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Ignore non-base64 junk when decoding MIME

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* src/fns.c (Fbase64_decode_region): Add optional argument
IGNORE-INVALID and pass down to base64_decode_1.
(Fbase64_decode_string): Likewise.
(base64_decode_1): Add argument IGNORE_INVALID.
* doc/lispref/text.texi (Base 64): Document them.
* lisp/gnus/mm-bodies.el (mm-decode-content-transfer-encoding):
Ignore any junk when decoding base64.
This commit is contained in:
Andreas Schwab 2022-10-25 18:22:21 +02:00
parent e5cb66c046
commit 33647b6d63
3 changed files with 34 additions and 38 deletions
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8
doc/lispref/text.texi
View file

@ -4876,7 +4876,7 @@ If the optional argument @var{no-pad} is non-@code{nil} then this
function doesn't generate the padding.
@end defun
@deffn Command base64-decode-region beg end &optional base64url
@deffn Command base64-decode-region beg end &optional base64url ignore-invalid
This function converts the region from @var{beg} to @var{end} from base
64 code into the corresponding decoded text. It returns the length of
the decoded text.
@ -4885,9 +4885,11 @@ The decoding functions ignore newline characters in the encoded text.
If optional argument @var{base64url} is non-@code{nil}, then padding
is optional, and the URL variant of base 64 encoding is used.
If optional argument @var{ignore-invalid} is non-@code{nil}, then any
unrecognized characters are ignored.
@end deffn
@defun base64-decode-string string &optional base64url
@defun base64-decode-string string &optional base64url ignore-invalid
This function converts the string @var{string} from base 64 code into
the corresponding decoded text. It returns a unibyte string containing the
decoded text.
@ -4897,6 +4899,8 @@ The decoding functions ignore newline characters in the encoded text.
If optional argument @var{base64url} is non-@code{nil}, then padding
is optional, and the URL variant of base 64 encoding is used.
If optional argument @var{ignore-invalid} is non-@code{nil}, then any
unrecognized characters are ignored.
@end defun
@node Checksum/Hash

20
lisp/gnus/mm-bodies.el
View file

@ -189,24 +189,8 @@ If TYPE is `text/plain' CRLF->LF translation may occur."
(quoted-printable-decode-region (point-min) (point-max))
t)
((eq encoding 'base64)
(base64-decode-region
(point-min)
(save-excursion
;; Some mailers insert whitespace junk at the end which
;; base64-decode-region dislikes.
(goto-char (point-min))
(while (re-search-forward "^[\t ]*\r?\n" nil t)
(delete-region (match-beginning 0) (match-end 0)))
;; Also ignore junk which could have been added by
;; mailing list software by finding the final line with
;; base64 text.
(goto-char (point-max))
(beginning-of-line)
(while (and (not (mm-base64-line-p))
(not (bobp)))
(forward-line -1))
(forward-line 1)
(point))))
;; MIME says to ignore any non-base64 junk
(base64-decode-region (point-min) (point-max) nil t))
((memq encoding '(nil 7bit 8bit binary))
;; Do nothing.
t)

