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/api-headers.go

@@ -0,0 +1,89 @@
+/*
+ * Minio Cloud Storage, (C) 2015 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/rand"
+	"encoding/xml"
+	"net/http"
+	"runtime"
+	"strconv"
+)
+
+//// helpers
+
+// Static alphaNumeric table used for generating unique request ids
+var alphaNumericTable = []byte("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+// generateRequestID - Generate request id
+func generateRequestID() []byte {
+	alpha := make([]byte, 16)
+	rand.Read(alpha)
+	for i := 0; i < 16; i++ {
+		alpha[i] = alphaNumericTable[alpha[i]%byte(len(alphaNumericTable))]
+	}
+	return alpha
+}
+
+// Write http common headers
+func setCommonHeaders(w http.ResponseWriter) {
+	// Set unique request ID for each reply.
+	w.Header().Set("X-Amz-Request-Id", string(generateRequestID()))
+	w.Header().Set("Server", ("Minio/" + ReleaseTag + " (" + runtime.GOOS + "; " + runtime.GOARCH + ")"))
+	w.Header().Set("Accept-Ranges", "bytes")
+}
+
+// Encodes the response headers into XML format.
+func encodeResponse(response interface{}) []byte {
+	var bytesBuffer bytes.Buffer
+	bytesBuffer.WriteString(xml.Header)
+	e := xml.NewEncoder(&bytesBuffer)
+	e.Encode(response)
+	return bytesBuffer.Bytes()
+}
+
+// Write object header
+func setObjectHeaders(w http.ResponseWriter, objInfo ObjectInfo, contentRange *httpRange) {
+	// set common headers
+	setCommonHeaders(w)
+
+	// Set content length.
+	w.Header().Set("Content-Length", strconv.FormatInt(objInfo.Size, 10))
+
+	// Set last modified time.
+	lastModified := objInfo.ModTime.UTC().Format(http.TimeFormat)
+	w.Header().Set("Last-Modified", lastModified)
+
+	// Set Etag if available.
+	if objInfo.MD5Sum != "" {
+		w.Header().Set("ETag", "\""+objInfo.MD5Sum+"\"")
+	}
+
+	// Set all other user defined metadata.
+	for k, v := range objInfo.UserDefined {
+		w.Header().Set(k, v)
+	}
+
+	// for providing ranged content
+	if contentRange != nil && contentRange.offsetBegin > -1 {
+		// Override content-length
+		w.Header().Set("Content-Length", strconv.FormatInt(contentRange.getLength(), 10))
+		w.Header().Set("Content-Range", contentRange.String())
+		w.WriteHeader(http.StatusPartialContent)
+	}
+}