filter.h

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/*
* Filter
* (C) 1999-2007 Jack Lloyd
* (C) 2013 Joel Low
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_FILTER_H_
#define BOTAN_FILTER_H_

#include <botan/secmem.h>
#include <vector>
#include <string>

namespace Botan {

/**
* This class represents general abstract filter objects.
*/
class BOTAN_PUBLIC_API(2,0) Filter
   {
   public:
      /**
      * @return descriptive name for this filter
      */
      virtual std::string name() const = 0;

      /**
      * Write a portion of a message to this filter.
      * @param input the input as a byte array
      * @param length the length of the byte array input
      */
      virtual void write(const uint8_t input[], size_t length) = 0;

      /**
      * Start a new message. Must be closed by end_msg() before another
      * message can be started.
      */
      virtual void start_msg() { /* default empty */ }

      /**
      * Notify that the current message is finished; flush buffers and
      * do end-of-message processing (if any).
      */
      virtual void end_msg() { /* default empty */ }

      /**
      * Check whether this filter is an attachable filter.
      * @return true if this filter is attachable, false otherwise
      */
      virtual bool attachable() { return true; }

      virtual ~Filter() = default;
   protected:
      /**
      * @param in some input for the filter
      * @param length the length of in
      */
      virtual void send(const uint8_t in[], size_t length);

      /**
      * @param in some input for the filter
      */
      void send(uint8_t in) { send(&in, 1); }

      /**
      * @param in some input for the filter
      */
      template<typename Alloc>
      void send(const std::vector<uint8_t, Alloc>& in)
         {
         send(in.data(), in.size());
         }

      /**
      * @param in some input for the filter
      * @param length the number of bytes of in to send
      */
      template<typename Alloc>
      void send(const std::vector<uint8_t, Alloc>& in, size_t length)
         {
         BOTAN_ASSERT_NOMSG(length <= in.size());
         send(in.data(), length);
         }

      Filter();

      Filter(const Filter&) = delete;

      Filter& operator=(const Filter&) = delete;

   private:
      /**
      * Start a new message in *this and all following filters. Only for
      * internal use, not intended for use in client applications.
      */
      void new_msg();

      /**
      * End a new message in *this and all following filters. Only for
      * internal use, not intended for use in client applications.
      */
      void finish_msg();

      friend class Pipe;
      friend class Fanout_Filter;

      size_t total_ports() const;
      size_t current_port() const { return m_port_num; }

      /**
      * Set the active port
      * @param new_port the new value
      */
      void set_port(size_t new_port);

      size_t owns() const { return m_filter_owns; }

      /**
      * Attach another filter to this one
      * @param f filter to attach
      */
      void attach(Filter* f);

      /**
      * @param filters the filters to set
      * @param count number of items in filters
      */
      void set_next(Filter* filters[], size_t count);
      Filter* get_next() const;

      secure_vector<uint8_t> m_write_queue;
      std::vector<Filter*> m_next; // not owned
      size_t m_port_num, m_filter_owns;

      // true if filter belongs to a pipe --> prohibit filter sharing!
      bool m_owned;
   };

/**
* This is the abstract Fanout_Filter base class.
**/
class BOTAN_PUBLIC_API(2,0) Fanout_Filter : public Filter
   {
   protected:
      /**
      * Increment the number of filters past us that we own
      */
      void incr_owns() { ++m_filter_owns; }

      void set_port(size_t n) { Filter::set_port(n); }

      void set_next(Filter* f[], size_t n) { Filter::set_next(f, n); }

      void attach(Filter* f) { Filter::attach(f); }

   private:
      friend class Threaded_Fork;
      using Filter::m_write_queue;
      using Filter::total_ports;
      using Filter::m_next;
   };

/**
* The type of checking to be performed by decoders:
* NONE - no checks, IGNORE_WS - perform checks, but ignore
* whitespaces, FULL_CHECK - perform checks, also complain
* about white spaces.
*/
enum Decoder_Checking { NONE, IGNORE_WS, FULL_CHECK };

}

#endif