github.com/amnezia-vpn/amnezia-wg@v0.1.8/conn/controlfns.go (about)

     1  /* SPDX-License-Identifier: MIT
     2   *
     3   * Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
     4   */
     5  
     6  package conn
     7  
     8  import (
     9  	"net"
    10  	"syscall"
    11  )
    12  
    13  // UDP socket read/write buffer size (7MB). The value of 7MB is chosen as it is
    14  // the max supported by a default configuration of macOS. Some platforms will
    15  // silently clamp the value to other maximums, such as linux clamping to
    16  // net.core.{r,w}mem_max (see _linux.go for additional implementation that works
    17  // around this limitation)
    18  const socketBufferSize = 7 << 20
    19  
    20  // controlFn is the callback function signature from net.ListenConfig.Control.
    21  // It is used to apply platform specific configuration to the socket prior to
    22  // bind.
    23  type controlFn func(network, address string, c syscall.RawConn) error
    24  
    25  // controlFns is a list of functions that are called from the listen config
    26  // that can apply socket options.
    27  var controlFns = []controlFn{}
    28  
    29  // listenConfig returns a net.ListenConfig that applies the controlFns to the
    30  // socket prior to bind. This is used to apply socket buffer sizing and packet
    31  // information OOB configuration for sticky sockets.
    32  func listenConfig() *net.ListenConfig {
    33  	return &net.ListenConfig{
    34  		Control: func(network, address string, c syscall.RawConn) error {
    35  			for _, fn := range controlFns {
    36  				if err := fn(network, address, c); err != nil {
    37  					return err
    38  				}
    39  			}
    40  			return nil
    41  		},
    42  	}
    43  }