1/*	$NetBSD: ip_irc_pxy.c,v 1.2 2012/02/15 17:55:04 riz Exp $	*/
2
3/*
4 * Copyright (C) 2000-2003 Darren Reed
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * Id: ip_irc_pxy.c,v 2.39.2.9 2008/11/06 21:18:34 darrenr Exp
9 */
10
11#define	IPF_IRC_PROXY
12
13#define	IPF_IRCBUFSZ	96	/* This *MUST* be >= 64! */
14
15
16int ippr_irc_init(void);
17void ippr_irc_fini(void);
18int ippr_irc_new(fr_info_t *, ap_session_t *, nat_t *);
19int ippr_irc_out(fr_info_t *, ap_session_t *, nat_t *);
20int ippr_irc_send(fr_info_t *, nat_t *);
21int ippr_irc_complete(ircinfo_t *, char *, size_t);
22u_short ipf_irc_atoi(char **);
23
24static	frentry_t	ircnatfr;
25
26int	irc_proxy_init = 0;
27
28
29/*
30 * Initialize local structures.
31 */
32int
33ippr_irc_init(void)
34{
35	bzero((char *)&ircnatfr, sizeof(ircnatfr));
36	ircnatfr.fr_ref = 1;
37	ircnatfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
38	MUTEX_INIT(&ircnatfr.fr_lock, "IRC proxy rule lock");
39	irc_proxy_init = 1;
40
41	return 0;
42}
43
44
45void
46ippr_irc_fini(void)
47{
48	if (irc_proxy_init == 1) {
49		MUTEX_DESTROY(&ircnatfr.fr_lock);
50		irc_proxy_init = 0;
51	}
52}
53
54
55const char *ippr_irc_dcctypes[] = {
56	"CHAT ",	/* CHAT chat ipnumber portnumber */
57	"SEND ",	/* SEND filename ipnumber portnumber */
58	"MOVE ",
59	"TSEND ",
60	"SCHAT ",
61	NULL,
62};
63
64
65/*
66 * :A PRIVMSG B :^ADCC CHAT chat 0 0^A\r\n
67 * PRIVMSG B ^ADCC CHAT chat 0 0^A\r\n
68 */
69
70
71int
72ippr_irc_complete(ircinfo_t *ircp, char *buf, size_t len)
73{
74	register char *s, c;
75	register size_t i;
76	u_32_t l;
77	int j, k;
78
79	ircp->irc_ipnum = 0;
80	ircp->irc_port = 0;
81
82	if (len < 31)
83		return 0;
84	s = buf;
85	c = *s++;
86	i = len - 1;
87
88	if ((c != ':') && (c != 'P'))
89		return 0;
90
91	if (c == ':') {
92		/*
93		 * Loosely check that the source is a nickname of some sort
94		 */
95		s++;
96		c = *s;
97		ircp->irc_snick = s;
98		if (!ISALPHA(c))
99			return 0;
100		i--;
101		for (c = *s; !ISSPACE(c) && (i > 0); i--)
102			c = *s++;
103		if (i < 31)
104			return 0;
105		if (c != 'P')
106			return 0;
107	} else
108		ircp->irc_snick = NULL;
109
110	/*
111	 * Check command string
112	 */
113	if (strncmp(s, "PRIVMSG ", 8))
114		return 0;
115	i -= 8;
116	s += 8;
117	c = *s;
118	ircp->irc_dnick = s;
119
120	/*
121	 * Loosely check that the destination is a nickname of some sort
122	 */
123	if (!ISALPHA(c))
124		return 0;
125	for (; !ISSPACE(c) && (i > 0); i--)
126		c = *s++;
127	if (i < 20)
128		return 0;
129	s++,
130	i--;
131
132	/*
133	 * Look for a ^A to start the DCC
134	 */
135	c = *s;
136	if (c == ':') {
137		s++;
138		c = *s;
139	}
140
141	if (strncmp(s, "\001DCC ", 4))
142		return 0;
143
144	i -= 4;
145	s += 4;
146
147	/*
148	 * Check for a recognised DCC command
149	 */
