1 /* Shared library add-on to iptables to add UDP support. */
2 #include <stdio.h>
3 #include <netdb.h>
4 #include <string.h>
5 #include <stdlib.h>
6 #include <getopt.h>
7 #include <iptables.h>
8 #include <linux/netfilter_ipv4/ip_tables.h>
9 #include <netinet/in.h>
10
11 /* Function which prints out usage message. */
12 static void
help(void)13 help(void)
14 {
15 printf(
16 "UDP v%s options:\n"
17 " --source-port [!] port[:port]\n"
18 " --sport ...\n"
19 " match source port(s)\n"
20 " --destination-port [!] port[:port]\n"
21 " --dport ...\n"
22 " match destination port(s)\n",
23 IPTABLES_VERSION);
24 }
25
26 static struct option opts[] = {
27 { "source-port", 1, 0, '1' },
28 { "sport", 1, 0, '1' }, /* synonym */
29 { "destination-port", 1, 0, '2' },
30 { "dport", 1, 0, '2' }, /* synonym */
31 {0}
32 };
33
34 static void
parse_udp_ports(const char * portstring,u_int16_t * ports)35 parse_udp_ports(const char *portstring, u_int16_t *ports)
36 {
37 char *buffer;
38 char *cp;
39
40 buffer = strdup(portstring);
41 if ((cp = strchr(buffer, ':')) == NULL)
42 ports[0] = ports[1] = parse_port(buffer, "udp");
43 else {
44 *cp = '\0';
45 cp++;
46
47 ports[0] = buffer[0] ? parse_port(buffer, "udp") : 0;
48 ports[1] = cp[0] ? parse_port(cp, "udp") : 0xFFFF;
49
50 if (ports[0] > ports[1])
51 exit_error(PARAMETER_PROBLEM,
52 "invalid portrange (min > max)");
53 }
54 free(buffer);
55 }
56
57 /* Initialize the match. */
58 static void
init(struct ipt_entry_match * m,unsigned int * nfcache)59 init(struct ipt_entry_match *m, unsigned int *nfcache)
60 {
61 struct ipt_udp *udpinfo = (struct ipt_udp *)m->data;
62
63 udpinfo->spts[1] = udpinfo->dpts[1] = 0xFFFF;
64 }
65
66 #define UDP_SRC_PORTS 0x01
67 #define UDP_DST_PORTS 0x02
68
69 /* Function which parses command options; returns true if it
70 ate an option */
71 static int
parse(int c,char ** argv,int invert,unsigned int * flags,const struct ipt_entry * entry,unsigned int * nfcache,struct ipt_entry_match ** match)72 parse(int c, char **argv, int invert, unsigned int *flags,
73 const struct ipt_entry *entry,
74 unsigned int *nfcache,
75 struct ipt_entry_match **match)
76 {
77 struct ipt_udp *udpinfo = (struct ipt_udp *)(*match)->data;
78
79 switch (c) {
80 case '1':
81 if (*flags & UDP_SRC_PORTS)
82 exit_error(PARAMETER_PROBLEM,
83 "Only one `--source-port' allowed");
84 check_inverse(optarg, &invert, &optind, 0);
85 parse_udp_ports(argv[optind-1], udpinfo->spts);
86 if (invert)
87 udpinfo->invflags |= IPT_UDP_INV_SRCPT;
88 *flags |= UDP_SRC_PORTS;
89 break;
90
91 case '2':
92 if (*flags & UDP_DST_PORTS)
93 exit_error(PARAMETER_PROBLEM,
94 "Only one `--destination-port' allowed");
95 check_inverse(optarg, &invert, &optind, 0);
96 parse_udp_ports(argv[optind-1], udpinfo->dpts);
97 if (invert)
98 udpinfo->invflags |= IPT_UDP_INV_DSTPT;
99 *flags |= UDP_DST_PORTS;
100 break;
101
102 default:
103 return 0;
104 }
105
106 return 1;
107 }
108
109 /* Final check; we don't care. */
110 static void
final_check(unsigned int flags)111 final_check(unsigned int flags)
112 {
113 }
114
115 static char *
