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   1 /*
   2  * Copyright (c) 1992, 1993, 1994, 1995, 1996
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 #ifndef _WIN32
  23 #include <arpa/inet.h>
  24 #endif
  25
  26 #include <pcap/pcap-inttypes.h>
  27
  28 /*
  29  * Macros to extract possibly-unaligned big-endian integral values.
  30  */
  31 #ifdef LBL_ALIGN
  32 /*
  33  * The processor doesn't natively handle unaligned loads.
  34  */
  35 #if defined(__GNUC__) && defined(HAVE___ATTRIBUTE__) && \
  36     (defined(__alpha) || defined(__alpha__) || \
  37      defined(__mips) || defined(__mips__))
  38
  39 /*
  40  * This is a GCC-compatible compiler and we have __attribute__, which
  41  * we assume that mean we have __attribute__((packed)), and this is
  42  * MIPS or Alpha, which has instructions that can help when doing
  43  * unaligned loads.
  44  *
  45  * Declare packed structures containing a uint16_t and a uint32_t,
  46  * cast the pointer to point to one of those, and fetch through it;
  47  * the GCC manual doesn't appear to explicitly say that
  48  * __attribute__((packed)) causes the compiler to generate unaligned-safe
  49  * code, but it apppears to do so.
  50  *
  51  * We do this in case the compiler can generate code using those
  52  * instructions to do an unaligned load and pass stuff to "ntohs()" or
  53  * "ntohl()", which might be better than than the code to fetch the
  54  * bytes one at a time and assemble them.  (That might not be the
  55  * case on a little-endian platform, such as DEC's MIPS machines and
  56  * Alpha machines, where "ntohs()" and "ntohl()" might not be done
  57  * inline.)
  58  *
  59  * We do this only for specific architectures because, for example,
  60  * at least some versions of GCC, when compiling for 64-bit SPARC,
  61  * generate code that assumes alignment if we do this.
  62  *
  63  * XXX - add other architectures and compilers as possible and
  64  * appropriate.
  65  *
  66  * HP's C compiler, indicated by __HP_cc being defined, supports
  67  * "#pragma unaligned N" in version A.05.50 and later, where "N"
  68  * specifies a number of bytes at which the typedef on the next
  69  * line is aligned, e.g.
  70  *
  71  *      #pragma unalign 1
  72  *      typedef uint16_t unaligned_uint16_t;
  73  *
  74  * to define unaligned_uint16_t as a 16-bit unaligned data type.
  75  * This could be presumably used, in sufficiently recent versions of
  76  * the compiler, with macros similar to those below.  This would be
  77  * useful only if that compiler could generate better code for PA-RISC
  78  * or Itanium than would be generated by a bunch of shifts-and-ORs.
  79  *
  80  * DEC C, indicated by __DECC being defined, has, at least on Alpha,
  81  * an __unaligned qualifier that can be applied to pointers to get the
  82  * compiler to generate code that does unaligned loads and stores when
  83  * dereferencing the pointer in question.
  84  *
  85  * XXX - what if the native C compiler doesn't support
  86  * __attribute__((packed))?  How can we get it to generate unaligned
  87  * accesses for *specific* items?
  88  */
  89 typedef struct {
  90         uint16_t        val;
  91 } __attribute__((packed)) unaligned_uint16_t;
  92
  93 typedef struct {
  94         uint32_t        val;
  95 } __attribute__((packed)) unaligned_uint32_t;
  96
  97 static inline uint16_t
  98 EXTRACT_16BITS(const void *p)
  99 {
 100         return ((uint16_t)ntohs(((const unaligned_uint16_t *)(p))->val));
 101 }
 102
 103 static inline uint32_t
 104 EXTRACT_32BITS(const void *p)
 105 {
 106         return ((uint32_t)ntohl(((const unaligned_uint32_t *)(p))->val));
 107 }
 108
 109 static inline uint64_t
 110 EXTRACT_64BITS(const void *p)
 111 {
 112         return ((uint64_t)(((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 0)->val)) << 32 | \
 113                 ((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 1)->val)) << 0));
 114 }
 115
 116 #else /* have to do it a byte at a time */
 117 /*
 118  * This isn't a GCC-compatible compiler, we don't have __attribute__,
 119  * or we do but we don't know of any better way with this instruction
 120  * set to do unaligned loads, so do unaligned loads of big-endian
 121  * quantities the hard way - fetch the bytes one at a time and
 122  * assemble them.
