Add code to re-use an existing ctrl_iface socket file

Port the code from wpa_supplicant to re-use an existing ctrl_iface
socket file if the file does not seem to be in use. This allows
hostapd to recover from unclean shutdown of the control interface.

diff --git a/hostapd/ctrl_iface.c b/hostapd/ctrl_iface.c
index 0245f93..f7ac69e 100644 (file)
--- a/hostapd/ctrl_iface.c
+++ b/hostapd/ctrl_iface.c
@@ -484,8 +484,35 @@ int hostapd_ctrl_iface_init(struct hostapd_data *hapd)
                goto fail;
        os_strlcpy(addr.sun_path, fname, sizeof(addr.sun_path));
        if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
-               perror("bind(PF_UNIX)");
-               goto fail;
+               wpa_printf(MSG_DEBUG, "ctrl_iface bind(PF_UNIX) failed: %s",
+                          strerror(errno));
+               if (connect(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+                       wpa_printf(MSG_DEBUG, "ctrl_iface exists, but does not"
+                                  " allow connections - assuming it was left"
+                                  "over from forced program termination");
+                       if (unlink(fname) < 0) {
+                               perror("unlink[ctrl_iface]");
+                               wpa_printf(MSG_ERROR, "Could not unlink "
+                                          "existing ctrl_iface socket '%s'",
+                                          fname);
+                               goto fail;
+                       }
+                       if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) <
+                           0) {
+                               perror("bind(PF_UNIX)");
+                               goto fail;
+                       }
+                       wpa_printf(MSG_DEBUG, "Successfully replaced leftover "
+                                  "ctrl_iface socket '%s'", fname);
+               } else {
+                       wpa_printf(MSG_INFO, "ctrl_iface exists and seems to "
+                                  "be in use - cannot override it");
+                       wpa_printf(MSG_INFO, "Delete '%s' manually if it is "
+                                  "not used anymore", fname);
+                       os_free(fname);
+                       fname = NULL;
+                       goto fail;
+               }
        }
 
        if (hapd->conf->ctrl_interface_gid_set &&