Merge pull request #5469 from filecoin-project/feat/faucet-captcha

Add spam protection to fountain

cmd/lotus-fountain/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"html/template"
 	"net"
 	"net/http"
 	"os"
@@ -68,6 +69,10 @@ var runCmd = &cli.Command{
 			EnvVars: []string{"LOTUS_FOUNTAIN_AMOUNT"},
 			Value:   "50",
 		},
+		&cli.Float64Flag{
+			Name:  "captcha-threshold",
+			Value: 0.5,
+		},
 	},
 	Action: func(cctx *cli.Context) error {
 		sendPerRequest, err := types.ParseFIL(cctx.String("amount"))
@@ -107,11 +112,13 @@ var runCmd = &cli.Command{
 				WalletRate:  15 * time.Minute,
 				WalletBurst: 2,
 			}),
+			recapThreshold: cctx.Float64("captcha-threshold"),
 		}
 
-		http.Handle("/", http.FileServer(rice.MustFindBox("site").HTTPBox()))
-		http.HandleFunc("/send", h.send)
-
+		box := rice.MustFindBox("site")
+		http.Handle("/", http.FileServer(box.HTTPBox()))
+		http.HandleFunc("/funds.html", prepFundsHtml(box))
+		http.Handle("/send", h)
 		fmt.Printf("Open http://%s\n", cctx.String("front"))
 
 		go func() {
@@ -123,6 +130,17 @@ var runCmd = &cli.Command{
 	},
 }
 
+func prepFundsHtml(box *rice.Box) http.HandlerFunc {
+	tmpl := template.Must(template.New("funds").Parse(box.MustString("funds.html")))
+	return func(w http.ResponseWriter, r *http.Request) {
+		err := tmpl.Execute(w, os.Getenv("RECAPTCHA_SITE_KEY"))
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadGateway)
+			return
+		}
+	}
+}
+
 type handler struct {
 	ctx context.Context
 	api api.FullNode
@@ -130,15 +148,45 @@ type handler struct {
 	from           address.Address
 	sendPerRequest types.FIL
 
-	limiter *Limiter
+	limiter        *Limiter
+	recapThreshold float64
 }
 
-func (h *handler) send(w http.ResponseWriter, r *http.Request) {
+func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "only POST is allowed", http.StatusBadRequest)
+		return
+	}
+
+	reqIP := r.Header.Get("X-Real-IP")
+	if reqIP == "" {
+		h, _, err := net.SplitHostPort(r.RemoteAddr)
+		if err != nil {
+			log.Errorf("could not get ip from: %s, err: %s", r.RemoteAddr, err)
+		}
+		reqIP = h
+	}
+
+	capResp, err := VerifyToken(r.FormValue("g-recaptcha-response"), reqIP)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadGateway)
+		return
+	}
+	if !capResp.Success || capResp.Score < h.recapThreshold {
+		log.Infow("spam", "capResp", capResp)
+		http.Error(w, "spam protection", http.StatusUnprocessableEntity)
+		return
+	}
+
 	to, err := address.NewFromString(r.FormValue("address"))
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
+	if to == address.Undef {
+		http.Error(w, "empty address", http.StatusBadRequest)
+		return
+	}
 
 	// Limit based on wallet address
 	limiter := h.limiter.GetWalletLimiter(to.String())
@@ -148,15 +196,6 @@ func (h *handler) send(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Limit based on IP
-
-	reqIP := r.Header.Get("X-Real-IP")
-	if reqIP == "" {
-		h, _, err := net.SplitHostPort(r.RemoteAddr)
-		if err != nil {
-			log.Errorf("could not get ip from: %s, err: %s", r.RemoteAddr, err)
-		}
-		reqIP = h
-	}
 	if i := net.ParseIP(reqIP); i != nil && i.IsLoopback() {
 		log.Errorf("rate limiting localhost: %s", reqIP)
 	}

