1/* Shared library add-on to iptables to add simple non load-balancing SNAT support. */ 2#include <stdio.h> 3#include <netdb.h> 4#include <string.h> 5#include <stdlib.h> 6#include <getopt.h> 7#include <iptables.h> 8#include <linux/netfilter_ipv4/ip_tables.h> 9#include <linux/netfilter/nf_nat.h> 10/* For 64bit kernel / 32bit userspace */ 11#include "../include/linux/netfilter_ipv4/ipt_SAME.h" 12 13/* Function which prints out usage message. */ 14static void 15help(void) 16{ 17 printf( 18"SAME v%s options:\n" 19" --to <ipaddr>-<ipaddr>\n" 20" Addresses to map source to.\n" 21" May be specified more than\n" 22" once for multiple ranges.\n" 23" --nodst\n" 24" Don't use destination-ip in\n" 25" source selection\n" 26" --random\n" 27" Randomize source port\n" 28, 29IPTABLES_VERSION); 30} 31 32static struct option opts[] = { 33 { "to", 1, 0, '1' }, 34 { "nodst", 0, 0, '2'}, 35 { "random", 0, 0, '3' }, 36 { 0 } 37}; 38 39/* Initialize the target. */ 40static void 41init(struct ipt_entry_target *t, unsigned int *nfcache) 42{ 43 struct ipt_same_info *mr = (struct ipt_same_info *)t->data; 44 45 /* Set default to 0 */ 46 mr->rangesize = 0; 47 mr->info = 0; 48 mr->ipnum = 0; 49 50} 51 52/* Parses range of IPs */ 53static void 54parse_to(char *arg, struct ip_nat_range *range) 55{ 56 char *dash; 57 struct in_addr *ip; 58 59 range->flags |= IP_NAT_RANGE_MAP_IPS; 60 dash = strchr(arg, '-'); 61 62 if (dash) 63 *dash = '\0'; 64 65 ip = dotted_to_addr(arg); 66 if (!ip) 67 exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n", 68 arg); 69 range->min_ip = ip->s_addr; 70 71 if (dash) { 72 ip = dotted_to_addr(dash+1); 73 if (!ip) 74 exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n", 75 dash+1); 76 } 77 range->max_ip = ip->s_addr; 78 if (dash) 79 if (range->min_ip > range->max_ip) 80 exit_error(PARAMETER_PROBLEM, "Bad IP range `%s-%s'\n", 81 arg, dash+1); 82} 83 84#define IPT_SAME_OPT_TO 0x01 85#define IPT_SAME_OPT_NODST 0x02 86#define IPT_SAME_OPT_RANDOM 0x04 87 88/* Function which parses command options; returns true if it 89 ate an option */ 90static int 91parse(int c, char **argv, int invert, unsigned int *flags, 92 const struct ipt_entry *entry, 93 struct ipt_entry_target **target) 94{ 95 struct ipt_same_info *mr 96 = (struct ipt_same_info *)(*target)->data; 97 int count; 98 99 switch (c) { 100 case '1': 101 if (mr->rangesize == IPT_SAME_MAX_RANGE) 102 exit_error(PARAMETER_PROBLEM, 103 "Too many ranges specified, maximum " 104 "is %i ranges.\n", 105 IPT_SAME_MAX_RANGE); 106 if (check_inverse(optarg, &invert, NULL, 0)) 107 exit_error(PARAMETER_PROBLEM, 108 "Unexpected `!' after --to"); 109 110 parse_to(optarg, &mr->range[mr->rangesize]); 111 /* WTF do we need this for? */ 112 if (*flags & IPT_SAME_OPT_RANDOM) 113 mr->range[mr->rangesize].flags 114 |= IP_NAT_RANGE_PROTO_RANDOM; 115 mr->rangesize++; 116 *flags |= IPT_SAME_OPT_TO; 117 break; 118 119 case '2': 120 if (*flags & IPT_SAME_OPT_NODST) 121 exit_error(PARAMETER_PROBLEM, 122 "Can't specify --nodst twice"); 123 124 mr->info |= IPT_SAME_NODST; 125 *flags |= IPT_SAME_OPT_NODST; 126 break; 127 128 case '3': 129 *flags |= IPT_SAME_OPT_RANDOM; 130 for (count=0; count < mr->rangesize; count++) 131 mr->range[count].flags |= IP_NAT_RANGE_PROTO_RANDOM; 132 break; 133 134 default: 135 return 0; 136 } 137 138 return 1; 139} 140 141/* Final check; need --to. */ 142static void final_check(unsigned int flags) 143{ 144 if (!(flags & IPT_SAME_OPT_TO)) 145 exit_error(PARAMETER_PROBLEM, 146 "SAME needs --to"); 147} 148 149/* Prints out the targinfo. */ 150static void 151print(const struct ipt_ip *ip, 152 const struct ipt_entry_target *target, 153 int numeric) 154{ 155 int count; 156 struct ipt_same_info *mr 157 = (struct ipt_same_info *)target->data; 158 int random = 0; 159 160 printf("same:"); 161 162 for (count = 0; count < mr->rangesize; count++) { 163 struct ip_nat_range *r = &mr->range[count]; 164 struct in_addr a; 165 166 a.s_addr = r->min_ip; 167 168 printf("%s", addr_to_dotted(&a)); 169 a.s_addr = r->max_ip; 170 171 if (r->min_ip == r->max_ip) 172 printf(" "); 173 else 174 printf("-%s ", addr_to_dotted(&a)); 175 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM) 176 random = 1; 177 } 178 179 if (mr->info & IPT_SAME_NODST) 180 printf("nodst "); 181 182 if (random) 183 printf("random "); 184} 185 186/* Saves the union ipt_targinfo in parsable form to stdout. */ 187static void 188save(const struct ipt_ip *ip, const struct ipt_entry_target *target) 189{ 190 int count; 191 struct ipt_same_info *mr 192 = (struct ipt_same_info *)target->data; 193 int random = 0; 194 195 for (count = 0; count < mr->rangesize; count++) { 196 struct ip_nat_range *r = &mr->range[count]; 197 struct in_addr a; 198 199 a.s_addr = r->min_ip; 200 printf("--to %s", addr_to_dotted(&a)); 201 a.s_addr = r->max_ip; 202 203 if (r->min_ip == r->max_ip) 204 printf(" "); 205 else 206 printf("-%s ", addr_to_dotted(&a)); 207 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM) 208 random = 1; 209 } 210 211 if (mr->info & IPT_SAME_NODST) 212 printf("--nodst "); 213 214 if (random) 215 printf("--random "); 216} 217 218static struct iptables_target same = { 219 .next = NULL, 220 .name = "SAME", 221 .version = IPTABLES_VERSION, 222 .size = IPT_ALIGN(sizeof(struct ipt_same_info)), 223 .userspacesize = IPT_ALIGN(sizeof(struct ipt_same_info)), 224 .help = &help, 225 .init = &init, 226 .parse = &parse, 227 .final_check = &final_check, 228 .print = &print, 229 .save = &save, 230 .extra_opts = opts 231}; 232 233void _init(void) 234{ 235 register_target(&same); 236} 237