1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 */
9 #ifdef WITH_CONTENT_SCAN
13 FILE *mime_stream
= NULL
;
14 uschar
*mime_current_boundary
= NULL
;
16 /*************************************************
17 * set MIME anomaly level + text *
18 *************************************************/
20 /* Small wrapper to set the two expandables which
21 give info on detected "problems" in MIME
22 encodings. Those are defined in mime.h. */
24 void mime_set_anomaly(int level
, const char *text
) {
25 mime_anomaly_level
= level
;
26 mime_anomaly_text
= CUS text
;
30 /*************************************************
31 * decode quoted-printable chars *
32 *************************************************/
34 /* gets called when we hit a =
35 returns: new pointer position
38 -1 - soft line break, no char
42 uschar
*mime_decode_qp_char(uschar
*qp_p
, int *c
) {
43 uschar
*initial_pos
= qp_p
;
45 /* advance one char */
48 /* Check for two hex digits and decode them */
49 if (isxdigit(*qp_p
) && isxdigit(qp_p
[1])) {
50 /* Do hex conversion */
51 if (isdigit(*qp_p
)) {*c
= *qp_p
- '0';}
52 else {*c
= toupper(*qp_p
) - 'A' + 10;};
54 if (isdigit(qp_p
[1])) {*c
|= qp_p
[1] - '0';}
55 else {*c
|= toupper(qp_p
[1]) - 'A' + 10;};
59 /* tab or whitespace may follow just ignore it if it precedes \n */
60 while (*qp_p
== '\t' || *qp_p
== ' ' || *qp_p
== '\r')
64 /* hit soft line break */
69 /* illegal char here */
75 /* just dump MIME part without any decoding */
77 mime_decode_asis(FILE* in
, FILE* out
, uschar
* boundary
)
79 ssize_t len
, size
= 0;
80 uschar buffer
[MIME_MAX_LINE_LENGTH
];
82 while(fgets(CS buffer
, MIME_MAX_LINE_LENGTH
, mime_stream
) != NULL
) {
84 && Ustrncmp(buffer
, "--", 2) == 0
85 && Ustrncmp((buffer
+2), boundary
, Ustrlen(boundary
)) == 0
89 len
= Ustrlen(buffer
);
90 if (fwrite(buffer
, 1, (size_t)len
, out
) < len
)
98 /* decode base64 MIME part */
100 mime_decode_base64(FILE* in
, FILE* out
, uschar
* boundary
)
102 uschar ibuf
[MIME_MAX_LINE_LENGTH
], obuf
[MIME_MAX_LINE_LENGTH
];
104 ssize_t len
, size
= 0;
109 while (Ufgets(ibuf
, MIME_MAX_LINE_LENGTH
, in
) != NULL
)
112 && Ustrncmp(ibuf
, "--", 2) == 0
113 && Ustrncmp((ibuf
+2), boundary
, Ustrlen(boundary
)) == 0
117 for (ipos
= ibuf
; *ipos
!= '\r' && *ipos
!= '\n' && *ipos
!= 0; ++ipos
) {
123 /* skip bad characters */
124 if (mime_b64
[*ipos
] == 128) {
125 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
128 /* simple state-machine */
129 switch((bytestate
++) & 3) {
131 *opos
= mime_b64
[*ipos
] << 2;
134 *opos
|= mime_b64
[*ipos
] >> 4;
136 *opos
= mime_b64
[*ipos
] << 4;
139 *opos
|= mime_b64
[*ipos
] >> 2;
141 *opos
= mime_b64
[*ipos
] << 6;
144 *opos
|= mime_b64
[*ipos
];
149 /* something to write? */
152 if (fwrite(obuf
, 1, len
, out
) != len
)
153 return -1; /* error */
155 /* copy incomplete last byte to start of obuf, where we continue */
156 if ((bytestate
& 3) != 0)
162 /* write out last byte if it was incomplete */
164 if (fwrite(obuf
, 1, 1, out
) != 1)
173 /* decode quoted-printable MIME part */
175 mime_decode_qp(FILE* in
, FILE* out
, uschar
* boundary
)
177 uschar ibuf
[MIME_MAX_LINE_LENGTH
], obuf
[MIME_MAX_LINE_LENGTH
];
179 ssize_t len
, size
= 0;
181 while (fgets(CS ibuf
