extensions/libipt_pkttype.c

   1 /*
   2  * Shared library add-on to iptables to match
   3  * packets by their type (BROADCAST, UNICAST, MULTICAST).
   4  *
   5  * Michal Ludvig <michal@logix.cz>
   6  */
   7 #include <stdio.h>
   8 #include <netdb.h>
   9 #include <string.h>
  10 #include <stdlib.h>
  11 #include <getopt.h>
  12 #if defined(__GLIBC__) && __GLIBC__ == 2
  13 #include <net/ethernet.h>
  14 #else
  15 #include <linux/if_ether.h>
  16 #endif
  17 #include <iptables.h>
  18 #include <linux/if_packet.h>
  19 #include <linux/netfilter_ipv4/ipt_pkttype.h>
  20
  21 #define PKTTYPE_VERSION "0.1"
  22
  23 struct pkttypes {
  24         const char *name;
  25         unsigned char pkttype;
  26         unsigned char printhelp;
  27         const char *help;
  28 };
  29
  30 static const struct pkttypes supported_types[] = {
  31         {"unicast", PACKET_HOST, 1, "to us"},
  32         {"broadcast", PACKET_BROADCAST, 1, "to all"},
  33         {"multicast", PACKET_MULTICAST, 1, "to group"},
  34 /*
  35         {"otherhost", PACKET_OTHERHOST, 1, "to someone else"},
  36         {"outgoing", PACKET_OUTGOING, 1, "outgoing of any type"},
  37 */
  38         /* aliases */
  39         {"bcast", PACKET_BROADCAST, 0, NULL},
  40         {"mcast", PACKET_MULTICAST, 0, NULL},
  41         {"host", PACKET_HOST, 0, NULL}
  42 };
  43
  44 static void print_types()
  45 {
  46         unsigned int    i;
  47
  48         printf("Valid packet types:\n");
  49         for (i = 0; i < sizeof(supported_types)/sizeof(struct pkttypes); i++)
  50         {
  51                 if(supported_types[i].printhelp == 1)
  52                         printf("\t%-14s\t\t%s\n", supported_types[i].name, supported_types[i].help);
  53         }
  54         printf("\n");
  55 }
  56
  57 /* Function which prints out usage message. */
  58 static void help(void)
  59 {
  60         printf(
  61 "pkt_type v%s options:\n"
  62 "  --pkt-type [!] packettype\tmatch packet type\n"
  63 "\n", PKTTYPE_VERSION);
  64         print_types();
  65 }
  66
  67 static struct option opts[] = {
  68         {"pkt-type", 1, 0, '1'},
  69         {0}
  70 };
  71
  72 static void parse_pkttype(const char *pkttype, struct ipt_pkttype_info *info)
  73 {
  74         unsigned int    i;
  75
  76         for (i = 0; i < sizeof(supported_types)/sizeof(struct pkttypes); i++)
  77         {
  78                 if(strcasecmp(pkttype, supported_types[i].name)==0)
  79                 {
  80                         info->pkttype=supported_types[i].pkttype;
  81                         return;
  82                 }
  83         }
  84
  85         exit_error(PARAMETER_PROBLEM, "Bad packet type '%s'", pkttype);
  86 }
  87
  88 static int parse(int c, char **argv, int invert, unsigned int *flags,
  89       const struct ipt_entry *entry,
  90       unsigned int *nfcache,
  91       struct ipt_entry_match **match)
  92 {
  93         struct ipt_pkttype_info *info = (struct ipt_pkttype_info *)(*match)->data;
  94
  95         switch(c)
  96         {
  97                 case '1':
  98                         check_inverse(optarg, &invert, &optind, 0);
  99                         parse_pkttype(argv[optind-1], info);
 100                         if(invert)
 101                                 info->invert=1;
 102                         *flags=1;
 103                         break;
 104
 105                 default:
 106                         return 0;
 107         }
 108
 109         return 1;
 110 }
 111
 112 static void final_check(unsigned int flags)
 113 {
 114         if (!flags)
 115                 exit_error(PARAMETER_PROBLEM, "You must specify `--pkt-type'");
 116 }
 117
 118 static void print_pkttype(struct ipt_pkttype_info *info)
 119 {
 120         unsigned int    i;
 121
 122         for (i = 0; i < sizeof(supported_types)/sizeof(struct pkttypes); i++)
 123         {
 124                 if(supported_types[i].pkttype==info->pkttype)
 125                 {
 126                         printf("%s ", supported_types[i].name);
 127                         return;
 128                 }
 129         }
 130
 131         printf("%d ", info->pkttype);   /* in case we didn't find an entry in named-packtes */
 132 }
 133
 134 static void print(const struct ipt_ip *ip, const struct ipt_entry_match *match, int numeric)
 135 {
 136         struct ipt_pkttype_info *info = (struct ipt_pkttype_info *)match->data;
 137
 138         printf("PKTTYPE %s= ", info->invert?"!":"");
 139         print_pkttype(info);
 140 }
 141
 142 static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
 143 {
 144         struct ipt_pkttype_info *info = (struct ipt_pkttype_info *)match->data;
 145
 146         printf("--pkt-type %s", info->invert?"! ":"");
 147         print_pkttype(info);
 148 }
 149
 150 static struct iptables_match pkttype = {
 151         .next           = NULL,
 152         .name           = "pkttype",
 153         .version        = IPTABLES_VERSION,
 154         .size           = IPT_ALIGN(sizeof(struct ipt_pkttype_info)),
 155         .userspacesize  = IPT_ALIGN(sizeof(struct ipt_pkttype_info)),
 156         .help           = &help,
 157         .parse          = &parse,
 158         .final_check    = &final_check,
 159         .print          = &print,
 160         .save           = &save,
 161         .extra_opts     = opts
 162 };
 163
 164 void _init(void)
 165 {
 166         register_match(&pkttype);
 167 }