1 /* $Cambridge: exim/src/src/mime.c,v 1.6 2005/03/08 16:57:28 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 */
11 #ifdef WITH_CONTENT_SCAN
15 FILE *mime_stream
= NULL
;
16 uschar
*mime_current_boundary
= NULL
;
18 /*************************************************
19 * set MIME anomaly level + text *
20 *************************************************/
22 /* Small wrapper to set the two expandables which
23 give info on detected "problems" in MIME
24 encodings. Those are defined in mime.h. */
26 void mime_set_anomaly(int level
, char *text
) {
27 mime_anomaly_level
= level
;
28 mime_anomaly_text
= US text
;
32 /*************************************************
33 * decode quoted-printable chars *
34 *************************************************/
36 /* gets called when we hit a =
37 returns: new pointer position
40 -1 - soft line break, no char
44 unsigned int mime_qp_hstr_i(uschar
*cptr
) {
45 unsigned int i
, j
= 0;
46 while (cptr
&& *cptr
&& isxdigit(*cptr
)) {
55 uschar
*mime_decode_qp_char(uschar
*qp_p
,int *c
) {
56 uschar hex
[] = {0,0,0};
58 uschar
*initial_pos
= qp_p
;
60 /* advance one char */
64 if ( (*qp_p
== '\t') || (*qp_p
== ' ') || (*qp_p
== '\r') ) {
65 /* tab or whitespace may follow
66 just ignore it, but remember
67 that this is not a valid hex
73 else if ( (('0' <= *qp_p
) && (*qp_p
<= '9')) || (('A' <= *qp_p
) && (*qp_p
<= 'F')) || (('a' <= *qp_p
) && (*qp_p
<= 'f')) ) {
74 /* this is a valid hex char, if nan is unset */
85 else if (*qp_p
== '\n') {
86 /* hit soft line break already, continue */
91 /* illegal char here */
96 if ( (('0' <= *qp_p
) && (*qp_p
<= '9')) || (('A' <= *qp_p
) && (*qp_p
<= 'F')) || (('a' <= *qp_p
) && (*qp_p
<= 'f')) ) {
99 /* do hex conversion */
100 *c
= mime_qp_hstr_i(hex
);
118 uschar
*mime_parse_line(uschar
*buffer
, uschar
*data
, uschar
*encoding
, int *num_decoded
) {
120 if (encoding
== NULL
) {
121 /* no encoding type at all */
123 memcpy(data
, buffer
, Ustrlen(buffer
));
124 data
[(Ustrlen(buffer
))] = 0;
125 *num_decoded
= Ustrlen(data
);
128 else if (Ustrcmp(encoding
,"base64") == 0) {
132 /* ----- BASE64 ---------------------------------------------------- */
133 /* NULL out '\r' and '\n' chars */
134 while (Ustrrchr(p
,'\r') != NULL
) {
135 *(Ustrrchr(p
,'\r')) = '\0';
137 while (Ustrrchr(p
,'\n') != NULL
) {
138 *(Ustrrchr(p
,'\n')) = '\0';
141 while (*(p
+offset
) != '\0') {
142 /* hit illegal char ? */
143 if (mime_b64
[*(p
+offset
)] == 128) {
144 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
148 *p
= mime_b64
[*(p
+offset
)];
154 /* line is translated, start bit shifting */
160 /* byte 0 ---------------------- */
162 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
165 data
[(*num_decoded
)] = *p
;
166 data
[(*num_decoded
)] <<= 2;
169 data
[(*num_decoded
)] |= tmp_c
;
172 /* byte 1 ---------------------- */
174 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
177 data
[(*num_decoded
)] = *p
;
178 data
[(*num_decoded
)] <<= 4;
181 data
[(*num_decoded
)] |= tmp_c
;
184 /* byte 2 ---------------------- */
186 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
189 data
[(*num_decoded
)] = *p
;
190 data
[(*num_decoded
)] <<= 6;
191 data
[(*num_decoded
)] |= *(p
+1);
197 /* ----------------------------------------------------------------- */
199 else if (Ustrcmp(encoding
,"quoted-printable") == 0) {
202 /* ----- QP -------------------------------------------------------- */
206 int decode_qp_result
;
208 p
= mime_decode_qp_char(p
,&decode_qp_result
);
210 if (decode_qp_result