150	for (j = 0, k = 0; ippr_irc_dcctypes[j]; j++) {
151		k = MIN(strlen(ippr_irc_dcctypes[j]), i);
152		if (!strncmp(ippr_irc_dcctypes[j], s, k))
153			break;
154	}
155	if (!ippr_irc_dcctypes[j])
156		return 0;
157
158	ircp->irc_type = s;
159	i -= k;
160	s += k;
161
162	if (i < 11)
163		return 0;
164
165	/*
166	 * Check for the arg
167	 */
168	c = *s;
169	if (ISSPACE(c))
170		return 0;
171	ircp->irc_arg = s;
172	for (; (c != ' ') && (c != '\001') && (i > 0); i--)
173		c = *s++;
174
175	if (c == '\001')	/* In reality a ^A can quote another ^A...*/
176		return 0;
177
178	if (i < 5)
179		return 0;
180
181	s++;
182	i--;
183	c = *s;
184	if (!ISDIGIT(c))
185		return 0;
186	ircp->irc_addr = s;
187	/*
188	 * Get the IP#
189	 */
190	for (l = 0; ISDIGIT(c) && (i > 0); i--) {
191		l *= 10;
192		l += c - '0';
193		c = *s++;
194	}
195
196	if (i < 4)
197		return 0;
198
199	if (c != ' ')
200		return 0;
201
202	ircp->irc_ipnum = l;
203	s++;
204	i--;
205	c = *s;
206	if (!ISDIGIT(c))
207		return 0;
208	/*
209	 * Get the port#
210	 */
211	for (l = 0; ISDIGIT(c) && (i > 0); i--) {
212		l *= 10;
213		l += c - '0';
214		c = *s++;
215	}
216	if (i < 3)
217		return 0;
218	if (strncmp(s, "\001\r\n", 3))
219		return 0;
220	s += 3;
221	ircp->irc_len = s - buf;
222	ircp->irc_port = l;
223	return 1;
224}
225
226
227int
228ippr_irc_new(fr_info_t *fin, ap_session_t *aps, nat_t *nat)
229{
230	ircinfo_t *irc;
231
232	KMALLOC(irc, ircinfo_t *);
233	if (irc == NULL)
234		return -1;
235
236	fin = fin;	/* LINT */
237	nat = nat;	/* LINT */
238
239	aps->aps_data = irc;
240	aps->aps_psiz = sizeof(ircinfo_t);
241
242	bzero((char *)irc, sizeof(*irc));
243	return 0;
244}
245
246
247int
248ippr_irc_send(fr_info_t *fin, nat_t *nat)
249{
250	char ctcpbuf[IPF_IRCBUFSZ], newbuf[IPF_IRCBUFSZ];
251	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
252	int off, inc = 0, i, dlen;
253	size_t nlen = 0, olen;
254	struct in_addr swip;
255	u_short a5, sp;
256	ircinfo_t *irc;
257	fr_info_t fi;
258	nat_t *nat2;
259	u_int a1;
260	ip_t *ip;
261	mb_t *m;
262#ifdef	MENTAT
263	mb_t *m1;
264#endif
265
266	m = fin->fin_m;
267	ip = fin->fin_ip;
268	tcp = (tcphdr_t *)fin->fin_dp;
269	bzero(ctcpbuf, sizeof(ctcpbuf));
270	off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
271
272#ifdef __sgi
273	dlen = fin->fin_plen - off;
274#else
275	dlen = MSGDSIZE(m) - off;
276#endif
277	if (dlen <= 0)
278		return 0;
279	COPYDATA(m, off, MIN(sizeof(ctcpbuf), dlen), ctcpbuf);
280
281	if (dlen <= 0)
282		return 0;
283	ctcpbuf[sizeof(ctcpbuf) - 1] = '\0';
284	*newbuf = '\0';
285
286	irc = nat->nat_aps->aps_data;
287	if (ippr_irc_complete(irc, ctcpbuf, dlen) == 0)
288		return 0;
289
290	/*
291	 * check that IP address in the PORT/PASV reply is the same as the
292	 * sender of the command - prevents using PORT for port scanning.
