allow non-standards fallback for all http.TimeFormats (#15662)

fixes #15645

internal/amztime/parse.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2015-2022 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// Package amztime implements AWS specific time parsing and deviations
+package amztime
+
+import (
+	"errors"
+	"net/http"
+	"time"
+)
+
+// Supported amz date formats.
+var amzDateFormats = []string{
+	// Do not change this order, x-amz-date format is usually in
+	// iso8601Format rest are meant for relaxed handling of other
+	// odd SDKs that might be out there.
+	"20060102T150405Z",
+	time.RFC1123,
+	time.RFC1123Z,
+	// Add new AMZ date formats here.
+}
+
+// ErrMalformedDate always returned for dates that cannot be parsed.
+var ErrMalformedDate = errors.New("malformed date")
+
+// Parse parses date string via supported amz date formats.
+func Parse(amzDateStr string) (time.Time, error) {
+	for _, dateFormat := range amzDateFormats {
+		amzDate, err := time.Parse(dateFormat, amzDateStr)
+		if err == nil {
+			return amzDate, nil
+		}
+	}
+	return time.Time{}, ErrMalformedDate
+}
+
+var httpTimeFormats = []string{
+	// Do not chagne this order, http time format dates
+	// are usually in http.TimeFormat however there are
+	// situations where for example aws-sdk-java doesn't
+	// send the correct format.
+	http.TimeFormat,
+	"Mon, 2 Jan 2006 15:04:05 GMT",
+}
+
+// ParseHeader parses http.TimeFormat with an acceptable
+// extension for http.TimeFormat - return time might be zero
+// if the timeStr is invalid.
+func ParseHeader(timeStr string) (time.Time, error) {
+	for _, dateFormat := range httpTimeFormats {
+		t, err := time.Parse(dateFormat, timeStr)
+		if err == nil {
+			return t, nil
+		}
+	}
+	return time.Time{}, ErrMalformedDate
+}