mitmproxy/libmproxy/platform/linux.py

import socket, struct

# Python socket module does not have this constant
SO_ORIGINAL_DST = 80

class Resolver:
    def original_addr(self, csock):
        odestdata = csock.getsockopt(socket.SOL_IP, SO_ORIGINAL_DST, 16)
        _, port, a1, a2, a3, a4 = struct.unpack("!HHBBBBxxxxxxxx", odestdata)
        address = "%d.%d.%d.%d" % (a1, a2, a3, a4)
        return address, port