1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
|
#include "common.h"
#include <ndb.h>
#include "smtp.h" /* to publish dial_string_parse */
#include <ip.h>
#include <thread.h>
enum
{
Nmx= 16,
Maxstring= 256
};
typedef struct Mx Mx;
struct Mx
{
char host[256];
char ip[24];
int pref;
};
static Mx mx[Nmx];
Ndb *db;
extern int debug;
static int mxlookup(DS*, char*);
static int compar(const void*, const void*);
static int callmx(DS*, char*, char*);
static void expand_meta(DS *ds);
extern int cistrcmp(char*, char*);
/* Taken from imapdial, replaces tlsclient call with stunnel */
static int
smtpdial(char *server)
{
int p[2];
int fd[3];
char *tmp;
char *fpath;
if(pipe(p) < 0)
return -1;
fd[0] = dup(p[0], -1);
fd[1] = dup(p[0], -1);
fd[2] = dup(2, -1);
#ifdef PLAN9PORT
tmp = smprint("%s:587", server);
fpath = searchpath("stunnel3");
if (!fpath) {
werrstr("stunnel not found. it is required for tls support.");
return -1;
}
if(threadspawnl(fd, fpath, "stunnel", "-n", "smtp" , "-c", "-r", tmp, nil) < 0) {
#else
tmp = smprint("tcp!%s!587", server);
if(threadspawnl(fd, "/bin/tlsclient", "tlsclient", tmp, nil) < 0){
#endif
free(tmp);
close(p[0]);
close(p[1]);
close(fd[0]);
close(fd[1]);
close(fd[2]);
return -1;
}
free(tmp);
close(p[0]);
return p[1];
}
int
mxdial(char *addr, char *ddomain, char *gdomain)
{
int fd;
DS ds;
char err[Errlen];
addr = netmkaddr(addr, 0, "smtp");
dial_string_parse(addr, &ds);
/* try connecting to destination or any of it's mail routers */
fd = callmx(&ds, addr, ddomain);
/* try our mail gateway */
rerrstr(err, sizeof(err));
if(fd < 0 && gdomain && strstr(err, "can't translate") != 0)
fd = dial(netmkaddr(gdomain, 0, "smtp"), 0, 0, 0);
return fd;
}
static int
timeout(void *v, char *msg)
{
USED(v);
if(strstr(msg, "alarm"))
return 1;
return 0;
}
/*
* take an address and return all the mx entries for it,
* most preferred first
*/
static int
callmx(DS *ds, char *dest, char *domain)
{
int fd, i, nmx;
char addr[Maxstring];
/* get a list of mx entries */
nmx = mxlookup(ds, domain);
if(nmx < 0){
/* dns isn't working, don't just dial */
return -1;
}
if(nmx == 0){
if(debug)
fprint(2, "mxlookup returns nothing\n");
return dial(dest, 0, 0, 0);
}
/* refuse to honor loopback addresses given by dns */
for(i = 0; i < nmx; i++){
if(strcmp(mx[i].ip, "127.0.0.1") == 0){
if(debug)
fprint(2, "mxlookup returns loopback\n");
werrstr("illegal: domain lists 127.0.0.1 as mail server");
return -1;
}
}
/* sort by preference */
if(nmx > 1)
qsort(mx, nmx, sizeof(Mx), compar);
if(debug){
for(i=0; i<nmx; i++)
print("%s %d\n", mx[i].host, mx[i].pref);
}
/* dial each one in turn */
for(i = 0; i < nmx; i++){
#ifdef PLAN9PORT
snprint(addr, sizeof(addr), "%s", mx[i].host);
#else
snprint(addr, sizeof(addr), "%s!%s!%s", ds->proto,
mx[i].host, ds->service);
#endif
if(debug)
fprint(2, "mxdial trying %s (%d)\n", addr, i);
atnotify(timeout, 1);
alarm(10*1000);
#ifdef PLAN9PORT
fd = smtpdial(addr);
#else
fd = dial(addr, 0, 0, 0);
#endif
alarm(0);
atnotify(timeout, 0);
if(fd >= 0)
return fd;
}
return -1;
}
/*
* use dns to resolve the mx request
*/
static int
mxlookup(DS *ds, char *domain)
{
int i, n, nmx;
Ndbtuple *t, *tmx, *tpref, *tip;
strcpy(domain, ds->host);
ds->netdir = "/net";
nmx = 0;
if((t = dnsquery(nil, ds->host, "mx")) != nil){
for(tmx=t; (tmx=ndbfindattr(tmx->entry, nil, "mx")) != nil && nmx<Nmx; ){
for(tpref=tmx->line; tpref != tmx; tpref=tpref->line){
if(strcmp(tpref->attr, "pref") == 0){
strncpy(mx[nmx].host, tmx->val, sizeof(mx[n].host)-1);
mx[nmx].pref = atoi(tpref->val);
nmx++;
break;
}
}
}
ndbfree(t);
}
/*
* no mx record? try name itself.
*/
/*
* BUG? If domain has no dots, then we used to look up ds->host
* but return domain instead of ds->host in the list. Now we return
* ds->host. What will this break?
*/
if(nmx == 0){
mx[0].pref = 1;
strncpy(mx[0].host, ds->host, sizeof(mx[0].host));
nmx++;
}
/*
* look up all ip addresses
*/
for(i = 0; i < nmx; i++){
if((t = dnsquery(nil, mx[i].host, "ip")) == nil)
goto no;
if((tip = ndbfindattr(t, nil, "ip")) == nil){
ndbfree(t);
goto no;
}
strncpy(mx[i].ip, tip->val, sizeof(mx[i].ip)-1);
ndbfree(t);
continue;
no:
/* remove mx[i] and go around again */
nmx--;
mx[i] = mx[nmx];
i--;
}
return nmx;
}
static int
compar(const void *a, const void *b)
{
return ((Mx*)a)->pref - ((Mx*)b)->pref;
}
/* break up an address to its component parts */
void
dial_string_parse(char *str, DS *ds)
{
char *p, *p2;
strncpy(ds->buf, str, sizeof(ds->buf));
ds->buf[sizeof(ds->buf)-1] = 0;
p = strchr(ds->buf, '!');
if(p == 0) {
ds->netdir = 0;
ds->proto = "net";
ds->host = ds->buf;
} else {
if(*ds->buf != '/'){
ds->netdir = 0;
ds->proto = ds->buf;
} else {
for(p2 = p; *p2 != '/'; p2--)
;
*p2++ = 0;
ds->netdir = ds->buf;
ds->proto = p2;
}
*p = 0;
ds->host = p + 1;
}
ds->service = strchr(ds->host, '!');
if(ds->service)
*ds->service++ = 0;
if(*ds->host == '$')
expand_meta(ds);
}
static void
expand_meta(DS *ds)
{
static Ndb *db;
Ndbs s;
char *sys, *smtpserver;
/* can't ask cs, so query database directly. */
sys = sysname();
if(db == nil)
db = ndbopen(0);
smtpserver = ndbgetvalue(db, &s, "sys", sys, "smtp", nil);
snprint(ds->host, 128, "%s", smtpserver);
}
|