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Decode base64/quoted-printable a block at a time #62

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174 changes: 174 additions & 0 deletions mailparse_encoding.c
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Original file line number Diff line number Diff line change
Expand Up @@ -490,6 +490,180 @@ int mb_convert_filter_flush(mb_convert_filter *filter)
return 0;
}

/* =============================================================================
* Bulk (buffer-at-a-time) decoders
*
* These decode a whole input block in one tight loop, appending decoded bytes
* straight to the output smart_string. They reuse the filter's status/cache as
* the carry state between blocks, so the result is byte-for-byte identical to
* feeding the same bytes through mb_convert_filter_feed() one at a time -- but
* without a function-pointer call per input and per output byte, which is the
* dominant cost when decoding large base64/quoted-printable bodies. Only the
* decode directions used during MIME extraction are handled.
* ============================================================================= */

static void mb_base64_decode_block(mb_convert_filter *filter, const char *in, size_t len, smart_string *out)
{
int status = filter->status;
int cache = filter->cache;
size_t i;

for (i = 0; i < len; i++) {
int c = (unsigned char) in[i];
int n;

if (c == 0x0d || c == 0x0a || c == 0x20 || c == 0x09 || c == 0x3d) {
continue; /* CR, LF, SPACE, HTAB or '=' */
}
if (c >= 0x41 && c <= 0x5a) { /* A - Z */
n = c - 65;
} else if (c >= 0x61 && c <= 0x7a) { /* a - z */
n = c - 71;
} else if (c >= 0x30 && c <= 0x39) { /* 0 - 9 */
n = c + 4;
} else if (c == 0x2b) { /* '+' */
n = 62;
} else if (c == 0x2f) { /* '/' */
n = 63;
} else {
continue; /* invalid character, ignored */
}
n &= 0x3f;

switch (status) {
case 0:
status = 1;
cache = n << 18;
break;
case 1:
status = 2;
cache |= n << 12;
break;
case 2:
status = 3;
cache |= n << 6;
break;
default:
status = 0;
n |= cache;
smart_string_appendc(out, (n >> 16) & 0xff);
smart_string_appendc(out, (n >> 8) & 0xff);
smart_string_appendc(out, n & 0xff);
break;
}
}

filter->status = status;
filter->cache = cache;
}

static void mb_base64_flush_block(mb_convert_filter *filter, smart_string *out)
{
int status = filter->status;
int cache = filter->cache;

filter->status = 0;
filter->cache = 0;

if (status >= 2) {
smart_string_appendc(out, (cache >> 16) & 0xff);
if (status >= 3) {
smart_string_appendc(out, (cache >> 8) & 0xff);
}
}
}

static void mb_qprint_decode_block(mb_convert_filter *filter, const char *in, size_t len, smart_string *out)
{
int status = filter->status;
int cache = filter->cache;
size_t i;

for (i = 0; i < len; i++) {
int c = (unsigned char) in[i];
int n, m;

switch (status) {
case 1:
if (hex2code_map[c] >= 0) {
cache = c;
status = 2;
} else if (c == 0x0d) { /* soft line feed */
status = 3;
} else if (c == 0x0a) { /* soft line feed */
status = 0;
} else {
smart_string_appendc(out, 0x3d); /* '=' */
smart_string_appendc(out, c);
status = 0;
}
break;
case 2:
m = hex2code_map[c];
if (m < 0) {
smart_string_appendc(out, 0x3d); /* '=' */
smart_string_appendc(out, cache);
n = c;
} else {
n = hex2code_map[cache] << 4 | m;
}
smart_string_appendc(out, n);
status = 0;
break;
case 3:
if (c != 0x0a) { /* LF */
smart_string_appendc(out, c);
}
status = 0;
break;
default:
if (c == 0x3d) { /* '=' */
status = 1;
} else {
smart_string_appendc(out, c);
}
break;
}
}

filter->status = status;
filter->cache = cache;
}

static void mb_qprint_flush_block(mb_convert_filter *filter, smart_string *out)
{
int status = filter->status;
int cache = filter->cache;

filter->status = 0;
filter->cache = 0;

if (status == 1) {
smart_string_appendc(out, 0x3d); /* '=' */
} else if (status == 2) {
smart_string_appendc(out, 0x3d); /* '=' */
smart_string_appendc(out, cache);
}
}

void mb_convert_filter_feed_block(mb_convert_filter *filter, const char *in, size_t len, smart_string *out)
{
if (filter->from->no_encoding == mb_no_encoding_base64) {
mb_base64_decode_block(filter, in, len, out);
} else if (filter->from->no_encoding == mb_no_encoding_qprint) {
mb_qprint_decode_block(filter, in, len, out);
}
}

void mb_convert_filter_flush_block(mb_convert_filter *filter, smart_string *out)
{
if (filter->from->no_encoding == mb_no_encoding_base64) {
mb_base64_flush_block(filter, out);
} else if (filter->from->no_encoding == mb_no_encoding_qprint) {
mb_qprint_flush_block(filter, out);
}
}

