C / Python WinPCap Translation

Sorry, this will be a very simple question for most of you.

I'm trying to convert some of the code from here into Python (3.4) as I don't know C. That's primarily the basis of this issue. While I have created the Python data structures according to the link:

from ctypes import *
u_short = c_ushort
u_char = c_ubyte
u_int = c_int

class ip_address(Structure):
    _fields=[("byte1",u_char),
             ("byte2",u_char),
             ("byte3",u_char),
             ("byte4",u_char)]

class ip_header(Structure):
    _fields=[("ver_ihl",u_char),
             ("tos",u_char),
             ("tlen",u_short),
             ("identification",u_short),
             ("flags_fo",u_short),
             ("ttl",u_char),
             ("proto",u_char),
             ("crc",u_short),
             ("saddr",ip_address),
             ("daddr",ip_address),
             ("op_pad",u_int)]

class udp_header(Structure):
    _fields=[("sport",u_short),
             ("dport",u_short),
             ("len",u_short),
             ("crc",u_short)]

class data(Structure):
    _fields[("data",c_char_p)]

I don't know enough about C to convert the following code in Python:

ip_header *ih;
udp_header *uh;
u_int ip_len;
u_short sport,dport;

/* retrieve the position of the ip header */
ih = (ip_header *) (pkt_data +
    14); //length of ethernet header

/* retrieve the position of the udp header */
ip_len = (ih->ver_ihl & 0xf) * 4;
uh = (udp_header *) ((u_char*)ih + ip_len);

/* convert from network byte order to host byte order */
sport = ntohs( uh->sport );
dport = ntohs( uh->dport );

/* print ip addresses and udp ports */
printf("%d.%d.%d.%d.%d -> %d.%d.%d.%d.%d\n",
    ih->saddr.byte1,
    ih->saddr.byte2,
    ih->saddr.byte3,
    ih->saddr.byte4,
    sport,
    ih->daddr.byte1,
    ih->daddr.byte2,
    ih->daddr.byte3,
    ih->daddr.byte4,
    dport);

I know that I need to change the "ih->ver_ihl" to "ih.ver_ihl" however I don't understand the rest. If I understand UDP packets correctly, the next section of the packet will be Data. I would also like to extract that from the packet if possible.

Thanks in advance for any help you can provide