gateway

README

gateway

A simple library for discovering the IP address of the default gateway.

Example:

package main

import (
    "fmt"

    "github.com/jackpal/gateway"
)

func main() {
    gateway, err := gateway.DiscoverGateway()
    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println("Gateway:", gateway.String())
   }
}

Provides implementations for:

• Darwin (macOS)
• Dragonfly
• FreeBSD
• Linux
• NetBSD
• OpenBSD
• Solaris and illumos
• Windows

Other platforms use an implementation that always returns an error.

Pull requests for other OSs happily considered!

Versions

v1.1.1

• Filter out On-link gateways. This is a Windows-specific feature. On-link gateways aren't currently connected to the Internet.

v1.1.0

• Add func DiscoverGateways() ([]net.IP, error). This func returns an array of gateways that contains at least one gateway. Otherwise returns an error.
• Update to go version 1.24.2
• Update dependencies to latest versions. (There was an x/net security warning.)

v1.0.16

Update x/net dependency. This was done to squelch a github security alert caused by depending upon an old version of x/net.

v1.0.15

Update dependencies to latest versions. This was done to squelch a github security alert caused by depending upon an old version of x/net. This is the first time I've updated module versions, the tests pass, so hopefully everything's good.

v1.0.14

• Fix panic when interface not set in Solaris netstat -rn output.

v1.0.13

• Add tools/check-cross-compile.sh to check that the code compiles for various OSs.
• Fix compilation errors exposed by tools/check-cross-compile.sh.

v1.0.12

• If there are multiple default gateways, Windows now returns the gateway with the lowest metric.
• Fix solaris build break. (In theory, IDK how to test this easily.)
• Upgrade to golang 1.21
• Upgrade golang.org/x/net version, makes dependabot happy. Probably was not any actual security issue because gateway doesn't use any of the APIs of golang.org/x/net that had security issues.

v1.0.11

• Implement DiscoverInterface for BSD-like OSes.

v1.0.10

• Fix non-BSD-based builds.

v1.0.9

• Add go.mod and go.sum files.
• Use "golang.org/x/net/route" to implement all BSD variants.
  • As a side effect this adds support for Dragonfly and NetBSD.
• Add example to README.
• Remove broken continuous integration.

v1.0.8

• Add support for OpenBSD
• Linux parser now supports gateways with an IP address of 0.0.0.0
• Fall back to netstat on darwin systems if route fails.
• Simplify Linux /proc/net/route parsers.

Documentation

Overview

Code generated by go generate

Index

• func DiscoverGateway() (ip net.IP, err error)
• func DiscoverGateways() (ips []net.IP, err error)
• func DiscoverInterface() (ip net.IP, err error)
• type ErrCantParse
  • func (*ErrCantParse) Error() string
• type ErrInvalidRouteFileFormat
  • func (e *ErrInvalidRouteFileFormat) Error() string
• type ErrNoGateway
  • func (*ErrNoGateway) Error() string
• type ErrNotImplemented
  • func (*ErrNotImplemented) Error() string

Examples

• DiscoverGateway

Functions

func DiscoverGateway

func DiscoverGateway() (ip net.IP, err error)

DiscoverGateway is the OS independent function to get the default gateway

Example

gateway, err := DiscoverGateway()
if err != nil {
	fmt.Println(err)
} else {
	fmt.Println("Gateway:", gateway.String())
}

func DiscoverGateways

func DiscoverGateways() (ips []net.IP, err error)

DiscoverGateways is the OS independent function to get all gateways. If err is nil, then ips is guarenteed to have at least one element.

func DiscoverInterface

func DiscoverInterface() (ip net.IP, err error)

DiscoverInterface is the OS independent function to call to get the default network interface IP that uses the default gateway

Types

type ErrCantParse

type ErrCantParse struct{}

ErrCantParse is returned if the route table is garbage.

func (*ErrCantParse) Error

func (*ErrCantParse) Error() string

type ErrInvalidRouteFileFormat

type ErrInvalidRouteFileFormat struct {
	// contains filtered or unexported fields
}

ErrInvalidRouteFileFormat is returned if the format of /proc/net/route is unexpected on Linux systems. Please raise an issue.

func (*ErrInvalidRouteFileFormat) Error

func (e *ErrInvalidRouteFileFormat) Error() string

type ErrNoGateway

type ErrNoGateway struct{}

ErrNoGateway is returned if a valid gateway entry was not found in the route table.

func (*ErrNoGateway) Error

func (*ErrNoGateway) Error() string

type ErrNotImplemented

type ErrNotImplemented struct{}

ErrNotImplemented is returned if your operating system is not supported by this package. Please raise an issue to request support.

func (*ErrNotImplemented) Error

func (*ErrNotImplemented) Error() string