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server.go
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server.go
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package main
import (
"log"
"mario/simple-dns-server/config"
"mario/simple-dns-server/dnsclient"
"mario/simple-dns-server/dnsparser"
"net"
"strings"
"github.com/miekg/dns"
)
func parseQuery(m *dns.Msg, remoteAddr net.Addr) {
for _, q := range m.Question {
q.Name = strings.ToLower(q.Name)
if config.Config.IsQueryLoggingEnabled {
go log.Printf("Query for %s from %s\n", q.Name, remoteAddr.String())
}
lastCharOfQNAME := q.Name[len(q.Name)-1:]
var qNameWithLastDot string = ""
var qNameWithoutLastDot string = ""
if lastCharOfQNAME == "." {
qNameWithLastDot = q.Name
qNameWithoutLastDot = strings.TrimSuffix(q.Name, ".")
} else {
qNameWithLastDot = q.Name + "."
qNameWithoutLastDot = q.Name
}
var didFindRecord bool = false
if q.Qtype == dns.TypeA {
didFindRecord = dnsparser.A(m, qNameWithLastDot, qNameWithoutLastDot)
}
if q.Qtype == dns.TypeSRV {
didFindRecord = dnsparser.SRV(m, qNameWithLastDot, qNameWithoutLastDot)
}
if q.Qtype == dns.TypeCNAME {
didFindRecord = dnsparser.CNAME(m, qNameWithLastDot, qNameWithoutLastDot)
}
if q.Qtype == dns.TypeNS {
didFindRecord = dnsparser.NS(m, qNameWithLastDot, qNameWithoutLastDot)
}
if !didFindRecord && config.Config.IsProcessUnstoredQueriesEnabled {
dnsClientResponse, err := dnsclient.DnsClientUsingQuestion(q, config.Config.ProcessUnstoredQueries_Server)
if err == nil {
m.Answer = dnsClientResponse.Answer
m.Rcode = dnsClientResponse.Rcode
}
}
if !didFindRecord && !config.Config.IsProcessUnstoredQueriesEnabled {
m.Rcode = dns.RcodeNameError
}
if didFindRecord {
m.Rcode = dns.RcodeSuccess // should be the default, but force setting it to make sure
}
}
}
func handleDnsRequest(w dns.ResponseWriter, r *dns.Msg) {
defer w.Close()
m := new(dns.Msg)
m.SetReply(r)
m.Compress = false
switch r.Opcode {
case dns.OpcodeQuery:
parseQuery(m, w.RemoteAddr())
}
w.WriteMsg(m)
}