, MIME_MAX_LINE_LENGTH
, in
) != NULL
)
184 && Ustrncmp(ibuf
, "--", 2) == 0
185 && Ustrncmp((ibuf
+2), boundary
, Ustrlen(boundary
)) == 0
187 break; /* todo: check for missing boundary */
194 int decode_qp_result
;
196 ipos
= mime_decode_qp_char(ipos
, &decode_qp_result
);
198 if (decode_qp_result
== -2) {
199 /* Error from decoder. ipos is unchanged. */
200 mime_set_anomaly(MIME_ANOMALY_BROKEN_QP
);
205 else if (decode_qp_result
== -1) {
208 else if (decode_qp_result
>= 0) {
209 *opos
= decode_qp_result
;
219 /* something to write? */
222 if (fwrite(obuf
, 1, len
, out
) != len
)
223 return -1; /* error */
231 FILE *mime_get_decode_file(uschar
*pname
, uschar
*fname
) {
235 filename
= (uschar
*)malloc(2048);
237 if ((pname
!= NULL
) && (fname
!= NULL
)) {
238 (void)string_format(filename
, 2048, "%s/%s", pname
, fname
);
239 f
= modefopen(filename
,"wb+",SPOOL_MODE
);
241 else if (pname
== NULL
) {
242 f
= modefopen(fname
,"wb+",SPOOL_MODE
);
244 else if (fname
== NULL
) {
248 /* must find first free sequential filename */
251 (void)string_format(filename
,2048,"%s/%s-%05u", pname
, message_id
, file_nr
);
256 result
= stat(CS filename
,&mystat
);
259 f
= modefopen(filename
,"wb+",SPOOL_MODE
);
262 /* set expansion variable */
263 mime_decoded_filename
= filename
;
269 int mime_decode(uschar
**listptr
) {
271 uschar
*list
= *listptr
;
273 uschar option_buffer
[1024];
274 uschar decode_path
[1024];
275 FILE *decode_file
= NULL
;
277 ssize_t size_counter
= 0;
278 ssize_t (*decode_function
)(FILE*, FILE*, uschar
*);
280 if (mime_stream
== NULL
)
283 f_pos
= ftell(mime_stream
);
285 /* build default decode path (will exist since MBOX must be spooled up) */
286 (void)string_format(decode_path
,1024,"%s/scan/%s",spool_directory
,message_id
);
288 /* try to find 1st option */
289 if ((option
= string_nextinlist(&list
, &sep
,
291 sizeof(option_buffer
))) != NULL
) {
293 /* parse 1st option */
294 if ( (Ustrcmp(option
,"false") == 0) || (Ustrcmp(option
,"0") == 0) ) {
295 /* explicitly no decoding */
299 if (Ustrcmp(option
,"default") == 0) {
300 /* explicit default path + file names */
304 if (option
[0] == '/') {
307 memset(&statbuf
,0,sizeof(statbuf
));
309 /* assume either path or path+file name */
310 if ( (stat(CS option
, &statbuf
) == 0) && S_ISDIR(statbuf
.st_mode
) )
311 /* is directory, use it as decode_path */
312 decode_file
= mime_get_decode_file(option
, NULL
);
314 /* does not exist or is a file, use as full file name */
315 decode_file
= mime_get_decode_file(NULL
, option
);
318 /* assume file name only, use default path */
319 decode_file
= mime_get_decode_file(decode_path
, option
);
322 /* no option? patch default path */
323 DEFAULT_PATH
: decode_file
= mime_get_decode_file(decode_path
, NULL
);
325 if (decode_file
== NULL
)
328 /* decode according to mime type */
329 if (mime_content_transfer_encoding
== NULL
)
330 /* no encoding, dump as-is */
331 decode_function
= mime_decode_asis
;
332 else if (Ustrcmp(mime_content_transfer_encoding
, "base64") == 0)
333 decode_function
= mime_decode_base64
;
334 else if (Ustrcmp(mime_content_transfer_encoding
, "quoted-printable") == 0)
335 decode_function
= mime_decode_qp
;
337 /* unknown encoding type, just dump as-is */
