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@AndrewFromMelbourne
Last active December 20, 2022 02:41
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wifi scanning code
// sudo apt-get install libiw-dev
//
// g++ -O3 -Wall wifiscan.cxx -o wifiscan -liw
#include <iwlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <cstdio>
#include <cstring>
//-------------------------------------------------------------------------
int main(void)
{
const char* interfaceName = "wlan0";
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1)
{
perror("socket");
exit(EXIT_FAILURE);
}
//---------------------------------------------------------------------
struct iw_range range;
if ((iw_get_range_info(sockfd, interfaceName, &range) < 0) ||
(range.we_version_compiled < 14))
{
printf("%s - interface doesn't support scanning\n", interfaceName);
exit(EXIT_FAILURE);
}
__u8 wev = range.we_version_compiled;
//---------------------------------------------------------------------
struct iwreq request;
request.u.param.flags = IW_SCAN_DEFAULT;
request.u.param.value = 0;
if (iw_set_ext(sockfd, interfaceName, SIOCSIWSCAN, &request) == -1)
{
perror("iw_set_ext(SIOCSIWSCAN)");
exit(EXIT_FAILURE);
}
//---------------------------------------------------------------------
struct timeval startTime;
struct timeval endTime;
struct timeval diffTime = { 0, 0 };
bool replyFound = false;
bool timeout = false;
char scanBuffer[0xFFFF];
gettimeofday(&startTime, NULL);
while ((replyFound == false) && (timeout == false))
{
memset(scanBuffer, 0, sizeof(scanBuffer));
request.u.data.pointer = scanBuffer;
request.u.data.length = sizeof(scanBuffer);
request.u.data.flags = 0;
int result = iw_get_ext(sockfd,
interfaceName,
SIOCGIWSCAN,
&request);
if (result == -1)
{
if (errno != EAGAIN)
{
perror("iw_get_ext(SICGIWSCAN)");
exit(EXIT_FAILURE);
}
}
if (result == 0)
{
replyFound = true;
}
gettimeofday(&endTime, NULL);
timersub(&endTime, &startTime, &diffTime);
if (diffTime.tv_sec > 10)
{
timeout = true;
}
else if (replyFound == false)
{
usleep(100000);
}
}
close(sockfd);
//---------------------------------------------------------------------
bool firstAP = true;
if (replyFound)
{
struct iw_event iwe;
struct stream_descr stream;
iw_init_event_stream(&stream,
scanBuffer,
request.u.data.length);
char eventBuffer[512];
while (iw_extract_event_stream(&stream, &iwe, wev) > 0)
{
switch(iwe.cmd)
{
case SIOCGIWAP:
{
const struct ether_addr *eap =
(const struct ether_addr *)iwe.u.ap_addr.sa_data;
iw_ether_ntop(eap, eventBuffer);
if (firstAP)
{
firstAP = false;
}
else
{
printf("\n");
}
printf("%s ", eventBuffer);
break;
}
case SIOCGIWFREQ:
{
double frequency = iw_freq2float(&(iwe.u.freq));
int channel = iw_freq_to_channel(frequency, &range);
if (frequency > 1.0)
{
frequency /= 1000000.0;
}
if (channel != -1)
{
printf("ch%02d ", channel);
}
break;
}
case SIOCGIWESSID:
{
char essid[IW_ESSID_MAX_SIZE+10];
memset(essid, '\0', sizeof(essid));
if((iwe.u.essid.pointer) && (iwe.u.essid.length))
{
memcpy(essid,
iwe.u.essid.pointer,
iwe.u.essid.length);
}
if(iwe.u.essid.flags)
{
if((iwe.u.essid.flags & IW_ENCODE_INDEX) > 1)
{
char encodeIndex[10];
sprintf(encodeIndex,
" [%d]",
iwe.u.essid.flags & IW_ENCODE_INDEX);
strcat(essid, encodeIndex);
}
}
else
{
strcpy(essid, "hidden");
}
printf("%s ", essid);
break;
}
case IWEVQUAL:
{
double signalQuality = (iwe.u.qual.qual * 100.0)
/ range.max_qual.qual;
printf("%.0f%% ", signalQuality);
if (iwe.u.qual.updated & IW_QUAL_RCPI)
{
double signalLevel = (iwe.u.qual.level / 2.0) - 110.0;
printf("%g dBm ", signalLevel);
}
else if (iwe.u.qual.updated & IW_QUAL_DBM)
{
int dbLevel = iwe.u.qual.level;
if (dbLevel >= 64)
{
dbLevel -= 0x100;
}
printf("%d dBm ", dbLevel);
}
else if ((iwe.u.qual.updated & IW_QUAL_LEVEL_INVALID) == 0)
{
printf("%d/%d ",
iwe.u.qual.level,
range.max_qual.level);
}
break;
}
default:
break;
}
}
}
if (firstAP == false)
{
printf("\n");
}
//---------------------------------------------------------------------
return 0;
}
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