1 files changed, 81 insertions, 0 deletions
diff --git a/ipv6.c b/ipv6.c
new file mode 100644
index 0000000..6fc5861
--- /dev/null
+++ b/ipv6.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2019 Nikos Mavrogiannopoulos
+ * Copyright 1991-1997, 1999-2014 Free Software Foundation, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <assert.h>
+
+/* Adds the two IP addresses and places the output in ap. This is based
+ * on Niels Moeller's mini-gmp. */
+void ipv6_add(struct in6_addr *ap, const struct in6_addr *bp)
+{
+	int i;
+	uint8_t cy;
+
+	for (i = 15, cy = 0; i >= 0; i--) {
+		uint8_t a, b, r;
+		a = ap->s6_addr[i];
+		b = bp->s6_addr[i];
+		r = a + cy;
+		cy = (r < cy);
+		r += b;
+		cy += (r < b);
+		ap->s6_addr[i] = r;
+	}
+	return;
+}
+
+/* Sets the "bit" of the IPv6 address to one */
+void ipv6_or1(struct in6_addr *a, unsigned bit)
+{
+	unsigned byte = bit / 8;
+	unsigned shift = bit % 8;
+
+	assert(bit < 128);
+
+	a->s6_addr[15 - byte] |= 1 << shift;
+}
+
+/* Sets all bits below "bits" to one */
+void ipv6_orm(struct in6_addr *a, unsigned bits)
+{
+	int i;
+	unsigned bytes = bits / 8;
+
+	assert(bits < 128);
+
+	for (i = 0; i < bytes; i++)
+		a->s6_addr[15 - i] |= 0xff;
+
+	for (i = bytes * 8; i < bits; i++)
+		ipv6_or1(a, i);
+}
+
+/* Returns 1 if IP a is greater than IP b, 0 if equal, -1 if less */
+int ipv6_cmp(struct in6_addr *a, struct in6_addr *b)
+{
+	unsigned i;
+	for (i = 0; i < 16; i++) {
+		if (a->s6_addr[i] != b->s6_addr[i])
+			return a->s6_addr[i] > b->s6_addr[i] ? 1 : -1;
+	}
+	return 0;
+}