Never send SNI warning alerts.

TLS 1.3 forbids warning alerts, and sending these is a bad idea. Per RFC

   If the server understood the ClientHello extension but
   does not recognize the server name, the server SHOULD take one of two
   actions: either abort the handshake by sending a fatal-level
   unrecognized_name(112) alert or continue the handshake.  It is NOT
   RECOMMENDED to send a warning-level unrecognized_name(112) alert,
   because the client's behavior in response to warning-level alerts is

The motivation is to cut down on the number of places where we send
non-closing alerts. We can't remove them yet (SSL 3.0 and TLS 1.3 draft
18 need to go), but eventually this can be a simplifying assumption.
Already this means DTLS never sends warning alerts, which is good
because DTLS can't retransmit them.

Change-Id: I577a1eb9c23e66d28235c0fbe913f00965e19486
Reviewed-by: Adam Langley <>
2 files changed
tree: 3d2fc3a56cd618195f5a91b28d046495acf67e9a
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. infra/
  7. ssl/
  8. third_party/
  9. tool/
  10. util/
  11. .clang-format
  12. .gitignore
  15. CMakeLists.txt
  16. codereview.settings


BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

There are other files in this directory which might be helpful: