2 * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
3 * Redistribution and modifications are permitted subject to BSD license.
5 #include <asn_internal.h>
6 #include <ber_tlv_length.h>
7 #include <ber_tlv_tag.h>
10 ber_fetch_length(int _is_constructed, const void *bufptr, size_t size,
11 ber_tlv_len_t *len_r) {
12 const uint8_t *buf = (const uint8_t *)bufptr;
16 return 0; /* Want more */
18 oct = *(const uint8_t *)buf;
19 if((oct & 0x80) == 0) {
21 * Short definite length.
23 *len_r = oct; /* & 0x7F */
29 if(_is_constructed && oct == 0x80) {
30 *len_r = -1; /* Indefinite length */
35 /* Reserved in standard for future use. */
39 oct &= 0x7F; /* Leave only the 7 LS bits */
40 for(len = 0, buf++, skipped = 1;
41 oct && (++skipped <= size); buf++, oct--) {
43 len = (len << 8) | *buf;
45 || (len >> ((8 * sizeof(len)) - 8) && oct > 1)) {
47 * Too large length value.
54 ber_tlv_len_t lenplusepsilon = (size_t)len + 1024;
56 * Here length may be very close or equal to 2G.
57 * However, the arithmetics used in some decoders
58 * may add some (small) quantities to the length,
59 * to check the resulting value against some limits.
60 * This may result in integer wrap-around, which
61 * we try to avoid by checking it earlier here.
63 if(lenplusepsilon < 0) {
64 /* Too large length value */
72 return 0; /* Want more */
78 ber_skip_length(asn_codec_ctx_t *opt_codec_ctx,
79 int _is_constructed, const void *ptr, size_t size) {
80 ber_tlv_len_t vlen; /* Length of V in TLV */
81 ssize_t ll; /* Length of L in TLV */
85 * Make sure we didn't exceed the maximum stack size.
87 if(_ASN_STACK_OVERFLOW_CHECK(opt_codec_ctx))
91 * Determine the size of L in TLV.
93 ll = ber_fetch_length(_is_constructed, ptr, size, &vlen);
94 if(ll <= 0) return ll;
102 return 0; /* Want more */
109 ASN_DEBUG("Skipping indefinite length");
110 for(skip = ll, ptr = ((const char *)ptr) + ll, size -= ll;;) {
114 ssize_t tl = ber_fetch_tag(ptr, size, &tag);
115 if(tl <= 0) return tl;
117 ll = ber_skip_length(opt_codec_ctx,
118 BER_TLV_CONSTRUCTED(ptr),
119 ((const char *)ptr) + tl, size - tl);
120 if(ll <= 0) return ll;
125 * This may be the end of the indefinite length structure,
126 * two consecutive 0 octets.
127 * Check if it is true.
129 if(((const uint8_t *)ptr)[0] == 0
130 && ((const uint8_t *)ptr)[1] == 0)
133 ptr = ((const char *)ptr) + tl + ll;
141 der_tlv_length_serialize(ber_tlv_len_t len, void *bufp, size_t size) {
142 size_t required_size; /* Size of len encoding */
143 uint8_t *buf = (uint8_t *)bufp;
148 /* Encoded in 1 octet */
149 if(size) *buf = (uint8_t)len;
154 * Compute the size of the subsequent bytes.
156 for(required_size = 1, i = 8; i < 8 * sizeof(len); i += 8) {
163 if(size <= required_size)
164 return required_size + 1;
166 *buf++ = (uint8_t)(0x80 | required_size); /* Length of the encoding */
169 * Produce the len encoding, space permitting.
171 end = buf + required_size;
172 for(i -= 8; buf < end; i -= 8, buf++)
173 *buf = (uint8_t)(len >> i);
175 return required_size + 1;