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1 /*
2 * libopenemv - a library to work with EMV family of smart cards
3 * Copyright (C) 2015 Dmitry Eremin-Solenikov
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 */
15
16 #ifdef HAVE_CONFIG_H
17 #include <config.h>
18 #endif
19
20 #include "emv/dol.h"
21 #include "emv/tlv.h"
22
23 #include <stdlib.h>
24 #include <string.h>
25
26 static size_t dol_calculate_len(const struct tlv *tlv, size_t data_len)
27 {
28 if (!tlv)
29 return 0;
30
31 const unsigned char *buf = tlv->value;
32 size_t left = tlv->len;
33 size_t count = 0;
34
35 while (left) {
36 struct tlv tlv;
37 if (!tlv_parse_tl(&buf, &left, &tlv))
38 return 0;
39
40 count += tlv.len;
41
42 /* Last tag can be of variable length */
43 if (tlv.len == 0 && left == 0)
44 count = data_len;
45 }
46
47 return count;
48 }
49
50 struct tlv *dol_process(const struct tlv *tlv, const struct tlvdb *tlvdb, tlv_tag_t tag)
51 {
52 size_t res_len;
53 if (!tlv || !(res_len = dol_calculate_len(tlv, 0))) {
54 struct tlv *res_tlv = malloc(sizeof(*res_tlv));
55
56 res_tlv->tag = tag;
57 res_tlv->len = 0;
58 res_tlv->value = NULL;
59
60 return res_tlv;
61 }
62
63 struct tlv *res_tlv = malloc(sizeof(*res_tlv) + res_len);
64 if (!res_tlv)
65 return NULL;
66
67 const unsigned char *buf = tlv->value;
68 size_t left = tlv->len;
69 unsigned char *res = (unsigned char *)(res_tlv + 1);
70 size_t pos = 0;
71
72 while (left) {
73 struct tlv cur_tlv;
74 if (!tlv_parse_tl(&buf, &left, &cur_tlv) || pos + cur_tlv.len > res_len) {
75 free(res_tlv);
76
77 return NULL;
78 }
79
80 const struct tlv *tag_tlv = tlvdb_get(tlvdb, cur_tlv.tag, NULL);
81 if (!tag_tlv) {
82 memset(res + pos, 0, cur_tlv.len);
83 } else if (tag_tlv->len > cur_tlv.len) {
84 memcpy(res + pos, tag_tlv->value, cur_tlv.len);
85 } else {
86 // FIXME: cn data should be padded with 0xFF !!!
87 memcpy(res + pos, tag_tlv->value, tag_tlv->len);
88 memset(res + pos + tag_tlv->len, 0, cur_tlv.len - tag_tlv->len);
89 }
90 pos += cur_tlv.len;
91 }
92
93 res_tlv->tag = tag;
94 res_tlv->len = res_len;
95 res_tlv->value = res;
96
97 return res_tlv;
98 }
99
100 struct tlvdb *dol_parse(const struct tlv *tlv, const unsigned char *data, size_t data_len)
101 {
102 if (!tlv)
103 return NULL;
104
105 const unsigned char *buf = tlv->value;
106 size_t left = tlv->len;
107 size_t res_len = dol_calculate_len(tlv, data_len);
108 size_t pos = 0;
109 struct tlvdb *db = NULL;
110
111 if (res_len != data_len)
112 return NULL;
113
114 while (left) {
115 struct tlv cur_tlv;
116 if (!tlv_parse_tl(&buf, &left, &cur_tlv) || pos + cur_tlv.len > res_len) {
117 tlvdb_free(db);
118 return NULL;
119 }
120
121 /* Last tag can be of variable length */
122 if (cur_tlv.len == 0 && left == 0)
123 cur_tlv.len = res_len - pos;
124
125 struct tlvdb *tag_db = tlvdb_fixed(cur_tlv.tag, cur_tlv.len, data + pos);
126 if (!db)
127 db = tag_db;
128 else
129 tlvdb_add(db, tag_db);
130
131 pos += cur_tlv.len;
132 }
133
134 return db;
135 }
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