overleaf-registration-be/handlers.go

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
)

// RegistrationRequest represents the incoming registration request.
type RegistrationRequest struct {
	Email   string `json:"email"`
	Captcha string `json:"captcha"`
}

func registerHandler(w http.ResponseWriter, r *http.Request) {
	// Parse the request body
	var req RegistrationRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, fmt.Sprintf("Invalid request body: %v", err), http.StatusBadRequest)
		return
	}

	log.Printf("Received email: %s", req.Email)
	log.Printf("Received CAPTCHA token: %s", req.Captcha)

	// Validate email domain
	if !validateEmailDomain(req.Email) {
		http.Error(w, "Email domain is not allowed", http.StatusBadRequest)
		return
	}

	// Validate Turnstile token
	valid, err := validateRecaptcha(req.Captcha)
	if err != nil {
		log.Printf("CAPTCHA validation failed: %v", err)
		http.Error(w, fmt.Sprintf("CAPTCHA validation failed: %v", err), http.StatusInternalServerError)
		return
	}
	if !valid {
		log.Println("Invalid CAPTCHA token.")
		http.Error(w, "Invalid CAPTCHA", http.StatusUnauthorized)
		return
	}

	// Continue with Overleaf registration (omitted for brevity)
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(map[string]string{
		"message": "User registered successfully. Please check your email to set your password.",
	})
}

func validateEmailDomain(email string) bool {
	allowedDomains := os.Getenv("ALLOWED_DOMAINS")
	if allowedDomains == "" {
		return false
	}

	parts := strings.Split(email, "@")
	if len(parts) != 2 {
		return false // Invalid email format
	}

	domain := parts[1]
	allowed := strings.Split(allowedDomains, ",")
	for _, allowedDomain := range allowed {
		if strings.TrimSpace(domain) == strings.TrimSpace(allowedDomain) {
			return true
		}
	}
	return false
}

func validateEnvVars(vars []string) error {
	for _, v := range vars {
		if os.Getenv(v) == "" {
			return fmt.Errorf("environment variable %s is not set", v)
		}
	}
	return nil
}