www.pudn.com > snmp.rar > octets.c

/*++ 
 
Copyright (c) 1992-1997  Microsoft Corporation 
 
Module Name: 
 
    octets.c 
 
Abstract: 
 
    Contains routines to manipulate octet strings. 
 
        SnmpUtilOctetsCpy 
        SnmpUtilOctetsFree 
 
Environment: 
 
    User Mode - Win32 
 
Revision History: 
 
--*/ 
 
/////////////////////////////////////////////////////////////////////////////// 
//                                                                           // 
// Include files                                                             // 
//                                                                           // 
/////////////////////////////////////////////////////////////////////////////// 
 
#include  
#include  
 
 
/////////////////////////////////////////////////////////////////////////////// 
//                                                                           // 
// Public Procedures                                                         // 
//                                                                           // 
/////////////////////////////////////////////////////////////////////////////// 
 
SNMPAPI 
SNMP_FUNC_TYPE 
SnmpUtilOctetsCpy( 
    AsnOctetString * pOctetsDst, 
    AsnOctetString * pOctetsSrc 
    ) 
 
/*++ 
 
Routine Description: 
 
    Copy an octet string. 
 
Arguments: 
 
    pOctetsDst - pointer to structure to receive octets. 
 
    pOctetsSrc - pointer to octets to copy. 
 
Return Values: 
 
    Returns SNMPAPI_NOERROR if successful.  
 
--*/ 
 
{ 
    SNMPAPI nResult = SNMPAPI_ERROR; 
 
    // validate pointers 
    if (pOctetsDst != NULL) { 
         
        // initialize 
        pOctetsDst->stream  = NULL; 
        pOctetsDst->length  = 0; 
        pOctetsDst->dynamic = FALSE; 
 
        // make sure there are bytes 
        if ((pOctetsSrc != NULL) && 
            (pOctetsSrc->stream != NULL) && 
            (pOctetsSrc->length != 0)) { 
 
            // attempt to allocate octet string 
            pOctetsDst->stream = SnmpUtilMemAlloc(pOctetsSrc->length); 
             
            // validate pointer 
            if (pOctetsDst->stream != NULL) { 
 
                // denote allocated type 
                pOctetsDst->dynamic = TRUE; 
 
                // transfer octet string length 
                pOctetsDst->length = pOctetsSrc->length; 
 
                // copy 
                memcpy(pOctetsDst->stream, 
                       pOctetsSrc->stream, 
                       pOctetsSrc->length 
                       ); 
 
                nResult = SNMPAPI_NOERROR; // success... 
 
            } else { 
             
                SNMPDBG(( 
                    SNMP_LOG_ERROR, 
                    "SNMP: API: could not allocate octet string.\n" 
                    )); 
 
                SetLastError(SNMP_MEM_ALLOC_ERROR); 
            } 
 
        } else { 
 
            // copying null string 
            nResult = SNMPAPI_NOERROR; 
        } 
 
    } else { 
 
        SNMPDBG(( 
            SNMP_LOG_ERROR, 
            "SNMP: API: null octet string pointer.\n" 
            )); 
 
        SetLastError(ERROR_INVALID_PARAMETER); 
    } 
 
    return nResult; 
} 
 
 
VOID 
SNMP_FUNC_TYPE 
SnmpUtilOctetsFree( 
    AsnOctetString * pOctets 
    ) 
 
/*++ 
 
Routine Description: 
 
    Releases memory for an octet string. 
 
Arguments: 
 
    pOctets - pointer to octets to release. 
 
Return Values: 
 
    None.  
 
--*/ 
 
{ 
    // validate pointers 
    if ((pOctets != NULL) && 
        (pOctets->stream != NULL) &&  
        (pOctets->dynamic == TRUE)) { 
 
        // release memory for octets 
        SnmpUtilMemFree(pOctets->stream); 
 
        // re-initialize 
        pOctets->dynamic = FALSE; 
        pOctets->stream  = NULL; 
        pOctets->length  = 0; 
    } 
} 
 
 
SNMPAPI 
SNMP_FUNC_TYPE  
SnmpUtilOctetsNCmp( 
    AsnOctetString * pOctets1,  
    AsnOctetString * pOctets2, 
    UINT             nChars 
    ) 
 
/*++ 
 
Routine Description: 
 
    Compares two octet strings up to a certain number of characters. 
 
Arguments: 
 
    pOctets1 - pointer to first octet string. 
 
    pOctets2 - pointer to second octet string. 
 
    nChars - maximum characters to compare. 
 
Return Values: 
 
    < 0   first parameter is 'less than' second. 
      0   first parameter is 'equal to' second. 
    > 0   first parameter is 'greater than' second. 
 
--*/ 
 
{ 
    UINT i = 0; 
    INT nResult = 0; 
 
    // validate pointers 
    if ((pOctets1 != NULL) && 
        (pOctets2 != NULL)) { 
 
        // calculate maximum number of subidentifiers to compare 
        UINT nMaxChars = min(nChars, min(pOctets1->length, pOctets2->length)); 
 
        // loop through the subidentifiers 
        while((nResult == 0) && (i < nMaxChars)) { 
 
            // compare each subidentifier 
            nResult = pOctets1->stream[i] - pOctets2->stream[i++]; 
        } 
 
        // check for second being subset 
        if ((nResult == 0) && (i < nChars)) { 
 
            // determine order by length of oid 
            nResult = pOctets1->length - pOctets2->length; 
        } 
    } 
     
    return nResult; 
}  
 
 
SNMPAPI 
SNMP_FUNC_TYPE  
SnmpUtilOctetsCmp( 
    AsnOctetString * pOctets1,  
    AsnOctetString * pOctets2 
    ) 
 
/*++ 
 
Routine Description: 
 
    Compares two octet strings. 
 
Arguments: 
 
    pOctets1 - pointer to first octet string. 
 
    pOctets2 - pointer to second octet string. 
 
Return Values: 
 
    < 0   first parameter is 'less than' second. 
      0   first parameter is 'equal to' second. 
    > 0   first parameter is 'greater than' second. 
 
--*/ 
 
{ 
    // forward request above 
    return SnmpUtilOctetsNCmp( 
                pOctets1, 
                pOctets2, 
                max(pOctets1->length,pOctets2->length) 
                ); 
}