Documentation
¶
Overview ¶
Command query resolves a single name against a recursive resolver over UDP and prints the response.
It demonstrates the complete client half of the dnsmsg package: building a query with dnsmsg.Message.SetQuestion, advertising an EDNS(0) buffer size, encoding with dnsmsg.Message.Pack, writing the result to a UDP socket as one datagram, decoding the reply with dnsmsg.Unpack, and reading the answer section through a type switch on dnsmsg.RData.
Two details in here are easy to leave out and expensive to leave out. The query ID comes from crypto/rand rather than a counter, and every datagram that arrives is checked against both that ID and the question that was asked before it is accepted. A resolver that skips either check accepts the first forged packet an off-path attacker sends.
Usage:
query [flags] <name> query example.com query -type MX -server 9.9.9.9 example.com query -type HTTPS -dnssec cloudflare.com query -hex -type CAA google.com
Source Files