fix: increase udp buffer limit for dns server #8765
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Unix4ever
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- By default, github.com/miekg/dns uses `dns.MinMsgSize` for UDP messages, which is 512 bytes. This is too small for some DNS request/responses, and can cause truncation and errors. This change sets the buffer size to `dns.DefaultMsgSize` 4096 bytes, which is the maximum size of a dns packet payload per RFC 6891. - Another thing we do is increasing CoreDNS dns request payload limit to 4096 from the default 1232 bytes. - We also retry the request if the response is truncated or previous connection was closed. - And finally we properly handle the case where the response is larger than the client buffer size, and we return a truncated correct response. Closes siderolabs#8763 Signed-off-by: Dmitriy Matrenichev <dmitry.matrenichev@siderolabs.com>
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By default, github.com/miekg/dns uses
dns.MinMsgSizefor UDP messages, which is 512 bytes. This is too small for some DNS request/responses, and can cause truncation and errors. This change sets the buffer size todns.DefaultMsgSize4096 bytes, which is the maximum size of a dns packet payload per RFC 6891.Also increase CoreDNS dns request payload limit to 4096 from the default 1232 bytes.
For #8763