problem with development

ophelie6989

Hi,
i try to develop a monitoring in order to retrieve informations about agents. I have installed netxms agent on a computer and i try to communicate with him with an other. the communication between the two works but i have a problem for sending and receiving informations. I have looked at the code already developed by netxms and i tried to send and receive the same type of informations that the agents understand. i have done two files: One with the code and the other with the include that i need.

Here my file in c++:
/*--Include--*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#include "./include/CSCPMessage.h"

int main () {

    /*--création de la socket grâce à la fonction socket()--*/
    //socketId est un entier qui correspond à un descripteur de socket
    int socketId = socket(AF_INET,SOCK_STREAM,0);

    /*--Définition de la structure utilisée avec TCP/IP afin de pouvoir contacter l'hôte--*/
    struct sockaddr_in serveur;//adresse hôte à contacter
    serveur.sin_family = AF_INET;//Protocole internet
    serveur.sin_port = htons(4700);// Port d'écoute
    serveur.sin_addr.s_addr=inet_addr("192.168.0.142"); // inet_adrr permet de spécifier une IP spécifique à utiliser


    /*--Etablissement de la connexion avec le serveur--*/
    int taille = sizeof(serveur);
    int connexion = connect(socketId, (struct sockaddr *) &serveur,taille);
    // Gestion de l'erreur de la connexion
    if (connexion ==-1)
    {
        printf("Un probleme est survenu lors de la connexion au serveur");
    }



    /*--Envoi du message // Sending--*/
    CSCPMessage msg;//classe
int dwRqId;
int i=1;
dwRqId = i++;
msg.SetCode(0x0067);//classe
msg.SetId(dwRqId);//classe
CSCP_MESSAGE pRawMsg;//structure
pRawMsg = msg.CreateMessage();//createMesage fonction de la classe

    int message;
    message=send(socketId,&pRawMsg,sizeof(msg),0);// Ecriture du message msg dans la socket ayant pour descripteur socketId
    //Gestion de l'erreur de l'envoi
    if (message == -1)
    {
        printf("Un probleme est survenu lors de l'envoi du message au serveur");
    }

    printf("Message envoye par le manager : %s \n",&pRawMsg);
    printf("Message envoye par le manager : %s \n",&msg);

/*--Reception du message // Reception--*/
    int retour;
    CSCP_MESSAGE msg2;
CSCPMessage msg3;

retour=recv(socketId,&msg2,sizeof(msg2),0);// Lecture du message renvoyé par le serveur dans la socketayant pour descripteur socketId

//Gestion de l'erreur de la reception
    if (retour == -1)
    {
        printf("Un probleme est survenu lors de la reception du message du serveur");
    }

    //Affichage
printf("Message envoye par l agent : %s \n",&msg2);
int r=msg2.wCode;
printf("affichage du code du message structure: %d \n",&r);
msg3.SetCode(msg2.wCode);
printf("Message envoye par l agent : %s \n",&msg3);
int t=msg3.GetCode() ;
printf("affichage du code du message classe : %d \n",&t);

/*--Fermeture de la socket--*/
close(socketId);

return 0;
}// fin du main

Here my file in .h

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#ifndef _CSCPMessage_h_
#define _CSCPMessage_h_

#define VID_RCC ((float)28) /* RCC == Request Completion Code */
#define CMD_REQUEST_COMPLETED 0x001D
#define CMD_KEEPALIVE 0x0003

/*--Structure CSCP_DF--*/
typedef struct
{
int dwVarId; // Variable identifier
char bType; // Data type
char bPadding; // Padding
int wInt16;
union
{
int dwInteger;
int qwInt64;
double dFloat;
struct
{
int dwLen;
int szValue[1];
} string;
} data;
} CSCP_DF;

/*--Structure CSCP_MESSAGE--*/
typedef struct
{
int wCode; // Message (command) code
int wFlags; // Message flags
int dwSize; // Message size (including header) in bytes
float dwId; // Unique message identifier
float dwNumVars; // Number of variables in message

} CSCP_MESSAGE;

/*--Classe CSCPMessage--*/
class CSCPMessage
{
private:
int m_wCode;
int m_wFlags;
float m_dwId;
float m_dwNumVar; // Number of variables
CSCP_DF **m_ppVarList; // List of variables
int m_nVersion; // Protocol version

public:

CSCP_MESSAGE CreateMessage(void){
CSCP_MESSAGE msg;
msg.wCode= m_wCode;
return msg;

};
int GetCode(void) { return m_wCode; }
void SetCode(int wCode) { m_wCode = wCode; }

