dialburn/server/main.go

package main

import (
	"encoding/xml"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	"dialburn/common"

	"github.com/gorilla/mux"
)

type TwiML struct {
	XMLName   xml.Name `xml:"Response"`
	GatherTag Gather   `xml:"Gather"`
	Hangup    string   `xml:"Hangup"`
}

type Gather struct {
	XMLName   xml.Name `xml:"Gather"`
	Action    string   `xml:"action,attr"`
	NumDigits string   `xml:"numDigits,attr"`
	TimeOut   string   `xml:"timeout,attr"`
	Play      string   `xml:"Play"`
}

type Feedback struct {
	XMLName xml.Name `xml:"Response"`
	Play    string   `xml:"Play"`
	Hangup  string   `xml:"Hangup"`
}

var trigger = false

func twiml(w http.ResponseWriter, r *http.Request) {
	g := Gather{Action: common.SERVPATH + "/code", NumDigits: "3", TimeOut: "120", Play: common.MUSIC}
	twiml := TwiML{GatherTag: g}
	x, err := xml.Marshal(twiml)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/xml")
	w.Write(x)
}

func action(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()

	var twiml Feedback
	if r.Form.Get("Digits") == "666" {
		common.Info("received valid code")
		twiml = Feedback{Play: common.ACCEPTED}
		trigger = true
	} else {
		common.Info("received invalid code")
		twiml = Feedback{Play: common.DENIED}
	}
	x, err := xml.Marshal(twiml)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/xml")
	w.Write(x)
}

func enroll(w http.ResponseWriter, r *http.Request) {
	addr := strings.Split(r.RemoteAddr, ":")[0]
	data, _ := os.ReadFile(common.AGENTLOG)
	if strings.Contains(string(data), addr) {
		w.WriteHeader(http.StatusConflict)
	} else {
		fd, _ := os.OpenFile(common.AGENTLOG, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)

		defer fd.Close()
		if _, err := fd.WriteString(addr + "\n"); err != nil {
			common.Warning("error writing to " + common.AGENTLOG + " during enrollment")
		} else {
			common.Success("enrolled " + addr + " at " + time.Now().Format(time.RFC3339))
		}
		w.WriteHeader(http.StatusAccepted)
	}
}

func shutitdown() {
	data, _ := os.ReadFile(common.AGENTLOG)
	var wg sync.WaitGroup
	for _, addr := range strings.Split(string(data), "\n") {
		if addr != "" {
			wg.Add(1)
			go func(addr string) {
				defer wg.Done()
				common.Info("sending burn request to " + addr)
				_, err := http.Get("http://" + addr + ":" + common.AGENTLPORT + common.AGENTPATH)
				if err != nil {
					common.Warning("error sending burn request to " + addr)
				}
			}(addr)
		}
	}
	wg.Wait()
}

func main() {
	common.Banner()
	if _, err := os.Stat(common.AGENTLOG); os.IsNotExist(err) {
		fd, err := os.Create(common.AGENTLOG)
		if err != nil {
			common.Fatal("failed to create " + common.AGENTLOG)
		} else {
			common.Success("created " + common.AGENTLOG)
			fd.Close()
		}
	}

	go func() {
		for {
			if trigger {
				shutitdown()
				trigger = false
			}
			time.Sleep(500 * time.Millisecond)
		}
	}()

	r := mux.NewRouter()
	r.HandleFunc(common.SERVPATH, twiml).Methods("POST")
	r.HandleFunc(common.SERVPATH+"/code", action).Methods("POST")
	r.HandleFunc(common.SERVPATH+"/enroll", enroll).Methods("PUT")
	http.Handle("/", r)

	serv := &http.Server{
		Addr:        ":" + common.SERVLPORT,
		Handler:     r,
		ErrorLog:    nil,
		IdleTimeout: 10 * time.Second,
	}

	common.Warning("dont get caught in the first place!")
	common.Info("starting dialburn server port " + common.SERVLPORT)
	if err := serv.ListenAndServe(); err != nil {
		common.Fatal("failed to start listener on port " + common.SERVLPORT)
	}

}