extensions/auth/nsAuthSSPI.cpp
author Kate McKinley <kmckinley@mozilla.com>
Tue, 26 Jul 2016 13:03:00 +0800
changeset 346851 8dc198cd46fff3b1f6e39ea6e80bb4507bf2cdbe
parent 274591 dd750b3d18c5c96a0a04069eefd8bca79dac14d2
child 394259 2e4be7d6a0a85c13e5205584dd1f4066d92324a4
permissions -rw-r--r--
Bug 1246540 HSTS Priming Proof of Concept HSTS priming changes the order of mixed-content blocking and HSTS upgrades, and adds a priming request to check if a mixed-content load is accesible over HTTPS and the server supports upgrading via the Strict-Transport-Security header. Every call site that uses AsyncOpen2 passes through the mixed-content blocker, and has a LoadInfo. If the mixed-content blocker marks the load as needing HSTS priming, nsHttpChannel will build and send an HSTS priming request on the same URI with the scheme upgraded to HTTPS. If the server allows the upgrade, then channel performs an internal redirect to the HTTPS URI, otherwise use the result of mixed-content blocker to allow or block the load. nsISiteSecurityService adds an optional boolean out parameter to determine if the HSTS state is already cached for negative assertions. If the host has been probed within the previous 24 hours, no HSTS priming check will be sent. (r=ckerschb,r=mayhemer,r=jld,r=smaug,r=dkeeler,r=jmaher,p=ally)

/* vim:set ts=4 sw=4 sts=4 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

//
// Negotiate Authentication Support Module
//
// Described by IETF Internet draft: draft-brezak-kerberos-http-00.txt
// (formerly draft-brezak-spnego-http-04.txt)
//
// Also described here:
// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsecure/html/http-sso-1.asp
//

#include "nsAuthSSPI.h"
#include "nsIServiceManager.h"
#include "nsIDNSService.h"
#include "nsIDNSRecord.h"
#include "nsNetCID.h"
#include "nsCOMPtr.h"
#include "nsICryptoHash.h"
#include "mozilla/Telemetry.h"

#include <windows.h>

#define SEC_SUCCESS(Status) ((Status) >= 0)

#ifndef KERB_WRAP_NO_ENCRYPT
#define KERB_WRAP_NO_ENCRYPT 0x80000001
#endif

#ifndef SECBUFFER_PADDING
#define SECBUFFER_PADDING 9
#endif

#ifndef SECBUFFER_STREAM
#define SECBUFFER_STREAM 10
#endif

//-----------------------------------------------------------------------------

static const wchar_t *const pTypeName [] = {
    L"Kerberos",
    L"Negotiate",
    L"NTLM"
};

#ifdef DEBUG
#define CASE_(_x) case _x: return # _x;
static const char *MapErrorCode(int rc)
{
    switch (rc) {
    CASE_(SEC_E_OK)
    CASE_(SEC_I_CONTINUE_NEEDED)
    CASE_(SEC_I_COMPLETE_NEEDED)
    CASE_(SEC_I_COMPLETE_AND_CONTINUE)
    CASE_(SEC_E_INCOMPLETE_MESSAGE)
    CASE_(SEC_I_INCOMPLETE_CREDENTIALS)
    CASE_(SEC_E_INVALID_HANDLE)
    CASE_(SEC_E_TARGET_UNKNOWN)
    CASE_(SEC_E_LOGON_DENIED)
    CASE_(SEC_E_INTERNAL_ERROR)
    CASE_(SEC_E_NO_CREDENTIALS)
    CASE_(SEC_E_NO_AUTHENTICATING_AUTHORITY)
    CASE_(SEC_E_INSUFFICIENT_MEMORY)
    CASE_(SEC_E_INVALID_TOKEN)
    }
    return "<unknown>";
}
#else
#define MapErrorCode(_rc) ""
#endif

//-----------------------------------------------------------------------------

static PSecurityFunctionTableW   sspi;

static nsresult
InitSSPI()
{
    LOG(("  InitSSPI\n"));

    sspi = InitSecurityInterfaceW();
    if (!sspi) {
        LOG(("InitSecurityInterfaceW failed"));
        return NS_ERROR_UNEXPECTED;
    }

    return NS_OK;
}

//-----------------------------------------------------------------------------

static nsresult
MakeSN(const char *principal, nsCString &result)
{
    nsresult rv;

    nsAutoCString buf(principal);

