Problem with snmptable, snmpwalk for a table with gaps in column ids

Discussion:

Aaron Young

2009-09-16 20:50:08 UTC

I've experienced an issue with 5.4.2.1 where my table has non-contiguous
column ids, and both snmpwalk and snmptable seem to stop at the gap.

i.e. (column ids 2,3,10)

snmptable -v2c -Ci -c public localhost:1616 mxOtherTable
SNMP table: MPATHIX-MIB::mxOtherTable

index mxOtherIdentity mxOtherState mxOtherErrorMsg
1 Joe's Chicken and Waffles ok ?
2 Sal's donut shoppe ok ?

If I use snmptable in GETNEXT or v1 mode it works fine.

An snmpwalk on the table oid will also stop at the gap:

snmpwalk -v2c -Ci -c public localhost:1616 mxOtherTable
MPATHIX-MIB::mxOtherTable = No Such Object available on this agent at this
OID
MPATHIX-MIB::mxOtherIdentity.1 = STRING: Joe's Chicken and Waffles
MPATHIX-MIB::mxOtherIdentity.2 = STRING: Sal's donut shoppe
MPATHIX-MIB::mxOtherState.1 = INTEGER: ok(1)
MPATHIX-MIB::mxOtherState.2 = INTEGER: ok(1)

This is in Solaris x86 built in 64-bit mode, communicating with snmpd
through agentx

Here's how I built my table:

static oid tableOid[] = { 1, 3, 6, 1, 4, 1, 8276, 1, 2, 1, 6 };

int defaultState = 1;

std::string tableName = "mxOtherTable";
static netsnmp_table_data_set* table
= netsnmp_create_table_data_set( tableName.c_str() );

// disallow SET
table->allow_creation = 0;

// add index
netsnmp_table_dataset_add_index( table, ASN_INTEGER );

// add columns
// column #
// type
// writable
// default value
// default value len

netsnmp_table_set_multi_add_default_row( table,
2, ASN_OCTET_STR, 0, NULL, 0,
3, ASN_INTEGER, 0, &defaultState, sizeof( defaultState ),
20, ASN_OCTET_STR, 0, NULL, 0,
0 );

netsnmp_handler_registration* regInfo
= netsnmp_create_handler_registration
( tableName.c_str(), NULL,
tableOid, OID_LENGTH(tableOid),
HANDLER_CAN_RWRITE );

netsnmp_register_table_data_set( regInfo, table, NULL);

netsnmp_register_auto_data_table( table, NULL );

// add
netsnmp_table_row* newRow = netsnmp_create_table_data_row();

int index = 1;
netsnmp_table_row_add_index( newRow, ASN_INTEGER,
&index, sizeof( index ) );

std::string identity = "Joe's Chicken and Waffles";
netsnmp_set_row_column (newRow, 2, ASN_OCTET_STR,
identity.c_str(), identity.length() );

netsnmp_set_row_column (newRow, 3, ASN_INTEGER,
reinterpret_cast<const char*>(&defaultState), sizeof( defaultState ) );

std::string errorMsg = "Waffle-lite";
netsnmp_set_row_column (newRow, 20, ASN_OCTET_STR,
errorMsg.c_str(), errorMsg.length() );

netsnmp_table_dataset_add_row( table, newRow );

// add
netsnmp_table_row* newRow2 = netsnmp_create_table_data_row();

index++;
netsnmp_table_row_add_index( newRow2, ASN_INTEGER,
&index, sizeof( index ) );

identity = "Sal's donut shoppe";
netsnmp_set_row_column (newRow2, 2, ASN_OCTET_STR,
identity.c_str(), identity.length() );

netsnmp_set_row_column (newRow2, 3, ASN_INTEGER,
reinterpret_cast<const char*>(&defaultState), sizeof( defaultState ) );

errorMsg = "full of donuts";
netsnmp_set_row_column (newRow2, 20, ASN_OCTET_STR,
errorMsg.c_str(), errorMsg.length() );

netsnmp_table_dataset_add_row( table, newRow2 );

Any ideas on what the problem may be?

-Aaron

Aaron Young

2009-09-16 22:56:32 UTC

Permalink

I tried using the valid_columns struct, didn't change anything:

netsnmp_table_set_multi_add_default_row( table,
2, ASN_OCTET_STR, 0, NULL, 0,
3, ASN_INTEGER, 0, &defaultState, sizeof( defaultState ),
20, ASN_OCTET_STR, 0, NULL, 0,
0 );

netsnmp_handler_registration* regInfo
= netsnmp_create_handler_registration
( tableName.c_str(), NULL,
tableOid, OID_LENGTH(tableOid),
HANDLER_CAN_RWRITE );

netsnmp_table_registration_info* table_info
= SNMP_MALLOC_TYPEDEF(netsnmp_table_registration_info);
table_info->indexes = snmp_clone_varbind(table->table->indexes_template);
table_info->min_column = 2;
table_info->max_column = 20;

table_info->valid_columns = SNMP_MALLOC_TYPEDEF(netsnmp_column_info);
table_info->valid_columns->isRange = 0;
table_info->valid_columns->list_count = 3;
table_info->valid_columns->details.list = static_cast<unsigned int*>(
malloc(sizeof(unsigned int)*3));
table_info->valid_columns->details.list[0] = 2;
table_info->valid_columns->details.list[1] = 3;
table_info->valid_columns->details.list[2] = 20;
table_info->valid_columns->next = 0;

netsnmp_register_table_data_set(regInfo, table, table_info);

netsnmp_register_auto_data_table( table, NULL );

