1/*
2 * Copyright (C) 2012 by Darren Reed.
3 *
4 * See the IPFILTER.LICENCE file for details on licencing.
5 *
6 * $Id$
7 */
8
9#define	IPF_IRC_PROXY
10
11#define	IPF_IRCBUFSZ	96	/* This *MUST* be >= 64! */
12
13
14void ipf_p_irc_main_load(void);
15void ipf_p_irc_main_unload(void);
16int ipf_p_irc_new(void *, fr_info_t *, ap_session_t *, nat_t *);
17int ipf_p_irc_out(void *, fr_info_t *, ap_session_t *, nat_t *);
18int ipf_p_irc_send(fr_info_t *, nat_t *);
19int ipf_p_irc_complete(ircinfo_t *, char *, size_t);
20u_short ipf_irc_atoi(char **);
21
22static	frentry_t	ircnatfr;
23
24int	irc_proxy_init = 0;
25
26
27/*
28 * Initialize local structures.
29 */
30void
31ipf_p_irc_main_load()
32{
33	bzero((char *)&ircnatfr, sizeof(ircnatfr));
34	ircnatfr.fr_ref = 1;
35	ircnatfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
36	MUTEX_INIT(&ircnatfr.fr_lock, "IRC proxy rule lock");
37	irc_proxy_init = 1;
38}
39
40
41void
42ipf_p_irc_main_unload()
43{
44	if (irc_proxy_init == 1) {
45		MUTEX_DESTROY(&ircnatfr.fr_lock);
46		irc_proxy_init = 0;
47	}
48}
49
50
51const char *ipf_p_irc_dcctypes[] = {
52	"CHAT ",	/* CHAT chat ipnumber portnumber */
53	"SEND ",	/* SEND filename ipnumber portnumber */
54	"MOVE ",
55	"TSEND ",
56	"SCHAT ",
57	NULL,
58};
59
60
61/*
62 * :A PRIVMSG B :^ADCC CHAT chat 0 0^A\r\n
63 * PRIVMSG B ^ADCC CHAT chat 0 0^A\r\n
64 */
65
66
67int
68ipf_p_irc_complete(ircp, buf, len)
69	ircinfo_t *ircp;
70	char *buf;
71	size_t len;
72{
73	register char *s, c;
74	register size_t i;
75	u_32_t l;
76	int j, k;
77
78	ircp->irc_ipnum = 0;
79	ircp->irc_port = 0;
80
81	if (len < 31)
82		return 0;
83	s = buf;
84	c = *s++;
85	i = len - 1;
86
87	if ((c != ':') && (c != 'P'))
88		return 0;
89
90	if (c == ':') {
91		/*
92		 * Loosely check that the source is a nickname of some sort
93		 */
94		s++;
95		c = *s;
96		ircp->irc_snick = s;
97		if (!ISALPHA(c))
98			return 0;
99		i--;
100		for (c = *s; !ISSPACE(c) && (i > 0); i--)
101			c = *s++;
102		if (i < 31)
103			return 0;
104		if (c != 'P')
105			return 0;
106	} else
107		ircp->irc_snick = NULL;
108
109	/*
110	 * Check command string
111	 */
112	if (strncmp(s, "PRIVMSG ", 8))
113		return 0;
114	i -= 8;
115	s += 8;
116	c = *s;
117	ircp->irc_dnick = s;
118
119	/*
120	 * Loosely check that the destination is a nickname of some sort
121	 */
122	if (!ISALPHA(c))
123		return 0;
124	for (; !ISSPACE(c) && (i > 0); i--)
125		c = *s++;
126	if (i < 20)
127		return 0;
128	s++,
129	i--;
130
131	/*
132	 * Look for a ^A to start the DCC
133	 */
134	c = *s;
135	if (c == ':') {
136		s++;
137		c = *s;
138	}
139
140	if (strncmp(s, "\001DCC ", 4))
141		return 0;
142
143	i -= 4;
144	s += 4;
145
146	/*
147	 * Check for a recognised DCC command
148	 */
149	for (j = 0, k = 0; ipf_p_irc_dcctypes[j]; j++) {
