release/src/router/iptables/extensions/libipt_helper.c

   1 /* Shared library add-on to iptables to add related packet matching support. */
   2 #include <stdio.h>
   3 #include <netdb.h>
   4 #include <string.h>
   5 #include <stdlib.h>
   6 #include <getopt.h>
   7
   8 #include <iptables.h>
   9 #include <linux/netfilter_ipv4/ipt_helper.h>
  10
  11 /* Function which prints out usage message. */
  12 static void
  13 help(void)
  14 {
  15         printf(
  16 "helper match v%s options:\n"
  17 "[!] --helper string        Match helper identified by string\n"
  18 "\n",
  19 IPTABLES_VERSION);
  20 }
  21
  22 static struct option opts[] = {
  23         { "helper", 1, 0, '1' },
  24         {0}
  25 };
  26
  27 /* Function which parses command options; returns true if it
  28    ate an option */
  29 static int
  30 parse(int c, char **argv, int invert, unsigned int *flags,
  31       const struct ipt_entry *entry,
  32       unsigned int *nfcache,
  33       struct ipt_entry_match **match)
  34 {
  35         struct ipt_helper_info *info = (struct ipt_helper_info *)(*match)->data;
  36
  37         switch (c) {
  38         case '1':
  39                 if (*flags)
  40                         exit_error(PARAMETER_PROBLEM,
  41                                         "helper match: Only use --helper ONCE!");
  42                 check_inverse(optarg, &invert, &invert, 0);
  43                 strncpy(info->name, optarg, 29);
  44                 info->name[29] = '\0';
  45                 if (invert)
  46                         info->invert = 1;
  47                 *flags = 1;
  48                 break;
  49
  50         default:
  51                 return 0;
  52         }
  53         return 1;
  54 }
  55
  56 /* Final check; must have specified --helper. */
  57 static void
  58 final_check(unsigned int flags)
  59 {
  60         if (!flags)
  61                 exit_error(PARAMETER_PROBLEM,
  62                            "helper match: You must specify `--helper'");
  63 }
  64
  65 /* Prints out the info. */
  66 static void
  67 print(const struct ipt_ip *ip,
  68       const struct ipt_entry_match *match,
  69       int numeric)
  70 {
  71         struct ipt_helper_info *info = (struct ipt_helper_info *)match->data;
  72
  73         printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
  74 }
  75
  76 /* Saves the union ipt_info in parsable form to stdout. */
  77 static void
  78 save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
  79 {
  80         struct ipt_helper_info *info = (struct ipt_helper_info *)match->data;
  81
  82         printf("%s--helper \"%s\" ",info->invert ? "! " : "", info->name);
  83 }
  84
  85 static struct iptables_match helper = {
  86         .next           = NULL,
  87         .name           = "helper",
  88         .version        = IPTABLES_VERSION,
  89         .size           = IPT_ALIGN(sizeof(struct ipt_helper_info)),
  90         .help           = &help,
  91         .parse          = &parse,
  92         .final_check    = &final_check,
  93         .print          = &print,
  94         .save           = &save,
  95         .extra_opts     = opts
  96 };
  97
  98 void _init(void)
  99 {
 100         register_match(&helper);
 101 }