1 #include "common.h"
2 #include <ndb.h>
3 #include "smtp.h"	/* to publish dial_string_parse */
4 
5 enum
6 {
7 	Nmx=	16,
8 	Maxstring=	256,
9 };
10 
11 typedef struct Mx	Mx;
12 struct Mx
13 {
14 	char host[256];
15 	char ip[24];
16 	int pref;
17 };
18 static Mx mx[Nmx];
19 
20 Ndb *db;
21 extern int debug;
22 
23 static int	mxlookup(DS*, char*);
24 static int	mxlookup1(DS*, char*);
25 static int	compar(void*, void*);
26 static int	callmx(DS*, char*, char*);
27 static void expand_meta(DS *ds);
28 extern int	cistrcmp(char*, char*);
29 
30 int
31 mxdial(char *addr, char *ddomain, char *gdomain)
32 {
33 	int fd;
34 	DS ds;
35 	char err[Errlen];
36 
37 	addr = netmkaddr(addr, 0, "smtp");
38 	dial_string_parse(addr, &ds);
39 
40 	/* try connecting to destination or any of it's mail routers */
41 	fd = callmx(&ds, addr, ddomain);
42 
43 	/* try our mail gateway */
44 	rerrstr(err, sizeof(err));
45 	if(fd < 0 && gdomain && strstr(err, "can't translate") != 0) {
46 		fprint(2,"dialing %s\n",gdomain);
47 		fd = dial(netmkaddr(gdomain, 0, "smtp"), 0, 0, 0);
48 	}
49 
50 	return fd;
51 }
52 
53 /*
54  *  take an address and return all the mx entries for it,
55  *  most preferred first
56  */
57 static int
58 callmx(DS *ds, char *dest, char *domain)
59 {
60 	int fd, i, nmx;
61 	char addr[Maxstring];
62 
63 	/* get a list of mx entries */
64 	nmx = mxlookup(ds, domain);
65 	if(nmx < 0){
66 		/* dns isn't working, don't just dial */
67 		return -1;
68 	}
69 	if(nmx == 0){
70 		if(debug)
71 			fprint(2, "mxlookup returns nothing\n");
72 		return dial(dest, 0, 0, 0);
73 	}
74 
75 	/* refuse to honor loopback addresses given by dns */
76 	for(i = 0; i < nmx; i++){
77 		if(strcmp(mx[i].ip, "127.0.0.1") == 0){
78 			if(debug)
79 				fprint(2, "mxlookup returns loopback\n");
80 			werrstr("illegal: domain lists 127.0.0.1 as mail server");
81 			return -1;
82 		}
83 	}
84 
85 	/* sort by preference */
86 	if(nmx > 1)
87 		qsort(mx, nmx, sizeof(Mx), compar);
88 
89 	/* dial each one in turn */
90 	for(i = 0; i < nmx; i++){
91 		snprint(addr, sizeof(addr), "%s/%s!%s!%s", ds->netdir, ds->proto,
92 			mx[i].host, ds->service);
93 		if(debug)
94 			fprint(2, "mxdial trying %s\n", addr);
95 		fd = dial(addr, 0, 0, 0);
96 		if(fd >= 0)
97 			return fd;
98 	}
99 	return -1;
100 }
101 
102 /*
103  *  call the dns process and have it try to resolve the mx request
104  *
105  *  this routine knows about the firewall and tries inside and outside
106  *  dns's seperately.
107  */
108 static int
109 mxlookup(DS *ds, char *domain)
110 {
111 	int n;
112 
113 	/* just in case we find no domain name */
114 	strcpy(domain, ds->host);
115 
116 	if(ds->netdir){
117 		n = mxlookup1(ds, domain);
118 	} else {
119 		ds->netdir = "/net";
120 		n = mxlookup1(ds, domain);
121 		if(n == 0) {
122 			ds->netdir = "/net.alt";
123 			n = mxlookup1(ds, domain);
124 		}
125 	}
126 
127 	return n;
128 }
129 
130 static int
131 mxlookup1(DS *ds, char *domain)
132 {
133 	char buf[1024];
134 	char dnsname[Maxstring];
135 	char *fields[4];
136 	int i, n, fd, nmx;
137 
138 	snprint(dnsname, sizeof dnsname, "%s/dns", ds->netdir);
139 
140 	fd = open(dnsname, ORDWR);
141 	if(fd < 0)
142 		return 0;
143 
144 	nmx = 0;
145 	snprint(buf, sizeof(buf), "%s mx", ds->host);
146 	if(debug)
147 		fprint(2, "sending %s '%s'\n", dnsname, buf);
148 	n = write(fd, buf, strlen(buf));
149 	if(n < 0){
150 		rerrstr(buf, sizeof buf);
151 		if(debug)
152 			fprint(2, "dns: %s\n", buf);
153 		if(strstr(buf, "dns failure")){
154 			/* if dns fails for the mx lookup, we have to stop */
155 			close(fd);
156 			return -1;
157 		}
158 	} else {
159 		/*
160 		 *  get any mx entries
161 		 */
162 		seek(fd, 0, 0);
163 		while(nmx < Nmx && (n = read(fd, buf, sizeof(buf)-1)) > 0){
164 			buf[n] = 0;
165 			if(debug)
166 				fprint(2, "dns mx: %s\n", buf);
167 			n = getfields(buf, fields, 4, 1, " \t");
168 			if(n < 4)
169 				continue;
170 
171 			if(strchr(domain, '.') == 0)
172 				strcpy(domain, fields[0]);
173 
174 			strncpy(mx[nmx].host, fields[3], sizeof(mx[n].host)-1);
175 			mx[nmx].pref = atoi(fields[2]);
176 			nmx++;
177 		}
178 		if(debug)
179 			fprint(2, "dns mx; got %d entries\n", nmx);
180 	}
181 
182 	/*
183 	 * no mx record? try name itself.
