feat: implements host-style bucket addressing in the gateway.

Closes #803

Implements host-style bucket addressing in the gateway. This feature can be enabled by running the gateway with the `--virtual-domain` flag and specifying a virtual domain name.
Example:

```bash
    ./versitygw -a user -s secret --virtual-domain localhost:7070 posix /tmp/vgw
```

The implementation follows this approach: it introduces a middleware (`HostStyleParser`) that parses the bucket name from the `Host` header and appends it to the URL path. This effectively transforms the request into a path-style bucket addressing format, which the gateway already supports. With this design, the gateway can handle both path-style and host-style requests when running in host-style mode.

For local testing, one can either set up a local DNS server to wildcard-match all subdomains of a specified domain and resolve them to the local IP address, or manually add entries to `/etc/hosts` to resolve bucket-prefixed hosts to the server IP (e.g., `127.0.0.1`).

tests/integration/s3conf.go

@@ -36,8 +36,8 @@ type S3Conf struct {
 	awsSecret         string
 	awsRegion         string
 	endpoint          string
+	hostStyle         bool
 	checksumDisable   bool
-	pathStyle         bool
 	PartSize          int64
 	Concurrency       int
 	debug             bool
@@ -87,8 +87,8 @@ func WithEndpoint(e string) Option {
 func WithDisableChecksum() Option {
 	return func(s *S3Conf) { s.checksumDisable = true }
 }
-func WithPathStyle() Option {
-	return func(s *S3Conf) { s.pathStyle = true }
+func WithHostStyle() Option {
+	return func(s *S3Conf) { s.hostStyle = true }
 }
 func WithPartSize(p int64) Option {
 	return func(s *S3Conf) { s.PartSize = p }
@@ -122,7 +122,12 @@ func (c *S3Conf) getCreds() credentials.StaticCredentialsProvider {
 }
 
 func (c *S3Conf) GetClient() *s3.Client {
-	return s3.NewFromConfig(c.Config())
+	return s3.NewFromConfig(c.Config(), func(o *s3.Options) {
+		if c.hostStyle {
+			o.BaseEndpoint = &c.endpoint
+			o.UsePathStyle = false
+		}
+	})
 }
 
 func (c *S3Conf) Config() aws.Config {

tests/integration/tests.go

@@ -1406,7 +1406,7 @@ func PresignedAuth_UploadPart(s *S3Conf) error {
 			return err
 		}
 
-		clt := s3.NewFromConfig(s.Config())
+		clt := s.GetClient()
 		mp, err := createMp(clt, bucket, key)
 		if err != nil {
 			return err
@@ -1600,7 +1600,7 @@ func CreateBucket_ownership_with_acl(s *S3Conf) error {
 	testName := "CreateBucket_ownership_with_acl"
 
 	runF(testName)
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err := client.CreateBucket(ctx, &s3.CreateBucketInput{
@@ -1697,7 +1697,7 @@ func CreateBucket_non_default_acl(s *S3Conf) error {
 	}
 
 	bucket := getBucketName()
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err = client.CreateBucket(ctx, &s3.CreateBucketInput{
@@ -1743,7 +1743,7 @@ func CreateBucket_default_object_lock(s *S3Conf) error {
 	bucket := getBucketName()
 	lockEnabled := true
 
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err := client.CreateBucket(ctx, &s3.CreateBucketInput{
@@ -1863,7 +1863,7 @@ func ListBuckets_as_user(s *S3Conf) error {
 			return err
 		}
 
-		userClient := s3.NewFromConfig(cfg.Config())
+		userClient := cfg.GetClient()
 
 		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 		out, err := userClient.ListBuckets(ctx, &s3.ListBucketsInput{})
@@ -1938,7 +1938,7 @@ func ListBuckets_as_admin(s *S3Conf) error {
 			return err
 		}
 
-		adminClient := s3.NewFromConfig(cfg.Config())
+		adminClient := cfg.GetClient()
 
