fpdfsdk/fpdfattachment.cpp

// Copyright 2017 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "public/fpdf_attachment.h"

#include <memory>
#include <utility>

#include "core/fdrm/crypto/fx_crypt.h"
#include "core/fpdfapi/page/cpdf_streamparser.h"
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_document.h"
#include "core/fpdfapi/parser/cpdf_name.h"
#include "core/fpdfapi/parser/cpdf_number.h"
#include "core/fpdfapi/parser/cpdf_reference.h"
#include "core/fpdfapi/parser/cpdf_string.h"
#include "core/fpdfapi/parser/fpdf_parser_decode.h"
#include "core/fpdfdoc/cpdf_filespec.h"
#include "core/fpdfdoc/cpdf_nametree.h"
#include "core/fxcrt/cfx_datetime.h"
#include "core/fxcrt/fx_extension.h"
#include "fpdfsdk/fsdk_define.h"

namespace {

CFX_ByteString CFXByteStringHexDecode(const CFX_ByteString& bsHex) {
  uint8_t* result = nullptr;
  uint32_t size = 0;
  HexDecode(bsHex.raw_str(), bsHex.GetLength(), &result, &size);
  CFX_ByteString bsDecoded(result, size);
  FX_Free(result);
  return bsDecoded;
}

CFX_ByteString GenerateMD5Base16(const void* contents,
                                 const unsigned long len) {
  uint8_t digest[16];
  CRYPT_MD5Generate(reinterpret_cast<const uint8_t*>(contents), len, digest);
  char buf[32];
  for (int i = 0; i < 16; ++i)
    FXSYS_IntToTwoHexChars(digest[i], &buf[i * 2]);

  return CFX_ByteString(buf, 32);
}

}  // namespace

DLLEXPORT int STDCALL FPDFDoc_GetAttachmentCount(FPDF_DOCUMENT document) {
  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
  if (!pDoc)
    return 0;

  return CPDF_NameTree(pDoc, "EmbeddedFiles").GetCount();
}

DLLEXPORT FPDF_ATTACHMENT STDCALL FPDFDoc_AddAttachment(FPDF_DOCUMENT document,
                                                        FPDF_WIDESTRING name) {
  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
  CFX_WideString wsName =
      CFX_WideString::FromUTF16LE(name, CFX_WideString::WStringLength(name));
  if (!pDoc || wsName.IsEmpty())
    return nullptr;

  CPDF_Dictionary* pRoot = pDoc->GetRoot();
  if (!pRoot)
    return nullptr;

  // Retrieve the document's Names dictionary; create it if missing.
  CPDF_Dictionary* pNames = pRoot->GetDictFor("Names");
  if (!pNames) {
    pNames = pDoc->NewIndirect<CPDF_Dictionary>();
    pRoot->SetNewFor<CPDF_Reference>("Names", pDoc, pNames->GetObjNum());
  }

  // Create the EmbeddedFiles dictionary if missing.
  if (!pNames->GetDictFor("EmbeddedFiles")) {
    CPDF_Dictionary* pFiles = pDoc->NewIndirect<CPDF_Dictionary>();
    pFiles->SetNewFor<CPDF_Array>("Names");
    pNames->SetNewFor<CPDF_Reference>("EmbeddedFiles", pDoc,
                                      pFiles->GetObjNum());
  }

  // Set up the basic entries in the filespec dictionary.
  CPDF_Dictionary* pFile = pDoc->NewIndirect<CPDF_Dictionary>();
  pFile->SetNewFor<CPDF_Name>("Type", "Filespec");
  pFile->SetNewFor<CPDF_String>("UF", wsName);
  pFile->SetNewFor<CPDF_String>("F", wsName);

  // Add the new attachment name and filespec into the document's EmbeddedFiles.
  CPDF_NameTree nameTree(pDoc, "EmbeddedFiles");
  if (!nameTree.AddValueAndName(
          pdfium::MakeUnique<CPDF_Reference>(pDoc, pFile->GetObjNum()),
          wsName)) {
    return nullptr;
  }

  return pFile;
}

DLLEXPORT FPDF_ATTACHMENT STDCALL FPDFDoc_GetAttachment(FPDF_DOCUMENT document,
                                                        int index) {
  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
  if (!pDoc || index < 0)
    return nullptr;

