Re: [Discuss-gnuradio] file source with gr-ieee802.11 tx

[Jason Matusiak]

> The transceiver wraps your payload in some headers that add stuff like MAC 
> address, frame type, and CRC. 
> These are the minimum fields that are required so that a WiFi card actually 
> accepts the frame.

Makes sense.  I knew about the headers and CRC, but I wasn't even
thinking about it being used with an actual WiFi device (as opposed to
two USRPs).

> There is currently no option to dump raw bytes, but its a trivial 
> modification of the Wireshark block (dump 
> without a PCAP header).

This sounds reasonable to me, but so far I have been unsuccesful.  I am
attempting to edit wireshark_connector_impl.cc, but none of my mods have
worked so far.  I am not looking for you to do the work, but I wanted to
make sure I am looking at the right file.  One of my concerns with it is
that my C++ is really rusty and I haven't played with the low-level GR
stuff before, so I am muddling through what is going on in that file.  

Near the end of the file is the following:
    int to_copy = std::min((d_msg_len - d_msg_offset), noutput);
    memcpy(out, d_msg + d_msg_offset, to_copy);
I believe that that second line is where the information is put on the
output buffer.  So for a test, I changed the memcpy to be:
    memcpy(out, d_msg + d_msg_offset + 10, to_copy - 10);
to basically cut off the first 10B (just a quick and dirty test).

I then run:
    sudo make uninstall && make clean && make && sudo make install &&
sudo ldconfig
from the gr-foo/build directory.

It builds fine, but when I run my GRC script, the output to a file sink
(for simplicity I am dumping to a file instead of UDP for now), doesn't
change its length.  I did reload blocks in GRC too.