Add client hello callback related functions

This exposes the OpenSSL functions SSL_CTX_set_client_hello_cb,
SSL_client_hello_get0_ext and SSL_client_hello_get1_extensions_present.

These are required to implement to the client hello callback
functionality in pyOpenSSL.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>

Author: schwabe

src/_cffi_src/openssl/ssl.py

@@ -351,6 +351,18 @@
 void SSL_CTX_set_tlsext_servername_callback(
     SSL_CTX *,
     int (*)(SSL *, int *, void *));
+void SSL_CTX_set_client_hello_cb(
+    SSL_CTX *c,
+    int (*)(SSL *, int *, void *),
+    void *arg);
+int SSL_client_hello_get1_extensions_present(
+    SSL *s, int **out,
+    size_t *outlen);
+int SSL_client_hello_get0_ext(
+    SSL *s, unsigned int type,
+    const unsigned char **out,
+    size_t *outlen);
+
 
 long SSL_set_tlsext_status_ocsp_resp(SSL *, unsigned char *, int);
 long SSL_get_tlsext_status_ocsp_resp(SSL *, const unsigned char **);