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 ParseSubnet(s string) (p netip.Prefix, err error)
• func PreferIPv4(a, b netip.Addr) (res int)
• func PreferIPv6(a, b netip.Addr) (res int)
• func SortNetIPAddrs(addrs []netip.Addr, preferIPv6 bool)
• func UDPGetOOBSize() (oobSize int)
• func UDPRead(conn *net.UDPConn, buf []byte, udpOOBSize int) (n int, localIP netip.Addr, remoteAddr *net.UDPAddr, err error)
• func UDPSetOptions(c *net.UDPConn) (err error)
• func UDPWrite(data []byte, conn *net.UDPConn, remoteAddr *net.UDPAddr, localIP netip.Addr) (n int, err error)

Examples

• SortNetIPAddrs

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 ParseSubnet

func ParseSubnet(s string) (p netip.Prefix, err error)

ParseSubnet parses s either as a CIDR prefix itself, or as an IP address, returning the corresponding single-IP CIDR prefix.

TODO(e.burkov): Move to golibs.

func PreferIPv4

func PreferIPv4(a, b netip.Addr) (res int)

PreferIPv4 compares two addresses, preferring IPv4 addresses over IPv6 ones. Invalid addresses are sorted near the end.

func PreferIPv6

func PreferIPv6(a, b netip.Addr) (res int)

PreferIPv6 compares two addresses, preferring IPv6 addresses over IPv4 ones. Invalid addresses are sorted near the end.

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.

Example

package main

import (
	"fmt"
	"net/netip"

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

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

		fmt.Println()
	}

	addrs := []netip.Addr{
		netip.MustParseAddr("1.2.3.4"),
		netip.MustParseAddr("1.2.3.5"),
		netip.MustParseAddr("2a00::1234"),
		netip.MustParseAddr("2a00::1235"),
		{},
	}
	netutil.SortNetIPAddrs(addrs, false)
	printAddrs("IPv4 preferred", addrs)

	netutil.SortNetIPAddrs(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: invalid IP

IPv6 preferred:
1: 2a00::1234
2: 2a00::1235
3: 1.2.3.4
4: 1.2.3.5
5: invalid IP

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 netip.Addr, 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.

TODO(s.chzhen): Consider using netip.Addr.

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 netip.Addr,
) (n int, err error)

UDPWrite writes the data to the remoteAddr using conn.

TODO(s.chzhen): Consider using netip.Addr.