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Zoltán Papp
91d4f61284
validateTag checked tag names against the per-measurement allowlist but only bounded the value length, so the peer_id tag was free-form text up to 64 bytes and could differ from the X-Peer-ID header the request was accepted with. Tie the two together: the tag value must equal the header value. Since the header is already checked to be 16 hex characters, this transitively constrains the tag to the same shape. Every client sends the same value in both places (metrics.go feeds agentInfo.peerID to both push.SetPeerID and the body tags), so well-behaved clients are unaffected. The mismatch is rejected rather than silently overwritten: rewriting the value would re-serialize caller-controlled text back into line protocol and would hide misbehaving senders instead of surfacing them. Rejection also matches the other input validation failures in the same handler, which all return 400. This narrows the value space of the peer_id tag but does not by itself bound InfluxDB series cardinality: a sender that puts the same arbitrary 16 hex characters in both the header and the body still passes. Limiting that needs a per-source rate limit in front of the service.