有没有巨牛，这个东西有些冷门，资料不多

bsnry 2012-06-08 02:54:49

描述：需要做一个snmp agent，于是在codproject 找到了范例，按照作者的意思，搞成个dll，然后注册到代理计算机上

，然后网络管理员在服务端使用snmptil.exe即可查询到一些信息。

问题：由于我要做一个agent，然后给注册到机子上，给网络管理员使用，让管理员查询一些信息。

这是代码，dll的。

我不明白，代理机子是怎么发送信息给网管的，仅仅是一个dll而已。

还有，我如何修改呢，比如：我需要获取cpu的温度什么的？？

第三个问题：代码中的三个函数 SnmpExtensionInit SnmpExtensionQuery SnmpExtensionTrap 居然已经在库snmpapi.lib中有。但是作者还是自己实现了。

我如果在作者的基础上修改代码，应该如何修改呢？？？

http://www.codeproject.com/Articles/9024/How-to-develop-a-SNMP-extension-agent-DLL

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bsnry 2012-06-08

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// MyAgent.cpp : Defines the entry point for the DLL application.

//



#include "stdafx.h"

#include <snmp.h>

#include <malloc.h>



#define OID_SIZEOF( Oid )      ( sizeof Oid / sizeof(UINT) )



// template MIB entry

struct MIB_ENTRY

{

	AsnObjectIdentifier asnOid;

	void *              pStorageValue;

	CHAR *              szStorageName;

	BYTE                chType;

	UINT                unAccess;

	MIB_ENTRY*			pMibNext;

};



// this is the our branch starting point (clled prefix)

UINT g_unMyOIDPrefix[]	= {1, 3, 6, 1, 4, 1, 15};



// this is the trap OID to send to client

UINT g_TrapOid[]		= {1, 3, 6, 1, 4, 1, 15, 0};



AsnObjectIdentifier MIB_OidPrefix = { OID_SIZEOF(g_unMyOIDPrefix), g_unMyOIDPrefix};



DWORD g_dwStartTime = 0;

HANDLE g_hSimulateTrap = NULL;

HANDLE g_hTrapGenThread = NULL;

unsigned long __stdcall TrapGenThread(void *lpVoid);



int GetRequest(SnmpVarBind *pVarBind);

int GetNextRequest(SnmpVarBind *pVarBind);

int SetRequest(SnmpVarBind *pVarBind);



UINT GetStoreVar(MIB_ENTRY* pMIB, AsnAny *pasnValue);

UINT SetStoreVar(MIB_ENTRY* pMIB, AsnAny asnValue);





/////////MIB Table ////////////////////////////////////////////////

UINT g_unAboutOid[] = {0,0,1};

UINT g_unNameOid[] = {0,0,2};

UINT g_unAgeOid[] = {0,0,3};



char *g_szAbout = NULL;

char *g_szName = NULL;

AsnInteger g_asnIntAge = 0;



/// This is the MIB table and its related variable store

//    here evry thing is hard-coded to demonstration perpose

//    Actualy it should be loaded from the registry or from some file

MIB_ENTRY g_MyMibTable[] = {

	{	

		{OID_SIZEOF(g_unAboutOid),g_unAboutOid},

		&g_szAbout,

		"About",

		ASN_OCTETSTRING,

		SNMP_ACCESS_READ_ONLY,

		&g_MyMibTable[1]

	},

	{

		{OID_SIZEOF(g_unNameOid),g_unNameOid},

		&g_szName,

		"Name",

		ASN_OCTETSTRING,

		SNMP_ACCESS_READ_WRITE,

		&g_MyMibTable[2]

	},

	{

		{OID_SIZEOF(g_unAgeOid),g_unAgeOid},

		&g_asnIntAge,

		"Age",

		ASN_INTEGER,

		SNMP_ACCESS_READ_WRITE,

		NULL

	}

};



UINT g_unMyMibCount = (sizeof(g_MyMibTable) / sizeof(MIB_ENTRY));

///////////////////////////////////////////////////////////////////



BOOL APIENTRY DllMain( HANDLE hModule,DWORD  ul_reason_for_call, LPVOID lpReserved)

{

	switch (ul_reason_for_call)

	{

		case DLL_PROCESS_ATTACH:

			break;

		case DLL_THREAD_ATTACH:

			break;

		case DLL_THREAD_DETACH:

			break;

		case DLL_PROCESS_DETACH:

			TerminateThread(g_hTrapGenThread,0);

			CloseHandle(g_hTrapGenThread);

			CloseHandle(g_hSimulateTrap);

			break;

    }

    return TRUE;

}



// When exported funtion will be called during DLL loading and initialization

BOOL SNMP_FUNC_TYPE SnmpExtensionInit(DWORD dwUptimeReference,HANDLE *phSubagentTrapEvent, AsnObjectIdentifier *pFirstSupportedRegion)

