server: Move all the top level files into cmd folder. (#2490)

This change brings a change which was done for the 'mc'
package to allow for clean repo and have a cleaner
github drop in experience.

cmd/auth-handler.go

@@ -0,0 +1,203 @@
+/*
+ * Minio Cloud Storage, (C) 2015, 2016 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 cmd
+
+import (
+	"bytes"
+	"crypto/md5"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// Verify if the request http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD"
+func isRequestUnsignedPayload(r *http.Request) bool {
+	return r.Header.Get("x-amz-content-sha256") == unsignedPayload
+}
+
+// Verify if request has JWT.
+func isRequestJWT(r *http.Request) bool {
+	return strings.HasPrefix(r.Header.Get("Authorization"), jwtAlgorithm)
+}
+
+// Verify if request has AWS Signature Version '4'.
+func isRequestSignatureV4(r *http.Request) bool {
+	return strings.HasPrefix(r.Header.Get("Authorization"), signV4Algorithm)
+}
+
+// Verify if request has AWS PreSign Version '4'.
+func isRequestPresignedSignatureV4(r *http.Request) bool {
+	_, ok := r.URL.Query()["X-Amz-Credential"]
+	return ok
+}
+
+// Verify if request has AWS Post policy Signature Version '4'.
+func isRequestPostPolicySignatureV4(r *http.Request) bool {
+	return strings.Contains(r.Header.Get("Content-Type"), "multipart/form-data") && r.Method == "POST"
+}
+
+// Verify if the request has AWS Streaming Signature Version '4'. This is only valid for 'PUT' operation.
+func isRequestSignStreamingV4(r *http.Request) bool {
+	return r.Header.Get("x-amz-content-sha256") == streamingContentSHA256 && r.Method == "PUT"
+}
+
+// Authorization type.
+type authType int
+
+// List of all supported auth types.
+const (
+	authTypeUnknown authType = iota
+	authTypeAnonymous
+	authTypePresigned
+	authTypePostPolicy
+	authTypeStreamingSigned
+	authTypeSigned
+	authTypeJWT
+)
+
+// Get request authentication type.
+func getRequestAuthType(r *http.Request) authType {
+	if isRequestSignStreamingV4(r) {
+		return authTypeStreamingSigned
+	} else if isRequestSignatureV4(r) {
+		return authTypeSigned
+	} else if isRequestPresignedSignatureV4(r) {
+		return authTypePresigned
+	} else if isRequestJWT(r) {
+		return authTypeJWT
+	} else if isRequestPostPolicySignatureV4(r) {
+		return authTypePostPolicy
+	} else if _, ok := r.Header["Authorization"]; !ok {
+		return authTypeAnonymous
+	}
+	return authTypeUnknown
+}
+
+// sum256 calculate sha256 sum for an input byte array
+func sum256(data []byte) []byte {
+	hash := sha256.New()
+	hash.Write(data)
+	return hash.Sum(nil)
+}
+
+// sumMD5 calculate md5 sum for an input byte array
+func sumMD5(data []byte) []byte {
+	hash := md5.New()
+	hash.Write(data)
+	return hash.Sum(nil)
+}
+
+// Verify if request has valid AWS Signature Version '4'.
+func isReqAuthenticated(r *http.Request) (s3Error APIErrorCode) {
+	if r == nil {
+		return ErrInternalError
+	}
+	payload, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return ErrInternalError
+	}
+	// Verify Content-Md5, if payload is set.
+	if r.Header.Get("Content-Md5") != "" {
+		if r.Header.Get("Content-Md5") != base64.StdEncoding.EncodeToString(sumMD5(payload)) {
+			return ErrBadDigest
+		}
+	}
+	// Populate back the payload.
+	r.Body = ioutil.NopCloser(bytes.NewReader(payload))
+	validateRegion := true // Validate region.
+	var sha256sum string
+	// Skips calculating sha256 on the payload on server,
+	// if client requested for it.
+	if skipContentSha256Cksum(r) {
+		sha256sum = unsignedPayload
+	} else {
+		sha256sum = hex.EncodeToString(sum256(payload))
+	}
+	if isRequestSignatureV4(r) {
+		return doesSignatureMatch(sha256sum, r, validateRegion)
+	} else if isRequestPresignedSignatureV4(r) {
+		return doesPresignedSignatureMatch(sha256sum, r, validateRegion)
+	}
+	return ErrAccessDenied
+}
+
+// checkAuth - checks for conditions satisfying the authorization of
+// the incoming request. Request should be either Presigned or Signed
+// in accordance with AWS S3 Signature V4 requirements. ErrAccessDenied
+// is returned for unhandled auth type. Once the auth type is indentified
+// request headers and body are used to calculate the signature validating
+// the client signature present in request.
+func checkAuth(r *http.Request) APIErrorCode {
+	aType := getRequestAuthType(r)
+	if aType != authTypePresigned && aType != authTypeSigned {
+		// For all unhandled auth types return error AccessDenied.
+		return ErrAccessDenied
+	}
+	// Validates the request for both Presigned and Signed.
+	return isReqAuthenticated(r)
+}
+
+// authHandler - handles all the incoming authorization headers and validates them if possible.
+type authHandler struct {
+	handler http.Handler
+}
+
+// setAuthHandler to validate authorization header for the incoming request.
+func setAuthHandler(h http.Handler) http.Handler {
+	return authHandler{h}
+}
+
+// List of all support S3 auth types.
+var supportedS3AuthTypes = []authType{
+	authTypeAnonymous,
+	authTypePresigned,
+	authTypeSigned,
+	authTypePostPolicy,
+	authTypeStreamingSigned,
+}
+
+// Validate if the authType is valid and supported.
+func isSupportedS3AuthType(aType authType) bool {
+	for _, a := range supportedS3AuthTypes {
+		if a == aType {
+			return true
+		}
+	}
+	return false
+}
+
+// handler for validating incoming authorization headers.
+func (a authHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	aType := getRequestAuthType(r)
+	if isSupportedS3AuthType(aType) {
+		// Let top level caller validate for anonymous and known signed requests.
+		a.handler.ServeHTTP(w, r)
+		return
+	} else if aType == authTypeJWT {
+		// Validate Authorization header if its valid for JWT request.
+		if !isJWTReqAuthenticated(r) {
+			w.WriteHeader(http.StatusUnauthorized)
+			return
+		}
+		a.handler.ServeHTTP(w, r)
+		return
+	}
+	writeErrorResponse(w, r, ErrSignatureVersionNotSupported, r.URL.Path)
+}