net/http: fix panic with If-None-Match value in http.ServeContent

Fixes #39817 Change-Id: I79f2ad7c836a8a46569f603aca583fdd526d22dc GitHub-Last-Rev: 5b88aad GitHub-Pull-Request: #39821 Reviewed-on: https://go-review.googlesource.com/c/go/+/239699 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
golang · Jun 29, 2020 · ce81a8f · ce81a8f
1 parent 152ffca
commit ce81a8f
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diff --git a/src/net/http/fs.go b/src/net/http/fs.go
@@ -413,6 +413,7 @@ func checkIfNoneMatch(w ResponseWriter, r *Request) condResult {
 		}
 		if buf[0] == ',' {
 			buf = buf[1:]
+			continue
 		}
 		if buf[0] == '*' {
 			return condFalse

diff --git a/src/net/http/fs_test.go b/src/net/http/fs_test.go
@@ -849,6 +849,15 @@ func TestServeContent(t *testing.T) {
 			wantStatus:      200,
 			wantContentType: "text/css; charset=utf-8",
 		},
+		"if_none_match_malformed": {
+			file:      "testdata/style.css",
+			serveETag: `"foo"`,
+			reqHeader: map[string]string{
+				"If-None-Match": `,`,
+			},
+			wantStatus:      200,
+			wantContentType: "text/css; charset=utf-8",
+		},
 		"range_good": {
 			file:      "testdata/style.css",
 			serveETag: `"A"`,