cmd/lotus-fountain/recaptcha.go

@@ -0,0 +1,73 @@
+// From https://github.com/lukasaron/recaptcha
+// BLS-3 Licensed
+// Copyright (c) 2020, Lukas Aron
+// Modified by Kubuxu
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+)
+
+// content type for communication with the verification server.
+const (
+	contentType = "application/json"
+)
+
+// VerifyURL defines the endpoint which is called when a token needs to be verified.
+var (
+	VerifyURL, _ = url.Parse("https://www.google.com/recaptcha/api/siteverify")
+)
+
+// Response defines the response format from the verification endpoint.
+type Response struct {
+	Success            bool      `json:"success"`          // status of the verification
+	TimeStamp          time.Time `json:"challenge_ts"`     // timestamp of the challenge load (ISO format)
+	HostName           string    `json:"hostname"`         // the hostname of the site where the reCAPTCHA was solved
+	Score              float64   `json:"score"`            // the score for this request (0.0 - 1.0)
+	Action             string    `json:"action"`           // the action name for this request
+	ErrorCodes         []string  `json:"error-codes"`      // error codes
+	AndroidPackageName string    `json:"apk_package_name"` // android related only
+}
+
+// VerifyToken function implements the basic logic of verification of ReCaptcha token that is usually created
+// on the user site (front-end) and then sent to verify on the server side (back-end).
+// To provide a successful verification process the secret key is required. Based on the security recommendations
+// the key has to be passed as an environmental variable SECRET_KEY.
+//
+// Token parameter is required, however remoteIP is optional.
+func VerifyToken(token, remoteIP string) (Response, error) {
+	resp := Response{}
+	if len(token) == 0 {
+		resp.ErrorCodes = []string{"no-token"}
+		return resp, nil
+	}
+
+	q := url.Values{}
+	q.Add("secret", os.Getenv("RECAPTCHA_SECRET_KEY"))
+	q.Add("response", token)
+	q.Add("remoteip", remoteIP)
+
+	var u *url.URL
+	{
+		verifyCopy := *VerifyURL
+		u = &verifyCopy
+	}
+	u.RawQuery = q.Encode()
+	r, err := http.Post(u.String(), contentType, nil)
+	if err != nil {
+		return resp, err
+	}
+
+	b, err := ioutil.ReadAll(r.Body)
+	_ = r.Body.Close() // close immediately after reading finished
+	if err != nil {
+		return resp, err
+	}
+
+	return resp, json.Unmarshal(b, &resp)
+}

cmd/lotus-fountain/site/funds.html

@@ -3,6 +3,13 @@
 <head>
     <title>Sending Funds - Lotus Fountain</title>
     <link rel="stylesheet" type="text/css" href="main.css">
+	<script src="https://www.google.com/recaptcha/api.js"></script>
+	<script>
+   		function onSubmit(token) {
+     	document.getElementById("funds-form").submit();
+   	}
+	</script>
+
 </head>
 <body>
 <div class="Index">
@@ -11,10 +18,13 @@
             [SENDING FUNDS]
         </div>
         <div class="Index-node">
-            <form action='/send' method='get'>
+            <form action='/send' method='post' id='funds-form'>
                 <span>Enter destination address:</span>
-                <input type='text' name='address' style="width: 300px">
-                <button type='submit'>Send Funds</button>
+				<input type='text' name='address' style="width: 300px">
+				<button class="g-recaptcha" 
+						data-sitekey="{{ . }}"
+						data-callback='onSubmit' 
+						data-action='submit'>Send Funds</button>
             </form>
         </div>
     </div>

go.mod

@@ -121,6 +121,7 @@ require (
 	github.com/multiformats/go-multiaddr-dns v0.2.0
 	github.com/multiformats/go-multibase v0.0.3
 	github.com/multiformats/go-multihash v0.0.14
+	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/opentracing/opentracing-go v1.2.0
 	github.com/polydawn/refmt v0.0.0-20190809202753-05966cbd336a
 	github.com/prometheus/client_golang v1.6.0
@@ -145,6 +146,7 @@ require (
 	golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f
 	golang.org/x/time v0.0.0-20191024005414-555d28b269f0
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
+	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
 	gopkg.in/cheggaaa/pb.v1 v1.0.28
 	gotest.tools v2.2.0+incompatible
 )

go.sum

@@ -1228,6 +1228,8 @@ github.com/nats-io/nkeys v0.1.3/go.mod h1:xpnFELMwJABBLVhffcfd1MZx6VsNRFpEugbxzi
 github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
 github.com/neelance/astrewrite v0.0.0-20160511093645-99348263ae86/go.mod h1:kHJEU3ofeGjhHklVoIGuVj85JJwZ6kWPaJwCIxgnFmo=
 github.com/neelance/sourcemap v0.0.0-20151028013722-8c68805598ab/go.mod h1:Qr6/a/Q4r9LP1IltGz7tA7iOK1WonHEYhu1HRBA7ZiM=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/nikkolasg/hexjson v0.0.0-20181101101858-78e39397e00c h1:5bFTChQxSKNwy8ALwOebjekYExl9HTT9urdawqC95tA=
 github.com/nikkolasg/hexjson v0.0.0-20181101101858-78e39397e00c/go.mod h1:7qN3Y0BvzRUf4LofcoJplQL10lsFDb4PYlePTVwrP28=
 github.com/nkovacs/streamquote v0.0.0-20170412213628-49af9bddb229 h1:E2B8qYyeSgv5MXpmzZXRNp8IAQ4vjxIjhpAf5hv/tAg=
@@ -1918,6 +1920,8 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
+gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/cheggaaa/pb.v1 v1.0.25/go.mod h1:V/YB90LKu/1FcN3WVnfiiE5oMCibMjukxqG/qStrOgw=
 gopkg.in/cheggaaa/pb.v1 v1.0.28 h1:n1tBJnnK2r7g9OW2btFH91V92STTUevLXYFb8gy9EMk=
 gopkg.in/cheggaaa/pb.v1 v1.0.28/go.mod h1:V/YB90LKu/1FcN3WVnfiiE5oMCibMjukxqG/qStrOgw=