== -2) {
211 /* Error from decoder. p is unchanged. */
212 mime_set_anomaly(MIME_ANOMALY_BROKEN_QP
);
213 data
[(*num_decoded
)] = '=';
217 else if (decode_qp_result
== -1) {
220 else if (decode_qp_result
>= 0) {
221 data
[(*num_decoded
)] = decode_qp_result
;
226 data
[(*num_decoded
)] = *p
;
232 /* ----------------------------------------------------------------- */
234 /* unknown encoding type, just dump as-is */
235 else goto NO_DECODING
;
239 FILE *mime_get_decode_file(uschar
*pname
, uschar
*fname
) {
243 filename
= (uschar
*)malloc(2048);
245 if ((pname
!= NULL
) && (fname
!= NULL
)) {
246 snprintf(CS filename
, 2048, "%s/%s", pname
, fname
);
247 f
= fopen(CS filename
,"w+");
249 else if (pname
== NULL
) {
250 f
= fopen(CS fname
,"w+");
252 else if (fname
== NULL
) {
256 /* must find first free sequential filename */
259 snprintf(CS filename
,2048,"%s/%s-%05u", pname
, message_id
, file_nr
);
264 result
= stat(CS filename
,&mystat
);
267 f
= fopen(CS filename
,"w+");
270 /* set expansion variable */
271 mime_decoded_filename
= filename
;
277 int mime_decode(uschar
**listptr
) {
279 uschar
*list
= *listptr
;
281 uschar option_buffer
[1024];
282 uschar decode_path
[1024];
283 FILE *decode_file
= NULL
;
284 uschar
*buffer
= NULL
;
285 uschar
*decode_buffer
= NULL
;
287 unsigned int size_counter
= 0;
289 if (mime_stream
== NULL
)
292 f_pos
= ftell(mime_stream
);
294 /* build default decode path (will exist since MBOX must be spooled up) */
295 snprintf(CS decode_path
,1024,"%s/scan/%s",spool_directory
,message_id
);
297 /* reserve a line and decoder buffer to work in */
298 buffer
= (uschar
*)malloc(MIME_MAX_LINE_LENGTH
+1);
299 if (buffer
== NULL
) {
300 log_write(0, LOG_PANIC
,
301 "decode ACL condition: can't allocate %d bytes of memory.", MIME_MAX_LINE_LENGTH
+1);
305 decode_buffer
= (uschar
*)malloc(MIME_MAX_LINE_LENGTH
+1);
306 if (decode_buffer
== NULL
) {
307 log_write(0, LOG_PANIC
,
308 "decode ACL condition: can't allocate %d bytes of memory.", MIME_MAX_LINE_LENGTH
+1);
312 /* try to find 1st option */
313 if ((option
= string_nextinlist(&list
, &sep
,
315 sizeof(option_buffer
))) != NULL
) {
317 /* parse 1st option */
318 if ( (Ustrcmp(option
,"false") == 0) || (Ustrcmp(option
,"0") == 0) ) {
319 /* explicitly no decoding */
323 if (Ustrcmp(option
,"default") == 0) {
324 /* explicit default path + file names */
328 if (option
[0] == '/') {
331 memset(&statbuf
,0,sizeof(statbuf
));
333 /* assume either path or path+file name */
334 if ( (stat(CS option
, &statbuf
) == 0) && S_ISDIR(statbuf
.st_mode
) )
335 /* is directory, use it as decode_path */
336 decode_file
= mime_get_decode_file(option
, NULL
);
338 /* does not exist or is a file, use as full file name */
339 decode_file
= mime_get_decode_file(NULL
, option
);
342 /* assume file name only, use default path */
343 decode_file
= mime_get_decode_file(decode_path
, option
);
346 /* no option? patch default path */
347 DEFAULT_PATH
: decode_file
= mime_get_decode_file(decode_path
, NULL
);
349 if (decode_file
== NULL
)
352 /* read data linewise and dump it to the file,
353 while looking for the current boundary */
354 while(fgets(CS buffer
, MIME_MAX_LINE_LENGTH
, mime_stream
) != NULL
) {
355 uschar
*decoded_line
= NULL
;
356 int decoded_line_length
= 0;
358 if (mime_current_boundary
!= NULL
) {
359 /* boundary line must start with 2 dashes */
360 if (Ustrncmp(buffer
,"--",2) == 0) {
361 if (Ustrncmp((buffer
+2),mime_current_boundary
,Ustrlen(mime_current_boundary
)) == 0)
366 decoded_line
= mime_parse_line(buffer
