1 /* $Cambridge: exim/src/src/mime.c,v 1.15 2006/09/05 15:34:41 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 uschar
*mime_decode_qp_char(uschar
*qp_p
, int *c
) {
45 uschar
*initial_pos
= qp_p
;
47 /* advance one char */
50 /* Check for two hex digits and decode them */
51 if (isxdigit(*qp_p
) && isxdigit(qp_p
[1])) {
52 /* Do hex conversion */
53 if (isdigit(*qp_p
)) {*c
= *qp_p
- '0';}
54 else {*c
= toupper(*qp_p
) - 'A' + 10;};
56 if (isdigit(qp_p
[1])) {*c
|= qp_p
[1] - '0';}
57 else {*c
|= toupper(qp_p
[1]) - 'A' + 10;};
61 /* tab or whitespace may follow just ignore it if it precedes \n */
62 while (*qp_p
== '\t' || *qp_p
== ' ' || *qp_p
== '\r')
66 /* hit soft line break */
71 /* illegal char here */
78 uschar
*mime_parse_line(uschar
*buffer
, uschar
*data
, uschar
*encoding
, int *num_decoded
) {
80 if (encoding
== NULL
) {
81 /* no encoding type at all */
83 memcpy(data
, buffer
, Ustrlen(buffer
));
84 data
[(Ustrlen(buffer
))] = 0;
85 *num_decoded
= Ustrlen(data
);
88 else if (Ustrcmp(encoding
,"base64") == 0) {
92 /* ----- BASE64 ---------------------------------------------------- */
93 /* NULL out '\r' and '\n' chars */
94 while (Ustrrchr(p
,'\r') != NULL
) {
95 *(Ustrrchr(p
,'\r')) = '\0';
97 while (Ustrrchr(p
,'\n') != NULL
) {
98 *(Ustrrchr(p
,'\n')) = '\0';
101 while (*(p
+offset
) != '\0') {
102 /* hit illegal char ? */
103 if (mime_b64
[*(p
+offset
)] == 128) {
104 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64
);
108 *p
= mime_b64
[*(p
+offset
)];
114 /* line is translated, start bit shifting */
120 /* byte 0 ---------------------- */
124 data
[(*num_decoded
)] = *p
;
125 data
[(*num_decoded
)] <<= 2;
128 data
[(*num_decoded
)] |= tmp_c
;
131 /* byte 1 ---------------------- */
135 data
[(*num_decoded
)] = *p
;
136 data
[(*num_decoded
)] <<= 4;
139 data
[(*num_decoded
)] |= tmp_c
;
142 /* byte 2 ---------------------- */
146 data
[(*num_decoded
)] = *p
;
147 data
[(*num_decoded
)] <<= 6;
148 data
[(*num_decoded
)] |= *(p
+1);
154 /* ----------------------------------------------------------------- */
156 else if (Ustrcmp(encoding
,"quoted-printable") == 0) {
159 /* ----- QP -------------------------------------------------------- */
163 int decode_qp_result
;
165 p
= mime_decode_qp_char(p
,&decode_qp_result
);
167 if (decode_qp_result
== -2) {
168 /* Error from decoder. p is unchanged. */
169 mime_set_anomaly(MIME_ANOMALY_BROKEN_QP
);
170 data
[(*num_decoded
)] = '=';
174 else if (decode_qp_result
== -1) {
177 else if (decode_qp_result
>= 0) {
178 data
[(*num_decoded
)] = decode_qp_result
;
183 data
[(*num_decoded
)] = *p
;
189 /* ----------------------------------------------------------------- */
191 /* unknown encoding type, just dump as-is */
192 else goto NO_DECODING
;
196 FILE *mime_get_decode_file(uschar
*pname
, uschar
*fname
) {
200 filename
= (uschar
*)malloc(2048);
202 if ((pname
!= NULL
) && (fname
!= NULL
)) {
203 (void)string_format(filename
, 2048, "%s/%s", pname
, fname
);
204 f
= modefopen(filename
,"wb+",SPOOL_MODE
);
206 else if (pname
== NULL
) {
207 f
= modefopen(fname
,"wb+",SPOOL_MODE
);
209 else if (fname
== NULL
) {
213 /* must find first free sequential filename */
216 (void)string_format(filename
,2048,"%s/%s-%05u", pname
, message_id
, file_nr
);
221 result
= stat(CS filename
,&mystat
);
224 f
= modefopen(filename
,"wb+",SPOOL_MODE
);
227 /* set expansion variable */
228 mime_decoded_filename
= filename
;
234 int mime_decode(uschar
**listptr
) {
236 uschar
*list
= *listptr
;
238 uschar option_buffer
[1024];
239 uschar decode_path
[1024];
240 FILE *decode_file
= NULL
;
241 uschar
*buffer
= NULL
;
242 uschar
*decode_buffer
= NULL
;
244 unsigned int size_counter
= 0;
246 if (mime_stream
== NULL
)
249 f_pos
= ftell(mime_stream
);
251 /* build default decode path (will exist since MBOX must be spooled up) */
