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 #include <pcap/compiler-tests.h> 28 29 /* 30 * Macros to extract possibly-unaligned big-endian integral values. 31 */ 32 #ifdef LBL_ALIGN 33 /* 34 * The processor doesn't natively handle unaligned loads. 35 */ 36 #if PCAP_IS_AT_LEAST_GNUC_VERSION(2,0) && \ 37 (defined(__alpha) || defined(__alpha__) || \ 38 defined(__mips) || defined(__mips__)) 39 /* 40 * This is MIPS or Alpha, which don't natively handle unaligned loads, 41 * but which have instructions that can help when doing unaligned 42 * loads, and this is GCC 2.0 or later or a compiler that claims to 43 * be GCC 2.0 or later, which we assume that mean we have 44 * __attribute__((packed)), which we can use to convince the compiler 45 * to generate those instructions. 46 * 47 * Declare packed structures containing a uint16_t and a uint32_t, 48 * cast the pointer to point to one of those, and fetch through it; 49 * the GCC manual doesn't appear to explicitly say that 50 * __attribute__((packed)) causes the compiler to generate unaligned-safe 51 * code, but it apppears to do so. 52 * 53 * We do this in case the compiler can generate code using those 54 * instructions to do an unaligned load and pass stuff to "ntohs()" or 55 * "ntohl()", which might be better than than the code to fetch the 56 * bytes one at a time and assemble them. (That might not be the 57 * case on a little-endian platform, such as DEC's MIPS machines and 58 * Alpha machines, where "ntohs()" and "ntohl()" might not be done 59 * inline.) 60 * 61 * We do this only for specific architectures because, for example, 62 * at least some versions of GCC, when compiling for 64-bit SPARC, 63 * generate code that assumes alignment if we do this. 64 * 65 * XXX - add other architectures and compilers as possible and 66 * appropriate. 67 * 68 * HP's C compiler, indicated by __HP_cc being defined, supports 69 * "#pragma unaligned N" in version A.05.50 and later, where "N" 70 * specifies a number of bytes at which the typedef on the next 71 * line is aligned, e.g. 72 * 73 * #pragma unalign 1 74 * typedef uint16_t unaligned_uint16_t; 75 * 76 * to define unaligned_uint16_t as a 16-bit unaligned data type. 77 * This could be presumably used, in sufficiently recent versions of 78 * the compiler, with macros similar to those below. This would be 79 * useful only if that compiler could generate better code for PA-RISC 80 * or Itanium than would be generated by a bunch of shifts-and-ORs. 81 * 82 * DEC C, indicated by __DECC being defined, has, at least on Alpha, 83 * an __unaligned qualifier that can be applied to pointers to get the 84 * compiler to generate code that does unaligned loads and stores when 85 * dereferencing the pointer in question. 86 * 87 * XXX - what if the native C compiler doesn't support 88 * __attribute__((packed))? How can we get it to generate unaligned 89 * accesses for *specific* items? 90 */ 91 typedef struct { 92 uint16_t val; 93 } __attribute__((packed)) unaligned_uint16_t; 94 95 typedef struct { 96 uint32_t val; 97 } __attribute__((packed)) unaligned_uint32_t; 98 99 static inline uint16_t 100 EXTRACT_16BITS(const void *p) 101 { 102 return ((uint16_t)ntohs(((const unaligned_uint16_t *)(p))->val)); 103 } 104 105 static inline uint32_t 106 EXTRACT_32BITS(const void *p) 107 { 108 return ((uint32_t)ntohl(((const unaligned_uint32_t *)(p))->val)); 109 } 110 111 static inline uint64_t 112 EXTRACT_64BITS(const void *p) 113 { 114 return ((uint64_t)(((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 0)->val)) << 32 | \ 115 ((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 1)->val)) << 0)); 116 } 117 118 #else /* have to do it a byte at a time */ 119 /* 120 * This isn't a GCC-compatible compiler, we don't have __attribute__, 121 * or we do but we don't know of any better way with this instruction 122 * set to do unaligned loads, so do unaligned loads of big-endian 123 * quantities the hard way - fetch the bytes one at a time and 124 * assemble them. 125 */ 126 #define EXTRACT_16BITS(p) \ 127 ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 0)) << 8) | \ 128 ((uint16_t)(*((const uint8_t *)(p) + 1)) << 0))) 129 #define