1/*	$NetBSD$	*/
2
3/*++
4/* NAME
5/*	transport 3
6/* SUMMARY
7/*	transport mapping
8/* SYNOPSIS
9/*	#include "transport.h"
10/*
11/*	TRANSPORT_INFO *transport_pre_init(maps_name, maps)
12/*	const char *maps_name;
13/*	const char *maps;
14/*
15/*	void	transport_post_init(info)
16/*	TRANSPORT_INFO *info;
17/*
18/*	int	transport_lookup(info, address, rcpt_domain, channel, nexthop)
19/*	TRANSPORT_INFO *info;
20/*	const char *address;
21/*	const char *rcpt_domain;
22/*	VSTRING *channel;
23/*	VSTRING *nexthop;
24/*
25/*	void	transport_free(info);
26/*	TRANSPORT_INFO * info;
27/* DESCRIPTION
28/*	This module implements access to the table that maps transport
29/*	user@domain addresses to (channel, nexthop) tuples.
30/*
31/*	transport_pre_init() performs initializations that should be
32/*	done before the process enters the chroot jail, and
33/*	before calling transport_lookup().
34/*
35/*	transport_post_init() can be invoked after entering the chroot
36/*	jail, and must be called before before calling transport_lookup().
37/*
38/*	transport_lookup() finds the channel and nexthop for the given
39/*	domain, and returns 1 if something was found.	Otherwise, 0
40/*	is returned.
41/* DIAGNOSTICS
42/*	The global \fIdict_errno\fR is non-zero when the lookup
43/*	should be tried again.
44/* SEE ALSO
45/*	maps(3), multi-dictionary search
46/*	strip_addr(3), strip extension from address
47/*	transport(5), format of transport map
48/* CONFIGURATION PARAMETERS
49/*	transport_maps, names of maps to be searched.
50/* LICENSE
51/* .ad
52/* .fi
53/*	The Secure Mailer license must be distributed with this software.
54/* AUTHOR(S)
55/*	Wietse Venema
56/*	IBM T.J. Watson Research
57/*	P.O. Box 704
58/*	Yorktown Heights, NY 10598, USA
59/*--*/
60
61/* System library. */
62
63#include <sys_defs.h>
64#include <string.h>
65
66/* Utility library. */
67
68#include <msg.h>
69#include <stringops.h>
70#include <mymalloc.h>
71#include <vstring.h>
72#include <split_at.h>
73#include <dict.h>
74#include <events.h>
75
76/* Global library. */
77
78#include <strip_addr.h>
79#include <mail_params.h>
80#include <maps.h>
81#include <match_parent_style.h>
82#include <mail_proto.h>
83
84/* Application-specific. */
85
86#include "transport.h"
87
88static int transport_match_parent_style;
89
90#define STR(x)	vstring_str(x)
91
92static void transport_wildcard_init(TRANSPORT_INFO *);
93
94/* transport_pre_init - pre-jail initialization */
95
96TRANSPORT_INFO *transport_pre_init(const char *transport_maps_name,
97				           const char *transport_maps)
98{
99    TRANSPORT_INFO *tp;
100
101    tp = (TRANSPORT_INFO *) mymalloc(sizeof(*tp));
102    tp->transport_path = maps_create(transport_maps_name, transport_maps,
103				     DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX
104				     | DICT_FLAG_NO_REGSUB);
105    tp->wildcard_channel = tp->wildcard_nexthop = 0;
106    tp->transport_errno = 0;
107    tp->expire = 0;
108    return (tp);
109}
110
111/* transport_post_init - post-jail initialization */
112
113void    transport_post_init(TRANSPORT_INFO *tp)
114{
115    transport_match_parent_style = match_parent_style(VAR_TRANSPORT_MAPS);
116    transport_wildcard_init(tp);
117}
118
119/* transport_free - destroy transport info */
120
121void    transport_free(TRANSPORT_INFO *tp)
122{
123    if (tp->transport_path)
124	maps_free(tp->transport_path);
125    if (tp->wildcard_channel)
126	vstring_free(tp->wildcard_channel);
127    if (tp->wildcard_nexthop)
128	vstring_free(tp->wildcard_nexthop);
129    myfree((char *) tp);
130}
131
132/* update_entry - update from transport table entry */
133
134static void update_entry(const char *new_channel, const char *new_nexthop,
135			         const char *rcpt_domain, VSTRING *channel,
136			         VSTRING *nexthop)
137{
138
139    /*
140     * :[nexthop] means don't change the channel, and don't change the
141     * nexthop unless a non-default nexthop is specified. Thus, a right-hand
142     * side of ":" is the transport table equivalent of a NOOP.