150		k = MIN(strlen(ipf_p_irc_dcctypes[j]), i);
151		if (!strncmp(ipf_p_irc_dcctypes[j], s, k))
152			break;
153	}
154	if (!ipf_p_irc_dcctypes[j])
155		return 0;
156
157	ircp->irc_type = s;
158	i -= k;
159	s += k;
160
161	if (i < 11)
162		return 0;
163
164	/*
165	 * Check for the arg
166	 */
167	c = *s;
168	if (ISSPACE(c))
169		return 0;
170	ircp->irc_arg = s;
171	for (; (c != ' ') && (c != '\001') && (i > 0); i--)
172		c = *s++;
173
174	if (c == '\001')	/* In reality a ^A can quote another ^A...*/
175		return 0;
176
177	if (i < 5)
178		return 0;
179
180	s++;
181	i--;
182	c = *s;
183	if (!ISDIGIT(c))
184		return 0;
185	ircp->irc_addr = s;
186	/*
187	 * Get the IP#
188	 */
189	for (l = 0; ISDIGIT(c) && (i > 0); i--) {
190		l *= 10;
191		l += c - '0';
192		c = *s++;
193	}
194
195	if (i < 4)
196		return 0;
197
198	if (c != ' ')
199		return 0;
200
201	ircp->irc_ipnum = l;
202	s++;
203	i--;
204	c = *s;
205	if (!ISDIGIT(c))
206		return 0;
207	/*
208	 * Get the port#
209	 */
210	for (l = 0; ISDIGIT(c) && (i > 0); i--) {
211		l *= 10;
212		l += c - '0';
213		c = *s++;
214	}
215	if (i < 3)
216		return 0;
217	if (strncmp(s, "\001\r\n", 3))
218		return 0;
219	s += 3;
220	ircp->irc_len = s - buf;
221	ircp->irc_port = l;
222	return 1;
223}
224
225
226int
227ipf_p_irc_new(arg, fin, aps, nat)
228	void *arg;
229	fr_info_t *fin;
230	ap_session_t *aps;
231	nat_t *nat;
232{
233	ircinfo_t *irc;
234
235	if (fin->fin_v != 4)
236		return -1;
237
238	KMALLOC(irc, ircinfo_t *);
239	if (irc == NULL)
240		return -1;
241
242	nat = nat;	/* LINT */
243
244	aps->aps_data = irc;
245	aps->aps_psiz = sizeof(ircinfo_t);
246
247	bzero((char *)irc, sizeof(*irc));
248	return 0;
249}
250
251
252int
253ipf_p_irc_send(fin, nat)
254	fr_info_t *fin;
255	nat_t *nat;
256{
257	char ctcpbuf[IPF_IRCBUFSZ], newbuf[IPF_IRCBUFSZ];
258	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
259	int off, inc = 0, i, dlen;
260	ipf_main_softc_t *softc;
261	size_t nlen = 0, olen;
262	struct in_addr swip;
263	u_short a5, sp;
264	ircinfo_t *irc;
265	fr_info_t fi;
266	nat_t *nat2;
267	u_int a1;
268	ip_t *ip;
269	mb_t *m;
270#if SOLARIS
271	mb_t *m1;
272#endif
273	softc = fin->fin_main_soft;
274
275	m = fin->fin_m;
276	ip = fin->fin_ip;
277	tcp = (tcphdr_t *)fin->fin_dp;
278	bzero(ctcpbuf, sizeof(ctcpbuf));
279	off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
280
281	dlen = MSGDSIZE(m) - off;
282	if (dlen <= 0)
283		return 0;
284	COPYDATA(m, off, MIN(sizeof(ctcpbuf), dlen), ctcpbuf);
285
286	if (dlen <= 0)
287		return 0;
288	ctcpbuf[sizeof(ctcpbuf) - 1] = '\0';
289	*newbuf = '\0';
290
291	irc = nat->nat_aps->aps_data;
292	if (ipf_p_irc_complete(irc, ctcpbuf, dlen) == 0)
293		return 0;
294
295	/*
296	 * check that IP address in the DCC reply is the same as the
297	 * sender of the command - prevents use for port scanning.
