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
* decode_path
;
222 FILE *decode_file
= NULL
;
224 ssize_t size_counter
= 0;
225 ssize_t (*decode_function
)(FILE*, FILE*, uschar
*);
227 if (!mime_stream
|| (f_pos
= ftell(mime_stream
)) < 0)
230 /* build default decode path (will exist since MBOX must be spooled up) */
231 decode_path
= string_sprintf("%s/scan/%s", spool_directory
, message_id
);
233 /* try to find 1st option */
234 if ((option
= string_nextinlist(&list
, &sep
, NULL
, 0)))
236 /* parse 1st option */
237 if ((Ustrcmp(option
,"false") == 0) || (Ustrcmp(option
,"0") == 0))
238 /* explicitly no decoding */
241 if (Ustrcmp(option
,"default") == 0)
242 /* explicit default path + file names */
245 if (option
[0] == '/')
249 memset(&statbuf
,0,sizeof(statbuf
));
251 /* assume either path or path+file name */
252 if ( (stat(CS option
, &statbuf
) == 0) && S_ISDIR(statbuf
.st_mode
) )
253 /* is directory, use it as decode_path */
254 decode_file
= mime_get_decode_file(option
, NULL
);
256 /* does not exist or is a file, use as full file name */
257 decode_file
= mime_get_decode_file(NULL
, option
);
260 /* assume file name only, use default path */
261 decode_file
= mime_get_decode_file(decode_path
, option
);
265 /* no option? patch default path */
267 decode_file
= mime_get_decode_file(decode_path
, NULL
);
273 /* decode according to mime type */
275 !mime_content_transfer_encoding
276 ? mime_decode_asis
/* no encoding, dump as-is */
277 : Ustrcmp(mime_content_transfer_encoding
, "base64") == 0
279 : Ustrcmp(mime_content_transfer_encoding
, "quoted-printable") == 0
281 : mime_decode_asis
; /* unknown encoding type, just dump as-is */
283 size_counter
= decode_function(mime_stream
, decode_file
, mime_current_boundary
);
285 clearerr(mime_stream
);
286 if (fseek(mime_stream
, f_pos
, SEEK_SET
))
289 if (fclose(decode_file
) != 0 || size_counter
< 0)
292 /* round up to the next KiB */
293 mime_content_size
= (size_counter
+ 1023) / 1024;
300 mime_get_header(FILE *f
, uschar
*header
)
304 int header_value_mode
= 0;
305 int header_open_brackets
= 0;
310 if ((c
= fgetc(f
)) == EOF
) break;
312 /* always skip CRs */
313 if (c
== '\r') continue;
319 /* look if next char is '\t' or ' ' */
320 if ((c
= fgetc(f
)) == EOF
) break;
321 if ( (c
== '\t') || (c
== ' ') ) continue;
324 /* end of the header, terminate with ';' */
329 /* skip control characters */
330 if (c
< 32) continue;
332 if (header_value_mode
)
334 /* --------- value mode ----------- */
335 /* skip leading whitespace */
336 if ( ((c
== '\t') || (c
== ' ')) && (header_value_mode
== 1) )
339 /* we have hit a non-whitespace char, start copying value data */
340 header_value_mode
= 2;
342 if (c
== '"') /* flip "quoted" mode */
343 header_value_mode
= header_value_mode
==2 ? 3 : 2;
345 /* leave value mode on unquoted ';' */
346 if (header_value_mode
== 2 && c
== ';') {
347 header_value_mode
= 0;
349 /* -------------------------------- */
353 /* -------- non-value mode -------- */
354 /* skip whitespace + tabs */
355 if ( (c
== ' ') || (c
== '\t') )
359 /* quote next char. can be used
360 to escape brackets. */
361 if ((c
= fgetc(f
)) == EOF
) break;
365 header_open_brackets
++;
368 else if ((c
== ')') && header_open_brackets
)
370 header_open_brackets
--;
373 else if ( (c
== '=') && !header_open_brackets
) /* enter value mode */
374 header_value_mode
= 1;
376 /* skip chars while we are in a comment */
377 if (header_open_brackets
> 0)
379 /* -------------------------------- */
382 /* copy the char to the buffer */
383 header
[num_copied
++] = (uschar
)c
;
385 /* break if header buffer is full */
386 if (num_copied
> MIME_MAX_HEADER_SIZE
-1)
390 if ((num_copied
> 0) && (header
[num_copied
-1] != ';'))
391 header
[num_copied
-1] = ';';
394 header
[num_copied
] = '\0';
396 /* return 0 for EOF or empty line */
397 if ((c
== EOF
) || (num_copied
== 1))
405 mime_vars_reset(void)
407 mime_anomaly_level
= 0;
408 mime_anomaly_text
= NULL
;
409 mime_boundary
= NULL
;
411 mime_decoded_filename
= NULL
;
412 mime_filename
= NULL
;
413 mime_content_description
= NULL
;
414 mime_content_disposition
= NULL
;
415 mime_content_id
= NULL
;
416 mime_content_transfer_encoding
= NULL
;
417 mime_content_type
= NULL
;
418 mime_is_multipart
= 0;
419 mime_content_size
= 0;
423 /* Grab a parameter value, dealing with quoting.
