From dca0adec81c06ea32e2f20de766f72f8fa76ccf4 Mon Sep 17 00:00:00 2001
From: ItsOnlyBinary <git@itsonlybinary.com>
Date: Tue, 2 Feb 2021 18:24:17 +0000
Subject: [PATCH] Add recaptcha cache so multiple networks can use the same
 response

---
 main.go                                      |  4 ++
 pkg/recaptcha/recaptcha.go                   | 67 +++++++++++++++++++-
 pkg/webircgateway/client_command_handlers.go |  2 +-
 3 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/main.go b/main.go
index efd812b..b025672 100644
--- a/main.go
+++ b/main.go
@@ -10,6 +10,7 @@ import (
 	"sync"
 	"syscall"
 
+	"github.com/kiwiirc/webircgateway/pkg/recaptcha"
 	"github.com/kiwiirc/webircgateway/pkg/webircgateway"
 )
 
@@ -39,6 +40,9 @@ func main() {
 		os.Exit(1)
 	}
 
+	// Start recaptcha cleanup function
+	recaptcha.Init()
+
 	runGateway(*configFile, *startSection)
 }
 
diff --git a/pkg/recaptcha/recaptcha.go b/pkg/recaptcha/recaptcha.go
index 2d602fc..488e2e8 100644
--- a/pkg/recaptcha/recaptcha.go
+++ b/pkg/recaptcha/recaptcha.go
@@ -7,9 +7,21 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"sync"
 	"time"
 )
 
+var cacheVerified sync.Map
+var cacheLife, _ = time.ParseDuration("90s")
+var cacheFrequency, _ = time.ParseDuration("10m")
+var cacheTicker = time.NewTicker(cacheFrequency)
+
+// CacheItem represents an item in response cache
+type CacheItem struct {
+	created    int64
+	remoteAddr string
+}
+
 // R type represents an object of Recaptcha and has public property Secret,
 // which is secret obtained from google recaptcha tool admin interface
 type R struct {
@@ -24,9 +36,55 @@ type googleResponse struct {
 	ErrorCodes []string `json:"error-codes"`
 }
 
+// Init starts recpatcha response cache cleanup
+func Init() {
+	go func() {
+		for range cacheTicker.C {
+			cleanCache()
+		}
+	}()
+}
+
+func cleanCache() {
+	cacheVerified.Range(func(key interface{}, value interface{}) bool {
+		cacheItem := value.(CacheItem)
+		expired := time.Now().Unix() - int64(cacheLife.Seconds())
+		if cacheItem.created < expired {
+			cacheVerified.Delete(key)
+		}
+		return true
+	})
+}
+
+func verifyCached(response string, remoteAddr string) bool {
+	cacheInterface, ok := cacheVerified.Load(response)
+	if !ok {
+		// Not in cache
+		return false
+	}
+	cacheItem := cacheInterface.(CacheItem)
+	if cacheItem.remoteAddr != remoteAddr {
+		// None matching remoteAddr
+		return false
+	}
+	expired := time.Now().Unix() - int64(cacheLife.Seconds())
+	if cacheItem.created < expired {
+		// Cached response expired
+		cacheVerified.Delete(remoteAddr)
+		return false
+	}
+
+	// Valid response
+	return true
+}
+
 // VerifyResponse is a method similar to `Verify`; but doesn't parse the form for you.  Useful if
 // you're receiving the data as a JSON object from a javascript app or similar.
-func (r *R) VerifyResponse(response string) bool {
+func (r *R) VerifyResponse(response string, remoteAddr string) bool {
+	if verifyCached(response, remoteAddr) {
+		// Response is cached and still valid
+		return true
+	}
 	r.lastError = make([]string, 1)
 	client := &http.Client{Timeout: 20 * time.Second}
 	resp, err := client.PostForm(r.URL,
@@ -47,7 +105,12 @@ func (r *R) VerifyResponse(response string) bool {
 		r.lastError = append(r.lastError, err.Error())
 		return false
 	}
-	if !gr.Success {
+	if gr.Success {
+		cacheVerified.Store(response, CacheItem{
+			created:    time.Now().Unix(),
+			remoteAddr: remoteAddr,
+		})
+	} else {
 		r.lastError = append(r.lastError, gr.ErrorCodes...)
 	}
 	return gr.Success
diff --git a/pkg/webircgateway/client_command_handlers.go b/pkg/webircgateway/client_command_handlers.go
index d895673..fa6dcf3 100644
--- a/pkg/webircgateway/client_command_handlers.go
+++ b/pkg/webircgateway/client_command_handlers.go
@@ -193,7 +193,7 @@ func (c *Client) ProcessLineFromClient(line string) (string, error) {
 				Secret: c.Gateway.Config.ReCaptchaSecret,
 			}
 
-			verified = captcha.VerifyResponse(message.Params[0])
+			verified = captcha.VerifyResponse(message.Params[0], c.RemoteAddr)
 		}
 
 		if !verified {