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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_crc32.h>
44 #include <netinet/sctp_pcb.h>
47 #if !defined(SCTP_WITH_NO_CSUM)
50 sctp_finalize_crc32c(uint32_t crc32c)
54 #if BYTE_ORDER == BIG_ENDIAN
55 uint8_t byte0, byte1, byte2, byte3;
58 /* Complement the result */
60 #if BYTE_ORDER == BIG_ENDIAN
62 * For BIG-ENDIAN.. aka Motorola byte order the result is in
63 * little-endian form. So we must manually swap the bytes. Then we
64 * can call htonl() which does nothing...
66 byte0 = result & 0x000000ff;
67 byte1 = (result >> 8) & 0x000000ff;
68 byte2 = (result >> 16) & 0x000000ff;
69 byte3 = (result >> 24) & 0x000000ff;
70 crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
73 * For INTEL platforms the result comes out in network order. No
74 * htonl is required or the swap above. So we optimize out both the
75 * htonl and the manual swap above.
83 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
86 * given a mbuf chain with a packetheader offset by 'offset'
87 * pointing at a sctphdr (with csum set to 0) go through the chain
88 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also
89 * has a side bonus as it will calculate the total length of the
90 * mbuf chain. Note: if offset is greater than the total mbuf
91 * length, checksum=1, pktlen=0 is returned (ie. no real error code)
93 uint32_t base = 0xffffffff;
97 /* find the correct mbuf and offset into mbuf */
98 while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) {
99 offset -= SCTP_BUF_LEN(at); /* update remaining offset
101 at = SCTP_BUF_NEXT(at);
104 if ((SCTP_BUF_LEN(at) - offset) > 0) {
105 base = calculate_crc32c(base,
106 (unsigned char *)(SCTP_BUF_AT(at, offset)),
107 (unsigned int)(SCTP_BUF_LEN(at) - offset));
110 /* we only offset once into the first mbuf */
111 if (offset < (uint32_t) SCTP_BUF_LEN(at))
114 offset -= SCTP_BUF_LEN(at);
116 at = SCTP_BUF_NEXT(at);
118 base = sctp_finalize_crc32c(base);
125 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
130 #endif /* !defined(SCTP_WITH_NO_CSUM) */
134 sctp_delayed_cksum(struct mbuf *m)
140 ip = mtod(m, struct ip *);
141 offset = ip->ip_hl << 2;
142 checksum = sctp_calculate_cksum(m, offset);
143 SCTP_STAT_DECR(sctps_sendhwcrc);
144 SCTP_STAT_INCR(sctps_sendswcrc);
145 offset += offsetof(struct sctphdr, checksum);
147 if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) {
148 printf("delayed m_pullup, m->len: %d off: %d p: %d\n",
149 (uint32_t) m->m_len, offset, ip->ip_p);
151 * XXX this shouldn't happen, but if it does, the correct
152 * behavior may be to insert the checksum in the appropriate
153 * next mbuf in the chain.
157 *(uint32_t *) (m->m_data + offset) = checksum;