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chore: share RelayDnsPacket function code
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,88 @@ | ||
| package resolver | ||
|
|
||
| import ( | ||
| "context" | ||
| "encoding/binary" | ||
| "io" | ||
| "net" | ||
| "time" | ||
|
|
||
| "github.com/metacubex/mihomo/common/pool" | ||
|
|
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| D "github.com/miekg/dns" | ||
| ) | ||
|
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| const DefaultDnsReadTimeout = time.Second * 10 | ||
| const DefaultDnsRelayTimeout = time.Second * 5 | ||
|
|
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| const SafeDnsPacketSize = 2 * 1024 // safe size which is 1232 from https://dnsflagday.net/2020/, so 2048 is enough | ||
|
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| func RelayDnsConn(ctx context.Context, conn net.Conn) error { | ||
| buff := pool.Get(pool.UDPBufferSize) | ||
| defer func() { | ||
| _ = pool.Put(buff) | ||
| _ = conn.Close() | ||
| }() | ||
| for { | ||
| if conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout)) != nil { | ||
| break | ||
| } | ||
|
|
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| length := uint16(0) | ||
| if err := binary.Read(conn, binary.BigEndian, &length); err != nil { | ||
| break | ||
| } | ||
|
|
||
| if int(length) > len(buff) { | ||
| break | ||
| } | ||
|
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| n, err := io.ReadFull(conn, buff[:length]) | ||
| if err != nil { | ||
| break | ||
| } | ||
|
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| err = func() error { | ||
| ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout) | ||
| defer cancel() | ||
| inData := buff[:n] | ||
| msg, err := RelayDnsPacket(ctx, inData, buff) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| err = binary.Write(conn, binary.BigEndian, uint16(len(msg))) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| _, err = conn.Write(msg) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| return nil | ||
| }() | ||
| if err != nil { | ||
| return err | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func RelayDnsPacket(ctx context.Context, payload []byte, target []byte) ([]byte, error) { | ||
| msg := &D.Msg{} | ||
| if err := msg.Unpack(payload); err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| r, err := ServeMsg(ctx, msg) | ||
| if err != nil { | ||
| m := new(D.Msg) | ||
| m.SetRcode(msg, D.RcodeServerFailure) | ||
| return m.PackBuffer(target) | ||
| } | ||
|
|
||
| r.SetRcode(msg, r.Rcode) | ||
| r.Compress = true | ||
| return r.PackBuffer(target) | ||
| } |
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