[NETFILTER]: nf_nat: add helpers for common NAT protocol operations

Add generic ->in_range and ->unique_tuple ops to avoid duplicating them
again and again for future NAT modules and save a few bytes of text:

net/ipv4/netfilter/nf_nat_proto_tcp.c:
  tcp_in_range     |  -62 (removed)
  tcp_unique_tuple | -259 # 271 -> 12, # inlines: 1 -> 0, size inlines: 7 -> 0
 2 functions changed, 321 bytes removed

net/ipv4/netfilter/nf_nat_proto_udp.c:
  udp_in_range     |  -62 (removed)
  udp_unique_tuple | -259 # 271 -> 12, # inlines: 1 -> 0, size inlines: 7 -> 0
 2 functions changed, 321 bytes removed

net/ipv4/netfilter/nf_nat_proto_gre.c:
  gre_in_range |  -62 (removed)
 1 function changed, 62 bytes removed

vmlinux:
 5 functions changed, 704 bytes removed

Signed-off-by: Patrick McHardy <kaber@trash.net>

5 files changed, 95 insertions, 141 deletions

diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 0c7dc78a62e9..e73d0eb9994a 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -10,7 +10,7 @@ nf_conntrack_ipv4-objs	+= nf_conntrack_l3proto_ipv4_compat.o
 endif
 endif
 
-nf_nat-objs             := nf_nat_core.o nf_nat_helper.o nf_nat_proto_unknown.o nf_nat_proto_tcp.o nf_nat_proto_udp.o nf_nat_proto_icmp.o
+nf_nat-objs             := nf_nat_core.o nf_nat_helper.o nf_nat_proto_unknown.o nf_nat_proto_common.o nf_nat_proto_tcp.o nf_nat_proto_udp.o nf_nat_proto_icmp.o
 iptable_nat-objs        := nf_nat_rule.o nf_nat_standalone.o
 
 # connection tracking
diff --git a/net/ipv4/netfilter/nf_nat_proto_common.c b/net/ipv4/netfilter/nf_nat_proto_common.c
new file mode 100644
index 000000000000..a124213fb9da
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_proto_common.c
@@ -0,0 +1,85 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * (C) 2008 Patrick McHardy <kaber@trash.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.
+ */
+
+#include <linux/types.h>
+#include <linux/random.h>
+#include <linux/ip.h>
+
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_nat_protocol.h>
+
+int nf_nat_proto_in_range(const struct nf_conntrack_tuple *tuple,
+                          enum nf_nat_manip_type maniptype,
+                          const union nf_conntrack_man_proto *min,
+                          const union nf_conntrack_man_proto *max)
+{
+        __be16 port;
+
+        if (maniptype == IP_NAT_MANIP_SRC)
+                port = tuple->src.u.all;
+        else
+                port = tuple->dst.u.all;
+
+        return ntohs(port) >= ntohs(min->all) &&
+               ntohs(port) <= ntohs(max->all);
+}
+EXPORT_SYMBOL_GPL(nf_nat_proto_in_range);
+
+int nf_nat_proto_unique_tuple(struct nf_conntrack_tuple *tuple,
+                              const struct nf_nat_range *range,
+                              enum nf_nat_manip_type maniptype,
+                              const struct nf_conn *ct,
+                              u_int16_t *rover)
+{
+        unsigned int range_size, min, i;
+        __be16 *portptr;
+
+        if (maniptype == IP_NAT_MANIP_SRC)
+                portptr = &tuple->src.u.all;
+        else
+                portptr = &tuple->dst.u.all;
+
+        /* If no range specified... */
+        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
+                /* If it's dst rewrite, can't change port */
+                if (maniptype == IP_NAT_MANIP_DST)
+                        return 0;
+
+                if (ntohs(*portptr) < 1024) {
+                        /* Loose convention: >> 512 is credential passing */
+                        if (ntohs(*portptr) < 512) {
+                                min = 1;
+                                range_size = 511 - min + 1;
+                        } else {
+                                min = 600;
+                                range_size = 1023 - min + 1;
+                        }
+                } else {
+                        min = 1024;
+                        range_size = 65535 - 1024 + 1;
+                }
+        } else {
+                min = ntohs(range->min.all);
+                range_size = ntohs(range->max.all) - min + 1;
+        }
+
+        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
+                *rover = net_random();
+
+        for (i = 0; i < range_size; i++, (*rover)++) {
+                *portptr = htons(min + *rover % range_size);
+                if (!nf_nat_used_tuple(tuple, ct))
+                        return 1;
+        }
+        return 0;
+}
+EXPORT_SYMBOL_GPL(nf_nat_proto_unique_tuple);
diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c
index a1e4da16da2e..87af63d9e692 100644
--- a/net/ipv4/netfilter/nf_nat_proto_gre.c
+++ b/net/ipv4/netfilter/nf_nat_proto_gre.c
@@ -36,24 +36,6 @@ MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
 MODULE_DESCRIPTION("Netfilter NAT protocol helper module for GRE");
 
