1 files changed, 339 insertions, 0 deletions

diff --git a/src/lib-ssl-iostream/ostream-openssl.c b/src/lib-ssl-iostream/ostream-openssl.c
new file mode 100644
index 0000000..8434a9b
--- /dev/null
+++ b/src/lib-ssl-iostream/ostream-openssl.c
@@ -0,0 +1,339 @@
+/* Copyright (c) 2009-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "buffer.h"
+#include "istream.h"
+#include "ostream-private.h"
+#include "iostream-openssl.h"
+
+struct ssl_ostream {
+	struct ostream_private ostream;
+	struct ssl_iostream *ssl_io;
+	buffer_t *buffer;
+
+	bool shutdown:1;
+};
+
+static void
+o_stream_ssl_close(struct iostream_private *stream, bool close_parent)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)stream;
+
+	if (close_parent)
+		o_stream_close(sstream->ssl_io->plain_output);
+}
+
+static void o_stream_ssl_destroy(struct iostream_private *stream)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)stream;
+	struct istream *ssl_input = sstream->ssl_io->ssl_input;
+
+	openssl_iostream_shutdown(sstream->ssl_io);
+	sstream->ssl_io->ssl_output = NULL;
+	i_stream_unref(&ssl_input);
+	ssl_iostream_unref(&sstream->ssl_io);
+	buffer_free(&sstream->buffer);
+}
+
+static size_t get_buffer_avail_size(const struct ssl_ostream *sstream)
+{
+	if (sstream->ostream.max_buffer_size == 0) {
+		if (sstream->buffer == NULL)
+			return 0;
+		/* we're requested to use whatever space is available in
+		   the buffer */
+		return buffer_get_writable_size(sstream->buffer) - sstream->buffer->used;
+	} else {
+		size_t buffer_used = (sstream->buffer == NULL ? 0 :
+				      sstream->buffer->used);
+		return sstream->ostream.max_buffer_size > buffer_used ?
+			sstream->ostream.max_buffer_size - buffer_used : 0;
+	}
+}
+
+static size_t
+o_stream_ssl_buffer(struct ssl_ostream *sstream, const struct const_iovec *iov,
+		    unsigned int iov_count, size_t bytes_sent)
+{
+	size_t avail, skip_left, size;
+	unsigned int i;
+
+	if (sstream->buffer == NULL)
+		sstream->buffer = buffer_create_dynamic(default_pool,
+			I_MIN(IO_BLOCK_SIZE, sstream->ostream.max_buffer_size));
+
+	skip_left = bytes_sent;
+	for (i = 0; i < iov_count; i++) {
+		if (skip_left < iov[i].iov_len)
+			break;
+		skip_left -= iov[i].iov_len;
+	}
+
+	avail = get_buffer_avail_size(sstream);
+	if (i < iov_count && skip_left > 0) {
+		size = I_MIN(iov[i].iov_len - skip_left, avail);
+		buffer_append(sstream->buffer,
+			      CONST_PTR_OFFSET(iov[i].iov_base, skip_left),
+			      size);
+		bytes_sent += size;
+		avail -= size;
+		if (size != iov[i].iov_len)
+			i = iov_count;
+	}
+	if (avail > 0)
+		o_stream_set_flush_pending(sstream->ssl_io->plain_output, TRUE);
+
+	for (; i < iov_count; i++) {
+		size = I_MIN(iov[i].iov_len, avail);
+		buffer_append(sstream->buffer, iov[i].iov_base, size);
+		bytes_sent += size;
+		avail -= size;
+
+		if (size != iov[i].iov_len)
+			break;
+	}
+
+	sstream->ostream.ostream.offset += bytes_sent;
+	return bytes_sent;
+}
+
+static int o_stream_ssl_flush_buffer(struct ssl_ostream *sstream)
+{
+	struct ssl_iostream *ssl_io = sstream->ssl_io;
+	size_t pos = 0;
+	int ret = 1;
+
+	i_assert(!sstream->shutdown);
+
+	while (pos < sstream->buffer->used) {
+		/* we're writing plaintext data to OpenSSL, which it encrypts
+		   and writes to bio_int's buffer. ssl_iostream_bio_sync()
+		   reads it from there and adds to plain_output stream. */
+		ret = SSL_write(ssl_io->ssl,
+				CONST_PTR_OFFSET(sstream->buffer->data, pos),
+				sstream->buffer->used - pos);
+		if (ret <= 0) {
+			ret = openssl_iostream_handle_error(
+				ssl_io, ret, OPENSSL_IOSTREAM_SYNC_TYPE_WRITE,