, decode_buffer
, mime_content_transfer_encoding
, &decoded_line_length
);
368 /* write line to decode file */
369 if (fwrite(decoded_line
, 1, decoded_line_length
, decode_file
) < decoded_line_length
) {
370 /* error/short write */
371 clearerr(mime_stream
);
372 fseek(mime_stream
,f_pos
,SEEK_SET
);
375 size_counter
+= decoded_line_length
;
377 if (size_counter
> 1023) {
378 if ((mime_content_size
+ (size_counter
/ 1024)) < 65535)
379 mime_content_size
+= (size_counter
/ 1024);
381 mime_content_size
= 65535;
382 size_counter
= (size_counter
% 1024);
389 clearerr(mime_stream
);
390 fseek(mime_stream
,f_pos
,SEEK_SET
);
392 /* round up remaining size bytes to one k */
400 int mime_get_header(FILE *f
, uschar
*header
) {
403 int header_value_mode
= 0;
404 int header_open_brackets
= 0;
412 /* always skip CRs */
413 if (c
== '\r') continue;
416 if (num_copied
> 0) {
417 /* look if next char is '\t' or ' ' */
420 if ( (c
== '\t') || (c
== ' ') ) continue;
423 /* end of the header, terminate with ';' */
428 /* skip control characters */
429 if (c
< 32) continue;
431 if (header_value_mode
) {
432 /* --------- value mode ----------- */
433 /* skip leading whitespace */
434 if ( ((c
== '\t') || (c
== ' ')) && (header_value_mode
== 1) )
437 /* we have hit a non-whitespace char, start copying value data */
438 header_value_mode
= 2;
441 if (c
== '"') continue;
443 /* leave value mode on ';' */
445 header_value_mode
= 0;
447 /* -------------------------------- */
450 /* -------- non-value mode -------- */
451 /* skip whitespace + tabs */
452 if ( (c
== ' ') || (c
== '\t') )
455 /* quote next char. can be used
456 to escape brackets. */
461 header_open_brackets
++;
464 else if ((c
== ')') && header_open_brackets
) {
465 header_open_brackets
--;
468 else if ( (c
== '=') && !header_open_brackets
) {
469 /* enter value mode */
470 header_value_mode
= 1;
473 /* skip chars while we are in a comment */
474 if (header_open_brackets
> 0)
476 /* -------------------------------- */
479 /* copy the char to the buffer */
480 header
[num_copied
] = (uschar
)c
;
484 /* break if header buffer is full */
485 if (num_copied
> MIME_MAX_HEADER_SIZE
-1) {
490 if (header
[num_copied
-1] != ';') {
491 header
[num_copied
-1] = ';';
495 header
[num_copied
] = '\0';
497 /* return 0 for EOF or empty line */
498 if ((c
== EOF
) || (num_copied
== 1))
505 int mime_acl_check(FILE *f
, struct mime_boundary_context
*context
, uschar
506 **user_msgptr
, uschar
**log_msgptr
) {
508 uschar
*header
= NULL
;
509 struct mime_boundary_context nested_context
;
511 /* reserve a line buffer to work in */
512 header
= (uschar
*)malloc(MIME_MAX_HEADER_SIZE
+1);
513 if (header
== NULL
) {
514 log_write(0, LOG_PANIC
,
515 "acl_smtp_mime: can't allocate %d bytes of memory.", MIME_MAX_HEADER_SIZE
+1);
519 /* Not actually used at the moment, but will be vital to fixing
520 * some RFC 2046 nonconformance later... */
521 nested_context
.parent
= context
;
523 /* loop through parts */
526 /* reset all per-part mime variables */
527 mime_anomaly_level
= 0;
528 mime_anomaly_text
= NULL
;
529 mime_boundary
= NULL
;
531 mime_decoded_filename
= NULL
;
532 mime_filename
= NULL
;
533 mime_content_description
= NULL
;
534 mime_content_disposition
= NULL
;
535 mime_content_id
= NULL
;
536 mime_content_transfer_encoding
= NULL
;
537 mime_content_type
= NULL
;
538 mime_is_multipart
= 0;
539 mime_content_size
= 0;
542 If boundary is null, we assume that *f is positioned on the start of headers (for example,
543 at the very beginning of a message.
