HTTP Transport - get global tracer each time, fix request data (#69)

* get global tracer each time

* read request data before sending

wrappers/net/http/client.go

@@ -95,10 +95,12 @@ func NewWrappedTracingTransport(rt http.RoundTripper, args ...context.Context) *
 
 // RoundTrip implements the RoundTripper interface to trace HTTP calls
 func (t *TracingTransport) RoundTrip(req *http.Request) (resp *http.Response, err error) {
+	// reference to the tracer
+	tr := t.tracer
 	// if the TracingTransport is created before the global tracer is created it will be nil
-	if t.tracer == nil {
-		t.tracer = internal.ExtractTracer(nil)
-		if t.tracer != nil && t.tracer.GetConfig().Debug {
+	if tr == nil {
+		tr = internal.ExtractTracer(nil)
+		if tr != nil && tr.GetConfig().Debug {
 			log.Println("EPSAGON DEBUG: defaulting to global tracer in RoundTrip")
 		}
 	}
@@ -111,33 +113,61 @@ func (t *TracingTransport) RoundTrip(req *http.Request) (resp *http.Response, er
 	}()
 	defer epsagon.GeneralEpsagonRecover("net.http.RoundTripper", "RoundTrip", t.tracer)
 	startTime := tracer.GetTimestamp()
+	reqHeaders, reqBody := t.extractRequestData(req, tr)
 	if !isBlacklistedURL(req.URL) {
 		req.Header[EPSAGON_TRACEID_HEADER_KEY] = []string{generateEpsagonTraceID()}
 	}
 
 	resp, err = t.transport.RoundTrip(req)
 
 	called = true
-	event := postSuperCall(startTime, req.URL.String(), req.Method, resp, err, t.getMetadataOnly())
-	t.addDataToEvent(req, resp, event)
-	t.tracer.AddEvent(event)
+	event := postSuperCall(startTime, req.URL.String(), req.Method, resp, err, t.getMetadataOnly(tr))
+	t.addDataToEvent(reqHeaders, reqBody, req, event, tr)
+	tr.AddEvent(event)
 	return
 
 }
 
-func (t *TracingTransport) getMetadataOnly() bool {
-	return t.MetadataOnly || t.tracer.GetConfig().MetadataOnly
+func (t *TracingTransport) getMetadataOnly(tr tracer.Tracer) bool {
+	return t.MetadataOnly || tr.GetConfig().MetadataOnly
 }
 
-func (t *TracingTransport) addDataToEvent(req *http.Request, resp *http.Response, event *protocol.Event) {
+func (t *TracingTransport) addDataToEvent(reqHeaders, reqBody string, req *http.Request, event *protocol.Event, tr tracer.Tracer) {
 	if req != nil {
 		addTraceIdToEvent(req, event)
 	}
-	if resp != nil {
-		if !t.getMetadataOnly() {
-			updateRequestData(resp.Request, event.Resource.Metadata)
-		}
+	if !t.getMetadataOnly(tr) {
+		event.Resource.Metadata["request_headers"] = reqHeaders
+		event.Resource.Metadata["request_body"] = reqBody
+	}
+}
+
+func (t *TracingTransport) extractRequestData(req *http.Request, tr tracer.Tracer) (headers string, body string) {
+	if t.getMetadataOnly(tr) {
+		return
+	}
+
+	headers, err := formatHeaders(req.Header)
+	if err != nil {
+		headers = ""
 	}
+
+	if req.Body == nil {
+		return
+	}
+
+	buf, err := ioutil.ReadAll(req.Body)
+	if err != nil {
+		return
+	}
+	req.Body = ioutil.NopCloser(bytes.NewReader(buf))
+	// truncates request body to the first 64KB
+	trimmed := buf
+	if len(buf) > MAX_METADATA_SIZE {
+		trimmed = buf[0:MAX_METADATA_SIZE]
+	}
+	body = string(trimmed)
+	return
 }
 
 func isBlacklistedURL(parsedUrl *url.URL) bool {