/* Given the tagged parameter sets from a beacon packet, locate the AP's SSID and return its current channel number */
int parse_beacon_tags(const u_char *packet, size_t len)
{
char *ssid = NULL;
const u_char *tag_data = NULL;
unsigned char *ie = NULL, *channel_data = NULL;
size_t ie_len = 0, ie_offset = 0, tag_len = 0, tag_offset = 0;
int channel = 0;
struct radio_tap_header *rt_header = NULL;
rt_header = (struct radio_tap_header *) radio_header(packet, len);
tag_offset = rt_header->len + sizeof(struct dot11_frame_header) + sizeof(struct beacon_management_frame);
if(tag_offset < len)
{
tag_len = (len - tag_offset);
tag_data = (const u_char *) (packet + tag_offset);
/* If no SSID was manually specified, parse and save the AP SSID */
if(get_ssid() == NULL)
{
ie = parse_ie_data(tag_data, tag_len, (uint8_t) SSID_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
/* Return data is not null terminated; allocate ie_len+1 and memcpy string */
ssid = malloc(ie_len+1);
if(ssid)
{
memset(ssid, 0, (ie_len+1));
memcpy(ssid, ie, ie_len);
set_ssid(ssid);
free(ssid);
}
free(ie);
}
}
ie = parse_ie_data(tag_data, tag_len, (uint8_t) RATES_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
set_ap_rates(ie, ie_len);
free(ie);
}
channel_data = parse_ie_data(tag_data, tag_len, (uint8_t) CHANNEL_TAG_NUMBER, &ie_len, &ie_offset);
if(channel_data)
{
if(ie_len == 1)
{
memcpy((int *) &channel, channel_data, ie_len);
}
free(channel_data);
}
}
return channel;
}
/* Given the tagged parameter sets from a beacon packet, locate the AP's SSID and return its current channel number */
int parse_beacon_tags(const unsigned char *packet, size_t len)
{
set_vendor(0, "\0\0\0");
char *ssid = NULL;
const unsigned char *tag_data = NULL;
unsigned char *ie = NULL, *channel_data = NULL;
size_t ie_len = 0, ie_offset = 0, tag_len = 0, tag_offset = 0;
int channel = 0;
struct radio_tap_header *rt_header = NULL;
rt_header = (struct radio_tap_header *) radio_header(packet, len);
tag_offset = end_le16toh(rt_header->len) + sizeof(struct dot11_frame_header) + sizeof(struct beacon_management_frame);
if(tag_offset < len)
{
tag_len = (len - tag_offset); /* this actually denotes length of the entire tag data area */
tag_data = (const unsigned char *) (packet + tag_offset);
/* If no SSID was manually specified, parse and save the AP SSID */
if(get_ssid() == NULL)
{
ie = parse_ie_data(tag_data, tag_len, (uint8_t) SSID_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
/* Return data is not null terminated; allocate ie_len+1 and memcpy string */
ssid = malloc(ie_len+1);
if(ssid)
{
memset(ssid, 0, (ie_len+1));
memcpy(ssid, ie, ie_len);
set_ssid(ssid);
free(ssid);
}
free(ie);
}
}
ie = parse_ie_data(tag_data, tag_len, HT_CAPS_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
set_ap_htcaps(ie, ie_len);
free(ie);
}
ie = parse_ie_data(tag_data, tag_len, (uint8_t) RATES_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
set_ap_rates(ie, ie_len);
free(ie);
}
ie = parse_ie_data(tag_data, tag_len, (uint8_t) ERATES_TAG_NUMBER, &ie_len, &ie_offset);
if(ie)
{
set_ap_ext_rates(ie, ie_len);
free(ie);
}
channel_data = parse_ie_data(tag_data, tag_len, (uint8_t) CHANNEL_TAG_NUMBER, &ie_len, &ie_offset);
if(channel_data)
{
if(ie_len == 1)
{
channel = *(uint8_t*)channel_data;
}
free(channel_data);
}
size_t ie_iterator = 0;
do {
const unsigned char *tag = tag_data + ie_iterator;
// check for the length of the tag, and that its not microsoft
if(tag[0] == VENDOR_SPECIFIC_TAG &&
ie_iterator+2+3 < tag_len &&
((tag[1] < 11 && memcmp(tag+2, "\x00\x14\x6c", 3) && memcmp(tag+2, "\x00\x50\xf2", 3)) ||
(tag[1] == 30 && !(memcmp(tag+2, "\x00\x26\x86", 3))))) {
set_vendor(1, tag + 2);
break;
}
} while(get_next_ie(tag_data, tag_len, &ie_iterator));
}
return channel;
}
