Parse IP header (src, dst)

main.py

@@ -1,6 +1,27 @@
 #!/usr/bin/env python3
 
 import pytun
+import struct
+import ipaddress
+
+class IpHeader:
+    def __init__(self, raw):
+        self.ver_ihl, \
+            self.tos, \
+            self.total_length, \
+            self.ident, \
+            self.flags_fragoffset, \
+            self.ttl, \
+            self.proto, \
+            self.chksum, \
+            src, \
+            dst, \
+            self.opt1, \
+            self.opt2, \
+            self.pad = struct.unpack('>BBHHHBBHIIHBB', raw)
+
+        self.src = ipaddress.IPv4Address(src)
+        self.dst = ipaddress.IPv4Address(dst)
 
 def main():
     tun_iface = pytun.TunTapDevice()
@@ -16,7 +37,18 @@ def main():
 
     while True:
         buf = tun_iface.read(tun_iface.mtu)
-        print(buf)
+
+        flags = buf[:2]
+        proto = buf[2:4]
+
+        if proto != b'\x08\x00':
+            continue
+
+        ip_header = IpHeader(buf[4:28])
+        body = buf[28:]
+
+        print(ip_header.src, '→', ip_header.dst, 'len: %d' % ip_header.total_length)
+
 
 if __name__ == '__main__':
     main()