udpiphdr
struct udpiphdr *ui;
M_PREPEND(m, sizeof(struct udpiphdr), M_DONTWAIT);
if (len + sizeof(struct udpiphdr) > IP_MAXPACKET) {
ui = mtod(m, struct udpiphdr *);
((struct ip *)ui)->ip_len = htons(sizeof(struct udpiphdr) + len);
CTASSERT(sizeof(struct udpiphdr) == 28);
ui = (struct udpiphdr *)ip;
struct udpiphdr *ui;
struct udpiphdr * ui, *oui;
ui = (struct udpiphdr *)outip;
oui = (struct udpiphdr *)&tip;