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 return copy_from_iter(to, len, &msg->msg_iter) != len ? -EFAULT : 0; 24 } 25 26 /* Designate sk as UDP-Lite socket */ 27 static inline int udplite_sk_init(struct sock *sk) 28 { 29 udp_sk(sk)->pcflag = UDPLITE_BIT; 30 return 0; 31 } 32 33 /* 34 * Checksumming routines 35 */ 36 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 37 { 38 u16 cscov; 39 40 /* In UDPv4 a zero checksum means that the transmitter generated no 41 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets 42 * with a zero checksum field are illegal. */ 43 if (uh->check == 0) { 44 net_dbg_ratelimited("UDPLite: zeroed checksum field\n"); 45 return 1; 46 } 47 48 cscov = ntohs(uh->len); 49 50 if (cscov == 0) /* Indicates that full coverage is required. */ 51 ; 52 else if (cscov < 8 || cscov > skb->len) { 53 /* 54 * Coverage length violates RFC 3828: log and discard silently. 55 */ 56 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n", 57 cscov, skb->len); 58 return 1; 59 60 } else if (cscov < skb->len) { 61 UDP_SKB_CB(skb)->partial_cov = 1; 62 UDP_SKB_CB(skb)->cscov = cscov; 63 if (skb->ip_summed == CHECKSUM_COMPLETE) 64 skb->ip_summed = CHECKSUM_NONE; 65 } 66 67 return 0; 68 } 69 70 /* Slow-path computation of checksum. Socket is locked. */ 71 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) 72 { 73 const struct udp_sock *up = udp_sk(skb->sk); 74 int cscov = up->len; 75 __wsum csum = 0; 76 77 if (up->pcflag & UDPLITE_SEND_CC) { 78 /* 79 * Sender has set `partial coverage' option on UDP-Lite socket. 80 * The special case "up->pcslen == 0" signifies full coverage. 81 */ 82 if (up->pcslen < up->len) { 83 if (0 < up->pcslen) 84 cscov = up->pcslen; 85 udp_hdr(skb)->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 99 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 100 101 skb_queue_walk(&sk->sk_write_queue, skb) { 102 const int off = skb_transport_offset(skb); 103 const int len = skb->len - off; 104 105 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); 106 107 if ((cscov -= len) <= 0) 108 break; 109 } 110 return csum; 111 } 112 113 /* Fast-path computation of checksum. Socket may not be locked. */ 114 static inline __wsum udplite_csum(struct sk_buff *skb) 115 { 116 const struct udp_sock *up = udp_sk(skb->sk); 117 const int off = skb_transport_offset(skb); 118 int len = skb->len - off; 119 120 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 121 if (0 < up->pcslen) 122 len = up->pcslen; 123 udp_hdr(skb)->len = htons(up->pcslen); 124 } 125 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 126 127 return skb_checksum(skb, off, len, 0); 128 } 129 130 void udplite4_register(void); 131 int udplite_get_port(struct sock *sk, unsigned short snum, 132 int (*scmp)(const struct sock *, const struct sock *)); 133 #endif /* _UDPLITE_H */ 134