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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 <netinet/sctp_os.h>
38 #include <netinet/sctp.h>
39 #include <netinet/sctp_crc32.h>
40 #include <netinet/sctp_pcb.h>
43 #if !defined(SCTP_WITH_NO_CSUM)
46 sctp_finalize_crc32c(uint32_t crc32c)
50 #if BYTE_ORDER == BIG_ENDIAN
51 uint8_t byte0, byte1, byte2, byte3;
54 /* Complement the result */
56 #if BYTE_ORDER == BIG_ENDIAN
58 * For BIG-ENDIAN.. aka Motorola byte order the result is in
59 * little-endian form. So we must manually swap the bytes. Then we
60 * can call htonl() which does nothing...
62 byte0 = result & 0x000000ff;
63 byte1 = (result >> 8) & 0x000000ff;
64 byte2 = (result >> 16) & 0x000000ff;
65 byte3 = (result >> 24) & 0x000000ff;
66 crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
69 * For INTEL platforms the result comes out in network order. No
70 * htonl is required or the swap above. So we optimize out both the
71 * htonl and the manual swap above.
79 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
82 * given a mbuf chain with a packetheader offset by 'offset'
83 * pointing at a sctphdr (with csum set to 0) go through the chain
84 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also
85 * has a side bonus as it will calculate the total length of the
86 * mbuf chain. Note: if offset is greater than the total mbuf
87 * length, checksum=1, pktlen=0 is returned (ie. no real error code)
89 uint32_t base = 0xffffffff;
93 /* find the correct mbuf and offset into mbuf */
94 while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) {
95 offset -= SCTP_BUF_LEN(at); /* update remaining offset
97 at = SCTP_BUF_NEXT(at);
100 if ((SCTP_BUF_LEN(at) - offset) > 0) {
101 base = calculate_crc32c(base,
102 (unsigned char *)(SCTP_BUF_AT(at, offset)),
103 (unsigned int)(SCTP_BUF_LEN(at) - offset));
106 /* we only offset once into the first mbuf */
107 if (offset < (uint32_t) SCTP_BUF_LEN(at))
110 offset -= SCTP_BUF_LEN(at);
112 at = SCTP_BUF_NEXT(at);
114 base = sctp_finalize_crc32c(base);
121 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
126 #endif /* !defined(SCTP_WITH_NO_CSUM) */
130 sctp_delayed_cksum(struct mbuf *m)
136 ip = mtod(m, struct ip *);
137 offset = ip->ip_hl << 2;
138 checksum = sctp_calculate_cksum(m, offset);
139 SCTP_STAT_DECR(sctps_sendhwcrc);
140 SCTP_STAT_INCR(sctps_sendswcrc);
141 offset += offsetof(struct sctphdr, checksum);
143 if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) {
144 printf("delayed m_pullup, m->len: %d off: %d p: %d\n",
145 (uint32_t) m->m_len, offset, ip->ip_p);
147 * XXX this shouldn't happen, but if it does, the correct
148 * behavior may be to insert the checksum in the appropriate
149 * next mbuf in the chain.
153 *(uint32_t *) (m->m_data + offset) = checksum;