/* *	Definitions for the UDP-Lite (RFC 3828) code. */#ifndef _UDPLITE_H#define _UDPLITE_H#include <net/ip6_checksum.h>/* UDP-Lite socket options */#define UDPLITE_SEND_CSCOV   10 /* sender partial coverage (as sent)      */#define UDPLITE_RECV_CSCOV   11 /* receiver partial coverage (threshold ) */extern struct proto 		udplite_prot;extern struct hlist_head 	udplite_hash[UDP_HTABLE_SIZE];/* UDP-Lite does not have a standardized MIB yet, so we inherit from UDP */DECLARE_SNMP_STAT(struct udp_mib, udplite_statistics);/* *	Checksum computation is all in software, hence simpler getfrag. */static __inline__ int udplite_getfrag(void *from, char *to, int  offset,				      int len, int odd, struct sk_buff *skb){	return memcpy_fromiovecend(to, (struct iovec *) from, offset, len);}/* Designate sk as UDP-Lite socket */static inline int udplite_sk_init(struct sock *sk){	udp_sk(sk)->pcflag = UDPLITE_BIT;	return 0;}/* * 	Checksumming routines */static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh){	u16 cscov;        /* In UDPv4 a zero checksum means that the transmitter generated no         * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets         * with a zero checksum field are illegal.                            */	if (uh->check == 0) {		LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: zeroed checksum field\n");		return 1;	}	cscov = ntohs(uh->len);	if (cscov == 0)		 /* Indicates that full coverage is required. */		;	else if (cscov < 8  || cscov > skb->len) {		/*		 * Coverage length violates RFC 3828: log and discard silently.		 */		LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: bad csum coverage %d/%d\n",			       cscov, skb->len);		return 1;	} else if (cscov < skb->len) {        	UDP_SKB_CB(skb)->partial_cov = 1;		UDP_SKB_CB(skb)->cscov = cscov;		if (skb->ip_summed == CHECKSUM_COMPLETE)			skb->ip_summed = CHECKSUM_NONE;        }	return 0;}static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh){	int cscov = up->len;	/*	 * Sender has set `partial coverage' option on UDP-Lite socket	 */	if (up->pcflag & UDPLITE_SEND_CC)    {		if (up->pcslen < up->len) {		/* up->pcslen == 0 means that full coverage is required,		 * partial coverage only if  0 < up->pcslen < up->len */			if (0 < up->pcslen) {			       cscov = up->pcslen;			}			uh->len = htons(up->pcslen);		}	/*	 * NOTE: Causes for the error case  `up->pcslen > up->len':	 *        (i)  Application error (will not be penalized).	 *       (ii)  Payload too big for send buffer: data is split	 *             into several packets, each with its own header.	 *             In this case (e.g. last segment), coverage may	 *             exceed packet length.	 *       Since packets with coverage length > packet length are	 *       illegal, we fall back to the defaults here.	 */	}	return cscov;}static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb){	int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));	__wsum csum = 0;	skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */	skb_queue_walk(&sk->sk_write_queue, skb) {		const int off = skb_transport_offset(skb);		const int len = skb->len - off;		csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);		if ((cscov -= len) <= 0)			break;	}	return csum;}extern void	udplite4_register(void);extern int 	udplite_get_port(struct sock *sk, unsigned short snum,			int (*scmp)(const struct sock *, const struct sock *));#endif	/* _UDPLITE_H */