-Aaron

Post by Aaron Young
I've experienced an issue with 5.4.2.1 where my table has non-contiguous
column ids, and both snmpwalk and snmptable seem to stop at the gap.
i.e. (column ids 2,3,10)
snmptable -v2c -Ci -c public localhost:1616 mxOtherTable
SNMP table: MPATHIX-MIB::mxOtherTable
index mxOtherIdentity mxOtherState mxOtherErrorMsg
1 Joe's Chicken and Waffles ok ?
2 Sal's donut shoppe ok ?
If I use snmptable in GETNEXT or v1 mode it works fine.
snmpwalk -v2c -Ci -c public localhost:1616 mxOtherTable
MPATHIX-MIB::mxOtherTable = No Such Object available on this agent at this
OID
MPATHIX-MIB::mxOtherIdentity.1 = STRING: Joe's Chicken and Waffles
MPATHIX-MIB::mxOtherIdentity.2 = STRING: Sal's donut shoppe
MPATHIX-MIB::mxOtherState.1 = INTEGER: ok(1)
MPATHIX-MIB::mxOtherState.2 = INTEGER: ok(1)
This is in Solaris x86 built in 64-bit mode, communicating with snmpd
through agentx
static oid tableOid[] = { 1, 3, 6, 1, 4, 1, 8276, 1, 2, 1, 6 };
int defaultState = 1;
std::string tableName = "mxOtherTable";
static netsnmp_table_data_set* table
= netsnmp_create_table_data_set( tableName.c_str() );
// disallow SET
table->allow_creation = 0;
// add index
netsnmp_table_dataset_add_index( table, ASN_INTEGER );
// add columns
// column #
// type
// writable
// default value
// default value len
netsnmp_table_set_multi_add_default_row( table,
2, ASN_OCTET_STR, 0, NULL, 0,
3, ASN_INTEGER, 0, &defaultState, sizeof( defaultState ),
20, ASN_OCTET_STR, 0, NULL, 0,
0 );
netsnmp_handler_registration* regInfo
= netsnmp_create_handler_registration
( tableName.c_str(), NULL,
tableOid, OID_LENGTH(tableOid),
HANDLER_CAN_RWRITE );
netsnmp_register_table_data_set( regInfo, table, NULL);
netsnmp_register_auto_data_table( table, NULL );
// add
netsnmp_table_row* newRow = netsnmp_create_table_data_row();
int index = 1;
netsnmp_table_row_add_index( newRow, ASN_INTEGER,
&index, sizeof( index ) );
std::string identity = "Joe's Chicken and Waffles";
netsnmp_set_row_column (newRow, 2, ASN_OCTET_STR,
identity.c_str(), identity.length() );
netsnmp_set_row_column (newRow, 3, ASN_INTEGER,
reinterpret_cast<const char*>(&defaultState), sizeof( defaultState ) );
std::string errorMsg = "Waffle-lite";
netsnmp_set_row_column (newRow, 20, ASN_OCTET_STR,
errorMsg.c_str(), errorMsg.length() );
netsnmp_table_dataset_add_row( table, newRow );
// add
netsnmp_table_row* newRow2 = netsnmp_create_table_data_row();
index++;
netsnmp_table_row_add_index( newRow2, ASN_INTEGER,
&index, sizeof( index ) );
identity = "Sal's donut shoppe";
netsnmp_set_row_column (newRow2, 2, ASN_OCTET_STR,
identity.c_str(), identity.length() );
netsnmp_set_row_column (newRow2, 3, ASN_INTEGER,
reinterpret_cast<const char*>(&defaultState), sizeof( defaultState ) );
errorMsg = "full of donuts";
netsnmp_set_row_column (newRow2, 20, ASN_OCTET_STR,
errorMsg.c_str(), errorMsg.length() );
netsnmp_table_dataset_add_row( table, newRow2 );
Any ideas on what the problem may be?
-Aaron
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Aaron Young

2009-10-06 16:46:23 UTC

Permalink

After much tracking down I believe I narrowed the problem down to an
assumption of contiguous indices in table_data.c.

Any getnext request on the last row of a column followed by a gap would
produce nonsense. This patch seems to fix the problem:

--- table_data.c.orig Tue Oct 6 12:33:16 2009
+++ table_data.c Tue Oct 6 12:36:22 2009
@@ -529,7 +529,9 @@
}
}
if (!row) {
- table_info->colnum++;
+ table_info->colnum =
+ netsnmp_closest_column(table_info->colnum + 1,
+ table_reg_info->valid_columns);
if (table_info->colnum <= table_reg_info->max_column) {
row = table->first_row;
}