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      1 // Copyright 2014 PDFium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
      6 
      7 #include "core/fxcrt/cfx_checksumcontext.h"
      8 
      9 #include "core/fdrm/crypto/fx_crypt.h"
     10 #include "core/fxcrt/fx_stream.h"
     11 #include "core/fxcrt/xml/cfx_saxreaderhandler.h"
     12 #include "third_party/base/ptr_util.h"
     13 
     14 namespace {
     15 
     16 struct FX_BASE64DATA {
     17   uint32_t data1 : 2;
     18   uint32_t data2 : 6;
     19   uint32_t data3 : 4;
     20   uint32_t data4 : 4;
     21   uint32_t data5 : 6;
     22   uint32_t data6 : 2;
     23   uint32_t data7 : 8;
     24 };
     25 
     26 const char g_FXBase64EncoderMap[64] = {
     27     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
     28     'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
     29     'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
     30     'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
     31     '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
     32 };
     33 
     34 void Base64EncodePiece(const FX_BASE64DATA& src, int32_t iBytes, char dst[4]) {
     35   dst[0] = g_FXBase64EncoderMap[src.data2];
     36   uint32_t b = src.data1 << 4;
     37   if (iBytes > 1) {
     38     b |= src.data4;
     39   }
     40   dst[1] = g_FXBase64EncoderMap[b];
     41   if (iBytes > 1) {
     42     b = src.data3 << 2;
     43     if (iBytes > 2) {
     44       b |= src.data6;
     45     }
     46     dst[2] = g_FXBase64EncoderMap[b];
     47     if (iBytes > 2) {
     48       dst[3] = g_FXBase64EncoderMap[src.data5];
     49     } else {
     50       dst[3] = '=';
     51     }
     52   } else {
     53     dst[2] = dst[3] = '=';
     54   }
     55 }
     56 
     57 int32_t Base64EncodeA(const uint8_t* pSrc, int32_t iSrcLen, char* pDst) {
     58   ASSERT(pSrc);
     59   if (iSrcLen < 1) {
     60     return 0;
     61   }
     62   if (!pDst) {
     63     int32_t iDstLen = iSrcLen / 3 * 4;
     64     if ((iSrcLen % 3) != 0) {
     65       iDstLen += 4;
     66     }
     67     return iDstLen;
     68   }
     69   FX_BASE64DATA srcData;
     70   int32_t iBytes = 3;
     71   char* pDstEnd = pDst;
     72   while (iSrcLen > 0) {
     73     if (iSrcLen > 2) {
     74       ((uint8_t*)&srcData)[0] = *pSrc++;
     75       ((uint8_t*)&srcData)[1] = *pSrc++;
     76       ((uint8_t*)&srcData)[2] = *pSrc++;
     77       iSrcLen -= 3;
     78     } else {
     79       *((uint32_t*)&srcData) = 0;
     80       ((uint8_t*)&srcData)[0] = *pSrc++;
     81       if (iSrcLen > 1) {
     82         ((uint8_t*)&srcData)[1] = *pSrc++;
     83       }
     84       iBytes = iSrcLen;
     85       iSrcLen = 0;
     86     }
     87     Base64EncodePiece(srcData, iBytes, pDstEnd);
     88     pDstEnd += 4;
     89   }
     90   return pDstEnd - pDst;
     91 }
     92 
     93 }  // namespace
     94 
     95 CFX_ChecksumContext::CFX_ChecksumContext() {}
     96 
     97 CFX_ChecksumContext::~CFX_ChecksumContext() {}
     98 
     99 void CFX_ChecksumContext::StartChecksum() {
    100   FinishChecksum();
    101   m_pByteContext = pdfium::MakeUnique<CRYPT_sha1_context>();
    102   CRYPT_SHA1Start(m_pByteContext.get());
    103   m_bsChecksum.clear();
    104   m_pSAXReader = pdfium::MakeUnique<CFX_SAXReader>();
    105 }
    106 
    107 bool CFX_ChecksumContext::UpdateChecksum(
    108     const RetainPtr<IFX_SeekableReadStream>& pSrcFile,
    109     FX_FILESIZE offset,
    110     size_t size) {
    111   if (!m_pSAXReader || !pSrcFile)
    112     return false;
    113 
    114   if (size < 1)
    115     size = pSrcFile->GetSize();
    116 
    117   CFX_SAXReaderHandler handler(this);
    118   m_pSAXReader->SetHandler(&handler);
    119   if (m_pSAXReader->StartParse(
    120           pSrcFile, (uint32_t)offset, (uint32_t)size,
    121           CFX_SaxParseMode_NotSkipSpace | CFX_SaxParseMode_NotConvert_amp |
    122               CFX_SaxParseMode_NotConvert_lt | CFX_SaxParseMode_NotConvert_gt |
    123               CFX_SaxParseMode_NotConvert_sharp) < 0) {
    124     return false;
    125   }
    126   return m_pSAXReader->ContinueParse() > 99;
    127 }
    128 
    129 void CFX_ChecksumContext::FinishChecksum() {
    130   m_pSAXReader.reset();
    131   if (m_pByteContext) {
    132     uint8_t digest[20];
    133     memset(digest, 0, 20);
    134     CRYPT_SHA1Finish(m_pByteContext.get(), digest);
    135     int32_t nLen = Base64EncodeA(digest, 20, nullptr);
    136     char* pBuffer = m_bsChecksum.GetBuffer(nLen);
    137     Base64EncodeA(digest, 20, pBuffer);
    138     m_bsChecksum.ReleaseBuffer(nLen);
    139     m_pByteContext.reset();
    140   }
    141 }
    142 
    143 ByteString CFX_ChecksumContext::GetChecksum() const {
    144   return m_bsChecksum;
    145 }
    146 
    147 void CFX_ChecksumContext::Update(const ByteStringView& bsText) {
    148   if (!m_pByteContext)
    149     return;
    150 
    151   CRYPT_SHA1Update(m_pByteContext.get(), bsText.raw_str(), bsText.GetLength());
    152 }
    153