snmp_encode.c

在freescale 的ne64上开发的源代码

#include "snmptype.h"
#if SNMP_WANTED==1
#include "snmpdef.h"
#include "snmpfunc.h"

/****************************************************************************
NAME:  Get_Vb_Size
PURPOSE:  Compute and set the internal length of a var bind
PARAMETERS:VB_T *  The VarBind to be sized.
RETURNS:  _UINT16     The number of octets the Var Bind would
                        use if ASN.1 encoded, including the var bind sequence
****************************************************************************/
_UINT16 Get_Vb_Size(VB_T * vbp)
{
	_UINT16 vb_size;			/* Accumulator of size of VarBind sequence */
	_UINT16 obj_size;

	obj_size = A_SizeOfObjectId((OBJ_ID_T *)&(vbp->vb_obj_id));
	vb_size = 1 /* The object ID tag is always 1 octet long */
	          + A_SizeOfLength(obj_size) + obj_size;

	switch (vbp->vb_data_flags_n_type)
	{
	case VT_NUMBER:
		vbp->vb_data_length = A_SizeOfInt(vbp->value_u.v_number);
		break;
	case VT_COUNTER:
	case VT_GAUGE:
	case VT_TIMETICKS:
		vbp->vb_data_length = A_SizeOfUnsignedInt(vbp->value_u.v_counter);
		break;
	case VT_STRING:
	case VT_OPAQUE:
		/*vbp->vb_data_length = strlen(vbp->value_u.v_string);*/
		break;
	case VT_OBJECT:
		vbp->vb_data_length = A_SizeOfObjectId(&(vbp->value_u.v_object));
		break;
	case VT_NOSUCHINS:
	case VT_NOSUCHOBJ:
	case VT_ENDOFMIB:
	case VT_EMPTY:
		vbp->vb_data_length = 0;
		break;
	case VT_IPADDRESS:
		vbp->vb_data_length = 4;
		break;
		/* We only include the following cases if v2 types are installed */
#if 1
	case VT_COUNTER64:
		vbp->vb_data_length = A_SizeOfUnsignedInt64(&(vbp->value_u.v_counter64));
		break;
#endif
	default:
		break;
	}

	vbp->vb_seq_size = vb_size + 1	/* The data tag is always 1 octet */
	                   + A_SizeOfLength(vbp->vb_data_length) + vbp->vb_data_length;

	return (1/* The sequence tag is always 1 octet */
	        + A_SizeOfLength(vbp->vb_seq_size) + vbp->vb_seq_size);
}

/****************************************************************************
NAME:  Set_Vbl_Sizes

PURPOSE:  Scan a VarBindList, setting the internal lengths and computing
          the total length.

PARAMETERS:
        VB_T *  The VarBindList structure to be scanned and set

RETURNS:  _UINT16     The number of octets the VarBindList contents would
                        use if ASN.1 encoded, including the list sequence
****************************************************************************/
_UINT16 Set_Vbl_Sizes(SNMP_PKT_T * rp)
{
	_INT16 i=0;
	VB_T *vbp;
	_UINT16 vblist_size=0;
	if(rp->pdu_type==TRAP_PDU)
		i=1;
	else
		i=0;
	for(;i<rp->pdu.vb_count;i++)
	{
		vbp=(VB_T *)(&(rp->pdu.vb_obj[i]));
		vblist_size += Get_Vb_Size(vbp);
	}
	rp->pdu.vbl_length = vblist_size;
	return (1/* Size of tag on VarBindList sequence */
			+ A_SizeOfLength(vblist_size) + vblist_size);
}
/****************************************************************************
NAME:  Set_Pdu_Size

PURPOSE:  Set the length of the pdu, this will cause the var bind list
          to be scanned and have it's lengths set as well

PARAMETERS:
        SNMP_PKT_T *   The packet to be scanned and set

RETURNS:  _UINT16     The number of octets the pdu contents would
                        use if ASN.1 encoded, including the pdu sequence
****************************************************************************/
_UINT16 Set_Pdu_Size(SNMP_PKT_T * rp)
{
	rp->pdu_length = 2 /* Tag and length of request_id (an integer) */
		+ A_SizeOfInt(rp->pdu.request_id) + 2	/* Tag and length of error_status (an integer) */
		+ A_SizeOfInt(rp->pdu.error_status) + 2	/* Tag and length of error_index (an integer) */
		+ A_SizeOfInt(rp->pdu.error_index) + Set_Vbl_Sizes(rp);
	return (1/* Size of tag on pdu sequence */
			+ A_SizeOfLength(rp->pdu_length) + rp->pdu_length);
}

