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 struct msghdr *msg = from; 23 /* XXX: stripping const */ 24 return memcpy_fromiovecend(to, (struct iovec *)msg->msg_iter.iov, offset, len); 25 } 26 27 /* Designate sk as UDP-Lite socket */ 28 static inline int udplite_sk_init(struct sock *sk) 29 { 30 udp_sk(sk)->pcflag = UDPLITE_BIT; 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 net_dbg_ratelimited("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 net_dbg_ratelimited("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 /* Slow-path computation of checksum. Socket is locked. */ 72 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) 73 { 74 const struct udp_sock *up = udp_sk(skb->sk); 75 int cscov = up->len; 76 __wsum csum = 0; 77 78 if (up->pcflag & UDPLITE_SEND_CC) { 79 /* 80 * Sender has set `partial coverage' option on UDP-Lite socket. 81 * The special case "up->pcslen == 0" signifies full coverage. 82 */ 83 if (up->pcslen < up->len) { 84 if (0 < up->pcslen) 85 cscov = up->pcslen; 86 udp_hdr(skb)->len = htons(up->pcslen); 87 } 88 /* 89 * NOTE: Causes for the error case `up->pcslen > up->len': 90 * (i) Application error (will not be penalized). 91 * (ii) Payload too big for send buffer: data is split 92 * into several packets, each with its own header. 93 * In this case (e.g. last segment), coverage may 94 * exceed packet length. 95 * Since packets with coverage length > packet length are 96 * illegal, we fall back to the defaults here. 97 */ 98 } 99 100 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 101 102 skb_queue_walk(&sk->sk_write_queue, skb) { 103 const int off = skb_transport_offset(skb); 104 const int len = skb->len - off; 105 106 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); 107 108 if ((cscov -= len) <= 0) 109 break; 110 } 111 return csum; 112 } 113 114 /* Fast-path computation of checksum. Socket may not be locked. */ 115 static inline __wsum udplite_csum(struct sk_buff *skb) 116 { 117 const struct udp_sock *up = udp_sk(skb->sk); 118 const int off = skb_transport_offset(skb); 119 int len = skb->len - off; 120 121 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 122 if (0 < up->pcslen) 123 len = up->pcslen; 124 udp_hdr(skb)->len = htons(up->pcslen); 125 } 126 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 127 128 return skb_checksum(skb, off, len, 0); 129 } 130 131 void udplite4_register(void); 132 int udplite_get_port(struct sock *sk, unsigned short snum, 133 int (*scmp)(const struct sock *, const struct sock *)); 134 #endif /* _UDPLITE_H */ 135