Commit | Line | Data |
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8d769cc9 | 1 | /* -*-c-*- |
2 | * | |
9a4b2474 | 3 | * $Id: qmail-checkspam.c,v 1.2 2004/04/08 01:36:26 mdw Exp $ |
8d769cc9 | 4 | * |
5 | * Filter messages for spam | |
6 | * | |
7 | * (c) 2003 Mark Wooding | |
8 | */ | |
9 | ||
841e5aca | 10 | /*----- Licensing notice --------------------------------------------------* |
8d769cc9 | 11 | * |
12 | * This program is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
841e5aca | 16 | * |
8d769cc9 | 17 | * This program is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
841e5aca | 21 | * |
8d769cc9 | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with this program; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
8d769cc9 | 27 | /*----- Header files ------------------------------------------------------*/ |
28 | ||
29 | #include <ctype.h> | |
30 | #include <errno.h> | |
913eb210 | 31 | #include <limits.h> |
8d769cc9 | 32 | #include <stdio.h> |
33 | #include <stdlib.h> | |
34 | #include <string.h> | |
35 | ||
36 | #include <sys/types.h> | |
37 | #include <sys/unistd.h> | |
38 | ||
7bba3c9c MW |
39 | #include <syslog.h> |
40 | ||
8d769cc9 | 41 | #include <libspamc.h> |
42 | ||
43 | /*----- Main code ---------------------------------------------------------*/ | |
44 | ||
45 | static const char *strenv(const char *e, const char *d) | |
46 | { | |
47 | const char *p = getenv(e); | |
48 | if (!p) return (d); | |
49 | return (p); | |
50 | } | |
51 | ||
52 | static double dblenv(const char *e, double d) | |
53 | { | |
54 | const char *p = getenv(e); | |
55 | char *q; | |
56 | int err = errno; | |
57 | double f; | |
58 | if (!p) return (d); | |
59 | errno = 0; | |
60 | f = strtod(p, &q); | |
7bba3c9c MW |
61 | if (errno) { |
62 | syslog(LOG_ERR, "bad floating value `%s' for %s'; ignoring", p, e); | |
63 | return (d); | |
64 | } | |
8d769cc9 | 65 | errno = err; |
66 | return (f); | |
67 | } | |
68 | ||
69 | static int intenv(const char *e, int d) | |
70 | { | |
71 | const char *p = getenv(e); | |
72 | char *q; | |
73 | int err = errno; | |
74 | long l; | |
75 | if (!p) return (d); | |
76 | errno = 0; | |
77 | l = strtol(p, &q, 0); | |
78 | if (errno) return (d); | |
79 | errno = err; | |
7bba3c9c MW |
80 | if (l < 0 || l > INT_MAX) { |
81 | syslog(LOG_ERR, "bad integer value `%s' for `%s'; ignoring", p, e); | |
82 | return (d); | |
83 | } | |
8d769cc9 | 84 | return ((int)l); |
85 | } | |
86 | ||
7bba3c9c MW |
87 | static int safewrite(int fd, const void *p, size_t sz) |
88 | { | |
89 | const char *pp = p; | |
90 | ssize_t n; | |
91 | ||
92 | while (sz > 0) { | |
93 | n = write(fd, pp, sz); | |
94 | if (sz <= 0 && errno != EINTR && errno != EAGAIN) | |
95 | return (-1); | |
96 | sz -= n; | |
97 | pp += n; | |
98 | } | |
99 | return (0); | |
100 | } | |
101 | ||
102 | static int shovel(int from, int to, const char *what) | |
8d769cc9 | 103 | { |
104 | char buf[4096]; | |
105 | ssize_t n; | |
8d769cc9 | 106 | |
107 | for (;;) { | |
108 | n = read(from, buf, sizeof(buf)); | |
7bba3c9c MW |
109 | if (n < 0 && errno != EINTR && errno != EAGAIN) { |
110 | syslog(LOG_ERR, "failed to read %s: %m", what); | |
8d769cc9 | 111 | return (-1); |
7bba3c9c | 112 | } |
8d769cc9 | 113 | else if (!n) |
114 | return (0); | |
7bba3c9c MW |
115 | if (safewrite(to, buf, n) < 0) { |
116 | syslog(LOG_ERR, "failed to write %s: %m", what); | |
