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-rw-r--r--package/6rd/src/6rdcalc.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/package/6rd/src/6rdcalc.c b/package/6rd/src/6rdcalc.c
new file mode 100644
index 0000000000..56e07d255b
--- /dev/null
+++ b/package/6rd/src/6rdcalc.c
@@ -0,0 +1,126 @@
+/*
+ * Utility used to calculate the 6rd subnet.
+ *
+ * Copyright 2012, Stéphan Kochen <stephan@kochen.nl>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/errno.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#define INET_PREFIXSTRLEN (INET_ADDRSTRLEN+3)
+#define INET6_PREFIXSTRLEN (INET6_ADDRSTRLEN+4)
+
+static void print_usage()
+{
+ fprintf(stderr, "Usage: 6rdcalc <v6 prefix>/<mask> <v4 address>/<mask>\n");
+ exit(1);
+}
+
+static void print_error()
+{
+ fprintf(stderr, "%s", strerror(errno));
+ exit(1);
+}
+
+static void parse_str(int af, char *str, void *addr, unsigned long *mask)
+{
+ int ret;
+ char *slash;
+
+ /* Split the address at the slash. */
+ if ((slash = strchr(str, '/')) == NULL)
+ print_usage();
+ *slash = '\0';
+
+ /* Parse the address. */
+ if ((ret = inet_pton(af, str, addr)) != 1) {
+ if (ret == 0)
+ print_usage();
+ else
+ print_error();
+ }
+
+ /* Parse the mask. */
+ *mask = strtoul(slash+1, NULL, 10);
+ if ((af == AF_INET && *mask > 32) ||
+ (af == AF_INET6 && *mask > 128))
+ print_usage();
+}
+
+int main(int argc, const char **argv)
+{
+ char v6str[INET6_PREFIXSTRLEN], v4str[INET_PREFIXSTRLEN];
+ struct in6_addr v6;
+ struct in_addr v4;
+ unsigned long v6it, v4it, mask;
+ unsigned char *byte4, *byte6;
+ unsigned char bit4, bit6;
+
+ /* Check parameters. */
+ if (argc != 3)
+ print_usage();
+
+ /* Parse the v6 address. */
+ strncpy(v6str, argv[1], INET6_PREFIXSTRLEN);
+ v6str[INET6_PREFIXSTRLEN-1] = '\0';
+ parse_str(AF_INET6, v6str, &v6, &v6it);
+
+ /* Parse the v4 address */
+ strncpy(v4str, argv[2], INET_PREFIXSTRLEN);
+ v6str[INET_PREFIXSTRLEN-1] = '\0';
+ parse_str(AF_INET, v4str, &v4, &v4it);
+
+ /* Check if the combined mask is within bounds. */
+ mask = (32 - v4it) + v6it;
+ if (mask > 128)
+ print_usage();
+
+ /* Combine the addresses. */
+ while (v4it < 32) {
+ byte6 = (unsigned char *)(&v6.s6_addr) + (v6it >> 3);
+ byte4 = (unsigned char *)(&v4.s_addr) + (v4it >> 3);
+ bit6 = 128 >> (v6it & 0x07);
+ bit4 = 128 >> (v4it & 0x07);
+
+ if (*byte4 & bit4)
+ *byte6 |= bit6;
+ else
+ *byte6 &= ~bit6;
+
+ v4it++; v6it++;
+ }
+
+ /* Clear remaining bits. */
+ while (v6it < 128) {
+ byte6 = (unsigned char *)(&v6.s6_addr) + (v6it >> 2);
+ bit6 = 128 >> (v6it & 0x07);
+
+ *byte6 &= ~bit6;
+
+ v6it++;
+ }
+
+ /* Print the subnet prefix. */
+ if (inet_ntop(AF_INET6, &v6, v6str, sizeof(v6str)) == NULL)
+ print_error();
+ printf("%s/%lu\n", v6str, mask);
+ return 0;
+}