Adding upstream version 1:2.3.19.1+dfsg1.upstream/1%2.3.19.1+dfsg1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 740 insertions, 0 deletions

diff --git a/src/lib-mail/istream-attachment-extractor.c b/src/lib-mail/istream-attachment-extractor.c
new file mode 100644
index 0000000..7d4ac01
--- /dev/null
+++ b/src/lib-mail/istream-attachment-extractor.c
@@ -0,0 +1,740 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "istream-private.h"
+#include "ostream.h"
+#include "base64.h"
+#include "buffer.h"
+#include "str.h"
+#include "hash-format.h"
+#include "rfc822-parser.h"
+#include "message-parser.h"
+#include "istream-attachment-extractor.h"
+
+#define BASE64_ATTACHMENT_MAX_EXTRA_BYTES 1024
+
+enum mail_attachment_state {
+	MAIL_ATTACHMENT_STATE_NO,
+	MAIL_ATTACHMENT_STATE_MAYBE,
+	MAIL_ATTACHMENT_STATE_YES
+};
+
+enum base64_state {
+	BASE64_STATE_0 = 0,
+	BASE64_STATE_1,
+	BASE64_STATE_2,
+	BASE64_STATE_3,
+	BASE64_STATE_CR,
+	BASE64_STATE_EOB,
+	BASE64_STATE_EOM
+};
+
+struct attachment_istream_part {
+	char *content_type, *content_disposition;
+	enum mail_attachment_state state;
+	/* start offset of the message part in the original input stream */
+	uoff_t start_offset;
+
+	/* for saving attachments base64-decoded: */
+	enum base64_state base64_state;
+	unsigned int base64_line_blocks, cur_base64_blocks;
+	uoff_t base64_bytes;
+	bool base64_have_crlf; /* CRLF linefeeds */
+	bool base64_failed;
+
+	int temp_fd;
+	struct ostream *temp_output;
+	buffer_t *part_buf;
+};
+
+struct attachment_istream {
+	struct istream_private istream;
+	pool_t pool;
+
+	struct istream_attachment_settings set;
+	void *context;
+
+	struct message_parser_ctx *parser;
+	struct message_part *cur_part;
+	struct attachment_istream_part part;
+
+	bool retry_read;
+};
+
+static void stream_add_data(struct attachment_istream *astream,
+			    const void *data, size_t size)
+{
+	if (size > 0) {
+		memcpy(i_stream_alloc(&astream->istream, size), data, size);
+		astream->istream.pos += size;
+	}
+}
+
+static void parse_content_type(struct attachment_istream *astream,
+			       const struct message_header_line *hdr)
+{
+	struct rfc822_parser_context parser;
+	string_t *content_type;
+
+	if (astream->part.content_type != NULL)
+		return;
+
+	rfc822_parser_init(&parser, hdr->full_value, hdr->full_value_len, NULL);
+	rfc822_skip_lwsp(&parser);
+
+	T_BEGIN {
+		content_type = t_str_new(64);
+		(void)rfc822_parse_content_type(&parser, content_type);
+		astream->part.content_type = i_strdup(str_c(content_type));
+	} T_END;
+	rfc822_parser_deinit(&parser);
+}
+
+static void
+parse_content_disposition(struct attachment_istream *astream,
+			  const struct message_header_line *hdr)
+{
+	/* just pass it without parsing to is_attachment() callback */
+	i_free(astream->part.content_disposition);
+	astream->part.content_disposition =
+		i_strndup(hdr->full_value, hdr->full_value_len);
+}
+
+static void astream_parse_header(struct attachment_istream *astream,
+				 struct message_header_line *hdr)
+{
+	if (!hdr->continued) {
+		stream_add_data(astream, hdr->name, hdr->name_len);
+		stream_add_data(astream, hdr->middle, hdr->middle_len);
+	}
+	stream_add_data(astream, hdr->value, hdr->value_len);
+	if (!hdr->no_newline) {
+		if (hdr->crlf_newline)
+			stream_add_data(astream, "\r\n", 2);
+		else
+			stream_add_data(astream, "\n", 1);
+	}
+