426 str Input string. Updated on return to point to terminating ; or NUL
429 Allocated string with parameter value
432 mime_param_val(uschar
** sp
)
436 int size
= 0, ptr
= 0;
438 /* debug_printf_indent(" considering paramval '%s'\n", s); */
440 while (*s
&& *s
!= ';') /* ; terminates */
443 s
++; /* skip opening " */
444 while (*s
&& *s
!= '"') /* " protects ; */
445 val
= string_catn(val
, &size
, &ptr
, s
++, 1);
446 if (*s
) s
++; /* skip closing " */
449 val
= string_catn(val
, &size
, &ptr
, s
++, 1);
450 if (val
) val
[ptr
] = '\0';
456 mime_next_semicolon(uschar
* s
)
458 while (*s
&& *s
!= ';') /* ; terminates */
461 s
++; /* skip opening " */
462 while (*s
&& *s
!= '"') /* " protects ; */
464 if (*s
) s
++; /* skip closing " */
473 rfc2231_to_2047(const uschar
* fname
, const uschar
* charset
, int * len
)
475 int size
= 0, ptr
= 0;
476 uschar
* val
= string_catn(NULL
, &size
, &ptr
, US
"=?", 2);
480 val
= string_cat(val
, &size
, &ptr
, charset
);
481 val
= string_catn(val
, &size
, &ptr
, US
"?Q?", 3);
484 if (c
== '%' && isxdigit(fname
[1]) && isxdigit(fname
[2]))
486 val
= string_catn(val
, &size
, &ptr
, US
"=", 1);
487 val
= string_catn(val
, &size
, &ptr
, ++fname
, 2);
491 val
= string_catn(val
, &size
, &ptr
, fname
++, 1);
493 val
= string_catn(val
, &size
, &ptr
, US
"?=", 2);
494 val
[*len
= ptr
] = '\0';
500 mime_acl_check(uschar
*acl
, FILE *f
, struct mime_boundary_context
*context
,
501 uschar
**user_msgptr
, uschar
**log_msgptr
)
504 uschar
* header
= NULL
;
505 struct mime_boundary_context nested_context
;
507 /* reserve a line buffer to work in */
508 header
= store_get(MIME_MAX_HEADER_SIZE
+1);
510 /* Not actually used at the moment, but will be vital to fixing
511 * some RFC 2046 nonconformance later... */
512 nested_context
.parent
= context
;
514 /* loop through parts */
517 /* reset all per-part mime variables */
520 /* If boundary is null, we assume that *f is positioned on the start of
521 headers (for example, at the very beginning of a message. If a boundary is
522 given, we must first advance to it to reach the start of the next header
525 /* NOTE -- there's an error here -- RFC2046 specifically says to
526 * check for outer boundaries. This code doesn't do that, and
527 * I haven't fixed this.
529 * (I have moved partway towards adding support, however, by adding
530 * a "parent" field to my new boundary-context structure.)
