/* Copyright 2006, Voltage Security, all rights reserved.
 */
#include "vibe.h"
#include "environment.h"
#include "base.h"
#include "libctx.h"
#include "algobj.h"
#include "oidlist.h"
#include "algid.h"
#include "errorctx.h"

int VtDerCoderSHA256 (
   VtDerCoderInfo *coderInfo,
   Pointer object,
   unsigned int flag
   )
{
  int status;
  unsigned int bufferSize;
  VoltAlgorithmObject **obj = (VoltAlgorithmObject **) 0;
  VoltDerCoderEncodeData *encodeData = &(coderInfo->info.encodeData);
  VoltDerCoderGetAlgData *getAlgData = &(coderInfo->info.getAlgData);
  VoltDerCoderDecodeData *decodeData = &(coderInfo->info.decodeData);
  Asn1AlgorithmId *algId;
  VoltLibCtx *libCtx;
  unsigned char sha256AlgID[VoltSHA256AlgIdBytesLen] = { VoltSHA256AlgIdBytes };
  VOLT_DECLARE_ERROR_TYPE (errorType)
  VOLT_DECLARE_FNCT_LINE (fnctLine)

  switch (flag)
  {
    default:
      VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_INVALID_TYPE;
      break;

    case VOLT_DER_TYPE_ENCODE_FLAG:
      /* If the flag is ENCODE, return the SHA-256 algID.
       */

      /* Check the args.
       */
      VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NON_NULL_ARG;
      if (object != (Pointer)0)
        break;

      /* The SHA-256 info should be NULL.
       */
      VOLT_SET_FNCT_LINE (fnctLine)
      if (encodeData->info != (Pointer)0)
        break;

      /* We need a place to drop the length.
       */
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NULL_ARG;
      if (encodeData->encodingLen == (unsigned int *)0)
        break;

      bufferSize = encodeData->bufferSize;
      if (encodeData->encoding == (unsigned char *)0)
        bufferSize = 0;

      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_BUFFER_TOO_SMALL;
      *(encodeData->encodingLen) = VoltSHA256AlgIdBytesLen;
      if (bufferSize < VoltSHA256AlgIdBytesLen)
        break;

      /* There's only one possible SHA-256 alg ID.
       */
      libCtx = encodeData->libCtx;
      Z2Memcpy (encodeData->encoding, sha256AlgID, VoltSHA256AlgIdBytesLen);

      status = 0;
      break;

    case VOLT_DER_TYPE_DECODE_FLAG:
      /* If the flag is decode, set the object to perform SHA-256.
       */
      VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NULL_ARG;
      if (object == (Pointer)0)
        break;

      obj = (VoltAlgorithmObject **) object;

      /* Check the args, the info should be a pointer to a
       * VoltDerCoderDecodeData struct, with the type
       * VOLT_DER_TYPE_ALG_ID_FLAG.
       */
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_UNKNOWN_BER;
      if (decodeData->type != VOLT_DER_TYPE_ALG_ID_FLAG)
        break;

      /* Make sure this is the algId for SHA-256.
       */
      VOLT_SET_FNCT_LINE (fnctLine)
      algId = (Asn1AlgorithmId *)(decodeData->asn1Object);
      if (algId->oid->base.length != VoltSHA256OidBytesLen)
        break;

      libCtx = (VoltLibCtx *)((*obj)->voltObject.libraryCtx);

      VOLT_SET_FNCT_LINE (fnctLine)
      if (Z2Memcmp (
          algId->oid->base.data, sha256AlgID + VoltSHA256AlgIdOidOffset,
          VoltSHA256OidBytesLen) != 0)
        break;

      VtDestroyAlgorithmObject ((VtAlgorithmObject *)object);

      VOLT_SET_ERROR_TYPE (errorType, 0)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VtCreateAlgorithmObject (
        libCtx, VtAlgorithmImplSHA256, (Pointer)0,
        (VtAlgorithmObject *)object);

      break;

    case VOLT_DER_TYPE_GET_ALG_FLAG:
      /* If the flag is get alg, check the input to see if it's the
       * SHA-256 OID.
       */

      /* Check the args.
       */
      VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NON_NULL_ARG;
      if (object != (Pointer)0)
        break;

      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NULL_ARG;
      if ( (getAlgData->algorithm == (unsigned int *)0) ||
           (getAlgData->oid == (unsigned char *)0) )
        break;

      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_UNKNOWN_BER;
      if (getAlgData->oidLen != VoltSHA256OidBytesLen)
        break;

      libCtx = getAlgData->libCtx;

      VOLT_SET_FNCT_LINE (fnctLine)
      if (Z2Memcmp (
        getAlgData->oid, sha256AlgID + VoltSHA256AlgIdOidOffset,
        VoltSHA256OidBytesLen) != 0)
        break;

      /* The OID matches, the algorithm is SHA-256.
       */
      *(getAlgData->algorithm) = VT_ALG_ID_SHA256;
      getAlgData->SymKeyParam = (VtKeyParam *)0;
      getAlgData->DigestImpl = VtAlgorithmImplSHA256;

      status = 0;
  }

  VOLT_LOG_ERROR_INFO_COMPARE (
    status, 0, object, status, 0, errorType,
    (char *)0, "VtDerCoderSHA256", fnctLine, (char *)0)

  return (status);
}