extensions: add IPv6 SNAT extension

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/extensions/libip6t_SNAT.c b/extensions/libip6t_SNAT.c
new file mode 100644 (file)
index 0000000..307be70
--- /dev/null
+++ b/extensions/libip6t_SNAT.c
@@ -0,0 +1,247 @@
+/*
+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
+ *
+ * Based on Rusty Russell's IPv4 SNAT target. Development of IPv6 NAT
+ * funded by Astaro.
+ */
+
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <xtables.h>
+#include <iptables.h>
+#include <limits.h> /* INT_MAX in ip_tables.h */
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter/nf_nat.h>
+
+enum {
+       O_TO_SRC = 0,
+       O_RANDOM,
+       O_PERSISTENT,
+       O_X_TO_SRC,
+       F_TO_SRC   = 1 << O_TO_SRC,
+       F_RANDOM   = 1 << O_RANDOM,
+       F_X_TO_SRC = 1 << O_X_TO_SRC,
+};
+
+static void SNAT_help(void)
+{
+       printf(
+"SNAT target options:\n"
+" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
+"                              Address to map source to.\n"
+"[--random] [--persistent]\n");
+}
+
+static const struct xt_option_entry SNAT_opts[] = {
+       {.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
+        .flags = XTOPT_MAND | XTOPT_MULTI},
+       {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
+       {.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
+       XTOPT_TABLEEND,
+};
+
+/* Ranges expected in network order. */
+static void
+parse_to(const char *orig_arg, int portok, struct nf_nat_range *range)
+{
+       char *arg, *start, *end = NULL, *colon = NULL, *dash, *error;
+       const struct in6_addr *ip;
+
+       arg = strdup(orig_arg);
+       if (arg == NULL)
+               xtables_error(RESOURCE_PROBLEM, "strdup");
+
+       start = strchr(arg, '[');
+       if (start == NULL)
+               start = arg;
+       else {
+               start++;
+               end = strchr(start, ']');
+               if (end == NULL)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Invalid address format");
+
+               *end = '\0';
+               colon = strchr(end + 1, ':');
+       }
+
+       if (colon) {
+               int port;
+
+               if (!portok)
+                       xtables_error(PARAMETER_PROBLEM,
+                                  "Need TCP, UDP, SCTP or DCCP with port specification");
+
+               range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+
+               port = atoi(colon+1);
+               if (port <= 0 || port > 65535)
+                       xtables_error(PARAMETER_PROBLEM,
+                                  "Port `%s' not valid\n", colon+1);
+
+               error = strchr(colon+1, ':');
+               if (error)
+                       xtables_error(PARAMETER_PROBLEM,
+                                  "Invalid port:port syntax - use dash\n");
+
+               dash = strchr(colon, '-');
+               if (!dash) {
+                       range->min_proto.tcp.port
+                               = range->max_proto.tcp.port
+                               = htons(port);
+               } else {
+                       int maxport;
+
+                       maxport = atoi(dash + 1);
+                       if (maxport <= 0 || maxport > 65535)
+                               xtables_error(PARAMETER_PROBLEM,
+                                          "Port `%s' not valid\n", dash+1);
+                       if (maxport < port)
+                               /* People are stupid. */
+                               xtables_error(PARAMETER_PROBLEM,
+                                          "Port range `%s' funky\n", colon+1);
+                       range->min_proto.tcp.port = htons(port);
+                       range->max_proto.tcp.port = htons(maxport);
+               }
+               /* Starts with a colon? No IP info...*/
+               if (colon == arg) {
+                       free(arg);
+                       return;
+               }
+               *colon = '\0';
+       }
+
+       range->flags |= NF_NAT_RANGE_MAP_IPS;
+       dash = strchr(start, '-');
+       if (colon && dash && dash > colon)
+               dash = NULL;
+
+       if (dash)
+               *dash = '\0';
+
+       ip = xtables_numeric_to_ip6addr(start);
+       if (!ip)