  CPDF_NameTree nameTree(pDoc, "EmbeddedFiles");
  if (static_cast<size_t>(index) >= nameTree.GetCount())
    return nullptr;

  CFX_WideString csName;
  return nameTree.LookupValueAndName(index, &csName);
}

DLLEXPORT FPDF_BOOL STDCALL FPDFDoc_DeleteAttachment(FPDF_DOCUMENT document,
                                                     int index) {
  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
  if (!pDoc || index < 0)
    return false;

  CPDF_NameTree nameTree(pDoc, "EmbeddedFiles");
  if (static_cast<size_t>(index) >= nameTree.GetCount())
    return false;

  return nameTree.DeleteValueAndName(index);
}

DLLEXPORT unsigned long STDCALL
FPDFAttachment_GetName(FPDF_ATTACHMENT attachment,
                       void* buffer,
                       unsigned long buflen) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  if (!pFile)
    return 0;

  return Utf16EncodeMaybeCopyAndReturnLength(CPDF_FileSpec(pFile).GetFileName(),
                                             buffer, buflen);
}

DLLEXPORT FPDF_BOOL STDCALL FPDFAttachment_HasKey(FPDF_ATTACHMENT attachment,
                                                  FPDF_WIDESTRING key) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  if (!pFile)
    return 0;

  CPDF_Dictionary* pParamsDict = CPDF_FileSpec(pFile).GetParamsDict();
  if (!pParamsDict)
    return 0;

  return pParamsDict->KeyExist(CFXByteStringFromFPDFWideString(key));
}

DLLEXPORT FPDF_OBJECT_TYPE STDCALL
FPDFAttachment_GetValueType(FPDF_ATTACHMENT attachment, FPDF_WIDESTRING key) {
  if (!FPDFAttachment_HasKey(attachment, key))
    return FPDF_OBJECT_UNKNOWN;

  CPDF_Object* pObj = CPDF_FileSpec(CPDFObjectFromFPDFAttachment(attachment))
                          .GetParamsDict()
                          ->GetObjectFor(CFXByteStringFromFPDFWideString(key));
  if (!pObj)
    return FPDF_OBJECT_UNKNOWN;

  return pObj->GetType();
}

DLLEXPORT FPDF_BOOL STDCALL
FPDFAttachment_SetStringValue(FPDF_ATTACHMENT attachment,
                              FPDF_WIDESTRING key,
                              FPDF_WIDESTRING value) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  if (!pFile)
    return false;

  CPDF_Dictionary* pParamsDict = CPDF_FileSpec(pFile).GetParamsDict();
  if (!pParamsDict)
    return false;

  CFX_ByteString bsKey = CFXByteStringFromFPDFWideString(key);
  CFX_ByteString bsValue = CFXByteStringFromFPDFWideString(value);
  bool bEncodedAsHex = bsKey == "CheckSum";
  if (bEncodedAsHex)
    bsValue = CFXByteStringHexDecode(bsValue);

  pParamsDict->SetNewFor<CPDF_String>(bsKey, bsValue, bEncodedAsHex);
  return true;
}

DLLEXPORT unsigned long STDCALL
FPDFAttachment_GetStringValue(FPDF_ATTACHMENT attachment,
                              FPDF_WIDESTRING key,
                              void* buffer,
                              unsigned long buflen) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  if (!pFile)
    return 0;

  CPDF_Dictionary* pParamsDict = CPDF_FileSpec(pFile).GetParamsDict();
  if (!pParamsDict)
    return 0;

