New NETMAP target in p-o-m, by Svenning Soerenson
diff --git a/extensions/libipt_NETMAP.c b/extensions/libipt_NETMAP.c
new file mode 100644
index 0000000..4cd7abc
--- /dev/null
+++ b/extensions/libipt_NETMAP.c
@@ -0,0 +1,201 @@
+/* Shared library add-on to iptables to add static NAT support.
+ Author: Svenning Soerensen <svenning@post5.tele.dk>
+*/
+
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <iptables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+
+#define MODULENAME "NETMAP"
+
+static struct option opts[] = {
+ { "to", 1, 0, '1' },
+ { 0 }
+};
+
+/* Function which prints out usage message. */
+static void
+help(void)
+{
+ printf(MODULENAME" v%s options:\n"
+ " --%s address[/mask]\n"
+ " Network address to map to.\n\n",
+ NETFILTER_VERSION, opts[0].name);
+}
+
+static u_int32_t
+bits2netmask(int bits)
+{
+ u_int32_t netmask, bm;
+
+ if (bits >= 32 || bits < 0)
+ return(~0);
+ for (netmask = 0, bm = 0x80000000; bits; bits--, bm >>= 1)
+ netmask |= bm;
+ return htonl(netmask);
+}
+
+static int
+netmask2bits(u_int32_t netmask)
+{
+ u_int32_t bm;
+ int bits;
+
+ netmask = ntohl(netmask);
+ for (bits = 0, bm = 0x80000000; netmask & bm; netmask <<= 1)
+ bits++;
+ if (netmask)
+ return -1; /* holes in netmask */
+ return bits;
+}
+
+/* Initialize the target. */
+static void
+init(struct ipt_entry_target *t, unsigned int *nfcache)
+{
+ struct ip_nat_multi_range *mr = (struct ip_nat_multi_range *)t->data;
+
+ /* Actually, it's 0, but it's ignored at the moment. */
+ mr->rangesize = 1;
+
+ /* Can't cache this */
+ *nfcache |= NFC_UNKNOWN;
+}
+
+/* Parses network address */
+static void
+parse_to(char *arg, struct ip_nat_range *range)
+{
+ char *slash;
+ struct in_addr *ip;
+ u_int32_t netmask;
+ int bits;
+
+ range->flags |= IP_NAT_RANGE_MAP_IPS;
+ slash = strchr(arg, '/');
+ if (slash)
+ *slash = '\0';
+
+ ip = dotted_to_addr(arg);
+ if (!ip)
+ exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
+ arg);
+ range->min_ip = ip->s_addr;
+ if (slash) {
+ if (strchr(slash+1, '.')) {
+ ip = dotted_to_addr(slash+1);
+ if (!ip)
+ exit_error(PARAMETER_PROBLEM, "Bad netmask `%s'\n",
+ slash+1);
+ netmask = ip->s_addr;
+ }
+ else {
+ if ((bits = string_to_number(slash+1, 0, 32)) == -1)
+ exit_error(PARAMETER_PROBLEM, "Bad netmask `%s'\n",
+ slash+1);
+ netmask = bits2netmask(bits);
+ }
+ /* Don't allow /0 (/1 is probably insane, too) */
+ if (netmask == 0)
+ exit_error(PARAMETER_PROBLEM, "Netmask needed\n");
+ }
+ else
+ netmask = ~0;
+
+ if (range->min_ip & ~netmask) {
+ if (slash)
+ *slash = '/';
+ exit_error(PARAMETER_PROBLEM, "Bad network address `%s'\n",
+ arg);
+ }
+ range->max_ip = range->min_ip | ~netmask;
+}
+
+/* Function which parses command options; returns true if it
+ ate an option */
+static int
+parse(int c, char **argv, int invert, unsigned int *flags,
+ const struct ipt_entry *entry,
+ struct ipt_entry_target **target)
+{
+ struct ip_nat_multi_range *mr
+ = (struct ip_nat_multi_range *)(*target)->data;
+
+ switch (c) {
+ case '1':
+ if (check_inverse(optarg, &invert))
+ exit_error(PARAMETER_PROBLEM,
+ "Unexpected `!' after --%s", opts[0].name);
+
+ parse_to(optarg, &mr->range[0]);
+ *flags = 1;
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+/* Final check; need --to */
+static void final_check(unsigned int flags)
+{
+ if (!flags)
+ exit_error(PARAMETER_PROBLEM,
+ MODULENAME" needs --%s", opts[0].name);
+}
+
+/* Prints out the targinfo. */
+static void
+print(const struct ipt_ip *ip,
+ const struct ipt_entry_target *target,
+ int numeric)
+{
+ struct ip_nat_multi_range *mr
+ = (struct ip_nat_multi_range *)target->data;
+ struct ip_nat_range *r = &mr->range[0];
+ struct in_addr a;
+ int bits;
+
+ a.s_addr = r->min_ip;
+ printf("%s", addr_to_dotted(&a));
+ a.s_addr = ~(r->min_ip ^ r->max_ip);
+ bits = netmask2bits(a.s_addr);
+ if (bits < 0)
+ printf("/%s", addr_to_dotted(&a));
+ else
+ printf("/%d", bits);
+}
+
+/* Saves the targinfo in parsable form to stdout. */
+static void
+save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
+{
+ printf("--%s ", opts[0].name);
+ print(ip, target, 0);
+}
+
+struct iptables_target target_module
+= { NULL,
+ MODULENAME,
+ NETFILTER_VERSION,
+ IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
+ IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
+ &help,
+ &init,
+ &parse,
+ &final_check,
+ &print,
+ &save,
+ opts
+};
+
+void _init(void)
+{
+ register_target(&target_module);
+}
+