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