1 /* SIP extension for IP connection tracking.
3 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
4 * based on RR's ip_conntrack_ftp.c and other modules.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/config.h>
12 #include <linux/module.h>
13 #include <linux/ctype.h>
14 #include <linux/skbuff.h>
17 #include <linux/udp.h>
19 #include <linux/netfilter.h>
20 #include <linux/netfilter_ipv4.h>
21 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
22 #include <linux/netfilter_ipv4/ip_conntrack_sip.h>
27 #define DEBUGP(format, args...)
30 MODULE_LICENSE("GPL");
31 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
32 MODULE_DESCRIPTION("SIP connection tracking helper");
35 static unsigned short ports
[MAX_PORTS
];
37 module_param_array(ports
, ushort
, &ports_c
, 0400);
38 MODULE_PARM_DESC(ports
, "port numbers of sip servers");
40 static unsigned int sip_timeout
= SIP_TIMEOUT
;
41 module_param(sip_timeout
, uint
, 0600);
42 MODULE_PARM_DESC(sip_timeout
, "timeout for the master SIP session");
44 unsigned int (*ip_nat_sip_hook
)(struct sk_buff
**pskb
,
45 enum ip_conntrack_info ctinfo
,
46 struct ip_conntrack
*ct
,
48 EXPORT_SYMBOL_GPL(ip_nat_sip_hook
);
50 unsigned int (*ip_nat_sdp_hook
)(struct sk_buff
**pskb
,
51 enum ip_conntrack_info ctinfo
,
52 struct ip_conntrack_expect
*exp
,
54 EXPORT_SYMBOL_GPL(ip_nat_sdp_hook
);
56 int ct_sip_get_info(const char *dptr
, size_t dlen
,
57 unsigned int *matchoff
,
58 unsigned int *matchlen
,
59 struct sip_header_nfo
*hnfo
);
60 EXPORT_SYMBOL_GPL(ct_sip_get_info
);
63 static int digits_len(const char *dptr
, const char *limit
, int *shift
);
64 static int epaddr_len(const char *dptr
, const char *limit
, int *shift
);
65 static int skp_digits_len(const char *dptr
, const char *limit
, int *shift
);
66 static int skp_epaddr_len(const char *dptr
, const char *limit
, int *shift
);
68 struct sip_header_nfo ct_sip_hdrs
[] = {
71 .lnlen
= sizeof("Via:") - 1,
73 .snlen
= sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
75 .ln_strlen
= sizeof("UDP ") - 1,
76 .match_len
= epaddr_len
,
78 { /* Contact header */
80 .lnlen
= sizeof("Contact:") - 1,
82 .snlen
= sizeof("\r\nm:") - 1,
84 .ln_strlen
= sizeof("sip:") - 1,
85 .match_len
= skp_epaddr_len
87 { /* Content length header */
88 .lname
= "Content-Length:",
89 .lnlen
= sizeof("Content-Length:") - 1,
91 .snlen
= sizeof("\r\nl:") - 1,
93 .ln_strlen
= sizeof(":") - 1,
94 .match_len
= skp_digits_len
96 { /* SDP media info */
98 .lnlen
= sizeof("\nm=") - 1,
100 .snlen
= sizeof("\rm=") - 1,
102 .ln_strlen
= sizeof("audio ") - 1,
103 .match_len
= digits_len
105 { /* SDP owner address*/
107 .lnlen
= sizeof("\no=") - 1,
109 .snlen
= sizeof("\ro=") - 1,
111 .ln_strlen
= sizeof("IN IP4 ") - 1,
112 .match_len
= epaddr_len
114 { /* SDP connection info */
116 .lnlen
= sizeof("\nc=") - 1,
118 .snlen
= sizeof("\rc=") - 1,
120 .ln_strlen
= sizeof("IN IP4 ") - 1,
121 .match_len
= epaddr_len
123 { /* Requests headers */
125 .lnlen
= sizeof("sip:") - 1,
127 .snlen
= sizeof("sip:") - 1, /* yes, i know.. ;) */
129 .ln_strlen
= sizeof("@") - 1,
130 .match_len
= epaddr_len
132 { /* SDP version header */
134 .lnlen
= sizeof("\nv=") - 1,
