godns/hosts/hosts.go

package hosts

import (
	"net"
	"time"
)

const (
	notIPQuery = 0
	_IP4Query  = 4
	_IP6Query  = 6
)

var (
	zeroDuration = time.Duration(0)
)

type Hosts interface {
	Get(domain string, family int) ([]net.IP, time.Duration, bool)
}

type ProviderList struct {
	providers       []Provider
}

type Provider interface {
	Get(domain string) ([]string, time.Duration, bool)
}

func NewHosts(providers []Provider) Hosts {
	return &ProviderList{providers}
}

/*
Match local /etc/hosts file first, remote redis records second
*/
func (h *ProviderList) Get(domain string, family int) ([]net.IP, time.Duration, bool) {
	var sips []string
	var ok bool
	var ip net.IP
	var ips []net.IP
	var ttl time.Duration

	for _, provider := range h.providers {
		sips, ttl, ok = provider.Get(domain)

		if ok {
			break
		}
	}

	if sips == nil {
		return nil, zeroDuration, false
	}

	for _, sip := range sips {
		switch family {
		case _IP4Query:
			ip = net.ParseIP(sip).To4()
		case _IP6Query:
			ip = net.ParseIP(sip).To16()
		default:
			continue
		}
		if ip != nil {
			ips = append(ips, ip)
		}
	}

	return ips, ttl, ips != nil
}