+	if (hdr->continues) {
+		hdr->use_full_value = TRUE;
+		return;
+	}
+
+	if (strcasecmp(hdr->name, "Content-Type") == 0)
+		parse_content_type(astream, hdr);
+	else if (strcasecmp(hdr->name, "Content-Disposition") == 0)
+		parse_content_disposition(astream, hdr);
+}
+
+static bool astream_want_attachment(struct attachment_istream *astream,
+				    struct message_part *part)
+{
+	struct istream_attachment_header ahdr;
+
+	if ((part->flags & MESSAGE_PART_FLAG_MULTIPART) != 0) {
+		/* multiparts may contain attachments as children,
+		   but they're never themselves */
+		return FALSE;
+	}
+	if (astream->set.want_attachment == NULL)
+		return TRUE;
+
+	i_zero(&ahdr);
+	ahdr.part = part;
+	ahdr.content_type = astream->part.content_type;
+	ahdr.content_disposition = astream->part.content_disposition;
+	return astream->set.want_attachment(&ahdr, astream->context);
+}
+
+static int astream_base64_decode_lf(struct attachment_istream_part *part)
+{
+	if (part->base64_have_crlf && part->base64_state != BASE64_STATE_CR) {
+		/* mixed LF vs CRLFs */
+		return -1;
+	}
+	part->base64_state = BASE64_STATE_0;
+	if (part->cur_base64_blocks < part->base64_line_blocks) {
+		/* last line */
+		part->base64_state = BASE64_STATE_EOM;
+		return 0;
+	} else if (part->base64_line_blocks == 0) {
+		/* first line */
+		if (part->cur_base64_blocks == 0)
+			return -1;
+		part->base64_line_blocks = part->cur_base64_blocks;
+	} else if (part->cur_base64_blocks == part->base64_line_blocks) {
+		/* line is ok */
+	} else {
+		return -1;
+	}
+	part->cur_base64_blocks = 0;
+	return 1;
+}
+
+static int
+astream_try_base64_decode_char(struct attachment_istream_part *part,
+			       size_t pos, char chr)
+{
+	switch (part->base64_state) {
+	case BASE64_STATE_0:
+		if (base64_is_valid_char(chr))
+			part->base64_state++;
+		else if (chr == '\r')
+			part->base64_state = BASE64_STATE_CR;
+		else if (chr == '\n') {
+			return astream_base64_decode_lf(part);
+		} else {
+			return -1;
+		}
+		break;
+	case BASE64_STATE_1:
+		if (!base64_is_valid_char(chr))
+			return -1;
+		part->base64_state++;
+		break;
+	case BASE64_STATE_2:
+		if (base64_is_valid_char(chr))
+			part->base64_state++;
+		else if (chr == '=')
+			part->base64_state = BASE64_STATE_EOB;
+		else
+			return -1;
+		break;
+	case BASE64_STATE_3:
+		part->base64_bytes = part->temp_output->offset + pos + 1;
+		if (base64_is_valid_char(chr)) {
+			part->base64_state = BASE64_STATE_0;
+			part->cur_base64_blocks++;
+		} else if (chr == '=') {
+			part->base64_state = BASE64_STATE_EOM;
+			part->cur_base64_blocks++;
+
+			if (part->cur_base64_blocks > part->base64_line_blocks &&
+			    part->base64_line_blocks > 0) {
+				/* too many blocks */
+				return -1;
+			}
+			return 0;
+		} else {
+			return -1;
+		}
+		break;
+	case BASE64_STATE_CR:
+		if (chr != '\n')
+			return -1;
+		if (!part->base64_have_crlf) {
+			if (part->base64_line_blocks != 0) {
+				/* mixed LF vs CRLFs */
+				return -1;
+			}
+			part->base64_have_crlf = TRUE;
+		}
+		return astream_base64_decode_lf(part);
+	case BASE64_STATE_EOB:
+		if (chr != '=')
+			return -1;
+
+		part->base64_bytes = part->temp_output->offset + pos + 1;
+		part->base64_state = BASE64_STATE_EOM;
+		part->cur_base64_blocks++;
+
+		if (part->cur_base64_blocks > part->base64_line_blocks &&
+		    part->base64_line_blocks > 0) {
