Content gets corrupted when I forward a scapy packet using the Rest Service

asked 2014-08-08 06:37:37 -0700

updated 2014-08-08 06:41:51 -0700

I am trying to forward a network packet formed by scapy to the rest service, but somehow packet gets corrupted at receiver side (rest service side).

I formed the network packet using scapy:

0000  1a 0b 0c 14 05 16 00 00 00 00 00 00 08 00 45 00   ..............E.
0010  01 10 00 01 00 00 40 11 f0 d2 05 05 05 04 7f 00   ......@.........
0020  00 01 00 44 00 43 00 fc 85 7f 01 00 00 00 00 00   ...D.C..........
0030  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0040  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0050  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0060  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0070  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0080  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0090  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00a0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00b0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00c0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00d0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00e0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00f0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0100  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0110  00 00 00 00 00 00 63 82 53 63 35 01 01 ff         ......c.Sc5...

I forwarded the framed scapy packet to web service using python code :

h = httplib2.Http(".cache")
h.add_credentials("user","passworkd")
data = urllib.urlencode({"packet":pack})
resp, content = h.request(url, "POST", data, headers={'Content-Type': 'applicatoin/x-www-form-urlencode'})

At the server side(implemented in java) I printed the obtained packet(byte stream) it shows the following output (which is different from the send packet) :

1a0b0c140516000000000000080045000110000100004011efbfbdefbfbd050505047f0000010044004300efbfbd7f010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000063efbfbd5363350101efbfbd

Java server side handling :

@Path("/test")
    @POST
    @StatusCodes({
        @ResponseCode(code = 200, condition = "Destination reachable"),
        @ResponseCode(code = 503, condition = "Internal error"),
        @ResponseCode(code = 503, condition = "Destination unreachable") })
    public Response rcvDHCPPkt(@FormParam("packet") String packet) {

        String pkt_decode = URLDecoder.decode(packet, "UTF-8"); // tried with and without it.

        // here it shows the packet corruption. I tried to print packet also it has same problem.
        System.out.println("packet received:" + byteArrayToHex(packet_decode.getBytes()));

used following function to print the hex equivalent.

public static String byteArrayToHex(byte[] a) {
               StringBuilder sb = new StringBuilder(a.length * 2);
               for(byte b: a)
                  sb.append ...
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