upstream validation: implementation, first try (#21)

config/backend.go

@@ -13,6 +13,9 @@ type Backend struct {
 	Path           string   `hcl:"path,optional"`
 	Timeout        string   `hcl:"timeout,optional"`
 	TTFBTimeout    string   `hcl:"ttfb_timeout,optional"`
+	SwaggerDef     string   `hcl:"swagger_definition,optional"`
+	ValidateReq    bool     `hcl:"validate_request,optional"`
+	ValidateRes    bool     `hcl:"validate_response,optional"`
 }
 
 // Merge overrides the left backend configuration and returns a new instance.
@@ -62,5 +65,17 @@ func (b *Backend) Merge(other *Backend) (*Backend, []hcl.Body) {
 		result.TTFBTimeout = other.TTFBTimeout
 	}
 
+	if other.SwaggerDef != "" {
+		result.SwaggerDef = other.SwaggerDef
+	}
+
+	if other.ValidateReq {
+		result.ValidateReq = other.ValidateReq
+	}
+
+	if other.ValidateRes {
+		result.ValidateRes = other.ValidateRes
+	}
+
 	return &result, bodies
 }

config/runtime/handler.go

@@ -80,6 +80,9 @@ func BuildEntrypointHandlers(conf *config.Gateway, httpConf *HTTPConfig, log *lo
 				Path:           beConf.Path,
 				Timeout:        t,
 				TTFBTimeout:    ttfbt,
+				SwaggerDef:     beConf.SwaggerDef,
+				ValidateReq:    beConf.ValidateReq,
+				ValidateRes:    beConf.ValidateRes,
 			}, log, conf.Context)
 			if err != nil {
 				log.Fatal(err)
@@ -193,6 +196,9 @@ func BuildEntrypointHandlers(conf *config.Gateway, httpConf *HTTPConfig, log *lo
 						Path:           beConf.Path,
 						Timeout:        t,
 						TTFBTimeout:    ttfbt,
+						SwaggerDef:     beConf.SwaggerDef,
+						ValidateReq:    beConf.ValidateReq,
+						ValidateRes:    beConf.ValidateRes,
 					}, log, conf.Context)
 					if err != nil {
 						log.Fatal(err)
@@ -262,6 +268,9 @@ func BuildEntrypointHandlers(conf *config.Gateway, httpConf *HTTPConfig, log *lo
 					Path:           beConf.Path,
 					Timeout:        t,
 					TTFBTimeout:    ttfbt,
+					SwaggerDef:     beConf.SwaggerDef,
+					ValidateReq:    beConf.ValidateReq,
+					ValidateRes:    beConf.ValidateRes,
 				}, log, conf.Context)
 				if err != nil {
 					log.Fatal(err)
@@ -479,6 +488,9 @@ func newInlineBackend(evalCtx *hcl.EvalContext, inlineDef hcl.Body, cors *config
 		Path:           beConf.Path,
 		Timeout:        t,
 		TTFBTimeout:    ttfbt,
+		SwaggerDef:     beConf.SwaggerDef,
+		ValidateReq:    beConf.ValidateReq,
+		ValidateRes:    beConf.ValidateRes,
 	}, log, evalCtx)
 	return proxy, beConf, err
 }

errors/code.go

@@ -30,6 +30,12 @@ const (
 	BasicAuthFailed
 )
 
+const (
+	UpstreamRequestValidationFailed Code = 6000 + iota
+	UpstreamResponseValidationFailed
+	UpstreamResponseBufferingFailed
+)
+
 var codes = map[Code]string{
 	// 1xxx
 	Server:         "Server error",
@@ -51,6 +57,10 @@ var codes = map[Code]string{
 	AuthorizationRequired: "Authorization required",
 	AuthorizationFailed:   "Authorization failed",
 	BasicAuthFailed:       "Unauthorized",
+	// 6xxx
+	UpstreamRequestValidationFailed:  "Upstream request validation failed",
+	UpstreamResponseValidationFailed: "Upstream response validation failed",
+	UpstreamResponseBufferingFailed:  "Upstream response buffering failed",
 }
 
 type Code int

handler/proxy.go

@@ -6,14 +6,17 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"math"
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
 	"time"
 
+	"github.com/getkin/kin-openapi/openapi3filter"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/net/http/httpguts"
@@ -52,7 +55,8 @@ type ProxyOptions struct {
 	ConnectTimeout, Timeout, TTFBTimeout time.Duration
 	Context                              []hcl.Body
 	BackendName                          string
-	Hostname, Origin, Path               string
+	Hostname, Origin, Path, SwaggerDef   string
+	ValidateReq, ValidateRes             bool
 	CORS                                 *CORSOptions
 }
 
@@ -156,6 +160,44 @@ func (p *Proxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	p.upstreamLog.ServeHTTP(rw, req, logging.RoundtripHandlerFunc(p.roundtrip))
 }
 
