Provide a ssl_sigalg_for_peer() function and use in the TLSv1.3 code.

Provide an ssl_sigalg_for_peer() function that knows how to figure out
which signature algorithm should be used for a peer provided signature,
performing appropriate validation to ensure that the peer provided value
is suitable for the protocol version and key in use.

In the TLSv1.3 code, this replaces the need for separate calls to lookup
the sigalg from the peer provided value, then perform validation.

ok inoguchi@ tb@

1 files changed, 3 insertions, 1 deletions

diff --git a/src/lib/libssl/ssl_sigalgs.h b/src/lib/libssl/ssl_sigalgs.h
index 6905bba060..dffa0e0158 100644
--- a/src/lib/libssl/ssl_sigalgs.h
+++ b/src/lib/libssl/ssl_sigalgs.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_sigalgs.h,v 1.21 2021/06/29 19:10:08 jsing Exp $ */
+/* $OpenBSD: ssl_sigalgs.h,v 1.22 2021/06/29 19:20:39 jsing Exp $ */
 /*
  * Copyright (c) 2018-2019 Bob Beck <beck@openbsd.org>
  *
@@ -75,6 +75,8 @@ int ssl_sigalgs_build(uint16_t tls_version, CBB *cbb);
 int ssl_sigalg_pkey_ok(SSL *s, const struct ssl_sigalg *sigalg,
     EVP_PKEY *pkey);
 const struct ssl_sigalg *ssl_sigalg_select(SSL *s, EVP_PKEY *pkey);
+const struct ssl_sigalg *ssl_sigalg_for_peer(SSL *s, EVP_PKEY *pkey,
+    uint16_t sigalg_value);
 
 __END_HIDDEN_DECLS