338 decode_function
= mime_decode_asis
;
340 size_counter
= decode_function(mime_stream
, decode_file
, mime_current_boundary
);
342 clearerr(mime_stream
);
343 fseek(mime_stream
, f_pos
, SEEK_SET
);
345 if (fclose(decode_file
) != 0 || size_counter
< 0)
348 /* round up to the next KiB */
349 mime_content_size
= (size_counter
+ 1023) / 1024;
354 int mime_get_header(FILE *f
, uschar
*header
) {
357 int header_value_mode
= 0;
358 int header_open_brackets
= 0;
366 /* always skip CRs */
367 if (c
== '\r') continue;
370 if (num_copied
> 0) {
371 /* look if next char is '\t' or ' ' */
374 if ( (c
== '\t') || (c
== ' ') ) continue;
377 /* end of the header, terminate with ';' */
382 /* skip control characters */
383 if (c
< 32) continue;
385 if (header_value_mode
) {
386 /* --------- value mode ----------- */
387 /* skip leading whitespace */
388 if ( ((c
== '\t') || (c
== ' ')) && (header_value_mode
== 1) )
391 /* we have hit a non-whitespace char, start copying value data */
392 header_value_mode
= 2;
395 if (c
== '"') continue;
397 /* leave value mode on ';' */
399 header_value_mode
= 0;
401 /* -------------------------------- */
404 /* -------- non-value mode -------- */
405 /* skip whitespace + tabs */
406 if ( (c
== ' ') || (c
== '\t') )
409 /* quote next char. can be used
410 to escape brackets. */
415 header_open_brackets
++;
418 else if ((c
== ')') && header_open_brackets
) {
419 header_open_brackets
--;
422 else if ( (c
== '=') && !header_open_brackets
) {
423 /* enter value mode */
424 header_value_mode
= 1;
427 /* skip chars while we are in a comment */
428 if (header_open_brackets
> 0)
430 /* -------------------------------- */
433 /* copy the char to the buffer */
434 header
[num_copied
] = (uschar
)c
;
438 /* break if header buffer is full */
439 if (num_copied
> MIME_MAX_HEADER_SIZE
-1) {
444 if ((num_copied
> 0) && (header
[num_copied
-1] != ';')) {
445 header
[num_copied
-1] = ';';
449 header
[num_copied
] = '\0';
451 /* return 0 for EOF or empty line */
452 if ((c
== EOF
) || (num_copied
== 1))
459 int mime_acl_check(uschar
*acl
, FILE *f
, struct mime_boundary_context
*context
,
460 uschar
**user_msgptr
, uschar
**log_msgptr
) {
462 uschar
*header
= NULL
;
463 struct mime_boundary_context nested_context
;
465 /* reserve a line buffer to work in */
466 header
= (uschar
*)malloc(MIME_MAX_HEADER_SIZE
+1);
467 if (header
== NULL
) {
468 log_write(0, LOG_PANIC
,
469 "MIME ACL: can't allocate %d bytes of memory.", MIME_MAX_HEADER_SIZE
+1);
473 /* Not actually used at the moment, but will be vital to fixing
474 * some RFC 2046 nonconformance later... */
475 nested_context
.parent
= context
;
477 /* loop through parts */
480 /* reset all per-part mime variables */
481 mime_anomaly_level
= 0;
482 mime_anomaly_text
= NULL
;
483 mime_boundary
= NULL
;
485 mime_decoded_filename
= NULL
;
486 mime_filename
= NULL
;
487 mime_content_description
= NULL
;
488 mime_content_disposition
= NULL
;
489 mime_content_id
= NULL
;
490 mime_content_transfer_encoding
= NULL
;
491 mime_content_type
= NULL
;
492 mime_is_multipart
= 0;
493 mime_content_size
= 0;
496 If boundary is null, we assume that *f is positioned on the start of headers (for example,
497 at the very beginning of a message.
