Cloudflare CAPTCHA for account signup page

pkg/config/variable.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 
 	"code.nonshy.com/nonshy/website/pkg/encryption/keygen"
@@ -14,7 +13,7 @@ import (
 
 // Version of the config format - when new fields are added, it will attempt
 // to write the settings.toml to disk so new defaults populate.
-var currentVersion = 2
+var currentVersion = 3
 
 // Current loaded settings.json
 var Current = DefaultVariable()
@@ -31,6 +30,7 @@ type Variable struct {
 	BareRTC          BareRTC
 	Maintenance      Maintenance
 	Encryption       Encryption
+	Turnstile        Turnstile
 	UseXForwardedFor bool
 }
 
@@ -62,7 +62,7 @@ func LoadSettings() {
 
 	if _, err := os.Stat(SettingsPath); !os.IsNotExist(err) {
 		log.Info("Loading settings from %s", SettingsPath)
-		content, err := ioutil.ReadFile(SettingsPath)
+		content, err := os.ReadFile(SettingsPath)
 		if err != nil {
 			panic(fmt.Sprintf("LoadSettings: couldn't read settings.json: %s", err))
 		}
@@ -119,7 +119,7 @@ func WriteSettings() error {
 		panic(fmt.Sprintf("WriteSettings: couldn't marshal settings: %s", err))
 	}
 
-	return ioutil.WriteFile(SettingsPath, buf.Bytes(), 0600)
+	return os.WriteFile(SettingsPath, buf.Bytes(), 0600)
 }
 
 // Mail settings.
@@ -165,3 +165,10 @@ type Maintenance struct {
 type Encryption struct {
 	AESKey []byte
 }
+
+// Turnstile (Cloudflare CAPTCHA) settings.
+type Turnstile struct {
+	Enabled   bool
+	SiteKey   string
+	SecretKey string
+}

pkg/controller/account/signup.go

@@ -14,6 +14,7 @@ import (
 	"code.nonshy.com/nonshy/website/pkg/models"
 	"code.nonshy.com/nonshy/website/pkg/redis"
 	"code.nonshy.com/nonshy/website/pkg/session"
+	"code.nonshy.com/nonshy/website/pkg/spam"
 	"code.nonshy.com/nonshy/website/pkg/templates"
 	"code.nonshy.com/nonshy/website/pkg/utility"
 	"github.com/google/uuid"
@@ -71,7 +72,6 @@ func Signup() http.HandlerFunc {
 			vars["SignupToken"] = tokenStr
 			vars["Email"] = token.Email
 		}
-		log.Info("Vars: %+v", vars)
 
 		// Posting?
 		if r.Method == http.MethodPost {
@@ -86,10 +86,33 @@ func Signup() http.HandlerFunc {
 				password2 = strings.TrimSpace(r.PostFormValue("password2"))
 				dob       = r.PostFormValue("dob")
 
+				// CAPTCHA response.
+				turnstileCAPTCHA = r.PostFormValue("cf-turnstile-response")
+
+				// Honeytrap fields for lazy spam bots.
+				honeytrap1 = r.PostFormValue("phone") == ""
+				honeytrap2 = r.PostFormValue("referral") == "Word of mouth"
+
 				// Validation errors but still show the form again.
 				hasError bool
 			)
 
+			// Honeytrap fields check.
+			if !honeytrap1 || !honeytrap2 {
+				session.Flash(w, r, "We have sent an e-mail to %s with a link to continue signing up your account. Please go and check your e-mail.", email)
+				templates.Redirect(w, r.URL.Path)
+				return
+			}
+
+			// Validate the CAPTCHA token.
+			if config.Current.Turnstile.Enabled {
+				if err := spam.ValidateTurnstileCAPTCHA(turnstileCAPTCHA, "signup"); err != nil {
+					session.FlashError(w, r, "There was an error validating your CAPTCHA response.")
+					templates.Redirect(w, r.URL.Path)
+					return
+				}
+			}
+
 			// Don't let them sneakily change their verified email address on us.
 			if vars["SignupToken"] != "" && email != vars["Email"] {
 				session.FlashError(w, r, "This email address is not verified. Please start over from the beginning.")
@@ -119,17 +142,21 @@ func Signup() http.HandlerFunc {
 			if _, err := models.FindUser(email); err == nil {
 				// We don't want to admit that the email already is registered, so send an email to the
 				// address in case the user legitimately forgot, but flash the regular success message.
-				err := mail.Send(mail.Message{
-					To:       email,
-					Subject:  "You already have a nonshy account",
-					Template: "email/already_signed_up.html",
-					Data: map[string]interface{}{
-						"Title": config.Title,
-						"URL":   config.Current.BaseURL + "/forgot-password",
-					},
-				})
-				if err != nil {
-					session.FlashError(w, r, "Error sending an email: %s", err)
+				if err := mail.LockSending("signup", email, config.SignupTokenExpires); err == nil {
+					err := mail.Send(mail.Message{
+						To:       email,
+						Subject:  "You already have a nonshy account",
+						Template: "email/already_signed_up.html",
+						Data: map[string]interface{}{
+							"Title": config.Title,
+							"URL":   config.Current.BaseURL + "/forgot-password",
+						},
+					})
+					if err != nil {
+						session.FlashError(w, r, "Error sending an email: %s", err)
+					}
+				} else {
+					log.Error("LockSending: signup e-mail is not sent to %s: one was sent recently", email)
 				}
 
