netutil

Documentation

Overview

Package netutil contains network-related utilities common among dnsproxy packages.

TODO(a.garipov): Move improved versions of these into netutil in module golibs.

Index

• func ListenConfig() (lc *net.ListenConfig)
• func SortIPAddrs(addrs []net.IPAddr, preferIPv6 bool)
• func SortNetIPAddrs(addrs []netip.Addr, preferIPv6 bool)
• func UDPGetOOBSize() (oobSize int)
• func UDPRead(conn *net.UDPConn, buf []byte, udpOOBSize int) (n int, localIP net.IP, remoteAddr *net.UDPAddr, err error)
• func UDPSetOptions(c *net.UDPConn) (err error)
• func UDPWrite(data []byte, conn *net.UDPConn, remoteAddr *net.UDPAddr, localIP net.IP) (n int, err error)

Examples

• SortIPAddrs

Functions

func ListenConfig

func ListenConfig() (lc *net.ListenConfig)

ListenConfig returns the default net.ListenConfig used by the plain-DNS servers in this module.

TODO(a.garipov): Add tests.

TODO(a.garipov): Add an option to not set SO_REUSEPORT on Unix to prevent issues with OpenWrt.

See https://github.com/AdguardTeam/AdGuardHome/issues/5872.

TODO(a.garipov): DRY with AdGuard DNS when we can.

func SortIPAddrs

func SortIPAddrs(addrs []net.IPAddr, preferIPv6 bool)

SortIPAddrs sorts addrs in accordance with the protocol preferences. Invalid addresses are sorted near the end. Zones are ignored.

TODO(a.garipov): Use netip.Addr instead of net.IPAddr everywhere where this is called.

Example

package main

import (
	"fmt"
	"net"

	"github.com/AdguardTeam/dnsproxy/internal/netutil"
)

func main() {
	printAddrs := func(header string, addrs []net.IPAddr) {
		fmt.Printf("%s:\n", header)
		for i, a := range addrs {
			fmt.Printf("%d: %s\n", i+1, a.IP)
		}

		fmt.Println()
	}

	addrs := []net.IPAddr{{
		IP: net.ParseIP("1.2.3.4"),
	}, {
		IP: net.ParseIP("1.2.3.5"),
	}, {
		IP: net.ParseIP("2a00::1234"),
	}, {
		IP: net.ParseIP("2a00::1235"),
	}, {
		IP: nil,
	}}
	netutil.SortIPAddrs(addrs, false)
	printAddrs("IPv4 preferred", addrs)

	netutil.SortIPAddrs(addrs, true)
	printAddrs("IPv6 preferred", addrs)

}

Output:


IPv4 preferred:
1: 1.2.3.4
2: 1.2.3.5
3: 2a00::1234
4: 2a00::1235
5: <nil>

IPv6 preferred:
1: 2a00::1234
2: 2a00::1235
3: 1.2.3.4
4: 1.2.3.5
5: <nil>

func SortNetIPAddrs

func SortNetIPAddrs(addrs []netip.Addr, preferIPv6 bool)

SortNetIPAddrs sorts addrs in accordance with the protocol preferences. Invalid addresses are sorted near the end. Zones are ignored.

func UDPGetOOBSize

func UDPGetOOBSize() (oobSize int)

UDPGetOOBSize returns maximum size of the received OOB data.

func UDPRead

func UDPRead(
	conn *net.UDPConn,
	buf []byte,
	udpOOBSize int,
) (n int, localIP net.IP, remoteAddr *net.UDPAddr, err error)

UDPRead reads the message from conn using buf and receives a control-message payload of size udpOOBSize from it. It returns the number of bytes copied into buf and the source address of the message.

func UDPSetOptions

func UDPSetOptions(c *net.UDPConn) (err error)

UDPSetOptions sets flag options on a UDP socket to be able to receive the necessary OOB data.

func UDPWrite

func UDPWrite(
	data []byte,
	conn *net.UDPConn,
	remoteAddr *net.UDPAddr,
	localIP net.IP,
) (n int, err error)

UDPWrite writes the data to the remoteAddr using conn.