1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004, 2015
7 * Copyright (c) The Exim Maintainers 2016
11 #ifdef WITH_CONTENT_SCAN /* entire file */
15 FILE *mime_stream
= NULL
;
16 uschar
*mime_current_boundary
= NULL
;
18 static mime_header mime_header_list
[] = {
19 { US
"content-type:", 13, &mime_content_type
},
20 { US
"content-disposition:", 20, &mime_content_disposition
},
21 { US
"content-transfer-encoding:", 26, &mime_content_transfer_encoding
},
22 { US
"content-id:", 11, &mime_content_id
},
23 { US
"content-description:", 20, &mime_content_description
}
26 static int mime_header_list_size
= nelem(mime_header_list
);
28 static mime_parameter mime_parameter_list
[] = {
29 { US
"name=", 5, &mime_filename
},
30 { US
"filename=", 9, &mime_filename
},
31 { US
"charset=", 8, &mime_charset
},
32 { US
"boundary=", 9, &mime_boundary
}
36 /*************************************************
37 * set MIME anomaly level + text *
38 *************************************************/
40 /* Small wrapper to set the two expandables which
41 give info on detected "problems" in MIME
42 encodings. Indexes are defined in mime.h. */
45 mime_set_anomaly(int idx
)
50 } anom
[] = { {1, CUS
"Broken Quoted-Printable encoding detected"},
51 {2, CUS
"Broken BASE64 encoding detected"} };
53 mime_anomaly_level
= anom
[idx
].level
;
54 mime_anomaly_text
= anom
[idx
].text
;
58 /*************************************************
59 * decode quoted-printable chars *
60 *************************************************/
62 /* gets called when we hit a =
63 returns: new pointer position
66 -1 - soft line break, no char
71 mime_decode_qp_char(uschar
*qp_p
, int *c
)
73 uschar
*initial_pos
= qp_p
;
75 /* advance one char */
78 /* Check for two hex digits and decode them */
79 if (isxdigit(*qp_p
) && isxdigit(qp_p
[1]))
81 /* Do hex conversion */
82 *c
= (isdigit(*qp_p
) ? *qp_p
- '0' : toupper(*qp_p
) - 'A' + 10) <<4;
84 *c
|= isdigit(*qp_p
) ? *qp_p
- '0' : toupper(*qp_p
) - 'A' + 10;
88 /* tab or whitespace may follow just ignore it if it precedes \n */
89 while (*qp_p
== '\t' || *qp_p
== ' ' || *qp_p
== '\r')
92 if (*qp_p
== '\n') /* hit soft line break */
98 /* illegal char here */
104 /* just dump MIME part without any decoding */
106 mime_decode_asis(FILE* in
, FILE* out
, uschar
* boundary
)
108 ssize_t len
, size
= 0;
109 uschar buffer
[MIME_MAX_LINE_LENGTH
];
111 while(fgets(CS buffer
, MIME_MAX_LINE_LENGTH
, mime_stream
) != NULL
)
114 && Ustrncmp(buffer
, "--", 2) == 0
115 && Ustrncmp((buffer
+2), boundary
, Ustrlen(boundary
)) == 0
119 len
= Ustrlen(buffer
);
120 if (fwrite(buffer
, 1, (size_t)len
, out
) < len
)
129 /* decode quoted-printable MIME part */
131 mime_decode_qp(FILE* in
, FILE* out
, uschar
* boundary
)
133 uschar ibuf
[MIME_MAX_LINE_LENGTH
], obuf
[MIME_MAX_LINE_LENGTH
];
135 ssize_t len
, size
= 0;
137 while (fgets(CS ibuf
, MIME_MAX_LINE_LENGTH
, in
) != NULL
)
140 && Ustrncmp(ibuf
, "--", 2) == 0
141 && Ustrncmp((ibuf
+2), boundary
, Ustrlen(boundary
)) == 0
143 break; /* todo: check for missing boundary */
152 int decode_qp_result
;
154 ipos
= mime_decode_qp_char(ipos
, &decode_qp_result
);
156 if (decode_qp_result
== -2)
158 /* Error from decoder. ipos is unchanged. */
159 mime_set_anomaly(MIME_ANOMALY_BROKEN_QP
);
163 else if (decode_qp_result
== -1)
165 else if (decode_qp_result
>= 0)
166 *opos
++ = decode_qp_result
;
171 /* something to write? */
175 if (fwrite(obuf
, 1, len
, out
) != len
) return -1; /* error */
184 * Return open filehandle for combo of path and file.