port_to_service(int port)116 port_to_service(int port)
117 {
118 struct servent *service;
119
120 if ((service = getservbyport(htons(port), "udp")))
121 return service->s_name;
122
123 return NULL;
124 }
125
126 static void
print_port(u_int16_t port,int numeric)127 print_port(u_int16_t port, int numeric)
128 {
129 char *service;
130
131 if (numeric || (service = port_to_service(port)) == NULL)
132 printf("%u", port);
133 else
134 printf("%s", service);
135 }
136
137 static void
print_ports(const char * name,u_int16_t min,u_int16_t max,int invert,int numeric)138 print_ports(const char *name, u_int16_t min, u_int16_t max,
139 int invert, int numeric)
140 {
141 const char *inv = invert ? "!" : "";
142
143 if (min != 0 || max != 0xFFFF || invert) {
144 printf("%s", name);
145 if (min == max) {
146 printf(":%s", inv);
147 print_port(min, numeric);
148 } else {
149 printf("s:%s", inv);
150 print_port(min, numeric);
151 printf(":");
152 print_port(max, numeric);
153 }
154 printf(" ");
155 }
156 }
157
158 /* Prints out the union ipt_matchinfo. */
159 static void
print(const struct ipt_ip * ip,const struct ipt_entry_match * match,int numeric)160 print(const struct ipt_ip *ip,
161 const struct ipt_entry_match *match, int numeric)
162 {
163 const struct ipt_udp *udp = (struct ipt_udp *)match->data;
164
165 printf("udp ");
166 print_ports("spt", udp->spts[0], udp->spts[1],
167 udp->invflags & IPT_UDP_INV_SRCPT,
168 numeric);
169 print_ports("dpt", udp->dpts[0], udp->dpts[1],
170 udp->invflags & IPT_UDP_INV_DSTPT,
171 numeric);
172 if (udp->invflags & ~IPT_UDP_INV_MASK)
173 printf("Unknown invflags: 0x%X ",
174 udp->invflags & ~IPT_UDP_INV_MASK);
175 }
176
177 /* Saves the union ipt_matchinfo in parsable form to stdout. */
save(const struct ipt_ip * ip,const struct ipt_entry_match * match)178 static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
179 {
180 const struct ipt_udp *udpinfo = (struct ipt_udp *)match->data;
181
182 if (udpinfo->spts[0] != 0
183 || udpinfo->spts[1] != 0xFFFF) {
184 if (udpinfo->invflags & IPT_UDP_INV_SRCPT)
185 printf("! ");
186 if (udpinfo->spts[0]
187 != udpinfo->spts[1])
188 printf("--sport %u:%u ",
189 udpinfo->spts[0],
190 udpinfo->spts[1]);
191 else
192 printf("--sport %u ",
193 udpinfo->spts[0]);
194 }
195
196 if (udpinfo->dpts[0] != 0
197 || udpinfo->dpts[1] != 0xFFFF) {
198 if (udpinfo->invflags & IPT_UDP_INV_DSTPT)
199 printf("! ");
200 if (udpinfo->dpts[0]
201 != udpinfo->dpts[1])
202 printf("--dport %u:%u ",
203 udpinfo->dpts[0],
204 udpinfo->dpts[1]);
205 else
206 printf("--dport %u ",
207 udpinfo->dpts[0]);
208 }
209 }
210
211 static
212 struct iptables_match udp = {
213 .next = NULL,
214 .name = "udp",
215 .version = IPTABLES_VERSION,
216 .size = IPT_ALIGN(sizeof(struct ipt_udp)),
217 .userspacesize = IPT_ALIGN(sizeof(struct ipt_udp)),
218 .help = &help,
219 .init = &init,
220 .parse = &parse,
221 .final_check = &final_check,
222 .print = &print,
223 .save = &save,
224 .extra_opts = opts
225 };
226
227 void
ipt_udp_init(void)228 ipt_udp_init(void)
229 {
230 register_match(&udp);
231 }
232