518 lines
16 KiB
C++
518 lines
16 KiB
C++
//+-------------------------------------------------------------------------
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// Microsoft Windows
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//
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// Copyright (C) Microsoft Corporation, 2001 - 2001
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//
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// File: asn1util.cpp
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//
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// Contents: Minimal ASN.1 utility helper functions.
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//
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// Functions: MinAsn1DecodeLength
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// MinAsn1ExtractContent
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// MinAsn1ExtractValues
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//
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// MinAsn1FindExtension
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// MinAsn1FindAttribute
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// MinAsn1ExtractParsedCertificatesFromSignedData
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//
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// History: 15-Jan-01 philh created
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//--------------------------------------------------------------------------
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#include "global.hxx"
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//+-------------------------------------------------------------------------
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// Get the number of contents octets in a definite-length BER-encoding.
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//
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// Parameters:
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// pcbContent - receives the number of contents octets
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// pbLength - points to the first length octet
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// cbBER - number of bytes remaining in the BER encoding
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//
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// Returns:
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// success - the number of bytes in the length field, > 0
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// failure - < 0
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//
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// One of the following failure values can be returned:
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// MINASN1_LENGTH_TOO_LARGE
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// MINASN1_INSUFFICIENT_DATA
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// MINASN1_UNSUPPORTED_INDEFINITE_LENGTH
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//--------------------------------------------------------------------------
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LONG
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WINAPI
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MinAsn1DecodeLength(
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OUT DWORD *pcbContent,
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IN const BYTE *pbLength,
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IN DWORD cbBER)
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{
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long i;
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BYTE cbLength;
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const BYTE *pb;
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if (cbBER < 1)
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goto TooLittleData;
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if (0x80 == *pbLength)
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goto IndefiniteLength;
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// determine the number of length octets and contents octets
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if ((cbLength = *pbLength) & 0x80) {
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cbLength &= ~0x80; // low 7 bits have number of bytes
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if (cbLength > 4)
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goto LengthTooLargeError;
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if (cbLength >= cbBER)
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goto TooLittleData;
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*pcbContent = 0;
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for (i=cbLength, pb=pbLength+1; i>0; i--, pb++)
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*pcbContent = (*pcbContent << 8) + (const DWORD)*pb;
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i = cbLength + 1;
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} else {
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*pcbContent = (DWORD)cbLength;
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i = 1;
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}
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CommonReturn:
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return i; // how many bytes there were in the length field
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LengthTooLargeError:
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i = MINASN1_LENGTH_TOO_LARGE;
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goto CommonReturn;
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IndefiniteLength:
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i = MINASN1_UNSUPPORTED_INDEFINITE_LENGTH;
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goto CommonReturn;
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TooLittleData:
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i = MINASN1_INSUFFICIENT_DATA;
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goto CommonReturn;
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}
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//+-------------------------------------------------------------------------
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// Point to the content octets in a definite-length BER-encoded blob.
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//
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// Returns:
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// success - the number of bytes skipped, > 0
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// failure - < 0
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//
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// One of the following failure values can be returned:
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// MINASN1_LENGTH_TOO_LARGE
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// MINASN1_INSUFFICIENT_DATA
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// MINASN1_UNSUPPORTED_INDEFINITE_LENGTH
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//
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// Assumption: pbData points to a definite-length BER-encoded blob.
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// If *pcbContent isn't within cbBER, MINASN1_INSUFFICIENT_DATA
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// is returned.
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//--------------------------------------------------------------------------
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LONG
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WINAPI
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MinAsn1ExtractContent(
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IN const BYTE *pbBER,
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IN DWORD cbBER,
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OUT DWORD *pcbContent,
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OUT const BYTE **ppbContent)
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{
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#define TAG_MASK 0x1f
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DWORD cbIdentifier;
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DWORD cbContent;
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LONG cbLength;
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LONG lHeader;
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const BYTE *pb = pbBER;
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if (0 == cbBER--)
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goto TooLittleData;
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// Skip over the identifier octet(s)
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if (TAG_MASK == (*pb++ & TAG_MASK)) {
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// high-tag-number form
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cbIdentifier = 2;
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while (TRUE) {
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if (0 == cbBER--)
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goto TooLittleData;
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if (0 == (*pb++ & 0x80))
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break;
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cbIdentifier++;
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}
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} else {
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// low-tag-number form
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cbIdentifier = 1;
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}
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if (0 > (cbLength = MinAsn1DecodeLength( &cbContent, pb, cbBER))) {
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lHeader = cbLength;
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goto CommonReturn;
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}
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if (cbContent > (cbBER - cbLength))
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goto TooLittleData;
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pb += cbLength;
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*pcbContent = cbContent;
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*ppbContent = pb;
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lHeader = cbLength + cbIdentifier;
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CommonReturn:
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return lHeader;
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TooLittleData:
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lHeader = MINASN1_INSUFFICIENT_DATA;
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goto CommonReturn;
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}
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typedef struct _STEP_INTO_STACK_ENTRY {
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const BYTE *pb;
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DWORD cb;
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BOOL fSkipIntoValues;
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} STEP_INTO_STACK_ENTRY, *PSTEP_INTO_STACK_ENTRY;
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#define MAX_STEP_INTO_DEPTH 8
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//+-------------------------------------------------------------------------
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// Extract one or more tagged values from the ASN.1 encoded byte array.