143     */
144    if (*new_channel == 0) {			/* :[nexthop] */
145	if (*new_nexthop != 0)
146	    vstring_strcpy(nexthop, new_nexthop);
147    }
148
149    /*
150     * transport[:[nexthop]] means change the channel, and reset the nexthop
151     * to the default unless a non-default nexthop is specified.
152     */
153    else {
154	vstring_strcpy(channel, new_channel);
155	if (*new_nexthop != 0)
156	    vstring_strcpy(nexthop, new_nexthop);
157	else if (strcmp(STR(channel), MAIL_SERVICE_ERROR) != 0)
158	    vstring_strcpy(nexthop, rcpt_domain);
159	else
160	    vstring_strcpy(nexthop, "Address is undeliverable");
161    }
162}
163
164/* find_transport_entry - look up and parse transport table entry */
165
166static int find_transport_entry(TRANSPORT_INFO *tp, const char *key,
167				        const char *rcpt_domain, int flags,
168				        VSTRING *channel, VSTRING *nexthop)
169{
170    char   *saved_value;
171    const char *host;
172    const char *value;
173
174    /*
175     * Reset previous error history.
176     */
177    dict_errno = 0;
178
179#define FOUND		1
180#define NOTFOUND	0
181
182    /*
183     * Look up an entry with extreme prejudice.
184     *
185     * XXX Should report lookup failure status to caller instead of aborting.
186     */
187    if ((value = maps_find(tp->transport_path, key, flags)) == 0)
188	return (NOTFOUND);
189
190    /*
191     * It would be great if we could specify a recipient address in the
192     * lookup result. Unfortunately, we cannot simply run the result through
193     * a parser that recognizes "transport:user@domain" because the lookup
194     * result can have arbitrary content (especially in the case of the error
195     * mailer).
196     */
197    else {
198	saved_value = mystrdup(value);
199	host = split_at(saved_value, ':');
200	update_entry(saved_value, host ? host : "", rcpt_domain,
201		     channel, nexthop);
202	myfree(saved_value);
203	return (FOUND);
204    }
205}
206
207/* transport_wildcard_init - (re) initialize wild-card lookup result */
208
209static void transport_wildcard_init(TRANSPORT_INFO *tp)
210{
211    VSTRING *channel = vstring_alloc(10);
212    VSTRING *nexthop = vstring_alloc(10);
213
214    /*
215     * Both channel and nexthop may be zero-length strings. Therefore we must
216     * use something else to represent "wild-card does not exist". We use
217     * null VSTRING pointers, for historical reasons.
218     */
219    if (tp->wildcard_channel)
220	vstring_free(tp->wildcard_channel);
221    if (tp->wildcard_nexthop)
222	vstring_free(tp->wildcard_nexthop);
223
224    /*
225     * Technically, the wildcard lookup pattern is redundant. A static map
226     * (keys always match, result is fixed string) could achieve the same:
227     *
228     * transport_maps = hash:/etc/postfix/transport static:xxx:yyy
229     *
230     * But the user interface of such an approach would be less intuitive. We
231     * tolerate the continued existence of wildcard lookup patterns because
232     * of human interface considerations.
