dchest · muharihar · Dec 17, 2020
diff --git a/capexample/redisexample/main.go b/capexample/redisexample/main.go
@@ -0,0 +1,113 @@
+package main
+
+import (
+	"fmt"
+	"html/template"
+	"io"
+	"log"
+	"net/http"
+
+	"github.com/dchest/captcha"
+	"github.com/go-redis/redis"
+)
+
+var formTemplate = template.Must(template.New("example").Parse(formTemplateSrc))
+
+func showFormHandler(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/" {
+		http.NotFound(w, r)
+		return
+	}
+	d := struct {
+		CaptchaId string
+	}{
+		captcha.New(),
+	}
+	if err := formTemplate.Execute(w, &d); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+}
+
+func processFormHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if !captcha.VerifyString(r.FormValue("captchaId"), r.FormValue("captchaSolution")) {
+		io.WriteString(w, "Wrong captcha solution! No robots allowed!\n")
+	} else {
+		io.WriteString(w, "Great job, human! You solved the captcha.\n")
+	}
+	io.WriteString(w, "<br><a href='/'>Try another one</a>")
+}
+
+func main() {
+	// redis store
+	s, err := captcha.NewRedisStore(&redis.Options{Addr: "localhost:6379", DB: 0}, captcha.Expiration, captcha.DefaultMaxRedisKeys, captcha.DefaultRedisPrefixKey)
+	if err != nil {
+		panic(err.Error())
+	}
+	captcha.SetCustomStore(s)
+
+	// http
+	http.HandleFunc("/", showFormHandler)
+	http.HandleFunc("/process", processFormHandler)
+	http.Handle("/captcha/", captcha.Server(captcha.StdWidth, captcha.StdHeight))
+	fmt.Println("Server is at localhost:8666")
+	if err := http.ListenAndServe("localhost:8666", nil); err != nil {
+		log.Fatal(err)
+	}
+}
+
+const formTemplateSrc = `<!doctype html>
+<head><title>Captcha Example</title></head>
+<body>
+<script>
+function setSrcQuery(e, q) {
+	var src  = e.src;
+	var p = src.indexOf('?');
+	if (p >= 0) {
+		src = src.substr(0, p);
+	}
+	e.src = src + "?" + q
+}
+
+function playAudio() {
+	var le = document.getElementById("lang");
+	var lang = le.options[le.selectedIndex].value;
+	var e = document.getElementById('audio')
+	setSrcQuery(e, "lang=" + lang)
+	e.style.display = 'block';
+	e.autoplay = 'true';
+	return false;
+}
+
+function changeLang() {
+	var e = document.getElementById('audio')
+	if (e.style.display == 'block') {
+		playAudio();
+	}
+}
+
+function reload() {
+	setSrcQuery(document.getElementById('image'), "reload=" + (new Date()).getTime());
+	setSrcQuery(document.getElementById('audio'), (new Date()).getTime());
+	return false;
+}
+</script>
+<select id="lang" onchange="changeLang()">
+	<option value="en">English</option>
+	<option value="ja">Japanese</option>
+	<option value="ru">Russian</option>
+	<option value="zh">Chinese</option>
+</select>
+<form action="/process" method=post>
+<p>Type the numbers you see in the picture below:</p>
+<p><img id=image src="/captcha/{{.CaptchaId}}.png" alt="Captcha image"></p>
+<a href="#" onclick="reload()">Reload</a> | <a href="#" onclick="playAudio()">Play Audio</a>
+<audio id=audio controls style="display:none" src="/captcha/{{.CaptchaId}}.wav" preload=none>
+  You browser doesn't support audio.
+  <a href="/captcha/download/{{.CaptchaId}}.wav">Download file</a> to play it in the external player.
+</audio>
+<input type=hidden name=captchaId value="{{.CaptchaId}}"><br>
+<input name=captchaSolution>
+<input type=submit value=Submit>
+</form>
+`
diff --git a/store_redis.go b/store_redis.go
@@ -0,0 +1,78 @@
+// Contributed 2020 by Hari
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package captcha
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/go-redis/redis"
+)
+
+const (
+	// DefaultMaxRedisKeys default max redis keys per expiration
+	DefaultMaxRedisKeys = 500000
+	// DefaultRedisPrefixKey default redis prefix key
+	DefaultRedisPrefixKey = "captcha"
+)
+
+// redisStore is an internal store for captcha ids and their values.
