From 4c0d033311dd7668b558f349946237aeebf5d4e0 Mon Sep 17 00:00:00 2001
From: nrxr <nrxrco@gmail.com>
Date: Wed, 13 Nov 2019 21:26:30 -0400
Subject: [PATCH] net/url: add URL.Redacted() to return a password scrubbed
 string

Returning an URL.String() without the password is very useful for
situations where the URL is supposed to be logged and the password is
not useful to be shown.

This method re-uses URL.String() but with the password scrubbed and
substituted for a "xxxxx" in order to make it obvious that there was a
password. If the URL had no password then no "xxxxx" will be shown.

Fixes #34855
---
 src/net/url/url.go      | 10 +++++
 src/net/url/url_test.go | 89 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/src/net/url/url.go b/src/net/url/url.go
index 6480d4b432242b..7e4c29d95587f8 100644
--- a/src/net/url/url.go
+++ b/src/net/url/url.go
@@ -821,6 +821,16 @@ func (u *URL) String() string {
 	return buf.String()
 }
 
+// Redacted is like String but replaces any password with "xxxxx".
+// Only the password in u.URL is redacted.
+func (u *URL) Redacted() string {
+	ru := *u
+	if _, has := ru.User.Password(); has {
+		ru.User = UserPassword(ru.User.Username(), "xxxxx")
+	}
+	return ru.String()
+}
+
 // Values maps a string key to a list of values.
 // It is typically used for query parameters and form values.
 // Unlike in the http.Header map, the keys in a Values map
diff --git a/src/net/url/url_test.go b/src/net/url/url_test.go
index 79fd3d5c79f37f..081eddf697eb9c 100644
--- a/src/net/url/url_test.go
+++ b/src/net/url/url_test.go
@@ -765,6 +765,95 @@ func TestURLString(t *testing.T) {
 	}
 }
 
+var maskedURLTestsPtr = []struct {
+	url        *URL
+	want       string
+	shouldMask bool
+}{
+	{
+		url: &URL{
+			Scheme: "http",
+			Host:   "host.tld",
+			Path:   "this:that",
+			User:   UserPassword("user", "password"),
+		},
+		want:       "http://user:xxxxx@host.tld/this:that",
+		shouldMask: true,
+	},
+	{
+		url: &URL{
+			Scheme: "http",
+			Host:   "host.tld",
+			Path:   "this:that",
+			User:   User("user"),
+		},
+		want:       "http://user@host.tld/this:that",
+		shouldMask: false,
+	},
+}
+
+func TestURLRedacted(t *testing.T) {
+	cases := []struct {
+		name string
+		url  *URL
+		want string
+	}{
+		{
+			name: "non-blank Password",
+			url: &URL{
+				Scheme: "http",
+				Host:   "host.tld",
+				Path:   "this:that",
+				User:   UserPassword("user", "password"),
+			},
+			want: "http://user:xxxxx@host.tld/this:that",
+		},
+		{
+			name: "blank Password",
+			url: &URL{
+				Scheme: "http",
+				Host:   "host.tld",
+				Path:   "this:that",
+				User:   User("user"),
+			},
+			want: "http://user@host.tld/this:that",
+		},
+		{
+			name: "nil User",
+			url: &URL{
+				Scheme: "http",
+				Host:   "host.tld",
+				Path:   "this:that",
+				User:   UserPassword("", "password"),
+			},
+			want: "http://:xxxxx@host.tld/this:that",
+		},
+		{
+			name: "blank Username, blank Password",
+			url: &URL{
+				Scheme: "http",
+				Host:   "host.tld",
+				Path:   "this:that",
+			},
+			want: "http://host.tld/this:that",
+		},
+		{
+			name: "empty URL",
+			url:  &URL{},
+			want: "",
+		},
+	}
+
+	for _, tt := range cases {
+		t := t
+		t.Run(tt.name, func(t *testing.T) {
+			if g, w := tt.url.Redacted(), tt.want; g != w {
+				t.Fatalf("got: %q\nwant: %q", g, w)
+			}
+		})
+	}
+}
+
 type EscapeTest struct {
 	in  string
 	out string