Update Channel ID API to use a callback.

openssl/ssl/s3_clnt.c

Index: openssl/ssl/s3_clnt.c
diff --git a/openssl/ssl/s3_clnt.c b/openssl/ssl/s3_clnt.c
index edbf6d0b88bf0c2329e7d33b8ad110c2ac8f93d3..1c2731ffb5e71e5a4eb2442d398c955125fe7849 100644
--- a/openssl/ssl/s3_clnt.c
+++ b/openssl/ssl/s3_clnt.c
@@ -3414,12 +3414,21 @@ int ssl3_send_channel_id(SSL *s)
 	if (s->state != SSL3_ST_CW_CHANNEL_ID_A)
 		return ssl3_do_write(s, SSL3_RT_HANDSHAKE);
 
-        if (s->tlsext_channel_id_private == NULL)
-            {
-                s->rwstate=SSL_CHANNEL_ID_LOOKUP;
-                return (-1);
-            }
-        s->rwstate=SSL_NOTHING;
+	if (!s->tlsext_channel_id_private && s->ctx->channel_id_cb)
+		{
+		EVP_PKEY* key = NULL;
+		s->ctx->channel_id_cb(s, &key);
+		if (key != NULL)
+			{
+			s->tlsext_channel_id_private = key;
+			}
+		}
+	if (!s->tlsext_channel_id_private)
+		{
+		s->rwstate=SSL_CHANNEL_ID_LOOKUP;
+		return (-1);
+		}
+	s->rwstate=SSL_NOTHING;
 
 	d = (unsigned char *)s->init_buf->data;
 	*(d++)=SSL3_MT_ENCRYPTED_EXTENSIONS;