Try to extract request body payload when the GetBody func is nil

instrumentation/nethttp/client.go

@@ -222,43 +222,73 @@ func (t *Transport) doRoundTrip(req *http.Request) (*http.Response, error) {
 
 // Gets the request payload
 func getRequestPayload(req *http.Request, bufferSize int) string {
-	var rqPayload string
-	if req != nil && req.Body != nil && req.Body != http.NoBody && req.GetBody != nil {
-		rqBody, rqErr := req.GetBody()
-		if rqErr == nil {
-			rqBodyBuffer := make([]byte, bufferSize)
-			if len, err := rqBody.Read(rqBodyBuffer); err == nil && len > 0 {
-				if len < bufferSize {
-					rqBodyBuffer = rqBodyBuffer[:len]
-				}
-				rqRunes := bytes.Runes(rqBodyBuffer)
-				rqPayload = string(rqRunes)
-			}
+	if req == nil || req.Body == nil || req.Body == http.NoBody {
+		return ""
+	}
+	if req.GetBody == nil {
+		// GetBody is nil in server requests
+		nBody, payload := getBodyPayload(req.Body, bufferSize)
+		req.Body = nBody
+		return payload
+	}
+	rqBody, rqErr := req.GetBody()
+	if rqErr != nil {
+		return ""
+	}
+	rqBodyBuffer := make([]byte, bufferSize)
+	if ln, err := rqBody.Read(rqBodyBuffer); err == nil && ln > 0 {
+		if ln < bufferSize {
+			rqBodyBuffer = rqBodyBuffer[:ln]
 		}
+		return string(bytes.Runes(rqBodyBuffer))
 	}
-	return rqPayload
+	return ""
+}
+
+// Gets the payload from a body
+func getBodyPayload(body io.ReadCloser, bufferSize int) (io.ReadCloser, string) {
+	if body == nil {
+		return body, ""
+	}
+	rsBodyBuffer := make([]byte, bufferSize)
+	ln, _ := body.Read(rsBodyBuffer)
+	if ln == 0 {
+		return body, ""
+	}
+	if ln < bufferSize {
+		rsBodyBuffer = rsBodyBuffer[:ln]
+	}
+	rsPayload := string(bytes.Runes(rsBodyBuffer))
+	rBody := struct {
+		io.Reader
+		io.Closer
+	}{
+		io.MultiReader(bytes.NewReader(rsBodyBuffer), body),
+		body,
+	}
+	return rBody, rsPayload
 }
 
 // Gets the response payload
 func getResponsePayload(resp *http.Response, bufferSize int) string {
-	var rsPayload string
-	if resp != nil && resp.Body != nil && resp.Body != http.NoBody {
-		rsBodyBuffer := make([]byte, bufferSize)
-		len, _ := resp.Body.Read(rsBodyBuffer)
-		if len > 0 {
-			if len < bufferSize {
-				rsBodyBuffer = rsBodyBuffer[:len]
-			}
-			rsRunes := bytes.Runes(rsBodyBuffer)
-			rsPayload = string(rsRunes)
-			resp.Body = struct {
-				io.Reader
-				io.Closer
-			}{
-				io.MultiReader(bytes.NewReader(rsBodyBuffer), resp.Body),
-				resp.Body,
-			}
-		}
+	if resp == nil || resp.Body == nil || resp.Body == http.NoBody {
+		return ""
+	}
+	rsBodyBuffer := make([]byte, bufferSize)
+	ln, _ := resp.Body.Read(rsBodyBuffer)
+	if ln == 0 {
+		return ""
+	}
+	if ln < bufferSize {
+		rsBodyBuffer = rsBodyBuffer[:ln]
+	}
+	rsPayload := string(bytes.Runes(rsBodyBuffer))
+	resp.Body = struct {
+		io.Reader
+		io.Closer
+	}{
+		io.MultiReader(bytes.NewReader(rsBodyBuffer), resp.Body),
+		resp.Body,
 	}
 	return rsPayload
 }

instrumentation/nethttp/nethttp_test.go

@@ -1,6 +1,7 @@
 package nethttp
 
 import (
+	"bytes"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -15,7 +16,7 @@ import (
 var r *tracer.InMemorySpanRecorder
 
 func TestMain(m *testing.M) {
-	PatchHttpDefaultClient()
+	PatchHttpDefaultClient(WithPayloadInstrumentation())
 
 	// Test tracer
 	r = tracer.NewInMemoryRecorder()
@@ -64,10 +65,10 @@ func TestHttpServer(t *testing.T) {
 			return
 		}
 	})
-	server := httptest.NewServer(Middleware(nil))
+	server := httptest.NewServer(Middleware(nil, MWPayloadInstrumentation()))
 
 	url := fmt.Sprintf("%s/hello", server.URL)
-	req, err := http.NewRequest("GET", url, nil)
+	req, err := http.NewRequest("POST", url, bytes.NewReader([]byte("Hello world request")))
 	if err != nil {
 		t.Fatalf("%+v", err)
 	}
@@ -87,18 +88,22 @@ func TestHttpServer(t *testing.T) {
 		t.Fatalf("there aren't the right number of spans: %d", len(spans))
 	}
 	checkTags(t, spans[0].Tags, map[string]string{
-		"component":        "net/http",
-		"http.method":      "GET",
-		"http.url":         "/hello",
-		"span.kind":        "server",
-		"http.status_code": "200",
+		"component":             "net/http",
+		"http.method":           "POST",
+		"http.url":              "/hello",
+		"span.kind":             "server",
+		"http.status_code":      "200",
+		"http.request_payload":  "Hello world request",
+		"http.response_payload": "Hello world",
 	})
 	checkTags(t, spans[1].Tags, map[string]string{
-		"component":   "net/http",
-		"http.method": "GET",
-		"http.url":    url,
-		"peer.ipv4":   "127.0.0.1",
-		"span.kind":   "client",
+		"component":             "net/http",
+		"http.method":           "POST",
+		"http.url":              url,
+		"peer.ipv4":             "127.0.0.1",
+		"span.kind":             "client",
+		"http.request_payload":  "Hello world request",
+		"http.response_payload": "Hello world",
 	})
 }