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- /* Same. Just like SNAT, only try to make the connections
- * between client A and server B always have the same source ip.
- *
- * (C) 2000 Paul `Rusty' Russell
- * (C) 2001 Martin Josefsson
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * 010320 Martin Josefsson <gandalf@wlug.westbo.se>
- * * copied ipt_BALANCE.c to ipt_SAME.c and changed a few things.
- * 010728 Martin Josefsson <gandalf@wlug.westbo.se>
- * * added --nodst to not include destination-ip in new source
- * calculations.
- * * added some more sanity-checks.
- * 010729 Martin Josefsson <gandalf@wlug.westbo.se>
- * * fixed a buggy if-statement in same_check(), should have
- * used ntohl() but didn't.
- * * added support for multiple ranges. IPT_SAME_MAX_RANGE is
- * defined in linux/include/linux/netfilter_ipv4/ipt_SAME.h
- * and is currently set to 10.
- * * added support for 1-address range, nice to have now that
- * we have multiple ranges.
- */
- #include <linux/types.h>
- #include <linux/ip.h>
- #include <linux/timer.h>
- #include <linux/module.h>
- #include <linux/netfilter.h>
- #include <linux/netdevice.h>
- #include <linux/if.h>
- #include <linux/inetdevice.h>
- #include <net/protocol.h>
- #include <net/checksum.h>
- #include <linux/netfilter_ipv4.h>
- #include <linux/netfilter/x_tables.h>
- #ifdef CONFIG_NF_NAT_NEEDED
- #include <net/netfilter/nf_nat_rule.h>
- #else
- #include <linux/netfilter_ipv4/ip_nat_rule.h>
- #endif
- #include <linux/netfilter_ipv4/ipt_SAME.h>
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("Martin Josefsson <gandalf@wlug.westbo.se>");
- MODULE_DESCRIPTION("iptables special SNAT module for consistent sourceip");
- #if 0
- #define DEBUGP printk
- #else
- #define DEBUGP(format, args...)
- #endif
- static int
- same_check(const char *tablename,
- const void *e,
- const struct xt_target *target,
- void *targinfo,
- unsigned int hook_mask)
- {
- unsigned int count, countess, rangeip, index = 0;
- struct ipt_same_info *mr = targinfo;
- mr->ipnum = 0;
- if (mr->rangesize < 1) {
- DEBUGP("same_check: need at least one dest range.\n");
- return 0;
- }
- if (mr->rangesize > IPT_SAME_MAX_RANGE) {
- DEBUGP("same_check: too many ranges specified, maximum "
- "is %u ranges\n",
- IPT_SAME_MAX_RANGE);
- return 0;
- }
- for (count = 0; count < mr->rangesize; count++) {
- if (ntohl(mr->range[count].min_ip) >
- ntohl(mr->range[count].max_ip)) {
- DEBUGP("same_check: min_ip is larger than max_ip in "
- "range `%u.%u.%u.%u-%u.%u.%u.%u'.\n",
- NIPQUAD(mr->range[count].min_ip),
- NIPQUAD(mr->range[count].max_ip));
- return 0;
- }
- if (!(mr->range[count].flags & IP_NAT_RANGE_MAP_IPS)) {
- DEBUGP("same_check: bad MAP_IPS.\n");
- return 0;
- }
- rangeip = (ntohl(mr->range[count].max_ip) -
- ntohl(mr->range[count].min_ip) + 1);
- mr->ipnum += rangeip;
- DEBUGP("same_check: range %u, ipnum = %u\n", count, rangeip);
- }
- DEBUGP("same_check: total ipaddresses = %u\n", mr->ipnum);
- mr->iparray = kmalloc((sizeof(u_int32_t) * mr->ipnum), GFP_KERNEL);
- if (!mr->iparray) {
- DEBUGP("same_check: Couldn't allocate %u bytes "
- "for %u ipaddresses!\n",
- (sizeof(u_int32_t) * mr->ipnum), mr->ipnum);
- return 0;
- }
- DEBUGP("same_check: Allocated %u bytes for %u ipaddresses.\n",
- (sizeof(u_int32_t) * mr->ipnum), mr->ipnum);
- for (count = 0; count < mr->rangesize; count++) {
- for (countess = ntohl(mr->range[count].min_ip);
- countess <= ntohl(mr->range[count].max_ip);
- countess++) {
- mr->iparray[index] = countess;
- DEBUGP("same_check: Added ipaddress `%u.%u.%u.%u' "
- "in index %u.\n",
- HIPQUAD(countess), index);
- index++;
- }
- }
- return 1;
- }
- static void
- same_destroy(const struct xt_target *target, void *targinfo)
- {
- struct ipt_same_info *mr = targinfo;
- kfree(mr->iparray);
- DEBUGP("same_destroy: Deallocated %u bytes for %u ipaddresses.\n",
- (sizeof(u_int32_t) * mr->ipnum), mr->ipnum);
- }
- static unsigned int
- same_target(struct sk_buff **pskb,
- const struct net_device *in,
- const struct net_device *out,
- unsigned int hooknum,
- const struct xt_target *target,
- const void *targinfo)
- {
- struct ip_conntrack *ct;
- enum ip_conntrack_info ctinfo;
- u_int32_t tmpip, aindex;
- __be32 new_ip;
- const struct ipt_same_info *same = targinfo;
- struct ip_nat_range newrange;
- const struct ip_conntrack_tuple *t;
- IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
- hooknum == NF_IP_POST_ROUTING);
- ct = ip_conntrack_get(*pskb, &ctinfo);
- t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
- /* Base new source on real src ip and optionally dst ip,
- giving some hope for consistency across reboots.
- Here we calculate the index in same->iparray which
- holds the ipaddress we should use */
- #ifdef CONFIG_NF_NAT_NEEDED
- tmpip = ntohl(t->src.u3.ip);
- if (!(same->info & IPT_SAME_NODST))
- tmpip += ntohl(t->dst.u3.ip);
- #else
- tmpip = ntohl(t->src.ip);
- if (!(same->info & IPT_SAME_NODST))
- tmpip += ntohl(t->dst.ip);
- #endif
- aindex = tmpip % same->ipnum;
- new_ip = htonl(same->iparray[aindex]);
- DEBUGP("ipt_SAME: src=%u.%u.%u.%u dst=%u.%u.%u.%u, "
- "new src=%u.%u.%u.%u\n",
- NIPQUAD(t->src.ip), NIPQUAD(t->dst.ip),
- NIPQUAD(new_ip));
- /* Transfer from original range. */
- newrange = ((struct ip_nat_range)
- { same->range[0].flags, new_ip, new_ip,
- /* FIXME: Use ports from correct range! */
- same->range[0].min, same->range[0].max });
- /* Hand modified range to generic setup. */
- return ip_nat_setup_info(ct, &newrange, hooknum);
- }
- static struct xt_target same_reg = {
- .name = "SAME",
- .family = AF_INET,
- .target = same_target,
- .targetsize = sizeof(struct ipt_same_info),
- .table = "nat",
- .hooks = (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_POST_ROUTING),
- .checkentry = same_check,
- .destroy = same_destroy,
- .me = THIS_MODULE,
- };
- static int __init ipt_same_init(void)
- {
- return xt_register_target(&same_reg);
- }
- static void __exit ipt_same_fini(void)
- {
- xt_unregister_target(&same_reg);
- }
- module_init(ipt_same_init);
- module_exit(ipt_same_fini);
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