feat: add option to disable strict bucket name checks

Some systems may choose to allow non-aws compliant bucket names
and/or handle the bucket naem validation in the backend instead.
This adds the option to turn off the strict bucket name validation
checks in the frontend API handlers.

When frontend bucket name validation is disabled, we need to do
sanity checks for posix compliant names in the posix/scoutfs
backends. This is automatically enabled when strict bucket
name validation is disabled.

Fixes #1564

s3api/utils/utils.go

@@ -26,6 +26,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/service/s3/types"
@@ -41,6 +42,16 @@ var (
 	bucketNameIpRegexp = regexp.MustCompile(`^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$`)
 )
 
+var strictBucketNameValidation atomic.Bool
+
+func init() {
+	strictBucketNameValidation.Store(true)
+}
+
+func SetBucketNameValidationStrict(strict bool) {
+	strictBucketNameValidation.Store(strict)
+}
+
 func GetUserMetaData(headers *fasthttp.RequestHeader) (metadata map[string]string) {
 	metadata = make(map[string]string)
 	headers.DisableNormalizing()
@@ -209,6 +220,10 @@ func StreamResponseBody(ctx *fiber.Ctx, rdr io.ReadCloser, bodysize int) {
 }
 
 func IsValidBucketName(bucket string) bool {
+	if !strictBucketNameValidation.Load() {
+		return true
+	}
+
 	if len(bucket) < 3 || len(bucket) > 63 {
 		debuglogger.Logf("bucket name length should be in 3-63 range, got: %v\n", len(bucket))
 		return false

s3api/utils/utils_test.go

@@ -231,6 +231,28 @@ func TestIsValidBucketName(t *testing.T) {
 	}
 }
 
+func TestSetBucketNameValidationStrict(t *testing.T) {
+	SetBucketNameValidationStrict(true)
+	t.Cleanup(func() {
+		SetBucketNameValidationStrict(true)
+	})
+
+	invalidBucket := "Invalid_Bucket"
+	if IsValidBucketName(invalidBucket) {
+		t.Fatalf("expected %q to be invalid with strict validation", invalidBucket)
+	}
+
+	SetBucketNameValidationStrict(false)
+	if !IsValidBucketName(invalidBucket) {
+		t.Fatalf("expected %q to be accepted when strict validation disabled", invalidBucket)
+	}
+
+	SetBucketNameValidationStrict(true)
+	if IsValidBucketName(invalidBucket) {
+		t.Fatalf("expected %q to be invalid after re-enabling strict validation", invalidBucket)
+	}
+}
+
 func TestParseUint(t *testing.T) {
 	type args struct {
 		str string