sniffer added

camera_streaming/sniffing/sniffer.py

+#! /usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import binascii
+import json
+import subprocess as sub
+
+CMD = (
+    'sudo tshark -i wlan0 -Y'.split() +
+    ["frame contains \"MEEETADATA\""] +
+    '-T fields -e data'.split()
+)
+
+p = sub.Popen(CMD, stdout=sub.PIPE)
+for row in iter(p.stdout.readline, b''):
+    packet = binascii.unhexlify(row.rstrip())
+
+    FRAME_IDENT = b"MEEETADATA"
+
+    s = packet.find(FRAME_IDENT)
+    if s == -1:
+        continue
+
+    data_start = s+len(FRAME_IDENT)+1
+    data_len = packet[data_start-1]
+    data_str = packet[data_start:data_start+data_len]
+
+    data = json.loads(data_str)
+    print("!", data)