Fix and improve SSL_MODE_SEND_FALLBACK_SCSV documentation.

Reviewed-by: Rich Salz <rsalz@openssl.org>

diff --git a/doc/ssl/SSL_CTX_set_mode.pod b/doc/ssl/SSL_CTX_set_mode.pod
index 8cb669daeb78c122e91fe5f7b5a625359d06e0d5..2a5aaa555e13ab058d81737f2ac5ec61350a2f87 100644 (file)
--- a/doc/ssl/SSL_CTX_set_mode.pod
+++ b/doc/ssl/SSL_CTX_set_mode.pod
@@ -71,6 +71,16 @@ SSL_CTX->freelist_max_len, which defaults to 32.  Using this flag can
 save around 34k per idle SSL connection.
 This flag has no effect on SSL v2 connections, or on DTLS connections.
 
+=item SSL_MODE_SEND_FALLBACK_SCSV
+
+Send TLS_FALLBACK_SCSV in the ClientHello.
+To be set only by applications that reconnect with a downgraded protocol
+version; see draft-ietf-tls-downgrade-scsv-00 for details.
+
+DO NOT ENABLE THIS if your application attempts a normal handshake.
+Only use this in explicit fallback retries, following the guidance
+in draft-ietf-tls-downgrade-scsv-00.
+
 =back
 
 =head1 RETURN VALUES

diff --git a/ssl/ssl.h b/ssl/ssl.h
index b78a1cce4409f91cec21c3d5115e440c5bba107a..e61413c0437c588ba129fa2e2e532dc675b1b30e 100644 (file)
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -654,8 +654,13 @@ struct ssl_session_st
 #define SSL_MODE_SEND_CLIENTHELLO_TIME 0x00000020L
 #define SSL_MODE_SEND_SERVERHELLO_TIME 0x00000040L
 /* Send TLS_FALLBACK_SCSV in the ClientHello.
- * To be set by applications that reconnect with a downgraded protocol
- * version; see draft-ietf-tls-downgrade-scsv-00 for details. */
+ * To be set only by applications that reconnect with a downgraded protocol
+ * version; see draft-ietf-tls-downgrade-scsv-00 for details.
+ *
+ * DO NOT ENABLE THIS if your application attempts a normal handshake.
+ * Only use this in explicit fallback retries, following the guidance
+ * in draft-ietf-tls-downgrade-scsv-00.
+ */
 #define SSL_MODE_SEND_FALLBACK_SCSV 0x00000080L
 
 /* Note: SSL[_CTX]_set_{options,mode} use |= op on the previous value,