185 * Side-effect: set mime_decoded_filename, to copy in allocated mem
188 mime_get_decode_file(uschar
*pname
, uschar
*fname
)
191 mime_decoded_filename
= string_sprintf("%s/%s", pname
, fname
);
193 mime_decoded_filename
= string_copy(fname
);
199 /* must find first free sequential filename */
203 mime_decoded_filename
= string_sprintf("%s/%s-%05u", pname
, message_id
, file_nr
++);
207 result
= stat(CS mime_decoded_filename
, &mystat
);
208 } while(result
!= -1);
211 return modefopen(mime_decoded_filename
, "wb+", SPOOL_MODE
);
216 mime_decode(const uschar
**listptr
)
219 const uschar
*list
= *listptr
;
221 uschar option_buffer
[1024];
222 uschar decode_path
[1024];
223 FILE *decode_file
= NULL
;
225 ssize_t size_counter
= 0;
226 ssize_t (*decode_function
)(FILE*, FILE*, uschar
*);
228 if (!mime_stream
|| (f_pos
= ftell(mime_stream
)) < 0)
231 /* build default decode path (will exist since MBOX must be spooled up) */
232 (void)string_format(decode_path
,1024,"%s/scan/%s",spool_directory
,message_id
);
234 /* try to find 1st option */
235 if ((option
= string_nextinlist(&list
, &sep
,
237 sizeof(option_buffer
))) != NULL
)
239 /* parse 1st option */
240 if ((Ustrcmp(option
,"false") == 0) || (Ustrcmp(option
,"0") == 0))
241 /* explicitly no decoding */
244 if (Ustrcmp(option
,"default") == 0)
245 /* explicit default path + file names */
248 if (option
[0] == '/')
252 memset(&statbuf
,0,sizeof(statbuf
));
254 /* assume either path or path+file name */
255 if ( (stat(CS option
, &statbuf
) == 0) && S_ISDIR(statbuf
.st_mode
) )
256 /* is directory, use it as decode_path */
257 decode_file
= mime_get_decode_file(option
, NULL
);
259 /* does not exist or is a file, use as full file name */
260 decode_file
= mime_get_decode_file(NULL
, option
);
263 /* assume file name only, use default path */
264 decode_file
= mime_get_decode_file(decode_path
, option
);
268 /* no option? patch default path */
270 decode_file
= mime_get_decode_file(decode_path
, NULL
);
276 /* decode according to mime type */
278 !mime_content_transfer_encoding
279 ? mime_decode_asis
/* no encoding, dump as-is */
280 : Ustrcmp(mime_content_transfer_encoding
, "base64") == 0
282 : Ustrcmp(mime_content_transfer_encoding
, "quoted-printable") == 0
284 : mime_decode_asis
; /* unknown encoding type, just dump as-is */
286 size_counter
= decode_function(mime_stream
, decode_file
, mime_current_boundary
);
288 clearerr(mime_stream
);
289 if (fseek(mime_stream
, f_pos
, SEEK_SET
))
292 if (fclose(decode_file
) != 0 || size_counter
< 0)
295 /* round up to the next KiB */
296 mime_content_size
= (size_counter
+ 1023) / 1024;
303 mime_get_header(FILE *f
, uschar
*header
)
307 int header_value_mode
= 0;
308 int header_open_brackets
= 0;
313 if ((c
= fgetc(f
)) == EOF
) break;
315 /* always skip CRs */
316 if (c
== '\r') continue;
322 /* look if next char is '\t' or ' ' */
323 if ((c
= fgetc(f
)) == EOF
) break;
324 if ( (c
== '\t') || (c
== ' ') ) continue;
327 /* end of the header, terminate with ';' */
332 /* skip control characters */
333 if (c
< 32) continue;
335 if (header_value_mode
)
337 /* --------- value mode ----------- */
338 /* skip leading whitespace */
339 if ( ((c
== '\t') || (c
== ' ')) && (header_value_mode
== 1) )
342 /* we have hit a non-whitespace char, start copying value data */
343 header_value_mode
= 2;
345 if (c
== '"') /* flip "quoted" mode */
346 header_value_mode
= header_value_mode
==2 ? 3 : 2;
348 /* leave value mode on unquoted ';' */
349 if (header_value_mode
== 2 && c
== ';') {
350 header_value_mode
= 0;
352 /* -------------------------------- */
356 /* -------- non-value mode -------- */