252 (void)string_format(decode_path
,1024,"%s/scan/%s",spool_directory
,message_id
);
254 /* reserve a line and decoder buffer to work in */
255 buffer
= (uschar
*)malloc(MIME_MAX_LINE_LENGTH
+1);
256 if (buffer
== NULL
) {
257 log_write(0, LOG_PANIC
,
258 "decode ACL condition: can't allocate %d bytes of memory.", MIME_MAX_LINE_LENGTH
+1);
262 decode_buffer
= (uschar
*)malloc(MIME_MAX_LINE_LENGTH
+1);
263 if (decode_buffer
== NULL
) {
264 log_write(0, LOG_PANIC
,
265 "decode ACL condition: can't allocate %d bytes of memory.", MIME_MAX_LINE_LENGTH
+1);
269 /* try to find 1st option */
270 if ((option
= string_nextinlist(&list
, &sep
,
272 sizeof(option_buffer
))) != NULL
) {
274 /* parse 1st option */
275 if ( (Ustrcmp(option
,"false") == 0) || (Ustrcmp(option
,"0") == 0) ) {
276 /* explicitly no decoding */
280 if (Ustrcmp(option
,"default") == 0) {
281 /* explicit default path + file names */
285 if (option
[0] == '/') {
288 memset(&statbuf
,0,sizeof(statbuf
));
290 /* assume either path or path+file name */
291 if ( (stat(CS option
, &statbuf
) == 0) && S_ISDIR(statbuf
.st_mode
) )
292 /* is directory, use it as decode_path */
293 decode_file
= mime_get_decode_file(option
, NULL
);
295 /* does not exist or is a file, use as full file name */
296 decode_file
= mime_get_decode_file(NULL
, option
);
299 /* assume file name only, use default path */
300 decode_file
= mime_get_decode_file(decode_path
, option
);
303 /* no option? patch default path */
304 DEFAULT_PATH
: decode_file
= mime_get_decode_file(decode_path
, NULL
);
306 if (decode_file
== NULL
)
309 /* read data linewise and dump it to the file,
310 while looking for the current boundary */
311 while(fgets(CS buffer
, MIME_MAX_LINE_LENGTH
, mime_stream
) != NULL
) {
312 uschar
*decoded_line
= NULL
;
313 int decoded_line_length
= 0;
315 if (mime_current_boundary
!= NULL
) {
316 /* boundary line must start with 2 dashes */
317 if (Ustrncmp(buffer
,"--",2) == 0) {
318 if (Ustrncmp((buffer
+2),mime_current_boundary
,Ustrlen(mime_current_boundary
)) == 0)
323 decoded_line
= mime_parse_line(buffer
, decode_buffer
, mime_content_transfer_encoding
, &decoded_line_length
);
325 /* write line to decode file */
326 if (fwrite(decoded_line
, 1, decoded_line_length
, decode_file
) < decoded_line_length
) {
327 /* error/short write */
328 clearerr(mime_stream
);
329 fseek(mime_stream
,f_pos
,SEEK_SET
);
332 size_counter
+= decoded_line_length
;
334 if (size_counter
> 1023) {
335 if ((mime_content_size
+ (size_counter
/ 1024)) < 65535)
336 mime_content_size
+= (size_counter
/ 1024);
338 mime_content_size
= 65535;
339 size_counter
= (size_counter
% 1024);
344 (void)fclose(decode_file
);
346 clearerr(mime_stream
);
347 fseek(mime_stream
,f_pos
,SEEK_SET
);
349 /* round up remaining size bytes to one k */
357 int mime_get_header(FILE *f
, uschar
*header
) {
360 int header_value_mode
= 0;
361 int header_open_brackets
= 0;
369 /* always skip CRs */
370 if (c
== '\r') continue;
373 if (num_copied
> 0) {
374 /* look if next char is '\t' or ' ' */
377 if ( (c
== '\t') || (c
== ' ') ) continue;
380 /* end of the header, terminate with ';' */
385 /* skip control characters */
386 if (c
< 32) continue;
388 if (header_value_mode
) {
389 /* --------- value mode ----------- */
390 /* skip leading whitespace */
391 if ( ((c
== '\t') || (c
== ' ')) && (header_value_mode
== 1) )
394 /* we have hit a non-whitespace char, start copying value data */
395 header_value_mode
= 2;
398 if (c
== '"') continue;
400 /* leave value mode on ';' */
402 header_value_mode
= 0;
404 /* -------------------------------- */
407 /* -------- non-value mode -------- */
408 /* skip whitespace + tabs */
409 if ( (c
== ' ') || (c
== '\t') )
412 /* quote next char. can be used
413 to escape brackets. */
418 header_open_brackets
++;
421 else if ((c
== ')') && header_open_brackets
) {
