[release-branch.go1.17] net/http: don't strip whitespace from Transfer-Encoding headers

Do not accept "Transfer-Encoding: \rchunked" as a valid TE header
setting chunked encoding.

Thanks to Zeyu Zhang (https://www.zeyu2001.com/) for identifying
the issue.

For #53188
For CVE-2022-1705
Fixes #53432

Change-Id: I1a16631425159267f2eca68056b057192a7edf6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/409874
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit e5017a93fc)
Reviewed-on: https://go-review.googlesource.com/c/go/+/415217
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/net/http/serve_test.go

@@ -6189,6 +6189,7 @@ func TestUnsupportedTransferEncodingsReturn501(t *testing.T) {
 		"fugazi",
 		"foo-bar",
 		"unknown",
+		"\rchunked",
 	}
 
 	for _, badTE := range unsupportedTEs {

src/net/http/transfer.go

@@ -639,7 +639,7 @@ func (t *transferReader) parseTransferEncoding() error {
 	if len(raw) != 1 {
 		return &unsupportedTEError{fmt.Sprintf("too many transfer encodings: %q", raw)}
 	}
-	if !ascii.EqualFold(textproto.TrimString(raw[0]), "chunked") {
+	if !ascii.EqualFold(raw[0], "chunked") {
 		return &unsupportedTEError{fmt.Sprintf("unsupported transfer encoding: %q", raw[0])}
 	}