+				"SSL_write");
+			if (ret < 0) {
+				io_stream_set_error(
+					&sstream->ostream.iostream,
+					"%s", ssl_io->last_error);
+				sstream->ostream.ostream.stream_errno = errno;
+				break;
+			}
+			if (ret == 0)
+				break;
+		} else {
+			pos += ret;
+			ret = openssl_iostream_bio_sync(
+				ssl_io, OPENSSL_IOSTREAM_SYNC_TYPE_WRITE);
+			if (ret < 0) {
+				i_assert(ssl_io->plain_stream_errstr != NULL &&
+					 ssl_io->plain_stream_errno != 0);
+				io_stream_set_error(
+					&sstream->ostream.iostream,
+					"%s", ssl_io->plain_stream_errstr);
+				sstream->ostream.ostream.stream_errno =
+					ssl_io->plain_stream_errno;
+				break;
+			}
+		}
+	}
+	buffer_delete(sstream->buffer, 0, pos);
+	return ret <= 0 ? ret : 1;
+}
+
+static int o_stream_ssl_flush(struct ostream_private *stream)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)stream;
+	struct ssl_iostream *ssl_io = sstream->ssl_io;
+	struct ostream *plain_output = ssl_io->plain_output;
+	int ret = 1;
+
+	if (!ssl_io->handshaked) {
+		if ((ret = ssl_iostream_handshake(ssl_io)) < 0) {
+			/* handshake failed */
+			i_assert(errno != 0);
+			io_stream_set_error(&stream->iostream,
+					    "%s", ssl_io->last_error);
+			stream->ostream.stream_errno = errno;
+			return ret;
+		}
+	}
+	if (ret > 0 &&
+	    openssl_iostream_bio_sync(
+		ssl_io, OPENSSL_IOSTREAM_SYNC_TYPE_HANDSHAKE) < 0) {
+		i_assert(ssl_io->plain_stream_errno != 0 &&
+			 ssl_io->plain_stream_errstr != NULL);
+		io_stream_set_error(&stream->iostream,
+				    "%s", ssl_io->plain_stream_errstr);
+		stream->ostream.stream_errno = ssl_io->plain_stream_errno;
+		return -1;
+	}
+
+	if (ret > 0 && sstream->buffer != NULL && sstream->buffer->used > 0) {
+		/* we can try to send some of our buffered data */
+		ret = o_stream_ssl_flush_buffer(sstream);
+	}
+
+	/* Stream is finished; shutdown the SSL write direction once our buffer
+	   is empty. */
+	if (stream->finished && !sstream->shutdown && ret >= 0 &&
+	    (sstream->buffer == NULL || sstream->buffer->used == 0)) {
+		sstream->shutdown = TRUE;
+		if (SSL_shutdown(ssl_io->ssl) < 0) {
+			io_stream_set_error(
+				&sstream->ostream.iostream, "%s",
+				t_strdup_printf("SSL_shutdown() failed: %s",
+						openssl_iostream_error()));
+			sstream->ostream.ostream.stream_errno = EIO;
+			ret = -1;
+		}
+	}
+
+	if (ret == 0 && ssl_io->want_read) {
+		/* we need to read more data until we can continue. */
+		o_stream_set_flush_pending(plain_output, FALSE);
+		ssl_io->ostream_flush_waiting_input = TRUE;
+		ret = 1;
+	}
+
+	if (ret <= 0)
+		return ret;
+
+	/* return 1 only when the output buffer is empty, which is what the
+	   caller expects. */
+	return o_stream_get_buffer_used_size(plain_output) == 0 ? 1 : 0;
+}
+
+static ssize_t
+o_stream_ssl_sendv(struct ostream_private *stream,
+		   const struct const_iovec *iov, unsigned int iov_count)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)stream;
+	size_t bytes_sent = 0;
+
+	i_assert(!sstream->shutdown);
+
+	bytes_sent = o_stream_ssl_buffer(sstream, iov, iov_count, bytes_sent);
+	if (sstream->ssl_io->handshaked &&
+	    sstream->buffer->used == bytes_sent) {
+		/* buffer was empty before calling this. try to write it
+		   immediately. */
+		if (o_stream_ssl_flush_buffer(sstream) < 0)
+			return -1;
+	}
+	return bytes_sent;
+}
+
+static void o_stream_ssl_switch_ioloop_to(struct ostream_private *stream,
+					  struct ioloop *ioloop)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)stream;
+
+	o_stream_switch_ioloop_to(sstream->ssl_io->plain_output, ioloop);