{

	g_hSimulateTrap = CreateEvent(NULL, FALSE, FALSE, NULL); // creaet this event for the trap



	*pFirstSupportedRegion = MIB_OidPrefix;

	*phSubagentTrapEvent = g_hSimulateTrap; // by assigning it pass it to the SNMP service

											// So when ever you set this event service will call 

											// SnmpExtensionTrap exported function

	

	// on loading the our SNMP DLL create the thread

	g_hTrapGenThread = CreateThread(NULL,0,TrapGenThread,NULL,0,NULL);



	// hard coded initialization

	g_szAbout = (char*)malloc(sizeof(char)*64);

	strcpy(g_szAbout,"Author : Ramanan.T");

	g_szName = (char*)malloc(sizeof(char)*64);

	strcpy(g_szName,"Your Name");

	g_asnIntAge = 0;



	g_dwStartTime = GetTickCount();



	return SNMPAPI_NOERROR;

}



// this export is to query the MIB table and fields

BOOL SNMP_FUNC_TYPE SnmpExtensionQuery(BYTE bPduType, SnmpVarBindList *pVarBindList, AsnInteger32 *pErrorStatus, AsnInteger32 *pErrorIndex)

{

	int nRet = 0;

	AsnObjectName;

	

	*pErrorStatus = SNMP_ERRORSTATUS_NOERROR;

	*pErrorIndex = 0;



	for(UINT i=0;i<pVarBindList->len;i++)

	{

		*pErrorStatus = SNMP_ERRORSTATUS_NOERROR;



		// what type of request we are getting?

		switch(bPduType)

		{

		case SNMP_PDU_GET:// // gets the variable value passed variable in pVarBindList

			*pErrorStatus = GetRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		case SNMP_PDU_GETNEXT: // gets the next variable related to the passed variable in pVarBindList

			*pErrorStatus = GetNextRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		case SNMP_PDU_SET: // sets a variable

			*pErrorStatus = SetRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		default:

			*pErrorStatus = SNMP_ERRORSTATUS_NOSUCHNAME;

			*pErrorIndex++;

		};

	}	



	return SNMPAPI_NOERROR;

}



// this function just simulate traps

//   Traps just a 2 variables value from MIB

//  Trap is kind of event from server to client

///         When ever the event is set service will call this function and gets the parameters filled.

//       After filling the parameters service willsend the trap to all the client connected

BOOL SNMP_FUNC_TYPE SnmpExtensionTrap(AsnObjectIdentifier *pEnterpriseOid, AsnInteger32 *pGenericTrapId, AsnInteger32 *pSpecificTrapId, AsnTimeticks *pTimeStamp, SnmpVarBindList *pVarBindList)

{

	static int nNoOfTraps = 1; // just ignore this, I introduced this to send meny traps at once

								// any way below we are generating one trap with two values



	if(nNoOfTraps) // if it is zero don't send traps

	{

		pEnterpriseOid->idLength = sizeof(g_TrapOid);

		pEnterpriseOid->ids = g_TrapOid;



		*pGenericTrapId		= SNMP_GENERICTRAP_ENTERSPECIFIC;

		*pSpecificTrapId	= 1;   // ToasterControl Up trap.

		*pTimeStamp			= GetTickCount() - g_dwStartTime;



		// Allocate space for the Variable Bindings.

		pVarBindList->list = (SnmpVarBind*)SnmpUtilMemAlloc(2*sizeof(SnmpVarBind));



		SnmpUtilOidCpy(&pVarBindList->list[0].name,&MIB_OidPrefix);

		SnmpUtilOidAppend(&pVarBindList->list[0].name,&g_MyMibTable[1].asnOid);

		pVarBindList->list[0].value.asnType = ASN_OCTETSTRING;

		pVarBindList->list[0].value.asnValue.string.dynamic = TRUE;

		pVarBindList->list[0].value.asnValue.string.length = strlen(*(LPSTR*)g_MyMibTable[1].pStorageValue);

		pVarBindList->list[0].value.asnValue.string.stream =(unsigned char*)SnmpUtilMemAlloc(pVarBindList->list[0].value.asnValue.string.length * sizeof(char));

		memcpy(pVarBindList->list[0].value.asnValue.string.stream,*(LPSTR*)g_MyMibTable[1].pStorageValue,pVarBindList->list[0].value.asnValue.string.length);

				

		SnmpUtilOidCpy(&pVarBindList->list[1].name,&MIB_OidPrefix);

		SnmpUtilOidAppend(&pVarBindList->list[1].name,&g_MyMibTable[2].asnOid);

		pVarBindList->list[1].value.asnType = ASN_INTEGER;

		pVarBindList->list[1].value.asnValue.number = *((AsnInteger32*)g_MyMibTable[2].pStorageValue);



		pVarBindList->len = 2;



		nNoOfTraps--;

