error_t snmpParseGetRequestPdu(SnmpAgentContext *context, const uint8_t *p, size_t length)
{
error_t error;
size_t n;
uint_t index;
SnmpVarBind var;
//Debug message
if(context->request.pduType == SNMP_PDU_GET_REQUEST)
{
TRACE_INFO("Parsing GetRequest-PDU...\r\n");
}
else if(context->request.pduType == SNMP_PDU_GET_NEXT_REQUEST)
{
TRACE_INFO("Parsing GetNextRequest-PDU...\r\n");
}
//Verify community name
error = snmpCheckCommunity(context, MIB_ACCESS_READ_ONLY);
//Wrong community name?
if(error) return error;
//Parse PDU header
error = snmpParsePduHeader(context, p, length);
//Failed to parse PDU header?
if(error) return error;
//Point to the first variable binding of the request
p = context->request.varBindList;
length = context->request.varBindListLen;
//Lock access to MIB bases
snmpLockMib(context);
//Loop through the list
for(index = 1; length > 0; index++)
{
//Parse variable binding
error = snmpParseVarBinding(p, length, &var, &n);
//Failed to parse variable binding?
if(error) break;
//GetRequest-PDU?
if(context->request.pduType == SNMP_PDU_GET_REQUEST)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
//GetNextRequest-PDU?
else
{
//Search the MIB for the next object
error = snmpGetNextObject(context, &var);
//SNMPv1 version?
if(context->version == SNMP_VERSION_1)
{
//Check status code
if(error == NO_ERROR)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
else
{
//Stop immediately
break;
}
}
//SNMPv2c version?
else
{
//Check status code
if(error == NO_ERROR)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
else if(error == ERROR_OBJECT_NOT_FOUND)
{
//The variable binding's value field is set to endOfMibView
var.class = ASN1_CLASS_CONTEXT_SPECIFIC;
var.type = SNMP_EXCEPTION_END_OF_MIB_VIEW;
var.valueLen = 0;
//Catch exception
error = NO_ERROR;
}
else
{
//Stop immediately
break;
}
}
}
error_t snmpProcessGetRequestPdu(SnmpAgentContext *context)
{
error_t error;
int_t index;
size_t n;
size_t length;
const uint8_t *p;
SnmpVarBind var;
//Check PDU type
if(context->request.pduType == SNMP_PDU_GET_REQUEST)
{
//Debug message
TRACE_INFO("Parsing GetRequest-PDU...\r\n");
//Total number of SNMP Get-Request PDUs which have been accepted and
//processed by the SNMP protocol entity
MIB2_INC_COUNTER32(mib2Base.snmpGroup.snmpInGetRequests, 1);
}
else if(context->request.pduType == SNMP_PDU_GET_NEXT_REQUEST)
{
//Debug message
TRACE_INFO("Parsing GetNextRequest-PDU...\r\n");
//Total number of SNMP Get-NextRequest PDUs which have been accepted
//and processed by the SNMP protocol entity
MIB2_INC_COUNTER32(mib2Base.snmpGroup.snmpInGetNexts, 1);
}
//Enforce access policy
if(context->user->mode != SNMP_ACCESS_READ_ONLY &&
context->user->mode != SNMP_ACCESS_READ_WRITE)
{
//Total number of SNMP messages delivered to the SNMP protocol entity
//which represented an SNMP operation which was not allowed by the SNMP
MIB2_INC_COUNTER32(mib2Base.snmpGroup.snmpInBadCommunityUses, 1);
//Report an error
return ERROR_ACCESS_DENIED;
}
//Initialize response message
error = snmpInitResponse(context);
//Any error to report?
if(error) return error;
//Point to the first variable binding of the request
p = context->request.varBindList;
length = context->request.varBindListLen;
//Lock access to MIB bases
snmpLockMib(context);
//Loop through the list
for(index = 1; length > 0; index++)
{
//Parse variable binding
error = snmpParseVarBinding(p, length, &var, &n);
//Failed to parse variable binding?
if(error) break;
//Make sure that the object identifier is valid
error = oidCheck(var.oid, var.oidLen);
//Invalid object identifier?
if(error) break;
//GetRequest-PDU?
if(context->request.pduType == SNMP_PDU_GET_REQUEST)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
//GetNextRequest-PDU?
else
{
//Search the MIB for the next object
error = snmpGetNextObject(context, &var);
//SNMPv1 version?
if(context->request.version == SNMP_VERSION_1)
{
//Check status code
if(error == NO_ERROR)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
else
{
//Stop immediately
break;
}
}
//SNMPv2c or SNMPv3 version?
else
{
//Check status code
if(error == NO_ERROR)
{
//Retrieve object value
error = snmpGetObjectValue(context, &var);
}
else if(error == ERROR_OBJECT_NOT_FOUND)
{
//The variable binding's value field is set to endOfMibView
var.class = ASN1_CLASS_CONTEXT_SPECIFIC;
var.type = SNMP_EXCEPTION_END_OF_MIB_VIEW;
var.valueLen = 0;
//Catch exception
error = NO_ERROR;
}
else
{
//Stop immediately
break;
}
}
}