 				session.Flash(w, r, "We have sent an e-mail to %s with a link to continue signing up your account. Please go and check your e-mail.", email)
@@ -158,17 +185,21 @@ func Signup() http.HandlerFunc {
 					return
 				}
 
-				err := mail.Send(mail.Message{
-					To:       email,
-					Subject:  "Verify your e-mail address",
-					Template: "email/verify_email.html",
-					Data: map[string]interface{}{
-						"Title": config.Title,
-						"URL":   config.Current.BaseURL + "/signup?token=" + token.Token,
-					},
-				})
-				if err != nil {
-					session.FlashError(w, r, "Error sending an email: %s", err)
+				if err := mail.LockSending("signup", email, config.SignupTokenExpires); err == nil {
+					err := mail.Send(mail.Message{
+						To:       email,
+						Subject:  "Verify your e-mail address",
+						Template: "email/verify_email.html",
+						Data: map[string]interface{}{
+							"Title": config.Title,
+							"URL":   config.Current.BaseURL + "/signup?token=" + token.Token,
+						},
+					})
+					if err != nil {
+						session.FlashError(w, r, "Error sending an email: %s", err)
+					}
+				} else {
+					log.Error("LockSending: signup e-mail is not sent to %s: one was sent recently", email)
 				}
 
 				session.Flash(w, r, "We have sent an e-mail to %s with a link to continue signing up your account. Please go and check your e-mail.", email)

pkg/mail/mail.go

@@ -7,9 +7,12 @@ import (
 	"fmt"
 	"html/template"
 	"strings"
+	"time"
 
 	"code.nonshy.com/nonshy/website/pkg/config"
+	"code.nonshy.com/nonshy/website/pkg/encryption"
 	"code.nonshy.com/nonshy/website/pkg/log"
+	"code.nonshy.com/nonshy/website/pkg/redis"
 	"github.com/microcosm-cc/bluemonday"
 	"gopkg.in/gomail.v2"
 )
@@ -23,6 +26,22 @@ type Message struct {
 	Data     map[string]interface{}
 }
 
+// LockSending emails to the same address within 24 hours, e.g.: on the signup form to reduce chance for spam abuse.
+//
+// Call this before calling Send() if you want to throttle the sending. This function will put a key in Redis on
+// the first call and return nil; on subsequent calls, if the key still remains, it will return an error.
+func LockSending(namespace, email string, expires time.Duration) error {
+	var key = fmt.Sprintf("mail/lock-sending/%s/%s", namespace, encryption.Hash([]byte(email)))
+
+	// See if we have already locked it.
+	if redis.Exists(key) {
+		return errors.New("email was in the lock-sending queue")
+	}
+
+	redis.Set(key, email, expires)
+	return nil
+}
+
 // Send an email.
 func Send(msg Message) error {
 	conf := config.Current.Mail

