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Merge pull request #87 from matsuyoshi30/feature/add-dns-resolver
Add support for resolvers option
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,31 @@ | ||
| package attacker | ||
|
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| import ( | ||
| "context" | ||
| "net" | ||
| "sync/atomic" | ||
| "time" | ||
| ) | ||
|
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| type resolver struct { | ||
| addrs []string | ||
| idx uint64 | ||
| } | ||
|
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| func NewResolver(addrs []string) *net.Resolver { | ||
| r := &resolver{addrs: addrs} | ||
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| return &net.Resolver{ | ||
| PreferGo: true, | ||
| Dial: func(ctx context.Context, network, address string) (net.Conn, error) { | ||
| d := net.Dialer{ | ||
| Timeout: time.Millisecond * time.Duration(2000), | ||
| } | ||
| return d.DialContext(ctx, network, r.address()) | ||
| }, | ||
| } | ||
| } | ||
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| func (r *resolver) address() string { | ||
| return r.addrs[atomic.AddUint64(&r.idx, 1)%uint64(len(r.addrs))] | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| package attacker | ||
|
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| import ( | ||
| "fmt" | ||
| "io/ioutil" | ||
| "net" | ||
| "net/http" | ||
| "net/http/httptest" | ||
| "net/url" | ||
| "strings" | ||
| "testing" | ||
| "time" | ||
|
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| "github.com/miekg/dns" | ||
| ) | ||
|
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| const ( | ||
| testDomain = "test.notadomain" | ||
| DNSServerAddress = "127.0.0.1" | ||
| message = "Test Server" | ||
| ) | ||
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| func TestNewResolver(t *testing.T) { | ||
| done := make(chan struct{}) // for ensuring ds.PacketConn is not nil | ||
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| // prepare custom DNS server | ||
| dns.HandleFunc(".", handleRequest) | ||
| ds := dns.Server{ | ||
| Addr: DNSServerAddress + ":0", | ||
| Net: "udp", | ||
| ReadTimeout: time.Millisecond * time.Duration(2000), | ||
| WriteTimeout: time.Millisecond * time.Duration(2000), | ||
| NotifyStartedFunc: func() { close(done) }, | ||
| } | ||
|
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| go func() { | ||
| if err := ds.ListenAndServe(); err != nil { | ||
| t.Logf("got error during dns ListenAndServe: %s", err) | ||
| } | ||
| }() | ||
| defer func() { | ||
| _ = ds.Shutdown() | ||
| }() | ||
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| <-done | ||
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| net.DefaultResolver = NewResolver([]string{ds.PacketConn.LocalAddr().String()}) | ||
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| // test server for name resolution | ||
| ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | ||
| fmt.Fprintln(w, message) | ||
| })) | ||
| defer ts.Close() | ||
|
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| tsURL, _ := url.Parse(ts.URL) | ||
| _, port, _ := net.SplitHostPort(tsURL.Host) | ||
| tsURL.Host = net.JoinHostPort(testDomain, port) | ||
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| resp, err := http.Get(tsURL.String()) | ||
| if err != nil { | ||
| t.Fatalf("failed resolver round trip: %v", err) | ||
| } | ||
| defer resp.Body.Close() | ||
|
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| body, err := ioutil.ReadAll(resp.Body) | ||
| if err != nil { | ||
| t.Fatalf("failed to read respose body: %v", err) | ||
| } | ||
|
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| if strings.TrimSpace(string(body)) != message { | ||
| t.Errorf("reponse body mismatch, expected: '%s', but got '%s'", message, body) | ||
| } | ||
| } | ||
|
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| func handleRequest(w dns.ResponseWriter, r *dns.Msg) { | ||
| m := new(dns.Msg) | ||
| m.SetReply(r) | ||
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| m.Answer = []dns.RR{ | ||
| &dns.A{ | ||
| Hdr: dns.RR_Header{ | ||
| Name: r.Question[0].Name, | ||
| Rrtype: dns.TypeA, | ||
| Class: dns.ClassINET, | ||
| Ttl: 1, | ||
| }, | ||
| A: net.ParseIP(DNSServerAddress), | ||
| }, | ||
| } | ||
|
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||
| w.WriteMsg(m) | ||
| } |
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