    // The service name looks like "protocol@hostname", we need to map
    // this to a value that SSPI expects.  To be consistent with IE, we
    // need to map '@' to '/' and canonicalize the hostname.
    int32_t index = buf.FindChar('@');
    if (index == kNotFound)
        return NS_ERROR_UNEXPECTED;
    
    nsCOMPtr<nsIDNSService> dns = do_GetService(NS_DNSSERVICE_CONTRACTID, &rv);
    if (NS_FAILED(rv))
        return rv;

    // This could be expensive if our DNS cache cannot satisfy the request.
    // However, we should have at least hit the OS resolver once prior to
    // reaching this code, so provided the OS resolver has this information
    // cached, we should not have to worry about blocking on this function call
    // for very long.  NOTE: because we ask for the canonical hostname, we
    // might end up requiring extra network activity in cases where the OS
    // resolver might not have enough information to satisfy the request from
    // its cache.  This is not an issue in versions of Windows up to WinXP.
    nsCOMPtr<nsIDNSRecord> record;
    rv = dns->Resolve(Substring(buf, index + 1),
                      nsIDNSService::RESOLVE_CANONICAL_NAME,
                      getter_AddRefs(record));
    if (NS_FAILED(rv))
        return rv;

    nsAutoCString cname;
    rv = record->GetCanonicalName(cname);
    if (NS_SUCCEEDED(rv)) {
        result = StringHead(buf, index) + NS_LITERAL_CSTRING("/") + cname;
        LOG(("Using SPN of [%s]\n", result.get()));
    }
    return rv;
}

//-----------------------------------------------------------------------------

nsAuthSSPI::nsAuthSSPI(pType package)
    : mServiceFlags(REQ_DEFAULT)
    , mMaxTokenLen(0)
    , mPackage(package)
    , mCertDERData(nullptr)
    , mCertDERLength(0)
{
    memset(&mCred, 0, sizeof(mCred));
    memset(&mCtxt, 0, sizeof(mCtxt));
}

nsAuthSSPI::~nsAuthSSPI()
{
    Reset();

    if (mCred.dwLower || mCred.dwUpper) {
#ifdef __MINGW32__
        (sspi->FreeCredentialsHandle)(&mCred);
#else
        (sspi->FreeCredentialHandle)(&mCred);
#endif
        memset(&mCred, 0, sizeof(mCred));
    }
}

void
nsAuthSSPI::Reset()
{
    mIsFirst = true;

    if (mCertDERData){
        free(mCertDERData);
        mCertDERData = nullptr;
        mCertDERLength = 0;   
    }

    if (mCtxt.dwLower || mCtxt.dwUpper) {
        (sspi->DeleteSecurityContext)(&mCtxt);
        memset(&mCtxt, 0, sizeof(mCtxt));
    }
}

NS_IMPL_ISUPPORTS(nsAuthSSPI, nsIAuthModule)

NS_IMETHODIMP
nsAuthSSPI::Init(const char *serviceName,
                 uint32_t    serviceFlags,
                 const char16_t *domain,
                 const char16_t *username,
                 const char16_t *password)
{
    LOG(("  nsAuthSSPI::Init\n"));

    mIsFirst = true;
    mCertDERLength = 0;
    mCertDERData = nullptr;

    // The caller must supply a service name to be used. (For why we now require
    // a service name for NTLM, see bug 487872.)
    NS_ENSURE_TRUE(serviceName && *serviceName, NS_ERROR_INVALID_ARG);

    nsresult rv;

    // XXX lazy initialization like this assumes that we are single threaded
    if (!sspi) {
        rv = InitSSPI();
        if (NS_FAILED(rv))
            return rv;
    }
    SEC_WCHAR *package;

    package = (SEC_WCHAR *) pTypeName[(int)mPackage];

    if (mPackage == PACKAGE_TYPE_NTLM) {
        // (bug 535193) For NTLM, just use the uri host, do not do canonical host lookups.
        // The incoming serviceName is in the format: "protocol@hostname", SSPI expects
        // "<service class>/<hostname>", so swap the '@' for a '/'.
        mServiceName.Assign(serviceName);
        int32_t index = mServiceName.FindChar('@');
        if (index == kNotFound)
            return NS_ERROR_UNEXPECTED;
        mServiceName.Replace(index, 1, '/');
    }
    else {
        // Kerberos requires the canonical host, MakeSN takes care of this through a
        // DNS lookup.
        rv = MakeSN(serviceName, mServiceName);
        if (NS_FAILED(rv))
            return rv;
    }

    mServiceFlags = serviceFlags;

