createAuthChallenge.go

package main

import (
	"context"
	"errors"
	"fmt"
	"log"
	"math/rand"
	"time"

	"github.com/aws/aws-lambda-go/lambda"
)

func main() {
	lambda.Start(createAuthChallenge)
}

type Req map[string]interface{}

func createAuthChallenge(ctx context.Context, req Req) (interface{}, error) {
	fmt.Println("called create auth challenge")

	for k, v := range req {
		log.Println(fmt.Sprintf("%s => %v", k, v))
	}

	reqReq, isErr := req["request"].(map[string]interface{})
	if !isErr {
		return nil, errors.New("cannot convert request")
	}

	response, isErr := req["response"].(map[string]interface{})
	if !isErr {
		return nil, errors.New("cannot convert response")
	}

	if reqReq["challengeName"].(string) == "CUSTOM_CHALLENGE" {
		challengeAnswer := createChallengeString()
		if err := sendChallengeString(challengeAnswer); err != nil {
			return req, err
		}
		response["publicChallengeParameters"] = map[string]string{"challenge": "チャレンジです"}
		response["privateChallengeParameters"] = map[string]string{"answer": challengeAnswer}
		response["challengeMetadata"] = "SECRET_CHALLENGE"
	}
	log.Println(fmt.Sprintf("response: %v", response))

	req["response"] = response
	return req, nil
}

func createChallengeString() string {
	rand.Seed(time.Now().UnixNano())
	return fmt.Sprintf("%d", rand.Intn(9999))
}

func sendChallengeString(challengeAnswer string) error {
	log.Println(fmt.Sprintf("challenge answer: %s", challengeAnswer))
	// TODO: send email...
	return nil
}