curlmultiparthandler.h

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#ifndef ZYPPNG_CURLMULTIPARTHANDLER_H
#define ZYPPNG_CURLMULTIPARTHANDLER_H
 
#include <zypp-core/zyppng/base/Base>
#include <zypp-core/zyppng/core/ByteArray>
#include <zypp-core/Digest.h>
#include <zypp-core/zyppng/pipelines/Expected>
#include <zypp-curl/ng/network/NetworkRequestError>
 
#include <optional>
#include <any>
 
namespace zyppng {
 
  class CurlMultiPartDataReceiver {
  public:
    virtual ~CurlMultiPartDataReceiver() = default;
 
    virtual size_t headerfunction ( char *ptr, size_t bytes ) = 0;
 
    virtual size_t writefunction  ( char *ptr, std::optional<off_t> offset, size_t bytes ) = 0;
 
    virtual bool beginRange       ( off_t range, std::string &cancelReason ) { return true; };
 
    virtual bool finishedRange    ( off_t range, bool validated, std::string &cancelReason ) { return true; };
  };
 
  class CurlMultiPartHandler : public Base
  {
    public:
 
      enum class ProtocolMode{
        Basic, //< use this mode if no special checks are required in header or write callbacks
        HTTP     //< this mode is used for HTTP and HTTPS downloads
      };
 
      // when requesting ranges from the server, we need to make sure not to request
      // too many at the same time. Instead we batch our requests and reuse the open
      // connection until we have the full file.
      // However different server have different maximum nr of ranges, so we start with
      // a high number and decrease until we find a rangecount that works
      constexpr static unsigned _rangeAttempt[] = {
        255,
        127,
        63,
        15,
        5,
        1
      };
 
      constexpr static unsigned _rangeAttemptSize = ( sizeof( _rangeAttempt ) / sizeof(unsigned) );
 
      enum State {
        Pending,    //< waiting to be dispatched
        Running,    //< currently running
        Finished,   //< finished successfully
        Error,      //< Error, use error function to figure out the issue
      };
 
      using CheckSumBytes = UByteArray;
      using Code = NetworkRequestError::Type;
 
      struct Range {
        size_t start = 0;
        size_t len = 0;
        size_t bytesWritten = 0;
        std::optional<zypp::Digest> _digest = {}; //< zypp::Digest that is updated when data is written, can be used to validate the file contents with a checksum
 
        CheckSumBytes _checksum;
        std::optional<size_t> _relevantDigestLen; //< If this is initialized , it defines how many bytes of the resulting checkum are compared
        std::optional<size_t> _chksumPad;   //< If initialized we need to pad the digest with zeros before calculating the final checksum
        std::any userData; //< Custom data the user can associate with the Range
 
        State _rangeState = State::Pending; //< Flag to know if this range has been already requested and if the request was successful
 
        void restart();
        Range clone() const;
 
        static Range make ( size_t start, size_t len = 0, std::optional<zypp::Digest> &&digest = {}, CheckSumBytes &&expectedChkSum = CheckSumBytes(), std::any &&userData = std::any(), std::optional<size_t> digestCompareLen = {}, std::optional<size_t> _dataBlockPadding = {} );
      };
 
      CurlMultiPartHandler( ProtocolMode mode, void *easyHandle, std::vector<Range> &ranges, CurlMultiPartDataReceiver &receiver );
      ~CurlMultiPartHandler();
 
      void *easyHandle() const;
      bool canRecover() const;
      bool hasMoreWork() const;
 
      bool hasError() const;
 
      Code lastError() const;
      const std::string &lastErrorMessage() const;
 
      bool validateRange(Range &rng);
 
      bool prepare( );
      bool prepareToContinue( );
      void finalize( );
 
      bool verifyData( );
 
      std::optional<size_t> reportedFileSize() const;
      std::optional<off_t>  currentRange() const;
 
  private:
 
      void setCode ( Code c, std::string msg, bool force = false );
 
      static size_t curl_hdrcallback ( char *ptr, size_t size, size_t nmemb, void *userdata );
      static size_t curl_wrtcallback ( char *ptr, size_t size, size_t nmemb, void *userdata );
 
      size_t hdrcallback ( char *ptr, size_t size, size_t nmemb );
      size_t wrtcallback ( char *ptr, size_t size, size_t nmemb );
      bool parseContentRangeHeader(const std::string_view &line, size_t &start, size_t &len, size_t &fileLen);
      bool parseContentTypeMultiRangeHeader(const std::string_view &line, std::string &boundary);
      bool checkIfRangeChkSumIsValid( Range &rng );
      void setRangeState ( Range &rng, State state );
 
      ProtocolMode _protocolMode = ProtocolMode::HTTP;
      void *_easyHandle = nullptr;
      CurlMultiPartDataReceiver &_receiver;
 
      Code _lastCode       = Code::NoError;
      std::string _lastErrorMsg;
 
      bool _allHeadersReceived = false; //< set to true once writefunc was called once e.g. all headers have been received
      bool _gotContentRangeInfo = false; //< Set to true if the server indicates ranges
      bool _isMuliPartResponse  = false; //< Set to true if the respone is in multipart form
 
      std::string _seperatorString; 
      std::vector<char> _rangePrefaceBuffer; 
 
      std::optional<off_t> _currentRange;
      std::optional<Range> _currentSrvRange;
      std::optional<size_t> _reportedFileSize; 
 
      unsigned _rangeAttemptIdx = 0;
      std::vector<Range>  &_requestedRanges; 
  };
 
} // namespace zyppng
 
#endif // ZYPPNG_CURLMULTIPARTHANDLER_H