1 files changed, 87 insertions, 0 deletions
diff --git a/source/n/net-tools/ipmask.c b/source/n/net-tools/ipmask.c
new file mode 100644
index 00000000..6be37c31
--- /dev/null
+++ b/source/n/net-tools/ipmask.c
@@ -0,0 +1,87 @@
+/* ipmask.c
+ *
+ * Given argv[1] as a decimal netmask and argv[2] as a decimal IP address,
+ * print the resulting broadcast and network addresses to stdout.  This is
+ * potentially useful in scripts which need the broadcast address and the
+ * network address but want to ask the user as few questions as possible.
+ *
+ * Copyright 1994 by David Niemi.  Written in about 30 minutes on 13 Aug.
+ * The author places no restrictions on the use of this program, provided
+ * that this copyright is preserved in any derived source code.
+ *
+ * Typical compilation command for Linux:
+ *	cc ipmask.c -Wall -O -m486 -N -o ipmask -s
+ */
+
+#define MYNAME "ipmask"
+
+#include <stdio.h>
+
+void Usage(void) {
+	fprintf (stderr,
+		"USAGE: %s <decimal netmask> <decimal IP address>\n",
+		MYNAME);
+}
+
+int main(int argc, char *argv[])
+{
+unsigned long netmask, ipaddr, netaddr, broadcast;
+int in[4], j;
+unsigned char bc[4],na[4];
+
+	if (3 != argc) {
+		Usage();
+		exit(1);
+	}
+
+	/* Check netmask */
+	if (4 != sscanf(argv[1],"%d.%d.%d.%d", &in[0],&in[1],&in[2],&in[3])) {
+		fprintf (stderr,"Invalid netmask \"%s\".\n", argv[1]);
+		Usage();
+		exit(1);
+	}
+	for (j=0; j<4; ++j) {
+		if (in[j]<0 || in[j]>255) {
+			fprintf (stderr,
+				"Invalid octet %d in netmask \"%s\".\n",
+				j+1, argv[1]);
+			Usage();
+			exit(1);
+		}
+	}
+	netmask = in[3] + 256 * (in[2] + 256 * (in[1] + 256 * in[0]));
+
+	/* Check IP address */
+	if (4 != sscanf(argv[2],"%d.%d.%d.%d", &in[0],&in[1],&in[2],&in[3])) {
+		fprintf (stderr,"Invalid IP address \"%s\".\n", argv[2]);
+		Usage();
+		exit(1);
+	}
+	for (j=0; j<4; ++j) {
+		if (in[j]<0 || in[j]>255) {
+			fprintf (stderr,
+				"Invalid octet %d in IP address \"%s\".\n",
+				j+1, argv[1]);
+			Usage();
+			exit(1);
+		}
+	}
+	ipaddr = in[3] + 256 * (in[2] + 256 * (in[1] + 256 * in[0]));
+
+	broadcast = ipaddr | (~ netmask);
+	bc[0] = broadcast / 256 / 256 / 256;
+	bc[1] = (broadcast / 256 / 256) % 256;
+	bc[2] = (broadcast / 256) % 256;
+	bc[3] = broadcast % 256;
+
+	netaddr = ipaddr & netmask;
+	na[0] = netaddr / 256 / 256 / 256;
+	na[1] = (netaddr / 256 / 256) % 256;
+	na[2] = (netaddr / 256) % 256;
+	na[3] = netaddr % 256;
+
+	printf ("%d.%d.%d.%d %d.%d.%d.%d\n",
+		bc[0], bc[1], bc[2], bc[3], na[0], na[1], na[2], na[3]);
+
+	exit(0);
+}