298	 */
299	if (irc->irc_ipnum != ntohl(nat->nat_osrcaddr))
300		return 0;
301
302	a5 = irc->irc_port;
303
304	/*
305	 * Calculate new address parts for the DCC command
306	 */
307	a1 = ntohl(ip->ip_src.s_addr);
308	olen = irc->irc_len;
309	i = irc->irc_addr - ctcpbuf;
310	i++;
311	(void) strncpy(newbuf, ctcpbuf, i);
312	/* DO NOT change these! */
313#if defined(SNPRINTF) && defined(KERNEL)
314	SNPRINTF(newbuf, sizeof(newbuf) - i, "%u %u\001\r\n", a1, a5);
315#else
316	(void) sprintf(newbuf, "%u %u\001\r\n", a1, a5);
317#endif
318
319	nlen = strlen(newbuf);
320	inc = nlen - olen;
321
322	if ((inc + fin->fin_plen) > 65535)
323		return 0;
324
325#if SOLARIS
326	for (m1 = m; m1->b_cont; m1 = m1->b_cont)
327		;
328	if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
329		mblk_t *nm;
330
331		/* alloc enough to keep same trailer space for lower driver */
332		nm = allocb(nlen, BPRI_MED);
333		PANIC((!nm),("ipf_p_irc_out: allocb failed"));
334
335		nm->b_band = m1->b_band;
336		nm->b_wptr += nlen;
337
338		m1->b_wptr -= olen;
339		PANIC((m1->b_wptr < m1->b_rptr),
340		      ("ipf_p_irc_out: cannot handle fragmented data block"));
341
342		linkb(m1, nm);
343	} else {
344# if SOLARIS && defined(ICK_VALID)
345		if (m1->b_datap->db_struiolim == m1->b_wptr)
346			m1->b_datap->db_struiolim += inc;
347		m1->b_datap->db_struioflag &= ~STRUIO_IP;
348# endif
349		m1->b_wptr += inc;
350	}
351#else
352	if (inc < 0)
353		m_adj(m, inc);
354	/* the mbuf chain will be extended if necessary by m_copyback() */
355#endif
356	COPYBACK(m, off, nlen, newbuf);
357	fin->fin_flx |= FI_DOCKSUM;
358
359	if (inc != 0) {
360#if SOLARIS
361		register u_32_t	sum1, sum2;
362
363		sum1 = fin->fin_plen;
364		sum2 = fin->fin_plen + inc;
365
366		/* Because ~1 == -2, We really need ~1 == -1 */
367		if (sum1 > sum2)
368			sum2--;
369		sum2 -= sum1;
370		sum2 = (sum2 & 0xffff) + (sum2 >> 16);
371
372		ipf_fix_outcksum(0, &ip->ip_sum, sum2, 0);
373#endif
374		fin->fin_plen += inc;
375		ip->ip_len = htons(fin->fin_plen);
376		fin->fin_dlen += inc;
377	}
378
379	/*
380	 * Add skeleton NAT entry for connection which will come back the
381	 * other way.
382	 */
383	sp = htons(a5);
384	/*
385	 * Don't allow the PORT command to specify a port < 1024 due to
386	 * security crap.
387	 */
388	if (ntohs(sp) < 1024)
389		return 0;
390
391	/*
392	 * The server may not make the connection back from port 20, but
393	 * it is the most likely so use it here to check for a conflicting
394	 * mapping.
395	 */
396	bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
397	fi.fin_data[0] = sp;
398	fi.fin_data[1] = fin->fin_data[1];
399	nat2 = ipf_nat_outlookup(fin, IPN_TCP, nat->nat_pr[1], nat->nat_nsrcip,
400			     ip->ip_dst);
401	if (nat2 == NULL) {
402#ifdef USE_MUTEXES
403		ipf_nat_softc_t *softn = softc->ipf_nat_soft;
404#endif
405
406		bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
407		bzero((char *)tcp2, sizeof(*tcp2));
408		tcp2->th_win = htons(8192);
409		tcp2->th_sport = sp;
410		tcp2->th_dport = 0; /* XXX - don't specify remote port */
411		fi.fin_data[0] = ntohs(sp);
412		fi.fin_data[1] = 0;
413		fi.fin_dp = (char *)tcp2;
414		fi.fin_fr = &ircnatfr;
415		fi.fin_dlen = sizeof(*tcp2);
416		fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
417		swip = ip->ip_src;
418		ip->ip_src = nat->nat_nsrcip;
419		MUTEX_ENTER(&softn->ipf_nat_new);
420		nat2 = ipf_nat_add(&fi, nat->nat_ptr, NULL,
421			       NAT_SLAVE|IPN_TCP|SI_W_DPORT, NAT_OUTBOUND);
422		MUTEX_EXIT(&softn->ipf_nat_new);
423		if (nat2 != NULL) {
424			(void) ipf_nat_proto(&fi, nat2, 0);
425			MUTEX_ENTER(&nat2->nat_lock);
426			ipf_nat_update(&fi, nat2);
427			MUTEX_EXIT(&nat2->nat_lock);
428
429			(void) ipf_state_add(softc, &fi, NULL, SI_W_DPORT);
430		}
431		ip->ip_src = swip;
432	}
433	return inc;
434}
435
436
437int
438ipf_p_irc_out(arg, fin, aps, nat)
439	void *arg;
440	fr_info_t *fin;
441	ap_session_t *aps;
442	nat_t *nat;
443{
444	aps = aps;	/* LINT */
445	return ipf_p_irc_send(fin, nat);
446}
447