1/*
2 * Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <stdio.h>
11#include "internal/cryptlib.h"
12#include <openssl/asn1t.h>
13
14#if !(OPENSSL_API_COMPAT < 0x10200000L)
15NON_EMPTY_TRANSLATION_UNIT
16#else
17
18#define COPY_SIZE(a, b) (sizeof(a) < sizeof(b) ? sizeof(a) : sizeof(b))
19
20/*
21 * Custom primitive type for long handling. This converts between an
22 * ASN1_INTEGER and a long directly.
23 */
24
25static int long_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
26static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
27
28static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
29                    const ASN1_ITEM *it);
30static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
31                    int utype, char *free_cont, const ASN1_ITEM *it);
32static int long_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
33                      int indent, const ASN1_PCTX *pctx);
34
35static ASN1_PRIMITIVE_FUNCS long_pf = {
36    NULL, 0,
37    long_new,
38    long_free,
39    long_free,                  /* Clear should set to initial value */
40    long_c2i,
41    long_i2c,
42    long_print
43};
44
45ASN1_ITEM_start(LONG)
46        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, ASN1_LONG_UNDEF, "LONG"
47ASN1_ITEM_end(LONG)
48
49ASN1_ITEM_start(ZLONG)
50        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, 0, "ZLONG"
51ASN1_ITEM_end(ZLONG)
52
53static int long_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
54{
55    memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));
56    return 1;
57}
58
59static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
60{
61    memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));
62}
63
64/*
65 * Originally BN_num_bits_word was called to perform this operation, but
66 * trouble is that there is no guarantee that sizeof(long) equals to
67 * sizeof(BN_ULONG). BN_ULONG is a configurable type that can be as wide
68 * as long, but also double or half...
69 */
70static int num_bits_ulong(unsigned long value)
71{
72    size_t i;
73    unsigned long ret = 0;
74
75    /*
76     * It is argued that *on average* constant counter loop performs
77     * not worse [if not better] than one with conditional break or
78     * mask-n-table-lookup-style, because of branch misprediction
79     * penalties.
80     */
81    for (i = 0; i < sizeof(value) * 8; i++) {
82        ret += (value != 0);
83        value >>= 1;
84    }
85
86    return (int)ret;
87}
88
89static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
90                    const ASN1_ITEM *it)
91{
92    long ltmp;
93    unsigned long utmp, sign;
94    int clen, pad, i;
95
96    memcpy(&ltmp, pval, COPY_SIZE(*pval, ltmp));
97    if (ltmp == it->size)
98        return -1;
99    /*
100     * Convert the long to positive: we subtract one if negative so we can
101     * cleanly handle the padding if only the MSB of the leading octet is
102     * set.
103     */
104    if (ltmp < 0) {
105        sign = 0xff;
106        utmp = 0 - (unsigned long)ltmp - 1;
107    } else {
108        sign = 0;
109        utmp = ltmp;
110    }
111    clen = num_bits_ulong(utmp);
112    /* If MSB of leading octet set we need to pad */
113    if (!(clen & 0x7))
114        pad = 1;
115    else
116        pad = 0;
117
118    /* Convert number of bits to number of octets */
119    clen = (clen + 7) >> 3;
120
121    if (cont != NULL) {
122        if (pad)
123            *cont++ = (unsigned char)sign;
124        for (i = clen - 1; i >= 0; i--) {
125            cont[i] = (unsigned char)(utmp ^ sign);
126            utmp >>= 8;
127        }
128    }
129    return clen + pad;
130}
131
132static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
133                    int utype, char *free_cont, const ASN1_ITEM *it)
134{
135    int i;
136    long ltmp;
137    unsigned long utmp = 0, sign = 0x100;
138
139    if (len > 1) {
140        /*
141         * Check possible pad byte.  Worst case, we're skipping past actual
142         * content, but since that's only with 0x00 and 0xff and we set neg
143         * accordingly, the result will be correct in the end anyway.
144         */
145        switch (cont[0]) {
146        case 0xff:
147            cont++;
148            len--;
149            sign = 0xff;
150            break;
151        case 0:
152            cont++;
153            len--;
154            sign = 0;
155            break;
156        }
157    }
158    if (len > (int)sizeof(long)) {
159        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
160        return 0;
161    }
162
163    if (sign == 0x100) {
164        /* Is it negative? */
165        if (len && (cont[0] & 0x80))
166            sign = 0xff;
167        else
168            sign = 0;
169    } else if (((sign ^ cont[0]) & 0x80) == 0) { /* same sign bit? */
170        ASN1err(ASN1_F_LONG_C2I, ASN1_R_ILLEGAL_PADDING);
171        return 0;
172    }
173    utmp = 0;
174    for (i = 0; i < len; i++) {
175        utmp <<= 8;
176        utmp |= cont[i] ^ sign;
177    }
178    ltmp = (long)utmp;
179    if (ltmp < 0) {
180        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
181        return 0;
182    }
183    if (sign)
184        ltmp = -ltmp - 1;
185    if (ltmp == it->size) {
186        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
187        return 0;
188    }
189    memcpy(pval, &ltmp, COPY_SIZE(*pval, ltmp));
190    return 1;
191}
192
193static int long_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
194                      int indent, const ASN1_PCTX *pctx)
195{
196    long l;
197
198    memcpy(&l, pval, COPY_SIZE(*pval, l));
199    return BIO_printf(out, "%ld\n", l);
200}
201#endif
202