		// Indicate that valid trap data exists in the parameters.

		return TRUE;

	}

	nNoOfTraps = 1;

	// Indicate that no more traps are available, and parameters do not refer to any valid data

	return FALSE;

}

bsnry 2012-06-08

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// When exported funtion will be called during DLL loading and initialization

BOOL SNMP_FUNC_TYPE SnmpExtensionInit(DWORD dwUptimeReference,HANDLE *phSubagentTrapEvent, AsnObjectIdentifier *pFirstSupportedRegion)

{

	g_hSimulateTrap = CreateEvent(NULL, FALSE, FALSE, NULL); // creaet this event for the trap



	*pFirstSupportedRegion = MIB_OidPrefix;

	*phSubagentTrapEvent = g_hSimulateTrap; // by assigning it pass it to the SNMP service

											// So when ever you set this event service will call 

											// SnmpExtensionTrap exported function

	

	// on loading the our SNMP DLL create the thread

	g_hTrapGenThread = CreateThread(NULL,0,TrapGenThread,NULL,0,NULL);



	// hard coded initialization

	g_szAbout = (char*)malloc(sizeof(char)*64);

	strcpy(g_szAbout,"Author : Ramanan.T");

	g_szName = (char*)malloc(sizeof(char)*64);

	strcpy(g_szName,"Your Name");

	g_asnIntAge = 0;



	g_dwStartTime = GetTickCount();



	return SNMPAPI_NOERROR;

}



// this export is to query the MIB table and fields

BOOL SNMP_FUNC_TYPE SnmpExtensionQuery(BYTE bPduType, SnmpVarBindList *pVarBindList, AsnInteger32 *pErrorStatus, AsnInteger32 *pErrorIndex)

{

	int nRet = 0;

	AsnObjectName;

	

	*pErrorStatus = SNMP_ERRORSTATUS_NOERROR;

	*pErrorIndex = 0;



	for(UINT i=0;i<pVarBindList->len;i++)

	{

		*pErrorStatus = SNMP_ERRORSTATUS_NOERROR;



		// what type of request we are getting?

		switch(bPduType)

		{

		case SNMP_PDU_GET:// // gets the variable value passed variable in pVarBindList

			*pErrorStatus = GetRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		case SNMP_PDU_GETNEXT: // gets the next variable related to the passed variable in pVarBindList

			*pErrorStatus = GetNextRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		case SNMP_PDU_SET: // sets a variable

			*pErrorStatus = SetRequest(&pVarBindList->list[i]);

			if(*pErrorStatus != SNMP_ERRORSTATUS_NOERROR)

				*pErrorIndex++;

			break;

		default:

			*pErrorStatus = SNMP_ERRORSTATUS_NOSUCHNAME;

			*pErrorIndex++;

		};

	}	



	return SNMPAPI_NOERROR;

}



// this function just simulate traps

//   Traps just a 2 variables value from MIB

//  Trap is kind of event from server to client

///         When ever the event is set service will call this function and gets the parameters filled.

//       After filling the parameters service willsend the trap to all the client connected

BOOL SNMP_FUNC_TYPE SnmpExtensionTrap(AsnObjectIdentifier *pEnterpriseOid, AsnInteger32 *pGenericTrapId, AsnInteger32 *pSpecificTrapId, AsnTimeticks *pTimeStamp, SnmpVarBindList *pVarBindList)

{

	static int nNoOfTraps = 1; // just ignore this, I introduced this to send meny traps at once

								// any way below we are generating one trap with two values



	if(nNoOfTraps) // if it is zero don't send traps

	{

		pEnterpriseOid->idLength = sizeof(g_TrapOid);

		pEnterpriseOid->ids = g_TrapOid;



		*pGenericTrapId		= SNMP_GENERICTRAP_ENTERSPECIFIC;

		*pSpecificTrapId	= 1;   // ToasterControl Up trap.

