private/protocol: add support for UTC offset for IOS datetime formats

CHANGELOG_PENDING.md

@@ -3,3 +3,5 @@
 ### SDK Enhancements
 
 ### SDK Bugs
+* `private/protocol`: Add support for UTC offset for ISO8601 datetime formats ([#3960](https://github.com/aws/aws-sdk-go/pull/3960))
+  * Updates the SDK's parsing of ISO8601 date time formats to support UTC offsets.

private/protocol/timestamp.go

@@ -1,6 +1,8 @@
 package protocol
 
 import (
+	"bytes"
+	"fmt"
 	"math"
 	"strconv"
 	"time"
@@ -19,7 +21,9 @@ const (
 // Output time is intended to not contain decimals
 const (
 	// RFC 7231#section-7.1.1.1 timetamp format. e.g Tue, 29 Apr 2014 18:30:38 GMT
-	RFC822TimeFormat = "Mon, 2 Jan 2006 15:04:05 GMT"
+	RFC822TimeFormat                           = "Mon, 2 Jan 2006 15:04:05 GMT"
+	rfc822TimeFormatSingleDigitDay             = "Mon, _2 Jan 2006 15:04:05 GMT"
+	rfc822TimeFormatSingleDigitDayTwoDigitYear = "Mon, _2 Jan 06 15:04:05 GMT"
 
 	// This format is used for output time without seconds precision
 	RFC822OutputTimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
@@ -67,10 +71,20 @@ func FormatTime(name string, t time.Time) string {
 // the time if it was able to be parsed, and fails otherwise.
 func ParseTime(formatName, value string) (time.Time, error) {
 	switch formatName {
-	case RFC822TimeFormatName:
-		return time.Parse(RFC822TimeFormat, value)
-	case ISO8601TimeFormatName:
-		return time.Parse(ISO8601TimeFormat, value)
+	case RFC822TimeFormatName: // Smithy HTTPDate format
+		return tryParse(value,
+			RFC822TimeFormat,
+			rfc822TimeFormatSingleDigitDay,
+			rfc822TimeFormatSingleDigitDayTwoDigitYear,
+			time.RFC850,
+			time.ANSIC,
+		)
+	case ISO8601TimeFormatName: // Smithy DateTime format
+		return tryParse(value,
+			ISO8601TimeFormat,
+			time.RFC3339Nano,
+			time.RFC3339,
+		)
 	case UnixTimeFormatName:
 		v, err := strconv.ParseFloat(value, 64)
 		_, dec := math.Modf(v)
@@ -83,3 +97,36 @@ func ParseTime(formatName, value string) (time.Time, error) {
 		panic("unknown timestamp format name, " + formatName)
 	}
 }
+
+func tryParse(v string, formats ...string) (time.Time, error) {
+	var errs parseErrors
+	for _, f := range formats {
+		t, err := time.Parse(f, v)
+		if err != nil {
+			errs = append(errs, parseError{
+				Format: f,
+				Err:    err,
+			})
+			continue
+		}
+		return t, nil
+	}
+
+	return time.Time{}, fmt.Errorf("unable to parse time string, %v", errs)
+}
+
+type parseErrors []parseError
+
+func (es parseErrors) Error() string {
+	var s bytes.Buffer
+	for _, e := range es {
+		fmt.Fprintf(&s, "\n * %q: %v", e.Format, e.Err)
+	}
+
+	return "parse errors:" + s.String()
+}
+
+type parseError struct {
+	Format string
+	Err    error
+}

private/protocol/timestamp_test.go

@@ -80,21 +80,46 @@ func TestParseTime(t *testing.T) {
 			input:          "946845296.1229999",
 			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, .123e9, time.UTC),
 		},
-		"ISO8601Test1": {
+		"ISO8601Test milliseconds": {
 			formatName:     ISO8601TimeFormatName,
 			input:          "2000-01-02T20:34:56.123Z",
 			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, .123e9, time.UTC),
 		},
-		"ISO8601Test2": {
+		"ISO8601Test nanoseconds": {
 			formatName:     ISO8601TimeFormatName,
 			input:          "2000-01-02T20:34:56.123456789Z",
 			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, .123456789e9, time.UTC),
 		},
-		"RFC822Test1": {
+		"ISO8601Test millisecond utc offset": {
+			formatName:     ISO8601TimeFormatName,
+			input:          "2000-01-02T20:34:56.123-07:00",
+			expectedOutput: time.Date(2000, time.January, 3, 3, 34, 56, .123e9, time.UTC),
+		},
+		"ISO8601Test millisecond positive utc offset": {
+			formatName:     ISO8601TimeFormatName,
+			input:          "2000-01-02T20:34:56.123+07:00",
+			expectedOutput: time.Date(2000, time.January, 2, 13, 34, 56, .123e9, time.UTC),
+		},
+		"ISO8601Test nanosecond utc offset": {
+			formatName:     ISO8601TimeFormatName,
+			input:          "2000-01-02T20:34:56.123456789-07:00",
+			expectedOutput: time.Date(2000, time.January, 3, 3, 34, 56, .123456789e9, time.UTC),
+		},
+		"RFC822Test single digit day": {
 			formatName:     RFC822TimeFormatName,
 			input:          "Sun, 2 Jan 2000 20:34:56 GMT",
 			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, 0, time.UTC),
 		},
+		"RFC822Test two digit day": {
+			formatName:     RFC822TimeFormatName,
+			input:          "Sun, 02 Jan 2000 20:34:56 GMT",
+			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, 0, time.UTC),
+		},
+		"RFC822Test two digit day year": {
+			formatName:     RFC822TimeFormatName,
+			input:          "Sun, 2 Jan 00 20:34:56 GMT",
+			expectedOutput: time.Date(2000, time.January, 2, 20, 34, 56, 0, time.UTC),
+		},
 	}
 
 	for name, c := range cases {