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/module.h>
12 #include <linux/ctype.h>
13 #include <linux/skbuff.h>
16 #include <linux/udp.h>
18 #include <linux/netfilter.h>
19 #include <linux/netfilter_ipv4.h>
20 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
21 #include <linux/netfilter_ipv4/ip_conntrack_sip.h>
26 #define DEBUGP(format, args...)
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
31 MODULE_DESCRIPTION("SIP connection tracking helper");
34 static unsigned short ports[MAX_PORTS];
36 module_param_array(ports, ushort, &ports_c, 0400);
37 MODULE_PARM_DESC(ports, "port numbers of sip servers");
39 static unsigned int sip_timeout = SIP_TIMEOUT;
40 module_param(sip_timeout, uint, 0600);
41 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
43 unsigned int (*ip_nat_sip_hook)(struct sk_buff **pskb,
44 enum ip_conntrack_info ctinfo,
45 struct ip_conntrack *ct,
47 EXPORT_SYMBOL_GPL(ip_nat_sip_hook);
49 unsigned int (*ip_nat_sdp_hook)(struct sk_buff **pskb,
50 enum ip_conntrack_info ctinfo,
51 struct ip_conntrack_expect *exp,
53 EXPORT_SYMBOL_GPL(ip_nat_sdp_hook);
55 int ct_sip_get_info(const char *dptr, size_t dlen,
56 unsigned int *matchoff,
57 unsigned int *matchlen,
58 struct sip_header_nfo *hnfo);
59 EXPORT_SYMBOL_GPL(ct_sip_get_info);
62 static int digits_len(const char *dptr, const char *limit, int *shift);
63 static int epaddr_len(const char *dptr, const char *limit, int *shift);
64 static int skp_digits_len(const char *dptr, const char *limit, int *shift);
65 static int skp_epaddr_len(const char *dptr, const char *limit, int *shift);
67 struct sip_header_nfo ct_sip_hdrs[] = {
70 .lnlen = sizeof("Via:") - 1,
72 .snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
74 .ln_strlen = sizeof("UDP ") - 1,
75 .match_len = epaddr_len,
77 { /* Contact header */
79 .lnlen = sizeof("Contact:") - 1,
81 .snlen = sizeof("\r\nm:") - 1,
83 .ln_strlen = sizeof("sip:") - 1,
84 .match_len = skp_epaddr_len
86 { /* Content length header */
87 .lname = "Content-Length:",
88 .lnlen = sizeof("Content-Length:") - 1,
90 .snlen = sizeof("\r\nl:") - 1,
92 .ln_strlen = sizeof(":") - 1,
93 .match_len = skp_digits_len
95 { /* SDP media info */
97 .lnlen = sizeof("\nm=") - 1,
99 .snlen = sizeof("\rm=") - 1,
101 .ln_strlen = sizeof("audio ") - 1,
102 .match_len = digits_len
104 { /* SDP owner address*/
106 .lnlen = sizeof("\no=") - 1,
108 .snlen = sizeof("\ro=") - 1,
110 .ln_strlen = sizeof("IN IP4 ") - 1,
111 .match_len = epaddr_len
113 { /* SDP connection info */
115 .lnlen = sizeof("\nc=") - 1,
117 .snlen = sizeof("\rc=") - 1,
119 .ln_strlen = sizeof("IN IP4 ") - 1,
120 .match_len = epaddr_len
122 { /* Requests headers */
124 .lnlen = sizeof("sip:") - 1,
126 .snlen = sizeof("sip:") - 1, /* yes, i know.. ;) */
128 .ln_strlen = sizeof("@") - 1,
129 .match_len = epaddr_len
131 { /* SDP version header */
133 .lnlen = sizeof("\nv=") - 1,
135 .snlen = sizeof("\rv=") - 1,
137 .ln_strlen = sizeof("=") - 1,
138 .match_len = digits_len
141 EXPORT_SYMBOL_GPL(ct_sip_hdrs);
143 /* get line lenght until first CR or LF seen. */
144 int ct_sip_lnlen(const char *line, const char *limit)
146 const char *k = line;
148 while ((line <= limit) && (*line == '\r' || *line == '\n'))
151 while (line <= limit) {
152 if (*line == '\r' || *line == '\n')
158 EXPORT_SYMBOL_GPL(ct_sip_lnlen);
160 /* Linear string search, case sensitive. */
161 const char *ct_sip_search(const char *needle, const char *haystack,
162 size_t needle_len, size_t haystack_len)
164 const char *limit = haystack + (haystack_len - needle_len);
166 while (haystack <= limit) {
167 if (memcmp(haystack, needle, needle_len) == 0)
173 EXPORT_SYMBOL_GPL(ct_sip_search);
175 static int digits_len(const char *dptr, const char *limit, int *shift)
178 while (dptr <= limit && isdigit(*dptr)) {
185 /* get digits lenght, skiping blank spaces. */
186 static int skp_digits_len(const char *dptr, const char *limit, int *shift)
188 for (; dptr <= limit && *dptr == ' '; dptr++)
191 return digits_len(dptr, limit, shift);
194 /* Simple ipaddr parser.. */
195 static int parse_ipaddr(const char *cp, const char **endp,
196 u_int32_t *ipaddr, const char *limit)
198 unsigned long int val;
201 for (i = 0, *ipaddr = 0; cp <= limit && i < 4; i++) {
206 val = simple_strtoul(cp, (char **)&cp, 10);
210 ((u_int8_t *)ipaddr)[i] = val;
226 /* skip ip address. returns it lenght. */
227 static int epaddr_len(const char *dptr, const char *limit, int *shift)
229 const char *aux = dptr;
