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 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
  50        cscov = ntohs(uh->len);
  51
  52        if (cscov == 0)          /* Indicates that full coverage is required. */
  53                ;
  54        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
  62        } else if (cscov < skb->len) {
  63                UDP_SKB_CB(skb)->partial_cov = 1;
  64                UDP_SKB_CB(skb)->cscov = cscov;
  65                if (skb->ip_summed == CHECKSUM_COMPLETE)
  66                        skb->ip_summed = CHECKSUM_NONE;
  67        }
  68
  69        return 0;
  70}
  71
  72static 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
 102static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
 103{
 104        int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));
 105        __wsum csum = 0;
 106
 107        skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
 108
 109        skb_queue_walk(&sk->sk_write_queue, skb) {
 110                const int off = skb_transport_offset(skb);
 111                const int len = skb->len - off;
 112
 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,
 123                        int (*scmp)(const struct sock *, const struct sock *));
 124#endif  /* _UDPLITE_H */
 125