1/*	$NetBSD: ip_raudio_pxy.c,v 1.2 2012/03/23 20:39:50 christos Exp $	*/
2
3/*
4 * Copyright (C) 2012 by Darren Reed.
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * Id: ip_raudio_pxy.c,v 1.1.1.2 2012/07/22 13:45:33 darrenr Exp
9 */
10
11#include <sys/cdefs.h>
12__KERNEL_RCSID(1, "$NetBSD: ip_raudio_pxy.c,v 1.2 2012/03/23 20:39:50 christos Exp $");
13
14#define	IPF_RAUDIO_PROXY
15
16
17void ipf_p_raudio_main_load(void);
18void ipf_p_raudio_main_unload(void);
19int ipf_p_raudio_new(void *, fr_info_t *, ap_session_t *, nat_t *);
20int ipf_p_raudio_in(void *, fr_info_t *, ap_session_t *, nat_t *);
21int ipf_p_raudio_out(void *, fr_info_t *, ap_session_t *, nat_t *);
22
23static	frentry_t	raudiofr;
24
25int	raudio_proxy_init = 0;
26
27
28/*
29 * Real Audio application proxy initialization.
30 */
31void
32ipf_p_raudio_main_load(void)
33{
34	bzero((char *)&raudiofr, sizeof(raudiofr));
35	raudiofr.fr_ref = 1;
36	raudiofr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
37	MUTEX_INIT(&raudiofr.fr_lock, "Real Audio proxy rule lock");
38	raudio_proxy_init = 1;
39}
40
41
42void
43ipf_p_raudio_main_unload(void)
44{
45	if (raudio_proxy_init == 1) {
46		MUTEX_DESTROY(&raudiofr.fr_lock);
47		raudio_proxy_init = 0;
48	}
49}
50
51
52/*
53 * Setup for a new proxy to handle Real Audio.
54 */
55int
56ipf_p_raudio_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
57{
58	raudio_t *rap;
59
60	nat = nat;	/* LINT */
61
62	if (fin->fin_v != 4)
63		return -1;
64
65	KMALLOCS(aps->aps_data, void *, sizeof(raudio_t));
66	if (aps->aps_data == NULL)
67		return -1;
68
69	bzero(aps->aps_data, sizeof(raudio_t));
70	rap = aps->aps_data;
71	aps->aps_psiz = sizeof(raudio_t);
72	rap->rap_mode = RAP_M_TCP;	/* default is for TCP */
73	return 0;
74}
75
76
77
78int
79ipf_p_raudio_out(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
80{
81	raudio_t *rap = aps->aps_data;
82	unsigned char membuf[512 + 1], *s;
83	u_short id = 0;
84	tcphdr_t *tcp;
85	int off, dlen;
86	int len = 0;
87	mb_t *m;
88
89	nat = nat;	/* LINT */
90
91	/*
92	 * If we've already processed the start messages, then nothing left
93	 * for the proxy to do.
94	 */
95	if (rap->rap_eos == 1)
96		return 0;
97
98	m = fin->fin_m;
99	tcp = (tcphdr_t *)fin->fin_dp;
100	off = (char *)tcp - (char *)fin->fin_ip;
101	off += (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
102
103#ifdef __sgi
104	dlen = fin->fin_plen - off;
105#else
106	dlen = MSGDSIZE(m) - off;
107#endif
108	if (dlen <= 0)
109		return 0;
110
111	if (dlen > sizeof(membuf))
112		dlen = sizeof(membuf);
113
114	bzero((char *)membuf, sizeof(membuf));
115	COPYDATA(m, off, dlen, (char *)membuf);
116	/*
117	 * In all the startup parsing, ensure that we don't go outside
118	 * the packet buffer boundary.
119	 */
120	/*
121	 * Look for the start of connection "PNA" string if not seen yet.
122	 */
123	if (rap->rap_seenpna == 0) {
124		s = (u_char *)memstr("PNA", (char *)membuf, 3, dlen);
125		if (s == NULL)
126			return 0;
127		s += 3;
128		rap->rap_seenpna = 1;
129	} else
130		s = membuf;
131
132	/*
133	 * Directly after the PNA will be the version number of this
134	 * connection.
