Ensure loggableDSN scrubs passwords in different ways

The previous implementation of the function was only scrubbing those passwords
that were part of a basic http authentication method, which means it
expected passwords to be provided as part of the URL.

However, the password
may also be specified as a parameter, or when using key-values, it may be
specified as a password=value string.

This commit ensures those passwords will also not be retained, but
removed.

Signed-off-by: Feike Steenbergen <[email protected]>

Author: feikesteenbergen

Diff for: cmd/postgres_exporter/util.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"math"
 	"net/url"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -212,10 +213,24 @@ func loggableDSN(dsn string) string {
 	if err != nil {
 		return "could not parse DATA_SOURCE_NAME"
 	}
+
+	// If the DSN is not a URL it is expected to be in the `key1=value1 key2=value2` format
+	if pDSN.Scheme == "" {
+		re := regexp.MustCompile(`(\s?password=([^"\s]+|"[^"]+"))`)
+		stripped := re.ReplaceAllString(dsn, " password=PASSWORD_REMOVED")
+		return strings.TrimSpace(stripped)
+	}
+
 	// Blank user info if not nil
 	if pDSN.User != nil {
 		pDSN.User = url.UserPassword(pDSN.User.Username(), "PASSWORD_REMOVED")
 	}
 
+	// If the password is contained in a URL parameter, we should remove it there
+	if q, err := url.ParseQuery(pDSN.RawQuery); err == nil && q.Has("password") {
+		q.Set("password", "PASSWORD_REMOVED")
+		pDSN.RawQuery = q.Encode()
+	}
+
 	return pDSN.String()
 }

Diff for: cmd/postgres_exporter/util_test.go

@@ -0,0 +1,73 @@
+// Copyright 2021 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	. "gopkg.in/check.v1"
+)
+
+func (s *FunctionalSuite) TestLoggableDSN(c *C) {
+	type TestCase struct {
+		input    string
+		expected string
+	}
+
+	cases := []TestCase{
+		{
+			input:    "host=host.example.com user=postgres port=5432 password=s3cr3t",
+			expected: "host=host.example.com user=postgres port=5432 password=PASSWORD_REMOVED",
+		},
+
+		{
+			input:    "host=host.example.com user=postgres port=5432 password=\"s3cr 3t\"",
+			expected: "host=host.example.com user=postgres port=5432 password=PASSWORD_REMOVED",
+		},
+
+		{
+			input:    "password=abcde host=host.example.com user=postgres port=5432",
+			expected: "password=PASSWORD_REMOVED host=host.example.com user=postgres port=5432",
+		},
+
+		{
+			input:    "password=abcde host=host.example.com user=postgres port=5432 password=\"s3cr 3t\"",
+			expected: "password=PASSWORD_REMOVED host=host.example.com user=postgres port=5432 password=PASSWORD_REMOVED",
+		},
+
+		{
+			input:    "postgresql://host.example.com:5432/tsdb?user=postgres",
+			expected: "postgresql://host.example.com:5432/tsdb?user=postgres",
+		},
+
+		{
+			input:    "postgresql://user:[email protected]:5432/tsdb?user=postgres",
+			expected: "postgresql://user:[email protected]:5432/tsdb?user=postgres",
+		},
+
+		{
+			input:    "postgresql://host.example.com:5432/tsdb?user=postgres&password=s3cr3t",
+			expected: "postgresql://host.example.com:5432/tsdb?password=PASSWORD_REMOVED&user=postgres",
+		},
+
+		{
+			input:    "host=host.example.com user=postgres port=5432",
+			expected: "host=host.example.com user=postgres port=5432",
+		},
+	}
+
+	for _, cs := range cases {
+		loggable := loggableDSN(cs.input)
+		c.Assert(loggable, Equals, cs.expected)
+	}
+
+}