char *interface) {
	DIR *devdir;
	struct dirent *devfile;
	char dirpath[1024];
	char *ret;

	DIR *ieeedir;
	struct dirent *ieeefile;
	char ieeedirpath[1024];

	snprintf(dirpath, 1024, "/sys/class/net/%s/phy80211/device", interface);

	if ((devdir = opendir(dirpath)) == NULL)
		return NULL;

	while ((devfile = readdir(devdir)) != NULL) {
		if (strlen(devfile->d_name) < 9)
			continue;

		if (strncmp("ieee80211:phy", devfile->d_name, 13) == 0) {
			ret = strdup(devfile->d_name + 10);
			closedir(devdir);
			return ret;
		}

        if (strncmp("ieee80211", devfile->d_name, 9) == 0) {
			snprintf(ieeedirpath, 1024, "%s/ieee80211", dirpath);

            if ((ieeedir = opendir(ieeedirpath)) != NULL) {
                while ((ieeefile = readdir(ieeedir)) != NULL) {
                    if (strncmp("phy", ieeefile->d_name, 3) == 0) {
                        ret = strdup(ieeefile->d_name);

                        closedir(ieeedir);
                        closedir(devdir);

                        return ret;
                    }
                }
            }

            closedir(ieeedir);
        }
	}

	closedir(devdir);

	return NULL;
}

#endif /* SYS_LINUX */