From b4fe1dffb478c86f72932e364c61419301ba897c Mon Sep 17 00:00:00 2001
From: Dwi Siswanto <git@dw1.io>
Date: Thu, 12 Dec 2024 11:39:36 +0700
Subject: [PATCH] fix(httpclientpool): rebuild malformed Location URL

Signed-off-by: Dwi Siswanto <git@dw1.io>
---
 .../http/httpclientpool/clientpool.go         | 28 ++++++++++++++++++-
 pkg/protocols/http/httpclientpool/errors.go   |  7 +++++
 2 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 pkg/protocols/http/httpclientpool/errors.go

diff --git a/pkg/protocols/http/httpclientpool/clientpool.go b/pkg/protocols/http/httpclientpool/clientpool.go
index 94ed61ff3f..7f9eeed140 100644
--- a/pkg/protocols/http/httpclientpool/clientpool.go
+++ b/pkg/protocols/http/httpclientpool/clientpool.go
@@ -3,6 +3,7 @@ package httpclientpool
 import (
 	"context"
 	"crypto/tls"
+	"fmt"
 	"net"
 	"net/http"
 	"net/http/cookiejar"
@@ -25,6 +26,7 @@ import (
 	"github.com/projectdiscovery/rawhttp"
 	"github.com/projectdiscovery/retryablehttp-go"
 	mapsutil "github.com/projectdiscovery/utils/maps"
+	urlutil "github.com/projectdiscovery/utils/url"
 )
 
 var (
@@ -377,7 +379,7 @@ func makeCheckRedirectFunc(redirectType RedirectFlow, maxRedirects int) checkRed
 	}
 }
 
-func checkMaxRedirects(_ *http.Request, via []*http.Request, maxRedirects int) error {
+func checkMaxRedirects(req *http.Request, via []*http.Request, maxRedirects int) error {
 	if maxRedirects == 0 {
 		if len(via) > defaultMaxRedirects {
 			return http.ErrUseLastResponse
@@ -388,5 +390,29 @@ func checkMaxRedirects(_ *http.Request, via []*http.Request, maxRedirects int) e
 	if len(via) > maxRedirects {
 		return http.ErrUseLastResponse
 	}
+
+	// NOTE(dwisiswant0): rebuild request URL. See #5900.
+	if u := req.URL.String(); !isURLEncoded(u) {
+		parsed, err := urlutil.Parse(u)
+		if err != nil {
+			return fmt.Errorf("%w: %w", ErrRebuildURL, err)
+		}
+
+		req.URL = parsed.URL
+	}
+
 	return nil
 }
+
+// isURLEncoded is an helper function to check if the URL is already encoded
+//
+// NOTE(dwisiswant0): shall we move this under `projectdiscovery/utils/urlutil`?
+func isURLEncoded(s string) bool {
+	decoded, err := url.QueryUnescape(s)
+	if err != nil {
+		// If decoding fails, it may indicate a malformed URL/invalid encoding.
+		return false
+	}
+
+	return decoded != s
+}
diff --git a/pkg/protocols/http/httpclientpool/errors.go b/pkg/protocols/http/httpclientpool/errors.go
new file mode 100644
index 0000000000..e5c915f93e
--- /dev/null
+++ b/pkg/protocols/http/httpclientpool/errors.go
@@ -0,0 +1,7 @@
+package httpclientpool
+
+import "errors"
+
+var (
+	ErrRebuildURL = errors.New("could not rebuild request URL")
+)