135 lines
3.8 KiB
C
135 lines
3.8 KiB
C
/*
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* Definitions for the UDP-Lite (RFC 3828) code.
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*/
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#ifndef _UDPLITE_H
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#define _UDPLITE_H
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#include <net/ip6_checksum.h>
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/* UDP-Lite socket options */
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#define UDPLITE_SEND_CSCOV 10 /* sender partial coverage (as sent) */
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#define UDPLITE_RECV_CSCOV 11 /* receiver partial coverage (threshold ) */
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extern struct proto udplite_prot;
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extern struct udp_table udplite_table;
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/*
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* Checksum computation is all in software, hence simpler getfrag.
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*/
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static __inline__ int udplite_getfrag(void *from, char *to, int offset,
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int len, int odd, struct sk_buff *skb)
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{
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struct msghdr *msg = from;
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/* XXX: stripping const */
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return memcpy_fromiovecend(to, (struct iovec *)msg->msg_iter.iov, offset, len);
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}
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/* Designate sk as UDP-Lite socket */
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static inline int udplite_sk_init(struct sock *sk)
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{
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udp_sk(sk)->pcflag = UDPLITE_BIT;
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return 0;
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}
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/*
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* Checksumming routines
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*/
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static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
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{
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u16 cscov;
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/* In UDPv4 a zero checksum means that the transmitter generated no
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* checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
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* with a zero checksum field are illegal. */
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if (uh->check == 0) {
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net_dbg_ratelimited("UDPLite: zeroed checksum field\n");
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return 1;
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}
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cscov = ntohs(uh->len);
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if (cscov == 0) /* Indicates that full coverage is required. */
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;
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else if (cscov < 8 || cscov > skb->len) {
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/*
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* Coverage length violates RFC 3828: log and discard silently.
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*/
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net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",
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cscov, skb->len);
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return 1;
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} else if (cscov < skb->len) {
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UDP_SKB_CB(skb)->partial_cov = 1;
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UDP_SKB_CB(skb)->cscov = cscov;
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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skb->ip_summed = CHECKSUM_NONE;
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}
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return 0;
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}
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/* Slow-path computation of checksum. Socket is locked. */
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static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
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{
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const struct udp_sock *up = udp_sk(skb->sk);
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int cscov = up->len;
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__wsum csum = 0;
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if (up->pcflag & UDPLITE_SEND_CC) {
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/*
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* Sender has set `partial coverage' option on UDP-Lite socket.
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* The special case "up->pcslen == 0" signifies full coverage.
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*/
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if (up->pcslen < up->len) {
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if (0 < up->pcslen)
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cscov = up->pcslen;
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udp_hdr(skb)->len = htons(up->pcslen);
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}
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/*
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* NOTE: Causes for the error case `up->pcslen > up->len':
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* (i) Application error (will not be penalized).
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* (ii) Payload too big for send buffer: data is split
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* into several packets, each with its own header.
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* In this case (e.g. last segment), coverage may
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* exceed packet length.
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* Since packets with coverage length > packet length are
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* illegal, we fall back to the defaults here.
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*/
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}
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skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
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skb_queue_walk(&sk->sk_write_queue, skb) {
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const int off = skb_transport_offset(skb);
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const int len = skb->len - off;
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csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
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if ((cscov -= len) <= 0)
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break;
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}
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return csum;
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}
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/* Fast-path computation of checksum. Socket may not be locked. */
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static inline __wsum udplite_csum(struct sk_buff *skb)
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{
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const struct udp_sock *up = udp_sk(skb->sk);
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const int off = skb_transport_offset(skb);
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int len = skb->len - off;
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if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
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if (0 < up->pcslen)
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len = up->pcslen;
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udp_hdr(skb)->len = htons(up->pcslen);
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}
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skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
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return skb_checksum(skb, off, len, 0);
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}
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void udplite4_register(void);
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int udplite_get_port(struct sock *sk, unsigned short snum,
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int (*scmp)(const struct sock *, const struct sock *));
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#endif /* _UDPLITE_H */
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