New NETMAP target in p-o-m, by Svenning Soerenson

diff --git a/extensions/.NETMAP-test b/extensions/.NETMAP-test
new file mode 100755 (executable)
index 0000000..386a51a
--- /dev/null
+++ b/extensions/.NETMAP-test
@@ -0,0 +1,2 @@
+#! /bin/sh
+[ -f $KERNEL_DIR/net/ipv4/netfilter/ipt_NETMAP.c ] && echo NETMAP

diff --git a/extensions/libipt_NETMAP.c b/extensions/libipt_NETMAP.c
new file mode 100644 (file)
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);
+}
+