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326 lines
8.2 KiB
326 lines
8.2 KiB
#include <stdio.h>
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#include <netdb.h>
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#include <string.h>
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#include <stdlib.h>
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#include <xtables.h>
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#include <iptables.h>
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#include <limits.h> /* INT_MAX in ip_tables.h */
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter/nf_nat.h>
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enum {
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O_TO_SRC = 0,
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O_RANDOM,
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O_RANDOM_FULLY,
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O_PERSISTENT,
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O_X_TO_SRC,
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F_TO_SRC = 1 << O_TO_SRC,
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F_RANDOM = 1 << O_RANDOM,
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F_RANDOM_FULLY = 1 << O_RANDOM_FULLY,
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F_X_TO_SRC = 1 << O_X_TO_SRC,
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};
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/* Source NAT data consists of a multi-range, indicating where to map
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to. */
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struct ipt_natinfo
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{
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struct xt_entry_target t;
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struct nf_nat_ipv4_multi_range_compat mr;
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};
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static void SNAT_help(void)
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{
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printf(
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"SNAT target options:\n"
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" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
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" Address to map source to.\n"
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"[--random] [--random-fully] [--persistent]\n");
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}
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static const struct xt_option_entry SNAT_opts[] = {
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{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
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.flags = XTOPT_MAND | XTOPT_MULTI},
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{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
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{.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
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{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
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XTOPT_TABLEEND,
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};
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static struct ipt_natinfo *
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append_range(struct ipt_natinfo *info, const struct nf_nat_ipv4_range *range)
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{
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unsigned int size;
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/* One rangesize already in struct ipt_natinfo */
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size = XT_ALIGN(sizeof(*info) + info->mr.rangesize * sizeof(*range));
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info = realloc(info, size);
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if (!info)
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xtables_error(OTHER_PROBLEM, "Out of memory\n");
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info->t.u.target_size = size;
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info->mr.range[info->mr.rangesize] = *range;
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info->mr.rangesize++;
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return info;
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}
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/* Ranges expected in network order. */
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static struct xt_entry_target *
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parse_to(const char *orig_arg, int portok, struct ipt_natinfo *info)
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{
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struct nf_nat_ipv4_range range;
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char *arg, *colon, *dash, *error;
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const struct in_addr *ip;
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arg = strdup(orig_arg);
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if (arg == NULL)
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xtables_error(RESOURCE_PROBLEM, "strdup");
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memset(&range, 0, sizeof(range));
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colon = strchr(arg, ':');
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if (colon) {
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int port;
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if (!portok)
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xtables_error(PARAMETER_PROBLEM,
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"Need TCP, UDP, SCTP or DCCP with port specification");
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range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
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port = atoi(colon+1);
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if (port <= 0 || port > 65535)
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xtables_error(PARAMETER_PROBLEM,
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"Port `%s' not valid\n", colon+1);
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error = strchr(colon+1, ':');
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if (error)
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xtables_error(PARAMETER_PROBLEM,
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"Invalid port:port syntax - use dash\n");
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dash = strchr(colon, '-');
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if (!dash) {
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range.min.tcp.port
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= range.max.tcp.port
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= htons(port);
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} else {
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int maxport;
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maxport = atoi(dash + 1);
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if (maxport <= 0 || maxport > 65535)
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xtables_error(PARAMETER_PROBLEM,
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"Port `%s' not valid\n", dash+1);
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if (maxport < port)
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/* People are stupid. */
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xtables_error(PARAMETER_PROBLEM,
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"Port range `%s' funky\n", colon+1);
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range.min.tcp.port = htons(port);
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range.max.tcp.port = htons(maxport);
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}
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/* Starts with a colon? No IP info...*/
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if (colon == arg) {
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free(arg);
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return &(append_range(info, &range)->t);
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}
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*colon = '\0';
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}
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range.flags |= NF_NAT_RANGE_MAP_IPS;
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dash = strchr(arg, '-');
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if (colon && dash && dash > colon)
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dash = NULL;
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if (dash)
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*dash = '\0';
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ip = xtables_numeric_to_ipaddr(arg);
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if (!ip)
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xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
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arg);
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range.min_ip = ip->s_addr;
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if (dash) {
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ip = xtables_numeric_to_ipaddr(dash+1);
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if (!ip)
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xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
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dash+1);
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range.max_ip = ip->s_addr;
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} else
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range.max_ip = range.min_ip;
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free(arg);
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return &(append_range(info, &range)->t);
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}
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static void SNAT_parse(struct xt_option_call *cb)
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{
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const struct ipt_entry *entry = cb->xt_entry;
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struct ipt_natinfo *info = (void *)(*cb->target);
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int portok;
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if (entry->ip.proto == IPPROTO_TCP
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|| entry->ip.proto == IPPROTO_UDP
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|| entry->ip.proto == IPPROTO_SCTP
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|| entry->ip.proto == IPPROTO_DCCP
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|| entry->ip.proto == IPPROTO_ICMP)
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portok = 1;
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else
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portok = 0;