/****************************************************************************
        BUFSIZE_FOR_NORMAL_PKT
****************************************************************************/
_UINT16 Bufsize_For_Normal_Pkt(SNMP_PKT_T * rp)
{
	_UINT16 alength;
	_UINT16 buffer_needed;
	alength = A_SizeOfOctetString(strlen(rp->community));

	rp->overall_length = Set_Pdu_Size(rp) + 2	/* Tag and length of snmp_version (an integer) */
		+ A_SizeOfInt(rp->snmp_version) + 1	/* Tag for the community octetstring */
		+ A_SizeOfLength(alength) + alength;

	buffer_needed = rp->overall_length + 1	/* Size of tag for overall Message sequence */
		+ A_SizeOfLength(rp->overall_length);

	return buffer_needed;
}
_UINT16 Bufsize_For_Trap_pkt(SNMP_PKT_T * rp)
{
	_UINT16 alength;

	rp->pdu_length =
	    2			/* Tag and length of request_id (an integer) */
		+ A_SizeOfObjectId(&(rp->pdu.vb_obj[0].vb_obj_id)) +

		2	/* Tag and length of net_address (a string) */
		+ 4/* Size of IP address in SMI */

		+ 2/* Tag and length of generic_trap (an integer) */
		+ A_SizeOfInt(rp->pdu.error_status) /*generic_trap*/

		+ 2	/* Tag and length of specific_trap (an integer) */
		+ A_SizeOfInt(rp->pdu.error_index)

		+2	/* Tag and length of trap_time_ticks (an uinteger) */
		+ A_SizeOfUnsignedInt(0)/*time tick*/

		+ Set_Vbl_Sizes(rp);

	alength = A_SizeOfOctetString(strlen(rp->community));

	rp->overall_length = 1		/* Size of tag on the PDU sequences */
		+ A_SizeOfLength(rp->pdu_length) + rp->pdu_length + 2	/* Tag and length of snmp_version (an integer) */
		+ A_SizeOfInt(rp->snmp_version) + 1	/* Tag for the community octetstring */
		+ A_SizeOfLength(alength) + alength;

	alength = rp->overall_length + 1	/* Size of tag for overall Message sequence */
		+ A_SizeOfLength(rp->overall_length);

	return alength;
}
/****************************************************************************
NAME:  SNMP_Encode_Var_Bind_List

PURPOSE:  Encode a VarBindList

PARAMETERS:
	 _UINT8 * Pointer to the packet
        VB_T *   The VarBindList to be encoded

RETURNS:  Nothing
****************************************************************************/
void SNMP_Encode_Var_Bind_List(SNMP_PKT_T * rp,_UINT8 *ebuffp)
{
	/*VB_T *vbp;*/
	_INT16 i=0;
	VB_T * vbp;
	/* Generate the VarBindList sequence header */
	(void)A_EncodeType(A_SEQUENCE, A_UNIVERSAL | A_CONSTRUCTOR,(_UINT8 *) ebuffp);
	(void)A_EncodeLength(rp->pdu.vbl_length, (_UINT8 *) ebuffp);
	if(rp->pdu_type==TRAP_PDU)
		i=1;
	else
		i=0;
	for(; i < rp->pdu.vb_count; i++)
	{
		vbp=(VB_T *)(&(rp->pdu.vb_obj[i]));
		(void)A_EncodeType(A_SEQUENCE, A_UNIVERSAL | A_CONSTRUCTOR,(_UINT8 *) ebuffp);
		(void)A_EncodeLength(vbp->vb_seq_size,  (_UINT8 *) ebuffp);
		(void)A_EncodeObjectId(A_OBJECTID, A_UNIVERSAL | A_PRIMITIVE,&(vbp->vb_obj_id),  (_UINT8 *) ebuffp);
	    	switch (vbp->vb_data_flags_n_type)
	    	{
		case VT_NUMBER:
			(void)A_EncodeInt(VT_NUMBER & ~A_IDCF_MASK,
						VT_NUMBER & A_IDCF_MASK,
						vbp->value_u.v_number,  (_UINT8 *) ebuffp);
			break;
		case VT_COUNTER:
			(void)A_EncodeUnsignedInt(VT_COUNTER & ~A_IDCF_MASK,
								VT_COUNTER & A_IDCF_MASK,
								vbp->value_u.v_counter,
								 (_UINT8 *) ebuffp);
			break;
		case VT_GAUGE:
			(void)A_EncodeUnsignedInt(VT_GAUGE & ~A_IDCF_MASK,
								VT_GAUGE & A_IDCF_MASK,
								vbp->value_u.v_counter,
								 (_UINT8 *) ebuffp);
			break;
		case VT_TIMETICKS:
			(void)A_EncodeUnsignedInt(VT_TIMETICKS & ~A_IDCF_MASK,
								VT_TIMETICKS & A_IDCF_MASK,
								vbp->value_u.v_counter,
								 (_UINT8 *) ebuffp);
			break;
		case VT_STRING:
			(void)A_EncodeOctetString(VT_STRING & ~A_IDCF_MASK,
								VT_STRING & A_IDCF_MASK,
								vbp->value_u.v_string,
								vbp->vb_data_length,
								 (_UINT8 *) ebuffp);
			break;
		case VT_OPAQUE:
			(void)A_EncodeOctetString(VT_OPAQUE & ~A_IDCF_MASK,
								VT_OPAQUE & A_IDCF_MASK,
								vbp->value_u.v_string,
								vbp->vb_data_length,
								 (_UINT8 *) ebuffp);
			break;
		case VT_OBJECT:
			(void)A_EncodeObjectId(A_OBJECTID, A_UNIVERSAL | A_PRIMITIVE,
							 &(vbp->value_u.v_object),
							  (_UINT8 *) ebuffp);
			break;
		case VT_EMPTY:
			(void)A_EncodeType(VT_EMPTY & ~A_IDCF_MASK,
						 VT_EMPTY & A_IDCF_MASK,  (_UINT8 *) ebuffp);
			(void)A_EncodeLength(0,  (_UINT8 *) ebuffp);
			break;
		case VT_IPADDRESS:
			(void)A_EncodeOctetString(VT_IPADDRESS & ~A_IDCF_MASK,
								VT_IPADDRESS & A_IDCF_MASK,
								vbp->value_u.v_network_address,
								4,  (_UINT8 *) ebuffp);
			break;