544 If a boundary is given, we must first advance to it to reach the start of the next header
548 /* NOTE -- there's an error here -- RFC2046 specifically says to
549 * check for outer boundaries. This code doesn't do that, and
550 * I haven't fixed this.
552 * (I have moved partway towards adding support, however, by adding
553 * a "parent" field to my new boundary-context structure.)
555 if (context
!= NULL
) {
556 while(fgets(CS header
, MIME_MAX_HEADER_SIZE
, f
) != NULL
) {
557 /* boundary line must start with 2 dashes */
558 if (Ustrncmp(header
,"--",2) == 0) {
559 if (Ustrncmp((header
+2),context
->boundary
,Ustrlen(context
->boundary
)) == 0) {
561 if (Ustrncmp((header
+2+Ustrlen(context
->boundary
)),"--",2) == 0) {
562 /* END boundary found */
563 debug_printf("End boundary found %s\n", context
->boundary
);
567 debug_printf("Next part with boundary %s\n", context
->boundary
);
569 /* can't use break here */
574 /* Hit EOF or read error. Ugh. */
575 debug_printf("Hit EOF ...\n");
580 /* parse headers, set up expansion variables */
581 while(mime_get_header(f
,header
)) {
583 /* loop through header list */
584 for (i
= 0; i
< mime_header_list_size
; i
++) {
585 uschar
*header_value
= NULL
;
586 int header_value_len
= 0;
588 /* found an interesting header? */
589 if (strncmpic(mime_header_list
[i
].name
,header
,mime_header_list
[i
].namelen
) == 0) {
590 uschar
*p
= header
+ mime_header_list
[i
].namelen
;
591 /* yes, grab the value (normalize to lower case)
592 and copy to its corresponding expansion variable */
597 header_value_len
= (p
- (header
+ mime_header_list
[i
].namelen
));
598 header_value
= (uschar
*)malloc(header_value_len
+1);
599 memset(header_value
,0,header_value_len
+1);
600 p
= header
+ mime_header_list
[i
].namelen
;
601 Ustrncpy(header_value
, p
, header_value_len
);
602 debug_printf("Found %s MIME header, value is '%s'\n", mime_header_list
[i
].name
, header_value
);
603 *((uschar
**)(mime_header_list
[i
].value
)) = header_value
;
605 /* make p point to the next character after the closing ';' */
606 p
+= (header_value_len
+1);
608 /* grab all param=value tags on the remaining line, check if they are interesting */
609 NEXT_PARAM_SEARCH
: while (*p
!= 0) {
611 for (j
= 0; j
< mime_parameter_list_size
; j
++) {
612 uschar
*param_value
= NULL
;
613 int param_value_len
= 0;
615 /* found an interesting parameter? */
616 if (strncmpic(mime_parameter_list
[j
].name
,p
,mime_parameter_list
[j
].namelen
) == 0) {
617 uschar
*q
= p
+ mime_parameter_list
[j
].namelen
;
618 /* yes, grab the value and copy to its corresponding expansion variable */
619 while(*q
!= ';') q
++;
620 param_value_len
= (q
- (p
+ mime_parameter_list
[j
].namelen
));
621 param_value
= (uschar
*)malloc(param_value_len
+1);
622 memset(param_value
,0,param_value_len
+1);
623 q
= p
+ mime_parameter_list
[j
].namelen
;
624 Ustrncpy(param_value
, q
, param_value_len
);
625 param_value
= rfc2047_decode(param_value
, TRUE
, NULL
, 32, ¶m_value_len
, &q
);
626 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
);
627 *((uschar
**)(mime_parameter_list
[j
].value
)) = param_value
;
628 p
+= (mime_parameter_list
[j
].namelen
+ param_value_len
+ 1);
629 goto NEXT_PARAM_SEARCH
;
632 /* There is something, but not one of our interesting parameters.
