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31 /* $KAME: sctp_crc32.c,v 1.12 2005/03/06 16:04:17 itojun Exp $ */
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include <sys/types.h>
38 #include <sys/socket.h>
39 #include <sys/socketvar.h>
41 #include <sys/libkern.h>
42 #include <netinet/sctp.h>
43 #include <netinet/sctp_os.h>
44 #include <netinet/sctp_crc32.h>
45 #include <netinet/sctp_pcb.h>
48 #if !defined(SCTP_WITH_NO_CSUM)
51 sctp_finalize_crc32c(uint32_t crc32c)
55 #if BYTE_ORDER == BIG_ENDIAN
56 uint8_t byte0, byte1, byte2, byte3;
59 /* Complement the result */
61 #if BYTE_ORDER == BIG_ENDIAN
63 * For BIG-ENDIAN.. aka Motorola byte order the result is in
64 * little-endian form. So we must manually swap the bytes. Then we
65 * can call htonl() which does nothing...
67 byte0 = result & 0x000000ff;
68 byte1 = (result >> 8) & 0x000000ff;
69 byte2 = (result >> 16) & 0x000000ff;
70 byte3 = (result >> 24) & 0x000000ff;
71 crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
74 * For INTEL platforms the result comes out in network order. No
75 * htonl is required or the swap above. So we optimize out both the
76 * htonl and the manual swap above.
84 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
87 * given a mbuf chain with a packetheader offset by 'offset'
88 * pointing at a sctphdr (with csum set to 0) go through the chain
89 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also
90 * has a side bonus as it will calculate the total length of the
91 * mbuf chain. Note: if offset is greater than the total mbuf
92 * length, checksum=1, pktlen=0 is returned (ie. no real error code)
94 uint32_t base = 0xffffffff;
98 /* find the correct mbuf and offset into mbuf */
99 while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) {
100 offset -= SCTP_BUF_LEN(at); /* update remaining offset
102 at = SCTP_BUF_NEXT(at);
105 if ((SCTP_BUF_LEN(at) - offset) > 0) {
106 base = calculate_crc32c(base,
107 (unsigned char *)(SCTP_BUF_AT(at, offset)),
108 (unsigned int)(SCTP_BUF_LEN(at) - offset));
111 /* we only offset once into the first mbuf */
112 if (offset < (uint32_t) SCTP_BUF_LEN(at))
115 offset -= SCTP_BUF_LEN(at);
117 at = SCTP_BUF_NEXT(at);
119 base = sctp_finalize_crc32c(base);
126 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
131 #endif /* !defined(SCTP_WITH_NO_CSUM) */
135 sctp_delayed_cksum(struct mbuf *m)
141 ip = mtod(m, struct ip *);
142 offset = ip->ip_hl << 2;
143 checksum = sctp_calculate_cksum(m, offset);
144 SCTP_STAT_DECR(sctps_sendhwcrc);
145 SCTP_STAT_INCR(sctps_sendswcrc);
146 offset += offsetof(struct sctphdr, checksum);
148 if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) {
149 printf("delayed m_pullup, m->len: %d off: %d p: %d\n",
150 (uint32_t) m->m_len, offset, ip->ip_p);
152 * XXX this shouldn't happen, but if it does, the correct
153 * behavior may be to insert the checksum in the appropriate
154 * next mbuf in the chain.
158 *(uint32_t *) (m->m_data + offset) = checksum;