core/parse: Better handling of Radiotap information

Radiotap information is now stored in the `libwifi_frame` struct, and will
be kept automatically in `libwifi_frame.radiotap_info` for the lifecycle of
said frame, if it is present.

A new flag has been added for the frame for use with `libwifi_frame.flags`
to detect if the radiotap info is present: `LIBWIFI_FLAGS_RADIOTAP_PRESENT`.

The frame parser will now automatically calculate the band and center channel
from radiotap data, and will store them in `libwifi_radiotap_info.channel.center`
and `libwifi_radiotap_info.channel.band`.

Four new flags have been added for use with the new radiotap band field:
- `LIBWIFI_RADIOTAP_BAND_2GHZ`
- `LIBWIFI_RADIOTAP_BAND_5GHZ`
- `LIBWIFI_RADIOTAP_BAND_6GHZ`
- `LIBWIFI_RADIOTAP_BAND_900MHZ`

These can be used with a binary AND:
`if (rtap.channel.band & LIBWIFI_RADIOTAP_BAND_6GHZ) { }`

4 files changed, 36 insertions, 3 deletions

@@ -32,8 +32,7 @@
  *  - QoS Data Frames
  *  - Control Frames
  */
-int libwifi_get_wifi_frame(struct libwifi_frame *fi, const unsigned char *frame, size_t frame_len,
-                           int radiotap) {
+int libwifi_get_wifi_frame(struct libwifi_frame *fi, const unsigned char *frame, size_t frame_len, int radiotap) {
     union libwifi_frame_header fh = {0};
     size_t header_len = 0;
     size_t frame_data_len = frame_len;
@@ -55,6 +54,10 @@ int libwifi_get_wifi_frame(struct libwifi_frame *fi, const unsigned char *frame,
             fi->flags |= LIBWIFI_FLAGS_FCS_PRESENT;
             frame_data_len -= sizeof(uint32_t); // FCS is 4 bytes wide
         }
+
+        fi->flags |= LIBWIFI_FLAGS_RADIOTAP_PRESENT;
+        fi->radiotap_info = malloc(sizeof(struct libwifi_radiotap_info));
+        memcpy(fi->radiotap_info, &rtap_info, sizeof(struct libwifi_radiotap_info));
     }
 
     struct libwifi_frame_ctrl *frame_control = (struct libwifi_frame_ctrl *) frame_data;
@@ -134,5 +137,6 @@ int libwifi_get_wifi_frame(struct libwifi_frame *fi, const unsigned char *frame,
 }
 
 void libwifi_free_wifi_frame(struct libwifi_frame *fi) {
+    free(fi->radiotap_info);
     free(fi->body);
 }
@@ -17,6 +17,7 @@
 #define LIBWIFI_CORE_FRAME_H
 
 #include "../../core/misc/byteswap.h"
+#include "../../core/misc/radiotap.h"
 
 #include <stdint.h>
 #include <sys/types.h>
@@ -25,6 +26,7 @@
 #define LIBWIFI_FLAGS_FCS_PRESENT (1 << 0)
 #define LIBWIFI_FLAGS_IS_QOS (1 << 1)
 #define LIBWIFI_FLAGS_IS_ORDERED (1 << 2)
+#define LIBWIFI_FLAGS_RADIOTAP_PRESENT (1 << 3)
 
 /* Defined frame types and sub-types */
 enum libwifi_frame_type {
@@ -306,6 +308,7 @@ union libwifi_mgmt_frame_header {
  * frame in libwifi.
  */
 struct libwifi_frame {
+    struct libwifi_radiotap_info *radiotap_info;
     uint16_t flags;
     struct libwifi_frame_ctrl frame_control;
     size_t len;
@@ -21,13 +21,22 @@
 #define LIBWIFI_MAX_RADIOTAP_LEN 128
 #define LIBWIFI_MAX_RADIOTAP_ANTENNAS 16
 
+#define LIBWIFI_RADIOTAP_BAND_2GHZ (1 << 0)
+#define LIBWIFI_RADIOTAP_BAND_5GHZ (1 << 1)
+#define LIBWIFI_RADIOTAP_BAND_6GHZ (1 << 2)
+#define LIBWIFI_RADIOTAP_BAND_900MHZ (1 << 3)
+
 /**
  * A channel field in radiotap consists of a 2-byte wide flags
- * sub-field and a 2-byte wide frequency field
+ * sub-field and a 2-byte wide frequency field.
+ *
+ * libwifi will also calculate the band and center channel.
  */
 struct libwifi_radiotap_channel {
     uint16_t flags;
     uint16_t freq;
+    uint8_t center;
+    uint8_t band;
 } __attribute__((packed));
 
 /**
@@ -47,6 +47,23 @@ int libwifi_parse_radiotap_info(struct libwifi_radiotap_info *info, const unsign
             case IEEE80211_RADIOTAP_CHANNEL:
                 info->channel.freq = le16toh(*(uint16_t *) it.this_arg);
                 info->channel.flags = le16toh(*(uint16_t *) (it.this_arg + 2));
+
+                // Handle band and channel
+                if (info->channel.freq >= 2412 && info->channel.freq <= 2484) {
+                    info->channel.band |= LIBWIFI_RADIOTAP_BAND_2GHZ;
+                    if (info->channel.freq == 2484) {
+                        info->channel.center = 14;
+                    } else {
+                        info->channel.center = (info->channel.freq - 2407) / 5;
+                    }
+                } else if (info->channel.freq >= 5160 && info->channel.freq <= 5885) {
+                    info->channel.band |= LIBWIFI_RADIOTAP_BAND_5GHZ;
+                    info->channel.center = (info->channel.freq - 5000) / 5;
+                } else if (info->channel.freq >= 5955 && info->channel.freq <= 7115) {
+                    info->channel.band |= LIBWIFI_RADIOTAP_BAND_6GHZ;
+                    info->channel.center = (info->channel.freq - 5950) / 5;
+                }
+
                 break;
             case IEEE80211_RADIOTAP_RATE:
                 info->rate_raw = *it.this_arg;