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 "utils.h"
  23 #include "tc_util.h"
  24 #include <linux/tc_act/tc_nat.h>
  25
  26 static void
  27 explain(void)
  28 {
  29         fprintf(stderr, "Usage: ... nat NAT\n"
  30                         "NAT := DIRECTION OLD NEW\n"
  31                         "DIRECTION := { ingress | egress }\n"
  32                         "OLD := PREFIX\n"
  33                         "NEW := ADDRESS\n");
  34 }
  35
  36 static void
  37 usage(void)
  38 {
  39         explain();
  40         exit(-1);
  41 }
  42
  43 static int
  44 parse_nat_args(int *argc_p, char ***argv_p, struct tc_nat *sel)
  45 {
  46         int argc = *argc_p;
  47         char **argv = *argv_p;
  48         inet_prefix addr;
  49
  50         if (argc <= 0)
  51                 return -1;
  52
  53         if (matches(*argv, "egress") == 0)
  54                 sel->flags |= TCA_NAT_FLAG_EGRESS;
  55         else if (matches(*argv, "ingress") != 0)
  56                 goto bad_val;
  57
  58         NEXT_ARG();
  59
  60         if (get_prefix_1(&addr, *argv, AF_INET))
  61                 goto bad_val;
  62
  63         sel->old_addr = addr.data[0];
  64         sel->mask = htonl(~0u << (32 - addr.bitlen));
  65
  66         NEXT_ARG();
  67
  68         if (get_prefix_1(&addr, *argv, AF_INET))
  69                 goto bad_val;
  70
  71         sel->new_addr = addr.data[0];
  72
  73         argc--;
  74         argv++;
  75
  76         *argc_p = argc;
  77         *argv_p = argv;
  78         return 0;
  79
  80 bad_val:
  81         return -1;
  82 }
  83
  84 static int
  85 parse_nat(struct action_util *a, int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
  86 {
  87         struct tc_nat sel = {};
  88
  89         int argc = *argc_p;
  90         char **argv = *argv_p;
  91         int ok = 0;
  92         struct rtattr *tail;
  93
  94         while (argc > 0) {
  95                 if (matches(*argv, "nat") == 0) {
  96                         NEXT_ARG();
  97                         if (parse_nat_args(&argc, &argv, &sel)) {
  98                                 fprintf(stderr, "Illegal nat construct (%s)\n",
  99                                         *argv);
 100                                 explain();
 101                                 return -1;
 102                         }
 103                         ok++;
 104                         continue;
 105                 } else if (matches(*argv, "help") == 0) {
 106                         usage();
 107                 } else {
 108                         break;
 109                 }
 110
 111         }
 112
 113         if (!ok) {
 114                 explain();
 115                 return -1;
 116         }
 117
 118         if (argc && !action_a2n(*argv, &sel.action, false))
 119                 NEXT_ARG_FWD();
 120
 121         if (argc) {
 122                 if (matches(*argv, "index") == 0) {
 123                         NEXT_ARG();
 124                         if (get_u32(&sel.index, *argv, 10)) {
 125                                 fprintf(stderr, "Nat: Illegal \"index\"\n");
 126                                 return -1;
 127                         }
 128                         argc--;
 129                         argv++;
 130                 }
 131         }
 132
 133         tail = NLMSG_TAIL(n);
 134         addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 135         addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
 136         tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
 137
 138         *argc_p = argc;
 139         *argv_p = argv;
 140         return 0;
 141 }
 142
 143 static int
 144 print_nat(struct action_util *au, FILE * f, struct rtattr *arg)
 145 {
 146         struct tc_nat *sel;
 147         struct rtattr *tb[TCA_NAT_MAX + 1];
 148         char buf1[256];
 149         char buf2[256];
 150
 151         int len;
 152
 153         if (arg == NULL)
 154                 return -1;
 155
 156         parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
 157
 158         if (tb[TCA_NAT_PARMS] == NULL) {
 159                 fprintf(f, "[NULL nat parameters]");
 160                 return -1;
 161         }
 162         sel = RTA_DATA(tb[TCA_NAT_PARMS]);
 163
 164         len = ffs(sel->mask);
 165         len = len ? 33 - len : 0;
 166
 167         fprintf(f, " nat %s %s/%d %s %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
 168                                           "egress" : "ingress",
 169                 format_host_r(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
 170                 len,
 171                 format_host_r(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)),
 172                 action_n2a(sel->action));
 173
 174         if (show_stats) {
 175                 if (tb[TCA_NAT_TM]) {
 176                         struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
 177
 178                         print_tm(f, tm);
 179                 }
 180         }
 181
 182         return 0;
 183 }
 184
 185 struct action_util nat_action_util = {
 186         .id = "nat",
 187         .parse_aopt = parse_nat,
 188         .print_aopt = print_nat,
 189 };