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 udp_table udplite_table; 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 */ 122