"""
SNMPv3, auth: SHA, privacy: AES128
++++++++++++++++++++++++++++++++++

Send a SNMP GET request
* with SNMPv3 with user 'usr-sha-aes', SHA auth and AES128 privacy protocols
* over IPv4/UDP
* to an Agent at 127.0.0.1:161
* for an OID in tuple form

This script performs similar to the following Net-SNMP command:

| $ snmpget -v3 -l authPriv -u usr-sha-aes -a SHA -A authkey1 -x AES -X privkey1 -ObentU 127.0.0.1:161  1.3.6.1.2.1.1.1.0

"""  #
from pysnmp.entity import engine, config
from pysnmp.carrier.asyncio.dgram import udp
from pysnmp.entity.rfc3413 import cmdgen

# Create SNMP engine instance
snmpEngine = engine.SnmpEngine()

#
# SNMPv3/USM setup
#

# user: usr-sha-aes, auth: SHA, priv AES
config.add_v3_user(
    snmpEngine,
    "usr-sha-aes",
    config.USM_AUTH_HMAC96_SHA,
    "authkey1",
    config.USM_PRIV_CFB128_AES,
    "privkey1",
)
config.add_target_parameters(snmpEngine, "my-creds", "usr-sha-aes", "authPriv")

#
# Setup transport endpoint and bind it with security settings yielding
# a target name
#

# UDP/IPv4
config.add_transport(
    snmpEngine, udp.DOMAIN_NAME, udp.UdpAsyncioTransport().open_client_mode()
)
config.add_target_address(
    snmpEngine, "my-router", udp.DOMAIN_NAME, ("127.0.0.1", 161), "my-creds"
)


# Error/response receiver
# noinspection PyUnusedLocal,PyUnusedLocal,PyUnusedLocal
def cbFun(
    snmpEngine,
    sendRequestHandle,
    errorIndication,
    errorStatus,
    errorIndex,
    varBinds,
    cbCtx,
):
    if errorIndication:
        print(errorIndication)
    elif errorStatus:
        print(
            f"{errorStatus.prettyPrint()} at {varBinds[int(errorIndex) - 1][0] if errorIndex else '?'}"
        )
    else:
        for oid, val in varBinds:
            print(f"{oid.prettyPrint()} = {val.prettyPrint()}")


# Prepare and send a request message
cmdgen.GetCommandGenerator().send_varbinds(
    snmpEngine,
    "my-router",
    None,
    "",  # contextEngineId, contextName
    [((1, 3, 6, 1, 2, 1, 1, 1, 0), None)],
    cbFun,
)

# Run I/O dispatcher which would send pending queries and process responses
snmpEngine.oepn_dispatcher(3)

snmpEngine.close_dispatcher()
