guidfromname.cpp

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

// GuidFromName

/**

Algorithm from Internet Draft document "UUIDs and GUIDs"
By Paul J. Leach and Rich Sals, February 4, 1998.

This function has been adapted from the routines in the document
 uuid_create_from_name and format_uuid_v3

Changes from documented routines:
1. Changed all instances of uuid_t to GUID.
     uuid_t field time_low is GUID field Data1.
     uuid_t field time_mid is GUID field Data2.
     uuid_t field time_hi_and_version is GUID field Data3.
     uuid_t field clock_seq_hi_and_reserved is GUID field Data4[0].
     uuid_t field clock_seq_low is GUID field Data4[1].
     uuid_t field node[6] is GUID field Data4[2] through Data4[8].

2. Use a c++ implementation of the md5 cryptographic hash function.

3. Implemented the htonl, htons, ntohl, ntohs socket routines as inlines.

4. Renamed variables and types to suit my biases.


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Copyright(C) The Internet Society 1997. All Rights Reserved.

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The limited permissions granted above are perpetual and will not be revoked
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*/

#include "stdafx.h"

#include "md5.h"                // cryptographic hash function
#include "guidfromname.h"       // verify our function signature
#include "contract.h"

#if BIGENDIAN
#define BigEndian() true
#else
#define BigEndian() false
#endif

//=============================================================================
// htons, htonl, ntohs, ntohl equivalents copied and adapted from socket library.
//=============================================================================

// HostToNetworkLong converts a 32-bit long to network byte order

inline ULONG HostToNetworkLong(ULONG hostlong)
{
    LIMITED_METHOD_CONTRACT;

    if (BigEndian())
        return hostlong;
    else
        return  ( (hostlong >> 24) & 0x000000FFL) |
                ( (hostlong >>  8) & 0x0000FF00L) |
                ( (hostlong <<  8) & 0x00FF0000L) |
                ( (hostlong << 24) & 0xFF000000L);
}

// HostToNetworkLong converts a 16-bit short to network byte order

inline USHORT HostToNetworkShort(USHORT hostshort)
{
    LIMITED_METHOD_CONTRACT;

    if (BigEndian())
        return hostshort;
    else
        return ((hostshort >> 8) & 0x00FF) | ((hostshort << 8) & 0xFF00);
}

// NetworkToHostLong converts a 32-bit long to local host byte order

inline ULONG NetworkToHostLong(ULONG netlong)
{
    LIMITED_METHOD_CONTRACT;

    if (BigEndian())
        return netlong;
    else
        return  ( (netlong >> 24) & 0x000000FFL) |
                ( (netlong >>  8) & 0x0000FF00L) |
                ( (netlong <<  8) & 0x00FF0000L) |
                ( (netlong << 24) & 0xFF000000L);
}

// NetworkToHostShort converts a 16-bit short to local host byte order

inline USHORT NetworkToHostShort(USHORT netshort)
{
    LIMITED_METHOD_CONTRACT;

    if (BigEndian())
        return netshort;
    else
        return ((netshort >> 8) & 0x00FF) | ((netshort << 8) & 0xFF00);
}

//=============================================================================
// GuidFromName(GUID * pGuidResult, REFGUID refGuidNsid,
//              const void * pvName, DWORD dwcbName);
//=============================================================================

void GuidFromName
(
    GUID *  pGuidResult,        // resulting GUID
    REFGUID refGuidNsid,        // Name Space GUID, so identical names from
                                // different name spaces generate different GUIDs
    const void * pvName,        // the name from which to generate a GUID
    DWORD dwcbName              // name length in bytes
)
{
    STATIC_CONTRACT_NOTHROW;
    STATIC_CONTRACT_GC_NOTRIGGER;

    MD5         md5;            // Cryptographic hash class instance
    MD5HASHDATA md5HashData;    // 128-bit hash result
    GUID        guidNsid;       // context NameSpace GUID in network byte order

    GUID        guidTemp;

    // put name space ID in network byte order so it hashes the same
    // no matter what endian machine we're on
    guidNsid = refGuidNsid;

    // The sample code in the IETF draft document discards the result of
    // htonl and htons.  I've implemented what I think is meant and I've
    // sent a note to the author asking for confirmation that this is
    // his intent.
    if (!BigEndian())   // evaluated at compile time in retail builds
    {
        guidNsid.Data1 = HostToNetworkLong (guidNsid.Data1);
        guidNsid.Data2 = HostToNetworkShort(guidNsid.Data2);
        guidNsid.Data3 = HostToNetworkShort(guidNsid.Data3);
    }

    md5.Init();
    md5.HashMore(&guidNsid, sizeof(GUID));
    md5.HashMore(pvName, dwcbName);
    md5.GetHashValue(&md5HashData);

    // the hash is in network byte order at this point
    memcpy(&guidTemp, &md5HashData, sizeof(GUID));

    // Remainder adapted from function "format_uuid_v3" in IETF draft document
    // Construct a version 3 uuid with the pseudo-random number plus a few constants.
    // convert GUID from network order to local byte order
    if (!BigEndian())   // evaluated at compile time in retail builds
    {
        guidTemp.Data1 = NetworkToHostLong (guidTemp.Data1);
        guidTemp.Data2 = NetworkToHostShort(guidTemp.Data2);
        guidTemp.Data3 = NetworkToHostShort(guidTemp.Data3);
    }

    // set version number
    guidTemp.Data3 &= 0x0FFF;   // clear version number nibble
    guidTemp.Data3 |= (3 << 12);// set version 3 = name-based

    // set variant field
    guidTemp.Data4[0] &= 0x3F;  // clear variant bits
    guidTemp.Data4[0] |= 0x80;  // set variant = 100b

    // If two GuidFromName calls were made from different threads with the same parameters,
    // we may get incorrect result even though the expected result is the same, because
    // GuidFromName is operating on the same pGuidResult buffer.
    // Fix this problem by using a temp GUID buffer and then copy to the pGuidResult buffer.
    memcpy(pGuidResult, &guidTemp, sizeof(GUID));
}


// This guid is used for calling GuidFromName function as COM+ runtime uniqualifier
//
// {69F9CBC9-DA05-11d1-9408-0000F8083460}
static const GUID COMPLUS_RUNTIME_GUID = {0x69f9cbc9, 0xda05, 0x11d1,
        {0x94, 0x8, 0x0, 0x0, 0xf8, 0x8, 0x34, 0x60}};

void CorGuidFromNameW
(
    GUID *  pGuidResult,        // resulting GUID
    LPCWSTR wzName,             // the unicode name from which to generate a GUID
    SIZE_T  cchName             // name length in count of unicode character
)
{
    WRAPPER_NO_CONTRACT;

    GuidFromName(
        pGuidResult,
        COMPLUS_RUNTIME_GUID,
        wzName,
        (DWORD)((cchName == (SIZE_T) -1 ? (wcslen(wzName)+1) : cchName) * sizeof(WCHAR)));
}