test: Add dummy ChangeCipherSpec after ClientHello

src/mtp_fake_tls.erl

@@ -21,6 +21,7 @@
 -ifdef(TEST).
 -export([make_client_hello/2,
          make_client_hello/4,
+         make_dummy_change_cipher/0,
          parse_server_hello/1]).
 -endif.
 
@@ -295,6 +296,13 @@ add_padding_ext(RealExtensions, ExtLen) ->
                    (binary:copy(<<0>>, PadSize))/binary>>,
     <<RealExtensions/binary, PaddingExt/binary>>.
 
+%% https://tools.ietf.org/html/rfc8446#appendix-D.4
+make_dummy_change_cipher() ->
+    <<?TLS_REC_CHANGE_CIPHER,
+      ?TLS_12_VERSION,
+      1:?u16,
+      1>>.
+
 %% Parses "ServerHello" (the one produced by from_client_hello/2). Used for tests only.
 parse_server_hello(<<?TLS_REC_HANDSHAKE, ?TLS_12_VERSION, HSLen:?u16, Handshake:HSLen/binary,
                      ?TLS_REC_CHANGE_CIPHER, ?TLS_12_VERSION, CCLen:?u16, ChangeCipher:CCLen/binary,

test/mtp_test_client.erl

@@ -49,6 +49,7 @@ connect(Host, Port, Seed, Secret, DcId, Protocol0) ->
                 ok = gen_tcp:send(Sock, ClientHello),
                 %% Let's hope whole server hello will arrive in a single chunk
                 Tail_ = recv_server_hello(Sock, Timeout, <<>>),
+                ok = gen_tcp:send(Sock, mtp_fake_tls:make_dummy_change_cipher()),
                 {mtp_secure, true, mtp_fake_tls:new(), Tail_};
             _ -> {Protocol0, false, undefined, <<>>}
         end,