tc/m_nat.c

   1 /*
   2  * m_nat.c              NAT module
   3  *
   4  *              This program is free software; you can distribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Herbert Xu <herbert@gondor.apana.org.au>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <syslog.h>
  17 #include <fcntl.h>
  18 #include <sys/socket.h>
  19 #include <netinet/in.h>
  20 #include <arpa/inet.h>
  21 #include <string.h>
  22 #include <dlfcn.h>
  23 #include "utils.h"
  24 #include "tc_util.h"
  25 #include <linux/tc_act/tc_nat.h>
  26
  27 static void
  28 explain(void)
  29 {
  30         fprintf(stderr, "Usage: ... nat NAT\n"
  31                         "NAT := DIRECTION OLD NEW\n"
  32                         "DIRECTION := { ingress | egress }\n"
  33                         "OLD := PREFIX\n"
  34                         "NEW := ADDRESS\n");
  35 }
  36
  37 static void
  38 usage(void)
  39 {
  40         explain();
  41         exit(-1);
  42 }
  43
  44 static int
  45 parse_nat_args(int *argc_p, char ***argv_p,struct tc_nat *sel)
  46 {
  47         int argc = *argc_p;
  48         char **argv = *argv_p;
  49         inet_prefix addr;
  50
  51         if (argc <= 0)
  52                 return -1;
  53
  54         if (matches(*argv, "egress") == 0)
  55                 sel->flags |= TCA_NAT_FLAG_EGRESS;
  56         else if (matches(*argv, "ingress") != 0)
  57                 goto bad_val;
  58
  59         NEXT_ARG();
  60
  61         if (get_prefix_1(&addr, *argv, AF_INET))
  62                 goto bad_val;
  63
  64         sel->old_addr = addr.data[0];
  65         sel->mask = htonl(~0u << (32 - addr.bitlen));
  66
  67         NEXT_ARG();
  68
  69         if (get_prefix_1(&addr, *argv, AF_INET))
  70                 goto bad_val;
  71
  72         sel->new_addr = addr.data[0];
  73
  74         argc--;
  75         argv++;
  76
  77         *argc_p = argc;
  78         *argv_p = argv;
  79         return 0;
  80
  81 bad_val:
  82         return -1;
  83 }
  84
  85 static int
  86 parse_nat(struct action_util *a, int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
  87 {
  88         struct tc_nat sel;
  89
  90         int argc = *argc_p;
  91         char **argv = *argv_p;
  92         int ok = 0;
  93         struct rtattr *tail;
  94
  95         memset(&sel, 0, sizeof(sel));
  96
  97         while (argc > 0) {
  98                 if (matches(*argv, "nat") == 0) {
  99                         NEXT_ARG();
 100                         if (parse_nat_args(&argc, &argv, &sel)) {
 101                                 fprintf(stderr, "Illegal nat construct (%s) \n",
 102                                         *argv);
 103                                 explain();
 104                                 return -1;
 105                         }
 106                         ok++;
 107                         continue;
 108                 } else if (matches(*argv, "help") == 0) {
 109                         usage();
 110                 } else {
 111                         break;
 112                 }
 113
 114         }
 115
 116         if (!ok) {
 117                 explain();
 118                 return -1;
 119         }
 120
 121         if (argc) {
 122                 if (matches(*argv, "reclassify") == 0) {
 123                         sel.action = TC_ACT_RECLASSIFY;
 124                         argc--;
 125                         argv++;
 126                 } else if (matches(*argv, "pipe") == 0) {
 127                         sel.action = TC_ACT_PIPE;
 128                         argc--;
 129                         argv++;
 130                 } else if (matches(*argv, "drop") == 0 ||
 131                         matches(*argv, "shot") == 0) {
 132                         sel.action = TC_ACT_SHOT;
 133                         argc--;
 134                         argv++;
 135                 } else if (matches(*argv, "continue") == 0) {
 136                         sel.action = TC_ACT_UNSPEC;
 137                         argc--;
 138                         argv++;
 139                 } else if (matches(*argv, "pass") == 0) {
 140                         sel.action = TC_ACT_OK;
 141                         argc--;
 142                         argv++;
 143                 }
 144         }
 145
 146         if (argc) {
 147                 if (matches(*argv, "index") == 0) {
 148                         NEXT_ARG();
 149                         if (get_u32(&sel.index, *argv, 10)) {
 150                                 fprintf(stderr, "Pedit: Illegal \"index\"\n");
 151                                 return -1;
 152                         }
 153                         argc--;
 154                         argv++;
 155                 }
 156         }
 157
 158         tail = NLMSG_TAIL(n);
 159         addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 160         addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
 161         tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
 162
 163         *argc_p = argc;
 164         *argv_p = argv;
 165         return 0;
 166 }
 167
 168 static int
 169 print_nat(struct action_util *au,FILE * f, struct rtattr *arg)
 170 {
 171         struct tc_nat *sel;
 172         struct rtattr *tb[TCA_NAT_MAX + 1];
 173         char buf1[256];
 174         char buf2[256];
 175         SPRINT_BUF(buf3);
 176         int len;
 177
 178         if (arg == NULL)
 179                 return -1;
 180
 181         parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
 182
 183         if (tb[TCA_NAT_PARMS] == NULL) {
 184                 fprintf(f, "[NULL nat parameters]");
 185                 return -1;
 186         }
 187         sel = RTA_DATA(tb[TCA_NAT_PARMS]);
 188
 189         len = ffs(sel->mask);
 190         len = len ? 33 - len : 0;
 191
 192         fprintf(f, " nat %s %s/%d %s %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
 193                                           "egress" : "ingress",
 194                 format_host(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
 195                 len,
 196                 format_host(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)),
 197                 action_n2a(sel->action, buf3, sizeof (buf3)));
 198
 199         if (show_stats) {
 200                 if (tb[TCA_NAT_TM]) {
 201                         struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
 202                         print_tm(f,tm);
 203                 }
 204         }
 205
 206         return 0;
 207 }
 208
 209 struct action_util nat_action_util = {
 210         .id = "nat",
 211         .parse_aopt = parse_nat,
 212         .print_aopt = print_nat,
 213 };