plugin

package
v1.4.0 Latest Latest
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 Go to latest Published: Mar 3, 2019 License: Apache-2.0 Imports: 14 Imported by: 0

Documentation

Overview

Package plugin provides some types and functions common among plugin.

Index

Constants

View Source 
const Namespace = "coredns"

Namespace is the namespace used for the metrics.

Variables

View Source 
var ErrOnce = errors.New("this plugin can only be used once per Server Block")

ErrOnce is returned when a plugin doesn't support multiple setups per server.

View Source 
var TimeBuckets = prometheus.ExponentialBuckets(0.00025, 2, 16) // from 0.25ms to 8 seconds

TimeBuckets is based on Prometheus client_golang prometheus.DefBuckets

Functions

func A 

func A(b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error)

A returns A records from Backend or an error.

func AAAA 

func AAAA(b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error)

AAAA returns AAAA records from Backend or an error.

func BackendError 

func BackendError(b ServiceBackend, zone string, rcode int, state request.Request, err error, opt Options) (int, error)

BackendError writes an error response to the client.

func CNAME 

func CNAME(b ServiceBackend, zone string, state request.Request, opt Options) (records []dns.RR, err error)

CNAME returns CNAME records from the backend or an error.

func ClientWrite 

func ClientWrite(rcode int) bool

ClientWrite returns true if the response has been written to the client. Each plugin to adhire to this protocol.

func Error 

func Error(name string, err error) error

Error returns err with 'plugin/name: ' prefixed to it.

func MX 

func MX(b ServiceBackend, zone string, state request.Request, opt Options) (records, extra []dns.RR, err error)

MX returns MX records from the Backend. If the Target is not a name but an IP address, a name is created on the fly.

func NS 

func NS(b ServiceBackend, zone string, state request.Request, opt Options) (records, extra []dns.RR, err error)

NS returns NS records from the backend

func NextOrFailure 

func NextOrFailure(name string, next Handler, ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

NextOrFailure calls next.ServeDNS when next is not nil, otherwise it will return, a ServerFailure and a nil error.

func PTR 

func PTR(b ServiceBackend, zone string, state request.Request, opt Options) (records []dns.RR, err error)

PTR returns the PTR records from the backend, only services that have a domain name as host are included.

func SOA 

func SOA(b ServiceBackend, zone string, state request.Request, opt Options) ([]dns.RR, error)

SOA returns a SOA record from the backend.

func SRV 

func SRV(b ServiceBackend, zone string, state request.Request, opt Options) (records, extra []dns.RR, err error)

SRV returns SRV records from the Backend. If the Target is not a name but an IP address, a name is created on the fly.

func SplitHostPort 

func SplitHostPort(s string) (host, port string, ipnet *net.IPNet, err error)

SplitHostPort splits s up in a host and port portion, taking reverse address notation into account. String the string s should *not* be prefixed with any protocols, i.e. dns://. The returned ipnet is the *net.IPNet that is used when the zone is a reverse and a netmask is given.

func TXT 

func TXT(b ServiceBackend, zone string, state request.Request, opt Options) (records []dns.RR, err error)

TXT returns TXT records from Backend or an error.

Types

type Handler 

type Handler interface {
	ServeDNS(context.Context, dns.ResponseWriter, *dns.Msg) (int, error)
	Name() string
}

Handler is like dns.Handler except ServeDNS may return an rcode and/or error.

If ServeDNS writes to the response body, it should return a status code. If the status code is not one of the following:

* SERVFAIL (dns.RcodeServerFailure)

* REFUSED (dns.RecodeRefused)

* FORMERR (dns.RcodeFormatError)

* NOTIMP (dns.RcodeNotImplemented)

CoreDNS assumes *no* reply has yet been written. All other response codes signal other handlers above it that the response message is already written, and that they should not write to it also.

If ServeDNS encounters an error, it should return the error value so it can be logged by designated error-handling plugin.

If writing a response after calling another ServeDNS method, the returned rcode SHOULD be used when writing the response.

If handling errors after calling another ServeDNS method, the returned error value SHOULD be logged or handled accordingly.