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//
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// Either steps into the value's content octets (MINASN1_STEP_INTO_VALUE_OP or
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// MINASN1_OPTIONAL_STEP_INTO_VALUE_OP) or steps over the value's tag,
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// length and content octets (MINASN1_STEP_OVER_VALUE_OP or
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// MINASN1_OPTIONAL_STEP_OVER_VALUE_OP).
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//
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// You can step out of a stepped into sequence via MINASN1_STEP_OUT_VALUE_OP.
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//
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// For tag matching, only supports single byte tags.
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//
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// Only definite-length ASN.1 is supported.
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//
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// *pcValue is updated with the number of values successfully extracted.
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//
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// Returns:
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// success - >= 0 => length of all bytes consumed through the last value
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// extracted. For STEP_INTO, only the tag and length
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// octets.
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// failure - < 0 => negative (offset + 1) of first bad tagged value
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//
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// A non-NULL rgValueBlob[] is updated with the pointer to and length of the
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// tagged value or its content octets. The rgValuePara[].dwIndex is used to
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// index into rgValueBlob[]. For OPTIONAL_STEP_OVER or
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// OPTIONAL_STEP_INTO, if no more bytes in the outer SEQUENCE or if the tag
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// isn't found, pbData and cbData are set to 0. Additioanlly, for
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// OPTIONAL_STEP_INTO, all subsequent values are skipped and their
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// rgValueBlob[] entries zeroed until a STEP_OUT is encountered.
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//
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// If MINASN1_RETURN_VALUE_BLOB_FLAG is set, pbData points to
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// the tag. cbData includes the tag, length and content octets.
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//
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// If MINASN1_RETURN_CONTENT_BLOB_FLAG is set, pbData points to the content
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// octets. cbData includes only the content octets.
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//
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// If neither BLOB_FLAG is set, rgValueBlob[] isn't updated.
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//
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// For MINASN1_RETURN_CONTENT_BLOB_FLAG of a BITSTRING, pbData is
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// advanced past the first contents octet containing the number of
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// unused bits and cbData has been decremented by 1. If cbData > 0, then,
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// *(pbData - 1) will contain the number of unused bits.
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//--------------------------------------------------------------------------
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LONG
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WINAPI
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MinAsn1ExtractValues(
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IN const BYTE *pbEncoded,
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IN DWORD cbEncoded,
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IN OUT DWORD *pcValuePara,
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IN const MINASN1_EXTRACT_VALUE_PARA *rgValuePara,
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IN DWORD cValueBlob,
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OUT OPTIONAL PCRYPT_DER_BLOB rgValueBlob
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)
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{
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DWORD cValue = *pcValuePara;
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const BYTE *pb = pbEncoded;
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DWORD cb = cbEncoded;
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BOOL fSkipIntoValues = FALSE;
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DWORD iValue;
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LONG lAllValues;
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STEP_INTO_STACK_ENTRY rgStepIntoStack[MAX_STEP_INTO_DEPTH];
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DWORD dwStepIntoDepth = 0;
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for (iValue = 0; iValue < cValue; iValue++) {
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DWORD dwParaFlags = rgValuePara[iValue].dwFlags;
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DWORD dwOp = dwParaFlags & MINASN1_MASK_VALUE_OP;
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const BYTE *pbParaTag = rgValuePara[iValue].rgbTag;
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DWORD dwIndex = rgValuePara[iValue].dwIndex;
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BOOL fValueBlob = (dwParaFlags & (MINASN1_RETURN_VALUE_BLOB_FLAG |
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MINASN1_RETURN_CONTENT_BLOB_FLAG)) && rgValueBlob &&
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(dwIndex < cValueBlob);
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BOOL fSkipValue = FALSE;
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LONG lTagLength;
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DWORD cbContent;
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const BYTE *pbContent;
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DWORD cbValue;
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if (MINASN1_STEP_OUT_VALUE_OP == dwOp) {
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// Unstack and advance past the last STEP_INTO
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if (0 == dwStepIntoDepth)
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goto InvalidStepOutOp;
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dwStepIntoDepth--;
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pb = rgStepIntoStack[dwStepIntoDepth].pb;
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cb = rgStepIntoStack[dwStepIntoDepth].cb;
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fSkipIntoValues = rgStepIntoStack[dwStepIntoDepth].fSkipIntoValues;
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continue;
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}
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if (fSkipIntoValues) {
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// For an omitted OPTIONAL_STEP_INTO, all of its included values
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// are also omitted.
