1 files changed, 162 insertions, 0 deletions
diff --git a/pkg/credentials/sts_client_grants.go b/pkg/credentials/sts_client_grants.go
new file mode 100644
index 0000000..03134c3
--- /dev/null
+++ b/pkg/credentials/sts_client_grants.go
@@ -0,0 +1,162 @@
+/*
+ * MinIO Go Library for Amazon S3 Compatible Cloud Storage
+ * Copyright 2019 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 credentials
+
+import (
+	"encoding/xml"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+// AssumedRoleUser - The identifiers for the temporary security credentials that
+// the operation returns. Please also see https://docs.aws.amazon.com/goto/WebAPI/sts-2011-06-15/AssumedRoleUser
+type AssumedRoleUser struct {
+	Arn           string
+	AssumedRoleID string `xml:"AssumeRoleId"`
+}
+
+// AssumeRoleWithClientGrantsResponse contains the result of successful AssumeRoleWithClientGrants request.
+type AssumeRoleWithClientGrantsResponse struct {
+	XMLName          xml.Name           `xml:"https://sts.amazonaws.com/doc/2011-06-15/ AssumeRoleWithClientGrantsResponse" json:"-"`
+	Result           ClientGrantsResult `xml:"AssumeRoleWithClientGrantsResult"`
+	ResponseMetadata struct {
+		RequestID string `xml:"RequestId,omitempty"`
+	} `xml:"ResponseMetadata,omitempty"`
+}
+
+// ClientGrantsResult - Contains the response to a successful AssumeRoleWithClientGrants
+// request, including temporary credentials that can be used to make MinIO API requests.
+type ClientGrantsResult struct {
+	AssumedRoleUser AssumedRoleUser `xml:",omitempty"`
+	Audience        string          `xml:",omitempty"`
+	Credentials     struct {
+		AccessKey    string    `xml:"AccessKeyId" json:"accessKey,omitempty"`
+		SecretKey    string    `xml:"SecretAccessKey" json:"secretKey,omitempty"`
+		Expiration   time.Time `xml:"Expiration" json:"expiration,omitempty"`
+		SessionToken string    `xml:"SessionToken" json:"sessionToken,omitempty"`
+	} `xml:",omitempty"`
+	PackedPolicySize             int    `xml:",omitempty"`
+	Provider                     string `xml:",omitempty"`
+	SubjectFromClientGrantsToken string `xml:",omitempty"`
+}
+
+// ClientGrantsToken - client grants token with expiry.
+type ClientGrantsToken struct {
+	Token  string
+	Expiry int
+}
+
+// A STSClientGrants retrieves credentials from MinIO service, and keeps track if
+// those credentials are expired.
+type STSClientGrants struct {
+	Expiry
+
+	// Required http Client to use when connecting to MinIO STS service.
+	Client *http.Client
+
+	// MinIO endpoint to fetch STS credentials.
+	stsEndpoint string
+
+	// getClientGrantsTokenExpiry function to retrieve tokens
+	// from IDP This function should return two values one is
+	// accessToken which is a self contained access token (JWT)
+	// and second return value is the expiry associated with
+	// this token. This is a customer provided function and
+	// is mandatory.
+	getClientGrantsTokenExpiry func() (*ClientGrantsToken, error)
+}
+
+// NewSTSClientGrants returns a pointer to a new
+// Credentials object wrapping the STSClientGrants.
+func NewSTSClientGrants(stsEndpoint string, getClientGrantsTokenExpiry func() (*ClientGrantsToken, error)) (*Credentials, error) {
+	if stsEndpoint == "" {
+		return nil, errors.New("STS endpoint cannot be empty")
+	}
+	if getClientGrantsTokenExpiry == nil {
+		return nil, errors.New("Client grants access token and expiry retrieval function should be defined")
+	}
+	return New(&STSClientGrants{
+		Client: &http.Client{
+			Transport: http.DefaultTransport,
+		},
+		stsEndpoint:                stsEndpoint,
+		getClientGrantsTokenExpiry: getClientGrantsTokenExpiry,
+	}), nil
+}
+
+func getClientGrantsCredentials(clnt *http.Client, endpoint string,
+	getClientGrantsTokenExpiry func() (*ClientGrantsToken, error)) (AssumeRoleWithClientGrantsResponse, error) {
+
+	accessToken, err := getClientGrantsTokenExpiry()
+	if err != nil {
+		return AssumeRoleWithClientGrantsResponse{}, err
+	}
+
+	v := url.Values{}
+	v.Set("Action", "AssumeRoleWithClientGrants")
+	v.Set("Token", accessToken.Token)
+	v.Set("DurationSeconds", fmt.Sprintf("%d", accessToken.Expiry))
+	v.Set("Version", "2011-06-15")
+
+	u, err := url.Parse(endpoint)
+	if err != nil {
+		return AssumeRoleWithClientGrantsResponse{}, err
+	}
+	u.RawQuery = v.Encode()
+
+	req, err := http.NewRequest("POST", u.String(), nil)
+	if err != nil {
+		return AssumeRoleWithClientGrantsResponse{}, err
+	}
+	resp, err := clnt.Do(req)
+	if err != nil {
+		return AssumeRoleWithClientGrantsResponse{}, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return AssumeRoleWithClientGrantsResponse{}, errors.New(resp.Status)
+	}
+
+	a := AssumeRoleWithClientGrantsResponse{}
+	if err = xml.NewDecoder(resp.Body).Decode(&a); err != nil {
+		return AssumeRoleWithClientGrantsResponse{}, err
+	}
+	return a, nil
+}
+
+// Retrieve retrieves credentials from the MinIO service.
+// Error will be returned if the request fails.
+func (m *STSClientGrants) Retrieve() (Value, error) {
+	a, err := getClientGrantsCredentials(m.Client, m.stsEndpoint, m.getClientGrantsTokenExpiry)
+	if err != nil {
+		return Value{}, err
+	}
+
+	// Expiry window is set to 10secs.
+	m.SetExpiration(a.Result.Credentials.Expiration, DefaultExpiryWindow)
+
+	return Value{
+		AccessKeyID:     a.Result.Credentials.AccessKey,
+		SecretAccessKey: a.Result.Credentials.SecretKey,
+		SessionToken:    a.Result.Credentials.SessionToken,
+		SignerType:      SignatureV4,
+	}, nil
+}