🐛 fix: refactor response body handling in multiple relay handlers to utilize IOCopyBytesGracefully

common/http.go

@@ -3,9 +3,10 @@ package common
 import (
 	"bytes"
 	"fmt"
-	"github.com/gin-gonic/gin"
 	"io"
 	"net/http"
+
+	"github.com/gin-gonic/gin"
 )
 
 func CloseResponseBodyGracefully(httpResponse *http.Response) {
@@ -19,37 +20,37 @@ func CloseResponseBodyGracefully(httpResponse *http.Response) {
 }
 
 func IOCopyBytesGracefully(c *gin.Context, src *http.Response, data []byte) {
-	if src == nil || src.Body == nil {
-		return
-	}
-
-	defer CloseResponseBodyGracefully(src)
-
 	if c.Writer == nil {
 		return
 	}
 
-	src.Body = io.NopCloser(bytes.NewBuffer(data))
+	body := io.NopCloser(bytes.NewBuffer(data))
 
 	// We shouldn't set the header before we parse the response body, because the parse part may fail.
 	// And then we will have to send an error response, but in this case, the header has already been set.
 	// So the httpClient will be confused by the response.
 	// For example, Postman will report error, and we cannot check the response at all.
-	for k, v := range src.Header {
-		// avoid setting Content-Length
-		if k == "Content-Length" {
-			continue
+	if src != nil {
+		for k, v := range src.Header {
+			// avoid setting Content-Length
+			if k == "Content-Length" {
+				continue
+			}
+			c.Writer.Header().Set(k, v[0])
 		}
-		c.Writer.Header().Set(k, v[0])
 	}
 
-	// set Content-Length header manually
+	// set Content-Length header manually BEFORE calling WriteHeader
 	c.Writer.Header().Set("Content-Length", fmt.Sprintf("%d", len(data)))
 
-	c.Writer.WriteHeader(src.StatusCode)
-	c.Writer.WriteHeaderNow()
+	// Write header with status code (this sends the headers)
+	if src != nil {
+		c.Writer.WriteHeader(src.StatusCode)
+	} else {
+		c.Writer.WriteHeader(http.StatusOK)
+	}
 
-	_, err := io.Copy(c.Writer, src.Body)
+	_, err := io.Copy(c.Writer, body)
 	if err != nil {
 		LogError(c, fmt.Sprintf("failed to copy response body: %s", err.Error()))
 	}