Add 'json_body' as config req variable

eval/context.go

@@ -3,8 +3,10 @@ package eval
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"io"
 	"io/ioutil"
+	"mime"
 	"net/http"
 	"net/url"
 	"os"
@@ -48,7 +50,7 @@ func NewENVContext(src []byte) *hcl.EvalContext {
 	}
 }
 
-func NewHTTPContext(baseCtx *hcl.EvalContext, req, bereq *http.Request, beresp *http.Response) *hcl.EvalContext {
+func NewHTTPContext(baseCtx *hcl.EvalContext, buffer bool, req, bereq *http.Request, beresp *http.Response) *hcl.EvalContext {
 	if req == nil {
 		return baseCtx
 	}
@@ -65,13 +67,21 @@ func NewHTTPContext(baseCtx *hcl.EvalContext, req, bereq *http.Request, beresp *
 		id = uid
 	}
 
+	if buffer {
+		switch req.Method {
+		case http.MethodPost, http.MethodPut, http.MethodPatch:
+			setGetBody(req)
+		}
+	}
+
 	evalCtx.Variables["req"] = cty.ObjectVal(reqCtxMap.Merge(ContextMap{
-		"id":     cty.StringVal(id),
-		"method": cty.StringVal(req.Method),
-		"path":   cty.StringVal(req.URL.Path),
-		"url":    cty.StringVal(newRawURL(req.URL).String()),
-		"query":  seetie.ValuesMapToValue(req.URL.Query()),
-		"post":   seetie.ValuesMapToValue(parseForm(req).PostForm),
+		"id":        cty.StringVal(id),
+		"method":    cty.StringVal(req.Method),
+		"path":      cty.StringVal(req.URL.Path),
+		"url":       cty.StringVal(newRawURL(req.URL).String()),
+		"query":     seetie.ValuesMapToValue(req.URL.Query()),
+		"post":      seetie.ValuesMapToValue(parseForm(req).PostForm),
+		"json_body": seetie.MapToValue(parseJSON(req)),
 	}.Merge(newVariable(httpCtx, req.Cookies(), req.Header))))
 
 	if beresp != nil {
@@ -105,33 +115,56 @@ func (rc readCloser) Close() error {
 	return rc.closer.Close()
 }
 
+func setGetBody(r *http.Request) *http.Request {
+	if r.Body != nil && r.GetBody == nil {
+		bodyBytes, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			panic(err)
+		}
+		r.GetBody = func() (io.ReadCloser, error) {
+			return newReadCloser(bytes.NewBuffer(bodyBytes), r.Body), nil
+		}
+		// reset
+		r.Body, _ = r.GetBody()
+	}
+	return r
+}
+
 // parseForm populates the request PostForm field.
 // As Proxy we should not consume the request body.
-// Create a copy, buffer and reset via GetBody method.
+// Rewind body via GetBody method.
 func parseForm(r *http.Request) *http.Request {
-	if r.Body == nil {
+	if r.GetBody == nil {
 		return r
 	}
-
 	switch r.Method {
 	case http.MethodPut, http.MethodPatch, http.MethodPost:
-		if r.GetBody == nil {
-			bodyBytes, err := ioutil.ReadAll(r.Body)
-			if err != nil {
-				panic(err)
-			}
-			r.GetBody = func() (io.ReadCloser, error) {
-				return newReadCloser(bytes.NewBuffer(bodyBytes), r.Body), nil
-			}
-		}
-
-		r.Body, _ = r.GetBody()
 		_ = r.ParseMultipartForm(defaultMaxMemory)
-		r.Body, _ = r.GetBody()
+		r.Body, _ = r.GetBody() // reset
 	}
 	return r
 }
 
+func parseJSON(r *http.Request) map[string]interface{} {
+	if r.GetBody == nil {
+		return nil
+	}
+
+	m, _, _ := mime.ParseMediaType(r.Header.Get("Content-Type"))
+	if m != "application/json" {
+		return nil
+	}
+
+	var result map[string]interface{}
+	b, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return nil
+	}
+	_ = json.Unmarshal(b, &result)
+	r.Body, _ = r.GetBody() // reset
+	return result
+}
+
 func newRawURL(u *url.URL) *url.URL {
 	rawURL := *u
 	rawURL.RawQuery = ""

eval/context_test.go

@@ -71,7 +71,7 @@ func TestNewHTTPContext(t *testing.T) {
 			bereq := req.Clone(context.Background())
 			beresp := newBeresp(bereq)
 
-			got := NewHTTPContext(tt.baseCtx, req, bereq, beresp)
+			got := NewHTTPContext(tt.baseCtx, true, req, bereq, beresp)
 			got.Functions = nil // we are not interested in a functions test
 
 			var hclResult EvalTestContext

handler/proxy.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"net/url"
 	"path"
+	"reflect"
 	"strconv"
 	"strings"
 	"time"
@@ -42,6 +43,7 @@ var (
 type Proxy struct {
 	evalContext *hcl.EvalContext
 	log         *logrus.Entry
+	mustBuffer  bool
 	options     *ProxyOptions
 	originURL   *url.URL
 	transport   *http.Transport
@@ -117,6 +119,7 @@ func NewProxy(options *ProxyOptions, log *logrus.Entry, evalCtx *hcl.EvalContext
 	proxy := &Proxy{
 		evalContext: evalCtx,
 		log:         log,
+		mustBuffer:  mustBuffer(options),
 		options:     options,
 		originURL:   originURL,
 		upstreamLog: logging.NewAccessLog(&logConf, log.Logger),
@@ -307,7 +310,7 @@ func (p *Proxy) setRoundtripContext(req *http.Request, beresp *http.Response) {
 		headerCtx = req.Header
 	}
 
-	evalCtx := eval.NewHTTPContext(p.evalContext, req, bereq, beresp)
+	evalCtx := eval.NewHTTPContext(p.evalContext, p.mustBuffer, req, bereq, beresp)
 
 	// Remove blacklisted headers after evaluation to be accessible within our context configuration.
 	if attrCtx == attrReqHeaders {
@@ -329,6 +332,32 @@ func (p *Proxy) setRoundtripContext(req *http.Request, beresp *http.Response) {
 	}
 }
 
+// mustBuffer determines if any of the hcl.bodies makes use of 'post' or 'json_body'.
+func mustBuffer(opts *ProxyOptions) bool {
+	for _, body := range opts.Context {
+		attrs, err := body.JustAttributes()
+		if err != nil {
+			return false
+		}
+		for _, attr := range attrs {
+			for _, traversal := range attr.Expr.Variables() {
+				if traversal.RootName() != "req" {
+					continue
+				}
+				for _, step := range traversal[1:] {
+					nameField := reflect.ValueOf(step).FieldByName("Name")
+					name := nameField.String()
+					switch name {
+					case "json_body", "post":
+						return true
+					}
+				}
+			}
+		}
+	}
+	return false
+}
+
 func isCorsRequest(req *http.Request) bool {
 	return req.Header.Get("Origin") != ""
 }