357 /* skip whitespace + tabs */
358 if ( (c
== ' ') || (c
== '\t') )
362 /* quote next char. can be used
363 to escape brackets. */
364 if ((c
= fgetc(f
)) == EOF
) break;
368 header_open_brackets
++;
371 else if ((c
== ')') && header_open_brackets
)
373 header_open_brackets
--;
376 else if ( (c
== '=') && !header_open_brackets
) /* enter value mode */
377 header_value_mode
= 1;
379 /* skip chars while we are in a comment */
380 if (header_open_brackets
> 0)
382 /* -------------------------------- */
385 /* copy the char to the buffer */
386 header
[num_copied
++] = (uschar
)c
;
388 /* break if header buffer is full */
389 if (num_copied
> MIME_MAX_HEADER_SIZE
-1)
393 if ((num_copied
> 0) && (header
[num_copied
-1] != ';'))
394 header
[num_copied
-1] = ';';
397 header
[num_copied
] = '\0';
399 /* return 0 for EOF or empty line */
400 if ((c
== EOF
) || (num_copied
== 1))
408 mime_vars_reset(void)
410 mime_anomaly_level
= 0;
411 mime_anomaly_text
= NULL
;
412 mime_boundary
= NULL
;
414 mime_decoded_filename
= NULL
;
415 mime_filename
= NULL
;
416 mime_content_description
= NULL
;
417 mime_content_disposition
= NULL
;
418 mime_content_id
= NULL
;
419 mime_content_transfer_encoding
= NULL
;
420 mime_content_type
= NULL
;
421 mime_is_multipart
= 0;
422 mime_content_size
= 0;
426 /* Grab a parameter value, dealing with quoting.
429 str Input string. Updated on return to point to terminating ; or NUL
432 Allocated string with parameter value
435 mime_param_val(uschar
** sp
)
439 int size
= 0, ptr
= 0;
441 /* debug_printf_indent(" considering paramval '%s'\n", s); */
443 while (*s
&& *s
!= ';') /* ; terminates */
446 s
++; /* skip opening " */
447 while (*s
&& *s
!= '"') /* " protects ; */
448 val
= string_catn(val
, &size
, &ptr
, s
++, 1);
449 if (*s
) s
++; /* skip closing " */
452 val
= string_catn(val
, &size
, &ptr
, s
++, 1);
453 if (val
) val
[ptr
] = '\0';
459 mime_next_semicolon(uschar
* s
)
461 while (*s
&& *s
!= ';') /* ; terminates */
464 s
++; /* skip opening " */
465 while (*s
&& *s
!= '"') /* " protects ; */
467 if (*s
) s
++; /* skip closing " */
476 rfc2231_to_2047(const uschar
* fname
, const uschar
* charset
, int * len
)
478 int size
= 0, ptr
= 0;
479 uschar
* val
= string_catn(NULL
, &size
, &ptr
, US
"=?", 2);
483 val
= string_cat(val
, &size
, &ptr
, charset
);
484 val
= string_catn(val
, &size
, &ptr
, US
"?Q?", 3);
487 if (c
== '%' && isxdigit(fname
[1]) && isxdigit(fname
[2]))
489 val
= string_catn(val
, &size
, &ptr
, US
"=", 1);
490 val
= string_catn(val
, &size
, &ptr
, ++fname
, 2);
494 val
= string_catn(val
, &size
, &ptr
, fname
++, 1);
496 val
= string_catn(val
, &size
, &ptr
, US
"?=", 2);
497 val
[*len
= ptr
] = '\0';
503 mime_acl_check(uschar
*acl
, FILE *f
, struct mime_boundary_context
*context
,
504 uschar
**user_msgptr
, uschar
**log_msgptr
)
507 uschar
* header
= NULL
;
508 struct mime_boundary_context nested_context
;
510 /* reserve a line buffer to work in */
511 header
= store_get(MIME_MAX_HEADER_SIZE
+1);
513 /* Not actually used at the moment, but will be vital to fixing
514 * some RFC 2046 nonconformance later... */
515 nested_context
.parent
= context
;
517 /* loop through parts */
520 /* reset all per-part mime variables */
523 /* If boundary is null, we assume that *f is positioned on the start of
524 headers (for example, at the very beginning of a message. If a boundary is
525 given, we must first advance to it to reach the start of the next header
528 /* NOTE -- there's an error here -- RFC2046 specifically says to
529 * check for outer boundaries. This code doesn't do that, and
530 * I haven't fixed this.
