Add script to convert wpa_supplicant debug output to pcap

For debugging I needed to look at the frames in a wpa_supplicant debug
log. Looking at the hexdump is a bit tedious, so I wrote a quick script
to convert the nl80211 debugging output to a PCAP file that can be
opened in wireshark.

I've polished the initial raw script a bit to add error messages and to
also record the timestamps to the pcap file.

Hopefully it's useful to somebody else as well.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

wpa_supplicant/utils/log2pcap.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2012, Intel Corporation
+#
+# Author: Johannes Berg <johannes@sipsolutions.net>
+#
+# This software may be distributed under the terms of the BSD license.
+# See README for more details.
+
+import sys, struct, re
+
+def write_pcap_header(pcap_file):
+    pcap_file.write(
+        struct.pack('<IHHIIII',
+                    0xa1b2c3d4, 2, 4, 0, 0, 65535,
+                    105 # raw 802.11 format
+                    ))
+
+def pcap_addpacket(pcap_file, ts, data):
+    # ts in seconds, float
+    pcap_file.write(struct.pack('<IIII',
+        int(ts), int(1000000 * ts) % 1000000,
+        len(data), len(data)))
+    pcap_file.write(data)
+
+if __name__ == "__main__":
+    try:
+        input = sys.argv[1]
+        pcap = sys.argv[2]
+    except IndexError:
+        print "Usage: %s <log file> <pcap file>" % sys.argv[0]
+        sys.exit(2)
+
+    input_file = open(input, 'r')
+    pcap_file = open(pcap, 'w')
+    frame_re = re.compile(r'(([0-9]+.[0-9]{6}):\s*)?nl80211: MLME event frame - hexdump\(len=[0-9]*\):((\s*[0-9a-fA-F]{2})*)')
+
+    write_pcap_header(pcap_file)
+
+    for line in input_file:
+        m = frame_re.match(line)
+        if m is None:
+            continue
+        if m.group(2):
+            ts = float(m.group(2))
+        else:
+            ts = 0
+        hexdata = m.group(3)
+        hexdata = hexdata.split()
+        data = ''.join([chr(int(x, 16)) for x in hexdata])
+        pcap_addpacket(pcap_file, ts, data)
+
+    input_file.close()
+    pcap_file.close()