[internal-branch.go1.17-vendor] http2: accept zero-length block fragm…

…ents in HEADERS frames Fix a fencepost error which rejects HEADERS frames with neither payload nor padding, but accepts ones with padding and no payload. Updates golang/go#49077 Change-Id: Ic6ed65571366e86980a5ec69e7f9e6ab958f3b07 Reviewed-on: https://go-review.googlesource.com/c/net/+/344029 Trust: Damien Neil <[email protected]> Run-TryBot: Damien Neil <[email protected]> TryBot-Result: Go Bot <[email protected]> Reviewed-by: Brad Fitzpatrick <[email protected]> Reviewed-on: https://go-review.googlesource.com/c/net/+/357672 Reviewed-by: Dmitri Shuralyov <[email protected]>
fedosgad · Oct 29, 2021 · c302542 · c302542
1 parent 553fb77
commit c302542
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Showing 2 changed files with 18 additions and 1 deletion.
diff --git a/frame.go b/frame.go
@@ -1018,7 +1018,7 @@ func parseHeadersFrame(_ *frameCache, fh FrameHeader, p []byte) (_ Frame, err er
 			return nil, err
 		}
 	}
-	if len(p)-int(padLength) <= 0 {
+	if len(p)-int(padLength) < 0 {
 		return nil, streamError(fh.StreamID, ErrCodeProtocol)
 	}
 	hf.headerFragBuf = p[:len(p)-int(padLength)]

diff --git a/frame_test.go b/frame_test.go
@@ -312,6 +312,23 @@ func TestWriteHeaders(t *testing.T) {
 				headerFragBuf: []byte("abc"),
 			},
 		},
+		{
+			"zero length",
+			HeadersFrameParam{
+				StreamID: 42,
+				Priority: PriorityParam{},
+			},
+			"\x00\x00\x00\x01\x00\x00\x00\x00*",
+			&HeadersFrame{
+				FrameHeader: FrameHeader{
+					valid:    true,
+					StreamID: 42,
+					Type:     FrameHeaders,
+					Length:   0,
+				},
+				Priority: PriorityParam{},
+			},
+		},
 	}
 	for _, tt := range tests {
 		fr, buf := testFramer()