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-rw-r--r--src/lib/istream-multiplex.c298
1 files changed, 298 insertions, 0 deletions
diff --git a/src/lib/istream-multiplex.c b/src/lib/istream-multiplex.c
new file mode 100644
index 0000000..c70d0cc
--- /dev/null
+++ b/src/lib/istream-multiplex.c
@@ -0,0 +1,298 @@
+/* Copyright (c) 2017-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "ioloop.h"
+#include "array.h"
+#include "istream-private.h"
+#include "istream-multiplex.h"
+
+/* all multiplex packets are [1 byte cid][4 byte length][data] */
+
+struct multiplex_istream;
+
+struct multiplex_ichannel {
+ struct istream_private istream;
+ struct multiplex_istream *mstream;
+ uint8_t cid;
+ size_t pending_pos;
+ bool closed:1;
+};
+
+struct multiplex_istream {
+ struct istream *parent;
+
+ /* channel 0 is main channel */
+ uint8_t cur_channel;
+ unsigned int remain;
+ size_t bufsize;
+ ARRAY(struct multiplex_ichannel *) channels;
+
+ bool blocking:1;
+};
+
+static ssize_t i_stream_multiplex_ichannel_read(struct istream_private *stream);
+
+static struct multiplex_ichannel *
+get_channel(struct multiplex_istream *mstream, uint8_t cid)
+{
+ struct multiplex_ichannel *channel;
+ i_assert(mstream != NULL);
+ array_foreach_elem(&mstream->channels, channel) {
+ if (channel != NULL && channel->cid == cid)
+ return channel;
+ }
+ return NULL;
+}
+
+static void propagate_error(struct multiplex_istream *mstream, int stream_errno)
+{
+ struct multiplex_ichannel *channel;
+ array_foreach_elem(&mstream->channels, channel)
+ if (channel != NULL)
+ channel->istream.istream.stream_errno = stream_errno;
+}
+
+static void propagate_eof(struct multiplex_istream *mstream)
+{
+ struct multiplex_ichannel *channel;
+ array_foreach_elem(&mstream->channels, channel) {
+ if (channel == NULL)
+ continue;
+
+ channel->istream.istream.eof = TRUE;
+ if (mstream->remain > 0) {
+ channel->istream.istream.stream_errno = EPIPE;
+ io_stream_set_error(&channel->istream.iostream,
+ "Unexpected EOF - %u bytes remaining in packet",
+ mstream->remain);
+ }
+ }
+}
+
+static ssize_t
+i_stream_multiplex_read(struct multiplex_istream *mstream,
+ struct multiplex_ichannel *req_channel)
+{
+ const unsigned char *data;
+ size_t len = 0, used, wanted, avail;
+ ssize_t ret, got = 0;
+
+ if (mstream->parent == NULL) {
+ req_channel->istream.istream.eof = TRUE;
+ return -1;
+ }
+
+ (void)i_stream_get_data(mstream->parent, &len);
+
+ if (len == 0 && mstream->parent->closed) {
+ req_channel->istream.istream.eof = TRUE;
+ return -1;
+ }
+
+ if (((mstream->remain > 0 && len == 0) ||
+ (mstream->remain == 0 && len < 5)) &&
+ (ret = i_stream_read_memarea(mstream->parent)) <= 0) {
+ propagate_error(mstream, mstream->parent->stream_errno);
+ if (mstream->parent->eof)
+ propagate_eof(mstream);
+ return ret;
+ }
+
+ for(;;) {
+ data = i_stream_get_data(mstream->parent, &len);
+ if (len == 0) {
+ if (got == 0 && mstream->blocking) {
+ /* can't return 0 with blocking istreams,
+ so try again from the beginning. */
+ return i_stream_multiplex_read(mstream, req_channel);
+ }
+ break;
+ }
+
+ if (mstream->remain > 0) {
+ struct multiplex_ichannel *channel =
+ get_channel(mstream, mstream->cur_channel);
+ wanted = I_MIN(len, mstream->remain);
+ /* is it open? */
+ if (channel != NULL && !channel->closed) {
+ struct istream_private *stream = &channel->istream;
+ stream->pos += channel->pending_pos;
+ bool alloc_ret = i_stream_try_alloc(stream, wanted, &avail);
+ stream->pos -= channel->pending_pos;
+ if (!alloc_ret) {
+ i_stream_set_input_pending(&stream->istream, TRUE);
+ if (channel->cid != req_channel->cid)
+ return 0;
+ if (got > 0)
+ break;
+ return -2;
+ }
+
+ used = I_MIN(wanted, avail);
+
+ /* dump into buffer */
+ if (channel->cid != req_channel->cid) {
+ i_assert(stream->pos + channel->pending_pos + used <= stream->buffer_size);
+ memcpy(stream->w_buffer + stream->pos + channel->pending_pos,
+ data, used);
+ channel->pending_pos += used;
+ i_stream_set_input_pending(&stream->istream, TRUE);
+ } else {
+ i_assert(stream->pos + used <= stream->buffer_size);
+ memcpy(stream->w_buffer + stream->pos, data, used);
+ stream->pos += used;
+ got += used;
+ }
+ } else {
+ used = wanted;
+ }
+ mstream->remain -= used;
+ i_stream_skip(mstream->parent, used);
+ /* see if there is more to read */
+ continue;
+ }
+ if (mstream->remain == 0) {
