lightdns

README

lightdns

This is a light weight DNS Server which serves A type record for now.

Installation

go get github.com/openmohan/lightdns

Requirements

• Go 1.90

Usage

1. Import the package lightdns "github.com/openmohan/lightdns"
2. Create a DNS Server dns := lightdns.NewDNSServer(port_int)
3. Add Zone data using the function AddZoneData

dns.AddZoneData(zone, staticRecords, lookupFunction, ZoneType)

Example

If the records data available we can code it and Add the zone data

	var googleRecords = map[string]string{
		"mail.google.com":  "192.168.0.2",
		"paste.google.com": "192.168.0.3",
	}
	dns.AddZoneData("google.com", googleRecords, nil, lightdns.DNSForwardLookupZone)

or

If the data is not static and has to be taken from a DB or from any other sources or calculated dynamically then use lookup function. Define a lookup function in the format

func lookupFunc(domain string) (ip string, err error) ie: given a domain name string as parameter, IP string and error value has to be returned.

	func lookupFunc(string) (string, error) {
		//Do some action
		//Get data from DB
		//Process it further more
		return "192.2.2.1", nil
	}
	dns.AddZoneData("amazon.com", nil, lookupFunc, lightdns.DNSForwardLookupZone)

1. Start the DNS Server by dns.StartAndServe()

Complete Example

package main

import (
	lightdns "github.com/openmohan/lightdns"
)

var records = map[string]string{
	"mail.amazon.com":  "192.162.1.2",
	"paste.amazon.com": "191.165.0.3",
}

func lookupFunc(string) (string, error) {
	//Do some action
	//Get data from DB
	//Process it further more
	return "192.2.2.1", nil
}

func main() {
	var googleRecords = map[string]string{
		"mail.google.com":  "192.168.0.2",
		"paste.google.com": "192.168.0.3",
	}
	var microsoftRecords = map[string]string{
		"mail.microsoft.com":  "192.168.0.78",
		"paste.microsoft.com": "192.168.0.25",
	}
	dns := lightdns.NewDNSServer(1234)
	dns.AddZoneData("google.com", googleRecords, nil, lightdns.DNSForwardLookupZone)
	dns.AddZoneData("microsoft.com", microsoftRecords, nil, lightdns.DNSForwardLookupZone)

	/* Incase if the records are not static or to be taken from DB or from any other sources
	lookupFunc method can be used.append*/
	dns.AddZoneData("amazon.com", nil, lookupFunc, lightdns.DNSForwardLookupZone)
	dns.StartAndServe()
}

Work in progress

Support for

1. MX, AAAA, SOA and other records
2. Reverse lookup zone

Code

1. Use goroutines for optimizing the speed
2. Unit Test Cases
3. Logging mechanism for monitoring and debugging
4. Error handling

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

License

MIT

Documentation

Index

• func NewServeMux() *serveMux
• type DNSServer
  • func NewDNSServer(port int) *DNSServer
  • func (dns *DNSServer) AddZoneData(zone string, records map[string]string, ...)
  • func (dns *DNSServer) StartAndServe()
• type Handler
• type ZoneType

Functions

func NewServeMux

func NewServeMux() *serveMux

NewServeMux - creates a servemux with handler field intialised

Types

type DNSServer

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

DNSServer is the contains the runtime information

func NewDNSServer

func NewDNSServer(port int) *DNSServer

NewDNSServer - Creates new DNSServer

func (*DNSServer) AddZoneData

func (dns *DNSServer) AddZoneData(zone string, records map[string]string, lookupFunc func(string) (string, error), lookupZone ZoneType)

AddZoneData - Depending on the zoneType and recordType this function generates appropriate handler and registers in the serveMux

func (*DNSServer) StartAndServe

func (dns *DNSServer) StartAndServe()

StartToServe - creates a UDP connection and uses the connection to serve DNS

type Handler

type Handler interface {
	// contains filtered or unexported methods
}

type ZoneType

type ZoneType uint16

const (
	DNSForwardLookupZone ZoneType = 1
	DNSReverseLookupZone ZoneType = 2 //Todo
)