message-decoder.c revision 5cbefc6537aefbf1491416c433de00fc3e649a13
/* Copyright (c) 2006-2009 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "buffer.h"
#include "base64.h"
#include "str.h"
#include "unichar.h"
#include "charset-utf8.h"
#include "quoted-printable.h"
#include "rfc822-parser.h"
#include "rfc2231-parser.h"
#include "message-parser.h"
#include "message-header-decode.h"
#include "message-decoder.h"
enum content_type {
CONTENT_TYPE_UNKNOWN = 0,
CONTENT_TYPE_BINARY,
CONTENT_TYPE_QP,
CONTENT_TYPE_BASE64
};
/* base64 takes max 4 bytes per character, q-p takes max 3. */
#define MAX_ENCODING_BUF_SIZE 3
/* UTF-8 takes max 5 bytes per character. Not sure about others, but I'd think
10 is more than enough for everyone.. */
#define MAX_TRANSLATION_BUF_SIZE 10
struct message_decoder_context {
enum message_decoder_flags flags;
struct message_part *prev_part;
struct message_header_line hdr;
buffer_t *buf, *buf2;
char *charset_trans_charset;
struct charset_translation *charset_trans;
char translation_buf[MAX_TRANSLATION_BUF_SIZE];
unsigned int translation_size;
char encoding_buf[MAX_ENCODING_BUF_SIZE];
unsigned int encoding_size;
char *content_charset;
enum content_type content_type;
unsigned int charset_utf8:1;
unsigned int binary_input:1;
};
struct message_decoder_context *
message_decoder_init(enum message_decoder_flags flags)
{
struct message_decoder_context *ctx;
ctx = i_new(struct message_decoder_context, 1);
ctx->flags = flags;
ctx->buf = buffer_create_dynamic(default_pool, 8192);
ctx->buf2 = buffer_create_dynamic(default_pool, 8192);
return ctx;
}
void message_decoder_deinit(struct message_decoder_context **_ctx)
{
struct message_decoder_context *ctx = *_ctx;
*_ctx = NULL;
if (ctx->charset_trans != NULL)
charset_to_utf8_end(&ctx->charset_trans);
buffer_free(&ctx->buf);
buffer_free(&ctx->buf2);
i_free(ctx->charset_trans_charset);
i_free(ctx->content_charset);
i_free(ctx);
}
static void
parse_content_transfer_encoding(struct message_decoder_context *ctx,
struct message_header_line *hdr)
{
struct rfc822_parser_context parser;
string_t *value;
value = t_str_new(64);
rfc822_parser_init(&parser, hdr->full_value, hdr->full_value_len, NULL);
(void)rfc822_skip_lwsp(&parser);
(void)rfc822_parse_mime_token(&parser, value);
ctx->content_type = CONTENT_TYPE_UNKNOWN;
switch (str_len(value)) {
case 4:
if (i_memcasecmp(str_data(value), "7bit", 4) == 0 ||
i_memcasecmp(str_data(value), "8bit", 4) == 0)
ctx->content_type = CONTENT_TYPE_BINARY;
break;
case 6:
if (i_memcasecmp(str_data(value), "base64", 6) == 0)
ctx->content_type = CONTENT_TYPE_BASE64;
else if (i_memcasecmp(str_data(value), "binary", 6) == 0)
ctx->content_type = CONTENT_TYPE_BINARY;
break;
case 16:
if (i_memcasecmp(str_data(value), "quoted-printable", 16) == 0)
ctx->content_type = CONTENT_TYPE_QP;
break;
}
}
static void
parse_content_type(struct message_decoder_context *ctx,
struct message_header_line *hdr)
{
struct rfc822_parser_context parser;
const char *const *results;
string_t *str;
if (ctx->content_charset != NULL)
return;
rfc822_parser_init(&parser, hdr->full_value, hdr->full_value_len, NULL);
(void)rfc822_skip_lwsp(&parser);
