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
EXTRACT_16BITS(const void * p)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
EXTRACT_32BITS(const void * p)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
EXTRACT_64BITS(const void * p)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
EXTRACT_16BITS(const void * p)150 EXTRACT_16BITS(const void *p)
151 {
152 return ((uint16_t)ntohs(*(const uint16_t *)(p)));
153 }
154
155 static inline uint32_t
EXTRACT_32BITS(const void * p)156 EXTRACT_32BITS(const void *p)
157 {
158 return ((uint32_t)ntohl(*(const uint32_t *)(p)));
159 }
160
161 static inline uint64_t
EXTRACT_64BITS(const void * p)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