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-rw-r--r--src/openvpn/clinat.c269
1 files changed, 269 insertions, 0 deletions
diff --git a/src/openvpn/clinat.c b/src/openvpn/clinat.c
new file mode 100644
index 0000000..af75fc9
--- /dev/null
+++ b/src/openvpn/clinat.c
@@ -0,0 +1,269 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ * 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.
+ *
+ * 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 (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CLIENT_NAT)
+
+#include "clinat.h"
+#include "proto.h"
+#include "socket.h"
+#include "memdbg.h"
+
+static bool
+add_entry(struct client_nat_option_list *dest,
+ const struct client_nat_entry *e)
+{
+ if (dest->n >= MAX_CLIENT_NAT)
+ {
+ msg (M_WARN, "WARNING: client-nat table overflow (max %d entries)", MAX_CLIENT_NAT);
+ return false;
+ }
+ else
+ {
+ dest->entries[dest->n++] = *e;
+ return true;
+ }
+}
+
+void
+print_client_nat_list(const struct client_nat_option_list *list, int msglevel)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+
+ msg (msglevel, "*** CNAT list");
+ if (list)
+ {
+ for (i = 0; i < list->n; ++i)
+ {
+ const struct client_nat_entry *e = &list->entries[i];
+ msg (msglevel, " CNAT[%d] t=%d %s/%s/%s",
+ i,
+ e->type,
+ print_in_addr_t (e->network, IA_NET_ORDER, &gc),
+ print_in_addr_t (e->netmask, IA_NET_ORDER, &gc),
+ print_in_addr_t (e->foreign_network, IA_NET_ORDER, &gc));
+ }
+ }
+ gc_free (&gc);
+}
+
+struct client_nat_option_list *
+new_client_nat_list (struct gc_arena *gc)
+{
+ struct client_nat_option_list *ret;
+ ALLOC_OBJ_CLEAR_GC (ret, struct client_nat_option_list, gc);
+ return ret;
+}
+
+struct client_nat_option_list *
+clone_client_nat_option_list (const struct client_nat_option_list *src, struct gc_arena *gc)
+{
+ struct client_nat_option_list *ret;
+ ALLOC_OBJ_GC (ret, struct client_nat_option_list, gc);
+ *ret = *src;
+ return ret;
+}
+
+void
+copy_client_nat_option_list (struct client_nat_option_list *dest,
+ const struct client_nat_option_list *src)
+{
+ int i;
+ for (i = 0; i < src->n; ++i)
+ {
+ if (!add_entry(dest, &src->entries[i]))
+ break;
+ }
+}
+
+void
+add_client_nat_to_option_list (struct client_nat_option_list *dest,
+ const char *type,
+ const char *network,
+ const char *netmask,
+ const char *foreign_network,
+ int msglevel)
+{
+ struct client_nat_entry e;
+ bool ok;
+
+ if (!strcmp(type, "snat"))
+ e.type = CN_SNAT;
+ else if (!strcmp(type, "dnat"))
+ e.type = CN_DNAT;
+ else
+ {
+ msg(msglevel, "client-nat: type must be 'snat' or 'dnat'");
+ return;
+ }
+
+ e.network = getaddr(0, network, 0, &ok, NULL);
+ if (!ok)
+ {
+ msg(msglevel, "client-nat: bad network: %s", network);
+ return;
+ }
+ e.netmask = getaddr(0, netmask, 0, &ok, NULL);
+ if (!ok)
+ {
+ msg(msglevel, "client-nat: bad netmask: %s", netmask);
+ return;
+ }