+			/* too many blocks */
+			return -1;
+		}
+		return 0;
+	case BASE64_STATE_EOM:
+		i_unreached();
+	}
+	return 1;
+}
+
+static void
+astream_try_base64_decode(struct attachment_istream_part *part,
+			  const unsigned char *data, size_t size)
+{
+	size_t i;
+	int ret;
+
+	if (part->base64_failed || part->base64_state == BASE64_STATE_EOM)
+		return;
+
+	for (i = 0; i < size; i++) {
+		ret = astream_try_base64_decode_char(part, i, (char)data[i]);
+		if (ret <= 0) {
+			if (ret < 0)
+				part->base64_failed = TRUE;
+			break;
+		}
+	}
+}
+
+static int astream_open_output(struct attachment_istream *astream)
+{
+	int fd;
+
+	i_assert(astream->part.temp_fd == -1);
+
+	fd = astream->set.open_temp_fd(astream->context);
+	if (fd == -1)
+		return -1;
+
+	astream->part.temp_fd = fd;
+	astream->part.temp_output = o_stream_create_fd(fd, 0);
+	o_stream_cork(astream->part.temp_output);
+	return 0;
+}
+
+static void astream_add_body(struct attachment_istream *astream,
+			     const struct message_block *block)
+{
+	struct attachment_istream_part *part = &astream->part;
+	buffer_t *part_buf;
+	size_t new_size;
+
+	switch (part->state) {
+	case MAIL_ATTACHMENT_STATE_NO:
+		stream_add_data(astream, block->data, block->size);
+		break;
+	case MAIL_ATTACHMENT_STATE_MAYBE:
+		/* we'll write data to in-memory buffer until we reach
+		   attachment min_size */
+		if (part->part_buf == NULL) {
+			part->part_buf =
+				buffer_create_dynamic(default_pool,
+						      astream->set.min_size);
+		}
+		part_buf = part->part_buf;
+		new_size = part_buf->used + block->size;
+		if (new_size < astream->set.min_size) {
+			buffer_append(part_buf, block->data, block->size);
+			break;
+		}
+		/* attachment is large enough. we'll first copy the buffered
+		   data from memory to temp file */
+		if (astream_open_output(astream) < 0) {
+			/* failed, fallback to just saving it inline */
+			part->state = MAIL_ATTACHMENT_STATE_NO;
+			stream_add_data(astream, part_buf->data, part_buf->used);
+			stream_add_data(astream, block->data, block->size);
+			break;
+		}
+		part->state = MAIL_ATTACHMENT_STATE_YES;
+		astream_try_base64_decode(part, part_buf->data, part_buf->used);
+		hash_format_loop(astream->set.hash_format,
+				 part_buf->data, part_buf->used);
+		o_stream_nsend(part->temp_output,
+			       part_buf->data, part_buf->used);
+		buffer_set_used_size(part_buf, 0);
+		/* fall through - write the new data to temp file */
+	case MAIL_ATTACHMENT_STATE_YES:
+		astream_try_base64_decode(part, block->data, block->size);
+		hash_format_loop(astream->set.hash_format,
+				 block->data, block->size);
+		o_stream_nsend(part->temp_output, block->data, block->size);
+		break;
+	}
+}
+
+static int astream_decode_base64(struct attachment_istream *astream,
+				 buffer_t **extra_buf_r)
+{
+	struct attachment_istream_part *part = &astream->part;
+	struct base64_decoder b64dec;
+	struct istream *input, *base64_input;
+	struct ostream *output;
+	const unsigned char *data;
+	size_t size;
+	ssize_t ret;
+	buffer_t *buf;
+	int outfd;
+	bool failed = FALSE;
+
+	*extra_buf_r = NULL;
+
+	if (part->base64_bytes < astream->set.min_size ||
+	    part->temp_output->offset > part->base64_bytes +
+	    				BASE64_ATTACHMENT_MAX_EXTRA_BYTES) {
+		/* only a small part of the MIME part is base64-encoded. */
+		return -1;
+	}
+
+	if (part->base64_line_blocks == 0) {
