Repository: louislam/uptime-kuma
File: server/monitor-types/snmp.js (JavaScript)

Code before:
            });

            const varbinds = await new Promise((resolve, reject) => {
                session.get([ monitor.snmpOid ], (error, varbinds) => {
                    error ? reject(error) : resolve(varbinds);
                });
            });
            log.debug("monitor", `SNMP: Received varbinds (Type: ${snmp.ObjectType[varbinds[0].type]} Value: ${varbinds[0].value})`);

            if (varbinds.length === 0) {
                throw new Error(`No varbinds returned from SNMP session (OID: ${monitor.snmpOid})`);
            }

            if (varbinds[0].type === snmp.ObjectType.NoSuchInstance) {
                throw new Error(`The SNMP query returned that no instance exists for OID ${monitor.snmpOid}`);
            }

            // We restrict querying to one OID per monitor, therefore `varbinds[0]` will always contain the value we're interested in.
            const value = varbinds[0].value;

            const { status, response } = await evaluateJsonQuery(value, monitor.jsonPath, monitor.jsonPathOperator, monitor.expectedValue);

            heartbeat.status = status ? UP : DOWN;
            heartbeat.msg = `SNMP value ${status ? "passes" : "does not pass"} `;
            heartbeat.msg += `comparison: ${response} ${monitor.jsonPathOperator} ${monitor.expectedValue}.`;

        } catch (err) {
            heartbeat.status = DOWN;
            heartbeat.msg = `Error: ${err.message}`;
        } finally {
            if (session) {
                session.close();
            }
        }
    }
}

module.exports = {
    SNMPMonitorType,
};


Review comment (suggestion):
Otherwise the retry-logic in the try-catch block is not triggered

```suggestion
            if (status) {
                bean.status = UP; 
                bean.msg = `JSON query passes (comparing ${response} ${this.jsonPathOperator} ${this.expectedValue})`
            } else {
                throw new Error(`JSON query does not pass (comparing ${response} ${this.jsonPathOperator} ${this.expectedValue})`);
            }
```

Code after:
            const varbinds = await new Promise((resolve, reject) => {
                session.get([ monitor.snmpOid ], (error, varbinds) => {
                    error ? reject(error) : resolve(varbinds);
                });
            });
            log.debug("monitor", `SNMP: Received varbinds (Type: ${snmp.ObjectType[varbinds[0].type]} Value: ${varbinds[0].value})`);

            if (varbinds.length === 0) {
                throw new Error(`No varbinds returned from SNMP session (OID: ${monitor.snmpOid})`);
            }

            if (varbinds[0].type === snmp.ObjectType.NoSuchInstance) {
                throw new Error(`The SNMP query returned that no instance exists for OID ${monitor.snmpOid}`);
            }

            // We restrict querying to one OID per monitor, therefore `varbinds[0]` will always contain the value we're interested in.
            const value = varbinds[0].value;

            const { status, response } = await evaluateJsonQuery(value, monitor.jsonPath, monitor.jsonPathOperator, monitor.expectedValue);

            if (status) {
                heartbeat.status = UP;
                heartbeat.msg = `JSON query passes (comparing ${response} ${monitor.jsonPathOperator} ${monitor.expectedValue})`;
            } else {
                throw new Error(`JSON query does not pass (comparing ${response} ${monitor.jsonPathOperator} ${monitor.expectedValue})`);
            }
        } finally {
            if (session) {
                session.close();
            }
        }
    }
}

module.exports = {
    SNMPMonitorType,
};