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gerrit.osmocom.org / libasn1c / 424132003433e8587d1919e94860ae3247a7df41 / . / src / per_decoder.c
blob: 20fe1a1dbd188ecb4d40c404816c62b79ca591ef [file] [log] [blame]
Harald Welte92c45f32010-06-12 18:59:38 +0200[diff] [blame]1#include <asn_application.h>
2#include <asn_internal.h>
3#include <per_decoder.h>
4
Harald Welteec0e2172010-07-20 00:03:44 +0200[diff] [blame]5/*
6 * Decode a "Production of a complete encoding", X.691#10.1.
7 * The complete encoding contains at least one byte, and is an integral
8 * multiple of 8 bytes.
9 */
10asn_dec_rval_t
11uper_decode_complete(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td, void **sptr, const void *buffer, size_t size) {
12 asn_dec_rval_t rval;
13
14 rval = uper_decode(opt_codec_ctx, td, sptr, buffer, size, 0, 0);
15 if(rval.consumed) {
16 /*
17 * We've always given 8-aligned data,
18 * so convert bits to integral bytes.
19 */
20 rval.consumed += 7;
21 rval.consumed >>= 3;
22 } else if(rval.code == RC_OK) {
23 if(size) {
Harald Welte41b85d52015-08-31 08:56:53 +0200[diff] [blame]24 if(((const uint8_t *)buffer)[0] == 0) {
25 rval.consumed = 1; /* 1 byte */
26 } else {
27 ASN_DEBUG("Expecting single zeroed byte");
28 rval.code = RC_FAIL;
29 }
30 } else {
31 /* Must contain at least 8 bits. */
32 rval.code = RC_WMORE;
33 }
34 }
35
36 return rval;
37}
38
39asn_dec_rval_t
40aper_decode_complete(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td, void **sptr, const void *buffer, size_t size) {
41 asn_dec_rval_t rval;
42
43 rval = aper_decode(opt_codec_ctx, td, sptr, buffer, size, 0, 0);
44 if(rval.consumed) {
45 /*
46 * We've always given 8-aligned data,
47 * so convert bits to integral bytes.
48 */
49 rval.consumed += 7;
50 rval.consumed >>= 3;
51 } else if(rval.code == RC_OK) {
52 if(size) {
Harald Welteec0e2172010-07-20 00:03:44 +0200[diff] [blame]53 if(((uint8_t *)buffer)[0] == 0) {
54 rval.consumed = 1; /* 1 byte */
55 } else {
56 ASN_DEBUG("Expecting single zeroed byte");
57 rval.code = RC_FAIL;
58 }
59 } else {
60 /* Must contain at least 8 bits. */
61 rval.code = RC_WMORE;
62 }
63 }
64
65 return rval;
66}
67
Harald Welte92c45f32010-06-12 18:59:38 +0200[diff] [blame]68asn_dec_rval_t
69uper_decode(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td, void **sptr, const void *buffer, size_t size, int skip_bits, int unused_bits) {
70 asn_codec_ctx_t s_codec_ctx;
71 asn_dec_rval_t rval;
72 asn_per_data_t pd;
73
74 if(skip_bits < 0 || skip_bits > 7
75 || unused_bits < 0 || unused_bits > 7
76 || (unused_bits > 0 && !size))
77 _ASN_DECODE_FAILED;
78
79 /*
80 * Stack checker requires that the codec context
81 * must be allocated on the stack.
