resolvconf

Documentation

Overview

Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf

Index

• Constants
• func GetNameservers(resolvConf []byte, kind int) []string
• func GetNameserversAsPrefix(resolvConf []byte) []netip.Prefix
• func GetOptions(resolvConf []byte) []string
• func GetSearchDomains(resolvConf []byte) []string
• func Path() string
• type File
  • func Build(path string, nameservers, dnsSearch, dnsOptions []string) (*File, error)
  • func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) (*File, error)
  • func Get() (*File, error)
  • func GetSpecific(path string) (*File, error)

Constants

const (
	IP = iota // IPv4 and IPv6
	IPv4
	IPv6
)

constants for the IP address type

Functions

func GetNameservers

func GetNameservers(resolvConf []byte, kind int) []string

GetNameservers returns nameservers (if any) listed in /etc/resolv.conf

func GetNameserversAsPrefix

func GetNameserversAsPrefix(resolvConf []byte) []netip.Prefix

GetNameserversAsPrefix returns nameservers (if any) listed in /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32")

func GetOptions

func GetOptions(resolvConf []byte) []string

GetOptions returns options (if any) listed in /etc/resolv.conf If more than one options line is encountered, only the contents of the last one is returned.

func GetSearchDomains

func GetSearchDomains(resolvConf []byte) []string

GetSearchDomains returns search domains (if any) listed in /etc/resolv.conf If more than one search line is encountered, only the contents of the last one is returned.

func Path

func Path() string

Types

type File

type File struct {
	Content []byte
	Hash    []byte
}

File contains the resolv.conf content and its hash

func Build

func Build(path string, nameservers, dnsSearch, dnsOptions []string) (*File, error)

Build generates and writes a configuration file to path containing a nameserver entry for every element in nameservers, a "search" entry for every element in dnsSearch, and an "options" entry for every element in dnsOptions. It returns a File containing the generated content and its (sha256) hash.

Note that the resolv.conf file is written, but the hash file is not.

func FilterResolvDNS

func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) (*File, error)

FilterResolvDNS cleans up the config in resolvConf. It has two main jobs:

1. It looks for localhost (127.*|::1) entries in the provided resolv.conf, removing local nameserver entries, and, if the resulting cleaned config has no defined nameservers left, adds default DNS entries
2. Given the caller provides the enable/disable state of IPv6, the filter code will remove all IPv6 nameservers if it is not enabled for containers

func Get

func Get() (*File, error)

Get returns the contents of /etc/resolv.conf and its hash

func GetSpecific

func GetSpecific(path string) (*File, error)

GetSpecific returns the contents of the user specified resolv.conf file and its hash