    SECURITY_STATUS rc;

    PSecPkgInfoW pinfo;
    rc = (sspi->QuerySecurityPackageInfoW)(package, &pinfo);
    if (rc != SEC_E_OK) {
        LOG(("%s package not found\n", package));
        return NS_ERROR_UNEXPECTED;
    }
    mMaxTokenLen = pinfo->cbMaxToken;
    (sspi->FreeContextBuffer)(pinfo);

    MS_TimeStamp useBefore;

    SEC_WINNT_AUTH_IDENTITY_W ai;
    SEC_WINNT_AUTH_IDENTITY_W *pai = nullptr;
    
    // domain, username, and password will be null if nsHttpNTLMAuth's ChallengeReceived
    // returns false for identityInvalid. Use default credentials in this case by passing
    // null for pai.
    if (username && password) {
        // Keep a copy of these strings for the duration
        mUsername.Assign(username);
        mPassword.Assign(password);
        mDomain.Assign(domain);
        ai.Domain = reinterpret_cast<unsigned short*>(mDomain.BeginWriting());
        ai.DomainLength = mDomain.Length();
        ai.User = reinterpret_cast<unsigned short*>(mUsername.BeginWriting());
        ai.UserLength = mUsername.Length();
        ai.Password = reinterpret_cast<unsigned short*>(mPassword.BeginWriting());
        ai.PasswordLength = mPassword.Length();
        ai.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;
        pai = &ai;
    }

    rc = (sspi->AcquireCredentialsHandleW)(nullptr,
                                           package,
                                           SECPKG_CRED_OUTBOUND,
                                           nullptr,
                                           pai,
                                           nullptr,
                                           nullptr,
                                           &mCred,
                                           &useBefore);
    if (rc != SEC_E_OK)
        return NS_ERROR_UNEXPECTED;

    static bool sTelemetrySent = false;
    if (!sTelemetrySent) {
        mozilla::Telemetry::Accumulate(
            mozilla::Telemetry::NTLM_MODULE_USED_2,
            serviceFlags & nsIAuthModule::REQ_PROXY_AUTH
                ? NTLM_MODULE_WIN_API_PROXY
                : NTLM_MODULE_WIN_API_DIRECT);
        sTelemetrySent = true;
    }

    LOG(("AcquireCredentialsHandle() succeeded.\n"));
    return NS_OK;
}

// The arguments inToken and inTokenLen are used to pass in the server
// certificate (when available) in the first call of the function. The
// second time these arguments hold an input token. 
NS_IMETHODIMP
nsAuthSSPI::GetNextToken(const void *inToken,
                         uint32_t    inTokenLen,
                         void      **outToken,
                         uint32_t   *outTokenLen)
{
    // String for end-point bindings.
    const char end_point[] = "tls-server-end-point:"; 
    const int end_point_length = sizeof(end_point) - 1;
    const int hash_size = 32;  // Size of a SHA256 hash.
    const int cbt_size = hash_size + end_point_length;
	
    SECURITY_STATUS rc;
    MS_TimeStamp ignored;

    DWORD ctxAttr, ctxReq = 0;
    CtxtHandle *ctxIn;
    SecBufferDesc ibd, obd;
    // Optional second input buffer for the CBT (Channel Binding Token)
    SecBuffer ib[2], ob;
    // Pointer to the block of memory that stores the CBT
    char* sspi_cbt = nullptr;
    SEC_CHANNEL_BINDINGS pendpoint_binding;