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fSkipValue = TRUE;
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} else if (0 == cb) {
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if (!(MINASN1_OPTIONAL_STEP_INTO_VALUE_OP == dwOp ||
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MINASN1_OPTIONAL_STEP_OVER_VALUE_OP == dwOp))
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goto TooLittleData;
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fSkipValue = TRUE;
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} else if (pbParaTag) {
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// Assumption: single byte tag for doing comparison
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// Check if the encoded tag matches one of the expected tags
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BYTE bEncodedTag;
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BYTE bParaTag;
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bEncodedTag = *pb;
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while ((bParaTag = *pbParaTag) && bParaTag != bEncodedTag)
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pbParaTag++;
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if (0 == bParaTag) {
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if (!(MINASN1_OPTIONAL_STEP_INTO_VALUE_OP == dwOp ||
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MINASN1_OPTIONAL_STEP_OVER_VALUE_OP == dwOp))
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goto InvalidTag;
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fSkipValue = TRUE;
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}
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}
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if (fSkipValue) {
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if (fValueBlob) {
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rgValueBlob[dwIndex].pbData = NULL;
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rgValueBlob[dwIndex].cbData = 0;
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}
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if (MINASN1_STEP_INTO_VALUE_OP == dwOp ||
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MINASN1_OPTIONAL_STEP_INTO_VALUE_OP == dwOp) {
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// Stack this skipped STEP_INTO
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if (MAX_STEP_INTO_DEPTH <= dwStepIntoDepth)
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goto ExceededStepIntoDepth;
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rgStepIntoStack[dwStepIntoDepth].pb = pb;
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rgStepIntoStack[dwStepIntoDepth].cb = cb;
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rgStepIntoStack[dwStepIntoDepth].fSkipIntoValues =
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fSkipIntoValues;
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dwStepIntoDepth++;
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fSkipIntoValues = TRUE;
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}
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continue;
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}
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lTagLength = MinAsn1ExtractContent(
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pb,
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cb,
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&cbContent,
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&pbContent
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);
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if (0 >= lTagLength)
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goto InvalidTagOrLength;
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cbValue = cbContent + lTagLength;
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if (fValueBlob) {
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if (dwParaFlags & MINASN1_RETURN_CONTENT_BLOB_FLAG) {
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rgValueBlob[dwIndex].pbData = (BYTE *) pbContent;
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rgValueBlob[dwIndex].cbData = cbContent;
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if (MINASN1_TAG_BITSTRING == *pb) {
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if (0 < cbContent) {
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// Advance past the first contents octet containing
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// the number of unused bits
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rgValueBlob[dwIndex].pbData += 1;
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rgValueBlob[dwIndex].cbData -= 1;
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}
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}
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} else if (dwParaFlags & MINASN1_RETURN_VALUE_BLOB_FLAG) {
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rgValueBlob[dwIndex].pbData = (BYTE *) pb;
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rgValueBlob[dwIndex].cbData = cbValue;
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}
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}
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switch (dwOp) {
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case MINASN1_STEP_INTO_VALUE_OP:
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case MINASN1_OPTIONAL_STEP_INTO_VALUE_OP:
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// Stack this STEP_INTO
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if (MAX_STEP_INTO_DEPTH <= dwStepIntoDepth)
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goto ExceededStepIntoDepth;
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rgStepIntoStack[dwStepIntoDepth].pb = pb + cbValue;
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rgStepIntoStack[dwStepIntoDepth].cb = cb - cbValue;
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assert(!fSkipIntoValues);
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rgStepIntoStack[dwStepIntoDepth].fSkipIntoValues = FALSE;
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dwStepIntoDepth++;
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pb = pbContent;
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cb = cbContent;
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break;
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case MINASN1_STEP_OVER_VALUE_OP:
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case MINASN1_OPTIONAL_STEP_OVER_VALUE_OP:
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pb += cbValue;
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cb -= cbValue;
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break;
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default:
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goto InvalidArg;
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}
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}
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lAllValues = (LONG)(pb - pbEncoded);
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assert((DWORD) lAllValues <= cbEncoded);
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CommonReturn:
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*pcValuePara = iValue;
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return lAllValues;
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InvalidStepOutOp:
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TooLittleData:
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InvalidTag:
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ExceededStepIntoDepth:
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InvalidTagOrLength:
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InvalidArg:
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lAllValues = -((LONG)(pb - pbEncoded)) - 1;
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goto CommonReturn;
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}
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//+-------------------------------------------------------------------------
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// Find an extension identified by its Encoded Object Identifier.
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//
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// Searches the list of parsed extensions returned by
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// MinAsn1ParseExtensions().
