partially parse radiotap header to get proper offset for contents

README.md

@@ -46,3 +46,6 @@ Espressif only ships a binary blob and header file.
 * [IPv4 Header](https://en.wikipedia.org/wiki/Internet_Protocol_version_4)
 * [UDP Datagram structure](https://en.wikipedia.org/wiki/User_Datagram_Protocol#UDP_datagram_structure)
 * [Universal TUN/TAP device driver](https://www.kernel.org/doc/html/latest/networking/tuntap.html)
+
+### Radiotap
+* [radiotap.org](https://www.radiotap.org/)

include/ifnow_now.h

@@ -12,7 +12,7 @@
 #define ERR_BIND_FAILED   (-3)
 #define ERR_FILTER_FAILED (-4)
 
-typedef int (*ifnow_now_receive_cb)(void *now_cfg, uint8_t *buf, uint32_t len);
+typedef int (*ifnow_now_receive_cb)(void *now_cfg, uint8_t *buf, ssize_t len);
 
 typedef struct {
   int fd_if_socket;

src/main.c

@@ -1,5 +1,5 @@
 #include <stdio.h>
-#include <strings.h>
+#include <string.h>
 #include <stdint.h>
 
 #include "ifnow.h"
@@ -33,7 +33,7 @@ char *color_chart[] = {
 };
 uint8_t color_size = 15;
 
-int ifnow_now_receive_callback(void *cfg, uint8_t *buf, uint32_t len) {
+int ifnow_now_receive_callback(void *cfg, uint8_t *buf, ssize_t len) {
   ifnow_now_cfg_t *now_cfg = cfg;
 
   printf("NOW receive_count: %d\n", len);
@@ -43,12 +43,22 @@ int ifnow_now_receive_callback(void *cfg, uint8_t *buf, uint32_t len) {
   }
   printf("\n");
 
+  struct IEEE80211_radiotap radiotap;
+  struct IEEE80211_wlan wlan;
+
+  memcpy(&radiotap, buf, sizeof(struct IEEE80211_radiotap));
+  memcpy(&wlan, buf + radiotap.length, len - radiotap.length);
+
   // TODO apply buf to actual structs of headers
-  uint8_t bp = 57;
+  uint8_t bp = radiotap.length + 24 + 7 + 8;
-  int err = ifnow_tun_send(&tun_cfg, buf + bp, len - bp);
+
+  int err = ifnow_tun_send(&tun_cfg, buf + bp, len - bp - 4);
+
   if(err < 0) {
     perror("Failed to send over tunnel");
   }
+
+  return err;
 }
 
 int ifnow_tun_receive_callback(void *cfg, uint8_t *buf, uint32_t len) {

src/now.c

@@ -55,7 +55,7 @@ void *ifnow_thread_handle(void *arg) {
     receive_count = recv(now_cfg->fd_if_socket, receive_buffer, IFNOW_MAX_RECEIVE, MSG_TRUNC);
 
     if(receive_count > 0 && now_cfg->receive != NULL) {
-      now_cfg->receive(now_cfg, receive_buffer, receive_count);
+      now_cfg->receive(now_cfg, (uint8_t*)&receive_buffer, receive_count);
     }
   }
 }