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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 | */ |
19 | static __inline__ int udplite_getfrag(void *from, char *to, int offset, |
20 | int len, int odd, struct sk_buff *skb) |
21 | { |
22 | return memcpy_fromiovecend(to, (struct iovec *) from, offset, len); |
23 | } |
24 | |
25 | /* Designate sk as UDP-Lite socket */ |
26 | static inline int udplite_sk_init(struct sock *sk) |
27 | { |
28 | udp_sk(sk)->pcflag = UDPLITE_BIT; |
29 | return 0; |
30 | } |
31 | |
32 | /* |
33 | * Checksumming routines |
34 | */ |
35 | static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) |
36 | { |
37 | u16 cscov; |
38 | |
39 | /* In UDPv4 a zero checksum means that the transmitter generated no |
40 | * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets |
41 | * with a zero checksum field are illegal. */ |
42 | if (uh->check == 0) { |
43 | LIMIT_NETDEBUG(KERN_DEBUG "UDPLite: zeroed checksum field\n"); |
44 | return 1; |
45 | } |
46 | |
47 | cscov = ntohs(uh->len); |
48 | |
49 | if (cscov == 0) /* Indicates that full coverage is required. */ |
50 | ; |
51 | else if (cscov < 8 || cscov > skb->len) { |
52 | /* |
53 | * Coverage length violates RFC 3828: log and discard silently. |
54 | */ |
55 | LIMIT_NETDEBUG(KERN_DEBUG "UDPLite: bad csum coverage %d/%d\n", |
56 | cscov, skb->len); |
57 | return 1; |
58 | |
59 | } else if (cscov < skb->len) { |
60 | UDP_SKB_CB(skb)->partial_cov = 1; |
61 | UDP_SKB_CB(skb)->cscov = cscov; |
62 | if (skb->ip_summed == CHECKSUM_COMPLETE) |
63 | skb->ip_summed = CHECKSUM_NONE; |
64 | } |
65 | |
66 | return 0; |
67 | } |
68 | |
69 | /* Slow-path computation of checksum. Socket is locked. */ |
70 | static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) |
71 | { |
72 | const struct udp_sock *up = udp_sk(skb->sk); |
73 | int cscov = up->len; |
74 | __wsum csum = 0; |
75 | |
76 | if (up->pcflag & UDPLITE_SEND_CC) { |
77 | /* |
78 | * Sender has set `partial coverage' option on UDP-Lite socket. |
79 | * The special case "up->pcslen == 0" signifies full coverage. |
80 | */ |
81 | if (up->pcslen < up->len) { |
82 | if (0 < up->pcslen) |
83 | cscov = up->pcslen; |
84 | udp_hdr(skb)->len = htons(up->pcslen); |
85 | } |
86 | /* |
87 | * NOTE: Causes for the error case `up->pcslen > up->len': |
88 | * (i) Application error (will not be penalized). |
89 | * (ii) Payload too big for send buffer: data is split |
90 | * into several packets, each with its own header. |
91 | * In this case (e.g. last segment), coverage may |
92 | * exceed packet length. |
93 | * Since packets with coverage length > packet length are |
94 | * illegal, we fall back to the defaults here. |
95 | */ |
96 | } |
97 | |
98 | skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ |
99 | |
100 | skb_queue_walk(&sk->sk_write_queue, skb) { |
101 | const int off = skb_transport_offset(skb); |
102 | const int len = skb->len - off; |
103 | |
104 | csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); |
105 | |
106 | if ((cscov -= len) <= 0) |
107 | break; |
108 | } |
109 | return csum; |
110 | } |
111 | |
112 | /* Fast-path computation of checksum. Socket may not be locked. */ |
113 | static inline __wsum udplite_csum(struct sk_buff *skb) |
114 | { |
115 | const struct udp_sock *up = udp_sk(skb->sk); |
116 | const int off = skb_transport_offset(skb); |
117 | int len = skb->len - off; |
118 | |
119 | if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { |
120 | if (0 < up->pcslen) |
121 | len = up->pcslen; |
122 | udp_hdr(skb)->len = htons(up->pcslen); |
123 | } |
124 | skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ |
125 | |
126 | return skb_checksum(skb, off, len, 0); |
127 | } |
128 | |
129 | void udplite4_register(void); |
130 | int udplite_get_port(struct sock *sk, unsigned short snum, |
131 | int (*scmp)(const struct sock *, const struct sock *)); |
132 | #endif /* _UDPLITE_H */ |
133 |
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