		case VT_NOSUCHOBJ:
		case VT_NOSUCHINS:
		case VT_ENDOFMIB:
			(void)A_EncodeType((_UINT16) (vbp->vb_data_flags_n_type & ~A_IDCF_MASK),
						 (_UINT8) (vbp->vb_data_flags_n_type & A_IDCF_MASK),
						  (_UINT8 *) ebuffp);
			(void)A_EncodeLength(0,  (_UINT8 *) ebuffp);
			break;

			/* We only do include the following cases if v2 types are installed */
		case VT_COUNTER64:
			(void)A_EncodeUnsignedInt64(VT_COUNTER64 & ~A_IDCF_MASK,
								  VT_COUNTER64 & A_IDCF_MASK,
								  &(vbp->value_u.v_counter64),
								   (_UINT8 *) ebuffp);
			break;
		default:
			break;
	}
	}
}
void SNMP_Encode_Trap_Pdu(SNMP_PKT_T * rp,_UINT8 *ebuffp)
{
	/* Generate the PDU header */
	A_EncodeType(rp->pdu_type, A_DEFAULT_SCOPE | A_CONSTRUCTOR, (_UINT8 *) ebuffp);
	A_EncodeLength(rp->pdu_length, (_UINT8 *) ebuffp);

	/* Encode enterprise */
	A_EncodeObjectId(A_OBJECTID, A_UNIVERSAL | A_PRIMITIVE,
					 (&(rp->pdu.vb_obj[0].vb_obj_id)), (_UINT8 *) ebuffp);
	/* Encode agent-addr */
	A_EncodeOctetString(VT_IPADDRESS & ~A_IDCF_MASK,
						VT_IPADDRESS & A_IDCF_MASK,
						&(rp->localip),4, (_UINT8 *) ebuffp);
	/* Encode generic-trap */
	A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE,
				rp->pdu.error_status, (_UINT8 *) ebuffp);
	/* Encode specific-trap */
	A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE,
				rp->pdu.error_index, (_UINT8 *) ebuffp);
	/* Encode time-stamp */
	A_EncodeUnsignedInt(VT_TIMETICKS & ~A_IDCF_MASK,
						VT_TIMETICKS & A_IDCF_MASK,
						0, (_UINT8 *) ebuffp);
	SNMP_Encode_Var_Bind_List(rp,ebuffp);
}
void SNMP_Encode_Normal_Pdu(SNMP_PKT_T * rp,_UINT8 *ebuffp)
{
	/* Generate the PDU header */
	(void)A_EncodeType(rp->pdu_type, A_DEFAULT_SCOPE | A_CONSTRUCTOR,  (_UINT8 *) ebuffp);
	(void)A_EncodeLength(rp->pdu_length, (_UINT8 *) ebuffp);
	/* Encode request-id */
	(void)A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE, rp->pdu.request_id,(_UINT8 *) ebuffp);
	/* Encode error-status */
	(void)A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE, rp->pdu.error_status,(_UINT8 *) ebuffp);
	/* Encode error-index */
	(void)A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE, rp->pdu.error_index,(_UINT8 *) ebuffp);
	(void)SNMP_Encode_Var_Bind_List(rp,ebuffp);
}

