First commit

.env.example

@@ -0,0 +1,6 @@
+ALLOWED_DOMAINS=xyz.com,abc.de,fgh.il
+CAPTCHA_SERVER_KEY=
+OL_INSTANCE=
+OL_ADMIN_EMAIL=
+OL_ADMIN_PASSWORD=
+PORT=3000

.gitignore

@@ -0,0 +1 @@
+.env

Dockerfile

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+FROM golang:1.20-alpine
+
+WORKDIR /app
+
+COPY . .
+
+RUN go mod tidy
+RUN go build -o app .
+
+CMD ["./app"]

captcha.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+type CaptchaResponse struct {
+	Success bool `json:"success"`
+}
+
+func ValidateCaptcha(captcha string) bool {
+	secretKey := os.Getenv("CAPTCHA_SERVER_KEY")
+	if secretKey == "" {
+		return true // Skip validation if CAPTCHA is disabled
+	}
+
+	resp, err := http.PostForm("https://www.google.com/recaptcha/api/siteverify", url.Values{
+		"secret":   {secretKey},
+		"response": {captcha},
+	})
+	if err != nil {
+		return false
+	}
+	defer resp.Body.Close()
+
+	var result CaptchaResponse
+	err = json.NewDecoder(resp.Body).Decode(&result)
+	return err == nil && result.Success
+}

handlers.go

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+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"os"
+	"strings"
+)
+
+type RegisterRequest struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	Captcha  string `json:"captcha"`
+}
+
+func RegisterHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	// Parse the request
+	var req RegisterRequest
+	err := json.NewDecoder(r.Body).Decode(&req)
+	if err != nil {
+		http.Error(w, "Invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	// Validate email domain
+	allowedDomains := strings.Split(os.Getenv("ALLOWED_DOMAINS"), ",")
+	if !isDomainAllowed(req.Email, allowedDomains) {
+		http.Error(w, "Email domain not allowed", http.StatusForbidden)
+		return
+	}
+
+	// Validate CAPTCHA
+	if !ValidateCaptcha(req.Captcha) {
+		http.Error(w, "Invalid CAPTCHA", http.StatusUnauthorized)
+		return
+	}
+
+	// Register user
+	overleaf := NewOverleaf(os.Getenv("OL_INSTANCE"))
+	err = overleaf.Login(os.Getenv("OL_ADMIN_EMAIL"), os.Getenv("OL_ADMIN_PASSWORD"))
+	if err != nil {
+		http.Error(w, "Failed to log in as admin", http.StatusInternalServerError)
+		return
+	}
+
+	err = overleaf.RegisterUser(req.Email, req.Password)
+	if err != nil {
+		http.Error(w, "Failed to register user: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusCreated)
+	json.NewEncoder(w).Encode(map[string]string{"message": "User registered successfully"})
+}
+
+func isDomainAllowed(email string, allowedDomains []string) bool {
+	parts := strings.Split(email, "@")
+	if len(parts) != 2 {
+		return false
+	}
+	domain := parts[1]
+	for _, allowed := range allowedDomains {
+		if domain == allowed {
+			return true
+		}
+	}
+	return false
+}

main.go

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+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/joho/godotenv"
+)
+
+func main() {
+	// Load environment variables
+	err := godotenv.Load()
+	if err != nil {
+		log.Println("No .env file found, using environment variables")
+	}
+
+	// Register the HTTP handler
+	http.HandleFunc("/register", RegisterHandler)
+
+	// Start the HTTP server
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "3000"
+	}
+	log.Printf("Server running on port %s\n", port)
+	log.Fatal(http.ListenAndServe(":"+port, nil))
+}

overleaf.go

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+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+type Overleaf struct {
+	BaseURL string
+	Client  *http.Client
+	CSRF    string
+}
+
+// NewOverleaf initializes a new Overleaf instance
+func NewOverleaf(baseURL string) *Overleaf {
+	return &Overleaf{
+		BaseURL: strings.TrimSuffix(baseURL, "/"),
+		Client:  &http.Client{},
+	}
+}
+
+// get performs a GET request
+func (o *Overleaf) get(endpoint string) (*http.Response, error) {
+	url := fmt.Sprintf("%s%s", o.BaseURL, endpoint)
+	return o.Client.Get(url)
+}
+
+// post performs a POST request
+func (o *Overleaf) post(endpoint string, data map[string]string) (*http.Response, error) {
+	if o.CSRF == "" {
+		if err := o.obtainCSRF(); err != nil {
+			return nil, err
+		}
+	}
+
+	url := fmt.Sprintf("%s%s", o.BaseURL, endpoint)
+	data["_csrf"] = o.CSRF
+	formData := encodeFormData(data)
+
+	req, err := http.NewRequest("POST", url, bytes.NewBufferString(formData))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	return o.Client.Do(req)
+}
+
+// obtainCSRF retrieves the CSRF token
+func (o *Overleaf) obtainCSRF() error {
+	resp, err := o.get("/login")
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	doc, err := goquery.NewDocumentFromReader(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	csrf, exists := doc.Find(`meta[name="ol-csrfToken"]`).Attr("content")
+	if !exists {
+		return errors.New("CSRF token not found")
+	}
+	o.CSRF = csrf
+	return nil
+}
+
+// Login as admin
+func (o *Overleaf) Login(email, password string) error {
+	resp, err := o.post("/login", map[string]string{
+		"email":    email,
+		"password": password,
+	})
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return errors.New("failed to log in as admin")
+	}
+	return nil
+}
+
+// RegisterUser registers a new user
+func (o *Overleaf) RegisterUser(email, password string) error {
+	resp, err := o.post("/admin/register", map[string]string{
+		"email":    email,
+		"password": password,
+	})
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("failed to register user: %s", string(body))
+	}
+	return nil
+}
+
+// encodeFormData encodes a map into x-www-form-urlencoded format
+func encodeFormData(data map[string]string) string {
+	var formData []string
+	for key, value := range data {
+		formData = append(formData, fmt.Sprintf("%s=%s", key, value))
+	}
+	return strings.Join(formData, "&")
+}