-/* is key in given range between min and max */
-static int
-gre_in_range(const struct nf_conntrack_tuple *tuple,
-             enum nf_nat_manip_type maniptype,
-             const union nf_conntrack_man_proto *min,
-             const union nf_conntrack_man_proto *max)
-{
-        __be16 key;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                key = tuple->src.u.gre.key;
-        else
-                key = tuple->dst.u.gre.key;
-
-        return ntohs(key) >= ntohs(min->gre.key) &&
-               ntohs(key) <= ntohs(max->gre.key);
-}
-
 /* generate unique tuple ... */
 static int
 gre_unique_tuple(struct nf_conntrack_tuple *tuple,
@@ -140,7 +122,7 @@ static const struct nf_nat_protocol gre = {
         .protonum               = IPPROTO_GRE,
         .me                     = THIS_MODULE,
         .manip_pkt              = gre_manip_pkt,
-        .in_range               = gre_in_range,
+        .in_range               = nf_nat_proto_in_range,
         .unique_tuple           = gre_unique_tuple,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
         .range_to_nlattr        = nf_nat_port_range_to_nlattr,
diff --git a/net/ipv4/netfilter/nf_nat_proto_tcp.c b/net/ipv4/netfilter/nf_nat_proto_tcp.c
index ffd5d1589eca..f8c498fc24fd 100644
--- a/net/ipv4/netfilter/nf_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_tcp.c
@@ -8,7 +8,6 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
-#include <linux/random.h>
 #include <linux/ip.h>
 #include <linux/tcp.h>
 
@@ -19,22 +18,7 @@
 #include <net/netfilter/nf_nat_protocol.h>
 #include <net/netfilter/nf_nat_core.h>
 
-static int
-tcp_in_range(const struct nf_conntrack_tuple *tuple,
-             enum nf_nat_manip_type maniptype,
-             const union nf_conntrack_man_proto *min,
-             const union nf_conntrack_man_proto *max)
-{
-        __be16 port;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                port = tuple->src.u.tcp.port;
-        else
-                port = tuple->dst.u.tcp.port;
-
-        return ntohs(port) >= ntohs(min->tcp.port) &&
-               ntohs(port) <= ntohs(max->tcp.port);
-}
+static u_int16_t tcp_port_rover;
 
 static int
 tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
@@ -42,49 +26,8 @@ tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
                  enum nf_nat_manip_type maniptype,
                  const struct nf_conn *ct)
 {
-        static u_int16_t port;
-        __be16 *portptr;
-        unsigned int range_size, min, i;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                portptr = &tuple->src.u.tcp.port;
-        else
-                portptr = &tuple->dst.u.tcp.port;
-
-        /* If no range specified... */
-        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
-                /* If it's dst rewrite, can't change port */
-                if (maniptype == IP_NAT_MANIP_DST)
-                        return 0;
-
-                /* Map privileged onto privileged. */
-                if (ntohs(*portptr) < 1024) {
-                        /* Loose convention: >> 512 is credential passing */
-                        if (ntohs(*portptr)<512) {
-                                min = 1;
-                                range_size = 511 - min + 1;
-                        } else {
-                                min = 600;
-                                range_size = 1023 - min + 1;
-                        }
-                } else {
-                        min = 1024;
-                        range_size = 65535 - 1024 + 1;
-                }
-        } else {
-                min = ntohs(range->min.tcp.port);
-                range_size = ntohs(range->max.tcp.port) - min + 1;
-        }
-
-        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
-                port =  net_random();
-
-        for (i = 0; i < range_size; i++, port++) {
-                *portptr = htons(min + port % range_size);
-                if (!nf_nat_used_tuple(tuple, ct))
-                        return 1;
-        }
-        return 0;
+        return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
+                                         &tcp_port_rover);
 }
 
