Sending binary data over sockets with Python

Question

I\'m looking to script some basic requests over the SPDY protocol. The protocol defines the frames you send as being comprised of binary data of very specific length and byt

Answer 1

You can also use the struct module to define the header format with a string and parse it directly.

To generate a packet:

fmt = 'B I 4b'
your_binary_data = pack(fmt, header_data)
sock.sendall(your_binary_data)

Where fmt indicates the header format ('B I 4b' is just a, clearly not working for your SPDY header, example). Unfortunately, you will have to deal with non-byte-alligned header fields, probably by parsing bigger chunks and then dividing them according to your format.

Aside that, to parse the header:

unpacker = struct.Struct('B I 4b')
unpacked_data = unpacker.unpack(s.recv(unpacker.size))

unpacked_data will contain a tuple with the parsed data.

The struct module performs conversions between Python values and C structs represented as Python strings. I have no guarantees about the efficiency of this approach, but it helped me to parse different protocols just by adjusting the fmt string.