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Gerrit Renkerba4e58e2006-11-27 11:10:57 -08001/*
2 * Definitions for the UDP-Lite (RFC 3828) code.
3 */
4#ifndef _UDPLITE_H
5#define _UDPLITE_H
6
David S. Miller6bb100b2006-11-15 01:09:32 -08007#include <net/ip6_checksum.h>
8
Gerrit Renkerba4e58e2006-11-27 11:10:57 -08009/* UDP-Lite socket options */
10#define UDPLITE_SEND_CSCOV 10 /* sender partial coverage (as sent) */
11#define UDPLITE_RECV_CSCOV 11 /* receiver partial coverage (threshold ) */
12
13extern struct proto udplite_prot;
14extern struct hlist_head udplite_hash[UDP_HTABLE_SIZE];
15
16/* UDP-Lite does not have a standardized MIB yet, so we inherit from UDP */
17DECLARE_SNMP_STAT(struct udp_mib, udplite_statistics);
18
19/*
20 * Checksum computation is all in software, hence simpler getfrag.
21 */
22static __inline__ int udplite_getfrag(void *from, char *to, int offset,
23 int len, int odd, struct sk_buff *skb)
24{
25 return memcpy_fromiovecend(to, (struct iovec *) from, offset, len);
26}
27
28/* Designate sk as UDP-Lite socket */
29static inline int udplite_sk_init(struct sock *sk)
30{
31 udp_sk(sk)->pcflag = UDPLITE_BIT;
32 return 0;
33}
34
35/*
36 * Checksumming routines
37 */
38static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
39{
40 u16 cscov;
41
42 /* In UDPv4 a zero checksum means that the transmitter generated no
43 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
44 * with a zero checksum field are illegal. */
45 if (uh->check == 0) {
46 LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: zeroed checksum field\n");
47 return 1;
48 }
49
Gerrit Renkerba4e58e2006-11-27 11:10:57 -080050 cscov = ntohs(uh->len);
51
52 if (cscov == 0) /* Indicates that full coverage is required. */
Herbert Xu759e5d02007-03-25 20:10:56 -070053 ;
Gerrit Renkerba4e58e2006-11-27 11:10:57 -080054 else if (cscov < 8 || cscov > skb->len) {
55 /*
56 * Coverage length violates RFC 3828: log and discard silently.
57 */
58 LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: bad csum coverage %d/%d\n",
59 cscov, skb->len);
60 return 1;
61
Herbert Xu759e5d02007-03-25 20:10:56 -070062 } else if (cscov < skb->len) {
Gerrit Renkerba4e58e2006-11-27 11:10:57 -080063 UDP_SKB_CB(skb)->partial_cov = 1;
Herbert Xu759e5d02007-03-25 20:10:56 -070064 UDP_SKB_CB(skb)->cscov = cscov;
65 if (skb->ip_summed == CHECKSUM_COMPLETE)
66 skb->ip_summed = CHECKSUM_NONE;
67 }
Gerrit Renkerba4e58e2006-11-27 11:10:57 -080068
69 return 0;
70}
71
Gerrit Renkerba4e58e2006-11-27 11:10:57 -080072static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
73{
74 int cscov = up->len;
75
76 /*
77 * Sender has set `partial coverage' option on UDP-Lite socket
78 */
79 if (up->pcflag & UDPLITE_SEND_CC) {
80 if (up->pcslen < up->len) {
81 /* up->pcslen == 0 means that full coverage is required,
82 * partial coverage only if 0 < up->pcslen < up->len */
83 if (0 < up->pcslen) {
84 cscov = up->pcslen;
85 }
86 uh->len = htons(up->pcslen);
87 }
88 /*
89 * NOTE: Causes for the error case `up->pcslen > up->len':
90 * (i) Application error (will not be penalized).
91 * (ii) Payload too big for send buffer: data is split
92 * into several packets, each with its own header.
93 * In this case (e.g. last segment), coverage may
94 * exceed packet length.
95 * Since packets with coverage length > packet length are
96 * illegal, we fall back to the defaults here.
97 */
98 }
99 return cscov;
100}
101
Al Viro868c86b2006-11-14 21:35:48 -0800102static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
Gerrit Renkerba4e58e2006-11-27 11:10:57 -0800103{
Arnaldo Carvalho de Melo4bedb452007-03-13 14:28:48 -0300104 int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));
Al Viro868c86b2006-11-14 21:35:48 -0800105 __wsum csum = 0;
Gerrit Renkerba4e58e2006-11-27 11:10:57 -0800106
107 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
108
109 skb_queue_walk(&sk->sk_write_queue, skb) {
Arnaldo Carvalho de Meloea2ae172007-04-25 17:55:53 -0700110 const int off = skb_transport_offset(skb);
111 const int len = skb->len - off;
Gerrit Renkerba4e58e2006-11-27 11:10:57 -0800112
113 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
114
115 if ((cscov -= len) <= 0)
116 break;
117 }
118 return csum;
119}
120
121extern void udplite4_register(void);
122extern int udplite_get_port(struct sock *sk, unsigned short snum,
David S. Millerdf2bc452007-06-05 15:18:43 -0700123 int (*scmp)(const struct sock *, const struct sock *));
Gerrit Renkerba4e58e2006-11-27 11:10:57 -0800124#endif /* _UDPLITE_H */