Marc Boucher | e6869a8 | 2000-03-20 06:03:29 +0000 | [diff] [blame] | 1 | /* Shared library add-on to iptables to add source-NAT 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_ipv4/ip_nat_rule.h> |
| 10 | |
| 11 | /* Source NAT data consists of a multi-range, indicating where to map |
| 12 | to. */ |
| 13 | struct ipt_natinfo |
| 14 | { |
| 15 | struct ipt_entry_target t; |
| 16 | struct ip_nat_multi_range mr; |
| 17 | }; |
| 18 | |
| 19 | /* Function which prints out usage message. */ |
| 20 | static void |
| 21 | help(void) |
| 22 | { |
| 23 | printf( |
| 24 | "SNAT v%s options:\n" |
| 25 | " --to-source <ipaddr>[-<ipaddr>][:port-port]\n" |
| 26 | " Address to map source to.\n" |
| 27 | " (You can use this more than once)\n\n", |
| 28 | NETFILTER_VERSION); |
| 29 | } |
| 30 | |
| 31 | static struct option opts[] = { |
| 32 | { "to-source", 1, 0, '1' }, |
| 33 | { 0 } |
| 34 | }; |
| 35 | |
| 36 | /* Initialize the target. */ |
| 37 | static void |
| 38 | init(struct ipt_entry_target *t, unsigned int *nfcache) |
| 39 | { |
| 40 | /* Can't cache this */ |
| 41 | *nfcache |= NFC_UNKNOWN; |
| 42 | } |
| 43 | |
| 44 | static struct ipt_natinfo * |
| 45 | append_range(struct ipt_natinfo *info, const struct ip_nat_range *range) |
| 46 | { |
| 47 | unsigned int size; |
| 48 | |
| 49 | /* One rangesize already in struct ipt_natinfo */ |
| 50 | size = IPT_ALIGN(sizeof(*info) + info->mr.rangesize * sizeof(*range)); |
| 51 | |
| 52 | info = realloc(info, size); |
| 53 | if (!info) |
| 54 | exit_error(OTHER_PROBLEM, "Out of memory\n"); |
| 55 | |
Rusty Russell | 228e98d | 2000-04-27 10:28:06 +0000 | [diff] [blame] | 56 | info->t.u.target_size = size; |
Marc Boucher | e6869a8 | 2000-03-20 06:03:29 +0000 | [diff] [blame] | 57 | info->mr.range[info->mr.rangesize] = *range; |
| 58 | info->mr.rangesize++; |
| 59 | |
| 60 | return info; |
| 61 | } |
| 62 | |
| 63 | /* Ranges expected in network order. */ |
| 64 | static struct ipt_entry_target * |
| 65 | parse_to(char *arg, int portok, struct ipt_natinfo *info) |
| 66 | { |
| 67 | struct ip_nat_range range; |
| 68 | char *colon, *dash; |
| 69 | struct in_addr *ip; |
| 70 | |
| 71 | memset(&range, 0, sizeof(range)); |
| 72 | colon = strchr(arg, ':'); |
| 73 | |
| 74 | if (colon) { |
| 75 | int port; |
| 76 | |
| 77 | if (!portok) |
| 78 | exit_error(PARAMETER_PROBLEM, |
| 79 | "Need TCP or UDP with port specification"); |
| 80 | |
| 81 | range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED; |
| 82 | |
| 83 | port = atoi(colon+1); |
| 84 | if (port == 0 || port > 65535) |
| 85 | exit_error(PARAMETER_PROBLEM, |
| 86 | "Port `%s' not valid\n", colon+1); |
| 87 | |
| 88 | dash = strchr(colon, '-'); |
| 89 | if (!dash) { |
| 90 | range.min.tcp.port |
| 91 | = range.max.tcp.port |
| 92 | = htons(port); |
| 93 | } else { |
| 94 | int maxport; |
| 95 | |
| 96 | maxport = atoi(dash + 1); |
| 97 | if (maxport == 0 || maxport > 65535) |
| 98 | exit_error(PARAMETER_PROBLEM, |
| 99 | "Port `%s' not valid\n", dash+1); |
| 100 | if (maxport < port) |
| 101 | /* People are stupid. */ |
| 102 | exit_error(PARAMETER_PROBLEM, |
| 103 | "Port range `%s' funky\n", colon+1); |
| 104 | range.min.tcp.port = htons(port); |
| 105 | range.max.tcp.port = htons(maxport); |
| 106 | } |
| 107 | /* Starts with a colon? No IP info...*/ |
| 108 | if (colon == arg) |
| 109 | return &(append_range(info, &range)->t); |
| 110 | *colon = '\0'; |
| 111 | } |
| 112 | |
| 113 | range.flags |= IP_NAT_RANGE_MAP_IPS; |
| 114 | dash = strchr(arg, '-'); |
| 115 | if (colon && dash && dash > colon) |
| 116 | dash = NULL; |
| 117 | |
| 118 | if (dash) |
| 119 | *dash = '\0'; |
| 120 | |
| 121 | ip = dotted_to_addr(arg); |
| 122 | if (!ip) |
| 123 | exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n", |