  CFX_ByteString bsKey = CFXByteStringFromFPDFWideString(key);
  CFX_WideString value = pParamsDict->GetUnicodeTextFor(bsKey);
  if (bsKey == "CheckSum" && !value.IsEmpty()) {
    CPDF_String* stringValue = pParamsDict->GetObjectFor(bsKey)->AsString();
    if (stringValue->IsHex()) {
      value =
          CPDF_String(nullptr, PDF_EncodeString(stringValue->GetString(), true),
                      false)
              .GetUnicodeText();
    }
  }

  return Utf16EncodeMaybeCopyAndReturnLength(value, buffer, buflen);
}

DLLEXPORT FPDF_BOOL STDCALL FPDFAttachment_SetFile(FPDF_ATTACHMENT attachment,
                                                   FPDF_DOCUMENT document,
                                                   const void* contents,
                                                   const unsigned long len) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
  if (!pFile || !pFile->IsDictionary() || !pDoc || len > INT_MAX)
    return false;

  // An empty content must have a zero length.
  if (!contents && len != 0)
    return false;

  // Create a dictionary for the new embedded file stream.
  auto pFileStreamDict = pdfium::MakeUnique<CPDF_Dictionary>();
  CPDF_Dictionary* pParamsDict =
      pFileStreamDict->SetNewFor<CPDF_Dictionary>("Params");

  // Set the size of the new file in the dictionary.
  pFileStreamDict->SetNewFor<CPDF_Number>("DL", static_cast<int>(len));
  pParamsDict->SetNewFor<CPDF_Number>("Size", static_cast<int>(len));

  // Set the creation date of the new attachment in the dictionary.
  CFX_DateTime dateTime;
  dateTime.Now();
  CFX_ByteString bsDateTime;
  bsDateTime.Format("D:%d%02d%02d%02d%02d%02d", dateTime.GetYear(),
                    dateTime.GetMonth(), dateTime.GetDay(), dateTime.GetHour(),
                    dateTime.GetMinute(), dateTime.GetSecond());
  pParamsDict->SetNewFor<CPDF_String>("CreationDate", bsDateTime, false);

  // Set the checksum of the new attachment in the dictionary.
  pParamsDict->SetNewFor<CPDF_String>(
      "CheckSum", CFXByteStringHexDecode(GenerateMD5Base16(contents, len)),
      true);

  // Create the file stream and have the filespec dictionary link to it.
  std::unique_ptr<uint8_t, FxFreeDeleter> stream(FX_Alloc(uint8_t, len));
  memcpy(stream.get(), contents, len);
  CPDF_Stream* pFileStream = pDoc->NewIndirect<CPDF_Stream>(
      std::move(stream), len, std::move(pFileStreamDict));
  CPDF_Dictionary* pEFDict =
      pFile->AsDictionary()->SetNewFor<CPDF_Dictionary>("EF");
  pEFDict->SetNewFor<CPDF_Reference>("F", pDoc, pFileStream->GetObjNum());
  return true;
}

DLLEXPORT unsigned long STDCALL
FPDFAttachment_GetFile(FPDF_ATTACHMENT attachment,
                       void* buffer,
                       unsigned long buflen) {
  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
  if (!pFile)
    return 0;

  CPDF_Stream* pFileStream = CPDF_FileSpec(pFile).GetFileStream();
  if (!pFileStream)
    return 0;

  uint8_t* data = pFileStream->GetRawData();
  uint32_t len = pFileStream->GetRawSize();
  CPDF_Dictionary* pFileDict = pFileStream->GetDict();
  if (!pFileDict || pFileDict->GetStringFor("Filter").IsEmpty()) {
    if (buffer && buflen >= len)
      memcpy(buffer, data, len);

    return len;
  }

  // Decode the stream if a stream filter is specified.
  uint8_t* decodedData = nullptr;
  uint32_t decodedLen = 0;
  CPDF_StreamParser::DecodeInlineStream(
      data, len, pFileDict->GetIntegerFor("Width"),
      pFileDict->GetIntegerFor("Height"), pFileDict->GetStringFor("Filter"),
      pFileDict->GetDictFor("DecodeParms"), &decodedData, &decodedLen);
  if (buffer && buflen >= decodedLen)
    memcpy(buffer, decodedData, decodedLen);

  FX_Free(decodedData);
  return decodedLen;
}