Fixes after review

- It's confusing. If there is no difference, I suggest having the route named after the protocol verb or resulting handler. So it should be either post or upload.
- Don't you find that it would be more understandable without else ifs?
- Why do we need a temporary file here?
- etc

Signed-off-by: Evgeniy Kulikov <kim@nspcc.ru>

app.go

@@ -181,8 +181,8 @@ func (a *app) Serve(ctx context.Context) {
 	r := router.New()
 	r.RedirectTrailingSlash = true
 
-	a.log.Info("enabled /put/{cid}")
-	r.POST("/put/{cid}", a.upload)
+	a.log.Info("enabled /upload/{cid}")
+	r.POST("/upload/{cid}", a.upload)
 
 	a.log.Info("enabled /get/{cid}/{oid}")
 	r.GET("/get/{cid}/{oid}", a.byAddress)

filter.go

@@ -61,13 +61,24 @@ func (h *headerFilter) Filter(header *fasthttp.RequestHeader) map[string]string
 	prefix := []byte(userAttributeHeaderPrefix)
 
 	header.VisitAll(func(key, val []byte) {
+		// checks that key and val not empty
 		if len(key) == 0 || len(val) == 0 {
 			return
-		} else if !bytes.HasPrefix(key, prefix) {
+		}
+
+		// checks that key has attribute prefix
+		if !bytes.HasPrefix(key, prefix) {
 			return
-		} else if key = bytes.TrimPrefix(key, prefix); len(key) == 0 {
+		}
+
+		// checks that after removing attribute prefix we had not empty key
+		if key = bytes.TrimPrefix(key, prefix); len(key) == 0 {
 			return
-		} else if name, ok := h.mapping[string(key)]; ok {
+		}
+
+		// checks mapping table and if we found record store it
+		// at resulting hashmap
+		if name, ok := h.mapping[string(key)]; ok {
 			result[name] = string(val)
 
 			h.logger.Debug("add attribute to result object",
@@ -77,6 +88,7 @@ func (h *headerFilter) Filter(header *fasthttp.RequestHeader) map[string]string
 			return
 		}
 
+		// otherwise inform that attribute will be ignored
 		h.logger.Debug("ignore attribute",
 			zap.String("key", string(key)),
 			zap.String("val", string(val)))

upload.go

@@ -3,9 +3,7 @@ package main
 import (
 	"encoding/json"
 	"io"
-	"io/ioutil"
 	"mime/multipart"
-	"os"
 	"strconv"
 	"time"
 
@@ -40,7 +38,7 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 	var (
 		err     error
 		name    string
-		tmp     *os.File
+		tmp     io.Reader
 		addr    *object.Address
 		form    *multipart.Form
 		cid     = container.NewID()
@@ -55,50 +53,51 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 		return
 	}
 
-	if tmp, err = ioutil.TempFile("", "http-gate-upload-*"); err != nil {
-		log.Error("could not prepare temporary file", zap.Error(err))
-		c.Error("could not prepare temporary file", fasthttp.StatusBadRequest)
-		return
-	}
-
 	defer func() {
-		tmpName := tmp.Name()
-
-		log.Debug("close temporary file", zap.Error(tmp.Close()))
-		log.Debug("remove temporary file", zap.Error(os.RemoveAll(tmpName)))
+		// if temporary reader can be closed - close it
+		if closer := tmp.(io.Closer); closer != nil {
+			log.Debug("close temporary multipart/form file", zap.Error(closer.Close()))
+		}
 
 		if form == nil {
 			return
 		}
 
-		log.Debug("cleanup multipart form", zap.Error(form.RemoveAll()))
+		log.Debug("cleanup multipart/form", zap.Error(form.RemoveAll()))
 	}()
 