| 124 | arg); |
| 125 | range.min_ip = ip->s_addr; |
| 126 | if (dash) { |
| 127 | ip = dotted_to_addr(dash+1); |
| 128 | if (!ip) |
| 129 | exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n", |
| 130 | dash+1); |
| 131 | range.max_ip = ip->s_addr; |
| 132 | } else |
| 133 | range.max_ip = range.min_ip; |
| 134 | |
| 135 | return &(append_range(info, &range)->t); |
| 136 | } |
| 137 | |
| 138 | /* Function which parses command options; returns true if it |
| 139 | ate an option */ |
| 140 | static int |
| 141 | parse(int c, char **argv, int invert, unsigned int *flags, |
| 142 | const struct ipt_entry *entry, |
| 143 | struct ipt_entry_target **target) |
| 144 | { |
| 145 | struct ipt_natinfo *info = (void *)*target; |
| 146 | int portok; |
| 147 | |
| 148 | if (entry->ip.proto == IPPROTO_TCP |
| 149 | || entry->ip.proto == IPPROTO_UDP) |
| 150 | portok = 1; |
| 151 | else |
| 152 | portok = 0; |
| 153 | |
| 154 | switch (c) { |
| 155 | case '1': |
| 156 | if (check_inverse(optarg, &invert)) |
| 157 | exit_error(PARAMETER_PROBLEM, |
| 158 | "Unexpected `!' after --to-source"); |
| 159 | |
| 160 | *target = parse_to(optarg, portok, info); |
| 161 | *flags = 1; |
| 162 | return 1; |
| 163 | |
| 164 | default: |
| 165 | return 0; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /* Final check; must have specfied --to-source. */ |
| 170 | static void final_check(unsigned int flags) |
| 171 | { |
| 172 | if (!flags) |
| 173 | exit_error(PARAMETER_PROBLEM, |
| 174 | "You must specify --to-source"); |
| 175 | } |
| 176 | |
| 177 | static void print_range(const struct ip_nat_range *r) |
| 178 | { |
| 179 | if (r->flags & IP_NAT_RANGE_MAP_IPS) { |
| 180 | struct in_addr a; |
| 181 | |
| 182 | a.s_addr = r->min_ip; |
| 183 | printf("%s", addr_to_dotted(&a)); |
| 184 | if (r->max_ip != r->min_ip) { |
| 185 | a.s_addr = r->max_ip; |
| 186 | printf("-%s", addr_to_dotted(&a)); |
| 187 | } |
| 188 | } |
| 189 | if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) { |
| 190 | printf(":"); |
| 191 | printf("%hu", ntohs(r->min.tcp.port)); |
| 192 | if (r->max.tcp.port != r->min.tcp.port) |
| 193 | printf("-%hu", ntohs(r->max.tcp.port)); |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | /* Prints out the targinfo. */ |
| 198 | static void |
| 199 | print(const struct ipt_ip *ip, |
| 200 | const struct ipt_entry_target *target, |
| 201 | int numeric) |
| 202 | { |
| 203 | struct ipt_natinfo *info = (void *)target; |
| 204 | unsigned int i = 0; |
| 205 | |
| 206 | printf("to:"); |
| 207 | for (i = 0; i < info->mr.rangesize; i++) { |
| 208 | print_range(&info->mr.range[i]); |
| 209 | printf(" "); |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | /* Saves the union ipt_targinfo in parsable form to stdout. */ |
| 214 | static void |
| 215 | save(const struct ipt_ip *ip, const struct ipt_entry_target *target) |
| 216 | { |
| 217 | struct ipt_natinfo *info = (void *)target; |
| 218 | unsigned int i = 0; |
| 219 | |
| 220 | for (i = 0; i < info->mr.rangesize; i++) { |
| 221 | printf("--to-source "); |
| 222 | print_range(&info->mr.range[i]); |
| 223 | printf(" "); |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | struct iptables_target snat |
| 228 | = { NULL, |
| 229 | "SNAT", |
| 230 | NETFILTER_VERSION, |
Rusty Russell | 73f72f5 | 2000-07-03 10:17:57 +0000 | [diff] [blame] | 231 | IPT_ALIGN(sizeof(struct ip_nat_multi_range)), |
| 232 | IPT_ALIGN(sizeof(struct ip_nat_multi_range)), |
Marc Boucher | e6869a8 | 2000-03-20 06:03:29 +0000 | [diff] [blame] | 233 | &help, |
| 234 | &init, |
| 235 | &parse, |
| 236 | &final_check, |
| 237 | &print, |
| 238 | &save, |
| 239 | opts |
| 240 | }; |
| 241 | |
| 242 | void _init(void) |
| 243 | { |
| 244 | register_target(&snat); |
| 245 | } |