    LOG(("entering nsAuthSSPI::GetNextToken()\n"));

    if (!mCred.dwLower && !mCred.dwUpper) {
        LOG(("nsAuthSSPI::GetNextToken(), not initialized. exiting."));
        return NS_ERROR_NOT_INITIALIZED;
    }

    if (mServiceFlags & REQ_DELEGATE)
        ctxReq |= ISC_REQ_DELEGATE;
    if (mServiceFlags & REQ_MUTUAL_AUTH)
        ctxReq |= ISC_REQ_MUTUAL_AUTH;

    if (inToken) {
        if (mIsFirst) {
            // First time if it comes with a token,
            // the token represents the server certificate.
            mIsFirst = false;
            mCertDERLength = inTokenLen;
            mCertDERData = moz_xmalloc(inTokenLen);
            if (!mCertDERData)
                return NS_ERROR_OUT_OF_MEMORY;
            memcpy(mCertDERData, inToken, inTokenLen);

            // We are starting a new authentication sequence.  
            // If we have already initialized our
            // security context, then we're in trouble because it means that the
            // first sequence failed.  We need to bail or else we might end up in
            // an infinite loop.
            if (mCtxt.dwLower || mCtxt.dwUpper) {
                LOG(("Cannot restart authentication sequence!"));
                return NS_ERROR_UNEXPECTED;
            }
            ctxIn = nullptr;
            // The certificate needs to be erased before being passed 
            // to InitializeSecurityContextW().
            inToken = nullptr;
            inTokenLen = 0;
        } else {
            ibd.ulVersion = SECBUFFER_VERSION;
            ibd.cBuffers = 0;
            ibd.pBuffers = ib;
            
            // If we have stored a certificate, the Channel Binding Token
            // needs to be generated and sent in the first input buffer.
            if (mCertDERLength > 0) {
                // First we create a proper Endpoint Binding structure. 
                pendpoint_binding.dwInitiatorAddrType = 0;
                pendpoint_binding.cbInitiatorLength = 0;
                pendpoint_binding.dwInitiatorOffset = 0;
                pendpoint_binding.dwAcceptorAddrType = 0;
                pendpoint_binding.cbAcceptorLength = 0;
                pendpoint_binding.dwAcceptorOffset = 0;
                pendpoint_binding.cbApplicationDataLength = cbt_size;
                pendpoint_binding.dwApplicationDataOffset = 
                                            sizeof(SEC_CHANNEL_BINDINGS);

                // Then add it to the array of sec buffers accordingly.
                ib[ibd.cBuffers].BufferType = SECBUFFER_CHANNEL_BINDINGS;
                ib[ibd.cBuffers].cbBuffer =
                        pendpoint_binding.cbApplicationDataLength
                        + pendpoint_binding.dwApplicationDataOffset;
          
                sspi_cbt = (char *) moz_xmalloc(ib[ibd.cBuffers].cbBuffer);
                if (!sspi_cbt){
                    return NS_ERROR_OUT_OF_MEMORY;
                }

                // Helper to write in the memory block that stores the CBT
                char* sspi_cbt_ptr = sspi_cbt;
          
                ib[ibd.cBuffers].pvBuffer = sspi_cbt;
                ibd.cBuffers++;

                memcpy(sspi_cbt_ptr, &pendpoint_binding,
                       pendpoint_binding.dwApplicationDataOffset);
                sspi_cbt_ptr += pendpoint_binding.dwApplicationDataOffset;

                memcpy(sspi_cbt_ptr, end_point, end_point_length);
                sspi_cbt_ptr += end_point_length;
          
                // Start hashing. We are always doing SHA256, but depending
                // on the certificate, a different alogirthm might be needed.
                nsAutoCString hashString;

                nsresult rv;
                nsCOMPtr<nsICryptoHash> crypto;
                crypto = do_CreateInstance(NS_CRYPTO_HASH_CONTRACTID, &rv);
                if (NS_SUCCEEDED(rv))
                    rv = crypto->Init(nsICryptoHash::SHA256);
                if (NS_SUCCEEDED(rv))
                    rv = crypto->Update((unsigned char*)mCertDERData, mCertDERLength);
                if (NS_SUCCEEDED(rv))
                    rv = crypto->Finish(false, hashString);
                if (NS_FAILED(rv)) {
                    free(mCertDERData);
                    mCertDERData = nullptr;
                    mCertDERLength = 0;
                    free(sspi_cbt);
                    return rv;
                }
          
                // Once the hash has been computed, we store it in memory right
                // after the Endpoint structure and the "tls-server-end-point:"
                // char array.
                memcpy(sspi_cbt_ptr, hashString.get(), hash_size);
          
                // Free memory used to store the server certificate
                free(mCertDERData);
                mCertDERData = nullptr;
                mCertDERLength = 0;
            } // End of CBT computation.