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xtables_option_parse(cb);
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switch (cb->entry->id) {
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case O_TO_SRC:
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if (cb->xflags & F_X_TO_SRC) {
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if (!kernel_version)
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get_kernel_version();
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if (kernel_version > LINUX_VERSION(2, 6, 10))
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xtables_error(PARAMETER_PROBLEM,
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"SNAT: Multiple --to-source not supported");
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}
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*cb->target = parse_to(cb->arg, portok, info);
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cb->xflags |= F_X_TO_SRC;
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break;
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case O_PERSISTENT:
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info->mr.range[0].flags |= NF_NAT_RANGE_PERSISTENT;
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break;
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}
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}
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static void SNAT_fcheck(struct xt_fcheck_call *cb)
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{
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static const unsigned int f = F_TO_SRC | F_RANDOM;
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static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY;
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struct nf_nat_ipv4_multi_range_compat *mr = cb->data;
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if ((cb->xflags & f) == f)
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mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM;
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if ((cb->xflags & r) == r)
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mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
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}
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static void print_range(const struct nf_nat_ipv4_range *r)
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{
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if (r->flags & NF_NAT_RANGE_MAP_IPS) {
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struct in_addr a;
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a.s_addr = r->min_ip;
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printf("%s", xtables_ipaddr_to_numeric(&a));
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if (r->max_ip != r->min_ip) {
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a.s_addr = r->max_ip;
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printf("-%s", xtables_ipaddr_to_numeric(&a));
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}
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}
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if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
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printf(":");
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printf("%hu", ntohs(r->min.tcp.port));
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if (r->max.tcp.port != r->min.tcp.port)
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printf("-%hu", ntohs(r->max.tcp.port));
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}
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}
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static void SNAT_print(const void *ip, const struct xt_entry_target *target,
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int numeric)
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{
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const struct ipt_natinfo *info = (const void *)target;
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unsigned int i = 0;
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printf(" to:");
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for (i = 0; i < info->mr.rangesize; i++) {
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print_range(&info->mr.range[i]);
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
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printf(" random");
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
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printf(" random-fully");
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if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
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printf(" persistent");
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}
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}
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static void SNAT_save(const void *ip, const struct xt_entry_target *target)
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{
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const struct ipt_natinfo *info = (const void *)target;
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unsigned int i = 0;
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for (i = 0; i < info->mr.rangesize; i++) {
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printf(" --to-source ");
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print_range(&info->mr.range[i]);
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
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printf(" --random");
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
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printf(" --random-fully");
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if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
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printf(" --persistent");
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}
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}
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static void print_range_xlate(const struct nf_nat_ipv4_range *r,
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struct xt_xlate *xl)
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{
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if (r->flags & NF_NAT_RANGE_MAP_IPS) {
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struct in_addr a;
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a.s_addr = r->min_ip;
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xt_xlate_add(xl, "%s", xtables_ipaddr_to_numeric(&a));
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if (r->max_ip != r->min_ip) {
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a.s_addr = r->max_ip;
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xt_xlate_add(xl, "-%s", xtables_ipaddr_to_numeric(&a));
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}
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}
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if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
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xt_xlate_add(xl, ":");
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xt_xlate_add(xl, "%hu", ntohs(r->min.tcp.port));
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if (r->max.tcp.port != r->min.tcp.port)
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xt_xlate_add(xl, "-%hu", ntohs(r->max.tcp.port));
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}
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}
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static int SNAT_xlate(struct xt_xlate *xl,
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const struct xt_xlate_tg_params *params)
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{
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const struct ipt_natinfo *info = (const void *)params->target;
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unsigned int i = 0;
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bool sep_need = false;
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const char *sep = " ";
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for (i = 0; i < info->mr.rangesize; i++) {
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xt_xlate_add(xl, "snat to ");
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print_range_xlate(&info->mr.range[i], xl);
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM) {
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xt_xlate_add(xl, " random");
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sep_need = true;
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}
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if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) {
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if (sep_need)
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sep = ",";
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xt_xlate_add(xl, "%sfully-random", sep);
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sep_need = true;
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}
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if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT) {
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if (sep_need)
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sep = ",";
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xt_xlate_add(xl, "%spersistent", sep);
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}
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}
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return 1;
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}
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static struct xtables_target snat_tg_reg = {
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.name = "SNAT",
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.version = XTABLES_VERSION,
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.family = NFPROTO_IPV4,
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.size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
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.userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
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.help = SNAT_help,
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.x6_parse = SNAT_parse,
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.x6_fcheck = SNAT_fcheck,
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.print = SNAT_print,
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.save = SNAT_save,
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.x6_options = SNAT_opts,
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.xlate = SNAT_xlate,
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};
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void _init(void)
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{
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xtables_register_target(&snat_tg_reg);
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}
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