+               xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+                             start);
+       range->min_addr.in6 = *ip;
+       if (dash) {
+               ip = xtables_numeric_to_ip6addr(dash + 1);
+               if (!ip)
+                       xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+                                     dash+1);
+               range->max_addr.in6 = *ip;
+       } else
+               range->max_addr = range->min_addr;
+
+       free(arg);
+       return;
+}
+
+static void SNAT_parse(struct xt_option_call *cb)
+{
+       const struct ip6t_entry *entry = cb->xt_entry;
+       struct nf_nat_range *range = cb->data;
+       int portok;
+
+       if (entry->ipv6.proto == IPPROTO_TCP ||
+           entry->ipv6.proto == IPPROTO_UDP ||
+           entry->ipv6.proto == IPPROTO_SCTP ||
+           entry->ipv6.proto == IPPROTO_DCCP ||
+           entry->ipv6.proto == IPPROTO_ICMP)
+               portok = 1;
+       else
+               portok = 0;
+
+       xtables_option_parse(cb);
+       switch (cb->entry->id) {
+       case O_TO_SRC:
+               if (cb->xflags & F_X_TO_SRC) {
+                       if (!kernel_version)
+                               get_kernel_version();
+                       if (kernel_version > LINUX_VERSION(2, 6, 10))
+                               xtables_error(PARAMETER_PROBLEM,
+                                          "SNAT: Multiple --to-source not supported");
+               }
+               parse_to(cb->arg, portok, range);
+               break;
+       case O_PERSISTENT:
+               range->flags |= NF_NAT_RANGE_PERSISTENT;
+               break;
+       }
+}
+
+static void SNAT_fcheck(struct xt_fcheck_call *cb)
+{
+       static const unsigned int f = F_TO_SRC | F_RANDOM;
+       struct nf_nat_range *range = cb->data;
+
+       if ((cb->xflags & f) == f)
+               range->flags |= NF_NAT_RANGE_PROTO_RANDOM;
+}
+
+static void print_range(const struct nf_nat_range *range)
+{
+       if (range->flags & NF_NAT_RANGE_MAP_IPS) {
+               if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
+                       printf("[");
+               printf("%s", xtables_ip6addr_to_numeric(&range->min_addr.in6));
+               if (memcmp(&range->min_addr, &range->max_addr,
+                          sizeof(range->min_addr)))
+                       printf("-%s", xtables_ip6addr_to_numeric(&range->max_addr.in6));
+               if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
+                       printf("]");
+       }
+       if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
+               printf(":");
+               printf("%hu", ntohs(range->min_proto.tcp.port));
+               if (range->max_proto.tcp.port != range->min_proto.tcp.port)
+                       printf("-%hu", ntohs(range->max_proto.tcp.port));
+       }
+}
+
+static void SNAT_print(const void *ip, const struct xt_entry_target *target,
+                       int numeric)
+{
+       const struct nf_nat_range *range = (const void *)target->data;
+
+       printf(" to:");
+       print_range(range);
+       if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
+               printf(" random");
+       if (range->flags & NF_NAT_RANGE_PERSISTENT)
+               printf(" persistent");
+}
+
+static void SNAT_save(const void *ip, const struct xt_entry_target *target)
+{
+       const struct nf_nat_range *range = (const void *)target->data;
+
+       printf(" --to-source ");
+       print_range(range);
+       if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
+               printf(" --random");
+       if (range->flags & NF_NAT_RANGE_PERSISTENT)
+               printf(" --persistent");
+}
+
+static struct xtables_target snat_tg_reg = {
+       .name           = "SNAT",
+       .version        = XTABLES_VERSION,
+       .family         = NFPROTO_IPV6,
+       .revision       = 1,
+       .size           = XT_ALIGN(sizeof(struct nf_nat_range)),
+       .userspacesize  = XT_ALIGN(sizeof(struct nf_nat_range)),
+       .help           = SNAT_help,
+       .x6_parse       = SNAT_parse,
+       .x6_fcheck      = SNAT_fcheck,
+       .print          = SNAT_print,
+       .save           = SNAT_save,
+       .x6_options     = SNAT_opts,
+};
+
+void _init(void)
+{
+       xtables_register_target(&snat_tg_reg);
+}