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package resolver
import (
"context"
"io"
"net/netip"
"testing"
"time"
"codeberg.org/miekg/dns"
"codeberg.org/miekg/dns/dnsutil"
"codeberg.org/miekg/dns/rdata"
)
func startTestServer(t *testing.T, addr string, handler dns.Handler) *dns.Server {
t.Helper()
ready := make(chan struct{})
srv := &dns.Server{
Addr: addr,
Net: "udp",
Handler: handler,
UDPSize: 4096,
NotifyStartedFunc: func(ctx context.Context) {
close(ready)
},
}
go func() {
_ = srv.ListenAndServe()
}()
<-ready
return srv
}
func TestLookupDirectAnswer(t *testing.T) {
srv := startTestServer(t, "127.0.0.1:15353",
dns.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, req *dns.Msg) {
resp := new(dns.Msg)
dnsutil.SetReply(resp, req)
resp.Authoritative = true
resp.Answer = append(resp.Answer, &dns.A{
Hdr: dns.Header{
Name: "example.com.",
Class: dns.ClassINET,
TTL: 60,
},
A: rdata.A{Addr: netip.AddrFrom4([4]byte{127, 0, 0, 1})},
})
io.Copy(w, resp)
}))
defer srv.Shutdown(context.Background())
time.Sleep(100 * time.Millisecond)
r := New(
WithRootAddresses([]string{"127.0.0.1:15353"}),
WithTimeout(500*time.Millisecond),
)
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
resp, err := r.Lookup(ctx, "example.com.", dns.TypeA)
if err != nil {
t.Fatalf("Lookup failed: %v", err)
}
if resp.Rcode != dns.RcodeSuccess {
t.Fatalf("expected NOERROR, got %d (%s)",
resp.Rcode, dns.RcodeToString[resp.Rcode])
}
if len(resp.Answer) != 1 {
t.Fatalf("expected 1 answer, got %d", len(resp.Answer))
}
a, ok := resp.Answer[0].(*dns.A)
if !ok {
t.Fatal("expected A record")
}
if a.A.Addr != netip.AddrFrom4([4]byte{127, 0, 0, 1}) {
t.Fatalf("expected 127.0.0.1, got %s", a.A.Addr)
}
}
func TestLookupNXDOMAIN(t *testing.T) {
srv := startTestServer(t, "127.0.0.1:15354",
dns.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, req *dns.Msg) {
resp := new(dns.Msg)
dnsutil.SetReply(resp, req)
resp.Rcode = dns.RcodeNameError
io.Copy(w, resp)
}))
defer srv.Shutdown(context.Background())
time.Sleep(100 * time.Millisecond)
r := New(
WithRootAddresses([]string{"127.0.0.1:15354"}),
WithTimeout(500*time.Millisecond),
)
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
resp, err := r.Lookup(ctx, "nonexistent.xyz.", dns.TypeA)
if err != nil {
t.Fatalf("Lookup failed: %v", err)
}
if resp.Rcode != dns.RcodeNameError {
t.Fatalf("expected NXDOMAIN, got %d", resp.Rcode)
}
}
func TestNextServersWithGlue(t *testing.T) {
msg := new(dns.Msg)
msg.Authoritative = false
msg.Ns = append(msg.Ns, &dns.NS{
Hdr: dns.Header{Name: "example.com.", Class: dns.ClassINET, TTL: 300},
NS: rdata.NS{Ns: "ns1.example.com."},
})
msg.Extra = append(msg.Extra, &dns.A{
Hdr: dns.Header{Name: "ns1.example.com.", Class: dns.ClassINET, TTL: 300},
A: rdata.A{Addr: netip.MustParseAddr("192.0.2.1")},
})
msg.Extra = append(msg.Extra, &dns.AAAA{
Hdr: dns.Header{Name: "ns1.example.com.", Class: dns.ClassINET, TTL: 300},
AAAA: rdata.AAAA{Addr: netip.MustParseAddr("2001:db8::1")},
})
r := &Resolver{}
addrs, err := r.nextServers(context.Background(), msg)
if err != nil {
t.Fatalf("nextServers failed: %v", err)
}
if len(addrs) != 1 || addrs[0] != "192.0.2.1" {
t.Fatalf("expected [192.0.2.1], got %v", addrs)
}
}
func TestNextServersNoGlue(t *testing.T) {
msg := new(dns.Msg)
msg.Authoritative = false
msg.Ns = append(msg.Ns, &dns.NS{
Hdr: dns.Header{Name: "example.com.", Class: dns.ClassINET, TTL: 300},
NS: rdata.NS{Ns: "ns1.example.com."},
})
r := &Resolver{maxDelegations: 30, timeout: time.Second, retries: 1}
_, err := r.nextServers(context.Background(), msg)
if err == nil {
t.Fatal("expected error when no glue and no roots")
}
}
func TestLookupCNAME(t *testing.T) {
callCount := 0
srv := startTestServer(t, "127.0.0.1:15355",
dns.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, req *dns.Msg) {
callCount++
resp := new(dns.Msg)
dnsutil.SetReply(resp, req)
resp.Authoritative = true
resp.Answer = append(resp.Answer,
&dns.CNAME{
Hdr: dns.Header{Name: "alias.example.com.", Class: dns.ClassINET, TTL: 60},
CNAME: rdata.CNAME{Target: "real.example.com."},
},
)
if callCount > 1 {
resp.Answer = append(resp.Answer,
&dns.A{
Hdr: dns.Header{Name: "real.example.com.", Class: dns.ClassINET, TTL: 60},
A: rdata.A{Addr: netip.AddrFrom4([4]byte{127, 0, 0, 1})},
},
)
}
io.Copy(w, resp)
}))
defer srv.Shutdown(context.Background())
time.Sleep(100 * time.Millisecond)
r := New(
WithRootAddresses([]string{"127.0.0.1:15355"}),
WithTimeout(time.Second),
)
ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
defer cancel()
resp, err := r.Lookup(ctx, "alias.example.com.", dns.TypeA)
if err != nil {
t.Fatalf("CNAME lookup failed: %v", err)
}
if resp.Rcode != dns.RcodeSuccess {
t.Fatalf("expected NOERROR, got %d", resp.Rcode)
}
hasCNAME := false
hasA := false
for _, rr := range resp.Answer {
if _, ok := rr.(*dns.CNAME); ok {
hasCNAME = true
}
if _, ok := rr.(*dns.A); ok {
hasA = true
}
}
if !hasCNAME {
t.Fatal("expected CNAME record in answer")
}
if !hasA {
t.Fatal("expected A record (CNAME target) in answer")
}
}
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