82 */
83 if(opt_codec_ctx) {
84 if(opt_codec_ctx->max_stack_size) {
85 s_codec_ctx = *opt_codec_ctx;
86 opt_codec_ctx = &s_codec_ctx;
87 }
88 } else {
89 /* If context is not given, be security-conscious anyway */
90 memset(&s_codec_ctx, 0, sizeof(s_codec_ctx));
91 s_codec_ctx.max_stack_size = _ASN_DEFAULT_STACK_MAX;
92 opt_codec_ctx = &s_codec_ctx;
93 }
94
95 /* Fill in the position indicator */
Harald Welteec0e2172010-07-20 00:03:44 +0200[diff] [blame]96 memset(&pd, 0, sizeof(pd));
Harald Welte92c45f32010-06-12 18:59:38 +0200[diff] [blame]97 pd.buffer = (const uint8_t *)buffer;
98 pd.nboff = skip_bits;
99 pd.nbits = 8 * size - unused_bits; /* 8 is CHAR_BIT from <limits.h> */
100 if(pd.nboff > pd.nbits)
101 _ASN_DECODE_FAILED;
102
103 /*
104 * Invoke type-specific decoder.
105 */
106 if(!td->uper_decoder)
107 _ASN_DECODE_FAILED; /* PER is not compiled in */
108 rval = td->uper_decoder(opt_codec_ctx, td, 0, sptr, &pd);
109 if(rval.code == RC_OK) {
110 /* Return the number of consumed bits */
111 rval.consumed = ((pd.buffer - (const uint8_t *)buffer) << 3)
112 + pd.nboff - skip_bits;
Harald Welte41b85d52015-08-31 08:56:53 +0200[diff] [blame]113 ASN_DEBUG("PER decoding consumed %ld, counted %ld",
114 (long)rval.consumed, (long)pd.moved);
Harald Welteec0e2172010-07-20 00:03:44 +0200[diff] [blame]115 assert(rval.consumed == pd.moved);
Harald Welte92c45f32010-06-12 18:59:38 +0200[diff] [blame]116 } else {
117 /* PER codec is not a restartable */
118 rval.consumed = 0;
119 }
120 return rval;
121}
122
Harald Welte41b85d52015-08-31 08:56:53 +0200[diff] [blame]123asn_dec_rval_t
124aper_decode(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td, void **sptr, const void *buffer, size_t size, int skip_bits, int unused_bits) {
125 asn_codec_ctx_t s_codec_ctx;
126 asn_dec_rval_t rval;
127 asn_per_data_t pd;
128
129 if(skip_bits < 0 || skip_bits > 7
130 || unused_bits < 0 || unused_bits > 7
131 || (unused_bits > 0 && !size))
132 _ASN_DECODE_FAILED;
133
134 /*
135 * Stack checker requires that the codec context
136 * must be allocated on the stack.
137 */
138 if(opt_codec_ctx) {
139 if(opt_codec_ctx->max_stack_size) {
140 s_codec_ctx = *opt_codec_ctx;
141 opt_codec_ctx = &s_codec_ctx;
142 }
143 } else {
144 /* If context is not given, be security-conscious anyway */
145 memset(&s_codec_ctx, 0, sizeof(s_codec_ctx));
146 s_codec_ctx.max_stack_size = _ASN_DEFAULT_STACK_MAX;
147 opt_codec_ctx = &s_codec_ctx;
148 }
149
150 /* Fill in the position indicator */
151 memset(&pd, 0, sizeof(pd));
152 pd.buffer = (const uint8_t *)buffer;
153 pd.nboff = skip_bits;
154 pd.nbits = 8 * size - unused_bits; /* 8 is CHAR_BIT from <limits.h> */
155 if(pd.nboff > pd.nbits)
156 _ASN_DECODE_FAILED;
157
158 /*
159 * Invoke type-specific decoder.
160 */
161 if(!td->aper_decoder)
162 _ASN_DECODE_FAILED; /* PER is not compiled in */
163 rval = td->aper_decoder(opt_codec_ctx, td, 0, sptr, &pd);
164 if(rval.code == RC_OK) {
165 /* Return the number of consumed bits */
166 rval.consumed = ((pd.buffer - (const uint8_t *)buffer) << 3)
167 + pd.nboff - skip_bits;
168 ASN_DEBUG("PER decoding consumed %d, counted %d",
169 rval.consumed, pd.moved);
170 assert(rval.consumed == pd.moved);
171 } else {
172 /* PER codec is not a restartable */
173 rval.consumed = 0;
174 }
175 return rval;
176}