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Diffstat (limited to 'contrib/tcpdump/extract.h')
| -rw-r--r-- | contrib/tcpdump/extract.h | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/contrib/tcpdump/extract.h b/contrib/tcpdump/extract.h new file mode 100644 index 0000000..bab63f2 --- /dev/null +++ b/contrib/tcpdump/extract.h @@ -0,0 +1,130 @@ +/* + * Copyright (c) 1992, 1993, 1994, 1995, 1996 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that: (1) source code distributions + * retain the above copyright notice and this paragraph in its entirety, (2) + * distributions including binary code include the above copyright notice and + * this paragraph in its entirety in the documentation or other materials + * provided with the distribution, and (3) all advertising materials mentioning + * features or use of this software display the following acknowledgement: + * ``This product includes software developed by the University of California, + * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of + * the University nor the names of its contributors may be used to endorse + * or promote products derived from this software without specific prior + * written permission. + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + * + * @(#) $Header: /tcpdump/master/tcpdump/extract.h,v 1.25 2006-01-30 16:20:07 hannes Exp $ (LBL) + */ + +/* + * Macros to extract possibly-unaligned big-endian integral values. + */ +#ifdef LBL_ALIGN +/* + * The processor doesn't natively handle unaligned loads. + */ +#ifdef HAVE___ATTRIBUTE__ +/* + * We have __attribute__; we assume that means we have __attribute__((packed)). + * Declare packed structures containing a u_int16_t and a u_int32_t, + * cast the pointer to point to one of those, and fetch through it; + * the GCC manual doesn't appear to explicitly say that + * __attribute__((packed)) causes the compiler to generate unaligned-safe + * code, but it apppears to do so. + * + * We do this in case the compiler can generate, for this instruction set, + * better code to do an unaligned load and pass stuff to "ntohs()" or + * "ntohl()" than the code to fetch the bytes one at a time and + * assemble them. (That might not be the case on a little-endian platform, + * where "ntohs()" and "ntohl()" might not be done inline.) + */ +typedef struct { + u_int16_t val; +} __attribute__((packed)) unaligned_u_int16_t; + +typedef struct { + u_int32_t val; +} __attribute__((packed)) unaligned_u_int32_t; + +#define EXTRACT_16BITS(p) \ + ((u_int16_t)ntohs(((const unaligned_u_int16_t *)(p))->val)) +#define EXTRACT_32BITS(p) \ + ((u_int32_t)ntohl(((const unaligned_u_int32_t *)(p))->val)) +#define EXTRACT_64BITS(p) \ + ((u_int64_t)(((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p) + 0)->val)) << 32 | \ + ((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p) + 1)->val)) << 0)) + +#else /* HAVE___ATTRIBUTE__ */ +/* + * We don't have __attribute__, so do unaligned loads of big-endian + * quantities the hard way - fetch the bytes one at a time and + * assemble them. + */ +#define EXTRACT_16BITS(p) \ + ((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 0) << 8 | \ + (u_int16_t)*((const u_int8_t *)(p) + 1))) +#define EXTRACT_32BITS(p) \ + ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 24 | \ + (u_int32_t)*((const u_int8_t *)(p) + 1) << 16 | \ + (u_int32_t)*((const u_int8_t *)(p) + 2) << 8 | \ + (u_int32_t)*((const u_int8_t *)(p) + 3))) +#define EXTRACT_64BITS(p) \ + ((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 0) << 56 | \ + (u_int64_t)*((const u_int8_t *)(p) + 1) << 48 | \ + (u_int64_t)*((const u_int8_t *)(p) + 2) << 40 | \ + (u_int64_t)*((const u_int8_t *)(p) + 3) << 32 | \ + (u_int64_t)*((const u_int8_t *)(p) + 4) << 24 | \ + (u_int64_t)*((const u_int8_t *)(p) + 5) << 16 | \ + (u_int64_t)*((const u_int8_t *)(p) + 6) << 8 | \ + (u_int64_t)*((const u_int8_t *)(p) + 7))) +#endif /* HAVE___ATTRIBUTE__ */ +#else /* LBL_ALIGN */ +/* + * The processor natively handles unaligned loads, so we can just + * cast the pointer and fetch through it. + */ +#define EXTRACT_16BITS(p) \ + ((u_int16_t)ntohs(*(const u_int16_t *)(p))) +#define EXTRACT_32BITS(p) \ + ((u_int32_t)ntohl(*(const u_int32_t *)(p))) +#define EXTRACT_64BITS(p) \ + ((u_int64_t)(((u_int64_t)ntohl(*((const u_int32_t *)(p) + 0))) << 32 | \ + ((u_int64_t)ntohl(*((const u_int32_t *)(p) + 1))) << 0)) +#endif /* LBL_ALIGN */ + +#define EXTRACT_24BITS(p) \ + ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 16 | \ + (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ + (u_int32_t)*((const u_int8_t *)(p) + 2))) + +/* + * Macros to extract possibly-unaligned little-endian integral values. + * XXX - do loads on little-endian machines that support unaligned loads? + */ +#define EXTRACT_LE_8BITS(p) (*(p)) +#define EXTRACT_LE_16BITS(p) \ + ((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 1) << 8 | \ + (u_int16_t)*((const u_int8_t *)(p) + 0))) +#define EXTRACT_LE_32BITS(p) \ + ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 3) << 24 | \ + (u_int32_t)*((const u_int8_t *)(p) + 2) << 16 | \ + (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ + (u_int32_t)*((const u_int8_t *)(p) + 0))) +#define EXTRACT_LE_24BITS(p) \ + ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 2) << 16 | \ + (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ + (u_int32_t)*((const u_int8_t *)(p) + 0))) +#define EXTRACT_LE_64BITS(p) \ + ((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 7) << 56 | \ + (u_int64_t)*((const u_int8_t *)(p) + 6) << 48 | \ + (u_int64_t)*((const u_int8_t *)(p) + 5) << 40 | \ + (u_int64_t)*((const u_int8_t *)(p) + 4) << 32 | \ + (u_int64_t)*((const u_int8_t *)(p) + 3) << 24 | \ + (u_int64_t)*((const u_int8_t *)(p) + 2) << 16 | \ + (u_int64_t)*((const u_int8_t *)(p) + 1) << 8 | \ + (u_int64_t)*((const u_int8_t *)(p) + 0))) |
