dns_mx_packet - extract MX records from DNS answer packet

       dns_mx_packet  is a low-level component of dns_mx, designed to support asynchronous DNS lookups. It reads
       a DNS packet of length len from buf, extracts the MX records from the answer section of the packet,  puts
       the result into out, and returns 0 or -1 the same way as dns_mx.

       dns_mx_packet - extract MX records from DNS answer packet

dns_mx(3), dns_ip4(3), dns_ip6(3)

                                                                                                dns_mx_packet(3)

#include<libowfat/dns.h>

       int dns_mx_packet(stralloc* out,const char* buf,
                         unsigned int len);