From d08b92a0dddd6408abbb261c3cd240464d59cc88 Mon Sep 17 00:00:00 2001
From: kun <oiooj@qq.com>
Date: Tue, 18 Feb 2020 21:56:04 +0800
Subject: [PATCH] support sumdb

---
 proxy/router.go  |  7 +++++
 proxy/server.go  |  9 +++++++
 sumdb/handler.go | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)
 create mode 100644 sumdb/handler.go

diff --git a/proxy/router.go b/proxy/router.go
index 33a745e..c5d0caa 100644
--- a/proxy/router.go
+++ b/proxy/router.go
@@ -16,6 +16,7 @@ import (
 	"time"
 
 	"github.com/goproxyio/goproxy/v2/renameio"
+	"github.com/goproxyio/goproxy/v2/sumdb"
 )
 
 const ListExpire = 5 * time.Minute
@@ -110,6 +111,12 @@ func (rt *Router) Direct(path string) bool {
 }
 
 func (rt *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// sumdb handler
+	if strings.HasPrefix(r.URL.Path, "/sumdb/") {
+		sumdb.Handler(w, r)
+		return
+	}
+
 	if rt.proxy == nil || rt.Direct(strings.TrimPrefix(r.URL.Path, "/")) {
 		log.Printf("------ --- %s [direct]\n", r.URL)
 		rt.srv.ServeHTTP(w, r)
diff --git a/proxy/server.go b/proxy/server.go
index 72198ad..8c7c3e2 100644
--- a/proxy/server.go
+++ b/proxy/server.go
@@ -15,6 +15,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/goproxyio/goproxy/v2/sumdb"
+
 	"golang.org/x/mod/module"
 )
 
@@ -119,6 +121,13 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
+
+	// sumdb handler
+	if strings.HasPrefix(r.URL.Path, "/sumdb/") {
+		sumdb.Handler(w, r)
+		return
+	}
+
 	i := strings.Index(r.URL.Path, "/@")
 	if i < 0 {
 		http.Error(w, "no such path", http.StatusNotFound)
diff --git a/sumdb/handler.go b/sumdb/handler.go
new file mode 100644
index 0000000..1721d66
--- /dev/null
+++ b/sumdb/handler.go
@@ -0,0 +1,68 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+// Package proxy implements the HTTP protocols for serving a Go module proxy.
+package sumdb
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+var enableGoogleSumDB bool
+var supportedSumDB = []string{
+	"sum.golang.org",
+	"gosum.io",
+}
+
+func init() {
+	go func() {
+		p := "https://sum.google.com"
+		_, err := http.Get(p)
+		if err == nil {
+			enableGoogleSumDB = true
+		}
+	}()
+}
+
+//Handler handles sumdb request
+func Handler(w http.ResponseWriter, r *http.Request) {
+	if !enableGoogleSumDB {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	for _, supported := range supportedSumDB {
+		uri := fmt.Sprintf("/sumdb/%s/supported", supported)
+		if r.URL.Path == uri {
+			w.WriteHeader(http.StatusOK)
+			return
+		}
+	}
+
+	p := "https://" + strings.TrimPrefix(r.URL.Path, "/sumdb/")
+	_, err := url.Parse(p)
+	if err != nil {
+		w.WriteHeader(http.StatusGone)
+		fmt.Fprintf(w, err.Error())
+		return
+	}
+
+	resp, err := http.Get(p)
+	if err != nil {
+		w.WriteHeader(http.StatusGone)
+		fmt.Fprintf(w, err.Error())
+		return
+	}
+	defer resp.Body.Close()
+	w.WriteHeader(resp.StatusCode)
+	if _, err := io.Copy(w, resp.Body); err != nil {
+		fmt.Fprintf(w, err.Error())
+		return
+	}
+
+	return
+}