add _GNU_SOURCE to fix some warnings

CHANGELOG.md

@@ -5,7 +5,8 @@ UNRELEASED
 
 - Corrected long option name of -s to --stats (#148, thanks @wopfel)
 - Do not fail if using fping6 with -6 flag (#149, thanks @stromnet)
-- Fail if interface binding (-I) does not work (#162, by @kbucheli)
+- Fail if interface binding (-I) does not work (#162, thanks @kbucheli)
+- Fix using option -4 when fping is compiled IPv4-only (#154, thanks @pbhenson)
 
 fping 4.2 (2019-02-19)
 ======================

configure.ac

@@ -4,6 +4,7 @@ dnl Minimum Autoconf version required.
 AC_PREREQ(2.59)
 
 AC_INIT([fping],[4.2])
+AC_GNU_SOURCE
 
 dnl --disable-ipv4
 AC_ARG_ENABLE([ipv4],

src/fping.c

@@ -34,6 +34,7 @@
 extern "C" {
 #endif /* __cplusplus */
 
+#include "config.h"
 #include "fping.h"
 #include "options.h"
 #include "optparse.h"
@@ -44,7 +45,6 @@ extern "C" {
 #include <stdio.h>
 #include <time.h>
 
-#include "config.h"
 #include "seqmap.h"
 
 #ifdef HAVE_UNISTD_H
@@ -608,7 +608,7 @@ int main(int argc, char** argv)
             break;
 
         case 'H':
-            if (!(ttl = (u_int)atoi(optparse_state.optarg)))
+            if (!(ttl = (unsigned int)atoi(optparse_state.optarg)))
                 usage(1);
             break;
 

src/seqmap.c

@@ -35,6 +35,7 @@
  *           https://github.com/schweikert/fping/issues/48
  */
 
+#include "config.h"
 #include "seqmap.h"
 #include "limits.h"
 #include "options.h"