1/*	$FreeBSD$	*/
2
3/*
4 * Copyright (C) 1998-2003 by Darren Reed
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * $Id: ip_rcmd_pxy.c,v 1.41.2.7 2006/07/14 06:12:18 darrenr Exp $
9 *
10 * Simple RCMD transparent proxy for in-kernel use.  For use with the NAT
11 * code.
12 * $FreeBSD$
13 */
14
15#define	IPF_RCMD_PROXY
16
17
18int ippr_rcmd_init __P((void));
19void ippr_rcmd_fini __P((void));
20int ippr_rcmd_new __P((fr_info_t *, ap_session_t *, nat_t *));
21int ippr_rcmd_out __P((fr_info_t *, ap_session_t *, nat_t *));
22int ippr_rcmd_in __P((fr_info_t *, ap_session_t *, nat_t *));
23u_short ipf_rcmd_atoi __P((char *));
24int ippr_rcmd_portmsg __P((fr_info_t *, ap_session_t *, nat_t *));
25
26static	frentry_t	rcmdfr;
27
28int	rcmd_proxy_init = 0;
29
30
31/*
32 * RCMD application proxy initialization.
33 */
34int ippr_rcmd_init()
35{
36	bzero((char *)&rcmdfr, sizeof(rcmdfr));
37	rcmdfr.fr_ref = 1;
38	rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
39	MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock");
40	rcmd_proxy_init = 1;
41
42	return 0;
43}
44
45
46void ippr_rcmd_fini()
47{
48	if (rcmd_proxy_init == 1) {
49		MUTEX_DESTROY(&rcmdfr.fr_lock);
50		rcmd_proxy_init = 0;
51	}
52}
53
54
55/*
56 * Setup for a new RCMD proxy.
57 */
58int ippr_rcmd_new(fin, aps, nat)
59fr_info_t *fin;
60ap_session_t *aps;
61nat_t *nat;
62{
63	tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
64
65	fin = fin;	/* LINT */
66	nat = nat;	/* LINT */
67
68	aps->aps_psiz = sizeof(u_32_t);
69	KMALLOCS(aps->aps_data, u_32_t *, sizeof(u_32_t));
70	if (aps->aps_data == NULL) {
71#ifdef IP_RCMD_PROXY_DEBUG
72		printf("ippr_rcmd_new:KMALLOCS(%d) failed\n", sizeof(u_32_t));
73#endif
74		return -1;
75	}
76	*(u_32_t *)aps->aps_data = 0;
77	aps->aps_sport = tcp->th_sport;
78	aps->aps_dport = tcp->th_dport;
79	return 0;
80}
81
82
83/*
84 * ipf_rcmd_atoi - implement a simple version of atoi
85 */
86u_short ipf_rcmd_atoi(ptr)
87char *ptr;
88{
89	register char *s = ptr, c;
90	register u_short i = 0;
91
92	while (((c = *s++) != '\0') && ISDIGIT(c)) {
93		i *= 10;
94		i += c - '0';
95	}
96	return i;
97}
98
99
100int ippr_rcmd_portmsg(fin, aps, nat)
101fr_info_t *fin;
102ap_session_t *aps;
103nat_t *nat;
104{
105	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
106	struct in_addr swip, swip2;
107	int off, dlen, nflags;
108	char portbuf[8], *s;
109	fr_info_t fi;
110	u_short sp;
111	nat_t *nat2;
112	ip_t *ip;
113	mb_t *m;
114
115	tcp = (tcphdr_t *)fin->fin_dp;
116
117	if (tcp->th_flags & TH_SYN) {
118		*(u_32_t *)aps->aps_data = htonl(ntohl(tcp->th_seq) + 1);
119		return 0;
120	}
121
122	if ((*(u_32_t *)aps->aps_data != 0) &&
123	    (tcp->th_seq != *(u_32_t *)aps->aps_data))
124		return 0;
125
126	m = fin->fin_m;
127	ip = fin->fin_ip;
128	off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
129
130#ifdef __sgi
131	dlen = fin->fin_plen - off;
132#else
133	dlen = MSGDSIZE(m) - off;
134#endif
135	if (dlen <= 0)
136		return 0;
137
138	bzero(portbuf, sizeof(portbuf));
139	COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf);
140
141	portbuf[sizeof(portbuf) - 1] = '\0';
142	s = portbuf;
143	sp = ipf_rcmd_atoi(s);
144	if (sp == 0) {
145#ifdef IP_RCMD_PROXY_DEBUG
146		printf("ippr_rcmd_portmsg:sp == 0 dlen %d [%s]\n",
147		       dlen, portbuf);
148#endif
149		return 0;
150	}
151
152	/*
153	 * Add skeleton NAT entry for connection which will come back the
154	 * other way.
