Add escape logic for header (gin-gonic#3500)

gin.go

@@ -9,6 +9,7 @@ import (
 	"html/template"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"path"
 	"strings"
@@ -668,6 +669,9 @@ func redirectTrailingSlash(c *Context) {
 	req := c.Request
 	p := req.URL.Path
 	if prefix := path.Clean(c.Request.Header.Get("X-Forwarded-Prefix")); prefix != "." {
+		prefix = url.QueryEscape(prefix)
+		prefix = strings.ReplaceAll(prefix, "%2F", "/")
+
 		p = prefix + "/" + req.URL.Path
 	}
 	req.URL.Path = p + "/"

routes_test.go

@@ -185,6 +185,18 @@ func TestRouteRedirectTrailingSlash(t *testing.T) {
 	w = PerformRequest(router, http.MethodGet, "/path2/", header{Key: "X-Forwarded-Prefix", Value: "/api/"})
 	assert.Equal(t, 200, w.Code)
 
+	w = PerformRequest(router, http.MethodGet, "/path/", header{Key: "X-Forwarded-Prefix", Value: "../../bug#?"})
+	assert.Equal(t, "../../../bug%2523%253F/path", w.Header().Get("Location"))
+	assert.Equal(t, 301, w.Code)
+
+	w = PerformRequest(router, http.MethodGet, "/path/", header{Key: "X-Forwarded-Prefix", Value: "https://gin-gonic.com/#"})
+	assert.Equal(t, "https%3A/gin-gonic.com/%23/https%253A/gin-gonic.com/%2523/path", w.Header().Get("Location"))
+	assert.Equal(t, 301, w.Code)
+
+	w = PerformRequest(router, http.MethodGet, "/path/", header{Key: "X-Forwarded-Prefix", Value: "#bug"})
+	assert.Equal(t, "%23bug/%2523bug/path", w.Header().Get("Location"))
+	assert.Equal(t, 301, w.Code)
+
 	router.RedirectTrailingSlash = false
 
 	w = PerformRequest(router, http.MethodGet, "/path/")