Refactor dns server to pass configurables to handlers in a struct. #1334

tomwilkie · 2015-08-19T17:02:28Z

Also ignore EDNS on tcp requests. Fixes #1332

nameserver/dns.go

@@ -286,9 +289,16 @@ func truncateResponse(response *dns.Msg, maxSize int) {
 	response.Truncated = true
 }

-func getMaxResponseSize(req *dns.Msg, defaultMaxResponseSize int) int {
+func (h *handler) responseTooBig(request, response *dns.Msg) bool {
+	if len(response.Answer) <= 1 || h.maxResponseSize <= 0 {


rade · 2015-08-20T08:30:58Z

I changed the mux to an embedded struct, so the handler is now a ServeMux. What do you think?

It's not what I would have done. Handlers don't need to know about the ServeMux. Let alone do they need to be be a ServeMux. It's unnecessary coupling.

rade · 2015-08-20T08:38:10Z

i.e.

func (d *DNSServer) addHandlers(mux *dns.ServeMux, client *dns.Client, defaultMaxResponseSize int) {
    h := &handler{
        DNSServer:       d,
        maxResponseSize: defaultMaxResponseSize,
        client:          client,
    }
    mux.HandleFunc(d.domain, h.handleLocal)
    mux.HandleFunc(reverseDNSdomain, h.handleReverse)
    mux.HandleFunc(topDomain, h.handleRecursive)
}

and

mux := dns.NewServeMux()
d.addHandlers(mux, d.udpClient, minUDPSize)
udpServer := &dns.Server{PacketConn: udpListener, Handler: mux}

rade · 2015-08-20T08:39:32Z

or

udpServer := &dns.Server{PacketConn: udpListener, Handler: dns.NewServeMux()}
d.addHandlers(udpServer.Handler, d.udpClient, minUDPSize)

test/295_dns_large_response_test.sh

 assert_raises "exec_on $HOST1 c0 dig MX $NAME | grep -q 'status: NXDOMAIN'"

+check() {
+    M=$(exec_on $HOST1 c0 dig +short $@ $NAME A | grep -v ';;' | wc -l)
+    assert_raises "test $M -eq $N"


nameserver/dns.go

+		return false
+	}
+	return response.Len() > h.getMaxResponseSize(request)
+}


Also ignore EDNS on tcp requests. Fixes #1332 Also fixes the case where recursive dns entries would be considered too big and compressed when using TCP.

tomwilkie · 2015-08-21T09:00:33Z

Superseded #1344

inercia added the in progress label Aug 19, 2015

tomwilkie force-pushed the 1332-big-dns-response branch from f121737 to c485b1e Compare August 19, 2015 17:09

tomwilkie reviewed Aug 19, 2015
View reviewed changes

rade reviewed Aug 20, 2015
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test/295_dns_large_response_test.sh

assert_raises "exec_on $HOST1 c0 dig MX $NAME | grep -q 'status: NXDOMAIN'"

check() {

M=$(exec_on $HOST1 c0 dig +short $@ $NAME A | grep -v ';;' | wc -l)

assert_raises "test $M -eq $N"

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rade removed the in progress label Aug 20, 2015

rade reviewed Aug 20, 2015
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nameserver/dns.go

return false

}

return response.Len() > h.getMaxResponseSize(request)

}

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Refactor dns server to pass configurables to handlers in a struct.

52d88a1

Also ignore EDNS on tcp requests. Fixes #1332 Also fixes the case where recursive dns entries would be considered too big and compressed when using TCP.

rade force-pushed the 1332-big-dns-response branch from 6824487 to 52d88a1 Compare August 20, 2015 16:49

rade self-assigned this Aug 20, 2015

rade mentioned this pull request Aug 20, 2015

Refactor dns handlers #1344

Merged

tomwilkie closed this Aug 21, 2015

rade deleted the 1332-big-dns-response branch August 21, 2015 13:03

rade modified the milestone: 1.1.0 Aug 29, 2015

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Refactor dns server to pass configurables to handlers in a struct. #1334

Refactor dns server to pass configurables to handlers in a struct. #1334

tomwilkie commented Aug 19, 2015

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rade commented Aug 20, 2015

rade commented Aug 20, 2015

rade commented Aug 20, 2015

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tomwilkie commented Aug 21, 2015

Refactor dns server to pass configurables to handlers in a struct. #1334

Refactor dns server to pass configurables to handlers in a struct. #1334

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tomwilkie commented Aug 19, 2015

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rade commented Aug 20, 2015

rade commented Aug 20, 2015

rade commented Aug 20, 2015

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tomwilkie commented Aug 21, 2015