422 header_open_brackets
--;
425 else if ( (c
== '=') && !header_open_brackets
) {
426 /* enter value mode */
427 header_value_mode
= 1;
430 /* skip chars while we are in a comment */
431 if (header_open_brackets
> 0)
433 /* -------------------------------- */
436 /* copy the char to the buffer */
437 header
[num_copied
] = (uschar
)c
;
441 /* break if header buffer is full */
442 if (num_copied
> MIME_MAX_HEADER_SIZE
-1) {
447 if ((num_copied
> 0) && (header
[num_copied
-1] != ';')) {
448 header
[num_copied
-1] = ';';
452 header
[num_copied
] = '\0';
454 /* return 0 for EOF or empty line */
455 if ((c
== EOF
) || (num_copied
== 1))
462 int mime_acl_check(uschar
*acl
, FILE *f
, struct mime_boundary_context
*context
,
463 uschar
**user_msgptr
, uschar
**log_msgptr
) {
465 uschar
*header
= NULL
;
466 struct mime_boundary_context nested_context
;
468 /* reserve a line buffer to work in */
469 header
= (uschar
*)malloc(MIME_MAX_HEADER_SIZE
+1);
470 if (header
== NULL
) {
471 log_write(0, LOG_PANIC
,
472 "MIME ACL: can't allocate %d bytes of memory.", MIME_MAX_HEADER_SIZE
+1);
476 /* Not actually used at the moment, but will be vital to fixing
477 * some RFC 2046 nonconformance later... */
478 nested_context
.parent
= context
;
480 /* loop through parts */
483 /* reset all per-part mime variables */
484 mime_anomaly_level
= 0;
485 mime_anomaly_text
= NULL
;
486 mime_boundary
= NULL
;
488 mime_decoded_filename
= NULL
;
489 mime_filename
= NULL
;
490 mime_content_description
= NULL
;
491 mime_content_disposition
= NULL
;
492 mime_content_id
= NULL
;
493 mime_content_transfer_encoding
= NULL
;
494 mime_content_type
= NULL
;
495 mime_is_multipart
= 0;
496 mime_content_size
= 0;
499 If boundary is null, we assume that *f is positioned on the start of headers (for example,
500 at the very beginning of a message.
501 If a boundary is given, we must first advance to it to reach the start of the next header
505 /* NOTE -- there's an error here -- RFC2046 specifically says to
506 * check for outer boundaries. This code doesn't do that, and
507 * I haven't fixed this.
509 * (I have moved partway towards adding support, however, by adding
510 * a "parent" field to my new boundary-context structure.)
512 if (context
!= NULL
) {
513 while(fgets(CS header
, MIME_MAX_HEADER_SIZE
, f
) != NULL
) {
514 /* boundary line must start with 2 dashes */
515 if (Ustrncmp(header
,"--",2) == 0) {
516 if (Ustrncmp((header
+2),context
->boundary
,Ustrlen(context
->boundary
)) == 0) {
518 if (Ustrncmp((header
+2+Ustrlen(context
->boundary
)),"--",2) == 0) {
519 /* END boundary found */
520 debug_printf("End boundary found %s\n", context
->boundary
);
524 debug_printf("Next part with boundary %s\n", context
->boundary
);
526 /* can't use break here */
531 /* Hit EOF or read error. Ugh. */
532 debug_printf("Hit EOF ...\n");
537 /* parse headers, set up expansion variables */
538 while(mime_get_header(f
,header
)) {
540 /* loop through header list */
541 for (i
= 0; i
< mime_header_list_size
; i
++) {
542 uschar
*header_value
= NULL
;
543 int header_value_len
= 0;
545 /* found an interesting header? */
546 if (strncmpic(mime_header_list
[i
].name
,header
,mime_header_list
[i
].namelen
) == 0) {
547 uschar
*p
= header
+ mime_header_list
[i
].namelen
;
548 /* yes, grab the value (normalize to lower case)
549 and copy to its corresponding expansion variable */
554 header_value_len
= (p
- (header
+ mime_header_list
[i
].namelen
));
555 header_value
= (uschar
*)malloc(header_value_len
+1);
556 memset(header_value
,0,header_value_len
+1);
557 p
= header
+ mime_header_list
[i
].namelen
;
558 Ustrncpy(header_value
, p
, header_value_len
);
559 debug_printf("Found %s MIME header, value is '%s'\n", mime_header_list
[i
].name
, header_value
);
560 *((uschar
**)(mime_header_list
[i
].value
)) = header_value
;
562 /* make p point to the next character after the closing ';' */