void SNMP_Encode_Common(_UINT8 * ebuffp,_UINT16 overall_length, _INT16 snmp_version, _UINT8 * community)
{
	/* Generate the Message sequence header */
	(void)A_EncodeType(A_SEQUENCE, A_UNIVERSAL | A_CONSTRUCTOR, (_UINT8 *) ebuffp);
	(void)A_EncodeLength(overall_length,(_UINT8 *) ebuffp);
	(void)A_EncodeInt(A_INTEGER, A_UNIVERSAL | A_PRIMITIVE,(_INT32)snmp_version,(_UINT8 *) ebuffp);
	(void)A_EncodeOctetString(A_OCTETSTRING, A_UNIVERSAL | A_PRIMITIVE,community,strlen(community),(_UINT8 *)ebuffp);
}

/****************************************************************************
NAME:  SNMP_Bufsize_For_Packet

PURPOSE:  Compute how much buffer space is needed to hold a packet if
          it were encoded.

PARAMETERS:
        SNMP_PKT_T *    SNMP Packet structure

RETURNS:  unsigned int  The buffer size required.
          0 in the case that the packet has a version that the code doesn't
          understand, either a completely bad version or one that the code
          hasn't been compiled for.

NOTE:   This routine does not account for any size differences which may
        occur due to any special authentication encoding.
****************************************************************************/
_UINT16 SNMP_Bufsize_For_Packet(SNMP_PKT_T * rp)
{
	if(rp->pdu_type != TRAP_PDU)
		return Bufsize_For_Normal_Pkt(rp);
	else
		return Bufsize_For_Trap_pkt(rp);
	return (0);
}

/****************************************************************************
NAME:  SNMP_Encode_Pkt_With_Siz

PURPOSE:  Encode an SNMP packet, with the size as one of the arguments.

PARAMETERS:
        SNMP_PKT_T *    SNMP Packet structure
	 _UINT8 * Pointer to the packet

RETURNS: TRUE        Packet processed without error
          FALSE            Error encountered during packet processing

         On a sucessful return, the ebuffer passed as a parameter will
         contain the encoded packet.

****************************************************************************/
_INT16 SNMP_Encode_Pkt_With_Siz(SNMP_PKT_T * rp,_UINT8 *ebuffp,_UINT16 need)
{
	/* Sanity check the space required variable */
	if(need == 0)
		return (-1);
	/* figure out what version we have and call the proper routines to
	 * do the encoding */
	(void)A_EncodeStart();
	switch (rp->snmp_version)
	{
		case SNMP_VERSION_1:
			/* encode the common header */
			SNMP_Encode_Common(ebuffp, rp->overall_length, rp->snmp_version, rp->community);
			/* encode the pdu */
			if(rp->pdu_type != TRAP_PDU)
				(void)SNMP_Encode_Normal_Pdu(rp, ebuffp);
			else
				(void)SNMP_Encode_Trap_Pdu(rp, ebuffp);
			return 0;
		case SNMP_VERSION_2:
			/* encode the common header */
			(void)SNMP_Encode_Common(ebuffp, rp->overall_length, rp->snmp_version, rp->community);
			/* encode the pdu */
			(void)SNMP_Encode_Normal_Pdu(rp, ebuffp);
			return 0;
		default:
			/* incorrect version number */
			return (-1);
	}
}
SNMP_PKT_T *SNMP_Create_Trap_V1(SNMP_PKT_T *rp,OBJ_ID_T *trapOid,_UINT32 specfic)
{
	rp->snmp_version = SNMP_VERSION_1;
	rp->pdu_type = TRAP_PDU;
	strcpy(rp->community,"public");
	rp->pdu.request_id = 0;
	rp->pdu.error_status = 6;
	rp->pdu.error_index = specfic;
	rp->pdu.vb_count=0;
	if(trapOid!=0)
	{
		rp->pdu.vb_count=1;
		rp->pdu.vb_obj[0].vb_obj_id.num_components=trapOid->num_components;
		memcpy(rp->pdu.vb_obj[0].vb_obj_id.component_list,trapOid->component_list,sizeof(trapOid->component_list));
	}
	else
	{
		rp->pdu.error_status = specfic;	
		rp->pdu.error_index = 0;
	}
}
#endif