Add probe_dns_reply_truncated metric to the DNS prober - #1606
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The DNS prober exposed no response-header flags, so a truncated reply (response larger than the UDP buffer, TC bit set) looked like a generic failure. The *dns.Msg from client.Exchange already carries Truncated, so expose it as a gauge: 0 normally, 1 when the reply has the TC bit set. Signed-off-by: Emmanuel Yusufu Kimaswa <kimaswaemma36@gmail.com>
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The DNS prober exposes counts of answer/authority/additional records but no response-header flags. A truncated reply (response larger than the UDP buffer, TC bit set) currently looks like a generic failure with no diagnostic signal.
The
*dns.Msgfromclient.Exchangealready carries theTruncatedflag, so this adds aprobe_dns_reply_truncatedgauge: 0 normally, 1 when the reply has the TC bit set. That lets you tell a truncated reply apart from a real failure.Added
TestTruncatedDNSResponse(asserts 1 when the server sets TC), added the not-truncated case to the existing recursive test (asserts 0), and a CHANGELOG entry.Closes #1258