[#73] Uploader, downloader structures refactoring

Signed-off-by: Marina Biryukova <m.biryukova@yadro.com>

internal/handler/reader.go

@@ -0,0 +1,141 @@
+package handler
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net/http"
+	"path"
+	"strconv"
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/logs"
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/response"
+	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/utils"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
+	"github.com/valyala/fasthttp"
+	"go.uber.org/zap"
+)
+
+type readCloser struct {
+	io.Reader
+	io.Closer
+}
+
+// initializes io.Reader with the limited size and detects Content-Type from it.
+// Returns r's error directly. Also returns the processed data.
+func readContentType(maxSize uint64, rInit func(uint64) (io.Reader, error)) (string, []byte, error) {
+	if maxSize > sizeToDetectType {
+		maxSize = sizeToDetectType
+	}
+
+	buf := make([]byte, maxSize) // maybe sync-pool the slice?
+
+	r, err := rInit(maxSize)
+	if err != nil {
+		return "", nil, err
+	}
+
+	n, err := r.Read(buf)
+	if err != nil && err != io.EOF {
+		return "", nil, err
+	}
+
+	buf = buf[:n]
+
+	return http.DetectContentType(buf), buf, err // to not lose io.EOF
+}
+
+func (h *Handler) receiveFile(ctx context.Context, req request, objectAddress oid.Address) {
+	var (
+		err      error
+		dis      = "inline"
+		start    = time.Now()
+		filename string
+	)
+
+	var prm pool.PrmObjectGet
+	prm.SetAddress(objectAddress)
+	if btoken := bearerToken(ctx); btoken != nil {
+		prm.UseBearer(*btoken)
+	}
+
+	rObj, err := h.pool.GetObject(ctx, prm)
+	if err != nil {
+		req.handleFrostFSErr(err, start)
+		return
+	}
+
+	// we can't close reader in this function, so how to do it?
+
+	if req.Request.URI().QueryArgs().GetBool("download") {
+		dis = "attachment"
+	}
+
+	payloadSize := rObj.Header.PayloadSize()
+
+	req.Response.Header.Set(fasthttp.HeaderContentLength, strconv.FormatUint(payloadSize, 10))
+	var contentType string
+	for _, attr := range rObj.Header.Attributes() {
+		key := attr.Key()
+		val := attr.Value()
+		if !isValidToken(key) || !isValidValue(val) {
+			continue
+		}
+
+		key = utils.BackwardTransformIfSystem(key)
+
+		req.Response.Header.Set(utils.UserAttributeHeaderPrefix+key, val)
+		switch key {
+		case object.AttributeFileName:
+			filename = val
+		case object.AttributeTimestamp:
+			value, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				req.log.Info(logs.CouldntParseCreationDate,
+					zap.String("key", key),
+					zap.String("val", val),
+					zap.Error(err))
+				continue
+			}
+			req.Response.Header.Set(fasthttp.HeaderLastModified,
+				time.Unix(value, 0).UTC().Format(http.TimeFormat))
+		case object.AttributeContentType:
+			contentType = val
+		}
+	}
+
+	idsToResponse(&req.Response, &rObj.Header)
+
+	if len(contentType) == 0 {
+		// determine the Content-Type from the payload head
+		var payloadHead []byte
+
+		contentType, payloadHead, err = readContentType(payloadSize, func(uint64) (io.Reader, error) {
+			return rObj.Payload, nil
+		})
+		if err != nil && err != io.EOF {
+			req.log.Error(logs.CouldNotDetectContentTypeFromPayload, zap.Error(err))
+			response.Error(req.RequestCtx, "could not detect Content-Type from payload: "+err.Error(), fasthttp.StatusBadRequest)
+			return
+		}
+
+		// reset payload reader since a part of the data has been read
+		var headReader io.Reader = bytes.NewReader(payloadHead)
+
+		if err != io.EOF { // otherwise, we've already read full payload
+			headReader = io.MultiReader(headReader, rObj.Payload)
+		}
+
+		// note: we could do with io.Reader, but SetBodyStream below closes body stream
+		// if it implements io.Closer and that's useful for us.
+		rObj.Payload = readCloser{headReader, rObj.Payload}
+	}
+	req.SetContentType(contentType)
+
+	req.Response.Header.Set(fasthttp.HeaderContentDisposition, dis+"; filename="+path.Base(filename))
+
+	req.Response.SetBodyStream(rObj.Payload, int(payloadSize))
+}