Use the fallback nsock engine by default in order to maximize

compatibility between systems and use cases. [Henri Doreau]

There were known issues with the following cases:
  * epoll and regular files
  * kqueue and regular files
  * WSAPoll and stdin

The --nsock-engine=<ENGINE> can still be used to bypass this
default choice.

See: http://seclists.org/nmap-dev/2012/q4/173

CHANGELOG

@@ -1,5 +1,8 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [Ncat] Use the fallback nsock engine by default in order to maximize
+  compatibility between systems and use cases. [Henri Doreau]
+
 o [Ncat] Added support for Unix domain sockets. The new -U and
   --unixsock options activate this mode. [Tomas Hozza]
 

ncat/ncat_connect.c

@@ -477,37 +477,17 @@ bail:
     return -1;
 }
 
-#if defined(LINUX)
-static int stdin_is_reg(void) {
-  struct stat buf;
-
-  if (fstat(STDIN_FILENO, &buf) < 0)
-    bye("fstat(): %s", strerror(errno));
-
-  return S_ISREG(buf.st_mode);
-}
-#endif
-
 int ncat_connect(void)
 {
     nsock_pool mypool;
     int rc;
 
-#if defined(LINUX)
-    /* -- Hack!!
-     * epoll(7) doesn't support regular files (e.g.: ncat < file.c)
-     * If we detect that STDIN is a regular file, then we enforce
-     * the use of the select-based engine. */
-    if (stdin_is_reg())
-      nsock_set_default_engine("select");
-#elif defined(WIN32)
-    /* -- Hack!!
-     * Unconditionally use the select engine on windows.
-     * The poll engine (WSAPoll) is currently unable to handle
-     * read events on stdin.
+    /* Unless explicitely asked not to do so, ncat uses the
+     * fallback nsock engine to maximize compatibility between
+     * operating systems and the different use cases.
      */
-    nsock_set_default_engine("select");
-#endif
+    if (!o.nsock_engine)
+        nsock_set_default_engine("select");
 
     /* Create an nsock pool */
     if ((mypool = nsp_new(NULL)) == NULL)

ncat/ncat_core.c

@@ -160,6 +160,8 @@ void options_init(void)
     addrset_init(&o.denyset);
     o.httpserver = 0;
 
+    o.nsock_engine = 0;
+
     o.numsrcrtes = 0;
     o.srcrteptr = 4;
 

ncat/ncat_core.h

@@ -142,6 +142,7 @@ struct options {
     struct addrset allowset;
     struct addrset denyset;
     int httpserver;
+    int nsock_engine;
 
     /* Loose source-routing stuff */
     struct in_addr srcrtes[8];

ncat/ncat_main.c

@@ -424,6 +424,7 @@ int main(int argc, char *argv[])
             } else if (strcmp(long_options[option_index].name, "nsock-engine") == 0) {
                 if (nsock_set_default_engine(optarg) < 0)
                     bye("Unknown or non-available engine: %s.", optarg);
+                o.nsock_engine = 1;
             } else if (strcmp(long_options[option_index].name, "broker") == 0) {
                 o.broker = 1;
                 /* --broker implies --listen. */