 static int
@@ -142,7 +85,7 @@ const struct nf_nat_protocol nf_nat_protocol_tcp = {
         .protonum               = IPPROTO_TCP,
         .me                     = THIS_MODULE,
         .manip_pkt              = tcp_manip_pkt,
-        .in_range               = tcp_in_range,
+        .in_range               = nf_nat_proto_in_range,
         .unique_tuple           = tcp_unique_tuple,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
         .range_to_nlattr        = nf_nat_port_range_to_nlattr,
diff --git a/net/ipv4/netfilter/nf_nat_proto_udp.c b/net/ipv4/netfilter/nf_nat_proto_udp.c
index 4b8f49910ff2..a182f5ac3177 100644
--- a/net/ipv4/netfilter/nf_nat_proto_udp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_udp.c
@@ -8,7 +8,6 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
-#include <linux/random.h>
 #include <linux/ip.h>
 #include <linux/udp.h>
 
@@ -18,22 +17,7 @@
 #include <net/netfilter/nf_nat_rule.h>
 #include <net/netfilter/nf_nat_protocol.h>
 
-static int
-udp_in_range(const struct nf_conntrack_tuple *tuple,
-             enum nf_nat_manip_type maniptype,
-             const union nf_conntrack_man_proto *min,
-             const union nf_conntrack_man_proto *max)
-{
-        __be16 port;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                port = tuple->src.u.udp.port;
-        else
-                port = tuple->dst.u.udp.port;
-
-        return ntohs(port) >= ntohs(min->udp.port) &&
-               ntohs(port) <= ntohs(max->udp.port);
-}
+static u_int16_t udp_port_rover;
 
 static int
 udp_unique_tuple(struct nf_conntrack_tuple *tuple,
@@ -41,48 +25,8 @@ udp_unique_tuple(struct nf_conntrack_tuple *tuple,
                  enum nf_nat_manip_type maniptype,
                  const struct nf_conn *ct)
 {
-        static u_int16_t port;
-        __be16 *portptr;
-        unsigned int range_size, min, i;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                portptr = &tuple->src.u.udp.port;
-        else
-                portptr = &tuple->dst.u.udp.port;
-
-        /* If no range specified... */
-        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
-                /* If it's dst rewrite, can't change port */
-                if (maniptype == IP_NAT_MANIP_DST)
-                        return 0;
-
-                if (ntohs(*portptr) < 1024) {
-                        /* Loose convention: >> 512 is credential passing */
-                        if (ntohs(*portptr)<512) {
-                                min = 1;
-                                range_size = 511 - min + 1;
-                        } else {
-                                min = 600;
-                                range_size = 1023 - min + 1;
-                        }
-                } else {
-                        min = 1024;
-                        range_size = 65535 - 1024 + 1;
-                }
-        } else {
-                min = ntohs(range->min.udp.port);
-                range_size = ntohs(range->max.udp.port) - min + 1;
-        }
-
-        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
-                port = net_random();
-
-        for (i = 0; i < range_size; i++, port++) {
-                *portptr = htons(min + port % range_size);
-                if (!nf_nat_used_tuple(tuple, ct))
-                        return 1;
-        }
-        return 0;
+        return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
+                                         &udp_port_rover);
 }
 
 static int
@@ -132,7 +76,7 @@ const struct nf_nat_protocol nf_nat_protocol_udp = {
         .protonum               = IPPROTO_UDP,
         .me                     = THIS_MODULE,
         .manip_pkt              = udp_manip_pkt,
-        .in_range               = udp_in_range,
+        .in_range               = nf_nat_proto_in_range,
         .unique_tuple           = udp_unique_tuple,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
         .range_to_nlattr        = nf_nat_port_range_to_nlattr,