1#include <stdint.h>
2#include <stdio.h>
3#include <netdb.h>
4#include <arpa/inet.h>
5#include <xtables.h>
6#include <linux/netfilter/xt_tcpudp.h>
7
8enum {
9	O_SOURCE_PORT = 0,
10	O_DEST_PORT,
11};
12
13static void udp_help(void)
14{
15	printf(
16"udp match 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}
24
25#define s struct xt_udp
26static const struct xt_option_entry udp_opts[] = {
27	{.name = "source-port", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
28	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
29	{.name = "sport", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
30	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
31	{.name = "destination-port", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
32	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
33	{.name = "dport", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
34	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
35	XTOPT_TABLEEND,
36};
37#undef s
38
39static void udp_init(struct xt_entry_match *m)
40{
41	struct xt_udp *udpinfo = (struct xt_udp *)m->data;
42
43	udpinfo->spts[1] = udpinfo->dpts[1] = 0xFFFF;
44}
45
46static void udp_parse(struct xt_option_call *cb)
47{
48	struct xt_udp *udpinfo = cb->data;
49
50	xtables_option_parse(cb);
51	switch (cb->entry->id) {
52	case O_SOURCE_PORT:
53		if (cb->invert)
54			udpinfo->invflags |= XT_UDP_INV_SRCPT;
55		break;
56	case O_DEST_PORT:
57		if (cb->invert)
58			udpinfo->invflags |= XT_UDP_INV_DSTPT;
59		break;
60	}
61}
62
63static const char *
64port_to_service(int port)
65{
66	const struct servent *service;
67
68	if ((service = getservbyport(htons(port), "udp")))
69		return service->s_name;
70
71	return NULL;
72}
73
74static void
75print_port(uint16_t port, int numeric)
76{
77	const char *service;
78
79	if (numeric || (service = port_to_service(port)) == NULL)
80		printf("%u", port);
81	else
82		printf("%s", service);
83}
84
85static void
86print_ports(const char *name, uint16_t min, uint16_t max,
87	    int invert, int numeric)
88{
89	const char *inv = invert ? "!" : "";
90
91	if (min != 0 || max != 0xFFFF || invert) {
92		printf(" %s", name);
93		if (min == max) {
94			printf(":%s", inv);
95			print_port(min, numeric);
96		} else {
97			printf("s:%s", inv);
98			print_port(min, numeric);
99			printf(":");
100			print_port(max, numeric);
101		}
102	}
103}
104
105static void
106udp_print(const void *ip, const struct xt_entry_match *match, int numeric)
107{
108	const struct xt_udp *udp = (struct xt_udp *)match->data;
109
110	printf(" udp");
111	print_ports("spt", udp->spts[0], udp->spts[1],
112		    udp->invflags & XT_UDP_INV_SRCPT,
113		    numeric);
114	print_ports("dpt", udp->dpts[0], udp->dpts[1],
115		    udp->invflags & XT_UDP_INV_DSTPT,
116		    numeric);
117	if (udp->invflags & ~XT_UDP_INV_MASK)
118		printf(" Unknown invflags: 0x%X",
119		       udp->invflags & ~XT_UDP_INV_MASK);
120}
121
122static void udp_save(const void *ip, const struct xt_entry_match *match)
123{
124	const struct xt_udp *udpinfo = (struct xt_udp *)match->data;
125
126	if (udpinfo->spts[0] != 0
127	    || udpinfo->spts[1] != 0xFFFF) {
128		if (udpinfo->invflags & XT_UDP_INV_SRCPT)
129			printf(" !");
130		if (udpinfo->spts[0]
131		    != udpinfo->spts[1])
132			printf(" --sport %u:%u",
133			       udpinfo->spts[0],
134			       udpinfo->spts[1]);
135		else
136			printf(" --sport %u",
137			       udpinfo->spts[0]);
138	}
139
140	if (udpinfo->dpts[0] != 0
141	    || udpinfo->dpts[1] != 0xFFFF) {
142		if (udpinfo->invflags & XT_UDP_INV_DSTPT)
143			printf(" !");
144		if (udpinfo->dpts[0]
145		    != udpinfo->dpts[1])
146			printf(" --dport %u:%u",
147			       udpinfo->dpts[0],
148			       udpinfo->dpts[1]);
149		else
150			printf(" --dport %u",
151			       udpinfo->dpts[0]);
152	}
153}
154
155static struct xtables_match udp_match = {
156	.family		= NFPROTO_UNSPEC,
157	.name		= "udp",
158	.version	= XTABLES_VERSION,
159	.size		= XT_ALIGN(sizeof(struct xt_udp)),
160	.userspacesize	= XT_ALIGN(sizeof(struct xt_udp)),
161	.help		= udp_help,
162	.init		= udp_init,
163	.print		= udp_print,
164	.save		= udp_save,
165	.x6_parse	= udp_parse,
166	.x6_options	= udp_opts,
167};
168
169void
170_init(void)
171{
172	xtables_register_match(&udp_match);
173}
174