[feature] S3 support (#674)

* feat: vendor minio client

* feat: introduce storage package with s3 support

* feat: serve s3 files directly

this saves a lot of bandwith as the files are fetched from the object
store directly

* fix: use explicit local storage in tests

* feat: integrate s3 storage with the main server

* fix: add s3 config to cli tests

* docs: explicitly set values in example config

also adds license header to the storage package

* fix: use better http status code on s3 redirect

HTTP 302 Found is the best fit, as it signifies that the resource
requested was found but not under its presumed URL

307/TemporaryRedirect would mean that this resource is usually located
here, not in this case

303/SeeOther indicates that the redirection does not link to the
requested resource but to another page

* refactor: use context in storage driver interface

1 files changed, 152 insertions, 0 deletions

diff --git a/vendor/github.com/minio/minio-go/v7/api-get-object-acl.go b/vendor/github.com/minio/minio-go/v7/api-get-object-acl.go
new file mode 100644
index 000000000..9041d99e9
--- /dev/null
+++ b/vendor/github.com/minio/minio-go/v7/api-get-object-acl.go
@@ -0,0 +1,152 @@
+/*
+ * MinIO Go Library for Amazon S3 Compatible Cloud Storage
+ * Copyright 2018 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package minio
+
+import (
+	"context"
+	"encoding/xml"
+	"net/http"
+	"net/url"
+)
+
+// Grantee represents the person being granted permissions.
+type Grantee struct {
+	XMLName     xml.Name `xml:"Grantee"`
+	ID          string   `xml:"ID"`
+	DisplayName string   `xml:"DisplayName"`
+	URI         string   `xml:"URI"`
+}
+
+// Grant holds grant information
+type Grant struct {
+	XMLName    xml.Name `xml:"Grant"`
+	Grantee    Grantee
+	Permission string `xml:"Permission"`
+}
+
+// AccessControlList contains the set of grantees and the permissions assigned to each grantee.
+type AccessControlList struct {
+	XMLName    xml.Name `xml:"AccessControlList"`
+	Grant      []Grant
+	Permission string `xml:"Permission"`
+}
+
+type accessControlPolicy struct {
+	XMLName           xml.Name `xml:"AccessControlPolicy"`
+	Owner             Owner
+	AccessControlList AccessControlList
+}
+
+// GetObjectACL get object ACLs
+func (c *Client) GetObjectACL(ctx context.Context, bucketName, objectName string) (*ObjectInfo, error) {
+	resp, err := c.executeMethod(ctx, http.MethodGet, requestMetadata{
+		bucketName: bucketName,
+		objectName: objectName,
+		queryValues: url.Values{
+			"acl": []string{""},
+		},
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer closeResponse(resp)
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, httpRespToErrorResponse(resp, bucketName, objectName)
+	}
+
+	res := &accessControlPolicy{}
+
+	if err := xmlDecoder(resp.Body, res); err != nil {
+		return nil, err
+	}
+
+	objInfo, err := c.StatObject(ctx, bucketName, objectName, StatObjectOptions{})
+	if err != nil {
+		return nil, err
+	}
+
+	objInfo.Owner.DisplayName = res.Owner.DisplayName
+	objInfo.Owner.ID = res.Owner.ID
+
+	objInfo.Grant = append(objInfo.Grant, res.AccessControlList.Grant...)
+
+	cannedACL := getCannedACL(res)
+	if cannedACL != "" {
+		objInfo.Metadata.Add("X-Amz-Acl", cannedACL)
+		return &objInfo, nil
+	}
+
+	grantACL := getAmzGrantACL(res)
+	for k, v := range grantACL {
+		objInfo.Metadata[k] = v
+	}
+
+	return &objInfo, nil
+}
+
+func getCannedACL(aCPolicy *accessControlPolicy) string {
+	grants := aCPolicy.AccessControlList.Grant
+
+	switch {
+	case len(grants) == 1:
+		if grants[0].Grantee.URI == "" && grants[0].Permission == "FULL_CONTROL" {
+			return "private"
+		}
+	case len(grants) == 2:
+		for _, g := range grants {
+			if g.Grantee.URI == "http://acs.amazonaws.com/groups/global/AuthenticatedUsers" && g.Permission == "READ" {
+				return "authenticated-read"
+			}
+			if g.Grantee.URI == "http://acs.amazonaws.com/groups/global/AllUsers" && g.Permission == "READ" {
+				return "public-read"
+			}
+			if g.Permission == "READ" && g.Grantee.ID == aCPolicy.Owner.ID {
+				return "bucket-owner-read"
+			}
+		}
+	case len(grants) == 3:
+		for _, g := range grants {
+			if g.Grantee.URI == "http://acs.amazonaws.com/groups/global/AllUsers" && g.Permission == "WRITE" {
+				return "public-read-write"
+			}
+		}
+	}
+	return ""
+}
+
+func getAmzGrantACL(aCPolicy *accessControlPolicy) map[string][]string {
+	grants := aCPolicy.AccessControlList.Grant
+	res := map[string][]string{}
+
+	for _, g := range grants {
+		switch {
+		case g.Permission == "READ":
+			res["X-Amz-Grant-Read"] = append(res["X-Amz-Grant-Read"], "id="+g.Grantee.ID)
+		case g.Permission == "WRITE":
+			res["X-Amz-Grant-Write"] = append(res["X-Amz-Grant-Write"], "id="+g.Grantee.ID)
+		case g.Permission == "READ_ACP":
+			res["X-Amz-Grant-Read-Acp"] = append(res["X-Amz-Grant-Read-Acp"], "id="+g.Grantee.ID)
+		case g.Permission == "WRITE_ACP":
+			res["X-Amz-Grant-Write-Acp"] = append(res["X-Amz-Grant-Write-Acp"], "id="+g.Grantee.ID)
+		case g.Permission == "FULL_CONTROL":
+			res["X-Amz-Grant-Full-Control"] = append(res["X-Amz-Grant-Full-Control"], "id="+g.Grantee.ID)
+		}
+	}
+	return res
+}