ha: Recreate the control FIFO if the file exists but is not a FIFO

This may happen if something like `echo ... > /path/to/fifo` is used
before the plugin was able to create the FIFO. In that case we'd end
up in a loop always reading the same values from the static file.

diff --git a/src/libcharon/plugins/ha/ha_ctl.c b/src/libcharon/plugins/ha/ha_ctl.c
index a95499742f0284c619937c2898b7754011956fd0..27ebb91c5e0602fd824cb26ebac257000813be59 100644 (file)
--- a/src/libcharon/plugins/ha/ha_ctl.c
+++ b/src/libcharon/plugins/ha/ha_ctl.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Tobias Brunner
  * Copyright (C) 2008 Martin Willi
  * Hochschule fuer Technik Rapperswil
  *
@@ -50,6 +51,41 @@ struct private_ha_ctl_t {
        ha_cache_t *cache;
 };
 
+/**
+ * Change the permissions of the control FIFO, returns TRUE on success
+ */
+static bool change_fifo_permissions()
+{
+       if (chown(HA_FIFO, lib->caps->get_uid(lib->caps),
+                         lib->caps->get_gid(lib->caps)) != 0)
+       {
+               DBG1(DBG_CFG, "changing HA FIFO permissions failed: %s",
+                        strerror(errno));
+               return FALSE;
+       }
+       return TRUE;
+}
+
+/**
+ * Deletes and creates the control FIFO, returns TRUE on success
+ */
+static bool recreate_fifo()
+{
+       mode_t old;
+       bool success = TRUE;
+
+       unlink(HA_FIFO);
+       old = umask(S_IRWXO);
+       if (mkfifo(HA_FIFO, S_IRUSR | S_IWUSR) != 0)
+       {
+               DBG1(DBG_CFG, "creating HA FIFO %s failed: %s", HA_FIFO,
+                        strerror(errno));
+               success = FALSE;
+       }
+       umask(old);
+       return success && change_fifo_permissions();
+}
+
 /**
  * FIFO dispatching function
  */
@@ -59,13 +95,22 @@ static job_requeue_t dispatch_fifo(private_ha_ctl_t *this)
        bool oldstate;
        char buf[8];
        u_int segment;
+       struct stat sb;
 
        oldstate = thread_cancelability(TRUE);
        fifo = open(HA_FIFO, O_RDONLY);
        thread_cancelability(oldstate);
-       if (fifo == -1)
+       if (fifo == -1 || fstat(fifo, &sb) != 0 || !S_ISFIFO(sb.st_mode))
        {
-               DBG1(DBG_CFG, "opening HA fifo failed: %s", strerror(errno));
+               if (fifo == -1 && errno != ENOENT)
+               {
+                       DBG1(DBG_CFG, "opening HA FIFO failed: %s", strerror(errno));
+               }
+               else
+               {
+                       DBG1(DBG_CFG, "%s is not a FIFO, recreate it", HA_FIFO);
+                       recreate_fifo();
+               }
                sleep(1);
                return JOB_REQUEUE_FAIR;
        }
@@ -100,6 +145,7 @@ static job_requeue_t dispatch_fifo(private_ha_ctl_t *this)
 METHOD(ha_ctl_t, destroy, void,
        private_ha_ctl_t *this)
 {
+       unlink(HA_FIFO);
        free(this);
 }
 
@@ -109,7 +155,7 @@ METHOD(ha_ctl_t, destroy, void,
 ha_ctl_t *ha_ctl_create(ha_segments_t *segments, ha_cache_t *cache)
 {
        private_ha_ctl_t *this;
-       mode_t old;
+       struct stat sb;
 
        INIT(this,
                .public = {
@@ -119,20 +165,30 @@ ha_ctl_t *ha_ctl_create(ha_segments_t *segments, ha_cache_t *cache)
                .cache = cache,
        );
 
-       if (access(HA_FIFO, R_OK|W_OK) != 0)
+       if (stat(HA_FIFO, &sb) == 0)
        {
-               old = umask(S_IRWXO);
-               if (mkfifo(HA_FIFO, S_IRUSR | S_IWUSR) != 0)
+               if (!S_ISFIFO(sb.st_mode))
+               {
+                       DBG1(DBG_CFG, "%s is not a FIFO, recreate it", HA_FIFO);
+                       recreate_fifo();
+               }
+               else if (access(HA_FIFO, R_OK|W_OK) != 0)
+               {
+                       DBG1(DBG_CFG, "accessing HA FIFO %s denied, recreate it", HA_FIFO);
+                       recreate_fifo();
+               }
+               else
                {
-                       DBG1(DBG_CFG, "creating HA FIFO %s failed: %s",
-                                HA_FIFO, strerror(errno));
+                       change_fifo_permissions();
                }
-               umask(old);
        }
-       if (chown(HA_FIFO, lib->caps->get_uid(lib->caps),
-                         lib->caps->get_gid(lib->caps)) != 0)
+       else if (errno == ENOENT)
        {
-               DBG1(DBG_CFG, "changing HA FIFO permissions failed: %s",
+               recreate_fifo();
+       }
+       else
+       {
+               DBG1(DBG_CFG, "accessing HA FIFO %s failed: %s", HA_FIFO,
                         strerror(errno));
        }
 
@@ -141,4 +197,3 @@ ha_ctl_t *ha_ctl_create(ha_segments_t *segments, ha_cache_t *cache)
                        this, NULL, (callback_job_cancel_t)return_false, JOB_PRIO_CRITICAL));
        return &this->public;
 }
-