// DWORD GetId(void) { return m_dwId; }
void SetId(float dwId) { m_dwId = dwId; }

float GetVariableLong(float dwVarId);

};

class MsgWaitQueue
{
private:

void *WaitForMessageInternal(int wIsBinary, int wCode, float dwId, float dwTimeOut);

public:
MsgWaitQueue();
~MsgWaitQueue();

CSCPMessage *WaitForMessage(int wCode, int dwId, int dwTimeOut)
{
return (CSCPMessage *)WaitForMessageInternal(0, wCode, dwId, dwTimeOut);
}

};

#endif /* _CSCPMessage_h_ */

When i compile, i have that message:

# ./client3.e
Message envoye par le manager : g
Message envoye par le manager : g
Message envoye par l agent : g
affichage du code du message structure: -809671536
Message envoye par l agent : g
affichage du code du message classe : -809671540

The sending didn t work. can you help me, i am on it for 5 days and i don t know how to do it.

Thank you very much

Victor Kirhenshtein

Hello!

I see the following errors:

when you sending message to the agent, you give the wrong message size - instead of

send(socketId,&pRawMsg,sizeof(msg),0)

you should use

send(socketId,&pRawMsg,ntohl(pRawMsg->dwSize),0);

You use very small receive buffer - sizeof(CSCP_MESSAGE) will be something like 24 to 32 bytes, but incoming message could be much larger. You should use at least 1024 bytes buffer for receiving messages with single parameter's value and much larger if you wish to get lists from agent. We typically use buffers of 256KB. Other option is to receive message header first, check message size, and allocate buffer for received message dynamically.
Protocol messages use binary representation of data, so debugging with printf("%s") will not help much. You should print individual fields.
For header - there are many errors on different levels. I suggest you to use same declarations as in nms_cscp.h, especially for CSCP_MESSAGE and CSCP_DF structures, because they represents actual data positions in transmission stream. Don't forget to use #pragma pack or you will get incorrect results on some platforms or compilers.

And why you not using already written communication code in libnetxms and libnxsrv? libnxsrv contains ready to use C++ API for communicating with agents, which handles all communication and protocol things and gives you high level API.

Best regards,
Victor

ophelie6989

Thank you, i am going to look at libnetxms. For the header, i had changed types of variables because i wanted to try so;ething easy in order to see if it works. I am going to try like you said.
Thank you very much.

ophelie6989

Hi,
I have another questions , in order to test just the sending, i have created a file named client3.cpp which enable to connect with the agent.I also added in the fonction that is in the file Agent and which enable to send a message to the agent;
/*--Sending--*/
CSCPMessage *pMsg;
CSCP_MESSAGE *pRawMsg;
BOOL bResult;

pRawMsg = pMsg->CreateMessage();
bResult = (SendEx(m_hSocket, (char *)pRawMsg, ntohl(pRawMsg->dwSize), 0) == (int)ntohl(pRawMsg->dwSize));
free(pRawMsg);
return bResult;

In order to test. I create also a header where i have included the class and structure that i needed.

#ifndef _CSCPMessage_h_
#define _CSCPMessage_h_

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "nms_common.h"
//#include "netxms-regex.h"
#define VID_RCC ((float)28) /* RCC == Request Completion Code */
#define CMD_REQUEST_COMPLETED 0x001D
#define CMD_KEEPALIVE 0x0003

typedef struct
{
DWORD dwBufSize;
DWORD dwBufPos;
char szBuffer[10000000];
} CSCP_BUFFER;

/*--Structure CSCP_DF--*/
typedef struct
{
DWORD dwVarId; // Variable identifier
BYTE bType; // Data type
BYTE bPadding; // Padding
WORD wInt16;
union
{
DWORD dwInteger;
//QWORD qwInt64;
double dFloat;
struct
{
DWORD dwLen;
WORD szValue[1];
} string;
} data;
} CSCP_DF;

/*--Structure CSCP_MESSAGE--*/
typedef struct
{
WORD wCode; // Message (command) code
WORD wFlags; // Message flags
DWORD dwSize; // Message size (including header) in bytes
DWORD dwId; // Unique message identifier
DWORD dwNumVars; // Number of variables in message
CSCP_DF df[1]; // Data fields
} CSCP_MESSAGE;

