fix(notify): quote libpq connection parameters

The discrete PostgreSQL connection path concatenated raw values into a libpq keyword/value string. Whitespace, quotes, or backslashes could split a value into additional parameters or make an otherwise valid configuration fail to parse; the path also used the unsupported keyword username instead of user.

Render every generated value as a single-quoted libpq parameter, escape quotes and backslashes, and use the correct user key. Keep the existing connection_string form untouched. The earlier attempt to register migrated PostgreSQL and MySQL fields is deliberately absent because those key names collide with the legacy connection-string tokenizer.

Focused tests cover ordinary values, whitespace, quotes, backslashes, and parameter-shaped input.

Co-authored-by: ChatGPT <noreply@openai.com>
Co-authored-by: Claude <noreply@anthropic.com>

internal/event/target/postgresql.go

@@ -403,25 +403,41 @@ func (target *PostgreSQLTarget) initPostgreSQL() error {
 	return nil
 }
 
+// quoteConnParam renders a value for a libpq keyword/value connection string.
+// Parameters are separated by whitespace, so an unquoted value containing a
+// space is read as the start of the next keyword and the connection fails on a
+// string the operator never wrote. Single quotes make the value opaque;
+// backslash and the quote itself are the only characters that need escaping
+// inside them.
+//
+// Quoting unconditionally rather than only when required keeps the two cases
+// from diverging: libpq treats 'localhost' and localhost identically, so there
+// is nothing to gain by deciding per value which form to emit.
+func quoteConnParam(v string) string {
+	return "'" + strings.NewReplacer(`\`, `\\`, `'`, `\'`).Replace(v) + "'"
+}
+
 // NewPostgreSQLTarget - creates new PostgreSQL target.
 func NewPostgreSQLTarget(id string, args PostgreSQLArgs, loggerOnce logger.LogOnce) (*PostgreSQLTarget, error) {
 	params := []string{args.ConnectionString}
 	if args.ConnectionString == "" {
 		params = []string{}
 		if !args.Host.IsEmpty() {
-			params = append(params, "host="+args.Host.String())
+			params = append(params, "host="+quoteConnParam(args.Host.String()))
 		}
 		if args.Port != "" {
-			params = append(params, "port="+args.Port)
+			params = append(params, "port="+quoteConnParam(args.Port))
 		}
 		if args.Username != "" {
-			params = append(params, "username="+args.Username)
+			// libpq's keyword is "user"; "username" is rejected by the server
+			// as an unrecognized configuration parameter.
+			params = append(params, "user="+quoteConnParam(args.Username))
 		}
 		if args.Password != "" {
-			params = append(params, "password="+args.Password)
+			params = append(params, "password="+quoteConnParam(args.Password))
 		}
 		if args.Database != "" {
-			params = append(params, "dbname="+args.Database)
+			params = append(params, "dbname="+quoteConnParam(args.Database))
 		}
 	}
 	connStr := strings.Join(params, " ")

internal/event/target/postgresql_test.go

@@ -50,3 +50,25 @@ func TestPsqlTableNameValidation(t *testing.T) {
 		}
 	}
 }
+
+func TestQuoteConnParam(t *testing.T) {
+	testCases := []struct {
+		value    string
+		expected string
+	}{
+		{"localhost", "'localhost'"},
+		{"5432", "'5432'"},
+		// The reason this function exists: parameters are whitespace
+		// separated, so an unquoted space starts a new keyword.
+		{"pass word", "'pass word'"},
+		{"it's", `'it\'s'`},
+		{`back\slash`, `'back\\slash'`},
+		{`'; host=evil.example.com; x='`, `'\'; host=evil.example.com; x=\''`},
+		{"", "''"},
+	}
+	for _, testCase := range testCases {
+		if got := quoteConnParam(testCase.value); got != testCase.expected {
+			t.Errorf("quoteConnParam(%q) = %s, expected %s", testCase.value, got, testCase.expected)
+		}
+	}
+}