293	 */
294	if (irc->irc_ipnum != ntohl(nat->nat_inip.s_addr))
295		return 0;
296
297	a5 = irc->irc_port;
298
299	/*
300	 * Calculate new address parts for the DCC command
301	 */
302	a1 = ntohl(ip->ip_src.s_addr);
303	olen = irc->irc_len;
304	i = irc->irc_addr - ctcpbuf;
305	i++;
306	(void) strncpy(newbuf, ctcpbuf, i);
307	/* DO NOT change these! */
308#if defined(SNPRINTF) && defined(KERNEL)
309	SNPRINTF(newbuf, sizeof(newbuf) - i, "%u %u\001\r\n", a1, a5);
310#else
311	(void) sprintf(newbuf, "%u %u\001\r\n", a1, a5);
312#endif
313
314	nlen = strlen(newbuf);
315	inc = nlen - olen;
316
317	if ((inc + ip->ip_len) > 65535)
318		return 0;
319
320#ifdef	MENTAT
321	for (m1 = m; m1->b_cont; m1 = m1->b_cont)
322		;
323	if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
324		mblk_t *nm;
325
326		/* alloc enough to keep same trailer space for lower driver */
327		nm = allocb(nlen, BPRI_MED);
328		PANIC((!nm),("ippr_irc_out: allocb failed"));
329
330		nm->b_band = m1->b_band;
331		nm->b_wptr += nlen;
332
333		m1->b_wptr -= olen;
334		PANIC((m1->b_wptr < m1->b_rptr),
335		      ("ippr_irc_out: cannot handle fragmented data block"));
336
337		linkb(m1, nm);
338	} else {
339# if SOLARIS && defined(ICK_VALID)
340		if (m1->b_datap->db_struiolim == m1->b_wptr)
341			m1->b_datap->db_struiolim += inc;
342		m1->b_datap->db_struioflag &= ~STRUIO_IP;
343# endif
344		m1->b_wptr += inc;
345	}
346#else
347	if (inc < 0)
348		m_adj(m, inc);
349	/* the mbuf chain will be extended if necessary by m_copyback() */
350#endif
351	COPYBACK(m, off, nlen, newbuf);
352
353	if (inc != 0) {
354#if defined(MENTAT) || defined(__sgi)
355		register u_32_t	sum1, sum2;
356
357		sum1 = ip->ip_len;
358		sum2 = ip->ip_len + inc;
359
360		/* Because ~1 == -2, We really need ~1 == -1 */
361		if (sum1 > sum2)
362			sum2--;
363		sum2 -= sum1;
364		sum2 = (sum2 & 0xffff) + (sum2 >> 16);
365
366		fix_outcksum(fin, &ip->ip_sum, sum2);
367#endif
368		ip->ip_len += inc;
369	}
370
371	/*
372	 * Add skeleton NAT entry for connection which will come back the
373	 * other way.
374	 */
375	sp = htons(a5);
376	/*
377	 * Don't allow the PORT command to specify a port < 1024 due to
378	 * security crap.
379	 */
380	if (ntohs(sp) < 1024)
381		return 0;
382
383	/*
384	 * The server may not make the connection back from port 20, but
385	 * it is the most likely so use it here to check for a conflicting
386	 * mapping.
387	 */
388	bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
389	fi.fin_data[0] = sp;
390	fi.fin_data[1] = fin->fin_data[1];
391	nat2 = nat_outlookup(fin, IPN_TCP, nat->nat_p, nat->nat_inip,
392			     ip->ip_dst);
393	if (nat2 == NULL) {
394		bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
395		bzero((char *)tcp2, sizeof(*tcp2));
396		tcp2->th_win = htons(8192);
397		tcp2->th_sport = sp;
398		tcp2->th_dport = 0; /* XXX - don't specify remote port */
399		fi.fin_data[0] = ntohs(sp);
400		fi.fin_data[1] = 0;
401		fi.fin_dp = (char *)tcp2;
402		fi.fin_fr = &ircnatfr;
403		fi.fin_dlen = sizeof(*tcp2);
404		fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
405		swip = ip->ip_src;
406		ip->ip_src = nat->nat_inip;
407		MUTEX_ENTER(&ipf_nat_new);
408		nat2 = nat_new(&fi, nat->nat_ptr, NULL,
409			       NAT_SLAVE|IPN_TCP|SI_W_DPORT, NAT_OUTBOUND);
410		MUTEX_EXIT(&ipf_nat_new);
411		if (nat2 != NULL) {
412			(void) nat_proto(&fi, nat2, 0);
413			MUTEX_ENTER(&nat2->nat_lock);
414			nat_update(&fi, nat2);
415			MUTEX_EXIT(&nat2->nat_lock);
416
417			(void) fr_addstate(&fi, NULL, SI_W_DPORT);
418		}
419		ip->ip_src = swip;
420	}
421	return inc;
422}
423
424
425int
426ippr_irc_out(fr_info_t *fin, ap_session_t *aps, nat_t *nat)
427{
428	aps = aps;	/* LINT */
429	return ippr_irc_send(fin, nat);
430}
431