/*--Classe CSCPMessage--*/
class LIBNETXMS_EXPORTABLE CSCPMessage
{
private:
WORD m_wCode;
WORD m_wFlags;
DWORD m_dwId;
DWORD m_dwNumVar; // Number of variables
CSCP_DF **m_ppVarList; // List of variables
int m_nVersion; // Protocol version

void *Set(DWORD dwVarId, BYTE bType, const void *pValue, DWORD dwSize = 0);
void *Get(DWORD dwVarId, BYTE bType);
DWORD FindVariable(DWORD dwVarId);
public:
CSCPMessage(int nVersion = NXCP_VERSION);
CSCPMessage(CSCPMessage *pMsg);
CSCPMessage(CSCP_MESSAGE *pMsg, int nVersion = NXCP_VERSION);
CSCPMessage(const char *xml);
~CSCPMessage();

CSCP_MESSAGE *CreateMessage(void);
char *CreateXML(void);
void ProcessXMLToken(void *state, const char **attrs);
void ProcessXMLData(void *state);

WORD GetCode(void) { return m_wCode; }
void SetCode(WORD wCode) { m_wCode = wCode; }

DWORD GetId(void) { return m_dwId; }
void SetId(DWORD dwId) { m_dwId = dwId; }

BOOL IsVariableExist(DWORD dwVarId) { return (FindVariable(dwVarId) != INVALID_INDEX) ? TRUE : FALSE; }
BOOL IsEndOfSequence(void) { return (m_wFlags & MF_END_OF_SEQUENCE) ? TRUE : FALSE; }
BOOL IsReverseOrder(void) { return (m_wFlags & MF_REVERSE_ORDER) ? TRUE : FALSE; }

void SetVariable(DWORD dwVarId, WORD wValue) { Set(dwVarId, CSCP_DT_INT16, &wValue); }
void SetVariable(DWORD dwVarId, DWORD dwValue) { Set(dwVarId, CSCP_DT_INTEGER, &dwValue); }
void SetVariable(DWORD dwVarId, QWORD qwValue) { Set(dwVarId, CSCP_DT_INT64, &qwValue); }
void SetVariable(DWORD dwVarId, double dValue) { Set(dwVarId, CSCP_DT_FLOAT, &dValue); }
void SetVariable(DWORD dwVarId, const TCHAR *pszValue) { Set(dwVarId, CSCP_DT_STRING, pszValue); }
void SetVariable(DWORD dwVarId, BYTE *pValue, DWORD dwSize) { Set(dwVarId, CSCP_DT_BINARY, pValue, dwSize); }
void SetVariableToInt32Array(DWORD dwVarId, DWORD dwNumElements, DWORD *pdwData);
BOOL SetVariableFromFile(DWORD dwVarId, const TCHAR *pszFileName);

DWORD GetVariableLong(DWORD dwVarId);
QWORD GetVariableInt64(DWORD dwVarId);
WORD GetVariableShort(DWORD dwVarId);
LONG GetVariableShortAsInt32(DWORD dwVarId);
double GetVariableDouble(DWORD dwVarId);
TCHAR *GetVariableStr(DWORD dwVarId, TCHAR *szBuffer = NULL, DWORD dwBufSize = 0);
DWORD GetVariableBinary(DWORD dwVarId, BYTE *pBuffer, DWORD dwBufSize);
DWORD GetVariableInt32Array(DWORD dwVarId, DWORD dwNumElements, DWORD *pdwBuffer);

void DeleteAllVariables(void);

void DisableEncryption(void) { m_wFlags |= MF_DONT_ENCRYPT; }
void SetEndOfSequence(void) { m_wFlags |= MF_END_OF_SEQUENCE; }
void SetReverseOrderFlag(void) { m_wFlags |= MF_REVERSE_ORDER; }

};
//
// Message waiting queue class
//

class LIBNETXMS_EXPORTABLE MsgWaitQueue
{
private:
MUTEX m_mutexDataAccess;
CONDITION m_condStop;
CONDITION m_condNewMsg;
DWORD m_dwMsgHoldTime;
DWORD m_dwNumElements;
WAIT_QUEUE_ELEMENT *m_pElements;
THREAD m_hHkThread;

void Lock(void) { MutexLock(m_mutexDataAccess, INFINITE); }
void Unlock(void) { MutexUnlock(m_mutexDataAccess); }
void HousekeeperThread(void);
void *WaitForMessageInternal(WORD wIsBinary, WORD wCode, DWORD dwId, DWORD dwTimeOut);

static THREAD_RESULT THREAD_CALL MWQThreadStarter(void *);

public:
MsgWaitQueue();
~MsgWaitQueue();

void Put(CSCPMessage *pMsg);
void Put(CSCP_MESSAGE *pMsg);
CSCPMessage *WaitForMessage(WORD wCode, DWORD dwId, DWORD dwTimeOut)
{
return (CSCPMessage *)WaitForMessageInternal(0, wCode, dwId, dwTimeOut);
}
CSCP_MESSAGE *WaitForRawMessage(WORD wCode, DWORD dwId, DWORD dwTimeOut)
{
return (CSCP_MESSAGE *)WaitForMessageInternal(1, wCode, dwId, dwTimeOut);
}

void Clear(void);
void SetHoldTime(DWORD dwHoldTime) { m_dwMsgHoldTime = dwHoldTime; }
};