/* =============================================================================
* Encoding lookup functions
* ============================================================================= */
Expand Down
8 changes: 8 additions & 0 deletions mailparse_encoding.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#define MAILPARSE_ENCODING_H

#include "php.h"
#include "Zend/zend_smart_string.h"

/* Encoding identifiers */
enum mb_no_encoding {
Expand Down Expand Up @@ -92,6 +93,13 @@ void mb_convert_filter_delete(mb_convert_filter *filter);
int mb_convert_filter_feed(int c, mb_convert_filter *filter);
int mb_convert_filter_flush(mb_convert_filter *filter);

/* Buffer-at-a-time decoders (BASE64 / Quoted-Printable -> 8bit). They use the
* filter's status/cache as carry state between blocks, so the output is
* identical to feeding the bytes through mb_convert_filter_feed() one at a
* time, without a per-byte function-pointer dispatch. */
void mb_convert_filter_feed_block(mb_convert_filter *filter, const char *in, size_t len, smart_string *out);
void mb_convert_filter_flush_block(mb_convert_filter *filter, smart_string *out);

const mb_encoding* mb_name2encoding(const char *name);
const mb_encoding* mb_no2encoding(enum mb_no_encoding no_encoding);

Expand Down
32 changes: 7 additions & 25 deletions php_mailparse_mime.c
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -906,21 +906,6 @@ PHP_MAILPARSE_API php_mimepart *php_mimepart_find_child_by_position(php_mimepart
return NULL;
}

static int filter_into_work_buffer(int c, void *dat)
{
php_mimepart *part = dat;

smart_string_appendc(&part->parsedata.workbuf, c);

if (part->parsedata.workbuf.len >= 4096) {

part->extract_func(part, part->extract_context, part->parsedata.workbuf.c, part->parsedata.workbuf.len);
part->parsedata.workbuf.len = 0;
}

return c;
}

PHP_MAILPARSE_API void php_mimepart_decoder_prepare(php_mimepart *part, int do_decode, php_mimepart_extract_func_t decoder, void *ptr)
{
const mb_encoding *encoding;
Expand Down Expand Up @@ -950,7 +935,7 @@ PHP_MAILPARSE_API void php_mimepart_decoder_prepare(php_mimepart *part, int do_d
} else {
part->extract_filter = mb_convert_filter_new(
mb_no2encoding(from), mb_no2encoding(mb_no_encoding_8bit),
filter_into_work_buffer,
NULL,
NULL,
part
);
Expand All @@ -962,8 +947,9 @@ PHP_MAILPARSE_API void php_mimepart_decoder_prepare(php_mimepart *part, int do_d
PHP_MAILPARSE_API void php_mimepart_decoder_finish(php_mimepart *part)
{
if (part->extract_filter) {
mb_convert_filter_flush(part->extract_filter);
mb_convert_filter_flush_block(part->extract_filter, &part->parsedata.workbuf);
mb_convert_filter_delete(part->extract_filter);
part->extract_filter = NULL;
}
if (part->extract_func && part->parsedata.workbuf.len > 0) {
part->extract_func(part, part->extract_context, part->parsedata.workbuf.c, part->parsedata.workbuf.len);
Expand All @@ -974,15 +960,11 @@ PHP_MAILPARSE_API void php_mimepart_decoder_finish(php_mimepart *part)
PHP_MAILPARSE_API int php_mimepart_decoder_feed(php_mimepart *part, const char *buf, size_t bufsize)
{
if (buf && bufsize) {
size_t i;

if (part->extract_filter) {
for (i = 0; i < bufsize; i++) {
if (mb_convert_filter_feed(buf[i], part->extract_filter) < 0) {
zend_error(E_WARNING, "%s() - filter conversion failed. Input message is probably incorrectly encoded\n",
get_active_function_name());
return -1;
}
mb_convert_filter_feed_block(part->extract_filter, buf, bufsize, &part->parsedata.workbuf);
if (part->parsedata.workbuf.len >= MAILPARSE_BUFSIZ) {
part->extract_func(part, part->extract_context, part->parsedata.workbuf.c, part->parsedata.workbuf.len);
part->parsedata.workbuf.len = 0;
}
} else {
return part->extract_func(part, part->extract_context, buf, bufsize);
Expand Down
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