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
  13 extern struct proto             udplite_prot;
  14 extern struct hlist_head        udplite_hash[UDP_HTABLE_SIZE];
  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 static 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
  99 static 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
 118 extern void     udplite4_register(void);
 119 extern int      udplite_get_port(struct sock *sk, unsigned short snum,
 120                         int (*scmp)(const struct sock *, const struct sock *));
 121 #endif  /* _UDPLITE_H */