udp_darwin.go

Documentation: golang.org/x/net/quic

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build go1.21 && darwin
     6  
     7  package quic
     8  
     9  import (
    10  	"encoding/binary"
    11  
    12  	"golang.org/x/sys/unix"
    13  )
    14  
    15  // See udp.go.
    16  const (
    17  	udpECNSupport              = true
    18  	udpInvalidLocalAddrIsError = true
    19  )
    20  
    21  // Confusingly, on Darwin the contents of the IP_TOS option differ depending on whether
    22  // it is used as an inbound or outbound cmsg.
    23  
    24  func parseIPTOS(b []byte) (ecnBits, bool) {
    25  	// Single byte. The low two bits are the ECN field.
    26  	if len(b) != 1 {
    27  		return 0, false
    28  	}
    29  	return ecnBits(b[0] & ecnMask), true
    30  }
    31  
    32  func appendCmsgECNv4(b []byte, ecn ecnBits) []byte {
    33  	// 32-bit integer.
    34  	// https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/netinet/in_tclass.c#L1062-L1073
    35  	b, data := appendCmsg(b, unix.IPPROTO_IP, unix.IP_TOS, 4)
    36  	binary.NativeEndian.PutUint32(data, uint32(ecn))
    37  	return b
    38  }
    39
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