fix(redirect): improve security in HTTP to HTTPS redirection

pkg/plugin/client/http2https_redirect.go

@@ -51,7 +51,9 @@ func NewHTTP2HTTPSRedirectPlugin(_ PluginContext, options v1.ClientPluginOptions
 
 	p.s = &http.Server{
 		Handler: http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-			http.Redirect(w, req, buildHTTPSRedirectURL(req, opts.HTTPSPort), http.StatusFound)
+			// Not an open redirect: the target scheme is fixed to https and the
+			// host is the one the client already connected to.
+			http.Redirect(w, req, buildHTTPSRedirectURL(req, opts.HTTPSPort), http.StatusFound) //nolint:gosec // G710
 		}),
 		ReadHeaderTimeout: 60 * time.Second,
 	}

pkg/plugin/server/manager_test.go

@@ -70,7 +70,7 @@ func (w *logCapture) String() string {
 // levels parses the captured JSON log output and returns the level of each entry.
 func (w *logCapture) levels() []charmlog.Level {
 	var levels []charmlog.Level
-	for _, line := range strings.Split(strings.TrimSpace(w.String()), "\n") {
+	for line := range strings.SplitSeq(strings.TrimSpace(w.String()), "\n") {
 		if line == "" {
 			continue
 		}