135	 */
136	if (rap->rap_seenpna == 1 && rap->rap_seenver == 0) {
137		if ((s + 1) - membuf < dlen) {
138			rap->rap_version = (*s << 8) | *(s + 1);
139			s += 2;
140			rap->rap_seenver = 1;
141		} else
142			return 0;
143	}
144
145	/*
146	 * Now that we've been past the PNA and version number, we're into the
147	 * startup messages block.  This ends when a message with an ID of 0.
148	 */
149	while ((rap->rap_eos == 0) && ((s + 1) - membuf < dlen)) {
150		if (rap->rap_gotid == 0) {
151			id = (*s << 8) | *(s + 1);
152			s += 2;
153			rap->rap_gotid = 1;
154			if (id == RA_ID_END) {
155				rap->rap_eos = 1;
156				break;
157			}
158		} else if (rap->rap_gotlen == 0) {
159			len = (*s << 8) | *(s + 1);
160			s += 2;
161			rap->rap_gotlen = 1;
162		}
163
164		if (rap->rap_gotid == 1 && rap->rap_gotlen == 1) {
165			if (id == RA_ID_UDP) {
166				rap->rap_mode &= ~RAP_M_TCP;
167				rap->rap_mode |= RAP_M_UDP;
168				rap->rap_plport = (*s << 8) | *(s + 1);
169			} else if (id == RA_ID_ROBUST) {
170				rap->rap_mode |= RAP_M_ROBUST;
171				rap->rap_prport = (*s << 8) | *(s + 1);
172			}
173			s += len;
174			rap->rap_gotlen = 0;
175			rap->rap_gotid = 0;
176		}
177	}
178	return 0;
179}
180
181
182int
183ipf_p_raudio_in(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
184{
185	unsigned char membuf[IPF_MAXPORTLEN + 1], *s;
186	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
187	raudio_t *rap = aps->aps_data;
188	ipf_main_softc_t *softc;
189	ipf_nat_softc_t *softn;
190	struct in_addr swa, swb;
191	int off, dlen, slen;
192	int a1, a2, a3, a4;
193	u_short sp, dp;
194	fr_info_t fi;
195	tcp_seq seq;
196	nat_t *nat2;
197	u_char swp;
198	ip_t *ip;
199	mb_t *m;
200
201	softc = fin->fin_main_soft;
202	softn = softc->ipf_nat_soft;
203	/*
204	 * Wait until we've seen the end of the start messages and even then
205	 * only proceed further if we're using UDP.  If they want to use TCP
206	 * then data is sent back on the same channel that is already open.
207	 */
208	if (rap->rap_sdone != 0)
209		return 0;
210
211	m = fin->fin_m;
212	tcp = (tcphdr_t *)fin->fin_dp;
213	off = (char *)tcp - (char *)fin->fin_ip;
214	off += (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
215
216#ifdef __sgi
217	dlen = fin->fin_plen - off;
218#else
219	dlen = MSGDSIZE(m) - off;
220#endif
221	if (dlen <= 0)
222		return 0;
223
224	if (dlen > sizeof(membuf))
225		dlen = sizeof(membuf);
226
227	bzero((char *)membuf, sizeof(membuf));
228	COPYDATA(m, off, dlen, (char *)membuf);
229
230	seq = ntohl(tcp->th_seq);
231	/*
232	 * Check to see if the data in this packet is of interest to us.
233	 * We only care for the first 19 bytes coming back from the server.
234	 */
235	if (rap->rap_sseq == 0) {
236		s = (u_char *)memstr("PNA", (char *)membuf, 3, dlen);
237		if (s == NULL)
238			return 0;
239		a1 = s - membuf;
240		dlen -= a1;
241		a1 = 0;
242		rap->rap_sseq = seq;
243		a2 = MIN(dlen, sizeof(rap->rap_svr));
244	} else if (seq <= rap->rap_sseq + sizeof(rap->rap_svr)) {
245		/*
246		 * seq # which is the start of data and from that the offset
247		 * into the buffer array.
