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 /* UDP-Lite does not have a standardized MIB yet, so we inherit from UDP */
  17 DECLARE_SNMP_STAT(struct udp_mib, udplite_statistics);
  18
  19 /*
  20  *      Checksum computation is all in software, hence simpler getfrag.
  21  */
  22 static __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 */
  29 static 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  */
  38 static 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         UDP_SKB_CB(skb)->partial_cov = 0;
  51         cscov = ntohs(uh->len);
  52
  53         if (cscov == 0)          /* Indicates that full coverage is required. */
  54                 cscov = skb->len;
  55         else if (cscov < 8  || cscov > skb->len) {
  56                 /*
  57                  * Coverage length violates RFC 3828: log and discard silently.
  58                  */
  59                 LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: bad csum coverage %d/%d\n",
  60                                cscov, skb->len);
  61                 return 1;
  62
  63         } else if (cscov < skb->len)
  64                 UDP_SKB_CB(skb)->partial_cov = 1;
  65
  66         UDP_SKB_CB(skb)->cscov = cscov;
  67
  68         /*
  69          * There is no known NIC manufacturer supporting UDP-Lite yet,
  70          * hence ip_summed is always (re-)set to CHECKSUM_NONE.
  71          */
  72         skb->ip_summed = CHECKSUM_NONE;
  73
  74         return 0;
  75 }
  76
  77 static __inline__ int udplite4_csum_init(struct sk_buff *skb, struct udphdr *uh)
  78 {
  79         int rc = udplite_checksum_init(skb, uh);
  80
  81         if (!rc)
  82                 skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr,
  83                                                skb->nh.iph->daddr,
  84                                                skb->len, IPPROTO_UDPLITE, 0);
  85         return rc;
  86 }
  87
  88 static __inline__ int udplite6_csum_init(struct sk_buff *skb, struct udphdr *uh)
  89 {
  90         int rc = udplite_checksum_init(skb, uh);
  91
  92         if (!rc)
  93                 skb->csum = ~csum_unfold(csum_ipv6_magic(&skb->nh.ipv6h->saddr,
  94                                              &skb->nh.ipv6h->daddr,
  95                                              skb->len, IPPROTO_UDPLITE, 0));
  96         return rc;
  97 }
  98
  99 static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
 100 {
 101         int cscov = up->len;
 102
 103         /*
 104          * Sender has set `partial coverage' option on UDP-Lite socket
 105          */
 106         if (up->pcflag & UDPLITE_SEND_CC)    {
 107                 if (up->pcslen < up->len) {
 108                 /* up->pcslen == 0 means that full coverage is required,
 109                  * partial coverage only if  0 < up->pcslen < up->len */
 110                         if (0 < up->pcslen) {
 111                                cscov = up->pcslen;
 112                         }
 113                         uh->len = htons(up->pcslen);
 114                 }
 115         /*
 116          * NOTE: Causes for the error case  `up->pcslen > up->len':
 117          *        (i)  Application error (will not be penalized).
 118          *       (ii)  Payload too big for send buffer: data is split
 119          *             into several packets, each with its own header.
 120          *             In this case (e.g. last segment), coverage may
 121          *             exceed packet length.
 122          *       Since packets with coverage length > packet length are
 123          *       illegal, we fall back to the defaults here.
 124          */
 125         }
 126         return cscov;
 127 }
 128
 129 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
 130 {
 131         int off, len, cscov = udplite_sender_cscov(udp_sk(sk), skb->h.uh);
 132         __wsum csum = 0;
 133
 134         skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
 135
 136         skb_queue_walk(&sk->sk_write_queue, skb) {
 137                 off = skb->h.raw - skb->data;
 138                 len = skb->len - off;
 139
 140                 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
 141
 142                 if ((cscov -= len) <= 0)
 143                         break;
 144         }
 145         return csum;
 146 }
 147
 148 extern void     udplite4_register(void);
 149 extern int      udplite_get_port(struct sock *sk, unsigned short snum,
 150                         int (*scmp)(const struct sock *, const struct sock *));
 151 #endif  /* _UDPLITE_H */