+	// tries to receive multipart/form or throw error
 	if form, err = c.MultipartForm(); err != nil {
-		log.Error("could not receive multipart form", zap.Error(err))
-		c.Error("could not receive multipart form: "+err.Error(), fasthttp.StatusBadRequest)
+		log.Error("could not receive multipart/form", zap.Error(err))
+		c.Error("could not receive multipart/form: "+err.Error(), fasthttp.StatusBadRequest)
 
 		return
-	} else if ln := len(form.File); ln != 1 {
-		log.Error("received multipart form with more then one file", zap.Int("count", ln))
-		c.Error("received multipart form with more then one file", fasthttp.StatusBadRequest)
+	}
+
+	// checks that received multipart/form contains only one `file` per request
+	if ln := len(form.File); ln != 1 {
+		log.Error("received multipart/form with more then one file", zap.Int("count", ln))
+		c.Error("received multipart/form with more then one file", fasthttp.StatusBadRequest)
 
 		return
 	}
 
 	for _, file := range form.File {
+		// because multipart/form can contains multiple FileHeader records
+		// we should check that we have only one per request or throw error
 		if ln := len(file); ln != 1 {
-			log.Error("received multipart form file should contains one record", zap.Int("count", ln))
-			c.Error("received multipart form file should contains one record", fasthttp.StatusBadRequest)
+			log.Error("received multipart/form file should contains one record", zap.Int("count", ln))
+			c.Error("received multipart/form file should contains one record", fasthttp.StatusBadRequest)
 
 			return
 		}
 
 		name = file[0].Filename
 
-		if err = fasthttp.SaveMultipartFile(file[0], tmp.Name()); err != nil {
-			log.Error("could not store uploaded file into temporary", zap.Error(err))
-			c.Error("could not store uploaded file into temporary", fasthttp.StatusBadRequest)
+		// opens multipart/form file to work within or throw error
+		if tmp, err = file[0].Open(); err != nil {
+			log.Error("could not prepare uploaded file", zap.Error(err))
+			c.Error("could not prepare uploaded file", fasthttp.StatusBadRequest)
 
 			return
 		}
@@ -107,6 +106,7 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 	filtered := a.hdr.Filter(&c.Request.Header)
 	attributes := make([]*object.Attribute, 0, len(filtered))
 
+	// prepares attributes from filtered headers
 	for key, val := range filtered {
 		attribute := object.NewAttribute()
 		attribute.SetKey(key)
@@ -115,7 +115,7 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 		attributes = append(attributes, attribute)
 	}
 
-	// Attribute FileName wasn't set from header
+	// sets FileName attribute if it wasn't set from header
 	if _, ok := filtered[object.AttributeFileName]; ok {
 		filename := object.NewAttribute()
 		filename.SetKey(object.AttributeFileName)
@@ -124,7 +124,7 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 		attributes = append(attributes, filename)
 	}
 
-	// Attribute Timestamp wasn't set from header and enabled by settings
+	// sets Timestamp attribute if it wasn't set from header and enabled by settings
 	if _, ok := filtered[object.AttributeTimestamp]; ok && a.enableDefaultTimestamp {
 		timestamp := object.NewAttribute()
 		timestamp.SetKey(object.AttributeTimestamp)
@@ -133,23 +133,29 @@ func (a *app) upload(c *fasthttp.RequestCtx) {
 		attributes = append(attributes, timestamp)
 	}
 
+	// prepares new object and fill it
 	raw := object.NewRaw()
 	raw.SetContainerID(cid)
 	raw.SetOwnerID(a.cli.Owner()) // should be various: from sdk / BearerToken
 	raw.SetAttributes(attributes...)
 
+	// tries to put file into NeoFS or throw error
 	if addr, err = a.cli.Object().Put(c, raw.Object(), sdk.WithPutReader(tmp)); err != nil {
 		log.Error("could not store file in NeoFS", zap.Error(err))
 		c.Error("could not store file in NeoFS", fasthttp.StatusBadRequest)
 
 		return
-	} else if err = newPutResponse(addr).Encode(c); err != nil {
+	}
+
+	// tries to return response, otherwise, if something went wrong throw error
+	if err = newPutResponse(addr).Encode(c); err != nil {
 		log.Error("could not prepare response", zap.Error(err))
 		c.Error("could not prepare response", fasthttp.StatusBadRequest)
 
 		return
 	}
 
+	// reports status code and content type
 	c.Response.SetStatusCode(fasthttp.StatusOK)
 	c.Response.Header.SetContentType(jsonHeader)
 }