+		/* only one line of base64 */
+		part->base64_line_blocks = part->cur_base64_blocks;
+		i_assert(part->base64_line_blocks > 0);
+	}
+
+	/* decode base64 data and write it to another temp file */
+	outfd = astream->set.open_temp_fd(astream->context);
+	if (outfd == -1)
+		return -1;
+
+	buf = buffer_create_dynamic(default_pool, 1024);
+	input = i_stream_create_fd(part->temp_fd, IO_BLOCK_SIZE);
+	base64_input = i_stream_create_limit(input, part->base64_bytes);
+	output = o_stream_create_fd_file(outfd, 0, FALSE);
+	o_stream_cork(output);
+
+	base64_decode_init(&b64dec, &base64_scheme, 0);
+	hash_format_reset(astream->set.hash_format);
+	size_t bytes_needed = 1;
+	while ((ret = i_stream_read_bytes(base64_input, &data, &size,
+					  bytes_needed)) > 0) {
+		buffer_set_used_size(buf, 0);
+		if (base64_decode_more(&b64dec, data, size, &size, buf) < 0) {
+			i_error("istream-attachment: BUG: "
+				"Attachment base64 data unexpectedly broke");
+			failed = TRUE;
+			break;
+		}
+		i_stream_skip(base64_input, size);
+		o_stream_nsend(output, buf->data, buf->used);
+		hash_format_loop(astream->set.hash_format,
+				 buf->data, buf->used);
+		bytes_needed = i_stream_get_data_size(base64_input) + 1;
+	}
+	if (ret != -1) {
+		i_assert(failed);
+	} else if (base64_input->stream_errno != 0) {
+		i_error("istream-attachment: read(%s) failed: %s",
+			i_stream_get_name(base64_input),
+			i_stream_get_error(base64_input));
+		failed = TRUE;
+	}
+	if (base64_decode_finish(&b64dec) < 0) {
+		i_error("istream-attachment: BUG: "
+			"Attachment base64 data unexpectedly broke");
+		failed = TRUE;
+	}
+	if (o_stream_finish(output) < 0) {
+		i_error("istream-attachment: write(%s) failed: %s",
+			o_stream_get_name(output), o_stream_get_error(output));
+		failed = TRUE;
+	}
+
+	buffer_free(&buf);
+	i_stream_unref(&base64_input);
+	o_stream_unref(&output);
+
+	if (input->v_offset != part->temp_output->offset && !failed) {
+		/* write the rest of the data to the message stream */
+		*extra_buf_r = buffer_create_dynamic(default_pool, 1024);
+		while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
+			buffer_append(*extra_buf_r, data, size);
+			i_stream_skip(input, size);
+		}
+		i_assert(ret == -1);
+		if (input->stream_errno != 0) {
+			i_error("istream-attachment: read(%s) failed: %s",
+				i_stream_get_name(input),
+				i_stream_get_error(input));
+			failed = TRUE;
+		}
+	}
+	i_stream_unref(&input);
+
+	if (failed) {
+		i_close_fd(&outfd);
+		return -1;
+	}
+
+	/* successfully wrote it. switch to using it. */
+	o_stream_destroy(&part->temp_output);
+	i_close_fd(&part->temp_fd);
+	part->temp_fd = outfd;
+	return 0;
+}
+
+static int
+astream_part_finish(struct attachment_istream *astream, const char **error_r)
+{
+	struct attachment_istream_part *part = &astream->part;
+	struct istream_attachment_info info;
+	struct istream *input;
+	struct ostream *output;
+	string_t *digest_str;
+	buffer_t *extra_buf = NULL;
+	const unsigned char *data;
+	size_t size;
+	int ret = 0;
+
+	if (o_stream_finish(part->temp_output) < 0) {
+		*error_r = t_strdup_printf("write(%s) failed: %s",
+					   o_stream_get_name(part->temp_output),
+					   o_stream_get_error(part->temp_output));
+		return -1;
+	}
+
+	i_zero(&info);
+	info.start_offset = astream->part.start_offset;
+	/* base64_bytes contains how many valid base64 bytes there are so far.
