Add mud_is_up()

mud.c

@@ -649,6 +649,18 @@ int mud_can_pull (struct mud *mud)
     return (mud->rx.start != MUD_PACKET_NEXT(mud->rx.end));
 }
 
+int mud_is_up (struct mud *mud)
+{
+    struct path *path;
+
+    int ret = 0;
+
+    for (path = mud->path; path; path = path->next)
+        ret += path->up;
+
+    return ret;
+}
+
 int mud_pull (struct mud *mud)
 {
     unsigned char ctrl[1024];

mud.h

@@ -14,6 +14,7 @@ int mud_bind (struct mud *, const char *);
 int mud_peer (struct mud *, const char *, const char *);
 
 int mud_can_pull (struct mud *);
+int mud_is_up    (struct mud *);
 
 int mud_pull (struct mud *);
 int mud_push (struct mud *);