Agent IP is not reflected properly in hsflowd.auto during Runtime

[koppulanagender-sys]

Hi Team,

Issue scenario:
At the start of the process, if a configured agent IP is available, it is used as the agent IP and the same IP is written to the hsflowd.auto file. However, if the configured IP is later no longer present on the device, the agent IP is reselected from the available IP addresses. This newly selected IP will not be reflected in the hsflowd.auto file.

Use Case:
I would like to determine the agent IP that hsflowd is using during runtime by referring to the hsflowd.auto file.

Please let me know if this is supported or if there is an alternative way to reliably identify the runtime agent IP.

hsflowd version used : 2.1.09-1

Thank you.

[sflow]

This is what is supposed to happen:

(1) If the selectAgentAddress() elects a new address it is supposed to trigger a called to installSFlowSettings() here:

host-sflow/src/Linux/hsflowd.c

Lines 919 to 926 in f64cf3f

	EVDebug(mod, 1, "agentAddressChanged=%s", agentAddressChanged ? "YES" : "NO");
	if(agentAddressChanged) {
	sfl_agent_set_address(sp->agent, &sp->agentIP);
	sfl_agent_set_address(sp->poll_agent, &sp->agentIP);
	// this incs the revision No so it causes the
	// output file to be rewritten below too.
	installSFlowSettings(sp, sp->sFlowSettings);
	}

(2) Which is supposed to cause the config revision number to get incremented here:

host-sflow/src/Linux/hsflowd.c

Line 1694 in f64cf3f

sp->revisionNo++;

(3) Which is turn should trigger a resync of the hsflowd.auto file here:

host-sflow/src/Linux/hsflowd.c

Lines 1100 to 1104 in f64cf3f

	// rewrite the output if the config has changed
	if(sp->outputRevisionNo != sp->revisionNo) {
	syncOutputFile(sp);
	sp->outputRevisionNo = sp->revisionNo;
	}

I'll try and recreate what you are seeing, but if you can run with logging or breakpoints to see why this sequence is not being followed then I would be grateful.

[koppulanagender-sys]

example conf file used :

sflow {
agent.cidr = 192.168.30.9/32
polling = 60
collector {
ip = 8.8.8.8
udpport = 6343
}
pcap {
dev = Port1
sampling = 50
}
}

1.In installSFlowSettings function, the revision number is not getting incremented and its returning before that.
https://github.com/sflow/host-sflow/blob/f64cf3f655e47fcea7dcefd224ce359b13d2ceb4/src/Linux/hsflowd.c : 1678

if(my_strequal(sp->sFlowSettings_str, settingsStr)) {
  // no change - don't increment the revision number
  // (which will mean that the file is not rewritten either)
  if(settingsStr)
my_free(settingsStr);
  return NO;
}

2.In sFlowSettingsString function before we copy the agentIP, we are checking for settings->agentIP.type to be 1, but here it is always 0 and agentIP is never copied, So even if there is a change in agentIP as the agentIP is never copied
my_strequal function returns true and revision number is never updated and thus syncOutputFile(sp) is never called.

https://github.com/sflow/host-sflow/blob/f64cf3f655e47fcea7dcefd224ce359b13d2ceb4/src/Linux/hsflowconfig.c + 638

  if(settings->agentIP.type)
UTStrBuf_printf(buf, "agentIP=%s\n", SFLAddress_print(&settings->agentIP, ipbuf, 63));
  if(settings->agentDevice)

Observed that settings->agentIP.type is set to 1 , only when we use agentIP in conf file, but in my case iam using agent.cidr.

log: here the log in installSFlowSettings shows agentIP is not included.

dbg3:mS=0 installSFlowSettings: <hostname=test>
sampling=400
header=128
datagram=1400
polling=60
collector=8.8.8.8

Do let me know if any specific logs i need share or anything i can help here in solving this...