 		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 		out, err := adminClient.ListBuckets(ctx, &s3.ListBucketsInput{})
@@ -2216,7 +2216,7 @@ func DeleteBucket_non_existing_bucket(s *S3Conf) error {
 	testName := "DeleteBucket_non_existing_bucket"
 	runF(testName)
 	bucket := getBucketName()
-	s3client := s3.NewFromConfig(s.Config())
+	s3client := s.GetClient()
 
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err := s3client.DeleteBucket(ctx, &s3.DeleteBucketInput{
@@ -3008,7 +3008,7 @@ func PutObject_with_object_lock(s *S3Conf) error {
 	runF(testName)
 	bucket, obj, lockStatus := getBucketName(), "my-obj", true
 
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err := client.CreateBucket(ctx, &s3.CreateBucketInput{
 		Bucket:                     &bucket,
@@ -3414,7 +3414,7 @@ func PutObject_racey_success(s *S3Conf) error {
 	runF(testName)
 	bucket, obj, lockStatus := getBucketName(), "my-obj", true
 
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 	_, err := client.CreateBucket(ctx, &s3.CreateBucketInput{
 		Bucket:                     &bucket,
@@ -3471,7 +3471,7 @@ func PutObject_invalid_credentials(s *S3Conf) error {
 	return actionHandler(s, testName, func(s3client *s3.Client, bucket string) error {
 		newconf := *s
 		newconf.awsSecret = newconf.awsSecret + "badpassword"
-		client := s3.NewFromConfig(newconf.Config())
+		client := newconf.GetClient()
 		_, err := putObjects(client, []string{"my-obj"}, bucket)
 		return checkApiErr(err, s3err.GetAPIError(s3err.ErrSignatureDoesNotMatch))
 	})
@@ -6301,7 +6301,7 @@ func CopyObject_not_owned_source_bucket(s *S3Conf) error {
 		cfg.awsID = usr.access
 		cfg.awsSecret = usr.secret
 
-		userS3Client := s3.NewFromConfig(cfg.Config())
+		userS3Client := cfg.GetClient()
 
 		err = createUsers(s, []user{usr})
 		if err != nil {
@@ -11974,7 +11974,7 @@ func PutBucketAcl_success_access_denied(s *S3Conf) error {
 		newConf := *s
 		newConf.awsID = "grt1"
 		newConf.awsSecret = "grt1secret"
-		userClient := s3.NewFromConfig(newConf.Config())
+		userClient := newConf.GetClient()
 
 		_, err = putObjects(userClient, []string{"my-obj"}, bucket)
 		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrAccessDenied)); err != nil {
@@ -12006,7 +12006,7 @@ func PutBucketAcl_success_canned_acl(s *S3Conf) error {
 		newConf := *s
 		newConf.awsID = "grt1"
 		newConf.awsSecret = "grt1secret"
-		userClient := s3.NewFromConfig(newConf.Config())
+		userClient := newConf.GetClient()
 
 		_, err = putObjects(userClient, []string{"my-obj"}, bucket)
 		if err != nil {
@@ -12038,7 +12038,7 @@ func PutBucketAcl_success_acp(s *S3Conf) error {
 		newConf := *s
 		newConf.awsID = "grt1"
 		newConf.awsSecret = "grt1secret"
-		userClient := s3.NewFromConfig(newConf.Config())
+		userClient := newConf.GetClient()
 
 		_, err = putObjects(userClient, []string{"my-obj"}, bucket)
 		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrAccessDenied)); err != nil {
@@ -12092,7 +12092,7 @@ func PutBucketAcl_success_grants(s *S3Conf) error {
 		newConf := *s
 		newConf.awsID = "grt1"
 		newConf.awsSecret = "grt1secret"
-		userClient := s3.NewFromConfig(newConf.Config())
+		userClient := newConf.GetClient()
 
 		_, err = putObjects(userClient, []string{"my-obj"}, bucket)
 		if err != nil {
@@ -12286,7 +12286,7 @@ func GetBucketAcl_access_denied(s *S3Conf) error {
 		newConf := *s
 		newConf.awsID = "grt1"
 		newConf.awsSecret = "grt1secret"
-		userClient := s3.NewFromConfig(newConf.Config())
+		userClient := newConf.GetClient()
 