+type redisStore struct {
+	redisClient *redis.Client
+	expiration  time.Duration
+	maxKeys     int64
+	prefixKey   string
+}
+
+// NewRedisStore returns new Redis memory store
+func NewRedisStore(redisOptions *redis.Options, expiration time.Duration, maxKeys int64, prefixKey string) (Store, error) {
+	if redisOptions == nil {
+		return nil, fmt.Errorf("invalid redis options: %v", redisOptions)
+	}
+	s := new(redisStore)
+	s.redisClient = redis.NewClient(redisOptions)
+	s.expiration = expiration
+	s.maxKeys = maxKeys
+	if s.maxKeys <= 100 {
+		s.maxKeys = DefaultMaxRedisKeys
+	}
+	s.prefixKey = prefixKey
+	if s.prefixKey == "" {
+		s.prefixKey = DefaultRedisPrefixKey
+	}
+
+	return s, nil
+}
+
+func (s *redisStore) Set(id string, digits []byte) {
+	c, err := s.redisClient.DbSize().Result()
+	if err != nil {
+		panic(err)
+	}
+	if c > s.maxKeys {
+		panic(fmt.Errorf("to many keys > %v", s.maxKeys))
+	}
+
+	id = fmt.Sprintf("%s.%s", s.prefixKey, id)
+	_, err = s.redisClient.Get(id).Result()
+	if err == redis.Nil {
+		s.redisClient.Set(id, digits, s.expiration)
+	}
+}
+
+func (s *redisStore) Get(id string, clear bool) (digits []byte) {
+	id = fmt.Sprintf("%s.%s", s.prefixKey, id)
+	val, err := s.redisClient.Get(id).Result()
+	if err == redis.Nil {
+		return digits
+	}
+	digits = []byte(val)
+	if clear {
+		if err != redis.Nil {
+			s.redisClient.Del(id)
+		}
+	}
+	return digits
+}
diff --git a/store_redis_test.go b/store_redis_test.go
@@ -0,0 +1,66 @@
+// Contributed 2020 by Hari
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package captcha
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/go-redis/redis"
+)
+
+func TestRedisSetGet(t *testing.T) {
+	s, err := NewRedisStore(&redis.Options{Addr: "localhost:6379", DB: 0}, 1*time.Minute, DefaultMaxRedisKeys, DefaultRedisPrefixKey)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	id := "redis-id-no-clear"
+	d := RandomDigits(10)
+	s.Set(id, d)
+	d2 := s.Get(id, false)
+	if d2 == nil || !bytes.Equal(d, d2) {
+		t.Errorf("saved %v, getDigits returned got %v", d, d2)
+	}
+}
+
+func TestRedisGetClear(t *testing.T) {
+	s, err := NewRedisStore(&redis.Options{Addr: "localhost:6379", DB: 0}, Expiration, DefaultMaxRedisKeys, DefaultRedisPrefixKey)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	id := "redis-id"
+	d := RandomDigits(10)
+	s.Set(id, d)
+	d2 := s.Get(id, true)
+	if d2 == nil || !bytes.Equal(d, d2) {
+		t.Errorf("saved %v, getDigits returned got %v", d, d2)
+	}
+	d2 = s.Get(id, false)
+	if d2 != nil {
+		t.Errorf("getDigitClear didn't clear (%q=%v)", id, d2)
+	}
+}
+
+func BenchmarkRedisMaxKeys(b *testing.B) {
+	maxKeys := 101
+
+	b.StopTimer()
+	d := RandomDigits(10)
+	s, err := NewRedisStore(&redis.Options{Addr: "localhost:6379", DB: 0}, 1*time.Minute, int64(maxKeys), DefaultRedisPrefixKey)
+	if err != nil {
+		b.Errorf(err.Error())
+	}
+	ids := make([]string, maxKeys)
+	for i := range ids {
+		ids[i] = randomId()
+	}
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < maxKeys; j++ {
+			s.Set(ids[j], d)
+		}
+	}
+}