633 Advance to the next semicolon */
634 while(*p
!= ';') p
++;
641 /* set additional flag variables (easier access) */
642 if ( (mime_content_type
!= NULL
) &&
643 (Ustrncmp(mime_content_type
,"multipart",9) == 0) )
644 mime_is_multipart
= 1;
646 /* Make a copy of the boundary pointer.
647 Required since mime_boundary is global
648 and can be overwritten further down in recursion */
649 nested_context
.boundary
= mime_boundary
;
651 /* raise global counter */
654 /* copy current file handle to global variable */
656 mime_current_boundary
= context
? context
->boundary
: 0;
658 /* Note the context */
659 mime_is_coverletter
= !(context
&& context
->context
== MBC_ATTACHMENT
);
661 /* call ACL handling function */
662 rc
= acl_check(ACL_WHERE_MIME
, NULL
, acl_smtp_mime
, user_msgptr
, log_msgptr
);
665 mime_current_boundary
= NULL
;
669 /* If we have a multipart entity and a boundary, go recursive */
670 if ( (mime_content_type
!= NULL
) &&
671 (nested_context
.boundary
!= NULL
) &&
672 (Ustrncmp(mime_content_type
,"multipart",9) == 0) ) {
673 debug_printf("Entering multipart recursion, boundary '%s'\n", nested_context
.boundary
);
675 if (context
&& context
->context
== MBC_ATTACHMENT
)
676 nested_context
.context
= MBC_ATTACHMENT
;
677 else if (!Ustrcmp(mime_content_type
,"multipart/alternative")
678 || !Ustrcmp(mime_content_type
,"multipart/related"))
679 nested_context
.context
= MBC_COVERLETTER_ALL
;
681 nested_context
.context
= MBC_COVERLETTER_ONESHOT
;
683 rc
= mime_acl_check(f
, &nested_context
, user_msgptr
, log_msgptr
);
686 else if ( (mime_content_type
!= NULL
) &&
687 (Ustrncmp(mime_content_type
,"message/rfc822",14) == 0) ) {
688 uschar
*rfc822name
= NULL
;
689 uschar filename
[2048];
693 /* must find first free sequential filename */
696 snprintf(CS filename
,2048,"%s/scan/%s/__rfc822_%05u", spool_directory
, message_id
, file_nr
);
701 result
= stat(CS filename
,&mystat
);
705 rfc822name
= filename
;
707 /* decode RFC822 attachment */
708 mime_decoded_filename
= NULL
;
710 mime_current_boundary
= context
? context
->boundary
: NULL
;
711 mime_decode(&rfc822name
);
713 mime_current_boundary
= NULL
;
714 if (mime_decoded_filename
== NULL
) {
715 /* decoding failed */
716 log_write(0, LOG_MAIN
,
717 "mime_regex acl condition warning - could not decode RFC822 MIME part to file.");
720 mime_decoded_filename
= NULL
;
724 /* If the boundary of this instance is NULL, we are finished here */
725 if (context
== NULL
) break;
727 if (context
->context
== MBC_COVERLETTER_ONESHOT
)
728 context
->context
= MBC_ATTACHMENT
;