+}
+
+static int plain_flush_callback(struct ssl_ostream *sstream)
+{
+	struct ostream *ostream = &sstream->ostream.ostream;
+	int ret, ret2;
+
+	/* try to actually flush the pending data */
+	if ((ret = o_stream_flush(sstream->ssl_io->plain_output)) < 0)
+		return -1;
+
+	/* we may be able to copy more data, try it */
+	o_stream_ref(ostream);
+	if (sstream->ostream.callback != NULL)
+		ret2 = sstream->ostream.callback(sstream->ostream.context);
+	else
+		ret2 = o_stream_flush(&sstream->ostream.ostream);
+	if (ret2 == 0)
+		o_stream_set_flush_pending(sstream->ssl_io->plain_output, TRUE);
+	o_stream_unref(&ostream);
+	if (ret2 < 0)
+		return -1;
+	return ret > 0 && ret2 > 0 ? 1 : 0;
+}
+
+static size_t
+o_stream_ssl_get_buffer_used_size(const struct ostream_private *stream)
+{
+	const struct ssl_ostream *sstream = (const struct ssl_ostream *)stream;
+	BIO *bio = SSL_get_wbio(sstream->ssl_io->ssl);
+	size_t wbuf_avail = BIO_ctrl_get_write_guarantee(bio);
+	size_t wbuf_total_size = BIO_get_write_buf_size(bio, 0);
+	size_t buffer_used = (sstream->buffer == NULL ? 0 :
+			      sstream->buffer->used);
+	i_assert(wbuf_avail <= wbuf_total_size);
+	return buffer_used + (wbuf_total_size - wbuf_avail) +
+		o_stream_get_buffer_used_size(sstream->ssl_io->plain_output);
+}
+
+static size_t
+o_stream_ssl_get_buffer_avail_size(const struct ostream_private *stream)
+{
+	const struct ssl_ostream *sstream = (const struct ssl_ostream *)stream;
+
+	return get_buffer_avail_size(sstream);
+}
+
+static void
+o_stream_ssl_flush_pending(struct ostream_private *_stream, bool set)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)_stream;
+
+	o_stream_set_flush_pending(sstream->ssl_io->plain_output, set);
+}
+
+static void o_stream_ssl_set_max_buffer_size(struct iostream_private *_stream,
+					     size_t max_size)
+{
+	struct ssl_ostream *sstream = (struct ssl_ostream *)_stream;
+
+	sstream->ostream.max_buffer_size = max_size;
+	o_stream_set_max_buffer_size(sstream->ssl_io->plain_output, max_size);
+}
+
+struct ostream *openssl_o_stream_create_ssl(struct ssl_iostream *ssl_io)
+{
+	struct ssl_ostream *sstream;
+
+	ssl_io->refcount++;
+
+	/* When ostream is destroyed, it's flushed. With iostream-ssl the
+	   flushing requires both istream and ostream to be available. The
+	   istream is referenced here to make sure it's not destroyed before
+	   the ostream. */
+	i_assert(ssl_io->ssl_input != NULL);
+	i_stream_ref(ssl_io->ssl_input);
+
+	sstream = i_new(struct ssl_ostream, 1);
+	sstream->ssl_io = ssl_io;
+	sstream->ostream.max_buffer_size =
+		ssl_io->plain_output->real_stream->max_buffer_size;
+	sstream->ostream.iostream.close = o_stream_ssl_close;
+	sstream->ostream.iostream.destroy = o_stream_ssl_destroy;
+	sstream->ostream.sendv = o_stream_ssl_sendv;
+	sstream->ostream.flush = o_stream_ssl_flush;
+	sstream->ostream.switch_ioloop_to = o_stream_ssl_switch_ioloop_to;
+
+	sstream->ostream.get_buffer_used_size =
+		o_stream_ssl_get_buffer_used_size;
+	sstream->ostream.get_buffer_avail_size =
+		o_stream_ssl_get_buffer_avail_size;
+	sstream->ostream.flush_pending = o_stream_ssl_flush_pending;
+	sstream->ostream.iostream.set_max_buffer_size =
+		o_stream_ssl_set_max_buffer_size;
+
+	sstream->ostream.callback = ssl_io->plain_output->real_stream->callback;
+	sstream->ostream.context = ssl_io->plain_output->real_stream->context;
+	o_stream_set_flush_callback(ssl_io->plain_output,
+				    plain_flush_callback, sstream);
+
+	return o_stream_create(&sstream->ostream, NULL,
+			       o_stream_get_fd(ssl_io->plain_output));
+}