532 if (context
) for (;;)
534 if (!fgets(CS header
, MIME_MAX_HEADER_SIZE
, f
))
536 /* Hit EOF or read error. Ugh. */
537 DEBUG(D_acl
) debug_printf_indent("MIME: Hit EOF ...\n");
541 /* boundary line must start with 2 dashes */
542 if ( Ustrncmp(header
, "--", 2) == 0
543 && Ustrncmp(header
+2, context
->boundary
, Ustrlen(context
->boundary
)) == 0
545 { /* found boundary */
546 if (Ustrncmp((header
+2+Ustrlen(context
->boundary
)), "--", 2) == 0)
548 /* END boundary found */
549 DEBUG(D_acl
) debug_printf_indent("MIME: End boundary found %s\n",
554 DEBUG(D_acl
) debug_printf_indent("MIME: Next part with boundary %s\n",
560 /* parse headers, set up expansion variables */
561 while (mime_get_header(f
, header
))
563 struct mime_header
* mh
;
565 /* look for interesting headers */
566 for (mh
= mime_header_list
;
567 mh
< mime_header_list
+ mime_header_list_size
;
568 mh
++) if (strncmpic(mh
->name
, header
, mh
->namelen
) == 0)
570 uschar
* p
= header
+ mh
->namelen
;
573 /* grab the value (normalize to lower case)
574 and copy to its corresponding expansion variable */
576 for (q
= p
; *q
!= ';' && *q
; q
++) ;
577 *mh
->value
= string_copynlc(p
, q
-p
);
578 DEBUG(D_acl
) debug_printf_indent("MIME: found %s header, value is '%s'\n",
579 mh
->name
, *mh
->value
);
581 if (*(p
= q
)) p
++; /* jump past the ; */
584 uschar
* mime_fname
= NULL
;
585 uschar
* mime_fname_rfc2231
= NULL
;
586 uschar
* mime_filename_charset
= NULL
;
587 BOOL decoding_failed
= FALSE
;
589 /* grab all param=value tags on the remaining line,
590 check if they are interesting */
596 DEBUG(D_acl
) debug_printf_indent("MIME: considering paramlist '%s'\n", p
);
599 && strncmpic(CUS
"content-disposition:", header
, 20) == 0
600 && strncmpic(CUS
"filename*", p
, 9) == 0
602 { /* RFC 2231 filename */
605 /* find value of the filename */
607 while(*p
!= '=' && *p
) p
++;
608 if (*p
) p
++; /* p is filename or NUL */
609 q
= mime_param_val(&p
); /* p now trailing ; or NUL */
613 uschar
* temp_string
, * err_msg
;
616 /* build up an un-decoded filename over successive
617 filename*= parameters (for use when 2047 decode fails) */
619 mime_fname_rfc2231
= string_sprintf("%#s%s",
620 mime_fname_rfc2231
, q
);
622 if (!decoding_failed
)
625 if (!mime_filename_charset
)
629 /* look for a ' in the "filename" */
630 while(*s
!= '\'' && *s
) s
++; /* s is 1st ' or NUL */
632 if ((size
= s
-q
) > 0)
633 mime_filename_charset
= string_copyn(q
, size
);
636 while(*p
== '\'') p
++; /* p is after 2nd ' */
641 DEBUG(D_acl
) debug_printf_indent("MIME: charset %s fname '%s'\n",
642 mime_filename_charset
? mime_filename_charset
: US
"<NULL>", p
);
644 temp_string
= rfc2231_to_2047(p
, mime_filename_charset
, &slen
);
645 DEBUG(D_acl
) debug_printf_indent("MIME: 2047-name %s\n", temp_string
);
647 temp_string
= rfc2047_decode(temp_string
, FALSE
, NULL
, ' ',
649 DEBUG(D_acl
) debug_printf_indent("MIME: plain-name %s\n", temp_string
);
651 size
= Ustrlen(temp_string
);
654 decoding_failed
= TRUE
;
656 /* build up a decoded filename over successive
657 filename*= parameters */
659 mime_filename
= mime_fname
= mime_fname
660 ? string_sprintf("%s%s", mime_fname
, temp_string
)
667 /* look for interesting parameters */
668 for (mp
= mime_parameter_list
;
669 mp
< mime_parameter_list
+ nelem(mime_parameter_list
);
671 ) if (strncmpic(mp
->name
, p
, mp
->namelen
) == 0)
674 uschar
* dummy_errstr
;
676 /* grab the value and copy to its expansion variable */
678 q
= mime_param_val(&p
); /* p now trailing ; or NUL */
681 ? rfc2047_decode(q
, check_rfc2047_length
, NULL
, 32, NULL
,
684 DEBUG(D_acl
) debug_printf_indent(
685 "MIME: found %s parameter in %s header, value '%s'\n",
686 mp
->name
, mh
->name
, *mp
->value
);
688 break; /* done matching param names */
692 /* There is something, but not one of our interesting parameters.