498 If a boundary is given, we must first advance to it to reach the start of the next header
502 /* NOTE -- there's an error here -- RFC2046 specifically says to
503 * check for outer boundaries. This code doesn't do that, and
504 * I haven't fixed this.
506 * (I have moved partway towards adding support, however, by adding
507 * a "parent" field to my new boundary-context structure.)
509 if (context
!= NULL
) {
510 while(fgets(CS header
, MIME_MAX_HEADER_SIZE
, f
) != NULL
) {
511 /* boundary line must start with 2 dashes */
512 if (Ustrncmp(header
,"--",2) == 0) {
513 if (Ustrncmp((header
+2),context
->boundary
,Ustrlen(context
->boundary
)) == 0) {
515 if (Ustrncmp((header
+2+Ustrlen(context
->boundary
)),"--",2) == 0) {
516 /* END boundary found */
517 debug_printf("End boundary found %s\n", context
->boundary
);
521 debug_printf("Next part with boundary %s\n", context
->boundary
);
523 /* can't use break here */
528 /* Hit EOF or read error. Ugh. */
529 debug_printf("Hit EOF ...\n");
534 /* parse headers, set up expansion variables */
535 while(mime_get_header(f
,header
)) {
537 /* loop through header list */
538 for (i
= 0; i
< mime_header_list_size
; i
++) {
539 uschar
*header_value
= NULL
;
540 int header_value_len
= 0;
542 /* found an interesting header? */
543 if (strncmpic(mime_header_list
[i
].name
,header
,mime_header_list
[i
].namelen
) == 0) {
544 uschar
*p
= header
+ mime_header_list
[i
].namelen
;
545 /* yes, grab the value (normalize to lower case)
546 and copy to its corresponding expansion variable */
551 header_value_len
= (p
- (header
+ mime_header_list
[i
].namelen
));
552 header_value
= (uschar
*)malloc(header_value_len
+1);
553 memset(header_value
,0,header_value_len
+1);
554 p
= header
+ mime_header_list
[i
].namelen
;
555 Ustrncpy(header_value
, p
, header_value_len
);
556 debug_printf("Found %s MIME header, value is '%s'\n", mime_header_list
[i
].name
, header_value
);
557 *((uschar
**)(mime_header_list
[i
].value
)) = header_value
;
559 /* make p point to the next character after the closing ';' */
560 p
+= (header_value_len
+1);
562 /* grab all param=value tags on the remaining line, check if they are interesting */
563 NEXT_PARAM_SEARCH
: while (*p
!= 0) {
565 for (j
= 0; j
< mime_parameter_list_size
; j
++) {
566 uschar
*param_value
= NULL
;
567 int param_value_len
= 0;
569 /* found an interesting parameter? */
570 if (strncmpic(mime_parameter_list
[j
].name
,p
,mime_parameter_list
[j
].namelen
) == 0) {
571 uschar
*q
= p
+ mime_parameter_list
[j
].namelen
;
572 /* yes, grab the value and copy to its corresponding expansion variable */
573 while(*q
!= ';') q
++;
574 param_value_len
= (q
- (p
+ mime_parameter_list
[j
].namelen
));
575 param_value
= (uschar
*)malloc(param_value_len
+1);
576 memset(param_value
,0,param_value_len
+1);
577 q
= p
+ mime_parameter_list
[j
].namelen
;
578 Ustrncpy(param_value
, q
, param_value_len
);
579 param_value
= rfc2047_decode(param_value
, check_rfc2047_length
, NULL
, 32, ¶m_value_len
, &q
);
580 debug_printf("Found %s MIME parameter in %s header, value is '%s'\n", mime_parameter_list
[j
].name
, mime_header_list
[i
].name
, param_value
);
581 *((uschar
**)(mime_parameter_list
[j
].value
)) = param_value
;
582 p
+= (mime_parameter_list
[j
].namelen
+ param_value_len
+ 1);
583 goto NEXT_PARAM_SEARCH
;
586 /* There is something, but not one of our interesting parameters.
