source: Evidence/Bridge.cc@ 226

/********************************************************************\

  Bridge between two networks

  Subscription to top-level server list DIS_DNS/SERVER_LIST not via
  AddService() ensures AddService() only called from infoHandler(),
  thus serialized by DIM and no Mutex is necessary.

  Remote procedure calls are bridged through their underlying services
  and commands.
  
  Oliver Grimm, June 2010

\********************************************************************/

#define SERVER_NAME "Bridge"
#include "Evidence.h"

#include <string>
#include <vector>

const int DEFAULT_PORT = 2505;

using namespace std;


// Class declaration
class Bridge: public DimClient, public EvidenceServer {

        struct Item {
          string Name;
          DimCommand *Command;
          DimStampedInfo *DataItem;
          DimService *Service;
          char *Data;
        };
        vector<struct Item> List;

        DimInfo *ServerList;
        
    void infoHandler();
    void commandHandler();
        void AddService(string, char *, int);
        void RemoveService(string);
   
  public:
    Bridge(char *, int);
    ~Bridge();
}; 

// Constructor
Bridge::Bridge(char *Name, int Port): EvidenceServer(SERVER_NAME) {

  // Set primary DIM network to subscribe from
  DimClient::setDnsNode(Name, Port);

  // Subsribe to top-level server list
  ServerList = new DimInfo((char *) "DIS_DNS/SERVER_LIST", NO_LINK, this);
}


// Destructor: Delete all subscriptions and services
Bridge::~Bridge() {

  while (List.size() != 0) RemoveService(List[0].Name);  
  delete ServerList;
}


// Service subscription and repeating
void Bridge::infoHandler() {

  DimInfo *I = getInfo();

  // Check if service available
  if (!ServiceOK(I)) return;

  // If service is DIS_DNS/SERVER_LIST, subscribe to all SERVICE_LIST services
  if (strcmp(I->getName(), "DIS_DNS/SERVER_LIST") == 0) {       
        char *Token = strtok(I->getString(), "+-!@");   
        while (Token != NULL) {
          if (*I->getString() == '-' || *I->getString() == '!') {
                RemoveService(string(Token)+"/SERVICE_LIST");
          }
          else AddService(string(Token)+"/SERVICE_LIST", (char *) "C", DimSERVICE);

          // Skip server IP address and process ID
          Token = strtok(NULL, "|");
          Token = strtok(NULL, "@");
        }       
        return;
  }

  // If service is SERVICE_LIST, scan and subscribe/unsubscribe to services
  if (strstr(I->getName(), "/SERVICE_LIST") != NULL) {
        char *Format, *Name = strtok(I->getString(), "+-!|");
        while (Name != NULL) {
      if ((Format = strtok(NULL, "\n")) != NULL) {
            // Check if service added or removed/unavailable
            if (*I->getString() == '-' || *I->getString() == '!') {
                  if (strstr(Format, "|RPC") != NULL) {
                        RemoveService(string(Name)+"/RpcIn");
                        RemoveService(string(Name)+"/RpcOut");
                  }
                  else RemoveService(Name);
                }
                else {
                  // Determine type of service
                  if (strstr(Format, "|CMD") != NULL) {
                        *(strstr(Format, "|CMD")) = '\0';
                        AddService(Name, Format, DimCOMMAND);
                  }
                  else if (strstr(Format, "|RPC") != NULL) {
                        *(strstr(Format, "|RPC")) = '\0';
                    if (strchr(Format, ',') != NULL) {
                          *strchr(Format, ',') = '\0';
                          AddService(string(Name)+"/RpcIn", Format, DimCOMMAND);
                          AddService(string(Name)+"/RpcOut", Format+strlen(Format)+1, DimSERVICE);
                        }
                        
                  }
                  else {
                        Format[strlen(Format)-1] = '\0';
                        AddService(Name, Format, DimSERVICE);
                  }
                }
          }
          Name = strtok(NULL, "|");
        }
        return;
  }

  // Identify service and repeat to secondary DNS
  for (int Service=0; Service<List.size(); Service++) if (I == List[Service].DataItem) {

    // Copy service data
    delete[] List[Service].Data;
    List[Service].Data = new char [I->getSize()];
    memcpy(List[Service].Data, I->getData(), I->getSize());

        // Set new service properties and update service
    List[Service].Service->setQuality(I->getQuality());
    List[Service].Service->setTimestamp(I->getTimestamp(), I->getTimestampMillisecs()); 
        List[Service].Service->updateService(List[Service].Data, I->getSize());
  }
}


// Command repeating
void Bridge::commandHandler() {
 
  sendCommandNB(getCommand()->getName(), getCommand()->getData(), getCommand()->getSize());
}


// Service subscription
void Bridge::AddService(string Name, char *Format, int Type) {

  // Do not forward  DIS_DNS and History services
  if ((Name.find("DIS_DNS/") != string::npos) || (Name.find("History/") != string::npos)) return;

  // Check if already subscribed to this service
  for (int i=0; i<List.size(); i++) {
        if (Name == List[i].Name) return;
  }

  // Create subscription and service to secondary DNS or new command
  struct Item New = {Name, NULL, NULL, NULL, NULL};

  if  (Type == DimSERVICE) {  
        New.Service = new DimService(Name.c_str(), (char *) Format, New.Data, 0);
        New.DataItem = new DimStampedInfo(Name.c_str(), NO_LINK, this);
  }
  else if (Type == DimCOMMAND) New.Command = new DimCommand(Name.c_str(), Format, this);

  List.push_back(New);
}


// Remove service from watch list (unused pointer are NULL)
void Bridge::RemoveService(string Name) {

  vector<struct Item>::iterator E;
  for (E=List.begin(); E<List.end(); ++E) if (Name == (*E).Name) {
        delete (*E).DataItem;
        delete (*E).Service;
        delete[] (*E).Data;
        delete (*E).Command;

        List.erase(E);
  }
}


// Main program
int main(int argc, char *argv[]) {

  // Check command line argument
  if (argc == 1) {
        printf("Usage: %s <address of primary DNS> [port] (default port %d)\n", argv[0], DEFAULT_PORT);
        exit(EXIT_FAILURE);
  }
          
  // Static ensures calling of destructor by exit()
  static Bridge Class(argv[1], argc>2 ? atoi(argv[2]) : DEFAULT_PORT);
  
  // Sleep until signal caught
  pause();
}