+/*
+ * 'channel_pre*' are called just before select() to add any bits relevant to
+ * channels in the select bitmasks.
+ */
+/*
+ * 'channel_post*': perform any appropriate operations for channels which
+ * have events pending.
+ */
+typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
+chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
+chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
+
+void
+channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ FD_SET(c->sock, readset);
+}
+
+void
+channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ debug3("channel %d: waiting for connection", c->self);
+ FD_SET(c->sock, writeset);
+}
+
+void
+channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ if (buffer_len(&c->input) < packet_get_maxsize())
+ FD_SET(c->sock, readset);
+ if (buffer_len(&c->output) > 0)
+ FD_SET(c->sock, writeset);
+}
+
+void
+channel_pre_open_15(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ /* test whether sockets are 'alive' for read/write */
+ if (c->istate == CHAN_INPUT_OPEN)
+ if (buffer_len(&c->input) < packet_get_maxsize())
+ FD_SET(c->sock, readset);
+ if (c->ostate == CHAN_OUTPUT_OPEN ||
+ c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+ if (buffer_len(&c->output) > 0) {
+ FD_SET(c->sock, writeset);
+ } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+ chan_obuf_empty(c);
+ }
+ }
+}
+
+void
+channel_pre_open_20(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ if (c->istate == CHAN_INPUT_OPEN &&
+ c->remote_window > 0 &&
+ buffer_len(&c->input) < c->remote_window)
+ FD_SET(c->rfd, readset);
+ if (c->ostate == CHAN_OUTPUT_OPEN ||
+ c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+ if (buffer_len(&c->output) > 0) {
+ FD_SET(c->wfd, writeset);
+ } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+ chan_obuf_empty(c);
+ }
+ }
+ /** XXX check close conditions, too */
+ if (c->efd != -1) {
+ if (c->extended_usage == CHAN_EXTENDED_WRITE &&
+ buffer_len(&c->extended) > 0)
+ FD_SET(c->efd, writeset);
+ else if (c->extended_usage == CHAN_EXTENDED_READ &&
+ buffer_len(&c->extended) < c->remote_window)
+ FD_SET(c->efd, readset);
+ }
+}
+
+void
+channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ if (buffer_len(&c->input) == 0) {
+ packet_start(SSH_MSG_CHANNEL_CLOSE);
+ packet_put_int(c->remote_id);
+ packet_send();
+ c->type = SSH_CHANNEL_CLOSED;
+ debug("channel %d: closing after input drain.", c->self);
+ }
+}
+
+void
+channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
+{
+ if (buffer_len(&c->output) == 0)
+ chan_mark_dead(c);
+ else
+ FD_SET(c->sock, writeset);
+}
+
+/*
+ * This is a special state for X11 authentication spoofing. An opened X11
+ * connection (when authentication spoofing is being done) remains in this
+ * state until the first packet has been completely read. The authentication
+ * data in that packet is then substituted by the real data if it matches the
+ * fake data, and the channel is put into normal mode.
+ * XXX All this happens at the client side.
+ * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
+ */
+int
+x11_open_helper(Buffer *b)
+{
+ u_char *ucp;
+ u_int proto_len, data_len;
+
+ /* Check if the fixed size part of the packet is in buffer. */
+ if (buffer_len(b) < 12)
+ return 0;
+
+ /* Parse the lengths of variable-length fields. */
+ ucp = (u_char *) buffer_ptr(b);
+ if (ucp[0] == 0x42) { /* Byte order MSB first. */
+ proto_len = 256 * ucp[6] + ucp[7];
+ data_len = 256 * ucp[8] + ucp[9];
+ } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
+ proto_len = ucp[6] + 256 * ucp[7];
+ data_len = ucp[8] + 256 * ucp[9];
+ } else {
+ debug("Initial X11 packet contains bad byte order byte: 0x%x",
+ ucp[0]);
+ return -1;
+ }
+
+ /* Check if the whole packet is in buffer. */
+ if (buffer_len(b) <
+ 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
+ return 0;
+
+ /* Check if authentication protocol matches. */
+ if (proto_len != strlen(x11_saved_proto) ||
+ memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
+ debug("X11 connection uses different authentication protocol.");
+ return -1;
+ }
+ /* Check if authentication data matches our fake data. */
+ if (data_len != x11_fake_data_len ||
+ memcmp(ucp + 12 + ((proto_len + 3) & ~3),
+ x11_fake_data, x11_fake_data_len) != 0) {
+ debug("X11 auth data does not match fake data.");
+ return -1;
+ }
+ /* Check fake data length */
+ if (x11_fake_data_len != x11_saved_data_len) {
+ error("X11 fake_data_len %d != saved_data_len %d",
+ x11_fake_data_len, x11_saved_data_len);
+ return -1;
+ }