136 .snlen
= sizeof("\rv=") - 1,
138 .ln_strlen
= sizeof("=") - 1,
139 .match_len
= digits_len
142 EXPORT_SYMBOL_GPL(ct_sip_hdrs
);
144 /* get line lenght until first CR or LF seen. */
145 int ct_sip_lnlen(const char *line
, const char *limit
)
147 const char *k
= line
;
149 while ((line
<= limit
) && (*line
== '\r' || *line
== '\n'))
152 while (line
<= limit
) {
153 if (*line
== '\r' || *line
== '\n')
159 EXPORT_SYMBOL_GPL(ct_sip_lnlen
);
161 /* Linear string search, case sensitive. */
162 const char *ct_sip_search(const char *needle
, const char *haystack
,
163 size_t needle_len
, size_t haystack_len
)
165 const char *limit
= haystack
+ (haystack_len
- needle_len
);
167 while (haystack
<= limit
) {
168 if (memcmp(haystack
, needle
, needle_len
) == 0)
174 EXPORT_SYMBOL_GPL(ct_sip_search
);
176 static int digits_len(const char *dptr
, const char *limit
, int *shift
)
179 while (dptr
<= limit
&& isdigit(*dptr
)) {
186 /* get digits lenght, skiping blank spaces. */
187 static int skp_digits_len(const char *dptr
, const char *limit
, int *shift
)
189 for (; dptr
<= limit
&& *dptr
== ' '; dptr
++)
192 return digits_len(dptr
, limit
, shift
);
195 /* Simple ipaddr parser.. */
196 static int parse_ipaddr(const char *cp
, const char **endp
,
197 u_int32_t
*ipaddr
, const char *limit
)
199 unsigned long int val
;
202 for (i
= 0, *ipaddr
= 0; cp
<= limit
&& i
< 4; i
++) {
207 val
= simple_strtoul(cp
, (char **)&cp
, 10);
211 ((u_int8_t
*)ipaddr
)[i
] = val
;
227 /* skip ip address. returns it lenght. */
228 static int epaddr_len(const char *dptr
, const char *limit
, int *shift
)
230 const char *aux
= dptr
;
233 if (parse_ipaddr(dptr
, &dptr
, &ip
, limit
) < 0) {
234 DEBUGP("ip: %s parse failed.!\n", dptr
);
241 dptr
+= digits_len(dptr
, limit
, shift
);
246 /* get address length, skiping user info. */
247 static int skp_epaddr_len(const char *dptr
, const char *limit
, int *shift
)
251 for (; dptr
<= limit
&& *dptr
!= '@'; dptr
++)
260 return epaddr_len(dptr
, limit
, shift
);
263 /* Returns 0 if not found, -1 error parsing. */
264 int ct_sip_get_info(const char *dptr
, size_t dlen
,
265 unsigned int *matchoff
,
266 unsigned int *matchlen
,
267 struct sip_header_nfo
*hnfo
)
269 const char *limit
, *aux
, *k
= dptr
;
272 limit
= dptr
+ (dlen
- hnfo
->lnlen
);
274 while (dptr
<= limit
) {
275 if ((strncmp(dptr
, hnfo
->lname
, hnfo
->lnlen
) != 0) &&
276 (strncmp(dptr
, hnfo
->sname
, hnfo
->snlen
) != 0)) {
280 aux
= ct_sip_search(hnfo
->ln_str
, dptr
, hnfo
->ln_strlen
,
281 ct_sip_lnlen(dptr
, limit
));
283 DEBUGP("'%s' not found in '%s'.\n", hnfo
->ln_str
,
287 aux
+= hnfo
->ln_strlen
;
289 *matchlen
= hnfo
->match_len(aux
, limit
, &shift
);
293 *matchoff
= (aux
- k
) + shift
;
295 DEBUGP("%s match succeeded! - len: %u\n", hnfo
->lname
,
299 DEBUGP("%s header not found.\n", hnfo
->lname
);
303 static int set_expected_rtp(struct sk_buff
**pskb
,
304 struct ip_conntrack
*ct
,
305 enum ip_conntrack_info ctinfo
,
306 u_int32_t ipaddr
, u_int16_t port
,
309 struct ip_conntrack_expect
*exp
;
310 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
313 exp
= ip_conntrack_expect_alloc(ct
);
317 exp
->tuple
.src
.ip