+ /* need more data */
+ if (len < 5) {
+ ret = i_stream_multiplex_ichannel_read(&req_channel->istream);
+ if (ret > 0)
+ got += ret;
+ break;
+ }
+ /* channel ID */
+ mstream->cur_channel = data[0];
+ /* data length */
+ mstream->remain = be32_to_cpu_unaligned(data+1);
+ i_stream_skip(mstream->parent, 5);
+ }
+ }
+
+ propagate_error(mstream, mstream->parent->stream_errno);
+ if (mstream->parent->eof)
+ propagate_eof(mstream);
+
+ return got;
+}
+
+static ssize_t i_stream_multiplex_ichannel_read(struct istream_private *stream)
+{
+ struct multiplex_ichannel *channel =
+ container_of(stream, struct multiplex_ichannel, istream);
+ /* if previous multiplex read dumped data for us
+ actually serve it here. */
+ if (channel->pending_pos > 0) {
+ ssize_t ret = channel->pending_pos;
+ stream->pos += channel->pending_pos;
+ channel->pending_pos = 0;
+ return ret;
+ }
+ return i_stream_multiplex_read(channel->mstream, channel);
+}
+
+static void
+i_stream_multiplex_ichannel_switch_ioloop_to(struct istream_private *stream,
+ struct ioloop *ioloop)
+{
+ struct multiplex_ichannel *channel =
+ container_of(stream, struct multiplex_ichannel, istream);
+
+ i_stream_switch_ioloop_to(channel->mstream->parent, ioloop);
+}
+
+static void
+i_stream_multiplex_ichannel_close(struct iostream_private *stream, bool close_parent)
+{
+ struct multiplex_ichannel *arr_channel;
+ struct multiplex_ichannel *channel =
+ container_of(stream, struct multiplex_ichannel,
+ istream.iostream);
+ channel->closed = TRUE;
+ if (close_parent) {
+ array_foreach_elem(&channel->mstream->channels, arr_channel)
+ if (arr_channel != NULL && !arr_channel->closed)
+ return;
+ i_stream_close(channel->mstream->parent);
+ }
+}
+
+static void i_stream_multiplex_try_destroy(struct multiplex_istream *mstream)
+{
+ struct multiplex_ichannel *channel;
+ /* can't do anything until they are all closed */
+ array_foreach_elem(&mstream->channels, channel)
+ if (channel != NULL)
+ return;
+ i_stream_unref(&mstream->parent);
+ array_free(&mstream->channels);
+ i_free(mstream);
+}
+
+static void i_stream_multiplex_ichannel_destroy(struct iostream_private *stream)
+{
+ struct multiplex_ichannel **channelp;
+ struct multiplex_ichannel *channel =
+ container_of(stream, struct multiplex_ichannel,
+ istream.iostream);
+ i_stream_multiplex_ichannel_close(stream, TRUE);
+ i_stream_free_buffer(&channel->istream);
+ array_foreach_modifiable(&channel->mstream->channels, channelp) {
+ if (*channelp == channel) {
+ *channelp = NULL;
+ break;
+ }
+ }
+ i_stream_multiplex_try_destroy(channel->mstream);
+}
+
+static struct istream *
+i_stream_add_channel_real(struct multiplex_istream *mstream, uint8_t cid)
+{
+ struct multiplex_ichannel *channel = i_new(struct multiplex_ichannel, 1);
+ channel->cid = cid;
+ channel->mstream = mstream;
+ channel->istream.read = i_stream_multiplex_ichannel_read;
+ channel->istream.switch_ioloop_to = i_stream_multiplex_ichannel_switch_ioloop_to;
+ channel->istream.iostream.close = i_stream_multiplex_ichannel_close;
+ channel->istream.iostream.destroy = i_stream_multiplex_ichannel_destroy;
+ channel->istream.max_buffer_size = mstream->bufsize;
+ channel->istream.istream.blocking = mstream->blocking;
+ if (cid == 0)
+ channel->istream.fd = i_stream_get_fd(mstream->parent);
+ else
+ channel->istream.fd = -1;
+ array_push_back(&channel->mstream->channels, &channel);
+
+ return i_stream_create(&channel->istream, NULL, channel->istream.fd, 0);
+}
+
+struct istream *i_stream_multiplex_add_channel(struct istream *stream, uint8_t cid)
+{
+ struct multiplex_ichannel *chan =
+ container_of(stream->real_stream,
+ struct multiplex_ichannel, istream);
+ i_assert(get_channel(chan->mstream, cid) == NULL);
+
+ return i_stream_add_channel_real(chan->mstream, cid);
+}
+
+struct istream *i_stream_create_multiplex(struct istream *parent, size_t bufsize)
+{
+ struct multiplex_istream *mstream;
+
+ mstream = i_new(struct multiplex_istream, 1);
+ mstream->parent = parent;
+ mstream->bufsize = bufsize;
+ mstream->blocking = parent->blocking;
+ i_array_init(&mstream->channels, 8);
+ i_stream_ref(parent);
+
+ return i_stream_add_channel_real(mstream, 0);
+}
+
+uint8_t i_stream_multiplex_get_channel_id(struct istream *stream)
+{
+ struct multiplex_ichannel *channel =
+ container_of(stream->real_stream,
+ struct multiplex_ichannel, istream);
+ return channel->cid;
+}