package main

    import (
        "bufio"
        "fmt"
        "log"
        "github.com/globalsign/mgo"
        "github.com/globalsign/mgo/bson"
        "net/url"
        "os"
        "strings"
    )

    /*
     *
     * PowerDNS Pipe Backend
     * For H6G DNS - connecting to MongoDB
     *

     * Recordtypes:
     * A - 1
     * NS - 2
     * CNAME - 5
     * SOA - 6
     * MX - 15
     * TXT - 16
     * AAAA - 28
     * SRV - 33
     * NAPTR - 35
     * CAA - 257
     */

    type dnsrecord struct {
        ID    bson.ObjectId `bson:"_id,omitempty"`
        Qtype uint          `bson:"type"`
        TTL   uint          `bson:"TTL"`
        Name  string
        Value string
        SOA_p *SOArecord    `bson:"SOA"`
        Zone  bson.ObjectId `bson:"zone,omitempty"`
    }

    type SOArecord struct {
        Primary string        `bson:"primary"`
        Mail    string        `bson:"mail"`
        Serial  bson.ObjectId `bson:"serial,omitempty"`
        Refresh uint          `bson:"refresh"`
        Retry   uint          `bson:"retry"`
        Expire  uint          `bson:"expire"`
        TTL     uint          `bson:"TTL"`
    }

    func main() {
        l := log.New(os.Stderr, "", 0)

        if len(os.Args) < 2 {
            l.Printf("Call: %s [DB-Pass]\n", os.Args[0])
            return
        }

        var input string
        stdin := bufio.NewReader(os.Stdin)
        input, _ = stdin.ReadString('\n')

        //Handshake ABI Version 1
        for input != "HELO\t1\n" {
            fmt.Printf("FAIL\n")
            l.Println("Received: ", input)
            input, _ = stdin.ReadString('\n')
        }

        dbsession, err := mgo.Dial(fmt.Sprintf("dns:%s@/var/run/mongodb/mongodb-27017.sock/h6g_dns", url.QueryEscape(os.Args[1])))
        if err != nil {
            fmt.Printf("FAIL\n")
            l.Println("H6GDNS DB: ", err.Error())
            return
        }
        db := dbsession.DB("h6g_dns")

        fmt.Printf("OK\tH6G DNS Connector\n")

    loop:
        for {
            var qtype uint
            var response_p []dnsrecord
            var needle bson.M
            input, _ = stdin.ReadString('\n')
            q := strings.Split(input, "\t")

            if len(q) < 4 {
                fmt.Println("FAIL")
                l.Println("H6GDNS: Input too short")
                continue
            }

            switch q[3] {
            case "ANY":
                qtype = 0
            case "A":
                qtype = 1
            case "NS":
                qtype = 2
            case "CNAME":
                qtype = 5
            case "SOA":
                qtype = 6
            case "MX":
                qtype = 15
            case "TXT":
                qtype = 16
            case "AAAA":
                qtype = 28
            case "SRV":
                qtype = 33
            case "NAPTR":
                qtype = 35
            case "CAA":
                qtype = 257
            default:
                fmt.Println("FAIL")
                l.Println("H6GDNS: unknown qtype")
                continue loop
            }

            if qtype == 0 {
                //ANY Record
                needle = bson.M{"name": q[1]}
            } else {
                needle = bson.M{"name": q[1], "type": qtype}
            }

            query := db.C("dns").Find(needle)

            if n, _ := query.Count(); n > 0 {
                var qtypetxt string
                err = query.All(&response_p)
                if err != nil {
                    fmt.Println("FAIL")
                    break
                }

            responseloop:
                for _, response := range response_p {

                    switch response.Qtype {
                    case 1:
                        qtypetxt = "A"
                    case 2:
                        qtypetxt = "NS"
                    case 5:
                        qtypetxt = "CNAME"
                    case 6:
                        qtypetxt = "SOA"
                        fmt.Printf("DATA\t%s\tIN\t%s\t%d\t-1\t%s %s %d %d %d %d %d\n",
                            response.Name, qtypetxt, response.TTL, response.SOA_p.Primary,
                            response.SOA_p.Mail, response.SOA_p.Serial.Time().Unix(), response.SOA_p.Refresh,
                            response.SOA_p.Retry, response.SOA_p.Expire, response.SOA_p.TTL)
                        continue responseloop
                    case 15:
                        qtypetxt = "MX"
                    case 16:
                        qtypetxt = "TXT"
                    case 28:
                        qtypetxt = "AAAA"
                    case 33:
                        qtypetxt = "SRV"
                    case 35:
                        qtypetxt = "NAPTR"
                    case 257:
                        qtypetxt = "CAA"
                    }

                    fmt.Printf("DATA\t%s\tIN\t%s\t%d\t-1\t%s\n", response.Name, qtypetxt, response.TTL, response.Value)
                }
            }

            fmt.Println("END")

        }

    }