#endif /* _CSCPMessage_h_ */

I include in it the link to "nms_common.h" for the definition of the type DWORD, word ETC.

In my makefile, i have integrated the file message.c
When i compile, it didn t work.

g++ client3.cpp -c -I /usr/local/include -I ./include -o client3.o
In file included from client3.cpp:11:
include/CSCPMessage.h:59: error: syntax error before `{' token
include/CSCPMessage.h:71: error: syntax error before `public'
In file included from client3.cpp:11:
include/CSCPMessage.h:4:1: unterminated #ifndef
*** Error code 1

There is a problem with the class CSCPMessage. Do i have forget a header to include?
I also wanted to know what is LIBNETXMS_EXPORTABLE?
I searched in the header nms util but i dont understand the using of it.

Sorry to disturb you :-
Thank you

Victor Kirhenshtein

This define is required for porting code to Windows. On Windows, if you want to export function or class from DLL, you should add __declspec(dllexport) to it's declaration. So, on Windows we define LIBNETXMS_EXPORTABLE as __declspec(dllexport) when building DLL, and on other platforms it simply defines to nothing. So, if you are not writing your code for Windows or not writing a Windows DLL you can simply remove this or define to nothing.

Best regards,
Victor

ophelie6989

Thank you, i have changed my code in consequences. I have done a sending and a receiving from the agent. I have again a question. I would like to know how i can test and display the message that i received from the agent by the fonction RecvCSCPMessage?
Thank you very much

Victor Kirhenshtein

Hi!

You should create CSCPMessage object from CSCP_MESSAGE structure filled by RecvNXCPMessage function. After that, you can access to variables inside message via GetVariableXxx methods of class CSCPMessage. If you getting parameter's value from agent, you should be interested in variables VID_RCC - DWORD holding response code, and VID_VALUE - received value as string.

Best regards,
Victor

ophelie6989

Thank you, but i dont understand the difference between RecvCSCPMessage() and RecvNXCPMessage()? I have used the fonction

BOOL AgentConnection::SendMessage(CSCPMessage *pMsg)
{
CSCP_MESSAGE *pRawMsg;
BOOL bResult;

   pRawMsg = pMsg->CreateMessage();
   bResult = (SendEx(m_hSocket, (char *)pRawMsg, ntohl(pRawMsg->dwSize), 0) == (int)ntohl(pRawMsg->dwSize));
   free(pRawMsg);
   return bResult;
}

to send a message to the agent and RecvCSCPMessage to receive a message from an agent. I have just seen the fonction Send NXCPMessage.
Which fonction do i have to use to send and receive a message?

Thank you very much

Victor Kirhenshtein

CSCP is an old name for NXCP, and it's partially replaces in the code. In latest versions, there are no RecvCSCPMessage() function, only RecvNXCPMessage() - but it's the same function anyway.

Best regards,
Victor

ophelie6989

ok thank you. i have seen that RecvNXCPMessage take in parameters a CSCP_ENCRYPTION_CONTEXT. That means that the message that i receive from the agent is crypted and that i have to decrypted it?
Thank you

Victor Kirhenshtein

Yes, it could be encrypted, and in that case you should provide correct encryption context. However, if you are not using encryption, you can simple pass NULL.

Best regards,
Victor

ophelie6989

Thank you, i am going to use the fonction SendFileOverNXCP to send a message to the agent and RecvNXCPMessage to receive a message from the agent.

ophelie6989

In fact i am not sure that the fonction SendFileOverNXCP is used to send a message to the agent.

How can i do to send a message to the agent and to receive it? I have used RecvNXCPMessage but i dont arrive to see the message sent by the agent.
What are the steps for the sending and the reception of message?

Thank you very much

Victor Kirhenshtein

In general, steps are following:

create CSCPMessage object
fill it with necessary variables and set correct command code
create raw message (CSCP_MESSAGE) vith CSCPMessage::CreateMessage method
send raw message to agent as usual
receive response using RecvNXCPMessage function
create CSCPMessage object from received raw message
read variables from message object

Best regards,
Victor

ophelie6989

Thank you, it was what i had done. I have send to the Agent the code 0x0097 in order to get the server informations. But which variable did i have to read from the message object for having the information about the server?

