utility function

Reviewed-by: Matt Caswell <matt@openssl.org>

ssl/s3_lib.c

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index f3bf017..30fcd39 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -4639,3 +4639,16 @@
     EVP_PKEY_CTX_free(pctx);
     return rv;
 }
+
+EVP_PKEY *ssl_dh_to_pkey(DH *dh)
+{
+    EVP_PKEY *ret;
+    if (dh == NULL)
+        return NULL;
+    ret = EVP_PKEY_new();
+    if (EVP_PKEY_set1_DH(ret, dh) <= 0) {
+        EVP_PKEY_free(ret);
+        return NULL;
+    }
+    return ret;
+}

ssl/ssl_locl.h

diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index c213aa4..bff20ad 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -1859,6 +1859,7 @@
                                       int free_pms);
 __owur EVP_PKEY *ssl_generate_pkey(EVP_PKEY *pm, int nid);
 __owur int ssl_derive(SSL *s, EVP_PKEY *privkey, EVP_PKEY *pubkey);
+__owur EVP_PKEY *ssl_dh_to_pkey(DH *dh);
 
 __owur const SSL_CIPHER *ssl3_get_cipher_by_char(const unsigned char *p);
 __owur int ssl3_put_cipher_by_char(const SSL_CIPHER *c, unsigned char *p);