Refine redirect guardrails

Author: gaby

client/transport.go

@@ -271,10 +271,11 @@ type redirectClient interface {
 func doRedirectsWithClient(req *fasthttp.Request, resp *fasthttp.Response, maxRedirects int, client redirectClient) error {
 	currentURL := req.URI().String()
 	redirects := 0
-	originalLimit := maxRedirects
+	singleRequestOnly := maxRedirects <= 0
 
 	if maxRedirects < 0 {
 		maxRedirects = defaultRedirectLimit
+		singleRequestOnly = false
 	}
 
 	for {
@@ -289,7 +290,7 @@ func doRedirectsWithClient(req *fasthttp.Request, resp *fasthttp.Response, maxRe
 			return nil
 		}
 
-		if originalLimit == 0 {
+		if singleRequestOnly {
 			return nil
 		}
 
@@ -312,6 +313,7 @@ func doRedirectsWithClient(req *fasthttp.Request, resp *fasthttp.Response, maxRe
 		if req.Header.IsPost() && (statusCode == fasthttp.StatusMovedPermanently || statusCode == fasthttp.StatusFound) {
 			req.Header.SetMethod(fasthttp.MethodGet)
 			req.SetBody(nil)
+			req.Header.Del(fasthttp.HeaderContentType)
 		}
 	}
 }

client/transport_test.go

@@ -299,13 +299,15 @@ func TestDoRedirectsWithClientBranches(t *testing.T) {
 
 	req.SetRequestURI("http://example.com/start")
 	req.Header.SetMethod(fasthttp.MethodPost)
+	req.Header.SetContentType("application/json")
 	req.SetBodyString("payload")
 
 	client := &stubRedirectClient{calls: []stubRedirectCall{{status: ptrInt(fasthttp.StatusMovedPermanently), location: ptrString("/redirect")}, {status: ptrInt(fasthttp.StatusOK)}}}
 	require.NoError(t, doRedirectsWithClient(req, resp, -1, client))
 	require.Equal(t, fasthttp.MethodGet, string(req.Header.Method()))
 	require.Equal(t, "http://example.com/redirect", req.URI().String())
 	require.Empty(t, req.Body())
+	require.Len(t, req.Header.ContentType(), 0)
 
 	resp.Reset()
 	req.Header.SetMethod(fasthttp.MethodPost)
@@ -319,6 +321,7 @@ func TestDoRedirectsWithClientBranches(t *testing.T) {
 	require.Equal(t, "http://example.com/again", req.URI().String())
 	require.Equal(t, "payload", string(req.Body()))
 	require.Equal(t, 1, singleCall.CallCount())
+	require.Equal(t, fasthttp.StatusFound, resp.Header.StatusCode())
 
 	resp.Reset()
 	req.Header.SetMethod(fasthttp.MethodPost)