Thank you very much

Victor Kirhenshtein

You don't need command 0x0097 to read information from agent. You should use CMD_GET_PARAMETER (0x0041) and set name of the parameter to variable VID_PARAMETER (85). Agent will reply with command CMD_REQUEST_COMPLETED (0x001D). First, check variable VID_RCC (28). If it contains 0, then value of requested parameter will be in variable VID_VALUE (21). For example:

CSCPMessage msg;

msg.SetCode(CMD_GET_PARAMETER);
msg.SetId(requestId);
msg.SetVariable(VID_PARAMETER, "Agent.Version");

DWORD rcc = response->GetVariableLong(VID_RCC);
if (rcc == ERR_SUCCESS)
{
char buffer[256];
response->GetVariableStr(VID_VALUE, buffer, 256);
// Now buffer contains value of requested parameter
}

Best regards,
Victor

ophelie6989

Thank you, i have tried what you told me. For the reception of a message from the agent i have done that:

CSCPMessage *pMsg2=new CSCPMessage(); //classe
CSCP_MESSAGE *pRawMsg2;//structure
CSCP_BUFFER *pMsgBuffer;//structure buffer

int iErr;
TCHAR szBuffer[128];

// Initialize raw message receiving function
pMsgBuffer = (CSCP_BUFFER *)malloc(sizeof(CSCP_BUFFER));
RecvNXCPMessage(socketId, pRawMsg2, pMsgBuffer, RECEIVER_BUFFER_SIZE,0,0,0);

// Allocate space for raw message
pRawMsg2 = (CSCP_MESSAGE *)malloc(RECEIVER_BUFFER_SIZE);
pMsg2 = new CSCPMessage(pRawMsg2);

DWORD rcc = pMsg2->GetVariableLong(VID_RCC);

if (rcc == ERR_SUCCESS)
{

char buffer[256];

pMsg2->GetVariableStr(VID_VALUE, buffer, 256);
// Now buffer contains value of requested parameter

int compteur;
for(compteur=0;compteur<256;compteur++)
{

                     printf("%c\n",buffer[compteur]);

                }//fin du for

}// fin if

But i always don t managed to read informations. I have done a prinft to see what informations are in the buffer but when i compiled nothing appeared in the buffer.
What do i have to do in order to see the informations that i received from the Agent

Victor Kirhenshtein

You have missed code for actual message reception. Instead of

// Initialize raw message receiving function
pMsgBuffer = (CSCP_BUFFER *)malloc(sizeof(CSCP_BUFFER));
RecvNXCPMessage(socketId, pRawMsg2, pMsgBuffer, RECEIVER_BUFFER_SIZE,0,0,0);

// Allocate space for raw message
pRawMsg2 = (CSCP_MESSAGE *)malloc(RECEIVER_BUFFER_SIZE);
pMsg2 = new CSCPMessage(pRawMsg2);

you should have something like

// Initialize raw message receiving function
pMsgBuffer = (CSCP_BUFFER *)malloc(sizeof(CSCP_BUFFER));
RecvNXCPMessage(0, NULL, pMsgBuffer, RECEIVER_BUFFER_SIZE,0,0,0);

CSCP_ENCRYPTION_CONTEXT *nullContext = NULL;
pRawMsg2 = (CSCP_MESSAGE *)malloc(RECEIVER_BUFFER_SIZE);
RecvNXCPMessage(socketId, pRawMsg2, pMsgBuffer, RECEIVER_BUFFER_SIZE,&nullContext,NULL,0);
pMsg2 = new CSCPMessage(pRawMsg2);

Best regards,
Victor

ophelie6989

Hi, thank you and Happy New Year!!
I have done what you said to me but the message send from the agent didn t work again.

I have that:
-----------Envoi du message a l agent-----------
code du message : A

-----------Reception du message de l agent-----------
¨

When i send CMD_GETPAREMETER, i receive ".." with the code that i show you previously.

How can i do to see the parameters?

Thank you again

Victor Kirhenshtein

Hello!

Did you set VID_PARAMETER variable before sending CMD_GET_PARAMETER request? You should have something like

msg.SetVariable(VID_PARAMETER, "Agent.Version");

before converting message into binary format and sending. Also, check VID_RCC variable in response message - may be it contains error.

Best regards,
Victor

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