filter.h

#ifndef N2NCFILTER_H
#define N2NCFILTER_H

// #define FILTER_CONST_CONTINUE 0
// #define FILTER_CONST_RETURN 2
// #define FILTER_CONST_DROP 1


#include "nixsys.h"
// #include "n2nc.h"
#include "blowfish.h"
#include "packetmanager.h"

namespace n2nc {

class Filter{
  protected:
// public:
    std::string m_name ;
    std::string m_description ;
    bool m_isenabled ;
    size_t  m_maxoverhead ;
    
    std::string m_filename ;
    void *this_handle;
    
    security::BlowFish::key_t *m_skey ;
    n2nc::PacketManager *m_pkm ;
    
    /* raw information */
    n2nc::net::Socket *m_com_sock ;
    
    Filter(std::string name,std::string description){
      std::cerr << "loaded filter module: " << name << std::endl ;
      this->m_name = name ;
      this->m_description = description ;
      this->m_com_sock = NULL ;
      this->m_maxoverhead = 0 ;
    }

public:
    /* since plugin is linked alone, i need to define(assing) the enums */
    enum status_t{
      FILTER_CONTINUE = 0,
      FILTER_RETURN,
      FILTER_DROP
    };

    virtual ~Filter(){
      std::cerr << "UN-loaded filter module: " << this->m_name <<  std::endl ;
    }
    virtual status_t egress(void *inbuf, void *outbuf,size_t inlen,size_t *outlen) = 0 ;
    
    virtual status_t ingress(void *inbuf, void *outbuf,size_t inlen,size_t *outlen) = 0 ;
    
//     virtual status_t egress(void **buf,size_t *len) = 0 ;
//     virtual status_t ingress(void **buf,size_t *len) = 0 ;
    virtual int setSessionKey(security::BlowFish::key_t *key){ this->m_skey = key ;}
    virtual int setPKM(n2nc::PacketManager *pkm){this->m_pkm = pkm ;}
    virtual size_t getMaxOverHead(){  return this->m_maxoverhead ;}
    std::string toString(){
      std::ostringstream os;
      std::string s;
      os << "Name: " << this->m_name << " Description: " << this->m_description << " Filename: " << this->m_filename ;   ;
      s =  "Name: " + this->m_name + " Description: " + this->m_description + " Filename: " + this->m_filename  ;
      /* FIXME string */
      return os.str();
    }
    static Filter *load_filter(const std::string filename){
      void *handle ;
      Filter *ist;
      typedef Filter* (*get_istance_t)(/*void *argc,int argc*/);
      get_istance_t tmp_get_istance;
//       handle = dlopen(filename.c_str(),/*RTLD_LOCAL|RTLD_NOW*/ RTLD_LAZY );
      handle = dlopen(filename.c_str(),RTLD_NOW );
      if (handle==NULL){ std::cerr << "dlopen fails!:" << dlerror() << std::endl; return NULL ;}
      tmp_get_istance = (get_istance_t)dlsym(handle,"get_istance");
      if (tmp_get_istance ==NULL ) {std::cerr << "dlsym fails!:" << dlerror() << std::endl ; return NULL ;}
      ist = tmp_get_istance() ;
      ist->this_handle = handle ;
      ist->m_filename = filename ;
      return ist ;
    }
    static int free_filter(Filter *filter){
      void *handle;
      typedef int (*free_istance_t)(Filter *filter);
      free_istance_t tmp_free_istance;
      tmp_free_istance = (free_istance_t)dlsym(filter->this_handle,"free_istance");
      if (tmp_free_istance ==NULL ) {std::cerr << "dlsym fails!:" << dlerror(); exit(1);}
      handle = filter->this_handle ;
      //destructor call
      tmp_free_istance(filter);
      //module unload
      dlclose(handle);
    }



};


}//ns


#endif

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