            // We always need this SECBUFFER.
            ib[ibd.cBuffers].BufferType = SECBUFFER_TOKEN;
            ib[ibd.cBuffers].cbBuffer = inTokenLen;
            ib[ibd.cBuffers].pvBuffer = (void *) inToken;
            ibd.cBuffers++;
            ctxIn = &mCtxt;
        }
    } else { // First time and without a token (no server certificate)
        // We are starting a new authentication sequence.  If we have already 
        // initialized our security context, then we're in trouble because it 
        // means that the first sequence failed.  We need to bail or else we 
        // might end up in an infinite loop.
        if (mCtxt.dwLower || mCtxt.dwUpper || mCertDERData || mCertDERLength) {
            LOG(("Cannot restart authentication sequence!"));
            return NS_ERROR_UNEXPECTED;
        }
        ctxIn = nullptr;
        mIsFirst = false;
    }

    obd.ulVersion = SECBUFFER_VERSION;
    obd.cBuffers = 1;
    obd.pBuffers = &ob;
    ob.BufferType = SECBUFFER_TOKEN;
    ob.cbBuffer = mMaxTokenLen;
    ob.pvBuffer = moz_xmalloc(ob.cbBuffer);
    if (!ob.pvBuffer){
        if (sspi_cbt)
            free(sspi_cbt);
        return NS_ERROR_OUT_OF_MEMORY;
    }
    memset(ob.pvBuffer, 0, ob.cbBuffer);

    NS_ConvertUTF8toUTF16 wSN(mServiceName);
    SEC_WCHAR *sn = (SEC_WCHAR *) wSN.get();

    rc = (sspi->InitializeSecurityContextW)(&mCred,
                                            ctxIn,
                                            sn,
                                            ctxReq,
                                            0,
                                            SECURITY_NATIVE_DREP,
                                            inToken ? &ibd : nullptr,
                                            0,
                                            &mCtxt,
                                            &obd,
                                            &ctxAttr,
                                            &ignored);
    if (rc == SEC_I_CONTINUE_NEEDED || rc == SEC_E_OK) {

        if (rc == SEC_E_OK)
            LOG(("InitializeSecurityContext: succeeded.\n"));
        else
            LOG(("InitializeSecurityContext: continue.\n"));

        if (sspi_cbt)
            free(sspi_cbt);
            
        if (!ob.cbBuffer) {
            free(ob.pvBuffer);
            ob.pvBuffer = nullptr;
        }
        *outToken = ob.pvBuffer;
        *outTokenLen = ob.cbBuffer;

        if (rc == SEC_E_OK)
            return NS_SUCCESS_AUTH_FINISHED;

        return NS_OK;
    }

    LOG(("InitializeSecurityContext failed [rc=%d:%s]\n", rc, MapErrorCode(rc)));
    Reset();
    free(ob.pvBuffer);
    return NS_ERROR_FAILURE;
}

NS_IMETHODIMP
nsAuthSSPI::Unwrap(const void *inToken,
                   uint32_t    inTokenLen,
                   void      **outToken,
                   uint32_t   *outTokenLen)
{
    SECURITY_STATUS rc;
    SecBufferDesc ibd;
    SecBuffer ib[2];

    ibd.cBuffers = 2;
    ibd.pBuffers = ib;
    ibd.ulVersion = SECBUFFER_VERSION; 

    // SSPI Buf
    ib[0].BufferType = SECBUFFER_STREAM;
    ib[0].cbBuffer = inTokenLen;
    ib[0].pvBuffer = moz_xmalloc(ib[0].cbBuffer);
    if (!ib[0].pvBuffer)
        return NS_ERROR_OUT_OF_MEMORY;
    
    memcpy(ib[0].pvBuffer, inToken, inTokenLen);

