Dear Snmp Community,
I have written a subagent (skeleton generated from subagent.m2c), where the
while loop is as follows:
/* you're main loop here... */
while(keep_running) {
//check and send traps
if (gTrapsAvailable) {
gTrapsAvailable = false;
//call traps
for (const auto error : gErrors) {
send_user_trap(error); //internally calls the send_v3trap()
api
}
}
/* if you use select(), see snmp_select_info() in snmp_api(3) */
/* --- OR --- */
agent_check_and_process(1); /* 0 == don't block */
//std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
My original problem was related to sending snmpv3 traps (send_v3trap()
api) *when
called from a different thread context*, then there were duplicate traps
sent.
/* excerpt from debug logs , total 4 times send_v3trap api called but 8
trap send)
2024-03-05 12:50:01 trap: send_trap -1 -1 iso.3.6.1.4.1.8072.3.2.10
2024-03-05 12:50:01 trap: sending trap type=12, version=193 to Local IPC:
/var/agentx/master
2024-03-05 12:50:01 agentx_build: packet built okay
test trap send_v3trap send
2024-03-05 12:50:01 trap: send_trap -1 -1 iso.3.6.1.4.1.8072.3.2.10
2024-03-05 12:50:01 trap: sending trap type=12, version=193 to Local IPC:
/var/agentx/master
2024-03-05 12:50:01 agentx_build: packet built okay
test trap send_v3trap send
2024-03-05 12:50:01 trap: send_trap -1 -1 iso.3.6.1.4.1.8072.3.2.10
2024-03-05 12:50:01 trap: sending trap type=12, version=193 to Local IPC:
/var/agentx/master
2024-03-05 12:50:01 agentx_build: packet built okay
test trap send_v3trap send
2024-03-05 12:50:01 trap: send_trap -1 -1 iso.3.6.1.4.1.8072.3.2.10
2024-03-05 12:50:01 trap: sending trap type=12, version=193 to Local IPC:
/var/agentx/master
2024-03-05 12:50:01 agentx_build: packet built okay
test trap send_v3trap send
2024-03-05 12:50:02 agentx_build: packet built okay
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: resending an inform for reqid=1933228917
2024-03-05 12:50:02 agentx_build: packet built okay
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: resending an inform for reqid=1933228919
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: received the inform response for reqid=1933228917
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: received the inform response for reqid=1933228919
2024-03-05 12:50:02 agentx_build: packet built okay
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: resending an inform for reqid=1933228921
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: received the inform response for reqid=1933228921
2024-03-05 12:50:02 agentx_build: packet built okay
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: resending an inform for reqid=1933228923
2024-03-05 12:50:02 trap: handle_inform_response for session UNKNOWN
2024-03-05 12:50:02 trap: received the inform response for reqid=1933228923
After reading some comments from the community my understanding is that
since snmp is not thread safe so the trap api must be called from subagent
thread context i.e. the while loop.
It solves my duplicate trap issue, but the problem now is that main thread
needs to wait for 15 seconds (ping timeout) when the
agent_check_and_process(1) unblocks and then send the traps.
I can run the agent_check_and_process(0) and make some sleep after, in
worst case introducing a delay of some x milliseconds
Therefore I want to ask 2 questions:
1. Is is possible to send the traps from different thread context (from
subagent), if yes then how ?
2. If not, then somehow is it possible to set the timeout on the
agent_check_and_process(int) api ? //I do not think decreasing the ping
timeout is a good idea
3. If also not possible to set the timeout, then is there some other way /
example like snmp_select_info ?
Cheers
Prankur
--
Cheers
Prankur
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