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 /* Slow-path computation of checksum. Socket is locked. */ 70 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) 71 { 72 const struct udp_sock *up = udp_sk(skb->sk); 73 int cscov = up->len; 74 __wsum csum = 0; 75 76 if (up->pcflag & UDPLITE_SEND_CC) { 77 /* 78 * Sender has set `partial coverage' option on UDP-Lite socket. 79 * The special case "up->pcslen == 0" signifies full coverage. 80 */ 81 if (up->pcslen < up->len) { 82 if (0 < up->pcslen) 83 cscov = up->pcslen; 84 udp_hdr(skb)->len = htons(up->pcslen); 85 } 86 /* 87 * NOTE: Causes for the error case `up->pcslen > up->len': 88 * (i) Application error (will not be penalized). 89 * (ii) Payload too big for send buffer: data is split 90 * into several packets, each with its own header. 91 * In this case (e.g. last segment), coverage may 92 * exceed packet length. 93 * Since packets with coverage length > packet length are 94 * illegal, we fall back to the defaults here. 95 */ 96 } 97 98 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 99 100 skb_queue_walk(&sk->sk_write_queue, skb) { 101 const int off = skb_transport_offset(skb); 102 const int len = skb->len - off; 103 104 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); 105 106 if ((cscov -= len) <= 0) 107 break; 108 } 109 return csum; 110 } 111 112 /* Fast-path computation of checksum. Socket may not be locked. */ 113 static inline __wsum udplite_csum(struct sk_buff *skb) 114 { 115 const struct udp_sock *up = udp_sk(skb->sk); 116 const int off = skb_transport_offset(skb); 117 int len = skb->len - off; 118 119 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 120 if (0 < up->pcslen) 121 len = up->pcslen; 122 udp_hdr(skb)->len = htons(up->pcslen); 123 } 124 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 125 126 return skb_checksum(skb, off, len, 0); 127 } 128 129 void udplite4_register(void); 130 int udplite_get_port(struct sock *sk, unsigned short snum, 131 int (*scmp)(const struct sock *, const struct sock *)); 132 #endif /* _UDPLITE_H */ 133