swarm/api/http: refactored http package (#17309)

swarm/api/http/response.go

@@ -0,0 +1,139 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package http
+
+import (
+	"encoding/json"
+	"fmt"
+	"html/template"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/swarm/api"
+)
+
+//metrics variables
+var (
+	htmlCounter      = metrics.NewRegisteredCounter("api.http.errorpage.html.count", nil)
+	jsonCounter      = metrics.NewRegisteredCounter("api.http.errorpage.json.count", nil)
+	plaintextCounter = metrics.NewRegisteredCounter("api.http.errorpage.plaintext.count", nil)
+)
+
+//parameters needed for formatting the correct HTML page
+type ResponseParams struct {
+	Msg       template.HTML
+	Code      int
+	Timestamp string
+	template  *template.Template
+	Details   template.HTML
+}
+
+//ShowMultipeChoices is used when a user requests a resource in a manifest which results
+//in ambiguous results. It returns a HTML page with clickable links of each of the entry
+//in the manifest which fits the request URI ambiguity.
+//For example, if the user requests bzz:/<hash>/read and that manifest contains entries
+//"readme.md" and "readinglist.txt", a HTML page is returned with this two links.
+//This only applies if the manifest has no default entry
+func ShowMultipleChoices(w http.ResponseWriter, r *http.Request, list api.ManifestList) {
+	log.Debug("ShowMultipleChoices", "ruid", GetRUID(r.Context()), "uri", GetURI(r.Context()))
+	msg := ""
+	if list.Entries == nil {
+		RespondError(w, r, "Could not resolve", http.StatusInternalServerError)
+		return
+	}
+	requestUri := strings.TrimPrefix(r.RequestURI, "/")
+
+	uri, err := api.Parse(requestUri)
+	if err != nil {
+		RespondError(w, r, "Bad Request", http.StatusBadRequest)
+	}
+
+	uri.Scheme = "bzz-list"
+	//request the same url just with bzz-list
+	msg += fmt.Sprintf("Disambiguation:<br/>Your request may refer to multiple choices.<br/>Click <a class=\"orange\" href='"+"/"+uri.String()+"'>here</a> if your browser does not redirect you within 5 seconds.<script>setTimeout(\"location.href='%s';\",5000);</script><br/>", "/"+uri.String())
+	RespondTemplate(w, r, "error", msg, http.StatusMultipleChoices)
+}
+
+func RespondTemplate(w http.ResponseWriter, r *http.Request, templateName, msg string, code int) {
+	log.Debug("RespondTemplate", "ruid", GetRUID(r.Context()), "uri", GetURI(r.Context()))
+	respond(w, r, &ResponseParams{
+		Code:      code,
+		Msg:       template.HTML(msg),
+		Timestamp: time.Now().Format(time.RFC1123),
+		template:  TemplatesMap[templateName],
+	})
+}
+
+func RespondError(w http.ResponseWriter, r *http.Request, msg string, code int) {
+	log.Debug("RespondError", "ruid", GetRUID(r.Context()), "uri", GetURI(r.Context()))
+	RespondTemplate(w, r, "error", msg, code)
+}
+
+//evaluate if client accepts html or json response
+func respond(w http.ResponseWriter, r *http.Request, params *ResponseParams) {
+	w.WriteHeader(params.Code)
+
+	if params.Code >= 400 {
+		w.Header().Del("Cache-Control") //avoid sending cache headers for errors!
+		w.Header().Del("ETag")
+	}
+
+	acceptHeader := r.Header.Get("Accept")
+	// this cannot be in a switch form since an Accept header can be in the form of "Accept: */*, text/html, application/xhtml+xml, application/xml;q=0.9, */*;q=0.8"
+	if strings.Contains(acceptHeader, "application/json") {
+		if err := respondJSON(w, r, params); err != nil {
+			RespondError(w, r, "Internal server error", http.StatusInternalServerError)
+		}
+	} else if strings.Contains(acceptHeader, "text/html") {
+		respondHTML(w, r, params)
+	} else {
+		respondPlaintext(w, r, params) //returns nice errors for curl
+	}
+}
+
+//return a HTML page
+func respondHTML(w http.ResponseWriter, r *http.Request, params *ResponseParams) {
+	htmlCounter.Inc(1)
+	log.Debug("respondHTML", "ruid", GetRUID(r.Context()))
+	err := params.template.Execute(w, params)
+	if err != nil {
+		log.Error(err.Error())
+	}
+}
+
+//return JSON
+func respondJSON(w http.ResponseWriter, r *http.Request, params *ResponseParams) error {
+	jsonCounter.Inc(1)
+	log.Debug("respondJSON", "ruid", GetRUID(r.Context()))
+	w.Header().Set("Content-Type", "application/json")
+	return json.NewEncoder(w).Encode(params)
+}
+
+//return plaintext
+func respondPlaintext(w http.ResponseWriter, r *http.Request, params *ResponseParams) error {
+	plaintextCounter.Inc(1)
+	log.Debug("respondPlaintext", "ruid", GetRUID(r.Context()))
+	w.Header().Set("Content-Type", "text/plain")
+	strToWrite := "Code: " + fmt.Sprintf("%d", params.Code) + "\n"
+	strToWrite += "Message: " + string(params.Msg) + "\n"
+	strToWrite += "Timestamp: " + params.Timestamp + "\n"
+	_, err := w.Write([]byte(strToWrite))
+	return err
+}