587 Advance to the next semicolon */
588 while(*p
!= ';') p
++;
595 /* set additional flag variables (easier access) */
596 if ( (mime_content_type
!= NULL
) &&
597 (Ustrncmp(mime_content_type
,"multipart",9) == 0) )
598 mime_is_multipart
= 1;
600 /* Make a copy of the boundary pointer.
601 Required since mime_boundary is global
602 and can be overwritten further down in recursion */
603 nested_context
.boundary
= mime_boundary
;
605 /* raise global counter */
608 /* copy current file handle to global variable */
610 mime_current_boundary
= context
? context
->boundary
: 0;
612 /* Note the context */
613 mime_is_coverletter
= !(context
&& context
->context
== MBC_ATTACHMENT
);
615 /* call ACL handling function */
616 rc
= acl_check(ACL_WHERE_MIME
, NULL
, acl
, user_msgptr
, log_msgptr
);
619 mime_current_boundary
= NULL
;
623 /* If we have a multipart entity and a boundary, go recursive */
624 if ( (mime_content_type
!= NULL
) &&
625 (nested_context
.boundary
!= NULL
) &&
626 (Ustrncmp(mime_content_type
,"multipart",9) == 0) ) {
627 debug_printf("Entering multipart recursion, boundary '%s'\n", nested_context
.boundary
);
629 if (context
&& context
->context
== MBC_ATTACHMENT
)
630 nested_context
.context
= MBC_ATTACHMENT
;
631 else if (!Ustrcmp(mime_content_type
,"multipart/alternative")
632 || !Ustrcmp(mime_content_type
,"multipart/related"))
633 nested_context
.context
= MBC_COVERLETTER_ALL
;
635 nested_context
.context
= MBC_COVERLETTER_ONESHOT
;
637 rc
= mime_acl_check(acl
, f
, &nested_context
, user_msgptr
, log_msgptr
);
640 else if ( (mime_content_type
!= NULL
) &&
641 (Ustrncmp(mime_content_type
,"message/rfc822",14) == 0) ) {
642 uschar
*rfc822name
= NULL
;
643 uschar filename
[2048];
647 /* must find first free sequential filename */
650 (void)string_format(filename
,2048,"%s/scan/%s/__rfc822_%05u", spool_directory
, message_id
, file_nr
);
655 result
= stat(CS filename
,&mystat
);
659 rfc822name
= filename
;
661 /* decode RFC822 attachment */
662 mime_decoded_filename
= NULL
;
664 mime_current_boundary
= context
? context
->boundary
: NULL
;
665 mime_decode(&rfc822name
);
667 mime_current_boundary
= NULL
;
668 if (mime_decoded_filename
== NULL
) {
669 /* decoding failed */
670 log_write(0, LOG_MAIN
,
671 "mime_regex acl condition warning - could not decode RFC822 MIME part to file.");
674 mime_decoded_filename
= NULL
;
678 /* If the boundary of this instance is NULL, we are finished here */
679 if (context
== NULL
) break;
681 if (context
->context
== MBC_COVERLETTER_ONESHOT
)
682 context
->context
= MBC_ATTACHMENT
;