#include "all.h" #include "../ip/ip.h" voidudprecv(Msgbuf *mb, Ifc *ifc){	Udppkt *uh;	int udplen, plen; 	uh = (Udppkt*)mb->data; 	plen = mb->count;	if(plen < Ensize+Ipsize+Udpsize)		goto drop; 	udplen = nhgets(uh->udplen);	if(udplen+Ensize+Ipsize > plen)		goto drop; 	/* construct pseudo hdr and check sum */	uh->ttl = 0;	hnputs(uh->cksum, udplen);	if(nhgets(uh->udpsum)	  && ptclcsum((uchar*)uh+(Ensize+Ipsize-Udpphsize), udplen + Udpphsize) != 0) {		if(ifc->sumerr < 3)			print("udp: cksum error %I\n", uh->src);		ifc->sumerr++;		goto drop;	} 	switch(nhgets(uh->udpdst)) {	case 520:		riprecv(mb, ifc);		break;	case SNTP_LOCAL:		sntprecv(mb, ifc);		break;	default:		mbfree(mb);		break;	}	return; drop:	mbfree(mb);}