+ e.foreign_network = getaddr(0, foreign_network, 0, &ok, NULL);
+ if (!ok)
+ {
+ msg(msglevel, "client-nat: bad foreign network: %s", foreign_network);
+ return;
+ }
+
+ add_entry(dest, &e);
+}
+
+#if 0
+static void
+print_checksum (struct openvpn_iphdr *iph, const char *prefix)
+{
+ uint16_t *sptr;
+ unsigned int sum = 0;
+ int i = 0;
+ for (sptr = (uint16_t *)iph; (uint8_t *)sptr < (uint8_t *)iph + sizeof(struct openvpn_iphdr); sptr++)
+ {
+ i += 1;
+ sum += *sptr;
+ }
+ msg (M_INFO, "** CKSUM[%d] %s %08x", i, prefix, sum);
+}
+#endif
+
+static void
+print_pkt (struct openvpn_iphdr *iph, const char *prefix, const int direction, const int msglevel)
+{
+ struct gc_arena gc = gc_new ();
+
+ char *dirstr = "???";
+ if (direction == CN_OUTGOING)
+ dirstr = "OUT";
+ else if (direction == CN_INCOMING)
+ dirstr = "IN";
+
+ msg(msglevel, "** CNAT %s %s %s -> %s",
+ dirstr,
+ prefix,
+ print_in_addr_t (iph->saddr, IA_NET_ORDER, &gc),
+ print_in_addr_t (iph->daddr, IA_NET_ORDER, &gc));
+
+ gc_free (&gc);
+}
+
+void
+client_nat_transform (const struct client_nat_option_list *list,
+ struct buffer *ipbuf,
+ const int direction)
+{
+ struct ip_tcp_udp_hdr *h = (struct ip_tcp_udp_hdr *) BPTR (ipbuf);
+ int i;
+ uint32_t addr, *addr_ptr;
+ const uint32_t *from, *to;
+ int accumulate = 0;
+ unsigned int amask;
+ unsigned int alog = 0;
+
+ if (check_debug_level (D_CLIENT_NAT))
+ print_pkt (&h->ip, "BEFORE", direction, D_CLIENT_NAT);
+
+ for (i = 0; i < list->n; ++i)
+ {
+ const struct client_nat_entry *e = &list->entries[i]; /* current NAT rule */
+ if (e->type ^ direction)
+ {
+ addr = *(addr_ptr = &h->ip.daddr);
+ amask = 2;
+ }
+ else
+ {
+ addr = *(addr_ptr = &h->ip.saddr);
+ amask = 1;
+ }
+ if (direction)
+ {
+ from = &e->foreign_network;
+ to = &e->network;
+ }
+ else
+ {
+ from = &e->network;
+ to = &e->foreign_network;
+ }
+
+ if (((addr & e->netmask) == *from) && !(amask & alog))
+ {
+ /* pre-adjust IP checksum */
+ ADD_CHECKSUM_32(accumulate, addr);
+
+ /* do NAT transform */
+ addr = (addr & ~e->netmask) | *to;
+
+ /* post-adjust IP checksum */
+ SUB_CHECKSUM_32(accumulate, addr);
+
+ /* write the modified address to packet */
+ *addr_ptr = addr;
+
+ /* mark as modified */
+ alog |= amask;
+ }
+ }
+ if (alog)
+ {
+ if (check_debug_level (D_CLIENT_NAT))
+ print_pkt (&h->ip, "AFTER", direction, D_CLIENT_NAT);
+
+ ADJUST_CHECKSUM(accumulate, h->ip.check);
+
+ if (h->ip.protocol == OPENVPN_IPPROTO_TCP)
+ {
+ if (BLEN(ipbuf) >= sizeof(struct openvpn_iphdr) + sizeof(struct openvpn_tcphdr))
+ {
+ ADJUST_CHECKSUM(accumulate, h->u.tcp.check);
+ }
+ }
+ else if (h->ip.protocol == OPENVPN_IPPROTO_UDP)
+ {
+ if (BLEN(ipbuf) >= sizeof(struct openvpn_iphdr) + sizeof(struct openvpn_udphdr))
+ {
+ ADJUST_CHECKSUM(accumulate, h->u.udp.check);
+ }
+ }
+ }
+}
+
+#endif
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