 		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
 		_, err = userClient.GetBucketAcl(ctx, &s3.GetBucketAclInput{
@@ -14863,7 +14863,7 @@ func AccessControl_default_ACL_user_access_denied(s *S3Conf) error {
 		cfg.awsID = usr.access
 		cfg.awsSecret = usr.secret
 
-		_, err = putObjects(s3.NewFromConfig(cfg.Config()), []string{"my-obj"}, bucket)
+		_, err = putObjects(cfg.GetClient(), []string{"my-obj"}, bucket)
 		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrAccessDenied)); err != nil {
 			return err
 		}
@@ -14889,7 +14889,7 @@ func AccessControl_default_ACL_userplus_access_denied(s *S3Conf) error {
 		cfg.awsID = usr.access
 		cfg.awsSecret = usr.secret
 
-		_, err = putObjects(s3.NewFromConfig(cfg.Config()), []string{"my-obj"}, bucket)
+		_, err = putObjects(cfg.GetClient(), []string{"my-obj"}, bucket)
 		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrAccessDenied)); err != nil {
 			return err
 		}
@@ -14915,7 +14915,7 @@ func AccessControl_default_ACL_admin_successful_access(s *S3Conf) error {
 		cfg.awsID = admin.access
 		cfg.awsSecret = admin.secret
 
-		_, err = putObjects(s3.NewFromConfig(cfg.Config()), []string{"my-obj"}, bucket)
+		_, err = putObjects(cfg.GetClient(), []string{"my-obj"}, bucket)
 		if err != nil {
 			return err
 		}

tests/integration/utils.go

@@ -59,7 +59,7 @@ func getBucketName() string {
 }
 
 func setup(s *S3Conf, bucket string, opts ...setupOpt) error {
-	s3client := s3.NewFromConfig(s.Config())
+	s3client := s.GetClient()
 
 	cfg := new(setupCfg)
 	for _, opt := range opts {
@@ -95,7 +95,7 @@ func setup(s *S3Conf, bucket string, opts ...setupOpt) error {
 }
 
 func teardown(s *S3Conf, bucket string) error {
-	s3client := s3.NewFromConfig(s.Config())
+	s3client := s.GetClient()
 
 	deleteObject := func(bucket, key, versionId *string) error {
 		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
@@ -200,7 +200,7 @@ func actionHandler(s *S3Conf, testName string, handler func(s3client *s3.Client,
 		failF("%v: failed to create a bucket: %v", testName, err)
 		return fmt.Errorf("%v: failed to create a bucket: %w", testName, err)
 	}
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 	handlerErr := handler(client, bucketName)
 	if handlerErr != nil {
 		failF("%v: %v", testName, handlerErr)
@@ -222,7 +222,7 @@ func actionHandler(s *S3Conf, testName string, handler func(s3client *s3.Client,
 
 func actionHandlerNoSetup(s *S3Conf, testName string, handler func(s3client *s3.Client, bucket string) error, _ ...setupOpt) error {
 	runF(testName)
-	client := s3.NewFromConfig(s.Config())
+	client := s.GetClient()
 	handlerErr := handler(client, "")
 	if handlerErr != nil {
 		failF("%v: %v", testName, handlerErr)
@@ -263,7 +263,7 @@ func authHandler(s *S3Conf, cfg *authConfig, handler func(req *http.Request) err
 
 func presignedAuthHandler(s *S3Conf, testName string, handler func(client *s3.PresignClient) error) error {
 	runF(testName)
-	clt := s3.NewPresignClient(s3.NewFromConfig(s.Config()))
+	clt := s3.NewPresignClient(s.GetClient())
 
 	err := handler(clt)
 	if err != nil {
@@ -989,7 +989,7 @@ func getUserS3Client(usr user, cfg *S3Conf) *s3.Client {
 	config.awsID = usr.access
 	config.awsSecret = usr.secret
 
-	return s3.NewFromConfig(config.Config())
+	return config.GetClient()
 }
 
 // if true enables, otherwise disables