+func (p *Proxy) preparetRequestValidatation(outreq *http.Request) (context.Context, *openapi3filter.Route, *openapi3filter.RequestValidationInput, error) {
+	if p.options.ValidateReq || p.options.ValidateRes {
+		dir, err := os.Getwd()
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		router := openapi3filter.NewRouter().WithSwaggerFromFile(dir + "/" + p.options.SwaggerDef)
+		validationCtx := context.Background()
+		route, pathParams, _ := router.FindRoute(outreq.Method, outreq.URL)
+
+		requestValidationInput := &openapi3filter.RequestValidationInput{
+			Request:    outreq,
+			PathParams: pathParams,
+			Route:      route,
+		}
+		return validationCtx, route, requestValidationInput, nil
+	}
+	return nil, nil, nil, nil
+}
+
+func (p *Proxy) prepareResponseValidatation(requestValidationInput *openapi3filter.RequestValidationInput, res *http.Response) (*openapi3filter.ResponseValidationInput, []byte, error) {
+	if p.options.ValidateRes {
+		responseValidationInput := &openapi3filter.ResponseValidationInput{
+			RequestValidationInput: requestValidationInput,
+			Status:                 res.StatusCode,
+			Header:                 res.Header,
+			Options:                &openapi3filter.Options{IncludeResponseStatus: true /* undefined response codes are invalid */},
+		}
+		body, err := ioutil.ReadAll(res.Body)
+		if err != nil {
+			return nil, nil, err
+		}
+		responseValidationInput.SetBodyBytes(body)
+		return responseValidationInput, body, nil
+	}
+	return nil, nil, nil
+}
+
 func (p *Proxy) roundtrip(rw http.ResponseWriter, req *http.Request) {
 	ctx := req.Context()
 	if p.options.Timeout > 0 {
@@ -203,6 +245,23 @@ func (p *Proxy) roundtrip(rw http.ResponseWriter, req *http.Request) {
 		outreq.Header.Set("X-Forwarded-For", clientIP)
 	}
 
+	validationCtx, route, requestValidationInput, err := p.preparetRequestValidatation(outreq)
+	if err != nil {
+		// this only happens if os.Getwd() fails
+		// TODO: use error template from parent endpoint>api>server
+		p.log.WithField("upstream request validation", err).Error()
+		couperErr.DefaultJSON.ServeError(couperErr.UpstreamRequestValidationFailed).ServeHTTP(rw, req)
+		return
+	}
+	if (p.options.ValidateReq) {
+		if err := openapi3filter.ValidateRequest(validationCtx, requestValidationInput); err != nil {
+			// TODO: use error template from parent endpoint>api>server
+			p.log.WithField("upstream request validation", err).Error()
+			couperErr.DefaultJSON.ServeError(couperErr.UpstreamRequestValidationFailed).ServeHTTP(rw, req)
+			return
+		}
+	}
+
 	res, err := p.transport.RoundTrip(outreq)
 	roundtripInfo := req.Context().Value(request.RoundtripInfo).(*logging.RoundtripInfo)
 	roundtripInfo.BeReq, roundtripInfo.BeResp, roundtripInfo.Err = outreq, res, err
@@ -212,6 +271,26 @@ func (p *Proxy) roundtrip(rw http.ResponseWriter, req *http.Request) {
 		return
 	}
 
+	responseValidationInput, body, err := p.prepareResponseValidatation(requestValidationInput, res)
+	if err != nil {
+		// TODO: use error template from parent endpoint>api>server
+		p.log.WithField("upstream response validation", err).Error()
+		couperErr.DefaultJSON.ServeError(couperErr.UpstreamResponseBufferingFailed).ServeHTTP(rw, req)
+		return
+	}
+	if responseValidationInput != nil {
+		if route != nil {
+			if err := openapi3filter.ValidateResponse(validationCtx, responseValidationInput); err != nil {
+				// TODO: use error template from parent endpoint>api>server
+				p.log.WithField("upstream response validation", err).Error()
+				couperErr.DefaultJSON.ServeError(couperErr.UpstreamResponseValidationFailed).ServeHTTP(rw, req)
+				return
+			}
+		} else {
+			p.log.Info("response validation enabled, but no route found")
+		}
+	}
+
 	// Deal with 101 Switching Protocols responses: (WebSocket, h2c, etc)
 	if res.StatusCode == http.StatusSwitchingProtocols {
 		p.setRoundtripContext(req, res)
@@ -242,11 +321,15 @@ func (p *Proxy) roundtrip(rw http.ResponseWriter, req *http.Request) {
 
 	rw.WriteHeader(res.StatusCode)
 
-	_, err = io.Copy(rw, res.Body)
-	if err != nil {
-		defer res.Body.Close()
-		roundtripInfo.Err = err
-		return
+	if body != nil {
+		rw.Write(body)
+	} else {
+		_, err = io.Copy(rw, res.Body)
+		if err != nil {
+			defer res.Body.Close()
+			roundtripInfo.Err = err
+			return
+		}
 	}
 
 	res.Body.Close() // close now, instead of defer, to populate res.Trailer