Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

pkg/request/utils.go

@@ -0,0 +1,62 @@
+package request
+
+import (
+	"io"
+	"net/http"
+	"strconv"
+)
+
+var contentLengthHeaders = []string{
+	"Content-Length",
+	"X-Expected-Entity-Length", // DavFS on MacOS
+}
+
+// BlackHole 将客户端发来的数据放入黑洞
+func BlackHole(r io.Reader) {
+	io.Copy(io.Discard, r)
+}
+
+// SniffContentLength tries to get the content length from the request. It also returns
+// a reader that will limit to the sniffed content length.
+func SniffContentLength(r *http.Request) (LimitReaderCloser, int64, error) {
+	for _, header := range contentLengthHeaders {
+		if length := r.Header.Get(header); length != "" {
+			res, err := strconv.ParseInt(length, 10, 64)
+			if err != nil {
+				return nil, 0, err
+			}
+
+			return newLimitReaderCloser(r.Body, res), res, nil
+		}
+	}
+	return newLimitReaderCloser(r.Body, 0), 0, nil
+}
+
+type LimitReaderCloser interface {
+	io.Reader
+	io.Closer
+	Count() int64
+}
+
+type limitReaderCloser struct {
+	io.Reader
+	io.Closer
+	read int64
+}
+
+func newLimitReaderCloser(r io.ReadCloser, limit int64) LimitReaderCloser {
+	return &limitReaderCloser{
+		Reader: io.LimitReader(r, limit),
+		Closer: r,
+	}
+}
+
+func (l *limitReaderCloser) Read(p []byte) (n int, err error) {
+	n, err = l.Reader.Read(p)
+	l.read += int64(n)
+	return n, err
+}
+
+func (l *limitReaderCloser) Count() int64 {
+	return l.read
+}