		*pTimeStamp			= GetTickCount() - g_dwStartTime;



		// Allocate space for the Variable Bindings.

		pVarBindList->list = (SnmpVarBind*)SnmpUtilMemAlloc(2*sizeof(SnmpVarBind));



		SnmpUtilOidCpy(&pVarBindList->list[0].name,&MIB_OidPrefix);

		SnmpUtilOidAppend(&pVarBindList->list[0].name,&g_MyMibTable[1].asnOid);

		pVarBindList->list[0].value.asnType = ASN_OCTETSTRING;

		pVarBindList->list[0].value.asnValue.string.dynamic = TRUE;

		pVarBindList->list[0].value.asnValue.string.length = strlen(*(LPSTR*)g_MyMibTable[1].pStorageValue);

		pVarBindList->list[0].value.asnValue.string.stream =(unsigned char*)SnmpUtilMemAlloc(pVarBindList->list[0].value.asnValue.string.length * sizeof(char));

		memcpy(pVarBindList->list[0].value.asnValue.string.stream,*(LPSTR*)g_MyMibTable[1].pStorageValue,pVarBindList->list[0].value.asnValue.string.length);

				

		SnmpUtilOidCpy(&pVarBindList->list[1].name,&MIB_OidPrefix);

		SnmpUtilOidAppend(&pVarBindList->list[1].name,&g_MyMibTable[2].asnOid);

		pVarBindList->list[1].value.asnType = ASN_INTEGER;

		pVarBindList->list[1].value.asnValue.number = *((AsnInteger32*)g_MyMibTable[2].pStorageValue);



		pVarBindList->len = 2;



		nNoOfTraps--;

		// Indicate that valid trap data exists in the parameters.

		return TRUE;

	}

	nNoOfTraps = 1;

	// Indicate that no more traps are available, and parameters do not refer to any valid data

	return FALSE;

}

bsnry 2012-06-08

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// MyAgent.cpp : Defines the entry point for the DLL application.

//



#include "stdafx.h"

#include <snmp.h>

#include <malloc.h>



#define OID_SIZEOF( Oid )      ( sizeof Oid / sizeof(UINT) )



// template MIB entry

struct MIB_ENTRY

{

	AsnObjectIdentifier asnOid;

	void *              pStorageValue;

	CHAR *              szStorageName;

	BYTE                chType;

	UINT                unAccess;

	MIB_ENTRY*			pMibNext;

};



// this is the our branch starting point (clled prefix)

UINT g_unMyOIDPrefix[]	= {1, 3, 6, 1, 4, 1, 15};



// this is the trap OID to send to client

UINT g_TrapOid[]		= {1, 3, 6, 1, 4, 1, 15, 0};



AsnObjectIdentifier MIB_OidPrefix = { OID_SIZEOF(g_unMyOIDPrefix), g_unMyOIDPrefix};



DWORD g_dwStartTime = 0;

HANDLE g_hSimulateTrap = NULL;

HANDLE g_hTrapGenThread = NULL;

unsigned long __stdcall TrapGenThread(void *lpVoid);



int GetRequest(SnmpVarBind *pVarBind);

int GetNextRequest(SnmpVarBind *pVarBind);

int SetRequest(SnmpVarBind *pVarBind);



UINT GetStoreVar(MIB_ENTRY* pMIB, AsnAny *pasnValue);

UINT SetStoreVar(MIB_ENTRY* pMIB, AsnAny asnValue);





/////////MIB Table ////////////////////////////////////////////////

UINT g_unAboutOid[] = {0,0,1};

UINT g_unNameOid[] = {0,0,2};

UINT g_unAgeOid[] = {0,0,3};



char *g_szAbout = NULL;

char *g_szName = NULL;

AsnInteger g_asnIntAge = 0;



/// This is the MIB table and its related variable store

//    here evry thing is hard-coded to demonstration perpose

//    Actualy it should be loaded from the registry or from some file

MIB_ENTRY g_MyMibTable[] = {

	{	

		{OID_SIZEOF(g_unAboutOid),g_unAboutOid},

		&g_szAbout,

		"About",

		ASN_OCTETSTRING,

		SNMP_ACCESS_READ_ONLY,

		&g_MyMibTable[1]

	},

	{

		{OID_SIZEOF(g_unNameOid),g_unNameOid},

		&g_szName,

		"Name",

		ASN_OCTETSTRING,

		SNMP_ACCESS_READ_WRITE,

		&g_MyMibTable[2]

	},

	{

		{OID_SIZEOF(g_unAgeOid),g_unAgeOid},

		&g_asnIntAge,

		"Age",

		ASN_INTEGER,

		SNMP_ACCESS_READ_WRITE,

		NULL

	}

};



UINT g_unMyMibCount = (sizeof(g_MyMibTable) / sizeof(MIB_ENTRY));

///////////////////////////////////////////////////////////////////



BOOL APIENTRY DllMain( HANDLE hModule,DWORD  ul_reason_for_call, LPVOID lpReserved)

{

	switch (ul_reason_for_call)

	{

		case DLL_PROCESS_ATTACH:

			break;

		case DLL_THREAD_ATTACH:

			break;

		case DLL_THREAD_DETACH:

			break;

		case DLL_PROCESS_DETACH:

			TerminateThread(g_hTrapGenThread,0);

			CloseHandle(g_hTrapGenThread);

			CloseHandle(g_hSimulateTrap);

			break;

    }

    return TRUE;

}