dotdb.go

package dns

import (
	"database/sql"
	"time"

	"github.com/u6du/db"
	"github.com/u6du/ex"
)

var Db = db.Db(
	"dns/dot",

	`CREATE TABLE "dot" (
"id"	INTEGER PRIMARY KEY AUTOINCREMENT,
"host"	TEXT NOT NULL UNIQUE,
"delay"	INTEGER NOT NULL DEFAULT 0);
CREATE INDEX "dot.delay" ON "dot" ("delay" ASC);`,

	"INSERT INTO dot(host) values (?)",

	"dns.rubyfish.cn",
	"dot-jp.blahdns.com",
	"dns.google",
	"security-filter-dns.cleanbrowsing.org",
	"dot.securedns.eu",
	"sdns.233py.com",
	"ndns.233py.com",
	"dns.quad9.net",
	"wdns.233py.com",
	"dot-de.blahdns.com",
	"1dot1dot1dot1.cloudflare-dns.com",
	"dns.brahma.world",
)

func DotTxt(name string, verify func(string) bool) (txt *string) {

	Db.With(func(db *sql.DB) {

		c, err := db.Query("select id,host from dot order by delay asc")
		ex.Panic(err)
		var id uint
		var nameserver string
		var costIdLi [][2]uint

		defer func() {
			for _, costId := range costIdLi {
				_, err = db.Exec("UPDATE dot SET delay=? WHERE id=?", costId[0], costId[1])
				ex.Warn(err)
			}
		}()

		for c.Next() {
			ex.Warn(c.Scan(&id, &nameserver))

			start := time.Now()

			txt = DotLookupTxt(name, nameserver, 2)

			cost := uint(time.Since(start).Nanoseconds() / 1000000)

			var verified bool

			if txt == nil {
				cost += 20000
				verified = false
			} else {
				verified = verify(*txt)
				if !verified {
					cost += 10000
				}
			}
			costIdLi = append(costIdLi, [2]uint{cost, id})

			if verified {
				ex.Close(c)
				return
			}
		}
	})
	return txt
}