117 | return (-1); | |
118 | } | |
119 | } | |
120 | } | |
121 | ||
122 | #define ENVBUF 4096 | |
123 | #define NRCPT 16 | |
124 | struct envelope { | |
125 | unsigned f; | |
126 | #define EF_TRUNC 1u | |
127 | char buf[ENVBUF + 1]; | |
128 | size_t n; | |
129 | const char *send; | |
130 | const char *rcpt[NRCPT]; | |
131 | size_t nrcpt; | |
132 | }; | |
133 | ||
134 | static int readenv(struct envelope *e) | |
135 | { | |
136 | ssize_t n; | |
137 | const char *p, *l; | |
138 | ||
139 | /* Read the raw envelope data. */ | |
140 | e->n = 0; | |
141 | e->f = 0; | |
142 | while (e->n < ENVBUF) { | |
143 | n = read(1, e->buf + e->n, ENVBUF - e->n); | |
144 | if (n < 0 && errno != EINTR && errno != EAGAIN) { | |
145 | syslog(LOG_ERR, "failed to read envelope: %m"); | |
146 | return (-1); | |
8d769cc9 | 147 | } |
7bba3c9c MW |
148 | if (!n) break; |
149 | e->n += n; | |
150 | } | |
151 | e->buf[e->n] = 0; | |
152 | ||
153 | /* Parse up the envelope data. */ | |
154 | p = e->buf; l = p + e->n; | |
155 | e->nrcpt = 0; | |
156 | if (*p++ != 'F') { | |
157 | e->send = "<invalid>"; | |
158 | syslog(LOG_ERR, "corrupt envelope (no sender marker)"); | |
159 | return (-1); | |
160 | } | |
161 | e->send = p; | |
162 | for (;;) { | |
163 | if (p >= l) goto trunc; | |
164 | else if (!*p++) break; | |
8d769cc9 | 165 | } |
7bba3c9c MW |
166 | |
167 | for (;;) { | |
168 | if (p >= l) goto trunc; | |
169 | if (!*p) break; | |
170 | else if (*p++ != 'T') { | |
171 | syslog(LOG_ERR, "corrupt envelope (no recipient marker)"); | |
172 | return (-1); | |
173 | } | |
174 | if (p >= l) goto trunc; | |
175 | if (e->nrcpt < NRCPT) e->rcpt[e->nrcpt++] = p; | |
176 | for (;;) { | |
177 | if (p >= l) goto trunc; | |
178 | else if (!*p++) break; | |
179 | } | |
180 | } | |
181 | return (0); | |
182 | ||
183 | /* Failed to reach the final terminator; maybe there's more. This isn't a | |
184 | * very bad situation. | |
185 | */ | |
186 | trunc: | |
187 | e->f |= EF_TRUNC; | |
188 | return (0); | |
189 | } | |
190 | ||
191 | static void real(void) | |
192 | { | |
193 | const char *qmq = | |
194 | strenv("QMAIL_CHECKSPAM_QUEUE", "/var/qmail/bin/qmail-queue"); | |
195 | execlp(qmq, qmq, (char *)0); | |
196 | syslog(LOG_ERR, "failed to exec %s: %m", qmq); | |
197 | exit(56); | |
198 | } | |
199 | ||
200 | static int split(int *fd_m, int *fd_e) | |
201 | { | |
202 | pid_t kid; | |
203 | int pm[2], pe[2]; | |
204 | ||
205 | if (pipe(pm) || pipe(pe)) return (-1); | |
206 | if ((kid = fork()) < 0) return (-1); | |
207 | if (kid) { | |
208 | dup2(pm[0], 0); close(pm[0]); close(pm[1]); | |
209 | dup2(pe[0], 1); close(pe[0]); close(pe[1]); | |
210 | real(); | |
211 | } else { | |
212 | close(pm[0]); *fd_m = pm[1]; | |
213 | close(pe[0]); *fd_e = pe[1]; | |
214 | } | |
215 | return (0); | |
216 | } | |
217 | ||
218 | static int writemsg(struct message *m, int fd_m, int shovelp) | |
219 | { | |
220 | if (message_write(fd_m, m) < 0) { | |
221 | syslog(LOG_ERR, "failed to write message body: %m"); | |
222 | return (-1); | |
223 | } | |
224 | if (shovelp && shovel(0, fd_m, "message body")) | |
225 | return (-1); | |
226 | close(fd_m); | |
227 | return (0); | |
228 | } | |
229 | ||
230 | static int writeenv(struct envelope *e, int fd_e) | |
231 | { | |
232 | if (safewrite(fd_e, e->buf, e->n) < 0) { | |
233 | syslog(LOG_ERR, "failed to write envelope: %m"); | |