233     */
234#define WILDCARD	"*"
235#define FULL		0
236#define PARTIAL		DICT_FLAG_FIXED
237
238    if (find_transport_entry(tp, WILDCARD, "", FULL, channel, nexthop)) {
239	tp->transport_errno = 0;
240	tp->wildcard_channel = channel;
241	tp->wildcard_nexthop = nexthop;
242	if (msg_verbose)
243	    msg_info("wildcard_{chan:hop}={%s:%s}",
244		     vstring_str(channel), vstring_str(nexthop));
245    } else {
246	tp->transport_errno = dict_errno;
247	vstring_free(channel);
248	vstring_free(nexthop);
249	tp->wildcard_channel = 0;
250	tp->wildcard_nexthop = 0;
251    }
252    tp->expire = event_time() + 30;		/* XXX make configurable */
253}
254
255/* transport_lookup - map a transport domain */
256
257int     transport_lookup(TRANSPORT_INFO *tp, const char *addr,
258			         const char *rcpt_domain,
259			         VSTRING *channel, VSTRING *nexthop)
260{
261    char   *stripped_addr;
262    char   *ratsign = 0;
263    const char *name;
264    const char *next;
265    int     found;
266
267#define STREQ(x,y)	(strcmp((x), (y)) == 0)
268#define DISCARD_EXTENSION ((char **) 0)
269
270    /*
271     * The null recipient is rewritten to the local mailer daemon address.
272     */
273    if (*addr == 0) {
274	msg_warn("transport_lookup: null address - skipping table lookup");
275	return (NOTFOUND);
276    }
277
278    /*
279     * Look up the full address with the FULL flag to include regexp maps in
280     * the query.
281     */
282    if ((ratsign = strrchr(addr, '@')) == 0 || ratsign[1] == 0)
283	msg_panic("transport_lookup: bad address: \"%s\"", addr);
284
285    if (find_transport_entry(tp, addr, rcpt_domain, FULL, channel, nexthop))
286	return (FOUND);
287    if (dict_errno != 0)
288	return (NOTFOUND);
289
290    /*
291     * If the full address did not match, and there is an address extension,
292     * look up the stripped address with the PARTIAL flag to avoid matching
293     * partial lookup keys with regular expressions.
294     */
295    if ((stripped_addr = strip_addr(addr, DISCARD_EXTENSION,
296				    *var_rcpt_delim)) != 0) {
297	found = find_transport_entry(tp, stripped_addr, rcpt_domain, PARTIAL,
298				     channel, nexthop);
299
300	myfree(stripped_addr);
301	if (found)
302	    return (FOUND);
303	if (dict_errno != 0)
304	    return (NOTFOUND);
305    }
306
307    /*
308     * If the full and stripped address lookup fails, try domain name lookup.
309     *
310     * Keep stripping domain components until nothing is left or until a
311     * matching entry is found.
312     *
313     * After checking the full domain name, check for .upper.domain, to
314     * distinguish between the parent domain and it's decendants, a la
315     * sendmail and tcp wrappers.
316     *
317     * Before changing the DB lookup result, make a copy first, in order to
318     * avoid DB cache corruption.
319     *
320     * Specify that the lookup key is partial, to avoid matching partial keys
321     * with regular expressions.
322     */
323    for (name = ratsign + 1; *name != 0; name = next) {
324	if (find_transport_entry(tp, name, rcpt_domain, PARTIAL, channel, nexthop))
325	    return (FOUND);
326	if (dict_errno != 0)
327	    return (NOTFOUND);
328	if ((next = strchr(name + 1, '.')) == 0)
329	    break;
330	if (transport_match_parent_style == MATCH_FLAG_PARENT)
331	    next++;
332    }
333
334    /*
335     * Fall back to the wild-card entry.
336     */
337    if (tp->transport_errno || event_time() > tp->expire)
338	transport_wildcard_init(tp);
339    if (tp->transport_errno) {
340	dict_errno = tp->transport_errno;
341	return (NOTFOUND);
342    } else if (tp->wildcard_channel) {
343	update_entry(STR(tp->wildcard_channel), STR(tp->wildcard_nexthop),
344		     rcpt_domain, channel, nexthop);
345	return (FOUND);
346    }
347
348    /*
349     * We really did not find it.
350     */
351    return (NOTFOUND);
352}
353