248		 */
249		a1 = seq - rap->rap_sseq;
250		a2 = MIN(dlen, sizeof(rap->rap_svr));
251		a2 -= a1;
252		s = membuf;
253	} else
254		return 0;
255
256	for (a3 = a1, a4 = a2; (a4 > 0) && (a3 < 19) && (a3 >= 0); a4--,a3++) {
257		rap->rap_sbf |= (1 << a3);
258		rap->rap_svr[a3] = *s++;
259	}
260
261	if ((rap->rap_sbf != 0x7ffff) || (!rap->rap_eos))	/* 19 bits */
262		return 0;
263	rap->rap_sdone = 1;
264
265	s = (u_char *)rap->rap_svr + 11;
266	if (((*s << 8) | *(s + 1)) == RA_ID_ROBUST) {
267		s += 2;
268		rap->rap_srport = (*s << 8) | *(s + 1);
269	}
270
271	ip = fin->fin_ip;
272	swp = ip->ip_p;
273	swa = ip->ip_src;
274	swb = ip->ip_dst;
275
276	ip->ip_p = IPPROTO_UDP;
277	ip->ip_src = nat->nat_ndstip;
278	ip->ip_dst = nat->nat_odstip;
279
280	bcopy((char *)fin, (char *)&fi, sizeof(fi));
281	bzero((char *)tcp2, sizeof(*tcp2));
282	TCP_OFF_A(tcp2, 5);
283	fi.fin_flx |= FI_IGNORE;
284	fi.fin_dp = (char *)tcp2;
285	fi.fin_fr = &raudiofr;
286	fi.fin_dlen = sizeof(*tcp2);
287	fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
288	tcp2->th_win = htons(8192);
289	slen = ip->ip_len;
290	ip->ip_len = htons(fin->fin_hlen + sizeof(*tcp));
291
292	if (((rap->rap_mode & RAP_M_UDP_ROBUST) == RAP_M_UDP_ROBUST) &&
293	    (rap->rap_srport != 0)) {
294		dp = rap->rap_srport;
295		sp = rap->rap_prport;
296		tcp2->th_sport = htons(sp);
297		tcp2->th_dport = htons(dp);
298		fi.fin_data[0] = dp;
299		fi.fin_data[1] = sp;
300		fi.fin_out = 0;
301		MUTEX_ENTER(&softn->ipf_nat_new);
302		nat2 = ipf_nat_add(&fi, nat->nat_ptr, NULL,
303			       NAT_SLAVE|IPN_UDP | (sp ? 0 : SI_W_SPORT),
304			       NAT_OUTBOUND);
305		MUTEX_EXIT(&softn->ipf_nat_new);
306		if (nat2 != NULL) {
307			(void) ipf_nat_proto(&fi, nat2, IPN_UDP);
308			MUTEX_ENTER(&nat2->nat_lock);
309			ipf_nat_update(&fi, nat2);
310			MUTEX_EXIT(&nat2->nat_lock);
311
312			(void) ipf_state_add(softc, &fi, NULL,
313					     (sp ? 0 : SI_W_SPORT));
314		}
315	}
316
317	if ((rap->rap_mode & RAP_M_UDP) == RAP_M_UDP) {
318		sp = rap->rap_plport;
319		tcp2->th_sport = htons(sp);
320		tcp2->th_dport = 0; /* XXX - don't specify remote port */
321		fi.fin_data[0] = sp;
322		fi.fin_data[1] = 0;
323		fi.fin_out = 1;
324		MUTEX_ENTER(&softn->ipf_nat_new);
325		nat2 = ipf_nat_add(&fi, nat->nat_ptr, NULL,
326			       NAT_SLAVE|IPN_UDP|SI_W_DPORT,
327			       NAT_OUTBOUND);
328		MUTEX_EXIT(&softn->ipf_nat_new);
329		if (nat2 != NULL) {
330			(void) ipf_nat_proto(&fi, nat2, IPN_UDP);
331			MUTEX_ENTER(&nat2->nat_lock);
332			ipf_nat_update(&fi, nat2);
333			MUTEX_EXIT(&nat2->nat_lock);
334
335			(void) ipf_state_add(softc, &fi, NULL, SI_W_DPORT);
336		}
337	}
338
339	ip->ip_p = swp;
340	ip->ip_len = slen;
341	ip->ip_src = swa;
342	ip->ip_dst = swb;
343	return 0;
344}
345