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//
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// If found, returns pointer to the rgExtBlob[MINASN1_EXT_BLOB_CNT].
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// Otherwise, returns NULL.
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//--------------------------------------------------------------------------
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PCRYPT_DER_BLOB
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WINAPI
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MinAsn1FindExtension(
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IN PCRYPT_DER_BLOB pEncodedOIDBlob,
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IN DWORD cExt,
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IN CRYPT_DER_BLOB rgrgExtBlob[][MINASN1_EXT_BLOB_CNT]
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)
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{
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DWORD i;
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DWORD cbOID = pEncodedOIDBlob->cbData;
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const BYTE *pbOID = pEncodedOIDBlob->pbData;
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for (i = 0; i < cExt; i++) {
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if (cbOID == rgrgExtBlob[i][MINASN1_EXT_OID_IDX].cbData
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&&
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0 == memcmp(pbOID, rgrgExtBlob[i][MINASN1_EXT_OID_IDX].pbData,
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cbOID))
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return rgrgExtBlob[i];
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}
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return NULL;
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}
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//+-------------------------------------------------------------------------
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// Find the first attribute identified by its Encoded Object Identifier.
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//
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// Searches the list of parsed attributes returned by
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// MinAsn1ParseAttributes().
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//
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// If found, returns pointer to the rgAttrBlob[MINASN1_ATTR_BLOB_CNT].
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// Otherwise, returns NULL.
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//--------------------------------------------------------------------------
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PCRYPT_DER_BLOB
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WINAPI
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MinAsn1FindAttribute(
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IN PCRYPT_DER_BLOB pEncodedOIDBlob,
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IN DWORD cAttr,
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IN CRYPT_DER_BLOB rgrgAttrBlob[][MINASN1_ATTR_BLOB_CNT]
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)
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{
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DWORD i;
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DWORD cbOID = pEncodedOIDBlob->cbData;
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const BYTE *pbOID = pEncodedOIDBlob->pbData;
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for (i = 0; i < cAttr; i++) {
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if (cbOID == rgrgAttrBlob[i][MINASN1_ATTR_OID_IDX].cbData
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&&
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0 == memcmp(pbOID, rgrgAttrBlob[i][MINASN1_ATTR_OID_IDX].pbData,
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cbOID))
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return rgrgAttrBlob[i];
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}
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return NULL;
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}
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//+-------------------------------------------------------------------------
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// Parses an ASN.1 encoded PKCS #7 Signed Data Message to extract and
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// parse the X.509 certificates it contains.
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//
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// Assumes the PKCS #7 message is definite length encoded.
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// Assumes PKCS #7 version 1.5, ie, not the newer CMS version.
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//
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// Upon input, *pcCert contains the maximum number of parsed certificates
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// that can be returned. Updated with the number of certificates processed.
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//
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// If the encoded message was successfully parsed, TRUE is returned
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// with *pcCert updated with the number of parsed certificates. Otherwise,
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// FALSE is returned for a parse error.
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// Returns:
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// success - >= 0 => bytes skipped, length of the encoded certificates
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// processed.
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// failure - < 0 => negative (offset + 1) of first bad tagged value
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// from beginning of message.
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//
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// The rgrgCertBlob[][] is updated with pointer to and length of the
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// fields in the encoded certificate. See MinAsn1ParseCertificate for the
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// field definitions.
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//--------------------------------------------------------------------------
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LONG
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WINAPI
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MinAsn1ExtractParsedCertificatesFromSignedData(
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IN const BYTE *pbEncoded,
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IN DWORD cbEncoded,
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IN OUT DWORD *pcCert,
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OUT CRYPT_DER_BLOB rgrgCertBlob[][MINASN1_CERT_BLOB_CNT]
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)
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{
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LONG lSkipped;
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CRYPT_DER_BLOB rgSignedDataBlob[MINASN1_SIGNED_DATA_BLOB_CNT];
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lSkipped = MinAsn1ParseSignedData(
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pbEncoded,
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cbEncoded,
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rgSignedDataBlob
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);
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if (0 >= lSkipped)
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goto ParseError;
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lSkipped = MinAsn1ParseSignedDataCertificates(
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&rgSignedDataBlob[MINASN1_SIGNED_DATA_CERTS_IDX],
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pcCert,
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rgrgCertBlob
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);
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if (0 > lSkipped) {
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assert(rgSignedDataBlob[MINASN1_SIGNED_DATA_CERTS_IDX].pbData >
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pbEncoded);
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lSkipped -= rgSignedDataBlob[MINASN1_SIGNED_DATA_CERTS_IDX].pbData -
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pbEncoded;
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goto ParseError;
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}
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CommonReturn:
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return lSkipped;
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ParseError:
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*pcCert = 0;
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goto CommonReturn;
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}
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