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 #ifdef CONFIG_IP_UDPLITE 29 udp_sk(sk)->pcflag = UDPLITE_BIT; 30 #endif 31 return 0; 32 } 33 34 /* 35 * Checksumming routines 36 */ 37 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 38 { 39 u16 cscov; 40 41 /* In UDPv4 a zero checksum means that the transmitter generated no 42 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets 43 * with a zero checksum field are illegal. */ 44 if (uh->check == 0) { 45 LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: zeroed checksum field\n"); 46 return 1; 47 } 48 49 cscov = ntohs(uh->len); 50 51 if (cscov == 0) /* Indicates that full coverage is required. */ 52 ; 53 else if (cscov < 8 || cscov > skb->len) { 54 /* 55 * Coverage length violates RFC 3828: log and discard silently. 56 */ 57 LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: bad csum coverage %d/%d\n", 58 cscov, skb->len); 59 return 1; 60 61 } else if (cscov < skb->len) { 62 UDP_SKB_CB(skb)->partial_cov = 1; 63 UDP_SKB_CB(skb)->cscov = cscov; 64 if (skb->ip_summed == CHECKSUM_COMPLETE) 65 skb->ip_summed = CHECKSUM_NONE; 66 } 67 68 return 0; 69 } 70 71 static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh) 72 { 73 int cscov = up->len; 74 #ifdef CONFIG_IP_UDPLITE 75 /* 76 * Sender has set `partial coverage' option on UDP-Lite socket 77 */ 78 if (up->pcflag & UDPLITE_SEND_CC) { 79 if (up->pcslen < up->len) { 80 /* up->pcslen == 0 means that full coverage is required, 81 * partial coverage only if 0 < up->pcslen < up->len */ 82 if (0 < up->pcslen) { 83 cscov = up->pcslen; 84 } 85 uh->len = htons(up->pcslen); 86 } 87 /* 88 * NOTE: Causes for the error case `up->pcslen > up->len': 89 * (i) Application error (will not be penalized). 90 * (ii) Payload too big for send buffer: data is split 91 * into several packets, each with its own header. 92 * In this case (e.g. last segment), coverage may 93 * exceed packet length. 94 * Since packets with coverage length > packet length are 95 * illegal, we fall back to the defaults here. 96 */ 97 } 98 #endif 99 return cscov; 100 } 101 102 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) 103 { 104 __wsum csum = 0; 105 #ifdef CONFIG_IP_UDPLITE 106 int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb)); 107 108 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 109 110 skb_queue_walk(&sk->sk_write_queue, skb) { 111 const int off = skb_transport_offset(skb); 112 const int len = skb->len - off; 113 114 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); 115 116 if ((cscov -= len) <= 0) 117 break; 118 } 119 #endif 120 return csum; 121 } 122 123 extern void udplite4_register(void); 124 extern int udplite_get_port(struct sock *sk, unsigned short snum, 125 int (*scmp)(const struct sock *, const struct sock *)); 126 #endif /* _UDPLITE_H */ 127