Otherwise, return values should be propagated down the plugin chain by returning them unchanged.

type HandlerFunc 

type HandlerFunc func(context.Context, dns.ResponseWriter, *dns.Msg) (int, error)

HandlerFunc is a convenience type like dns.HandlerFunc, except ServeDNS returns an rcode and an error. See Handler documentation for more information.

func (HandlerFunc) Name 

func (f HandlerFunc) Name() string

Name implements the Handler interface.

func (HandlerFunc) ServeDNS 

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

ServeDNS implements the Handler interface.

type Host 

type Host string

Host represents a host from the Corefile, may contain port.

func (Host) Normalize 

func (h Host) Normalize() string

Normalize will return the host portion of host, stripping of any port or transport. The host will also be fully qualified and lowercased.

type Name 

type Name string

Name represents a domain name.

func (Name) Matches 

func (n Name) Matches(child string) bool

Matches checks to see if other is a subdomain (or the same domain) of n. This method assures that names can be easily and consistently matched.

func (Name) Normalize 

func (n Name) Normalize() string

Normalize lowercases and makes n fully qualified.

type Options 

type Options struct{}

Options are extra options that can be specified for a lookup.

type Plugin 

type Plugin func(Handler) Handler

Plugin is a middle layer which represents the traditional idea of plugin: it chains one Handler to the next by being passed the next Handler in the chain.

type ServerCtx 

type ServerCtx struct{}

ServerCtx is the context key to pass server address context to the plugins handling the request.

type ServiceBackend 

type ServiceBackend interface {
	// Services communicates with the backend to retrieve the service definitions. Exact indicates
	// on exact match should be returned.
	Services(state request.Request, exact bool, opt Options) ([]msg.Service, error)

	// Reverse communicates with the backend to retrieve service definition based on a IP address
	// instead of a name. I.e. a reverse DNS lookup.
	Reverse(state request.Request, exact bool, opt Options) ([]msg.Service, error)

	// Lookup is used to find records else where.
	Lookup(state request.Request, name string, typ uint16) (*dns.Msg, error)

	// Returns _all_ services that matches a certain name.
	// Note: it does not implement a specific service.
	Records(state request.Request, exact bool) ([]msg.Service, error)

	// IsNameError return true if err indicated a record not found condition
	IsNameError(err error) bool

	Transferer
}

ServiceBackend defines a (dynamic) backend that returns a slice of service definitions.

type Transferer 

type Transferer interface {
	// Serial returns a SOA serial number to construct a SOA record.
	Serial(state request.Request) uint32

	// MinTTL returns the minimum TTL to be used in the SOA record.
	MinTTL(state request.Request) uint32

	// Transfer handles a zone transfer it writes to the client just
	// like any other handler.
	Transfer(ctx context.Context, state request.Request) (int, error)
}

Transferer defines an interface for backends that provide AXFR of all records.

type Zones 

type Zones []string

Zones respresents a lists of zone names.

func (Zones) Matches 

func (z Zones) Matches(qname string) string

Matches checks if qname is a subdomain of any of the zones in z. The match will return the most specific zones that matches. The empty string signals a not found condition.

func (Zones) Normalize 

func (z Zones) Normalize()

Normalize fully qualifies all zones in z. The zones in Z must be domain names, without a port or protocol prefix.

