Merge pull request #19 from tilezen/zerebubuth/use-http-compliant-tim…

…estamp-format

Use HTTP compliant timestamp format string

tapalcatl_server/handler.go

@@ -462,7 +462,11 @@ func MetatileHandler(p Parser, metatileSize int, mimeMap map[string]string, stor
 		headers := rw.Header()
 		headers.Set("Content-Type", parseResult.ContentType)
 		if lastMod := storageResp.LastModified; lastMod != nil {
-			lastModifiedFormatted := lastMod.Format(time.RFC1123Z)
+			// important! we must format times in an HTTP-compliant way, which
+			// apparently doesn't match any existing Go time format string, so the
+			// recommended way is to switch to UTC and use the format string that
+			// the net/http package exposes.
+			lastModifiedFormatted := lastMod.UTC().Format(http.TimeFormat)
 			headers.Set("Last-Modified", lastModifiedFormatted)
 			reqState.storageMetadata.hasLastModified = true
 		}

tapalcatl_server/handler_test.go

@@ -129,8 +129,8 @@ func TestHandlerHit(t *testing.T) {
 	}
 
 	etag := "1234"
-	lastModifiedStr := "Thu, 17 Nov 2016 12:27:00 +0000"
-	lastModified, err := time.Parse(time.RFC1123Z, lastModifiedStr)
+	lastModifiedStr := "Thu, 17 Nov 2016 12:27:00 GMT"
+	lastModified, err := time.Parse(http.TimeFormat, lastModifiedStr)
 	if err != nil {
 		t.Fatalf("Couldn't parse time %s: %s", lastModifiedStr, err)
 	}

tapalcatl_server/server.go

@@ -87,6 +87,7 @@ func (h *handlerConfig) Set(line string) error {
 // try and parse a range of different date formats which are allowed by HTTP.
 func parseHTTPDates(date string) (*time.Time, error) {
 	time_layouts := []string{
+		http.TimeFormat,
 		time.RFC1123, time.RFC1123Z,
 		time.RFC822, time.RFC822Z,
 		time.RFC850, time.ANSIC,
@@ -103,7 +104,7 @@ func parseHTTPDates(date string) (*time.Time, error) {
 	}
 
 	// give the error for our preferred format
-	_, err = time.Parse(time.RFC1123, date)
+	_, err = time.Parse(http.TimeFormat, date)
 	return nil, err
 }
 

tapalcatl_server/storage_test.go

@@ -6,6 +6,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/aws/aws-sdk-go/service/s3/s3iface"
 	"github.com/tilezen/tapalcatl"
+	"net/http"
 	"testing"
 	"time"
 )
@@ -95,9 +96,11 @@ func TestS3Storage(t *testing.T) {
 	if lastMod == nil {
 		t.Fatalf("Missing last modified from storage")
 	}
-	// should be formatted in RFC 822 / 1123 format
-	expLastModStr := "Thu, 17 Nov 2016 12:27:00 +0000"
-	lastModStr := lastMod.Format(time.RFC1123Z)
+	// should be formatted in HTTP standard way, which means the GMT on the end
+	// is intentional, and shouldn't be UTC or +0000 or Z, despite all of those
+	// being better choices.
+	expLastModStr := "Thu, 17 Nov 2016 12:27:00 GMT"
+	lastModStr := lastMod.UTC().Format(http.TimeFormat)
 	if expLastModStr != lastModStr {
 		t.Fatalf("Expected Last-Modified to be %#v, but got %#v", expLastModStr, lastModStr)
 	}