1 /*
2 * src/lib/krb5/asn.1/asn1_get.c
3 *
4 * Copyright 1994 by the Massachusetts Institute of Technology.
5 * All Rights Reserved.
6 *
7 * Export of this software from the United States of America may
8 * require a specific license from the United States Government.
9 * It is the responsibility of any person or organization contemplating
10 * export to obtain such a license before exporting.
11 *
12 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13 * distribute this software and its documentation for any purpose and
14 * without fee is hereby granted, provided that the above copyright
15 * notice appear in all copies and that both that copyright notice and
16 * this permission notice appear in supporting documentation, and that
17 * the name of M.I.T. not be used in advertising or publicity pertaining
18 * to distribution of the software without specific, written prior
19 * permission. Furthermore if you modify this software you must label
20 * your software as modified software and not distribute it in such a
21 * fashion that it might be confused with the original M.I.T. software.
22 * M.I.T. makes no representations about the suitability of
23 * this software for any purpose. It is provided "as is" without express
24 * or implied warranty.
25 */
26
27 #include "asn1_get.h"
28
29 asn1_error_code
asn1_get_tag_2(asn1buf * buf,taginfo * t)30 asn1_get_tag_2(asn1buf *buf, taginfo *t)
31 {
32 asn1_error_code retval;
33
34 if (buf == NULL || buf->base == NULL ||
35 buf->bound - buf->next + 1 <= 0) {
36 t->tagnum = ASN1_TAGNUM_CEILING; /* emphatically not an EOC tag */
37 t->asn1class = UNIVERSAL;
38 t->construction = PRIMITIVE;
39 t->length = 0;
40 t->indef = 0;
41 return 0;
42 }
43 {
44 /* asn1_get_id(buf, t) */
45 asn1_tagnum tn=0;
46 asn1_octet o;
47
48 #define ASN1_CLASS_MASK 0xC0
49 #define ASN1_CONSTRUCTION_MASK 0x20
50 #define ASN1_TAG_NUMBER_MASK 0x1F
51
52 retval = asn1buf_remove_octet(buf,&o);
53 if (retval)
54 return retval;
55
56 t->asn1class = (asn1_class)(o&ASN1_CLASS_MASK);
57 t->construction = (asn1_construction)(o&ASN1_CONSTRUCTION_MASK);
58 if ((o&ASN1_TAG_NUMBER_MASK) != ASN1_TAG_NUMBER_MASK){
59 /* low-tag-number form */
60 t->tagnum = (asn1_tagnum)(o&ASN1_TAG_NUMBER_MASK);
61 } else {
62 /* high-tag-number form */
63 do {
64 retval = asn1buf_remove_octet(buf,&o);
65 if (retval) return retval;
66 tn = (tn<<7) + (asn1_tagnum)(o&0x7F);
67 }while(o&0x80);
68 t->tagnum = tn;
69 }
70 }
71
72 {
73 /* asn1_get_length(buf, t) */
74 asn1_octet o;
75
76 t->indef = 0;
77 retval = asn1buf_remove_octet(buf,&o);
78 if (retval) return retval;
79 if ((o&0x80) == 0) {
80 t->length = (int)(o&0x7F);
81 } else {
82 int num;
83 int len=0;
84
85 for (num = (int)(o&0x7F); num>0; num--) {
86 retval = asn1buf_remove_octet(buf,&o);
87 if(retval) return retval;
88 len = (len<<8) + (int)o;
89 }
90 if (len < 0)
91 return ASN1_OVERRUN;
92 if (!len)
93 t->indef = 1;
94 t->length = len;
95 }
96 }
97 if (t->indef && t->construction != CONSTRUCTED)
98 return ASN1_MISMATCH_INDEF;
99 return 0;
100 }
101
asn1_get_sequence(asn1buf * buf,unsigned int * retlen,int * indef)102 asn1_error_code asn1_get_sequence(asn1buf *buf, unsigned int *retlen, int *indef)
103 {
104 taginfo t;
105 asn1_error_code retval;
106
107 retval = asn1_get_tag_2(buf, &t);
108 if (retval)
109 return retval;
110 if (t.asn1class != UNIVERSAL || t.construction != CONSTRUCTED ||
111 t.tagnum != ASN1_SEQUENCE)
112 return ASN1_BAD_ID;
113 if (retlen)
114 *retlen = t.length;
115 if (indef)
116 *indef = t.indef;
117 return 0;
118 }
119