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
print_types()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. */
help(void)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
parse_pkttype(const char * pkttype,struct ipt_pkttype_info * info)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
parse(int c,char ** argv,int invert,unsigned int * flags,const struct ipt_entry * entry,unsigned int * nfcache,struct ipt_entry_match ** match)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
final_check(unsigned int flags)112 static void final_check(unsigned int flags)
113 {
114 if (!flags)
115 exit_error(PARAMETER_PROBLEM, "You must specify `--pkt-type'");
116 }
117
print_pkttype(struct ipt_pkttype_info * info)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
print(const struct ipt_ip * ip,const struct ipt_entry_match * match,int numeric)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
save(const struct ipt_ip * ip,const struct ipt_entry_match * match)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
ipt_pkttype_init(void)164 void ipt_pkttype_init(void)
165 {
166 register_match(&pkttype);
167 }
168