184 	 */
185 	/*
186 	 * BUG? If domain has no dots, then we used to look up ds->host
187 	 * but return domain instead of ds->host in the list.  Now we return
188 	 * ds->host.  What will this break?
189 	 */
190 	if(nmx == 0){
191 		mx[0].pref = 1;
192 		strncpy(mx[0].host, ds->host, sizeof(mx[0].host));
193 		nmx++;
194 	}
195 
196 	/*
197 	 * look up all ip addresses
198 	 */
199 	for(i = 0; i < nmx; i++){
200 		seek(fd, 0, 0);
201 		snprint(buf, sizeof buf, "%s ip", mx[i].host);
202 		mx[i].ip[0] = 0;
203 		if(write(fd, buf, strlen(buf)) < 0)
204 			goto no;
205 		seek(fd, 0, 0);
206 		if((n = read(fd, buf, sizeof buf-1)) < 0)
207 			goto no;
208 		buf[n] = 0;
209 		if(getfields(buf, fields, 4, 1, " \t") < 3)
210 			goto no;
211 		strncpy(mx[i].ip, fields[2], sizeof(mx[i].ip)-1);
212 		continue;
213 
214 	no:
215 		/* remove mx[i] and go around again */
216 		nmx--;
217 		mx[i] = mx[nmx];
218 		i--;
219 	}
220 	return nmx;		
221 }
222 
223 static int
224 compar(void *a, void *b)
225 {
226 	return ((Mx*)a)->pref - ((Mx*)b)->pref;
227 }
228 
229 /* break up an address to its component parts */
230 void
231 dial_string_parse(char *str, DS *ds)
232 {
233 	char *p, *p2;
234 
235 	strncpy(ds->buf, str, sizeof(ds->buf));
236 	ds->buf[sizeof(ds->buf)-1] = 0;
237 
238 	p = strchr(ds->buf, '!');
239 	if(p == 0) {
240 		ds->netdir = 0;
241 		ds->proto = "net";
242 		ds->host = ds->buf;
243 	} else {
244 		if(*ds->buf != '/'){
245 			ds->netdir = 0;
246 			ds->proto = ds->buf;
247 		} else {
248 			for(p2 = p; *p2 != '/'; p2--)
249 				;
250 			*p2++ = 0;
251 			ds->netdir = ds->buf;
252 			ds->proto = p2;
253 		}
254 		*p = 0;
255 		ds->host = p + 1;
256 	}
257 	ds->service = strchr(ds->host, '!');
258 	if(ds->service)
259 		*ds->service++ = 0;
260 	if(*ds->host == '$')
261 		expand_meta(ds);
262 }
263 
264 #if 0 /* jpc */
265 static void
266 expand_meta(DS *ds)
267 {
268 	char buf[128], cs[128], *net, *p;
269 	int fd, n;
270 
271 	net = ds->netdir;
272 	if(!net)
273 		net = "/net";
274 
275 	if(debug)
276 		fprint(2, "expanding %s!%s\n", net, ds->host);
277 	snprint(cs, sizeof(cs), "%s/cs", net);
278 	if((fd = open(cs, ORDWR)) == -1){
279 		if(debug)
280 			fprint(2, "open %s: %r\n", cs);
281 		syslog(0, "smtp", "cannot open %s: %r", cs);
282 		return;
283 	}
284 
285 	snprint(buf, sizeof(buf), "!ipinfo %s", ds->host+1);	// +1 to skip $
286 	if(write(fd, buf, strlen(buf)) <= 0){
287 		if(debug)
288 			fprint(2, "write %s: %r\n", cs);
289 		syslog(0, "smtp", "%s to %s - write failed: %r", buf, cs);
290 		close(fd);
291 		return;
292 	}
293 
294 	seek(fd, 0, 0);
295 	if((n = read(fd, ds->expand, sizeof(ds->expand)-1)) < 0){
296 		if(debug)
297 			fprint(2, "read %s: %r\n", cs);
298 		syslog(0, "smtp", "%s - read failed: %r", cs);
299 		close(fd);
300 		return;
301 	}
302 	close(fd);
303 
304 	ds->expand[n] = 0;
305 	if((p = strchr(ds->expand, '=')) == nil){
306 		if(debug)
307 			fprint(2, "response %s: %s\n", cs, ds->expand);
308 		syslog(0, "smtp", "%q from %s - bad response: %r", ds->expand, cs);
309 		return;
310 	}
311 	ds->host = p+1;
312 
313 	/* take only first one returned (quasi-bug) */
314 	if((p = strchr(ds->host, ' ')) != nil)
315 		*p = 0;
316 }
317 #endif /* jpc */
318 
319 static void
320 expand_meta(DS *ds)
321 {
322 	Ndb *db;
323 	Ndbs s;
324 	char *sys, *smtpserver;
325 
326 	sys = sysname();
327 	db = ndbopen(unsharp("#9/ndb/local"));
328 	fprint(2,"%s",ds->host);
329 	smtpserver = ndbgetvalue(db, &s, "sys", sys, "smtp", nil);
330 	snprint(ds->host,128,"%s",smtpserver);
331 	fprint(2," exanded to %s\n",ds->host);
332 
333 }