232 if (parse_ipaddr(dptr, &dptr, &ip, limit) < 0) {
233 DEBUGP("ip: %s parse failed.!\n", dptr);
240 dptr += digits_len(dptr, limit, shift);
245 /* get address length, skiping user info. */
246 static int skp_epaddr_len(const char *dptr, const char *limit, int *shift)
250 for (; dptr <= limit && *dptr != '@'; dptr++)
259 return epaddr_len(dptr, limit, shift);
262 /* Returns 0 if not found, -1 error parsing. */
263 int ct_sip_get_info(const char *dptr, size_t dlen,
264 unsigned int *matchoff,
265 unsigned int *matchlen,
266 struct sip_header_nfo *hnfo)
268 const char *limit, *aux, *k = dptr;
271 limit = dptr + (dlen - hnfo->lnlen);
273 while (dptr <= limit) {
274 if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
275 (strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
279 aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
280 ct_sip_lnlen(dptr, limit));
282 DEBUGP("'%s' not found in '%s'.\n", hnfo->ln_str,
286 aux += hnfo->ln_strlen;
288 *matchlen = hnfo->match_len(aux, limit, &shift);
292 *matchoff = (aux - k) + shift;
294 DEBUGP("%s match succeeded! - len: %u\n", hnfo->lname,
298 DEBUGP("%s header not found.\n", hnfo->lname);
302 static int set_expected_rtp(struct sk_buff **pskb,
303 struct ip_conntrack *ct,
304 enum ip_conntrack_info ctinfo,
305 u_int32_t ipaddr, u_int16_t port,
308 struct ip_conntrack_expect *exp;
309 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
312 exp = ip_conntrack_expect_alloc(ct);
316 exp->tuple.src.ip = ct->tuplehash[!dir].tuple.src.ip;
317 exp->tuple.src.u.udp.port = 0;
318 exp->tuple.dst.ip = ipaddr;
319 exp->tuple.dst.u.udp.port = htons(port);
320 exp->tuple.dst.protonum = IPPROTO_UDP;
322 exp->mask.src.ip = 0xFFFFFFFF;
323 exp->mask.src.u.udp.port = 0;
324 exp->mask.dst.ip = 0xFFFFFFFF;
325 exp->mask.dst.u.udp.port = 0xFFFF;
326 exp->mask.dst.protonum = 0xFF;
328 exp->expectfn = NULL;
332 ret = ip_nat_sdp_hook(pskb, ctinfo, exp, dptr);
334 if (ip_conntrack_expect_related(exp) != 0)
339 ip_conntrack_expect_put(exp);
344 static int sip_help(struct sk_buff **pskb,
345 struct ip_conntrack *ct,
346 enum ip_conntrack_info ctinfo)
348 unsigned int dataoff, datalen;
351 int matchoff, matchlen;
356 dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
357 if (dataoff >= (*pskb)->len) {
358 DEBUGP("skb->len = %u\n", (*pskb)->len);
362 ip_ct_refresh(ct, *pskb, sip_timeout * HZ);
364 if (!skb_is_nonlinear(*pskb))
365 dptr = (*pskb)->data + dataoff;
367 DEBUGP("Copy of skbuff not supported yet.\n");
371 if (ip_nat_sip_hook) {
372 if (!ip_nat_sip_hook(pskb, ctinfo, ct, &dptr)) {
378 /* After this point NAT, could have mangled skb, so
379 we need to recalculate payload lenght. */
380 datalen = (*pskb)->len - dataoff;
382 if (datalen < (sizeof("SIP/2.0 200") - 1))
385 /* RTP info only in some SDP pkts */
386 if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
387 memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
390 /* Get ip and port address from SDP packet. */
391 if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
392 &ct_sip_hdrs[POS_CONNECTION]) > 0) {
394 /* We'll drop only if there are parse problems. */
395 if (parse_ipaddr(dptr + matchoff, NULL, &ipaddr,
396 dptr + datalen) < 0) {
400 if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
401 &ct_sip_hdrs[POS_MEDIA]) > 0) {
403 port = simple_strtoul(dptr + matchoff, NULL, 10);
408 ret = set_expected_rtp(pskb, ct, ctinfo,
416 static struct ip_conntrack_helper sip[MAX_PORTS];
417 static char sip_names[MAX_PORTS][10];
419 static void fini(void)
422 for (i = 0; i < ports_c; i++) {
423 DEBUGP("unregistering helper for port %d\n", ports[i]);
424 ip_conntrack_helper_unregister(&sip[i]);
428 static int __init init(void)
434 ports[ports_c++] = SIP_PORT;
436 for (i = 0; i < ports_c; i++) {
437 /* Create helper structure */
438 memset(&sip[i], 0, sizeof(struct ip_conntrack_helper));
440 sip[i].tuple.dst.protonum = IPPROTO_UDP;
441 sip[i].tuple.src.u.udp.port = htons(ports[i]);
442 sip[i].mask.src.u.udp.port = 0xFFFF;
443 sip[i].mask.dst.protonum = 0xFF;
444 sip[i].max_expected = 2;
445 sip[i].timeout = 3 * 60; /* 3 minutes */
446 sip[i].me = THIS_MODULE;
447 sip[i].help = sip_help;
449 tmpname = &sip_names[i][0];
450 if (ports[i] == SIP_PORT)
451 sprintf(tmpname, "sip");
453 sprintf(tmpname, "sip-%d", i);
454 sip[i].name = tmpname;
456 DEBUGP("port #%d: %d\n", i, ports[i]);
458 ret = ip_conntrack_helper_register(&sip[i]);
460 printk("ERROR registering helper for port %d\n",