532 * (I have moved partway towards adding support, however, by adding
533 * a "parent" field to my new boundary-context structure.)
535 if (context
) for (;;)
537 if (!fgets(CS header
, MIME_MAX_HEADER_SIZE
, f
))
539 /* Hit EOF or read error. Ugh. */
540 DEBUG(D_acl
) debug_printf_indent("MIME: Hit EOF ...\n");
544 /* boundary line must start with 2 dashes */
545 if ( Ustrncmp(header
, "--", 2) == 0
546 && Ustrncmp(header
+2, context
->boundary
, Ustrlen(context
->boundary
)) == 0
548 { /* found boundary */
549 if (Ustrncmp((header
+2+Ustrlen(context
->boundary
)), "--", 2) == 0)
551 /* END boundary found */
552 DEBUG(D_acl
) debug_printf_indent("MIME: End boundary found %s\n",
557 DEBUG(D_acl
) debug_printf_indent("MIME: Next part with boundary %s\n",
563 /* parse headers, set up expansion variables */
564 while (mime_get_header(f
, header
))
566 struct mime_header
* mh
;
568 /* look for interesting headers */
569 for (mh
= mime_header_list
;
570 mh
< mime_header_list
+ mime_header_list_size
;
571 mh
++) if (strncmpic(mh
->name
, header
, mh
->namelen
) == 0)
573 uschar
* p
= header
+ mh
->namelen
;
576 /* grab the value (normalize to lower case)
577 and copy to its corresponding expansion variable */
579 for (q
= p
; *q
!= ';' && *q
; q
++) ;
580 *mh
->value
= string_copynlc(p
, q
-p
);
581 DEBUG(D_acl
) debug_printf_indent("MIME: found %s header, value is '%s'\n",
582 mh
->name
, *mh
->value
);
584 if (*(p
= q
)) p
++; /* jump past the ; */
587 uschar
* mime_fname
= NULL
;
588 uschar
* mime_fname_rfc2231
= NULL
;
589 uschar
* mime_filename_charset
= NULL
;
590 BOOL decoding_failed
= FALSE
;
592 /* grab all param=value tags on the remaining line,
593 check if they are interesting */
599 DEBUG(D_acl
) debug_printf_indent("MIME: considering paramlist '%s'\n", p
);
602 && strncmpic(CUS
"content-disposition:", header
, 20) == 0
603 && strncmpic(CUS
"filename*", p
, 9) == 0
605 { /* RFC 2231 filename */
608 /* find value of the filename */
610 while(*p
!= '=' && *p
) p
++;
611 if (*p
) p
++; /* p is filename or NUL */
612 q
= mime_param_val(&p
); /* p now trailing ; or NUL */
616 uschar
* temp_string
, * err_msg
;
619 /* build up an un-decoded filename over successive
620 filename*= parameters (for use when 2047 decode fails) */
622 mime_fname_rfc2231
= string_sprintf("%#s%s",
623 mime_fname_rfc2231
, q
);
625 if (!decoding_failed
)
628 if (!mime_filename_charset
)
632 /* look for a ' in the "filename" */
633 while(*s
!= '\'' && *s
) s
++; /* s is 1st ' or NUL */
635 if ((size
= s
-q
) > 0)
636 mime_filename_charset
= string_copyn(q
, size
);
639 while(*p
== '\'') p
++; /* p is after 2nd ' */
644 DEBUG(D_acl
) debug_printf_indent("MIME: charset %s fname '%s'\n",
645 mime_filename_charset
? mime_filename_charset
: US
"<NULL>", p
);
647 temp_string
= rfc2231_to_2047(p
, mime_filename_charset
, &slen
);
648 DEBUG(D_acl
) debug_printf_indent("MIME: 2047-name %s\n", temp_string
);
650 temp_string
= rfc2047_decode(temp_string
, FALSE
, NULL
, ' ',
652 DEBUG(D_acl
) debug_printf_indent("MIME: plain-name %s\n", temp_string
);
654 size
= Ustrlen(temp_string
);
657 decoding_failed
= TRUE
;
659 /* build up a decoded filename over successive
660 filename*= parameters */
662 mime_filename
= mime_fname
= mime_fname
663 ? string_sprintf("%s%s", mime_fname
, temp_string
)
670 /* look for interesting parameters */
671 for (mp
= mime_parameter_list
;
672 mp
< mime_parameter_list
+ nelem(mime_parameter_list
);
674 ) if (strncmpic(mp
->name
, p
, mp
->namelen
) == 0)
677 uschar
* dummy_errstr
;
679 /* grab the value and copy to its expansion variable */
681 q
= mime_param_val(&p
); /* p now trailing ; or NUL */
684 ? rfc2047_decode(q
, check_rfc2047_length
, NULL
, 32, NULL
,
687 DEBUG(D_acl
) debug_printf_indent(
688 "MIME: found %s parameter in %s header, value '%s'\n",
689 mp
->name
, mh
->name
, *mp
->value
);
691 break; /* done matching param names */
695 /* There is something, but not one of our interesting parameters.
