/*
 * s3fs - FUSE-based file system backed by Amazon S3
 *
 * Copyright 2007-2008 Randy Rizun <rrizun@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <nss.h>
#include <pk11pub.h>
#include <hasht.h>
#include <prinit.h>
#include <string>
#include <map>

#include "common.h"
#include "s3fs_auth.h"

using namespace std;

//-------------------------------------------------------------------
// Utility Function for version
//-------------------------------------------------------------------
const char* s3fs_crypt_lib_name(void)
{
  static const char version[] = "NSS";

  return version;
}

//-------------------------------------------------------------------
// Utility Function for global init
//-------------------------------------------------------------------
bool s3fs_init_global_ssl(void)
{
  NSS_Init(NULL);
  NSS_NoDB_Init(NULL);
  return true;
}

bool s3fs_destroy_global_ssl(void)
{
  NSS_Shutdown();
  PL_ArenaFinish();
  PR_Cleanup();
  return true;
}

//-------------------------------------------------------------------
// Utility Function for crypt lock
//-------------------------------------------------------------------
bool s3fs_init_crypt_mutex(void)
{
  return true;
}

bool s3fs_destroy_crypt_mutex(void)
{
  return true;
}

//-------------------------------------------------------------------
// Utility Function for HMAC
//-------------------------------------------------------------------
bool s3fs_HMAC(const void* key, size_t keylen, const unsigned char* data, size_t datalen, unsigned char** digest, unsigned int* digestlen)
{
  if(!key || 0 >= keylen || !data || 0 >= datalen || !digest || !digestlen){
    return false;
  }

  PK11SlotInfo* Slot;
  PK11SymKey*   pKey;
  PK11Context*  Context;
  SECStatus     SecStatus;
  unsigned char tmpdigest[64];
  SECItem       KeySecItem   = {siBuffer, reinterpret_cast<unsigned char*>(const_cast<void*>(key)), keylen};
  SECItem       NullSecItem  = {siBuffer, NULL, 0};

  if(NULL == (Slot = PK11_GetInternalKeySlot())){
    return false;
  }
  if(NULL == (pKey = PK11_ImportSymKey(Slot, CKM_SHA_1_HMAC, PK11_OriginUnwrap, CKA_SIGN, &KeySecItem, NULL))){
    PK11_FreeSlot(Slot);
    return false;
  }
  if(NULL == (Context = PK11_CreateContextBySymKey(CKM_SHA_1_HMAC, CKA_SIGN, pKey, &NullSecItem))){
    PK11_FreeSymKey(pKey);
    PK11_FreeSlot(Slot);
    return false;
  }

  *digestlen = 0;
  if(SECSuccess != (SecStatus = PK11_DigestBegin(Context)) ||
     SECSuccess != (SecStatus = PK11_DigestOp(Context, data, datalen)) ||
     SECSuccess != (SecStatus = PK11_DigestFinal(Context, tmpdigest, digestlen, sizeof(tmpdigest))) )
  {
    PK11_DestroyContext(Context, PR_TRUE);
    PK11_FreeSymKey(pKey);
    PK11_FreeSlot(Slot);
    return false;
  }
  PK11_DestroyContext(Context, PR_TRUE);
  PK11_FreeSymKey(pKey);
  PK11_FreeSlot(Slot);

  if(NULL == (*digest = (unsigned char*)malloc(*digestlen))){
    return false;
  }
  memcpy(*digest, tmpdigest, *digestlen);

  return true;
}

//-------------------------------------------------------------------
// Utility Function for MD5
//-------------------------------------------------------------------
size_t get_md5_digest_length(void)
{
  return MD5_LENGTH;
}

unsigned char* s3fs_md5hexsum(int fd, off_t start, ssize_t size)
{
  PK11Context*	 md5ctx;
  unsigned char  buf[512];
  ssize_t        bytes;
  unsigned char* result;
  unsigned int   md5outlen;

  if(-1 == size){
    struct stat st;
    if(-1 == fstat(fd, &st)){
      return NULL;
    }
    size = static_cast<ssize_t>(st.st_size);
  }

  // seek to top of file.
  if(-1 == lseek(fd, start, SEEK_SET)){
    return NULL;
  }

  memset(buf, 0, 512);
  md5ctx = PK11_CreateDigestContext(SEC_OID_MD5);

  for(ssize_t total = 0; total < size; total += bytes){
    bytes = 512 < (size - total) ? 512 : (size - total);
    bytes = read(fd, buf, bytes);
    if(0 == bytes){
      // end of file
      break;
    }else if(-1 == bytes){
      // error
      DPRNNN("file read error(%d)", errno);
      return NULL;
    }
    PK11_DigestOp(md5ctx, buf, bytes);
    memset(buf, 0, 512);
  }
  if(NULL == (result = (unsigned char*)malloc(get_md5_digest_length()))){
    PK11_DestroyContext(md5ctx, PR_TRUE);
    return NULL;
  }
  PK11_DigestFinal(md5ctx, result, &md5outlen, get_md5_digest_length());
  PK11_DestroyContext(md5ctx, PR_TRUE);

  if(-1 == lseek(fd, start, SEEK_SET)){
    free(result);
    return NULL;
  }

  return result;
}

/// END