1 /*
2 * Definitions for the UDP-Lite (RFC 3828) code.
3 */
4 #ifndef _UDPLITE_H
5 #define _UDPLITE_H
6
7 #include <net/ip6_checksum.h>
8
9 /* 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
13 extern struct proto udplite_prot;
14 extern struct udp_table udplite_table;
15
16 /*
17 * Checksum computation is all in software, hence simpler getfrag.
18 */
udplite_getfrag(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)19 static __inline__ int udplite_getfrag(void *from, char *to, int offset,
20 int len, int odd, struct sk_buff *skb)
21 {
22 struct msghdr *msg = from;
23 return copy_from_iter(to, len, &msg->msg_iter) != len ? -EFAULT : 0;
24 }
25
26 /* Designate sk as UDP-Lite socket */
udplite_sk_init(struct sock * sk)27 static inline int udplite_sk_init(struct sock *sk)
28 {
29 udp_sk(sk)->pcflag = UDPLITE_BIT;
30 return 0;
31 }
32
33 /*
34 * Checksumming routines
35 */
udplite_checksum_init(struct sk_buff * skb,struct udphdr * uh)36 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
37 {
38 u16 cscov;
39
40 /* In UDPv4 a zero checksum means that the transmitter generated no
41 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
42 * with a zero checksum field are illegal. */
43 if (uh->check == 0) {
44 net_dbg_ratelimited("UDPLite: zeroed checksum field\n");
45 return 1;
46 }
47
48 cscov = ntohs(uh->len);
49
50 if (cscov == 0) /* Indicates that full coverage is required. */
51 ;
52 else if (cscov < 8 || cscov > skb->len) {
53 /*
54 * Coverage length violates RFC 3828: log and discard silently.
55 */
56 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",
57 cscov, skb->len);
58 return 1;
59
60 } else if (cscov < skb->len) {
61 UDP_SKB_CB(skb)->partial_cov = 1;
62 UDP_SKB_CB(skb)->cscov = cscov;
63 if (skb->ip_summed == CHECKSUM_COMPLETE)
64 skb->ip_summed = CHECKSUM_NONE;
65 skb->csum_valid = 0;
66 }
67
68 return 0;
69 }
70
71 /* Slow-path computation of checksum. Socket is locked. */
udplite_csum_outgoing(struct sock * sk,struct sk_buff * skb)72 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
73 {
74 const struct udp_sock *up = udp_sk(skb->sk);
75 int cscov = up->len;
76 __wsum csum = 0;
77
78 if (up->pcflag & UDPLITE_SEND_CC) {
79 /*
80 * Sender has set `partial coverage' option on UDP-Lite socket.
81 * The special case "up->pcslen == 0" signifies full coverage.
82 */
83 if (up->pcslen < up->len) {
84 if (0 < up->pcslen)
85 cscov = up->pcslen;
86 udp_hdr(skb)->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
100 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
101
102 skb_queue_walk(&sk->sk_write_queue, skb) {
103 const int off = skb_transport_offset(skb);
104 const int len = skb->len - off;
105
106 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
107
108 if ((cscov -= len) <= 0)
109 break;
110 }
111 return csum;
112 }
113
114 /* Fast-path computation of checksum. Socket may not be locked. */
udplite_csum(struct sk_buff * skb)115 static inline __wsum udplite_csum(struct sk_buff *skb)
116 {
117 const struct udp_sock *up = udp_sk(skb->sk);
118 const int off = skb_transport_offset(skb);
119 int len = skb->len - off;
120
121 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
122 if (0 < up->pcslen)
123 len = up->pcslen;
124 udp_hdr(skb)->len = htons(up->pcslen);
125 }
126 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
127
128 return skb_checksum(skb, off, len, 0);
129 }
130
131 void udplite4_register(void);
132 int udplite_get_port(struct sock *sk, unsigned short snum,
133 int (*scmp)(const struct sock *, const struct sock *));
134 #endif /* _UDPLITE_H */
135