str = t_str_new(64);
if (rfc822_parse_content_type(&parser, str) <= 0)
return;
(void)rfc2231_parse(&parser, &results);
for (; *results != NULL; results += 2) {
if (strcasecmp(results[0], "charset") == 0) {
ctx->content_charset = i_strdup(results[1]);
ctx->charset_utf8 = charset_is_utf8(results[1]);
break;
}
}
}
static bool message_decode_header(struct message_decoder_context *ctx,
struct message_header_line *hdr,
struct message_block *output)
{
bool dtcase = (ctx->flags & MESSAGE_DECODER_FLAG_DTCASE) != 0;
size_t value_len;
if (hdr->continues) {
hdr->use_full_value = TRUE;
return FALSE;
}
T_BEGIN {
if (hdr->name_len == 12 &&
strcasecmp(hdr->name, "Content-Type") == 0)
parse_content_type(ctx, hdr);
if (hdr->name_len == 25 &&
strcasecmp(hdr->name, "Content-Transfer-Encoding") == 0)
parse_content_transfer_encoding(ctx, hdr);
} T_END;
buffer_set_used_size(ctx->buf, 0);
message_header_decode_utf8(hdr->full_value, hdr->full_value_len,
ctx->buf, dtcase);
value_len = ctx->buf->used;
if (dtcase) {
(void)uni_utf8_to_decomposed_titlecase(hdr->name, hdr->name_len,
ctx->buf);
buffer_append_c(ctx->buf, '\0');
}
ctx->hdr = *hdr;
ctx->hdr.full_value = ctx->buf->data;
ctx->hdr.full_value_len = value_len;
ctx->hdr.value_len = 0;
if (dtcase) {
ctx->hdr.name = CONST_PTR_OFFSET(ctx->buf->data,
ctx->hdr.full_value_len);
ctx->hdr.name_len = ctx->buf->used - 1 - value_len;
}
output->hdr = &ctx->hdr;
return TRUE;
}
static void translation_buf_decode(struct message_decoder_context *ctx,
const unsigned char **data, size_t *size)
{
unsigned char trans_buf[MAX_TRANSLATION_BUF_SIZE+1];
unsigned int data_wanted, skip;
size_t trans_size;
/* @UNSAFE: move the previously untranslated bytes to trans_buf
and see if we have now enough data to get the next character
translated */
memcpy(trans_buf, ctx->translation_buf, ctx->translation_size);
data_wanted = sizeof(trans_buf) - ctx->translation_size;
if (data_wanted > *size)
data_wanted = *size;
memcpy(trans_buf + ctx->translation_size, *data, data_wanted);
trans_size = ctx->translation_size + data_wanted;
(void)charset_to_utf8(ctx->charset_trans, trans_buf,
&trans_size, ctx->buf2);
i_assert(trans_size > ctx->translation_size);
skip = trans_size - ctx->translation_size;
i_assert(*size >= skip);
*data += skip;
*size -= skip;
ctx->translation_size = 0;
}
static void
message_decode_body_init_charset(struct message_decoder_context *ctx,
struct message_part *part)
{
enum charset_flags flags;
if (ctx->charset_utf8)
return;
if (ctx->charset_trans != NULL &&
strcasecmp(ctx->content_charset, ctx->charset_trans_charset) == 0) {
/* already have the correct translation selected */
return;
}
if (ctx->charset_trans != NULL)
charset_to_utf8_end(&ctx->charset_trans);
i_free_and_null(ctx->charset_trans_charset);
ctx->binary_input = ctx->content_charset == NULL &&
(ctx->flags & MESSAGE_DECODER_FLAG_RETURN_BINARY) != 0 &&
(part->flags & (MESSAGE_PART_FLAG_TEXT |
MESSAGE_PART_FLAG_MESSAGE_RFC822)) == 0;
if (ctx->binary_input)
return;
flags = (ctx->flags & MESSAGE_DECODER_FLAG_DTCASE) != 0 ?
CHARSET_FLAG_DECOMP_TITLECASE : 0;
ctx->charset_trans_charset = i_strdup(ctx->content_charset != NULL ?
