From 7a77463ec96db273ac071ec092ab44b9e5e2b25a Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Sun, 30 Dec 2018 16:53:57 -0600
Subject: [PATCH] Restructure connect process

- Moved lots of connection logic to pgconn from pgx
- Extracted pgpassfile package
---
 pgpass.go      | 109 +++++++++++++++++++++++++++++++++++++++++++++++++
 pgpass_test.go |  52 +++++++++++++++++++++++
 2 files changed, 161 insertions(+)
 create mode 100644 pgpass.go
 create mode 100644 pgpass_test.go

diff --git a/pgpass.go b/pgpass.go
new file mode 100644
index 0000000..cd249bd
--- /dev/null
+++ b/pgpass.go
@@ -0,0 +1,109 @@
+package pgpassfile
+
+import (
+	"bufio"
+	"io"
+	"os"
+	"regexp"
+	"strings"
+)
+
+// Entry represents a line in a PG passfile.
+type Entry struct {
+	Hostname string
+	Port     string
+	Database string
+	Username string
+	Password string
+}
+
+// Passfile is the in memory data structure representing a PG passfile.
+type Passfile struct {
+	Entries []*Entry
+}
+
+// ReadPassfile reads the file at path and parses it into a Passfile.
+func ReadPassfile(path string) (*Passfile, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	return ParsePassfile(f)
+}
+
+// ParsePassfile reads r and parses it into a Passfile.
+func ParsePassfile(r io.Reader) (*Passfile, error) {
+	passfile := &Passfile{}
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		entry := parseLine(scanner.Text())
+		if entry != nil {
+			passfile.Entries = append(passfile.Entries, entry)
+		}
+	}
+
+	return passfile, scanner.Err()
+}
+
+// Match (not colons or escaped colon or escaped backslash)+. Essentially gives a split on unescaped
+// colon.
+var colonSplitterRegexp = regexp.MustCompile("(([^:]|(\\:)))+")
+
+// var colonSplitterRegexp = regexp.MustCompile("((?:[^:]|(?:\\:)|(?:\\\\))+)")
+
+// parseLine parses a line into an *Entry. It returns nil on comment lines or any other unparsable
+// line.
+func parseLine(line string) *Entry {
+	const (
+		tmpBackslash = "\r"
+		tmpColon     = "\n"
+	)
+
+	line = strings.TrimSpace(line)
+
+	if strings.HasPrefix(line, "#") {
+		return nil
+	}
+
+	line = strings.Replace(line, `\\`, tmpBackslash, -1)
+	line = strings.Replace(line, `\:`, tmpColon, -1)
+
+	parts := strings.Split(line, ":")
+	if len(parts) != 5 {
+		return nil
+	}
+
+	// Unescape escaped colons and backslashes
+	for i := range parts {
+		parts[i] = strings.Replace(parts[i], tmpBackslash, `\`, -1)
+		parts[i] = strings.Replace(parts[i], tmpColon, `:`, -1)
+	}
+
+	return &Entry{
+		Hostname: parts[0],
+		Port:     parts[1],
+		Database: parts[2],
+		Username: parts[3],
+		Password: parts[4],
+	}
+}
+
+// FindPassword finds the password for the provided hostname, port, database, and username. For a
+// Unix domain socket hostname must be set to "localhost". An empty string will be returned if no
+// match is found.
+//
+// See https://www.postgresql.org/docs/current/libpq-pgpass.html for more password file information.
+func (pf *Passfile) FindPassword(hostname, port, database, username string) (password string) {
+	for _, e := range pf.Entries {
+		if (e.Hostname == "*" || e.Hostname == hostname) &&
+			(e.Port == "*" || e.Port == port) &&
+			(e.Database == "*" || e.Database == database) &&
+			(e.Username == "*" || e.Username == username) {
+			return e.Password
+		}
+	}
+	return ""
+}
diff --git a/pgpass_test.go b/pgpass_test.go
new file mode 100644
index 0000000..adf7f2a
--- /dev/null
+++ b/pgpass_test.go
@@ -0,0 +1,52 @@
+package pgpassfile
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func unescape(s string) string {
+	s = strings.Replace(s, `\:`, `:`, -1)
+	s = strings.Replace(s, `\\`, `\`, -1)
+	return s
+}
+
+var passfile = [][]string{
+	{"test1", "5432", "larrydb", "larry", "whatstheidea"},
+	{"test1", "5432", "moedb", "moe", "imbecile"},
+	{"test1", "5432", "curlydb", "curly", "nyuknyuknyuk"},
+	{"test2", "5432", "*", "shemp", "heymoe"},
+	{"test2", "5432", "*", "*", `test\\ing\:`},
+	{"localhost", "*", "*", "*", "sesam"},
+	{"test3", "*", "", "", "swordfish"}, // user will be filled later
+}
+
+func TestParsePassFile(t *testing.T) {
+	buf := bytes.NewBufferString(`# A comment
+	test1:5432:larrydb:larry:whatstheidea
+	test1:5432:moedb:moe:imbecile
+	test1:5432:curlydb:curly:nyuknyuknyuk
+	test2:5432:*:shemp:heymoe
+	test2:5432:*:*:test\\ing\:
+	localhost:*:*:*:sesam
+		`)
+
+	passfile, err := ParsePassfile(buf)
+	require.Nil(t, err)
+
+	assert.Len(t, passfile.Entries, 6)
+
+	assert.Equal(t, "whatstheidea", passfile.FindPassword("test1", "5432", "larrydb", "larry"))
+	assert.Equal(t, "imbecile", passfile.FindPassword("test1", "5432", "moedb", "moe"))
+	assert.Equal(t, `test\ing:`, passfile.FindPassword("test2", "5432", "something", "else"))
+	assert.Equal(t, "sesam", passfile.FindPassword("localhost", "9999", "foo", "bare"))
+
+	assert.Equal(t, "", passfile.FindPassword("wrong", "5432", "larrydb", "larry"))
+	assert.Equal(t, "", passfile.FindPassword("test1", "wrong", "larrydb", "larry"))
+	assert.Equal(t, "", passfile.FindPassword("test1", "5432", "wrong", "larry"))
+	assert.Equal(t, "", passfile.FindPassword("test1", "5432", "larrydb", "wrong"))
+}