net/http: accept Content-Range for entire file

Fixes a bug reported privately.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13846043

src/pkg/net/http/fs.go

@@ -173,7 +173,7 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 			Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
 			return
 		}
-		if sumRangesSize(ranges) >= size {
+		if sumRangesSize(ranges) > size {
 			// The total number of bytes in all the ranges
 			// is larger than the size of the file by
 			// itself, so this is probably an attack, or a

src/pkg/net/http/fs_test.go

@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -36,6 +37,8 @@ type wantRange struct {
 	start, end int64 // range [start,end)
 }
 
+var itoa = strconv.Itoa
+
 var ServeFileRangeTests = []struct {
 	r      string
 	code   int
@@ -50,7 +53,11 @@ var ServeFileRangeTests = []struct {
 	{r: "bytes=0-0,-2", code: StatusPartialContent, ranges: []wantRange{{0, 1}, {testFileLen - 2, testFileLen}}},
 	{r: "bytes=0-1,5-8", code: StatusPartialContent, ranges: []wantRange{{0, 2}, {5, 9}}},
 	{r: "bytes=0-1,5-", code: StatusPartialContent, ranges: []wantRange{{0, 2}, {5, testFileLen}}},
+	{r: "bytes=5-1000", code: StatusPartialContent, ranges: []wantRange{{5, testFileLen}}},
 	{r: "bytes=0-,1-,2-,3-,4-", code: StatusOK}, // ignore wasteful range request
+	{r: "bytes=0-" + itoa(testFileLen-2), code: StatusPartialContent, ranges: []wantRange{{0, testFileLen - 1}}},
+	{r: "bytes=0-" + itoa(testFileLen-1), code: StatusPartialContent, ranges: []wantRange{{0, testFileLen}}},
+	{r: "bytes=0-" + itoa(testFileLen), code: StatusPartialContent, ranges: []wantRange{{0, testFileLen}}},
 }
 
 func TestServeFile(t *testing.T) {