ctx->content_charset : "UTF-8");
if (charset_to_utf8_begin(ctx->charset_trans_charset,
flags, &ctx->charset_trans) < 0)
ctx->charset_trans = NULL;
}
static bool message_decode_body(struct message_decoder_context *ctx,
struct message_block *input,
struct message_block *output)
{
unsigned char new_buf[MAX_ENCODING_BUF_SIZE+1];
const unsigned char *data = NULL;
size_t pos, size = 0, skip = 0;
int ret;
if (ctx->encoding_size != 0) {
/* @UNSAFE */
memcpy(new_buf, ctx->encoding_buf, ctx->encoding_size);
skip = sizeof(new_buf) - ctx->encoding_size;
if (skip > input->size)
skip = input->size;
memcpy(new_buf + ctx->encoding_size, input->data, skip);
}
switch (ctx->content_type) {
case CONTENT_TYPE_UNKNOWN:
/* just skip this body */
return FALSE;
case CONTENT_TYPE_BINARY:
data = input->data;
size = pos = input->size;
break;
case CONTENT_TYPE_QP:
buffer_set_used_size(ctx->buf, 0);
if (ctx->encoding_size != 0) {
quoted_printable_decode(new_buf,
ctx->encoding_size + skip,
&pos, ctx->buf);
i_assert(pos >= ctx->encoding_size);
skip = pos - ctx->encoding_size;
}
quoted_printable_decode(input->data + skip, input->size - skip,
&pos, ctx->buf);
pos += skip;
data = ctx->buf->data;
size = ctx->buf->used;
break;
case CONTENT_TYPE_BASE64:
buffer_set_used_size(ctx->buf, 0);
if (ctx->encoding_size != 0) {
if (base64_decode(new_buf, ctx->encoding_size + skip,
&pos, ctx->buf) < 0) {
/* corrupted base64 data, don't bother with
the rest of it */
return FALSE;
}
i_assert(pos >= ctx->encoding_size);
skip = pos - ctx->encoding_size;
}
ret = base64_decode(input->data + skip, input->size - skip,
&pos, ctx->buf);
if (ret < 0) {
/* corrupted base64 data, don't bother with
the rest of it */
return FALSE;
}
if (ret == 0) {
/* end of base64 input */
pos = input->size - skip;
}
pos += skip;
data = ctx->buf->data;
size = ctx->buf->used;
break;
}
if (pos != input->size) {
/* @UNSAFE */
i_assert(pos < input->size);
ctx->encoding_size = input->size - pos;
i_assert(ctx->encoding_size <= sizeof(ctx->encoding_buf));
memcpy(ctx->encoding_buf, input->data + pos,
ctx->encoding_size);
} else {
ctx->encoding_size = 0;
}
if (ctx->binary_input) {
output->data = data;
output->size = size;
} else if (ctx->charset_utf8) {
buffer_set_used_size(ctx->buf2, 0);
if ((ctx->flags & MESSAGE_DECODER_FLAG_DTCASE) != 0) {
(void)uni_utf8_to_decomposed_titlecase(data, size,
ctx->buf2);
output->data = ctx->buf2->data;
output->size = ctx->buf2->used;
} else if (uni_utf8_get_valid_data(data, size, ctx->buf2)) {
output->data = data;
output->size = size;
} else {
output->data = ctx->buf2->data;
output->size = ctx->buf2->used;
}
} else if (ctx->charset_trans == NULL) {
/* unknown charset */
buffer_set_used_size(ctx->buf2, 0);
if (uni_utf8_get_valid_data(data, size, ctx->buf2)) {
output->data = data;
output->size = size;
} else {
output->data = ctx->buf2->data;
output->size = ctx->buf2->used;
}
} else {
buffer_set_used_size(ctx->buf2, 0);
if (ctx->translation_size != 0)
translation_buf_decode(ctx, &data, &size);
pos = size;
(void)charset_to_utf8(ctx->charset_trans,
data, &pos, ctx->buf2);
if (pos != size) {
ctx->translation_size = size - pos;
i_assert(ctx->translation_size <=
sizeof(ctx->translation_buf));
memcpy(ctx->translation_buf, data + pos,
ctx->translation_size);
}
output->data = ctx->buf2->data;
output->size = ctx->buf2->used;
}
output->hdr = NULL;
return TRUE;
}
bool message_decoder_decode_next_block(struct message_decoder_context *ctx,
struct message_block *input,
struct message_block *output)
{
if (input->part != ctx->prev_part) {
/* MIME part changed. */
message_decoder_decode_reset(ctx);
}
output->part = input->part;
ctx->prev_part = input->part;
if (input->hdr != NULL)
return message_decode_header(ctx, input->hdr, output);
else if (input->size != 0)
return message_decode_body(ctx, input, output);
else {
output->hdr = NULL;
output->size = 0;
message_decode_body_init_charset(ctx, input->part);
return TRUE;
}
}
void message_decoder_decode_reset(struct message_decoder_context *ctx)
{
i_free_and_null(ctx->content_charset);
ctx->content_type = CONTENT_TYPE_BINARY;
ctx->charset_utf8 = TRUE;
ctx->encoding_size = 0;
}