Source Files

View all Source files

Directories

Path Synopsis
Package auto implements an on-the-fly loading file backend.
 Package auto implements an on-the-fly loading file backend.
Package autopath implements autopathing.
 Package autopath implements autopathing.
Package bind allows binding to a specific interface instead of bind to all of them.
 Package bind allows binding to a specific interface instead of bind to all of them.
Package cache implements a cache.
 Package cache implements a cache.
freq
Package freq keeps track of last X seen events.
 Package freq keeps track of last X seen events.
Package chaos implements a plugin that answer to 'CH version.bind TXT' type queries.
 Package chaos implements a plugin that answer to 'CH version.bind TXT' type queries.
Package deprecated is used when we deprecated plugin.
 Package deprecated is used when we deprecated plugin.
Package dnssec implements a plugin that signs responses on-the-fly using NSEC black lies.
 Package dnssec implements a plugin that signs responses on-the-fly using NSEC black lies.
dnstapio
msg
taprw
Package taprw takes a query and intercepts the response.
 Package taprw takes a query and intercepts the response.
test
Package erratic implements a plugin that returns erratic answers (delayed, dropped).
 Package erratic implements a plugin that returns erratic answers (delayed, dropped).
Package errors implements an error handling plugin.
 Package errors implements an error handling plugin.
Package etcd provides the etcd version 3 backend plugin.
 Package etcd provides the etcd version 3 backend plugin.
msg
Package msg defines the Service structure which is used for service discovery.
 Package msg defines the Service structure which is used for service discovery.
Package federation implements kubernetes federation.
 Package federation implements kubernetes federation.
Package file implements a file backend.
 Package file implements a file backend.
tree
Package tree implements Left-Leaning Red Black trees as described by Robert Sedgewick.
 Package tree implements Left-Leaning Red Black trees as described by Robert Sedgewick.
Package forward implements a forwarding proxy.
 Package forward implements a forwarding proxy.
Package health implements an HTTP handler that responds to health checks.
 Package health implements an HTTP handler that responds to health checks.
Package external implements external names for kubernetes clusters.
 Package external implements external names for kubernetes clusters.
Package kubernetes provides the kubernetes backend.
 Package kubernetes provides the kubernetes backend.
object
Package object holds functions that convert the objects from the k8s API in to a more memory efficient structures.
 Package object holds functions that convert the objects from the k8s API in to a more memory efficient structures.
Package loadbalance is plugin for rewriting responses to do "load balancing" Package loadbalance shuffles A, AAAA and MX records.
 Package loadbalance is plugin for rewriting responses to do "load balancing" Package loadbalance shuffles A, AAAA and MX records.
Package log implements basic but useful request (access) logging plugin.
 Package log implements basic but useful request (access) logging plugin.
Package metadata provides an API that allows plugins to add metadata to the context.
 Package metadata provides an API that allows plugins to add metadata to the context.
Package metrics implement a handler and plugin that provides Prometheus metrics.
 Package metrics implement a handler and plugin that provides Prometheus metrics.
vars
Package nsid implements NSID protocol
 Package nsid implements NSID protocol
pkg
cache
Package cache implements a cache.
 Package cache implements a cache.
dnstest
Package dnstest allows for easy testing of DNS client against a test server.
 Package dnstest allows for easy testing of DNS client against a test server.
dnsutil
Package dnsutil contains DNS related helper functions.
 Package dnsutil contains DNS related helper functions.
doh
edns
Package edns provides function useful for adding/inspecting OPT records to/in messages.
 Package edns provides function useful for adding/inspecting OPT records to/in messages.
fall
Package fall handles the fallthrough logic used in plugins that support it.
 Package fall handles the fallthrough logic used in plugins that support it.
fuzz
Package fuzz contains functions that enable fuzzing of plugins.
 Package fuzz contains functions that enable fuzzing of plugins.
healthcheck
log
Package log implements a small wrapper around the std lib log package.
 Package log implements a small wrapper around the std lib log package.
nonwriter
Package nonwriter implements a dns.ResponseWriter that never writes, but captures the dns.Msg being written.
 Package nonwriter implements a dns.ResponseWriter that never writes, but captures the dns.Msg being written.
parse
Package parse contains functions that can be used in the setup code for plugins.
 Package parse contains functions that can be used in the setup code for plugins.
rcode
replacer
response
singleflight
Package singleflight provides a duplicate function call suppression mechanism.
 Package singleflight provides a duplicate function call suppression mechanism.
tls
trace
transport
uniq
Package uniq keeps track of "thing" that are either "todo" or "done".
 Package uniq keeps track of "thing" that are either "todo" or "done".
up
Package up is used to run a function for some duration.
 Package up is used to run a function for some duration.
upstream
Package upstream abstracts a upstream lookups so that plugins can handle them in an unified way.
 Package upstream abstracts a upstream lookups so that plugins can handle them in an unified way.
Package pprof implement a debug endpoint for getting profiles using the go pprof tooling.
 Package pprof implement a debug endpoint for getting profiles using the go pprof tooling.
Package proxy is plugin that proxies requests.
 Package proxy is plugin that proxies requests.
Package rewrite is plugin for rewriting requests internally to something different.
 Package rewrite is plugin for rewriting requests internally to something different.
Package route53 implements a plugin that returns resource records from AWS route53.
 Package route53 implements a plugin that returns resource records from AWS route53.
Package secondary implements a secondary plugin.
 Package secondary implements a secondary plugin.
Package test contains helper functions for writing plugin tests.
 Package test contains helper functions for writing plugin tests.
Package trace implements OpenTracing-based tracing
 Package trace implements OpenTracing-based tracing
Package whoami implements a plugin that returns details about the resolving querying it.
 Package whoami implements a plugin that returns details about the resolving querying it.

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