    // app data
    ib[1].BufferType = SECBUFFER_DATA;
    ib[1].cbBuffer = 0;
    ib[1].pvBuffer = nullptr;

    rc = (sspi->DecryptMessage)(
                                &mCtxt,
                                &ibd,
                                0, // no sequence numbers
                                nullptr
                                );

    if (SEC_SUCCESS(rc)) {
        // check if ib[1].pvBuffer is really just ib[0].pvBuffer, in which
        // case we can let the caller free it. Otherwise, we need to
        // clone it, and free the original
        if (ib[0].pvBuffer == ib[1].pvBuffer) {
            *outToken = ib[1].pvBuffer;
        }
        else {
            *outToken = nsMemory::Clone(ib[1].pvBuffer, ib[1].cbBuffer);
            free(ib[0].pvBuffer);
            if (!*outToken)
                return NS_ERROR_OUT_OF_MEMORY;
        }
        *outTokenLen = ib[1].cbBuffer;
    }
    else
        free(ib[0].pvBuffer);

    if (!SEC_SUCCESS(rc))
        return NS_ERROR_FAILURE;

    return NS_OK;
}

// utility class used to free memory on exit
class secBuffers
{
public:

    SecBuffer ib[3];

    secBuffers() { memset(&ib, 0, sizeof(ib)); }

    ~secBuffers() 
    {
        if (ib[0].pvBuffer)
            free(ib[0].pvBuffer);

        if (ib[1].pvBuffer)
            free(ib[1].pvBuffer);

        if (ib[2].pvBuffer)
            free(ib[2].pvBuffer);
    }
};

NS_IMETHODIMP
nsAuthSSPI::Wrap(const void *inToken,
                 uint32_t    inTokenLen,
                 bool        confidential,
                 void      **outToken,
                 uint32_t   *outTokenLen)
{
    SECURITY_STATUS rc;

    SecBufferDesc ibd;
    secBuffers bufs;
    SecPkgContext_Sizes sizes;

    rc = (sspi->QueryContextAttributesW)(
         &mCtxt,
         SECPKG_ATTR_SIZES,
         &sizes);

    if (!SEC_SUCCESS(rc))  
        return NS_ERROR_FAILURE;
    
    ibd.cBuffers = 3;
    ibd.pBuffers = bufs.ib;
    ibd.ulVersion = SECBUFFER_VERSION;
    
    // SSPI
    bufs.ib[0].cbBuffer = sizes.cbSecurityTrailer;
    bufs.ib[0].BufferType = SECBUFFER_TOKEN;
    bufs.ib[0].pvBuffer = moz_xmalloc(sizes.cbSecurityTrailer);

    if (!bufs.ib[0].pvBuffer)
        return NS_ERROR_OUT_OF_MEMORY;

    // APP Data
    bufs.ib[1].BufferType = SECBUFFER_DATA;
    bufs.ib[1].pvBuffer = moz_xmalloc(inTokenLen);
    bufs.ib[1].cbBuffer = inTokenLen;
    
    if (!bufs.ib[1].pvBuffer)
        return NS_ERROR_OUT_OF_MEMORY;

    memcpy(bufs.ib[1].pvBuffer, inToken, inTokenLen);

    // SSPI
    bufs.ib[2].BufferType = SECBUFFER_PADDING;
    bufs.ib[2].cbBuffer = sizes.cbBlockSize;
    bufs.ib[2].pvBuffer = moz_xmalloc(bufs.ib[2].cbBuffer);

    if (!bufs.ib[2].pvBuffer)
        return NS_ERROR_OUT_OF_MEMORY;

    rc = (sspi->EncryptMessage)(&mCtxt,
          confidential ? 0 : KERB_WRAP_NO_ENCRYPT,
         &ibd, 0);

    if (SEC_SUCCESS(rc)) {
        int len  = bufs.ib[0].cbBuffer + bufs.ib[1].cbBuffer + bufs.ib[2].cbBuffer;
        char *p = (char *) moz_xmalloc(len);

        if (!p)
            return NS_ERROR_OUT_OF_MEMORY;
				
        *outToken = (void *) p;
        *outTokenLen = len;

        memcpy(p, bufs.ib[0].pvBuffer, bufs.ib[0].cbBuffer);
        p += bufs.ib[0].cbBuffer;

        memcpy(p,bufs.ib[1].pvBuffer, bufs.ib[1].cbBuffer);
        p += bufs.ib[1].cbBuffer;

        memcpy(p,bufs.ib[2].pvBuffer, bufs.ib[2].cbBuffer);
        
        return NS_OK;
    }

    return NS_ERROR_FAILURE;
}