693 Advance past the next semicolon */
694 p
= mime_next_semicolon(p
);
696 } /* param scan on line */
698 if (strncmpic(CUS
"content-disposition:", header
, 20) == 0)
700 if (decoding_failed
) mime_filename
= mime_fname_rfc2231
;
702 DEBUG(D_acl
) debug_printf_indent(
703 "MIME: found %s parameter in %s header, value is '%s'\n",
704 "filename", mh
->name
, mime_filename
);
710 /* set additional flag variables (easier access) */
711 if ( mime_content_type
712 && Ustrncmp(mime_content_type
,"multipart",9) == 0
714 mime_is_multipart
= 1;
716 /* Make a copy of the boundary pointer.
717 Required since mime_boundary is global
718 and can be overwritten further down in recursion */
719 nested_context
.boundary
= mime_boundary
;
721 /* raise global counter */
724 /* copy current file handle to global variable */
726 mime_current_boundary
= context
? context
->boundary
: 0;
728 /* Note the context */
729 mime_is_coverletter
= !(context
&& context
->context
== MBC_ATTACHMENT
);
731 /* call ACL handling function */
732 rc
= acl_check(ACL_WHERE_MIME
, NULL
, acl
, user_msgptr
, log_msgptr
);
735 mime_current_boundary
= NULL
;
739 /* If we have a multipart entity and a boundary, go recursive */
740 if ( (mime_content_type
!= NULL
) &&
741 (nested_context
.boundary
!= NULL
) &&
742 (Ustrncmp(mime_content_type
,"multipart",9) == 0) )
745 debug_printf_indent("MIME: Entering multipart recursion, boundary '%s'\n",
746 nested_context
.boundary
);
748 nested_context
.context
=
749 context
&& context
->context
== MBC_ATTACHMENT
751 : Ustrcmp(mime_content_type
,"multipart/alternative") == 0
752 || Ustrcmp(mime_content_type
,"multipart/related") == 0
753 ? MBC_COVERLETTER_ALL
754 : MBC_COVERLETTER_ONESHOT
;
756 rc
= mime_acl_check(acl
, f
, &nested_context
, user_msgptr
, log_msgptr
);
759 else if ( (mime_content_type
!= NULL
) &&
760 (Ustrncmp(mime_content_type
,"message/rfc822",14) == 0) )
762 const uschar
*rfc822name
= NULL
;
763 uschar filename
[2048];
767 /* must find first free sequential filename */
771 (void)string_format(filename
, 2048,
772 "%s/scan/%s/__rfc822_%05u", spool_directory
, message_id
, file_nr
++);
776 result
= stat(CS filename
,&mystat
);
777 } while (result
!= -1);
779 rfc822name
= filename
;
781 /* decode RFC822 attachment */
782 mime_decoded_filename
= NULL
;
784 mime_current_boundary
= context
? context
->boundary
: NULL
;
785 mime_decode(&rfc822name
);
787 mime_current_boundary
= NULL
;
788 if (!mime_decoded_filename
) /* decoding failed */
790 log_write(0, LOG_MAIN
,
791 "MIME acl condition warning - could not decode RFC822 MIME part to file.");
795 mime_decoded_filename
= NULL
;
799 /* If the boundary of this instance is NULL, we are finished here */
802 if (context
->context
== MBC_COVERLETTER_ONESHOT
)
803 context
->context
= MBC_ATTACHMENT
;
811 #endif /*WITH_CONTENT_SCAN*/