 123  */
 124 #define EXTRACT_16BITS(p) \
 125         ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 0)) << 8) | \
 126                     ((uint16_t)(*((const uint8_t *)(p) + 1)) << 0)))
 127 #define EXTRACT_32BITS(p) \
 128         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 24) | \
 129                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 16) | \
 130                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 8) | \
 131                     ((uint32_t)(*((const uint8_t *)(p) + 3)) << 0)))
 132 #define EXTRACT_64BITS(p) \
 133         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 56) | \
 134                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 48) | \
 135                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 40) | \
 136                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 32) | \
 137                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 24) | \
 138                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 16) | \
 139                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 8) | \
 140                     ((uint64_t)(*((const uint8_t *)(p) + 7)) << 0)))
 141 #endif /* must special-case unaligned accesses */
 142 #else /* LBL_ALIGN */
 143 /*
 144  * The processor natively handles unaligned loads, so we can just
 145  * cast the pointer and fetch through it.
 146  */
 147 static inline uint16_t
 148 EXTRACT_16BITS(const void *p)
 149 {
 150         return ((uint16_t)ntohs(*(const uint16_t *)(p)));
 151 }
 152
 153 static inline uint32_t
 154 EXTRACT_32BITS(const void *p)
 155 {
 156         return ((uint32_t)ntohl(*(const uint32_t *)(p)));
 157 }
 158
 159 static inline uint64_t
 160 EXTRACT_64BITS(const void *p)
 161 {
 162         return ((uint64_t)(((uint64_t)ntohl(*((const uint32_t *)(p) + 0))) << 32 | \
 163                 ((uint64_t)ntohl(*((const uint32_t *)(p) + 1))) << 0));
 164
 165 }
 166
 167 #endif /* LBL_ALIGN */
 168
 169 #define EXTRACT_24BITS(p) \
 170         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 16) | \
 171                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 172                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 0)))
 173
 174 #define EXTRACT_40BITS(p) \
 175         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 32) | \
 176                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 24) | \
 177                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 178                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 8) | \
 179                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 0)))
 180
 181 #define EXTRACT_48BITS(p) \
 182         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 40) | \
 183                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 32) | \
 184                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 24) | \
 185                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 16) | \
 186                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 8) | \
 187                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 0)))
 188
 189 #define EXTRACT_56BITS(p) \
 190         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 48) | \
 191                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 40) | \
 192                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 32) | \
 193                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 194                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 16) | \
 195                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 8) | \
 196                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 0)))
 197
 198 /*
 199  * Macros to extract possibly-unaligned little-endian integral values.
 200  * XXX - do loads on little-endian machines that support unaligned loads?
 201  */
 202 #define EXTRACT_LE_8BITS(p) (*(p))
 203 #define EXTRACT_LE_16BITS(p) \
 204         ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 205                     ((uint16_t)(*((const uint8_t *)(p) + 0)) << 0)))
 206 #define EXTRACT_LE_32BITS(p) \
 207         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 208                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 209                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 210                     ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
 211 #define EXTRACT_LE_24BITS(p) \
 212         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 213                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 214                     ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
 215 #define EXTRACT_LE_64BITS(p) \
 216         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 7)) << 56) | \
 217                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 48) | \
 218                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 40) | \
 219                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 32) | \
 220                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 221                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 222                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 223                     ((uint64_t)(*((const uint8_t *)(p) + 0)) << 0)))