/* Copyright 2003-2006, Voltage Security, all rights reserved.
 */
#include "vibe.h"
#include "environment.h"
#include "base.h"
#include "libctx.h"
#include "algobj.h"
#include "sign.h"
#include "oidlist.h"
#include "algid.h"
#include "errorctx.h"

int VtDerCoderDSAwSHA1 (
   VtDerCoderInfo *coderInfo,
   Pointer object,
   unsigned int flag
   )
{
  int status;
  unsigned int bufferSize;
  VoltLibCtx *libCtx;
  VoltAlgorithmObject **obj = (VoltAlgorithmObject **)0;
  VoltSignClassCtx *signCtx;
  VoltDerCoderEncodeData *encodeData = &(coderInfo->info.encodeData);
  VoltDerCoderGetAlgData *getAlgData = &(coderInfo->info.getAlgData);
  VoltDerCoderDecodeData *decodeData = &(coderInfo->info.decodeData);
  Asn1AlgorithmId *algId;
  unsigned char dsaAlgID[VoltDsaSHA1AlgIdBytesLen] =
    { VoltDsaSHA1AlgIdBytes };
  /* Alternate OID to read (never produce). See comments in DECODE case.
   */
  unsigned char altDsaSHA1Oid[VoltDsaKeyOidBytesLen] = { VoltDsaKeyOidBytes };
  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 DSA sign 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;

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

      /* The info should be NULL.
       */
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_NON_NULL_ARG;
      if (encodeData->info != (Pointer)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) = VoltDsaSHA1AlgIdBytesLen;
      if (bufferSize < VoltDsaSHA1AlgIdBytesLen)
        break;

      /* There's only one possible DSA alg ID.
       */
      libCtx = encodeData->libCtx;
      Z2Memcpy (encodeData->encoding, dsaAlgID, VoltDsaSHA1AlgIdBytesLen);
      status = 0;
      break;

    case VOLT_DER_TYPE_DECODE_FLAG:
      /* If the flag is decode, set the object to perform DSA with SHA-1.
       */

      /* Check the args, the type should be VOLT_DER_TYPE_ALG_ID_FLAG.
       */
      VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_UNKNOWN_BER;
      if (decodeData->type != VOLT_DER_TYPE_ALG_ID_FLAG)
        break;

      VOLT_SET_FNCT_LINE (fnctLine)
      if (object == (Pointer)0)
        break;

      obj = (VoltAlgorithmObject **)object;
      VOLT_SET_FNCT_LINE (fnctLine)
      if (*obj == (VoltAlgorithmObject *)0)
        break;

      /* Make sure this is the algId for DSA.
       */
      algId = (Asn1AlgorithmId *)(decodeData->asn1Object);
      libCtx = (VoltLibCtx *)((*obj)->voltObject.libraryCtx);

      if (algId->oid->base.length == VoltDsaSHA1OidBytesLen)
      {
        if (Z2Memcmp (
          algId->oid->base.data, dsaAlgID + VoltDsaSHA1AlgIdOidOffset,
          VoltDsaSHA1OidBytesLen) == 0)
          status = 0;
      }

      /* If the alg ID is not DSA with SHA-1, it might be that the alg
       * ID contains the OID for DSA key. Although that is not the
       * correct OID, standards committees require reading it as DSA
       * With SHA-1 when determining a signature alg because so many
       * clients have made that mistake. If we are at this point in
       * the code, the info's type is VOLT_DER_TYPE_ALG_ID_FLAG, so we
       * know we're not trying to read a key.
       */
      if (status != 0)
      {
        if (algId->oid->base.length != VoltDsaKeyOidBytesLen)
          break;

        if (Z2Memcmp (
          algId->oid->base.data, altDsaSHA1Oid, VoltDsaKeyOidBytesLen) != 0)
          break;
      }

      VtDestroyAlgorithmObject((VtAlgorithmObject *)object);

      /* Use bufferSize as a variable to pass in the signature format.
       */
      VOLT_SET_ERROR_TYPE (errorType, 0)
      VOLT_SET_FNCT_LINE (fnctLine)
      bufferSize = VT_DSA_SIGNATURE_DER_ENCODED;
      status = VtCreateAlgorithmObject (
        (VtLibCtx)libCtx, VtAlgorithmImplDSASignVerify, (Pointer)&bufferSize, 
        (VtAlgorithmObject *)object);
      if (status != 0)
        break;

      obj = (VoltAlgorithmObject **)object;

      /* Set the ALG_ID bit in the classCtx->algorithm field. Also, set
       * the classCtx->digestAlg field, the digest algorithm to use is
       * fixed.
       */
      signCtx =
        (VoltSignClassCtx *)(((VoltAlgorithmObject *)(*obj))->classCtx);
      signCtx->algorithm |= VOLT_SIGNATURE_ALG_ID;
      signCtx->digestAlg = VT_DIGEST_ALG_SHA1;

      break;

    case VOLT_DER_TYPE_GET_ALG_FLAG:
      /* If the flag is get alg, check the input to see if it's the
       * DSA 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 != VoltDsaSHA1OidBytesLen)
        break;

      libCtx = getAlgData->libCtx;
      if (Z2Memcmp (
        getAlgData->oid, dsaAlgID + VoltDsaSHA1AlgIdOidOffset,
        VoltDsaSHA1OidBytesLen) != 0)
        break;

      /* The OID matches, the algorithm is DSA with SHA-1
       */
      *(getAlgData->algorithm) = VT_ALG_ID_DSA_SHA1_SIGN;
      getAlgData->DigestImpl = VtAlgorithmImplSHA1;
      getAlgData->SymKeyParam = (VtKeyParam *)0;

      status = 0;
  }

  VOLT_LOG_ERROR_INFO_COMPARE (
    status, 0, object, status, 0, errorType,
    (char *)0, "VtDerCoderDSAwSHA1", fnctLine, (char *)0)

  return (status);
}