Add an interface for QUIC integration.

0-RTT support and APIs to consume NewSessionTicket will be added in a
follow-up.

Change-Id: Ib2b2c6b618b3e33a74355fb53fdbd2ffafcc5c56
Reviewed-on: https://boringssl-review.googlesource.com/c/31744
Commit-Queue: Steven Valdez <svaldez@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

ssl/ssl_versions.cc

diff --git a/ssl/ssl_versions.cc b/ssl/ssl_versions.cc
index 911fb7e..7df7fe7 100644
--- a/ssl/ssl_versions.cc
+++ b/ssl/ssl_versions.cc
@@ -217,6 +217,11 @@
   uint16_t min_version = hs->config->conf_min_version;
   uint16_t max_version = hs->config->conf_max_version;
 
+  // QUIC requires TLS 1.3.
+  if (hs->ssl->ctx->quic_method && min_version < TLS1_3_VERSION) {
+    min_version = TLS1_3_VERSION;
+  }
+
   // OpenSSL's API for controlling versions entails blacklisting individual
   // protocols. This has two problems. First, on the client, the protocol can
   // only express a contiguous range of versions. Second, a library consumer