Make --nobind default for --pull

Currently we default to local binding with udp. But the majority of
configuration files actually uses --nobind in the configuration to
change the default for --client. And client protocols should normally
use a random source port. This changes the default. Local binding with
--client can still be done using --bind.

This commit refactors the current code to be more easy to add to understand
and adds the the o->pull condition as additional option to opt into setting
local binding to false.

Patch v2: add more commments

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20211206010007.3072528-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23303.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/Changes.rst b/Changes.rst
index e83dda023d573e70e1298a0b128777451bd40ce1..b7d7f20544f99fbd0ddec546cf3069810ac2833b 100644 (file)
--- a/Changes.rst
+++ b/Changes.rst
@@ -120,7 +120,8 @@ PF (Packet Filtering) support has been removed
 User-visible Changes
 --------------------
 - CHACHA20-POLY1305 is included in the default of ``--data-ciphers`` when available.
-- Option ``--prng`` is ignored as we rely on the SSL library radnom generator.
+- Option ``--prng`` is ignored as we rely on the SSL library random number generator.
+- Option ``--nobind`` is default when ``--client`` or ``--pull`` is used in the configuration
 
 Overview of changes in 2.5
 ==========================

diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 928f7e8a3b2d6a3e1664b7b3b3a5d1624213dad9..ac13412a44fdb68a8caef01e4cbc847c4daf44d1 100644 (file)
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -2859,14 +2859,16 @@ options_postprocess_mutate_ce(struct options *o, struct connection_entry *ce)
         }
     }
 
-    if (ce->proto == PROTO_TCP_CLIENT && !ce->local
-        && !ce->local_port_defined && !ce->bind_defined)
-    {
-        ce->bind_local = false;
-    }
+    /* an option is present that requires local bind to enabled */
+    bool need_bind = ce->local || ce->local_port_defined || ce->bind_defined;
+
+    /* socks proxy is enabled */
+    bool uses_socks = ce->proto == PROTO_UDP && ce->socks_proxy_server;
 
-    if (ce->proto == PROTO_UDP && ce->socks_proxy_server && !ce->local
-        && !ce->local_port_defined && !ce->bind_defined)
+    /* If binding is not forced by an explicit option and we have (at least)
+     * one of --tcp-client, --pull (or --client), or socks we do not bind
+     * locally to have "normal" IP client behaviour of a random source port */
+    if (!need_bind && (ce->proto == PROTO_TCP_CLIENT || uses_socks || o->pull))
     {
         ce->bind_local = false;
     }