file

README

file

Name

file - enables serving zone data from an RFC 1035-style master file.

Description

The file plugin is used for an "old-style" DNS server. It serves from a preloaded file that exists on disk. If the zone file contains signatures (i.e. is signed, i.e. DNSSEC) correct DNSSEC answers are returned. Only NSEC is supported! If you use this setup you are responsible for resigning the zonefile.

Syntax

file DBFILE [ZONES...]

• DBFILE the database file to read and parse. If the path is relative the path from the root directive will be prepended to it.
• ZONES zones it should be authoritative for. If empty, the zones from the configuration block are used.

If you want to round robin A and AAAA responses look at the loadbalance plugin.

file DBFILE [ZONES... ] {
    transfer to ADDRESS...
    no_reload
    upstream [ADDRESS...]
}

• transfer enables zone transfers. It may be specified multiples times. To or from signals the direction. ADDRESS must be denoted in CIDR notation (127.0.0.1/32 etc.) or just as plain addresses. The special wildcard * means: the entire internet (only valid for 'transfer to'). When an address is specified a notify message will be send whenever the zone is reloaded.
• no_reload by default CoreDNS will try to reload a zone every minute and reloads if the SOA's serial has changed. This option disables that behavior.
• upstream defines upstream resolvers to be used resolve external names found (think CNAMEs) pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for normal authoritative serving you don't need or want to use this. ADDRESS can be an IP address, and IP:port or a string pointing to a file that is structured as /etc/resolv.conf. If no ADDRESS is given, CoreDNS will resolve CNAMEs against itself.

Examples

Load the example.org zone from example.org.signed and allow transfers to the internet, but send notifies to 10.240.1.1

example.org {
    file example.org.signed {
        transfer to *
        transfer to 10.240.1.1
    }
}

Or use a single zone file for multiple zones:

. {
    file example.org.signed example.org example.net {
        transfer to *
        transfer to 10.240.1.1
    }
}

Documentation

Overview

Package file implements a file backend.

Index

• Constants
• Variables
• type Apex
• type File
  • func (f File) Name() string
  • func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)
• type Result
• type Xfr
  • func (x Xfr) Name() string
  • func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)
• type Zone
  • func NewZone(name, file string) *Zone
  • func Parse(f io.Reader, origin, fileName string, serial int64) (*Zone, error)
  • func (z *Zone) All() []dns.RR
  • func (z *Zone) ClosestEncloser(qname string) (*tree.Elem, bool)
  • func (z *Zone) Copy() *Zone
  • func (z *Zone) CopyWithoutApex() *Zone
  • func (z *Zone) Delete(r dns.RR)
  • func (z *Zone) Glue(nsrrs []dns.RR, do bool) []dns.RR
  • func (z *Zone) Insert(r dns.RR) error
  • func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR, []dns.RR, Result)
  • func (z *Zone) Notify()
  • func (z *Zone) OnShutdown() error
  • func (z *Zone) Print()
  • func (z *Zone) Reload() error
  • func (z *Zone) SOASerialIfDefined() int64
  • func (z *Zone) TransferAllowed(state request.Request) bool
  • func (z *Zone) TransferIn() error
  • func (z *Zone) Update() error
• type Zones

Examples

• Zone.All

Constants

const MaxSerialIncrement uint32 = 2147483647

MaxSerialIncrement is the maximum difference between two serial numbers. If the difference between two serials is greater than this number, the smaller one is considered greater.

Variables

var TickTime = 1 * time.Minute

TickTime is the default time we use to reload zone. Exported to be tweaked in tests.

Types

type Apex

type Apex struct {
	SOA    *dns.SOA
	NS     []dns.RR
	SIGSOA []dns.RR
	SIGNS  []dns.RR
}

Apex contains the apex records of a zone: SOA, NS and their potential signatures.

type File

type File struct {
	Next  plugin.Handler
	Zones Zones
}

File is the plugin that reads zone data from disk.

func (File) Name

func (f File) Name() string

Name implements the Handler interface.

func (File) ServeDNS

func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the plugin.Handle interface.

type Result

type Result int

Result is the result of a Lookup

const (
	// Success is a successful lookup.
	Success Result = iota
	// NameError indicates a nameerror
	NameError
	// Delegation indicates the lookup resulted in a delegation.
	Delegation
	// NoData indicates the lookup resulted in a NODATA.
	NoData
	// ServerFailure indicates a server failure during the lookup.
	ServerFailure
)

type Xfr

type Xfr struct {
	*Zone
}

Xfr serves up an AXFR.

func (Xfr) Name

func (x Xfr) Name() string

Name implements the plugin.Hander interface.

func (Xfr) ServeDNS

func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the plugin.Handler interface.

type Zone

type Zone struct {
	*tree.Tree
	Apex Apex

	TransferTo   []string
	StartupOnce  sync.Once
	TransferFrom []string
	Expired      *bool

	NoReload bool

	Upstream upstream.Upstream // Upstream for looking up names during the resolution process
	// contains filtered or unexported fields
}

Zone defines a structure that contains all data related to a DNS zone.

func NewZone

func NewZone(name, file string) *Zone

NewZone returns a new zone.

func Parse

func Parse(f io.Reader, origin, fileName string, serial int64) (*Zone, error)

Parse parses the zone in filename and returns a new Zone or an error. If serial >= 0 it will reload the zone, if the SOA hasn't changed it returns an error indicating nothing was read.

func (*Zone) All

func (z *Zone) All() []dns.RR

All returns all records from the zone, the first record will be the SOA record, otionally followed by all RRSIG(SOA)s.

