ipcalc applet by Stephan Linz and Jordan Crouse
diff --git a/networking/Makefile.in b/networking/Makefile.in
index d249c04..7404b04 100644
--- a/networking/Makefile.in
+++ b/networking/Makefile.in
@@ -27,6 +27,7 @@
 NETWORKING-$(CONFIG_IFCONFIG)		+= ifconfig.o
 NETWORKING-$(CONFIG_IFUPDOWN)		+= ifupdown.o
 NETWORKING-$(CONFIG_IP)		    += ip.o
+NETWORKING-$(CONFIG_IPCALC)             += ipcalc.o
 NETWORKING-$(CONFIG_NC)		    += nc.o
 NETWORKING-$(CONFIG_NETSTAT)		+= netstat.o
 NETWORKING-$(CONFIG_NSLOOKUP)		+= nslookup.o
diff --git a/networking/config.in b/networking/config.in
index 7393feb..27a8ab5 100644
--- a/networking/config.in
+++ b/networking/config.in
@@ -30,6 +30,10 @@
     bool '  route'		CONFIG_FEATURE_IP_ROUTE
     bool '  tunnel'		CONFIG_FEATURE_IP_TUNNEL
 fi
+bool 'ipcalc'	    CONFIG_IPCALC
+if [ "$CONFIG_IPCALC" = "y" ]; then
+    bool '  Fancy IPCALC, more options, adds 300 bytes'	CONFIG_FEATURE_IPCALC_FANCY
+fi
 bool 'nc'	    CONFIG_NC
 bool 'netstat'	    CONFIG_NETSTAT
 bool 'nslookup'	    CONFIG_NSLOOKUP
diff --git a/networking/ipcalc.c b/networking/ipcalc.c
new file mode 100644
index 0000000..f130f3b
--- /dev/null
+++ b/networking/ipcalc.c
@@ -0,0 +1,164 @@
+/* vi: set sw=4 ts=4 ai: */
+/*
+ * Mini ipcalc implementation for busybox
+ *
+ * By Jordan Crouse <jordan@cosmicpenguin.net>
+ *    Stephan Linz  <linz@li-pro.net>
+ *
+ * This is a complete reimplentation of the ipcalc program
+ * from Redhat.  I didn't look at their source code, but there
+ * is no denying that this is a loving reimplementation
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <getopt.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include "busybox.h"
+
+#define IPCALC_MSG(CMD,ALTCMD) if (mode & SILENT) {ALTCMD;} else {CMD;}
+
+static unsigned long get_netmask(unsigned long ipaddr)
+{
+	if (ipaddr & 0xC0) {
+		return 0x00FFFFFF;	/* Class C */
+	}
+	if (ipaddr & 0x10) {
+		return 0x0000FFFF;	/* Class B */
+	}
+	return 0x000000FF;	/* Class A */
+}
+
+#define NETMASK   0x01
+#define BROADCAST 0x02
+#define NETWORK   0x04
+#define HOSTNAME  0x08
+#define SILENT    0x80
+
+int ipcalc_main(int argc, char **argv)
+{
+	unsigned char mode = 0;
+
+	unsigned long netmask = 0;
+	unsigned long broadcast = 0;
+	unsigned long network = 0;
+	unsigned long ipaddr = 0;
+
+	int opt = 0;
+
+	struct option long_options[] = {
+		{"netmask", no_argument, NULL, 'n'},
+		{"broadcast", no_argument, NULL, 'b'},
+		{"network", no_argument, NULL, 'w'},
+#ifdef CONFIG_FEATURE_IPCALC_FANCY
+		{"hostname", no_argument, NULL, 'h'},
+		{"silent", no_argument, NULL, 's'},
+#endif
+		{NULL, 0, NULL, 0}
+	};
+
+
+	while ((opt = getopt_long(argc, argv,
+#ifdef CONFIG_FEATURE_IPCALC_FANCY
+							  "nbwhs",
+#else
+							  "nbw",
+#endif
+							  long_options, NULL)) != EOF) {
+		if (opt == 'n')
+			mode |= NETMASK;
+		else if (opt == 'b')
+			mode |= BROADCAST;
+		else if (opt == 'w')
+			mode |= NETWORK;
+#ifdef CONFIG_FEATURE_IPCALC_FANCY
+		else if (opt == 'h')
+			mode |= HOSTNAME;
+		else if (opt == 's')
+			mode |= SILENT;
+#endif
+		else {
+			show_usage();
+		}
+	}
+
+	if (mode & (BROADCAST | NETWORK)) {
+		if (argc - optind > 2) {
+			show_usage();
+		}
+	} else {
+		if (argc - optind != 1) {
+			show_usage();
+		}
+	}
+
+	ipaddr = inet_addr(argv[optind]);
+
+	if (ipaddr == INADDR_NONE) {
+		IPCALC_MSG(error_msg_and_die("bad IP address: %s\n", argv[optind]),
+				   exit(EXIT_FAILURE));
+	}
+
+
+	if (argc - optind == 2) {
+		netmask = inet_addr(argv[optind + 1]);
+	}
+
+	if (ipaddr == INADDR_NONE) {
+		IPCALC_MSG(error_msg_and_die("bad netmask: %s\n", argv[optind + 1]),
+				   exit(EXIT_FAILURE));
+	}
+
+	/* JHC - If the netmask wasn't provided then calculate it */
+	if (!netmask) {
+		netmask = get_netmask(ipaddr);
+	}
+
+	if (mode & NETMASK) {
+		printf("NETMASK=%s\n", inet_ntoa((*(struct in_addr *) &netmask)));
+	}
+
+	if (mode & BROADCAST) {
+		broadcast = (ipaddr & netmask) | ~netmask;
+		printf("BROADCAST=%s\n", inet_ntoa((*(struct in_addr *) &broadcast)));
+	}
+
+	if (mode & NETWORK) {
+		network = ipaddr & netmask;
+		printf("NETWORK=%s\n", inet_ntoa((*(struct in_addr *) &network)));
+	}
+#ifdef CONFIG_FEATURE_IPCALC_FANCY
+	if (mode & HOSTNAME) {
+		struct hostent *hostinfo;
+		int x;
+
+		hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
+		if (!hostinfo) {
+			IPCALC_MSG(error_msg("cannot find hostname for %s", argv[optind]);
+					   herror(NULL);
+					   putc('\n', stderr);,);
+			exit(EXIT_FAILURE);
+		}
+		for (x = 0; hostinfo->h_name[x]; x++) {
+			hostinfo->h_name[x] = tolower(hostinfo->h_name[x]);
+		}
+
+		printf("HOSTNAME=%s\n", hostinfo->h_name);
+	}
+#endif
+
+	return EXIT_SUCCESS;
+}
+
+/* END CODE */
+/*
+Local Variables:
+c-file-style: "linux"
+c-basic-offset: 4
+tab-width: 4
+End:
+*/