option to return ErrSkip and ErrBlock from validator

go.mod

@@ -1,5 +1,7 @@
 module github.com/drone/drone-go
 
+go 1.14
+
 require (
 	github.com/99designs/httpsignatures-go v0.0.0-20170731043157-88528bf4ca7e
 	github.com/google/go-cmp v0.2.0

go.sum

@@ -0,0 +1,4 @@
+github.com/99designs/httpsignatures-go v0.0.0-20170731043157-88528bf4ca7e h1:rl2Aq4ZODqTDkeSqQBy+fzpZPamacO1Srp8zq7jf2Sc=
+github.com/99designs/httpsignatures-go v0.0.0-20170731043157-88528bf4ca7e/go.mod h1:Xa6lInWHNQnuWoF0YPSsx+INFA9qk7/7pTjwb3PInkY=
+github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=

plugin/validator/client.go

@@ -17,6 +17,7 @@ package validator
 import (
 	"context"
 
+	"github.com/drone/drone-go/drone"
 	"github.com/drone/drone-go/plugin/internal/client"
 )
 
@@ -34,5 +35,14 @@ type pluginClient struct {
 }
 
 func (c *pluginClient) Validate(ctx context.Context, in *Request) error {
-	return c.client.Do(in, nil)
+	err := c.client.Do(in, nil)
+	if xerr, ok := err.(*drone.Error); ok {
+		if xerr.Code == 498 {
+			return ErrSkip
+		}
+		if xerr.Code == 499 {
+			return ErrBlock
+		}
+	}
+	return err
 }

plugin/validator/client_test.go

@@ -0,0 +1,51 @@
+// Copyright 2018 Drone.IO Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package validator
+
+// import (
+// 	"bytes"
+// 	"context"
+// 	"io/ioutil"
+// 	"net/http"
+// 	"testing"
+// )
+
+// var noContext = context.Background()
+
+// func TestErrSkip(t *testing.T) {
+// 	client := http.Client{}
+// 	client.Transport = roundTripFunc(func(r *http.Request) (*http.Response, error) {
+// 		buf := bytes.NewBuffer(nil)
+// 		buf.WriteString("skip")
+// 		return &http.Response{
+// 			Body:       ioutil.NopCloser(buf),
+// 			StatusCode: 498,
+// 		}, nil
+// 	})
+
+// 	plugin := Client("http://localhost", "top-secret", false)
+// 	plugin.(*pluginClient).client.Client = &client
+
+// 	err := plugin.Validate(noContext, &Request{})
+// 	if err != ErrSkip {
+// 		t.Errorf("Expect skip error, got %v", err)
+// 	}
+// }
+
+// type roundTripFunc func(r *http.Request) (*http.Response, error)
+
+// func (s roundTripFunc) RoundTrip(r *http.Request) (*http.Response, error) {
+// 	return s(r)
+// }

plugin/validator/handler.go

@@ -90,6 +90,16 @@ func (p *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if err == ErrSkip {
+		w.WriteHeader(498)
+		return
+	}
+
+	if err == ErrBlock {
+		w.WriteHeader(499)
+		return
+	}
+
 	// The error should be converted to a drone.Error so that
 	// it can be marshaled to JSON.
 	if _, ok := err.(*drone.Error); !ok {

plugin/validator/handler_test.go

@@ -98,6 +98,68 @@ func TestHandler_Error(t *testing.T) {
 	}
 }
 
+func TestHandler_ErrorSkip(t *testing.T) {
+	key := "xVKAGlWQiY3sOp8JVc0nbuNId3PNCgWh"
+
+	buf := new(bytes.Buffer)
+	json.NewEncoder(buf).Encode(&Request{
+		Config: drone.Config{
+			Data: "{kind: pipeline, type: docker}",
+		},
+	})
+
+	res := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/", buf)
+	req.Header.Add("Date", time.Now().UTC().Format(http.TimeFormat))
+
+	err := httpsignatures.DefaultSha256Signer.AuthRequest("hmac-key", key, req)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	err = ErrSkip
+	plugin := &mockPlugin{err: err}
+
+	handler := Handler(key, plugin, nil)
+	handler.ServeHTTP(res, req)
+
+	if got, want := res.Code, 498; got != want {
+		t.Errorf("Want status code %d, got %d", want, got)
+	}
+}
+
+func TestHandler_ErrorBlock(t *testing.T) {
+	key := "xVKAGlWQiY3sOp8JVc0nbuNId3PNCgWh"
+
+	buf := new(bytes.Buffer)
+	json.NewEncoder(buf).Encode(&Request{
+		Config: drone.Config{
+			Data: "{kind: pipeline, type: docker}",
+		},
+	})
+
+	res := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/", buf)
+	req.Header.Add("Date", time.Now().UTC().Format(http.TimeFormat))
+
+	err := httpsignatures.DefaultSha256Signer.AuthRequest("hmac-key", key, req)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	err = ErrBlock
+	plugin := &mockPlugin{err: err}
+
+	handler := Handler(key, plugin, nil)
+	handler.ServeHTTP(res, req)
+
+	if got, want := res.Code, 499; got != want {
+		t.Errorf("Want status code %d, got %d", want, got)
+	}
+}
+
 func TestHandler_MissingSignature(t *testing.T) {
 	res := httptest.NewRecorder()
 	req := httptest.NewRequest("GET", "/", nil)

plugin/validator/validater.go

@@ -16,6 +16,7 @@ package validator
 
 import (
 	"context"
+	"errors"
 
 	"github.com/drone/drone-go/drone"
 )
@@ -23,6 +24,14 @@ import (
 // V1 is version 1 of the validator API
 const V1 = "application/vnd.drone.validate.v1+json"
 
+// ErrSkip is returned when the build should be skipped
+// instead of throwing an error.
+var ErrSkip = errors.New("skip")
+
+// ErrBlock is returned when the build should be blocked
+// instead of throwing an error.
+var ErrBlock = errors.New("block")
+
 type (
 	// Request defines a validator request.
 	Request struct {