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