1 files changed, 52 insertions, 0 deletions
diff --git a/src/cmd/go/http.go b/src/cmd/go/http.go
index 8d9b2a165..6de9a3e1e 100644
--- a/src/cmd/go/http.go
+++ b/src/cmd/go/http.go
@@ -13,8 +13,11 @@ package main
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
+	"log"
 	"net/http"
+	"net/url"
 )
 
 // httpGET returns the data from an HTTP GET request for the given URL.
@@ -33,3 +36,52 @@ func httpGET(url string) ([]byte, error) {
 	}
 	return b, nil
 }
+
+// httpClient is the default HTTP client, but a variable so it can be
+// changed by tests, without modifying http.DefaultClient.
+var httpClient = http.DefaultClient
+
+// httpsOrHTTP returns the body of either the importPath's
+// https resource or, if unavailable, the http resource.
+func httpsOrHTTP(importPath string) (urlStr string, body io.ReadCloser, err error) {
+	fetch := func(scheme string) (urlStr string, res *http.Response, err error) {
+		u, err := url.Parse(scheme + "://" + importPath)
+		if err != nil {
+			return "", nil, err
+		}
+		u.RawQuery = "go-get=1"
+		urlStr = u.String()
+		if buildV {
+			log.Printf("Fetching %s", urlStr)
+		}
+		res, err = httpClient.Get(urlStr)
+		return
+	}
+	closeBody := func(res *http.Response) {
+		if res != nil {
+			res.Body.Close()
+		}
+	}
+	urlStr, res, err := fetch("https")
+	if err != nil || res.StatusCode != 200 {
+		if buildV {
+			if err != nil {
+				log.Printf("https fetch failed.")
+			} else {
+				log.Printf("ignoring https fetch with status code %d", res.StatusCode)
+			}
+		}
+		closeBody(res)
+		urlStr, res, err = fetch("http")
+	}
+	if err != nil {
+		closeBody(res)
+		return "", nil, err
+	}
+	// Note: accepting a non-200 OK here, so people can serve a
+	// meta import in their http 404 page.
+	if buildV {
+		log.Printf("Parsing meta tags from %s (status code %d)", urlStr, res.StatusCode)
+	}
+	return urlStr, res.Body, nil
+}