UDP checksum calculation

Question

The UDP header struct defined at /usr/include/netinet/udp.h is as follows

struct udphdr
{
  u_int16_t source;
  u_int16_t dest;
  u_int16_t len;
  u_int16_t          


        

Answer 1

I was searching the net for some code which will calculate the udp header (with the pseudo ip header as mentioned above).

Finally I found the open-bsd dhclient packet.c:

https://github.com/openbsd/src/blob/master/sbin/dhclient/packet.c

check out the function assemble_udp_ip_header()