dnsutil

Documentation

Overview

Package dnsutil contains DNS related helper functions.

Index

• Constants
• func DuplicateCNAME(r *dns.CNAME, records []dns.RR) bool
• func ExtractAddressFromReverse(reverseName string) string
• func IsReverse(name string) int
• func Join(labels []string) string
• func MinimalTTL(m *dns.Msg, mt response.Type) time.Duration
• func ParseHostPort(s, defaultPort string) (string, error)
• func ParseHostPortOrFile(s ...string) ([]string, error)
• func TrimZone(q string, z string) (string, error)

Constants

const (
	// IP4arpa is the reverse tree suffix for v4 IP addresses.
	IP4arpa = ".in-addr.arpa."
	// IP6arpa is the reverse tree suffix for v6 IP addresses.
	IP6arpa = ".ip6.arpa."
)

const (
	// MinimalDefaultTTL is the absolute lowest TTL we use in CoreDNS.
	MinimalDefaultTTL = 5 * time.Second
	// MaximumDefaulTTL is the maximum TTL was use on RRsets in CoreDNS.
	MaximumDefaulTTL = 1 * time.Hour
)

Functions

func DuplicateCNAME

func DuplicateCNAME(r *dns.CNAME, records []dns.RR) bool

DuplicateCNAME returns true if r already exists in records.

func ExtractAddressFromReverse

func ExtractAddressFromReverse(reverseName string) string

ExtractAddressFromReverse turns a standard PTR reverse record name into an IP address. This works for ipv4 or ipv6.

54.119.58.176.in-addr.arpa. becomes 176.58.119.54. If the conversion fails the empty string is returned.

func IsReverse

func IsReverse(name string) int

IsReverse returns 0 is name is not in a reverse zone. Anything > 0 indicates name is in a reverse zone. The returned integer will be 1 for in-addr.arpa. (IPv4) and 2 for ip6.arpa. (IPv6).

func Join

func Join(labels []string) string

Join joins labels to form a fully qualified domain name. If the last label is the root label it is ignored. Not other syntax checks are performed.

func MinimalTTL

func MinimalTTL(m *dns.Msg, mt response.Type) time.Duration

MinimalTTL scans the message returns the lowest TTL found taking into the response.Type of the message.

func ParseHostPort

func ParseHostPort(s, defaultPort string) (string, error)

ParseHostPort will check if the host part is a valid IP address, if the IP address is valid, but no port is found, defaultPort is added.

func ParseHostPortOrFile

func ParseHostPortOrFile(s ...string) ([]string, error)

ParseHostPortOrFile parses the strings in s, each string can either be a address, address:port or a filename. The address part is checked and the filename case a resolv.conf like file is parsed and the nameserver found are returned.

func TrimZone

func TrimZone(q string, z string) (string, error)

TrimZone removes the zone component from q. It returns the trimmed name or an error is zone is longer then qname. The trimmed name will be returned without a trailing dot.