package/go: add Debian backport of upstream security fix

Fixes the following security vulnerability:

- CVE-2019-16276: Go before 1.12.10 and 1.13.x before 1.13.1 allow HTTP
  Request Smuggling.
  https://github.com/golang/go/issues/34540

Upstream has not provided a go 1.11.x release with a fix for this, so
instead include the Debian backport of the upstream security fix from:

https://sources.debian.org/src/golang-1.11/1.11.6-1+deb10u2/debian/patches/0007-Fix-CVE-2019-16276.patch/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/go/0002-Fix-CVE-2019-16276.patch

@@ -0,0 +1,123 @@
+From: "Dr. Tobias Quathamer" <toddy@debian.org>
+Date: Thu, 26 Sep 2019 11:46:46 +0200
+Subject: Fix CVE-2019-16276
+
+Cherry-picked from upstream:
+https://github.com/golang/go/commit/6e6f4aaf70c8b1cc81e65a26332aa9409de03ad8
+
+[Upstream: https://sources.debian.org/src/golang-1.11/1.11.6-1+deb10u2/debian/patches/0007-Fix-CVE-2019-16276.patch]
+Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
+---
+ src/net/http/serve_test.go       |  4 ++++
+ src/net/http/transport_test.go   | 27 +++++++++++++++++++++++++++
+ src/net/textproto/reader.go      | 10 ++--------
+ src/net/textproto/reader_test.go | 13 ++++++-------
+ 4 files changed, 39 insertions(+), 15 deletions(-)
+
+diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
+index a438541..18edf98 100644
+--- a/src/net/http/serve_test.go
++++ b/src/net/http/serve_test.go
+@@ -4725,6 +4725,10 @@ func TestServerValidatesHeaders(t *testing.T) {
+ 		{"foo\xffbar: foo\r\n", 400},                         // binary in header
+ 		{"foo\x00bar: foo\r\n", 400},                         // binary in header
+ 		{"Foo: " + strings.Repeat("x", 1<<21) + "\r\n", 431}, // header too large
++		// Spaces between the header key and colon are not allowed.
++		// See RFC 7230, Section 3.2.4.
++		{"Foo : bar\r\n", 400},
++		{"Foo\t: bar\r\n", 400},
+ 
+ 		{"foo: foo foo\r\n", 200},    // LWS space is okay
+ 		{"foo: foo\tfoo\r\n", 200},   // LWS tab is okay
+diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
+index b2036df..dff940e 100644
+--- a/src/net/http/transport_test.go
++++ b/src/net/http/transport_test.go
+@@ -4838,3 +4838,30 @@ func TestClientTimeoutKillsConn_AfterHeaders(t *testing.T) {
+ 		t.Fatal("timeout")
+ 	}
+ }
++
++func TestInvalidHeaderResponse(t *testing.T) {
++	setParallel(t)
++	defer afterTest(t)
++	cst := newClientServerTest(t, h1Mode, HandlerFunc(func(w ResponseWriter, r *Request) {
++		conn, buf, _ := w.(Hijacker).Hijack()
++		buf.Write([]byte("HTTP/1.1 200 OK\r\n" +
++			"Date: Wed, 30 Aug 2017 19:09:27 GMT\r\n" +
++			"Content-Type: text/html; charset=utf-8\r\n" +
++			"Content-Length: 0\r\n" +
++			"Foo : bar\r\n\r\n"))
++		buf.Flush()
++		conn.Close()
++	}))
++	defer cst.close()
++	res, err := cst.c.Get(cst.ts.URL)
++	if err != nil {
++		t.Fatal(err)
++	}
++	defer res.Body.Close()
++	if v := res.Header.Get("Foo"); v != "" {
++		t.Errorf(`unexpected "Foo" header: %q`, v)
++	}
++	if v := res.Header.Get("Foo "); v != "bar" {
++		t.Errorf(`bad "Foo " header value: %q, want %q`, v, "bar")
++	}
++}
+diff --git a/src/net/textproto/reader.go b/src/net/textproto/reader.go
+index feb464b..6a37b2d 100644
+--- a/src/net/textproto/reader.go
++++ b/src/net/textproto/reader.go
+@@ -492,18 +492,12 @@ func (r *Reader) ReadMIMEHeader() (MIMEHeader, error) {
+ 			return m, err
+ 		}
+ 
+-		// Key ends at first colon; should not have trailing spaces
+-		// but they appear in the wild, violating specs, so we remove
+-		// them if present.
++		// Key ends at first colon.
+ 		i := bytes.IndexByte(kv, ':')
+ 		if i < 0 {
+ 			return m, ProtocolError("malformed MIME header line: " + string(kv))
+ 		}
+-		endKey := i
+-		for endKey > 0 && kv[endKey-1] == ' ' {
+-			endKey--
+-		}
+-		key := canonicalMIMEHeaderKey(kv[:endKey])
++		key := canonicalMIMEHeaderKey(kv[:i])
+ 
+ 		// As per RFC 7230 field-name is a token, tokens consist of one or more chars.
+ 		// We could return a ProtocolError here, but better to be liberal in what we
+diff --git a/src/net/textproto/reader_test.go b/src/net/textproto/reader_test.go
+index 7cff7b4..3af77d2 100644
+--- a/src/net/textproto/reader_test.go
++++ b/src/net/textproto/reader_test.go
+@@ -188,11 +188,10 @@ func TestLargeReadMIMEHeader(t *testing.T) {
+ 	}
+ }
+ 
+-// Test that we read slightly-bogus MIME headers seen in the wild,
+-// with spaces before colons, and spaces in keys.
++// TestReadMIMEHeaderNonCompliant checks that we don't normalize headers
++// with spaces before colons, and accept spaces in keys.
+ func TestReadMIMEHeaderNonCompliant(t *testing.T) {
+-	// Invalid HTTP response header as sent by an Axis security
+-	// camera: (this is handled by IE, Firefox, Chrome, curl, etc.)
++	// These invalid headers will be rejected by net/http according to RFC 7230.
+ 	r := reader("Foo: bar\r\n" +
+ 		"Content-Language: en\r\n" +
+ 		"SID : 0\r\n" +
+@@ -202,9 +201,9 @@ func TestReadMIMEHeaderNonCompliant(t *testing.T) {
+ 	want := MIMEHeader{
+ 		"Foo":              {"bar"},
+ 		"Content-Language": {"en"},
+-		"Sid":              {"0"},
+-		"Audio Mode":       {"None"},
+-		"Privilege":        {"127"},
++		"SID ":             {"0"},
++		"Audio Mode ":      {"None"},
++		"Privilege ":       {"127"},
+ 	}
+ 	if !reflect.DeepEqual(m, want) || err != nil {
+ 		t.Fatalf("ReadMIMEHeader =\n%v, %v; want:\n%v", m, err, want)