155	 */
156	bcopy((char *)fin, (char *)&fi, sizeof(fi));
157	fi.fin_state = NULL;
158	fi.fin_nat = NULL;
159	fi.fin_flx |= FI_IGNORE;
160	fi.fin_data[0] = sp;
161	fi.fin_data[1] = 0;
162	if (nat->nat_dir == NAT_OUTBOUND)
163		nat2 = nat_outlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
164				     nat->nat_inip, nat->nat_oip);
165	else
166		nat2 = nat_inlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
167				    nat->nat_inip, nat->nat_oip);
168	if (nat2 == NULL) {
169		int slen;
170
171		slen = ip->ip_len;
172		ip->ip_len = fin->fin_hlen + sizeof(*tcp);
173		bzero((char *)tcp2, sizeof(*tcp2));
174		tcp2->th_win = htons(8192);
175		tcp2->th_sport = htons(sp);
176		tcp2->th_dport = 0; /* XXX - don't specify remote port */
177		TCP_OFF_A(tcp2, 5);
178		tcp2->th_flags = TH_SYN;
179		fi.fin_dp = (char *)tcp2;
180		fi.fin_fr = &rcmdfr;
181		fi.fin_dlen = sizeof(*tcp2);
182		fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
183		fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
184		nflags = NAT_SLAVE|IPN_TCP|SI_W_DPORT;
185
186		swip = ip->ip_src;
187		swip2 = ip->ip_dst;
188
189		if (nat->nat_dir == NAT_OUTBOUND) {
190			fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
191			ip->ip_src = nat->nat_inip;
192		} else {
193			fi.fin_fi.fi_saddr = nat->nat_oip.s_addr;
194			ip->ip_src = nat->nat_oip;
195			nflags |= NAT_NOTRULEPORT;
196		}
197
198		nat2 = nat_new(&fi, nat->nat_ptr, NULL, nflags, nat->nat_dir);
199
200		if (nat2 != NULL) {
201			(void) nat_proto(&fi, nat2, IPN_TCP);
202			nat_update(&fi, nat2, nat2->nat_ptr);
203			fi.fin_ifp = NULL;
204			if (nat->nat_dir == NAT_INBOUND) {
205				fi.fin_fi.fi_daddr = nat->nat_inip.s_addr;
206				ip->ip_dst = nat->nat_inip;
207			}
208			(void) fr_addstate(&fi, NULL, SI_W_DPORT);
209			if (fi.fin_state != NULL)
210				fr_statederef((ipstate_t **)&fi.fin_state);
211		}
212		ip->ip_len = slen;
213		ip->ip_src = swip;
214		ip->ip_dst = swip2;
215	}
216	return 0;
217}
218
219
220int ippr_rcmd_out(fin, aps, nat)
221fr_info_t *fin;
222ap_session_t *aps;
223nat_t *nat;
224{
225	if (nat->nat_dir == NAT_OUTBOUND)
226		return ippr_rcmd_portmsg(fin, aps, nat);
227	return 0;
228}
229
230
231int ippr_rcmd_in(fin, aps, nat)
232fr_info_t *fin;
233ap_session_t *aps;
234nat_t *nat;
235{
236	if (nat->nat_dir == NAT_INBOUND)
237		return ippr_rcmd_portmsg(fin, aps, nat);
238	return 0;
239}
240