LXR linux/include/net/udplite.h

   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
  13extern struct proto             udplite_prot;
  14extern struct udp_table         udplite_table;
  15
  16/*
  17 *      Checksum computation is all in software, hence simpler getfrag.
  18 */
  19static __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 */
  26static 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 */
  35static 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
  69static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
  70{
  71        int cscov = up->len;
  72
  73        /*
  74         * Sender has set `partial coverage' option on UDP-Lite socket
  75         */
  76        if (up->pcflag & UDPLITE_SEND_CC)    {
  77                if (up->pcslen < up->len) {
  78                /* up->pcslen == 0 means that full coverage is required,
  79                 * partial coverage only if  0 < up->pcslen < up->len */
  80                        if (0 < up->pcslen) {
  81                               cscov = up->pcslen;
  82                        }
  83                        uh->len = htons(up->pcslen);
  84                }
  85        /*
  86         * NOTE: Causes for the error case  `up->pcslen > up->len':
  87         *        (i)  Application error (will not be penalized).
  88         *       (ii)  Payload too big for send buffer: data is split
  89         *             into several packets, each with its own header.
  90         *             In this case (e.g. last segment), coverage may
  91         *             exceed packet length.
  92         *       Since packets with coverage length > packet length are
  93         *       illegal, we fall back to the defaults here.
  94         */
  95        }
  96        return cscov;
  97}
  98
  99static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
 100{
 101        int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));
 102        __wsum csum = 0;
 103
 104        skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
 105
 106        skb_queue_walk(&sk->sk_write_queue, skb) {
 107                const int off = skb_transport_offset(skb);
 108                const int len = skb->len - off;
 109
 110                csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
 111
 112                if ((cscov -= len) <= 0)
 113                        break;
 114        }
 115        return csum;
 116}
 117
 118extern void     udplite4_register(void);
 119extern int      udplite_get_port(struct sock *sk, unsigned short snum,
 120                        int (*scmp)(const struct sock *, const struct sock *));
 121#endif  /* _UDPLITE_H */
 122