= ct
->tuplehash
[!dir
].tuple
.src
.ip
;
318 exp
->tuple
.src
.u
.udp
.port
= 0;
319 exp
->tuple
.dst
.ip
= ipaddr
;
320 exp
->tuple
.dst
.u
.udp
.port
= htons(port
);
321 exp
->tuple
.dst
.protonum
= IPPROTO_UDP
;
323 exp
->mask
.src
.ip
= 0xFFFFFFFF;
324 exp
->mask
.src
.u
.udp
.port
= 0;
325 exp
->mask
.dst
.ip
= 0xFFFFFFFF;
326 exp
->mask
.dst
.u
.udp
.port
= 0xFFFF;
327 exp
->mask
.dst
.protonum
= 0xFF;
329 exp
->expectfn
= NULL
;
333 ret
= ip_nat_sdp_hook(pskb
, ctinfo
, exp
, dptr
);
335 if (ip_conntrack_expect_related(exp
) != 0)
340 ip_conntrack_expect_put(exp
);
345 static int sip_help(struct sk_buff
**pskb
,
346 struct ip_conntrack
*ct
,
347 enum ip_conntrack_info ctinfo
)
349 unsigned int dataoff
, datalen
;
352 int matchoff
, matchlen
;
357 dataoff
= (*pskb
)->nh
.iph
->ihl
*4 + sizeof(struct udphdr
);
358 if (dataoff
>= (*pskb
)->len
) {
359 DEBUGP("skb->len = %u\n", (*pskb
)->len
);
363 ip_ct_refresh(ct
, *pskb
, sip_timeout
* HZ
);
365 if (!skb_is_nonlinear(*pskb
))
366 dptr
= (*pskb
)->data
+ dataoff
;
368 DEBUGP("Copy of skbuff not supported yet.\n");
372 if (ip_nat_sip_hook
) {
373 if (!ip_nat_sip_hook(pskb
, ctinfo
, ct
, &dptr
)) {
379 /* After this point NAT, could have mangled skb, so
380 we need to recalculate payload lenght. */
381 datalen
= (*pskb
)->len
- dataoff
;
383 if (datalen
< (sizeof("SIP/2.0 200") - 1))
386 /* RTP info only in some SDP pkts */
387 if (memcmp(dptr
, "INVITE", sizeof("INVITE") - 1) != 0 &&
388 memcmp(dptr
, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
391 /* Get ip and port address from SDP packet. */
392 if (ct_sip_get_info(dptr
, datalen
, &matchoff
, &matchlen
,
393 &ct_sip_hdrs
[POS_CONNECTION
]) > 0) {
395 /* We'll drop only if there are parse problems. */
396 if (parse_ipaddr(dptr
+ matchoff
, NULL
, &ipaddr
,
397 dptr
+ datalen
) < 0) {
401 if (ct_sip_get_info(dptr
, datalen
, &matchoff
, &matchlen
,
402 &ct_sip_hdrs
[POS_MEDIA
]) > 0) {
404 port
= simple_strtoul(dptr
+ matchoff
, NULL
, 10);
409 ret
= set_expected_rtp(pskb
, ct
, ctinfo
,
417 static struct ip_conntrack_helper sip
[MAX_PORTS
];
418 static char sip_names
[MAX_PORTS
][10];
420 static void fini(void)
423 for (i
= 0; i
< ports_c
; i
++) {
424 DEBUGP("unregistering helper for port %d\n", ports
[i
]);
425 ip_conntrack_helper_unregister(&sip
[i
]);
429 static int __init
init(void)
435 ports
[ports_c
++] = SIP_PORT
;
437 for (i
= 0; i
< ports_c
; i
++) {
438 /* Create helper structure */
439 memset(&sip
[i
], 0, sizeof(struct ip_conntrack_helper
));
441 sip
[i
].tuple
.dst
.protonum
= IPPROTO_UDP
;
442 sip
[i
].tuple
.src
.u
.udp
.port
= htons(ports
[i
]);
443 sip
[i
].mask
.src
.u
.udp
.port
= 0xFFFF;
444 sip
[i
].mask
.dst
.protonum
= 0xFF;
445 sip
[i
].max_expected
= 1;
446 sip
[i
].timeout
= 3 * 60; /* 3 minutes */
447 sip
[i
].me
= THIS_MODULE
;
448 sip
[i
].help
= sip_help
;
450 tmpname
= &sip_names
[i
][0];
451 if (ports
[i
] == SIP_PORT
)
452 sprintf(tmpname
, "sip");
454 sprintf(tmpname
, "sip-%d", i
);
455 sip
[i
].name
= tmpname
;
457 DEBUGP("port #%d: %d\n", i
, ports
[i
]);
459 ret
= ip_conntrack_helper_register(&sip
[i
]);
461 printk("ERROR registering helper for port %d\n",