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Abuse Protection for webhooks (#491)
* First pass at supporting receiver based webhook abuse protection * Adding client test for new status codes. * adding options to set the GET and OPTIONS function handlers. * adding docs for abuse protection * don't drop encoding checking * fix unit tests for unknown encoding * allow nil event to be delivered if receiver wants Signed-off-by: Scott Nichols <snichols@vmware.com>
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Scott Nichols
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May 19, 2020
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "log" | ||
|
|
||
| cloudevents "github.com/cloudevents/sdk-go/v2" | ||
| ) | ||
|
|
||
| func main() { | ||
| ctx := context.Background() | ||
| p, err := cloudevents.NewHTTP( | ||
| cloudevents.WithDefaultOptionsHandlerFunc([]string{"POST", "OPTIONS"}, 100, []string{"http://localhost:8181"}, true), | ||
| ) | ||
| if err != nil { | ||
| log.Fatalf("failed to create protocol: %s", err.Error()) | ||
| } | ||
|
|
||
| c, err := cloudevents.NewClient(p) | ||
| if err != nil { | ||
| log.Fatalf("failed to create client, %v", err) | ||
| } | ||
|
|
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| log.Printf("will listen on :8080\n") | ||
| log.Fatalf("failed to start receiver: %s", c.StartReceiver(ctx, receive)) | ||
| } | ||
|
|
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| func receive(ctx context.Context, event cloudevents.Event) { | ||
| fmt.Printf("%s", event) | ||
| } | ||
|
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| // | ||
| // Testing with: | ||
| // | ||
| // PORT=8181 go run ./cmd/tools/http/raw/ | ||
| // | ||
| // curl http://localhost:8080 -v -X OPTIONS -H "Origin: http://example.com" -H "WebHook-Request-Origin: http://example.com" -H "WebHook-Request-Callback: http://localhost:8181/do-this?now=true" | ||
| // |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,34 @@ | ||
| package main | ||
|
|
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| import ( | ||
| "fmt" | ||
| "log" | ||
| "net/http" | ||
| "net/http/httputil" | ||
|
|
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| "github.com/kelseyhightower/envconfig" | ||
| ) | ||
|
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| type RawHTTP struct { | ||
| Port int `envconfig:"PORT" default:"8080"` | ||
| } | ||
|
|
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| func (raw *RawHTTP) ServeHTTP(w http.ResponseWriter, r *http.Request) { | ||
| w.WriteHeader(http.StatusOK) | ||
| if reqBytes, err := httputil.DumpRequest(r, true); err == nil { | ||
| log.Printf("Raw HTTP Request:\n%+v", string(reqBytes)) | ||
| _, _ = w.Write(reqBytes) | ||
| } else { | ||
| log.Printf("Failed to call DumpRequest: %s", err) | ||
| } | ||
| fmt.Println("------------------------------") | ||
| } | ||
|
|
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| func main() { | ||
| var env RawHTTP | ||
| if err := envconfig.Process("", &env); err != nil { | ||
| log.Fatalf("Failed to process env var: %s", err) | ||
| } | ||
| log.Printf("Starting listening on :%d\n", env.Port) | ||
| log.Println(http.ListenAndServe(fmt.Sprintf(":%d", env.Port), &env)) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,121 @@ | ||
| package http | ||
|
|
||
| import ( | ||
| "context" | ||
| cecontext "github.com/cloudevents/sdk-go/v2/context" | ||
| "go.uber.org/zap" | ||
| "net/http" | ||
| "strconv" | ||
| "strings" | ||
| ) | ||
|
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| type WebhookConfig struct { | ||
| AllowedMethods []string // defaults to POST | ||
| AllowedRate *int | ||
| AutoACKCallback bool | ||
| AllowedOrigins []string | ||
| } | ||
|
|
||
| const ( | ||
| DefaultAllowedRate = 1000 | ||
| ) | ||
|
|
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| // TODO: implement rate limiting. | ||
| // Throttling is indicated by requests being rejected using HTTP status code 429 Too Many Requests. | ||
| // TODO: use this if Webhook Request Origin has been turned on. | ||
