lib/http: Move HTTP object serialization logic to lib/http

lib/http/serve/serve.go

@@ -0,0 +1,91 @@
+// Package serve deals with serving objects over HTTP
+package serve
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"path"
+	"strconv"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/accounting"
+)
+
+// Object serves an fs.Object via HEAD or GET
+func Object(w http.ResponseWriter, r *http.Request, o fs.Object) {
+	if r.Method != "HEAD" && r.Method != "GET" {
+		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+		return
+	}
+
+	// Show that we accept ranges
+	w.Header().Set("Accept-Ranges", "bytes")
+
+	// Set content length since we know how long the object is
+	if o.Size() >= 0 {
+		w.Header().Set("Content-Length", strconv.FormatInt(o.Size(), 10))
+	}
+
+	// Set content type
+	mimeType := fs.MimeType(r.Context(), o)
+	if mimeType == "application/octet-stream" && path.Ext(o.Remote()) == "" {
+		// Leave header blank so http server guesses
+	} else {
+		w.Header().Set("Content-Type", mimeType)
+	}
+
+	if r.Method == "HEAD" {
+		return
+	}
+
+	// Decode Range request if present
+	code := http.StatusOK
+	size := o.Size()
+	var options []fs.OpenOption
+	if rangeRequest := r.Header.Get("Range"); rangeRequest != "" {
+		//fs.Debugf(nil, "Range: request %q", rangeRequest)
+		option, err := fs.ParseRangeOption(rangeRequest)
+		if err != nil {
+			fs.Debugf(o, "Get request parse range request error: %v", err)
+			http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+			return
+		}
+		options = append(options, option)
+		offset, limit := option.Decode(o.Size())
+		end := o.Size() // exclusive
+		if limit >= 0 {
+			end = offset + limit
+		}
+		if end > o.Size() {
+			end = o.Size()
+		}
+		size = end - offset
+		// fs.Debugf(nil, "Range: offset=%d, limit=%d, end=%d, size=%d (object size %d)", offset, limit, end, size, o.Size())
+		// Content-Range: bytes 0-1023/146515
+		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", offset, end-1, o.Size()))
+		// fs.Debugf(nil, "Range: Content-Range: %q", w.Header().Get("Content-Range"))
+		code = http.StatusPartialContent
+	}
+	w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
+
+	file, err := o.Open(r.Context(), options...)
+	if err != nil {
+		fs.Debugf(o, "Get request open error: %v", err)
+		http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+		return
+	}
+	tr := accounting.Stats(r.Context()).NewTransfer(o)
+	defer func() {
+		tr.Done(r.Context(), err)
+	}()
+	in := tr.Account(r.Context(), file) // account the transfer (no buffering)
+
+	w.WriteHeader(code)
+
+	n, err := io.Copy(w, in)
+	if err != nil {
+		fs.Errorf(o, "Didn't finish writing GET request (wrote %d/%d bytes): %v", n, size, err)
+		return
+	}
+}