696 Advance past the next semicolon */
697 p
= mime_next_semicolon(p
);
699 } /* param scan on line */
701 if (strncmpic(CUS
"content-disposition:", header
, 20) == 0)
703 if (decoding_failed
) mime_filename
= mime_fname_rfc2231
;
705 DEBUG(D_acl
) debug_printf_indent(
706 "MIME: found %s parameter in %s header, value is '%s'\n",
707 "filename", mh
->name
, mime_filename
);
713 /* set additional flag variables (easier access) */
714 if ( mime_content_type
715 && Ustrncmp(mime_content_type
,"multipart",9) == 0
717 mime_is_multipart
= 1;
719 /* Make a copy of the boundary pointer.
720 Required since mime_boundary is global
721 and can be overwritten further down in recursion */
722 nested_context
.boundary
= mime_boundary
;
724 /* raise global counter */
727 /* copy current file handle to global variable */
729 mime_current_boundary
= context
? context
->boundary
: 0;
731 /* Note the context */
732 mime_is_coverletter
= !(context
&& context
->context
== MBC_ATTACHMENT
);
734 /* call ACL handling function */
735 rc
= acl_check(ACL_WHERE_MIME
, NULL
, acl
, user_msgptr
, log_msgptr
);
738 mime_current_boundary
= NULL
;
742 /* If we have a multipart entity and a boundary, go recursive */
743 if ( (mime_content_type
!= NULL
) &&
744 (nested_context
.boundary
!= NULL
) &&
745 (Ustrncmp(mime_content_type
,"multipart",9) == 0) )
748 debug_printf_indent("MIME: Entering multipart recursion, boundary '%s'\n",
749 nested_context
.boundary
);
751 nested_context
.context
=
752 context
&& context
->context
== MBC_ATTACHMENT
754 : Ustrcmp(mime_content_type
,"multipart/alternative") == 0
755 || Ustrcmp(mime_content_type
,"multipart/related") == 0
756 ? MBC_COVERLETTER_ALL
757 : MBC_COVERLETTER_ONESHOT
;
759 rc
= mime_acl_check(acl
, f
, &nested_context
, user_msgptr
, log_msgptr
);
762 else if ( (mime_content_type
!= NULL
) &&
763 (Ustrncmp(mime_content_type
,"message/rfc822",14) == 0) )
765 const uschar
*rfc822name
= NULL
;
766 uschar filename
[2048];
770 /* must find first free sequential filename */
774 (void)string_format(filename
, 2048,
775 "%s/scan/%s/__rfc822_%05u", spool_directory
, message_id
, file_nr
++);
779 result
= stat(CS filename
,&mystat
);
780 } while (result
!= -1);
782 rfc822name
= filename
;
784 /* decode RFC822 attachment */
785 mime_decoded_filename
= NULL
;
787 mime_current_boundary
= context
? context
->boundary
: NULL
;
788 mime_decode(&rfc822name
);
790 mime_current_boundary
= NULL
;
791 if (!mime_decoded_filename
) /* decoding failed */
793 log_write(0, LOG_MAIN
,
794 "MIME acl condition warning - could not decode RFC822 MIME part to file.");
798 mime_decoded_filename
= NULL
;
802 /* If the boundary of this instance is NULL, we are finished here */
805 if (context
->context
== MBC_COVERLETTER_ONESHOT
)
806 context
->context
= MBC_ATTACHMENT
;
814 #endif /*WITH_CONTENT_SCAN*/