| // Inbound requests should be rejected if Allowed Origins is required by SDK. | ||
|
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| func (p *Protocol) OptionsHandler(rw http.ResponseWriter, req *http.Request) { | ||
| if req.Method != http.MethodOptions || p.WebhookConfig == nil { | ||
| rw.WriteHeader(http.StatusMethodNotAllowed) | ||
| return | ||
| } | ||
|
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| headers := make(http.Header) | ||
|
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| // The spec does not say we need to validate the origin, just the request origin. | ||
| // After the handshake, we will validate the origin. | ||
| if origin, ok := p.ValidateRequestOrigin(req); !ok { | ||
| rw.WriteHeader(http.StatusBadRequest) | ||
| return | ||
| } else { | ||
| headers.Set("WebHook-Allowed-Origin", origin) | ||
| } | ||
|
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| allowedRateRequired := false | ||
| if _, ok := req.Header[http.CanonicalHeaderKey("WebHook-Request-Rate")]; ok { | ||
| // must send WebHook-Allowed-Rate | ||
| allowedRateRequired = true | ||
| } | ||
|
|
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| if p.WebhookConfig.AllowedRate != nil { | ||
| headers.Set("WebHook-Allowed-Rate", strconv.Itoa(*p.WebhookConfig.AllowedRate)) | ||
| } else if allowedRateRequired { | ||
| headers.Set("WebHook-Allowed-Rate", strconv.Itoa(DefaultAllowedRate)) | ||
| } | ||
|
|
||
| if len(p.WebhookConfig.AllowedMethods) > 0 { | ||
| headers.Set("Allow", strings.Join(p.WebhookConfig.AllowedMethods, ", ")) | ||
| } else { | ||
| headers.Set("Allow", http.MethodPost) | ||
| } | ||
|
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| cb := req.Header.Get("WebHook-Request-Callback") | ||
| if cb != "" { | ||
| if p.WebhookConfig.AutoACKCallback { | ||
| go func() { | ||
| reqAck, err := http.NewRequest(http.MethodPost, cb, nil) | ||
| if err != nil { | ||
| cecontext.LoggerFrom(req.Context()).Errorw("OPTIONS handler failed to create http request attempting to ack callback.", zap.Error(err), zap.String("callback", cb)) | ||
| return | ||
| } | ||
|
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| // Write out the headers. | ||
| for k := range headers { | ||
| reqAck.Header.Set(k, headers.Get(k)) | ||
| } | ||
|
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| _, err = http.DefaultClient.Do(reqAck) | ||
| if err != nil { | ||
| cecontext.LoggerFrom(req.Context()).Errorw("OPTIONS handler failed to ack callback.", zap.Error(err), zap.String("callback", cb)) | ||
| return | ||
| } | ||
| }() | ||
| return | ||
| } else { | ||
| cecontext.LoggerFrom(req.Context()).Infof("ACTION REQUIRED: Please validate web hook request callback: %q", cb) | ||
| // TODO: what to do pending https://github.com/cloudevents/spec/issues/617 | ||
| return | ||
| } | ||
| } | ||
|
|
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| // Write out the headers. | ||
| for k := range headers { | ||
| rw.Header().Set(k, headers.Get(k)) | ||
| } | ||
| } | ||
|
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| func (p *Protocol) ValidateRequestOrigin(req *http.Request) (string, bool) { | ||
| return p.validateOrigin(req.Header.Get("WebHook-Request-Origin")) | ||
| } | ||
|
|
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| func (p *Protocol) ValidateOrigin(req *http.Request) (string, bool) { | ||
| return p.validateOrigin(req.Header.Get("Origin")) | ||
| } | ||
|
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| func (p *Protocol) validateOrigin(ro string) (string, bool) { | ||
| cecontext.LoggerFrom(context.TODO()).Infow("Validating origin.", zap.String("origin", ro)) | ||
|
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| for _, ao := range p.WebhookConfig.AllowedOrigins { | ||
| if ao == "*" { | ||
| return ao, true | ||
| } | ||
| // TODO: it is not clear what the rules for allowed hosts are. | ||
| // Need to find docs for this. For now, test for prefix. | ||
| if strings.HasPrefix(ro, ao) { | ||
| return ao, true | ||
| } | ||
| } | ||
|
|
||
| return ro, false | ||
| } |
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