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/signature-v4-utils.go

@@ -0,0 +1,158 @@
+/*
+ * 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 (
+	"crypto/hmac"
+	"encoding/hex"
+	"github.com/minio/sha256-simd"
+	"net/http"
+	"regexp"
+	"strings"
+	"unicode/utf8"
+)
+
+// http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD" indicates that the
+// client did not calculate sha256 of the payload.
+const unsignedPayload = "UNSIGNED-PAYLOAD"
+
+// http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD" indicates that the
+// client did not calculate sha256 of the payload. Hence we skip calculating sha256.
+// We also skip calculating sha256 for presigned requests without "x-amz-content-sha256" header.
+func skipContentSha256Cksum(r *http.Request) bool {
+	contentSha256 := r.Header.Get("X-Amz-Content-Sha256")
+	return isRequestUnsignedPayload(r) || (isRequestPresignedSignatureV4(r) && contentSha256 == "")
+}
+
+// isValidRegion - verify if incoming region value is valid with configured Region.
+func isValidRegion(reqRegion string, confRegion string) bool {
+	if confRegion == "" || confRegion == "US" {
+		confRegion = "us-east-1"
+	}
+	// Some older s3 clients set region as "US" instead of
+	// "us-east-1", handle it.
+	if reqRegion == "US" {
+		reqRegion = "us-east-1"
+	}
+	return reqRegion == confRegion
+}
+
+// sumHMAC calculate hmac between two input byte array.
+func sumHMAC(key []byte, data []byte) []byte {
+	hash := hmac.New(sha256.New, key)
+	hash.Write(data)
+	return hash.Sum(nil)
+}
+
+// Reserved string regexp.
+var reservedNames = regexp.MustCompile("^[a-zA-Z0-9-_.~/]+$")
+
+// getURLEncodedName encode the strings from UTF-8 byte representations to HTML hex escape sequences
+//
+// This is necessary since regular url.Parse() and url.Encode() functions do not support UTF-8
+// non english characters cannot be parsed due to the nature in which url.Encode() is written
+//
+// This function on the other hand is a direct replacement for url.Encode() technique to support
+// pretty much every UTF-8 character.
+func getURLEncodedName(name string) string {
+	// if object matches reserved string, no need to encode them
+	if reservedNames.MatchString(name) {
+		return name
+	}
+	var encodedName string
+	for _, s := range name {
+		if 'A' <= s && s <= 'Z' || 'a' <= s && s <= 'z' || '0' <= s && s <= '9' { // §2.3 Unreserved characters (mark)
+			encodedName = encodedName + string(s)
+			continue
+		}
+		switch s {
+		case '-', '_', '.', '~', '/': // §2.3 Unreserved characters (mark)
+			encodedName = encodedName + string(s)
+			continue
+		default:
+			len := utf8.RuneLen(s)
+			if len < 0 {
+				return name
+			}
+			u := make([]byte, len)
+			utf8.EncodeRune(u, s)
+			for _, r := range u {
+				hex := hex.EncodeToString([]byte{r})
+				encodedName = encodedName + "%" + strings.ToUpper(hex)
+			}
+		}
+	}
+	return encodedName
+}
+
+// find whether "host" is part of list of signed headers.
+func findHost(signedHeaders []string) APIErrorCode {
+	for _, header := range signedHeaders {
+		if header == "host" {
+			return ErrNone
+		}
+	}
+	return ErrUnsignedHeaders
+}
+
+// extractSignedHeaders extract signed headers from Authorization header
+func extractSignedHeaders(signedHeaders []string, reqHeaders http.Header) (http.Header, APIErrorCode) {
+	errCode := findHost(signedHeaders)
+	if errCode != ErrNone {
+		return nil, errCode
+	}
+	extractedSignedHeaders := make(http.Header)
+	for _, header := range signedHeaders {
+		// `host` will not be found in the headers, can be found in r.Host.
+		// but its alway necessary that the list of signed headers containing host in it.
+
+		val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
+		if !ok {
+			// Golang http server strips off 'Expect' header, if the
+			// client sent this as part of signed headers we need to
+			// handle otherwise we would see a signature mismatch.
+			// `aws-cli` sets this as part of signed headers.
+			//
+			// According to
+			// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
+			// Expect header is always of form:
+			//
+			//   Expect       =  "Expect" ":" 1#expectation
+			//   expectation  =  "100-continue" | expectation-extension
+			//
+			// So it safe to assume that '100-continue' is what would
+			// be sent, for the time being keep this work around.
+			// Adding a *TODO* to remove this later when Golang server
+			// doesn't filter out the 'Expect' header.
+			if header == "expect" {
+				extractedSignedHeaders[header] = []string{"100-continue"}
+				continue
+			}
+			// the "host" field will not be found in the header map, it can be found in req.Host.
+			// but its necessary to make sure that the "host" field exists in the list of signed parameters,
+			// the check is done above.
+			if header == "host" {
+				continue
+			}
+			// If not found continue, we will stop here.
+			return nil, ErrUnsignedHeaders
+		}
+		extractedSignedHeaders[header] = val
+	}
+
+	return extractedSignedHeaders, ErrNone
+}