44
src/fns.c
View file

@ -3661,7 +3661,7 @@ static signed char const base64_char_to_value[2][UCHAR_MAX] =
static ptrdiff_t base64_encode_1 (const char *, char *, ptrdiff_t, bool, bool,
bool, bool);
static ptrdiff_t base64_decode_1 (const char *, char *, ptrdiff_t, bool,
bool, ptrdiff_t *);
bool, bool, ptrdiff_t *);
static Lisp_Object base64_encode_region_1 (Lisp_Object, Lisp_Object, bool,
bool, bool);
@ -3924,7 +3924,7 @@ base64_encode_1 (const char *from, char *to, ptrdiff_t length,
DEFUN ("base64-decode-region", Fbase64_decode_region, Sbase64_decode_region,
2, 3, "r",
2, 4, "r",
doc: /* Base64-decode the region between BEG and END.
Return the length of the decoded data.
@ -3935,8 +3935,11 @@ system.
If the region can't be decoded, signal an error and don't modify the buffer.
Optional third argument BASE64URL determines whether to use the URL variant
of the base 64 encoding, as defined in RFC 4648. */)
(Lisp_Object beg, Lisp_Object end, Lisp_Object base64url)
of the base 64 encoding, as defined in RFC 4648.
If optional fourth argument INGORE-INVALID is non-nil invalid characters
are ignored instead of signaling an error. */)
(Lisp_Object beg, Lisp_Object end, Lisp_Object base64url,
Lisp_Object ignore_invalid)
{
ptrdiff_t ibeg, iend, length, allength;
char *decoded;
@ -3962,7 +3965,8 @@ of the base 64 encoding, as defined in RFC 4648. */)
move_gap_both (XFIXNAT (beg), ibeg);
decoded_length = base64_decode_1 ((char *) BYTE_POS_ADDR (ibeg),
decoded, length, !NILP (base64url),
multibyte, &inserted_chars);
multibyte, !NILP (ignore_invalid),
&inserted_chars);
if (decoded_length > allength)
emacs_abort ();
@ -3995,11 +3999,13 @@ of the base 64 encoding, as defined in RFC 4648. */)
}
DEFUN ("base64-decode-string", Fbase64_decode_string, Sbase64_decode_string,
1, 2, 0,
1, 3, 0,
doc: /* Base64-decode STRING and return the result as a string.
Optional argument BASE64URL determines whether to use the URL variant of
the base 64 encoding, as defined in RFC 4648. */)
(Lisp_Object string, Lisp_Object base64url)
the base 64 encoding, as defined in RFC 4648.
If optional third argument IGNORE-INVALID is non-nil invalid characters are
ignored instead of signaling an error. */)
(Lisp_Object string, Lisp_Object base64url, Lisp_Object ignore_invalid)
{
char *decoded;
ptrdiff_t length, decoded_length;
@ -4015,7 +4021,8 @@ the base 64 encoding, as defined in RFC 4648. */)
/* The decoded result should be unibyte. */
ptrdiff_t decoded_chars;
decoded_length = base64_decode_1 (SSDATA (string), decoded, length,
!NILP (base64url), 0, &decoded_chars);
!NILP (base64url), false,
!NILP (ignore_invalid), &decoded_chars);
if (decoded_length > length)
emacs_abort ();
else if (decoded_length >= 0)
@ -4032,12 +4039,13 @@ the base 64 encoding, as defined in RFC 4648. */)
/* Base64-decode the data at FROM of LENGTH bytes into TO. If
MULTIBYTE, the decoded result should be in multibyte
form. Store the number of produced characters in *NCHARS_RETURN. */
form. If IGNORE_INVALID, ignore invalid base64 characters.
Store the number of produced characters in *NCHARS_RETURN. */
static ptrdiff_t
base64_decode_1 (const char *from, char *to, ptrdiff_t length,
bool base64url,
bool multibyte, ptrdiff_t *nchars_return)
bool base64url, bool multibyte, bool ignore_invalid,
ptrdiff_t *nchars_return)
{
char const *f = from;
char const *flim = from + length;
@ -4063,7 +4071,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
c = *f++;
v1 = b64_char_to_value[c];
}
while (v1 < 0);
while (v1 < 0 || (v1 == 0 && ignore_invalid));
if (v1 == 0)
return -1;
@ -4078,7 +4086,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
c = *f++;
v1 = b64_char_to_value[c];
}
while (v1 < 0);
while (v1 < 0 || (v1 == 0 && ignore_invalid));
if (v1 == 0)
return -1;
@ -4097,7 +4105,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
{
if (f == flim)
{
if (!base64url)
if (!base64url && !ignore_invalid)
return -1;
*nchars_return = nchars;
return e - to;
@ -4105,7 +4113,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
c = *f++;
v1 = b64_char_to_value[c];
}
while (v1 < 0);
while (v1 < 0 || (v1 == 0 && ignore_invalid));
if (c == '=')
{
@ -4139,7 +4147,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
{
if (f == flim)
{
if (!base64url)
if (!base64url && !ignore_invalid)
return -1;
*nchars_return = nchars;
return e - to;
@ -4147,7 +4155,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
c = *f++;
v1 = b64_char_to_value[c];
}
while (v1 < 0);
while (v1 < 0 || (v1 == 0 && ignore_invalid));
if (c == '=')
continue;