563 p
+= (header_value_len
+1);
565 /* grab all param=value tags on the remaining line, check if they are interesting */
566 NEXT_PARAM_SEARCH
: while (*p
!= 0) {
568 for (j
= 0; j
< mime_parameter_list_size
; j
++) {
569 uschar
*param_value
= NULL
;
570 int param_value_len
= 0;
572 /* found an interesting parameter? */
573 if (strncmpic(mime_parameter_list
[j
].name
,p
,mime_parameter_list
[j
].namelen
) == 0) {
574 uschar
*q
= p
+ mime_parameter_list
[j
].namelen
;
575 /* yes, grab the value and copy to its corresponding expansion variable */
576 while(*q
!= ';') q
++;
577 param_value_len
= (q
- (p
+ mime_parameter_list
[j
].namelen
));
578 param_value
= (uschar
*)malloc(param_value_len
+1);
579 memset(param_value
,0,param_value_len
+1);
580 q
= p
+ mime_parameter_list
[j
].namelen
;
581 Ustrncpy(param_value
, q
, param_value_len
);
582 param_value
= rfc2047_decode(param_value
, check_rfc2047_length
, NULL
, 32, ¶m_value_len
, &q
);
583 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
);
584 *((uschar
**)(mime_parameter_list
[j
].value
)) = param_value
;
585 p
+= (mime_parameter_list
[j
].namelen
+ param_value_len
+ 1);
586 goto NEXT_PARAM_SEARCH
;
589 /* There is something, but not one of our interesting parameters.
590 Advance to the next semicolon */
591 while(*p
!= ';') p
++;
598 /* set additional flag variables (easier access) */
599 if ( (mime_content_type
!= NULL
) &&
600 (Ustrncmp(mime_content_type
,"multipart",9) == 0) )
601 mime_is_multipart
= 1;
603 /* Make a copy of the boundary pointer.
604 Required since mime_boundary is global
605 and can be overwritten further down in recursion */
606 nested_context
.boundary
= mime_boundary
;
608 /* raise global counter */
611 /* copy current file handle to global variable */
613 mime_current_boundary
= context
? context
->boundary
: 0;
615 /* Note the context */
616 mime_is_coverletter
= !(context
&& context
->context
== MBC_ATTACHMENT
);
618 /* call ACL handling function */
619 rc
= acl_check(ACL_WHERE_MIME
, NULL
, acl
, user_msgptr
, log_msgptr
);
622 mime_current_boundary
= NULL
;
626 /* If we have a multipart entity and a boundary, go recursive */
627 if ( (mime_content_type
!= NULL
) &&
628 (nested_context
.boundary
!= NULL
) &&
629 (Ustrncmp(mime_content_type
,"multipart",9) == 0) ) {
630 debug_printf("Entering multipart recursion, boundary '%s'\n", nested_context
.boundary
);
632 if (context
&& context
->context
== MBC_ATTACHMENT
)
633 nested_context
.context
= MBC_ATTACHMENT
;
634 else if (!Ustrcmp(mime_content_type
,"multipart/alternative")
635 || !Ustrcmp(mime_content_type
,"multipart/related"))
636 nested_context
.context
= MBC_COVERLETTER_ALL
;
638 nested_context
.context
= MBC_COVERLETTER_ONESHOT
;
640 rc
= mime_acl_check(acl
, f
, &nested_context
, user_msgptr
, log_msgptr
);
643 else if ( (mime_content_type
!= NULL
) &&
644 (Ustrncmp(mime_content_type
,"message/rfc822",14) == 0) ) {
645 uschar
*rfc822name
= NULL
;
646 uschar filename
[2048];
650 /* must find first free sequential filename */
653 (void)string_format(filename
,2048,"%s/scan/%s/__rfc822_%05u", spool_directory
, message_id
, file_nr
);
658 result
= stat(CS filename
,&mystat
);
662 rfc822name
= filename
;
664 /* decode RFC822 attachment */
665 mime_decoded_filename
= NULL
;
667 mime_current_boundary
= context
? context
->boundary
: NULL
;
668 mime_decode(&rfc822name
);
670 mime_current_boundary
= NULL
;
671 if (mime_decoded_filename
== NULL
) {
672 /* decoding failed */
673 log_write(0, LOG_MAIN
,
674 "mime_regex acl condition warning - could not decode RFC822 MIME part to file.");
677 mime_decoded_filename
= NULL
;
681 /* If the boundary of this instance is NULL, we are finished here */
682 if (context
== NULL
) break;
684 if (context
->context
== MBC_COVERLETTER_ONESHOT
)
685 context
->context
= MBC_ATTACHMENT
;