Switch the legacy version to TLS1_2_VERSION when processing server hello.

Switch the legacy version when processing the server hello, rather than
when the client hello has been sent. This ensures that we accept a
response from the server that has a record version other than
TLS1_2_VERSION, as is the case where the server is negotiating TLSv1.0
or TLSv1.1.

Issue spotted by inoguchi@

ok inoguchi@ tb@

1 files changed, 2 insertions, 2 deletions

diff --git a/src/lib/libssl/tls13_client.c b/src/lib/libssl/tls13_client.c
index 951c0f841c..dbd5b0add7 100644
--- a/src/lib/libssl/tls13_client.c
+++ b/src/lib/libssl/tls13_client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_client.c,v 1.58 2020/05/10 16:56:11 jsing Exp $ */
+/* $OpenBSD: tls13_client.c,v 1.59 2020/05/13 17:51:48 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -145,7 +145,6 @@ tls13_client_hello_send(struct tls13_ctx *ctx, CBB *cbb)
 int
 tls13_client_hello_sent(struct tls13_ctx *ctx)
 {
-        tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION);
         tls13_record_layer_allow_ccs(ctx->rl, 1);
 
         tls1_transcript_freeze(ctx->ssl);
@@ -252,6 +251,7 @@ tls13_server_hello_process(struct tls13_ctx *ctx, CBS *cbs)
         }
 
         /* From here on in we know we are doing TLSv1.3. */
+        tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION);
         tls13_record_layer_allow_legacy_alerts(ctx->rl, 0);
 
         /* See if this is a HelloRetryRequest. */