irc: add option irc.network.sasl_fail_unavailable (closes #600)

Previously SASL did not fail when it was set up for the server but wasn't
supported by it. This makes no difference when the server's sasl_fail is
set to "continue" but might make a difference if set to "disconnect" or
"reconnect".
To make sure server connection is not made under such circumstances, this
patch adds an extra configurable ("on" by default) check to trigger SASL
failure when it is set up but not supported by the server. Although not
directly a SASL failure, this makes SASL not-authenticated scenarios all
handled consistently, while providing extra security by not silently
ignoring not being authenticated as requested.

3 files changed, 22 insertions, 1 deletions

diff --git a/src/plugins/irc/irc-config.c b/src/plugins/irc/irc-config.c
index ef3929d38..d7252fbec 100644
--- a/src/plugins/irc/irc-config.c
+++ b/src/plugins/irc/irc-config.c
@@ -142,6 +142,7 @@ struct t_config_option *irc_config_network_lag_reconnect;
 struct t_config_option *irc_config_network_lag_refresh_interval;
 struct t_config_option *irc_config_network_notify_check_ison;
 struct t_config_option *irc_config_network_notify_check_whois;
+struct t_config_option *irc_config_network_sasl_fail_unavailable;
 struct t_config_option *irc_config_network_send_unknown_commands;
 struct t_config_option *irc_config_network_whois_double_nick;
 
@@ -3004,6 +3005,12 @@ irc_config_init ()
            "(in minutes)"),
         NULL, 1, 60 * 24 * 7, "5", NULL, 0, NULL, NULL,
         &irc_config_change_network_notify_check_whois, NULL, NULL, NULL);
+    irc_config_network_sasl_fail_unavailable = weechat_config_new_option (
+        irc_config_file, ptr_section,
+        "sasl_fail_unavailable", "boolean",
+        N_("cause SASL authentication failure when SASL is requested but "
+           "unavailable"),
+        NULL, 0, 0, "on", NULL, 0, NULL, NULL, NULL, NULL, NULL, NULL);
     irc_config_network_send_unknown_commands = weechat_config_new_option (
         irc_config_file, ptr_section,
         "send_unknown_commands", "boolean",
diff --git a/src/plugins/irc/irc-config.h b/src/plugins/irc/irc-config.h
index fd18cf532..91d9b6bfe 100644
--- a/src/plugins/irc/irc-config.h
+++ b/src/plugins/irc/irc-config.h
@@ -183,6 +183,7 @@ extern struct t_config_option *irc_config_network_lag_reconnect;
 extern struct t_config_option *irc_config_network_lag_refresh_interval;
 extern struct t_config_option *irc_config_network_notify_check_ison;
 extern struct t_config_option *irc_config_network_notify_check_whois;
+extern struct t_config_option *irc_config_network_sasl_fail_unavailable;
 extern struct t_config_option *irc_config_network_send_unknown_commands;
 extern struct t_config_option *irc_config_network_whois_double_nick;
 
diff --git a/src/plugins/irc/irc-protocol.c b/src/plugins/irc/irc-protocol.c
index f7b20111d..23afad170 100644
--- a/src/plugins/irc/irc-protocol.c
+++ b/src/plugins/irc/irc-protocol.c
@@ -345,7 +345,7 @@ IRC_PROTOCOL_CALLBACK(cap)
     const char *ptr_cap_option;
     int num_caps_supported, num_caps_requested, num_caps_added;
     int num_caps_removed, sasl_requested, sasl_to_do, sasl_mechanism;
-    int i, j, timeout, length;
+    int sasl_fail, i, j, timeout, length;
 
     IRC_PROTOCOL_MIN_ARGS(4);
 
@@ -429,6 +429,19 @@ IRC_PROTOCOL_CALLBACK(cap)
                             server->buffer,
                             _("%s%s: client capability: SASL not supported"),
                             weechat_prefix ("network"), IRC_PLUGIN_NAME);
+
+                        if (weechat_config_boolean (irc_config_network_sasl_fail_unavailable))
+                        {
+                            /* same handling as for sasl_end_fail */
+                            sasl_fail = IRC_SERVER_OPTION_INTEGER(server, IRC_SERVER_OPTION_SASL_FAIL);
+                            if ((sasl_fail == IRC_SERVER_SASL_FAIL_RECONNECT)
+                                || (sasl_fail == IRC_SERVER_SASL_FAIL_DISCONNECT))
+                            {
+                                irc_server_disconnect (
+                                    server, 0,
+                                    (sasl_fail == IRC_SERVER_SASL_FAIL_RECONNECT) ? 1 : 0);
+                            }
+                        }
                     }
                 }
                 if (cap_option)