/* *	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 udp_table		udplite_table; /* *	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;} /* Slow-path computation of checksum. Socket is locked. */static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb){	const struct udp_sock *up = udp_sk(skb->sk);	int cscov = up->len;	__wsum csum = 0; 	if (up->pcflag & UDPLITE_SEND_CC) {		/*		 * Sender has set `partial coverage' option on UDP-Lite socket.		 * The special case "up->pcslen == 0" signifies full coverage.		 */		if (up->pcslen < up->len) {			if (0 < up->pcslen)				cscov = up->pcslen;			udp_hdr(skb)->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.		 */	} 	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;} /* Fast-path computation of checksum. Socket may not be locked. */static inline __wsum udplite_csum(struct sk_buff *skb){	const struct udp_sock *up = udp_sk(skb->sk);	const int off = skb_transport_offset(skb);	int len = skb->len - off; 	if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {		if (0 < up->pcslen)			len = up->pcslen;		udp_hdr(skb)->len = htons(up->pcslen);	}	skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */ 	return skb_checksum(skb, off, len, 0);} 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 */