234 | return (-1); | |
235 | } | |
236 | if ((e->f & EF_TRUNC) && shovel(1, fd_e, "envelope")) | |
237 | return (-1); | |
238 | close(fd_e); | |
239 | return (0); | |
240 | } | |
241 | ||
242 | static void logenv(struct envelope *e) | |
243 | { | |
244 | size_t i; | |
245 | ||
246 | syslog(LOG_NOTICE, "sender = %s", e->send); | |
247 | for (i = 0; i < e->nrcpt; i++) | |
248 | syslog(LOG_NOTICE, "recipient %lu = %s", (unsigned long)i, e->rcpt[i]); | |
8d769cc9 | 249 | } |
250 | ||
251 | int main(int argc, char *argv[]) | |
252 | { | |
253 | struct sockaddr sa; | |
254 | struct message m; | |
7bba3c9c MW |
255 | struct envelope e; |
256 | int fd_m, fd_e; | |
257 | const char *p; | |
258 | double thresh; | |
259 | int rc, port; | |
260 | ||
261 | /* Set up logging output. */ | |
262 | if ((p = strrchr(argv[0], '/')) == 0) p = argv[0]; else p++; | |
263 | openlog(p, LOG_PID, LOG_MAIL); | |
8d769cc9 | 264 | |
7bba3c9c MW |
265 | /* Read configuration from the environment. */ |
266 | if (getenv("RELAYCLIENT")) real(); | |
8d769cc9 | 267 | m.max_len = intenv("QMAIL_CHECKSPAM_MAXLEN", 2 * 1024 * 1024); |
268 | m.timeout = intenv("QMAIL_CHECKSPAM_TIMEOUT", 300); | |
7bba3c9c MW |
269 | |
270 | /* Slurp an initial chunk of the message. */ | |
8d769cc9 | 271 | rc = message_read(0, 0, &m); |
7bba3c9c MW |
272 | |
273 | switch (rc) { | |
274 | ||
275 | case 0: | |
276 | /* We read the message body OK. Now try to slurp in the envelope and | |
277 | * write a useful message. | |
278 | */ | |
279 | if (readenv(&e)) return (54); | |
280 | syslog(LOG_NOTICE, "scanning message"); | |
281 | logenv(&e); | |
282 | ||
283 | /* Filter the message and see what happens. */ | |
284 | p = strenv("QMAIL_CHECKSPAM_SPAMDHOST", "localhost"); | |
285 | port = intenv("QMAIL_CHECKSPAM_SPAMDPORT", 783); | |
286 | if (lookup_host(p, port, &sa)) { | |
287 | syslog(LOG_ERR, "lookup failed for host `%s', port %d", p, port); | |
288 | return (56); | |
289 | } | |
290 | if (message_filter(&sa, "spamd", 0, &m)) { | |
291 | syslog(LOG_ERR, "filter failed unexpectedly"); | |
292 | return (74); | |
293 | } | |
294 | ||
295 | /* Check the resulting score. */ | |
296 | thresh = dblenv("QMAIL_CHECKSPAM_THRESH", m.threshold); | |
297 | if (m.score >= thresh) { | |
298 | syslog(LOG_NOTICE, "rejecting: score %g >= %g", m.score, thresh); | |
299 | return (31); | |
300 | } | |
301 | syslog(LOG_NOTICE, "accepting: score %g < %g", m.score, thresh); | |
302 | ||
303 | /* Send the remaining stuff on to the real server. */ | |
304 | if (split(&fd_m, &fd_e)) return (56); | |
305 | if (writemsg(&m, fd_m, 0) || writeenv(&e, fd_e)) _exit(127); | |
306 | break; | |
307 | ||
308 | case EX_TOOBIG: | |
309 | /* Message was too big. We must pass it all on to the real server | |
310 | * before picking up the envelope. | |
311 | */ | |
312 | syslog(LOG_NOTICE, "message too large for filtering"); | |
313 | if (split(&fd_m, &fd_e)) return (56); | |
314 | if (writemsg(&m, fd_m, 1) || readenv(&e)) _exit(127); | |
315 | logenv(&e); | |
316 | if (writeenv(&e, fd_e)) _exit(127); | |
317 | break; | |
318 | ||
319 | default: | |
320 | syslog(LOG_ERR, "failed to read message (rc = %d): %m", rc); | |
321 | return (54); | |
8d769cc9 | 322 | } |
323 | ||
7bba3c9c | 324 | return (0); |
8d769cc9 | 325 | } |
326 | ||
327 | /*----- That's all, folks -------------------------------------------------*/ |