/* Copyright 2003-2006, Voltage Security, all rights reserved.
 */
#include "vibecrypto.h"
#include "environment.h"
#include "base.h"
#include "libctx.h"
#include "algobj.h"
#include "cipher.h"
#include "block.h"
#include "ofb.h"
#include "errorctx.h"

/* This routine does the work. It allocates and fills in the contexts.
 * @param obj The algorithm object to set.
 * @param cipherCtx The Cipher Class context to set.
 * @param blockCtx The BlockCipher context to set.
 * @param iv The item containing the init vector.
 * @return an int, 0 if the function completed successfully or a
 * non-zero error code.
 */
static int VOLT_CALLING_CONV SetObjectOFB VOLT_PROTO_LIST ((
   VoltAlgorithmObject *obj,
   VoltCipherClassCtx *cipherCtx,
   VoltBlockCipherCtx *blockCtx,
   VtItem *iv
));

int VtFeedbackOFB (
   VtAlgorithmObject object,
   VtFeedbackInfo *feedInfo,
   unsigned int flag
   )
{
  int status;
  unsigned int blockSize;
  VoltAlgorithmObject *obj = (VoltAlgorithmObject *)object;
  VtItem *iv = (VtItem *)(feedInfo->info);
  VoltCipherClassCtx *cipherCtx;
  VoltBlockCipherCtx *blockCtx;
  VOLT_DECLARE_ERROR_TYPE (errorType)
  VOLT_DECLARE_FNCT_LINE (fnctLine)

  do
  {
    /* Check the flag, it should be VOLT_FEEDBACK_SET_TYPE_FLAG.
     */
    VOLT_SET_ERROR_TYPE (errorType, VT_ERROR_TYPE_PRIMARY)
    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_INVALID_TYPE;
    if (flag != VOLT_FEEDBACK_SET_TYPE_FLAG)
      break;

    /* The associated info should be a pointer to a VoltageOFBInfo
     * struct.
     */
    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_INVALID_ASSOCIATED_INFO;
    if (feedInfo->info == (Pointer)0)
      break;

    /* Check the class of the object. It should be
     * VOLT_CLASS_BLOCK_CIPHER.
     */
    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_INVALID_TYPE;
    if (obj->algClass != VOLT_CLASS_BLOCK_CIPHER)
      break;

    /* We have a block cipher object, which means we have a CipherCtx
     * and a BlockCtx.
     */
    cipherCtx = (VoltCipherClassCtx *)(obj->classCtx);
    blockCtx = (VoltBlockCipherCtx *)(cipherCtx->localCipherCtx);

    /* Make sure the setState in the CipherCtx is correct.
     */
    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_INVALID_SET;
    if (cipherCtx->setState != VOLT_BLOCK_SET_STATE_ALG)
      break;

    /* Make sure there's data and that it is blockSize bytes long.
     */
    VOLT_SET_FNCT_LINE (fnctLine)
    blockSize = cipherCtx->plainBlockSize;
    if ( (blockSize < 2) || (blockSize != cipherCtx->cipherBlockSize) )
      break;

    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_INVALID_ASSOCIATED_INFO;
    if ( (iv->data == (unsigned char *)0) || (iv->len != blockSize) )
      break;

    VOLT_SET_ERROR_TYPE (errorType, 0)
    VOLT_SET_FNCT_LINE (fnctLine)
    status = SetObjectOFB (obj, cipherCtx, blockCtx, iv);

  } while (0);

  VOLT_LOG_ERROR_COMPARE (
    status, obj->voltObject.libraryCtx, status, errorType, fnctLine,
    "VtFeedbackOFB", (char *)0)

  return (status);
}

static int SetObjectOFB (
   VoltAlgorithmObject *obj,
   VoltCipherClassCtx *cipherCtx,
   VoltBlockCipherCtx *blockCtx,
   VtItem *iv
   )
{
  int status;
  unsigned int blockSize, bufferSize, offset;
#if VOLT_ALIGNMENT != 1
  unsigned int pad;
#endif
  unsigned char *buffer = (unsigned char *)0;
  VoltLibCtx *libCtx = (VoltLibCtx *)(obj->voltObject.libraryCtx);
  VoltOFBCtx *ofbCtx = (VoltOFBCtx *)0;
  VOLT_DECLARE_FNCT_LINE (fnctLine)

  do
  {
    /* Allocate enough space for an OFB Ctx and two blockSize buffers.
     * Because the buffers will be pointers to byte arrays, we should
     * not have to worry about alignment. However, we may want to
     * dereference the pointer to the xorVector as a UInt32 or UInt64,
     * so make sure that buffer is aligned.
     */
    VOLT_SET_FNCT_LINE (fnctLine)
    status = VT_ERROR_MEMORY;
    blockSize = iv->len;
    bufferSize = sizeof (VoltOFBCtx) + (2 * blockSize);
#if VOLT_ALIGNMENT != 1
    /* If the alignment is 1, there's no need to pad. If not, compute
     * the pad length.
     */
    VOLT_COMPUTE_ALIGN_PAD (VOLT_ALIGNMENT, sizeof (VoltOFBCtx), pad)
    bufferSize += pad;
#endif
    buffer = (unsigned char *)Z2Malloc (bufferSize, VOLT_MEMORY_SENSITIVE);
    if (buffer == (unsigned char *)0)
      break;
    Z2Memset (buffer, 0, bufferSize);

    /* Locate the pointers.
     */
    ofbCtx = (VoltOFBCtx *)buffer;
    offset = sizeof (VoltOFBCtx);
#if VOLT_ALIGNMENT != 1
    offset += pad;
#endif
    ofbCtx->feedCtx.xorVector = buffer + offset;
    offset += blockSize;
    ofbCtx->feedCtx.initVector = buffer + offset;

    /* Populate the contexts.
     */
    Z2Memcpy (ofbCtx->feedCtx.initVector, iv->data, iv->len);
    ofbCtx->feedCtx.blockSize = blockSize;
    ofbCtx->AlgEncryptInit = cipherCtx->EncryptInit;
    ofbCtx->AlgEncryptUpdate = cipherCtx->EncryptUpdate;
    blockCtx->feedbackCtx = (Pointer)ofbCtx;
    blockCtx->FeedbackCtxDestroy = VoltSimpleCtxDestroy;

    cipherCtx->EncryptInit = OFBEncryptInit;
    cipherCtx->EncryptUpdate = OFBEncryptUpdate;
    cipherCtx->DecryptInit = OFBEncryptInit;
    cipherCtx->DecryptUpdate = OFBEncryptUpdate;
    cipherCtx->plainBlockSize = 1;
    cipherCtx->cipherBlockSize = 1;
    cipherCtx->GetOutputSize = VoltStreamEncDecGetOutputSize;
    cipherCtx->setState = VOLT_BLOCK_SET_STATE_FEED;

    obj->subAlg2 = VOLT_SUB_ALG_OFB;

    status = 0;

  } while (0);

  /* If everything worked, return 0.
   */
  if (status == 0)
    return (0);

  /* If something went wrong, destroy anything we created and indicate
   * that this object is not usable.
   */
  if (buffer != (unsigned char *)0)
    Z2Free (buffer);

  obj->state = VOLT_STATE_ERROR;

  VOLT_LOG_ERROR (
    obj->voltObject.libraryCtx, status, VT_ERROR_TYPE_PRIMARY, fnctLine,
    "SetObjectOFB", (char *)0)

  return (status);
}