Added code for calculating ip subnets.

1 files changed, 106 insertions, 0 deletions

diff --git a/src/ipmunge.c b/src/ipmunge.c
new file mode 100644
index 0000000..44212e0
--- /dev/null
+++ b/src/ipmunge.c
@@ -0,0 +1,106 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include "md5.h"
+
+static void
+usage()
+{
+    fprintf(stderr, "usage: ipmunge [-s data] templ mask\n");
+	exit(2);
+}
+
+static int
+md5_file(FILE* f, MD5_CTX *ctx)
+{
+	#define BUF_SIZE 128
+	unsigned char buf[BUF_SIZE];
+	int r, read = 0;
+
+	while(!feof(f))
+	{
+		r = fread(buf, 1, BUF_SIZE, f);
+
+		if(ferror(f))
+			err(1, "couldn't read input data");
+
+		read += r;
+		MD5Update(ctx, buf, r);
+	}
+
+	return read;
+}
+
+int
+main(int argc, char* argv[])
+{
+	MD5_CTX ctx;
+	struct in_addr templ;
+	struct in_addr mask;
+	struct in_addr result;
+	const char* data = NULL;
+	int ch, l, i;
+	int count = 1;
+
+	memset(&result, 0, sizeof(result));
+	memset(&mask, 0, sizeof(mask));
+	memset(&templ, 0, sizeof(templ));
+
+	while((ch = getopt(argc, argv, "s:")) != -1)
+	{
+		switch(ch)
+		{
+		case 's':
+			data = optarg;
+			break;
+        case '?':
+        default:
+            usage();
+            break;
+		}
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	if(argc != 2)
+		usage();
+
+	if(!inet_aton(argv[0], &templ))
+		errx(1, "invalid template address: %s", argv[0]);
+
+	if(!inet_aton(argv[1], &mask))
+		errx(1, "invalid template mask: %s", argv[1]);
+
+	MD5Init(&ctx);
+
+	if(data)
+	{
+		l = strlen(data);
+		MD5Update(&ctx, data, l);
+	}
+	else
+	{
+		l = md5_file(stdin, &ctx);
+	}
+
+	if(l > 0)
+	{
+		unsigned char md[MD5_DIGEST_LENGTH];
+		MD5Final(md, &ctx);
+		memcpy(&result, md, sizeof(result));
+	}
+
+	result.s_addr = result.s_addr & ~mask.s_addr;
+	result.s_addr = result.s_addr | (templ.s_addr & mask.s_addr);
+
+	printf("%s\n", inet_ntoa(result));
+
+	return 0;
+}