pkg/spam/captcha.go

@@ -0,0 +1,73 @@
+package spam
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"code.nonshy.com/nonshy/website/pkg/config"
+	"code.nonshy.com/nonshy/website/pkg/log"
+)
+
+// ValidateTurnstileCAPTCHA tests a Cloudflare Turnstile CAPTCHA token.
+func ValidateTurnstileCAPTCHA(token, actionName string) error {
+	if !config.Current.Turnstile.Enabled {
+		return errors.New("Cloudflare Turnstile CAPTCHA is not enabled in the server settings")
+	}
+
+	// Prepare the request.
+	form := url.Values{}
+	form.Add("secret", config.Current.Turnstile.SecretKey)
+	form.Add("response", token)
+	url := "https://challenges.cloudflare.com/turnstile/v0/siteverify"
+	req, err := http.NewRequest("POST", url, strings.NewReader(form.Encode()))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	// Make the request.
+	client := &http.Client{
+		Timeout: 10 * time.Second,
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	// Read the response.
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("Reading response body from Cloudflare: %s", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		log.Error("Turnstile CAPTCHA error (status %d): %s", resp.StatusCode, string(body))
+		return fmt.Errorf("CAPTCHA validation error: status code %d", resp.StatusCode)
+	}
+
+	// Parse the response JSON.
+	type response struct {
+		Success     bool      `json:"success"`
+		ErrorCodes  []string  `json:"error-codes"`
+		ChallengeTS time.Time `json:"challenge_ts"`
+		Hostname    string    `json:"hostname"`
+	}
+	var result response
+	if err := json.Unmarshal(body, &result); err != nil {
+		return fmt.Errorf("parsing result json from Cloudflare: %s", err)
+	}
+
+	if !result.Success {
+		log.Error("Turnstile CAPTCHA error (status %d): %s", resp.StatusCode, string(body))
+		return errors.New("verification failed")
+	}
+
+	return nil
+}

pkg/templates/template_vars.go

@@ -20,6 +20,9 @@ func MergeVars(r *http.Request, m map[string]interface{}) {
 	m["YYYY"] = time.Now().Year()
 	m["WebsiteTheme"] = ""
 
+	// Integrations
+	m["TurnstileCAPTCHA"] = config.Current.Turnstile
+
 	if r == nil {
 		return
 	}

web/static/css/theme.css

@@ -205,3 +205,7 @@ img {
     background-color: #400040;
     height: 64px;
 }
+
+.nonshy-htsignup {
+    display: none;
+}

web/templates/account/signup.html

@@ -166,6 +166,26 @@
             </div>
             {{end}}
 
+            <!-- Honeytrap fields -->
+            <div class="field nonshy-htsignup">
+                <label class="label" for="phone">Phone number:</label>
+                <input type="text" class="input"
+                    placeholder="555-1234"
+                    name="phone"
+                    id="phone">
+                <p class="help">
+                    Please enter a valid phone number for your account.
+                </p>
+            </div>
+            <div class="field nonshy-htsignup">
+                <label class="label" for="referral">How did you hear about us?</label>
+                <input type="text" class="input"
+                    placeholder="Google"
+                    name="referral"
+                    id="referral"
+                    value="Word of mouth">
+            </div>
+
             <div class="field">
                 <label class="checkbox">
                     <input type="checkbox" name="confirm" value="true" required>
@@ -173,6 +193,16 @@
                 </label>
             </div>
 
+            <!-- Cloudflare Turnstile CAPTCHA widget -->
+            {{if .TurnstileCAPTCHA.Enabled}}
+            <div class="field">
+                <div class="cf-turnstile"
+                    data-sitekey="{{.TurnstileCAPTCHA.SiteKey}}"
+                    data-action="signup"
+                ></div>
+            </div>
+            {{end}}
+
             <div class="field">
                 <button type="submit" class="button is-primary">Continue and verify email</button>
             </div>
@@ -181,6 +211,12 @@
 </div>
 {{end}}
 {{define "scripts"}}
+
+<!-- Cloudflare Turnstile CAPTCHA -->
+{{if .TurnstileCAPTCHA.Enabled}}
+<script src="https://challenges.cloudflare.com/turnstile/v0/api.js"></script>
+{{end}}
+
 <script>
 window.addEventListener("DOMContentLoaded", (event) => {
     // Set up username checking script.

web/templates/base.html

@@ -1,6 +1,7 @@
 {{define "title"}}Untitled{{end}}
 {{define "content"}}{{end}}
 {{define "scripts"}}{{end}}
+{{define "head-scripts"}}{{end}}
 {{define "base"}}
 <!DOCTYPE html>
 <html lang="en">
@@ -20,6 +21,7 @@
     <link rel="stylesheet" href="/static/css/theme.css?build={{.BuildHash}}">
     <link rel="manifest" href="/manifest.json">
     <title>{{template "title" .}} - {{ .Title }}</title>
+    {{template "head-scripts" .}}
 </head>
 <body>
     <nav class="navbar" role="navigation" aria-label="main navigation">