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 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 } 101 102 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