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Improve DNS truncate behavior

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世界 2024-02-14 20:42:58 +08:00
parent 5327aeaea4
commit 917514e09f
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GPG key ID: CD109927C34A63C4
1 changed files with 5 additions and 35 deletions
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40
outbound/dns.go
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@ -46,8 +46,8 @@ func (d *DNS) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.Pa
}
func (d *DNS) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
metadata.Destination = M.Socksaddr{}
defer conn.Close()
ctx = adapter.WithContext(ctx, &metadata)
for {
err := d.handleConnection(ctx, conn, metadata)
if err != nil {
@ -98,6 +98,7 @@ func (d *DNS) handleConnection(ctx context.Context, conn net.Conn, metadata adap
}
func (d *DNS) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
metadata.Destination = M.Socksaddr{}
var reader N.PacketReader = conn
var counters []N.CountFunc
var cachedPackets []*N.PacketBuffer
@ -111,14 +112,11 @@ func (d *DNS) NewPacketConnection(ctx context.Context, conn N.PacketConn, metada
}
}
if readWaiter, created := bufio.CreatePacketReadWaiter(reader); created {
readWaiter.InitializeReadWaiter(N.ReadWaitOptions{
MTU: dns.FixedPacketSize,
})
readWaiter.InitializeReadWaiter(N.ReadWaitOptions{})
return d.newPacketConnection(ctx, conn, readWaiter, counters, cachedPackets, metadata)
}
break
}
ctx = adapter.WithContext(ctx, &metadata)
fastClose, cancel := common.ContextWithCancelCause(ctx)
timeout := canceler.New(fastClose, cancel, C.DNSTimeout)
var group task.Group
@ -167,15 +165,11 @@ func (d *DNS) NewPacketConnection(ctx context.Context, conn N.PacketConn, metada
return err
}
timeout.Update()
responseBuffer := buf.NewPacket()
responseBuffer.Resize(1024, 0)
n, err := response.PackBuffer(responseBuffer.FreeBytes())
responseBuffer, err := dns.TruncateDNSMessage(&message, response, 1024)
if err != nil {
cancel(err)
responseBuffer.Release()
return err
}
responseBuffer.Truncate(len(n))
err = conn.WritePacket(responseBuffer, destination)
if err != nil {
cancel(err)
@ -241,16 +235,11 @@ func (d *DNS) newPacketConnection(ctx context.Context, conn N.PacketConn, readWa
return err
}
timeout.Update()
response = truncateDNSMessage(response, 512) // TODO: add an option to custom UDP buffer size
responseBuffer := buf.NewSize(dns.FixedPacketSize)
responseBuffer.Resize(1024, 0)
n, err := response.PackBuffer(responseBuffer.FreeBytes())
responseBuffer, err := dns.TruncateDNSMessage(&message, response, 1024)
if err != nil {
cancel(err)
responseBuffer.Release()
return err
}
responseBuffer.Truncate(len(n))
err = conn.WritePacket(responseBuffer, destination)
if err != nil {
cancel(err)
@ -264,22 +253,3 @@ func (d *DNS) newPacketConnection(ctx context.Context, conn N.PacketConn, readWa
})
return group.Run(fastClose)
}
func truncateDNSMessage(response *mDNS.Msg, maxLen int) *mDNS.Msg {
responseLen := response.Len()
if responseLen <= maxLen {
return response
}
newResponse := *response
response = &newResponse
for len(response.Answer) > 0 && responseLen > maxLen {
response.Answer = response.Answer[:len(response.Answer)-1]
response.Truncated = true
responseLen = response.Len()
}
if responseLen > maxLen {
response.Ns = nil
response.Extra = nil
}
return response
}