EXTRACT_32BITS(p) \ 130 ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 24) | \ 131 ((uint32_t)(*((const uint8_t *)(p) + 1)) << 16) | \ 132 ((uint32_t)(*((const uint8_t *)(p) + 2)) << 8) | \ 133 ((uint32_t)(*((const uint8_t *)(p) + 3)) << 0))) 134 #define EXTRACT_64BITS(p) \ 135 ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 56) | \ 136 ((uint64_t)(*((const uint8_t *)(p) + 1)) << 48) | \ 137 ((uint64_t)(*((const uint8_t *)(p) + 2)) << 40) | \ 138 ((uint64_t)(*((const uint8_t *)(p) + 3)) << 32) | \ 139 ((uint64_t)(*((const uint8_t *)(p) + 4)) << 24) | \ 140 ((uint64_t)(*((const uint8_t *)(p) + 5)) << 16) | \ 141 ((uint64_t)(*((const uint8_t *)(p) + 6)) << 8) | \ 142 ((uint64_t)(*((const uint8_t *)(p) + 7)) << 0))) 143 #endif /* must special-case unaligned accesses */ 144 #else /* LBL_ALIGN */ 145 /* 146 * The processor natively handles unaligned loads, so we can just 147 * cast the pointer and fetch through it. 148 */ 149 static inline uint16_t 150 EXTRACT_16BITS(const void *p) 151 { 152 return ((uint16_t)ntohs(*(const uint16_t *)(p))); 153 } 154 155 static inline uint32_t 156 EXTRACT_32BITS(const void *p) 157 { 158 return ((uint32_t)ntohl(*(const uint32_t *)(p))); 159 } 160 161 static inline uint64_t 162 EXTRACT_64BITS(const void *p) 163 { 164 return ((uint64_t)(((uint64_t)ntohl(*((const uint32_t *)(p) + 0))) << 32 | \ 165 ((uint64_t)ntohl(*((const uint32_t *)(p) + 1))) << 0)); 166 167 } 168 169 #endif /* LBL_ALIGN */ 170 171 #define EXTRACT_24BITS(p) \ 172 ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 16) | \ 173 ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ 174 ((uint32_t)(*((const uint8_t *)(p) + 2)) << 0))) 175 176 #define EXTRACT_40BITS(p) \ 177 ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 32) | \ 178 ((uint64_t)(*((const uint8_t *)(p) + 1)) << 24) | \ 179 ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \ 180 ((uint64_t)(*((const uint8_t *)(p) + 3)) << 8) | \ 181 ((uint64_t)(*((const uint8_t *)(p) + 4)) << 0))) 182 183 #define EXTRACT_48BITS(p) \ 184 ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 40) | \ 185 ((uint64_t)(*((const uint8_t *)(p) + 1)) << 32) | \ 186 ((uint64_t)(*((const uint8_t *)(p) + 2)) << 24) | \ 187 ((uint64_t)(*((const uint8_t *)(p) + 3)) << 16) | \ 188 ((uint64_t)(*((const uint8_t *)(p) + 4)) << 8) | \ 189 ((uint64_t)(*((const uint8_t *)(p) + 5)) << 0))) 190 191 #define EXTRACT_56BITS(p) \ 192 ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 48) | \ 193 ((uint64_t)(*((const uint8_t *)(p) + 1)) << 40) | \ 194 ((uint64_t)(*((const uint8_t *)(p) + 2)) << 32) | \ 195 ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \ 196 ((uint64_t)(*((const uint8_t *)(p) + 4)) << 16) | \ 197 ((uint64_t)(*((const uint8_t *)(p) + 5)) << 8) | \ 198 ((uint64_t)(*((const uint8_t *)(p) + 6)) << 0))) 199 200 /* 201 * Macros to extract possibly-unaligned little-endian integral values. 202 * XXX - do loads on little-endian machines that support unaligned loads? 203 */ 204 #define EXTRACT_LE_8BITS(p) (*(p)) 205 #define EXTRACT_LE_16BITS(p) \ 206 ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 1)) << 8) | \ 207 ((uint16_t)(*((const uint8_t *)(p) + 0)) << 0))) 208 #define EXTRACT_LE_32BITS(p) \ 209 ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 3)) << 24) | \ 210 ((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \ 211 ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ 212 ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0))) 213 #define EXTRACT_LE_24BITS(p) \ 214 ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \ 215 ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ 216 ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0))) 217 #define EXTRACT_LE_64BITS(p) \ 218 ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 7)) << 56) | \ 219 ((uint64_t)(*((const uint8_t *)(p) + 6)) << 48) | \ 220 ((uint64_t)(*((const uint8_t *)(p) + 5)) << 40) | \ 221 ((uint64_t)(*((const uint8_t *)(p) + 4)) << 32) | \ 222 ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \ 223 ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \ 224 ((uint64_t)(*((const uint8_t *)(p) + 1)) << 8) | \ 225 ((uint64_t)(*((const uint8_t *)(p) + 0)) << 0))) 226