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 <fcntl.h>
  17 #include <sys/socket.h>
  18 #include <netinet/in.h>
  19 #include <arpa/inet.h>
  20 #include <string.h>
  21 #include "utils.h"
  22 #include "tc_util.h"
  23 #include <linux/tc_act/tc_nat.h>
  24
  25 static void
  26 explain(void)
  27 {
  28         fprintf(stderr, "Usage: ... nat NAT\n"
  29                         "NAT := DIRECTION OLD NEW\n"
  30                         "DIRECTION := { ingress | egress }\n"
  31                         "OLD := PREFIX\n"
  32                         "NEW := ADDRESS\n");
  33 }
  34
  35 static void
  36 usage(void)
  37 {
  38         explain();
  39         exit(-1);
  40 }
  41
  42 static int
  43 parse_nat_args(int *argc_p, char ***argv_p, struct tc_nat *sel)
  44 {
  45         int argc = *argc_p;
  46         char **argv = *argv_p;
  47         inet_prefix addr;
  48
  49         if (argc <= 0)
  50                 return -1;
  51
  52         if (matches(*argv, "egress") == 0)
  53                 sel->flags |= TCA_NAT_FLAG_EGRESS;
  54         else if (matches(*argv, "ingress") != 0)
  55                 goto bad_val;
  56
  57         NEXT_ARG();
  58
  59         if (get_prefix_1(&addr, *argv, AF_INET))
  60                 goto bad_val;
  61
  62         sel->old_addr = addr.data[0];
  63         sel->mask = htonl(~0u << (32 - addr.bitlen));
  64
  65         NEXT_ARG();
  66
  67         if (get_prefix_1(&addr, *argv, AF_INET))
  68                 goto bad_val;
  69
  70         sel->new_addr = addr.data[0];
  71
  72         argc--;
  73         argv++;
  74
  75         *argc_p = argc;
  76         *argv_p = argv;
  77         return 0;
  78
  79 bad_val:
  80         return -1;
  81 }
  82
  83 static int
  84 parse_nat(struct action_util *a, int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
  85 {
  86         struct tc_nat sel = {};
  87
  88         int argc = *argc_p;
  89         char **argv = *argv_p;
  90         int ok = 0;
  91         struct rtattr *tail;
  92
  93         while (argc > 0) {
  94                 if (matches(*argv, "nat") == 0) {
  95                         NEXT_ARG();
  96                         if (parse_nat_args(&argc, &argv, &sel)) {
  97                                 fprintf(stderr, "Illegal nat construct (%s)\n",
  98                                         *argv);
  99                                 explain();
 100                                 return -1;
 101                         }
 102                         ok++;
 103                         continue;
 104                 } else if (matches(*argv, "help") == 0) {
 105                         usage();
 106                 } else {
 107                         break;
 108                 }
 109
 110         }
 111
 112         if (!ok) {
 113                 explain();
 114                 return -1;
 115         }
 116
 117         parse_action_control_dflt(&argc, &argv, &sel.action, false, TC_ACT_OK);
 118
 119         NEXT_ARG_FWD();
 120         if (argc) {
 121                 if (matches(*argv, "index") == 0) {
 122                         NEXT_ARG();
 123                         if (get_u32(&sel.index, *argv, 10)) {
 124                                 fprintf(stderr, "Nat: Illegal \"index\"\n");
 125                                 return -1;
 126                         }
 127                         argc--;
 128                         argv++;
 129                 }
 130         }
 131
 132         tail = NLMSG_TAIL(n);
 133         addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 134         addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
 135         tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
 136
 137         *argc_p = argc;
 138         *argv_p = argv;
 139         return 0;
 140 }
 141
 142 static int
 143 print_nat(struct action_util *au, FILE * f, struct rtattr *arg)
 144 {
 145         struct tc_nat *sel;
 146         struct rtattr *tb[TCA_NAT_MAX + 1];
 147         char buf1[256];
 148         char buf2[256];
 149
 150         int len;
 151
 152         if (arg == NULL)
 153                 return -1;
 154
 155         parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
 156
 157         if (tb[TCA_NAT_PARMS] == NULL) {
 158                 fprintf(f, "[NULL nat parameters]");
 159                 return -1;
 160         }
 161         sel = RTA_DATA(tb[TCA_NAT_PARMS]);
 162
 163         len = ffs(sel->mask);
 164         len = len ? 33 - len : 0;
 165
 166         fprintf(f, " nat %s %s/%d %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
 167                                        "egress" : "ingress",
 168                 format_host_r(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
 169                 len,
 170                 format_host_r(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)));
 171         print_action_control(f, " ", sel->action, "");
 172
 173         if (show_stats) {
 174                 if (tb[TCA_NAT_TM]) {
 175                         struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
 176
 177                         print_tm(f, tm);
 178                 }
 179         }
 180
 181         return 0;
 182 }
 183
 184 struct action_util nat_action_util = {
 185         .id = "nat",
 186         .parse_aopt = parse_nat,
 187         .print_aopt = print_nat,
 188 };