+	   if the base64 ends properly, it'll specify how much of the MIME part
+	   is saved as an attachment. the rest of the data (typically
+	   linefeeds) is added back to main stream */
+	info.encoded_size = part->base64_bytes;
+	/* get the hash before base64-decoder resets it */
+	digest_str = t_str_new(128);
+	hash_format_write(astream->set.hash_format, digest_str);
+	info.hash = str_c(digest_str);
+
+	/* if it looks like we can decode base64 without any data loss,
+	   do it and write the decoded data to another temp file. */
+	if (!part->base64_failed) {
+		if (part->base64_state == BASE64_STATE_0 &&
+		    part->base64_bytes > 0) {
+			/* there is no trailing LF or '=' characters,
+			   but it's not completely empty */
+			part->base64_state = BASE64_STATE_EOM;
+		}
+		if (part->base64_state == BASE64_STATE_EOM) {
+			/* base64 data looks ok. */
+			if (astream_decode_base64(astream, &extra_buf) < 0)
+				part->base64_failed = TRUE;
+		} else {
+			part->base64_failed = TRUE;
+		}
+	}
+
+	/* open attachment output file */
+	info.part = astream->cur_part;
+	if (!part->base64_failed) {
+		info.base64_blocks_per_line = part->base64_line_blocks;
+		info.base64_have_crlf = part->base64_have_crlf;
+		/* base64-decoder updated the hash, use it */
+		str_truncate(digest_str, 0);
+		hash_format_write(astream->set.hash_format, digest_str);
+		info.hash = str_c(digest_str);
+	} else {
+		/* couldn't decode base64, so write the entire MIME part
+		   as attachment */
+		info.encoded_size = part->temp_output->offset;
+	}
+	if (astream->set.open_attachment_ostream(&info, &output, error_r,
+						 astream->context) < 0) {
+		buffer_free(&extra_buf);
+		return -1;
+	}
+
+	/* copy data to attachment from temp file */
+	input = i_stream_create_fd(part->temp_fd, IO_BLOCK_SIZE);
+	while (i_stream_read_more(input, &data, &size) > 0) {
+		o_stream_nsend(output, data, size);
+		i_stream_skip(input, size);
+	}
+
+	if (input->stream_errno != 0) {
+		*error_r = t_strdup_printf("read(%s) failed: %s",
+			i_stream_get_name(input), i_stream_get_error(input));
+		ret = -1;
+	}
+	i_stream_destroy(&input);
+
+	if (astream->set.close_attachment_ostream(output, ret == 0, error_r,
+						  astream->context) < 0)
+		ret = -1;
+	if (ret == 0 && extra_buf != NULL)
+		stream_add_data(astream, extra_buf->data, extra_buf->used);
+	buffer_free(&extra_buf);
+	return ret;
+}
+
+static void astream_part_reset(struct attachment_istream *astream)
+{
+	struct attachment_istream_part *part = &astream->part;
+
+	o_stream_destroy(&part->temp_output);
+	i_close_fd(&part->temp_fd);
+
+	i_free_and_null(part->content_type);
+	i_free_and_null(part->content_disposition);
+	buffer_free(&part->part_buf);
+
+	i_zero(part);
+	part->temp_fd = -1;
+	hash_format_reset(astream->set.hash_format);
+}
+
+static int
+astream_end_of_part(struct attachment_istream *astream, const char **error_r)
+{
+	struct attachment_istream_part *part = &astream->part;
+	size_t old_size;
+	int ret = 0;
+
+	/* MIME part changed. we're now parsing the end of a boundary,
+	   possibly followed by message epilogue */
+	switch (part->state) {
+	case MAIL_ATTACHMENT_STATE_NO:
+		break;
+	case MAIL_ATTACHMENT_STATE_MAYBE:
+		/* MIME part wasn't large enough to be an attachment */
+		if (part->part_buf != NULL) {
+			stream_add_data(astream, part->part_buf->data,
+					part->part_buf->used);
+			ret = part->part_buf->used > 0 ? 1 : 0;
+		}
+		break;
+	case MAIL_ATTACHMENT_STATE_YES:
+		old_size = astream->istream.pos - astream->istream.skip;
+		if (astream_part_finish(astream, error_r) < 0)
+			ret = -1;
+		else {
+			/* finished base64 may have added a few more trailing
+			   bytes to the stream */
+			ret = astream->istream.pos -
+				astream->istream.skip - old_size;
+		}
+		break;
+	}
+	part->state = MAIL_ATTACHMENT_STATE_NO;
+	astream_part_reset(astream);
+	return ret;
+}
+
+static int astream_read_next(struct attachment_istream *astream, bool *retry_r)
+{
+	struct istream_private *stream = &astream->istream;
+	struct message_block block;
