aboutsummaryrefslogtreecommitdiff
path: root/include/net/udplite.h
blob: 81bdbf97319b216ad1d7955aa13c7cae2c8ac044 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/* SPDX-License-Identifier: GPL-2.0 */
/*
 *	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)
{
	struct msghdr *msg = from;
	return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;
}

/* Designate sk as UDP-Lite socket */
static inline int udplite_sk_init(struct sock *sk)
{
	udp_init_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) {
		net_dbg_ratelimited("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.
		 */
		net_dbg_ratelimited("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);
}

void udplite4_register(void);
int udplite_get_port(struct sock *sk, unsigned short snum,
		     int (*scmp)(const struct sock *, const struct sock *));
#endif	/* _UDPLITE_H */