Question

I’m receiving a struct over a network from a C server to my Python client. The protocol is UDP. I have no control over the server and it’s protocols/data formats. It consists of this struct (yes, an IPv4 + port):

struct ip_s {
    uint8_t i1;
    uint8_t i2;
    uint8_t i3;
    uint8_t i4;
    uint16_t port; // big endian
};

Apart from the port which is converted to big-endian the data is sent “as-is”, casted to a (char*).

How can I receive this struct to a format that is processable by Python?

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Misc info:

• Python 2.7 or 3.x
• Cross-platform
• Preferably solution using only built-in modules

Answer 1

Look into struct.unpack

It will probably look something like this:

# socket setup

(buffer, sockaddress) = mysocket.recvfrom(6)
if len(buffer)== 6:
    i1,i2,i3,i4, port = struct.unpack('!BBBBH', buffer)