+	size_t old_size, new_size;
+	const char *error;
+	int ret;
+
+	*retry_r = FALSE;
+
+	if (stream->pos - stream->skip >= i_stream_get_max_buffer_size(&stream->istream))
+		return -2;
+
+	old_size = stream->pos - stream->skip;
+	switch (message_parser_parse_next_block(astream->parser, &block)) {
+	case -1:
+		/* done / error */
+		ret = astream_end_of_part(astream, &error);
+		if (ret > 0) {
+			/* final data */
+			new_size = stream->pos - stream->skip;
+			return new_size - old_size;
+		}
+		stream->istream.eof = TRUE;
+		stream->istream.stream_errno = stream->parent->stream_errno;
+
+		if (ret < 0) {
+			io_stream_set_error(&stream->iostream, "%s", error);
+			stream->istream.stream_errno = EIO;
+		}
+		astream->cur_part = NULL;
+		return -1;
+	case 0:
+		/* need more data */
+		return 0;
+	default:
+		break;
+	}
+
+	if (block.part != astream->cur_part && astream->cur_part != NULL) {
+		/* end of a MIME part */
+		if (astream_end_of_part(astream, &error) < 0) {
+			io_stream_set_error(&stream->iostream, "%s", error);
+			stream->istream.stream_errno = EIO;
+			return -1;
+		}
+	}
+	astream->cur_part = block.part;
+
+	if (block.hdr != NULL) {
+		/* parsing a header */
+		astream_parse_header(astream, block.hdr);
+	} else if (block.size == 0) {
+		/* end of headers */
+		if (astream_want_attachment(astream, block.part)) {
+			astream->part.state = MAIL_ATTACHMENT_STATE_MAYBE;
+			astream->part.start_offset = stream->parent->v_offset;
+		}
+	} else {
+		astream_add_body(astream, &block);
+	}
+	new_size = stream->pos - stream->skip;
+	*retry_r = new_size == old_size;
+	return new_size - old_size;
+}
+
+static ssize_t
+i_stream_attachment_extractor_read(struct istream_private *stream)
+{
+	struct attachment_istream *astream =
+		(struct attachment_istream *)stream;
+	bool retry;
+	ssize_t ret;
+
+	do {
+		ret = astream_read_next(astream, &retry);
+	} while (retry && astream->set.drain_parent_input);
+
+	astream->retry_read = retry;
+	return ret;
+}
+
+static void i_stream_attachment_extractor_close(struct iostream_private *stream,
+						bool close_parent)
+{
+	struct attachment_istream *astream =
+		(struct attachment_istream *)stream;
+	struct message_part *parts;
+
+	if (astream->parser != NULL) {
+		message_parser_deinit(&astream->parser, &parts);
+	}
+	hash_format_deinit_free(&astream->set.hash_format);
+	pool_unref(&astream->pool);
+	if (close_parent)
+		i_stream_close(astream->istream.parent);
+}
+
+struct istream *
+i_stream_create_attachment_extractor(struct istream *input,
+				     struct istream_attachment_settings *set,
+				     void *context)
+{
+	const struct message_parser_settings parser_set = {
+		.flags = MESSAGE_PARSER_FLAG_INCLUDE_MULTIPART_BLOCKS |
+			MESSAGE_PARSER_FLAG_INCLUDE_BOUNDARIES,
+	};
+	struct attachment_istream *astream;
+
+	i_assert(set->min_size > 0);
+	i_assert(set->hash_format != NULL);
+	i_assert(set->open_attachment_ostream != NULL);
+	i_assert(set->close_attachment_ostream != NULL);
+
+	astream = i_new(struct attachment_istream, 1);
+	astream->part.temp_fd = -1;
+	astream->set = *set;
+	astream->context = context;
+	astream->retry_read = TRUE;
+
+	/* make sure the caller doesn't try to double-free this */
+	set->hash_format = NULL;
+
+	astream->istream.max_buffer_size = input->real_stream->max_buffer_size;
+
+	astream->istream.read = i_stream_attachment_extractor_read;
+	astream->istream.iostream.close = i_stream_attachment_extractor_close;
+
+	astream->istream.istream.readable_fd = FALSE;
+	astream->istream.istream.blocking = input->blocking;
+	astream->istream.istream.seekable = FALSE;
+
+	astream->pool = pool_alloconly_create("istream attachment", 1024);
+	astream->parser = message_parser_init(astream->pool, input, &parser_set);
+	return i_stream_create(&astream->istream, input,
+			       i_stream_get_fd(input), 0);
+}
+
+bool i_stream_attachment_extractor_can_retry(struct istream *input)
+{
+	struct attachment_istream *astream =
+		(struct attachment_istream *)input->real_stream;
+
+	return astream->retry_read;
+}