Example

zone, err := Parse(strings.NewReader(dbMiekNL), testzone, "stdin", 0)
if err != nil {
	return
}
records := zone.All()
for _, r := range records {
	fmt.Printf("%+v\n", r)
}
// Output
// xfr_test.go:15: miek.nl.	1800	IN	SOA	linode.atoom.net. miek.miek.nl. 1282630057 14400 3600 604800 14400
// xfr_test.go:15: www.miek.nl.	1800	IN	CNAME	a.miek.nl.
// xfr_test.go:15: miek.nl.	1800	IN	NS	linode.atoom.net.
// xfr_test.go:15: miek.nl.	1800	IN	NS	ns-ext.nlnetlabs.nl.
// xfr_test.go:15: miek.nl.	1800	IN	NS	omval.tednet.nl.
// xfr_test.go:15: miek.nl.	1800	IN	NS	ext.ns.whyscream.net.
// xfr_test.go:15: miek.nl.	1800	IN	MX	1 aspmx.l.google.com.
// xfr_test.go:15: miek.nl.	1800	IN	MX	5 alt1.aspmx.l.google.com.
// xfr_test.go:15: miek.nl.	1800	IN	MX	5 alt2.aspmx.l.google.com.
// xfr_test.go:15: miek.nl.	1800	IN	MX	10 aspmx2.googlemail.com.
// xfr_test.go:15: miek.nl.	1800	IN	MX	10 aspmx3.googlemail.com.
// xfr_test.go:15: miek.nl.	1800	IN	A	139.162.196.78
// xfr_test.go:15: miek.nl.	1800	IN	AAAA	2a01:7e00::f03c:91ff:fef1:6735
// xfr_test.go:15: archive.miek.nl.	1800	IN	CNAME	a.miek.nl.
// xfr_test.go:15: a.miek.nl.	1800	IN	A	139.162.196.78
// xfr_test.go:15: a.miek.nl.	1800	IN	AAAA	2a01:7e00::f03c:91ff:fef1:6735

func (*Zone) ClosestEncloser

func (z *Zone) ClosestEncloser(qname string) (*tree.Elem, bool)

ClosestEncloser returns the closest encloser for qname.

func (*Zone) Copy

func (z *Zone) Copy() *Zone

Copy copies a zone.

func (*Zone) CopyWithoutApex

func (z *Zone) CopyWithoutApex() *Zone

CopyWithoutApex copies zone z without the Apex records.

func (*Zone) Delete

func (z *Zone) Delete(r dns.RR)

Delete deletes r from z.

func (*Zone) Glue

func (z *Zone) Glue(nsrrs []dns.RR, do bool) []dns.RR

Glue returns any potential glue records for nsrrs.

func (*Zone) Insert

func (z *Zone) Insert(r dns.RR) error

Insert inserts r into z.

func (*Zone) Lookup

func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR, []dns.RR, Result)

Lookup looks up qname and qtype in the zone. When do is true DNSSEC records are included. Three sets of records are returned, one for the answer, one for authority and one for the additional section.

func (*Zone) Notify

func (z *Zone) Notify()

Notify will send notifies to all configured TransferTo IP addresses.

func (*Zone) OnShutdown

func (z *Zone) OnShutdown() error

OnShutdown shuts down any running go-routines for this zone.

func (*Zone) Print

func (z *Zone) Print()

Print prints the zone's tree to stdout.

func (*Zone) Reload

func (z *Zone) Reload() error

Reload reloads a zone when it is changed on disk. If z.NoRoload is true, no reloading will be done.

func (*Zone) SOASerialIfDefined

func (z *Zone) SOASerialIfDefined() int64

SOASerialIfDefined returns the SOA's serial if the zone has a SOA record in the Apex, or -1 otherwise.

func (*Zone) TransferAllowed

func (z *Zone) TransferAllowed(state request.Request) bool

TransferAllowed checks if incoming request for transferring the zone is allowed according to the ACLs.

func (*Zone) TransferIn

func (z *Zone) TransferIn() error

TransferIn retrieves the zone from the masters, parses it and sets it live.

func (*Zone) Update

func (z *Zone) Update() error

Update updates the secondary zone according to its SOA. It will run for the life time of the server and uses the SOA parameters. Every refresh it will check for a new SOA number. If that fails (for all server) it wil retry every retry interval. If the zone failed to transfer before the expire, the zone will be marked expired.

type Zones

type Zones struct {
	Z     map[string]*Zone // A map mapping zone (origin) to the Zone's data
	Names []string         // All the keys from the map Z as a string slice.
}

Zones maps zone names to a *Zone.