+ Ssh ssh = c->ssh;
+ c->localid = alloc_channel_id(ssh);
+ c->closes = 0;
+ c->pending_eof = FALSE;
+ c->throttling_conn = FALSE;
+ c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
+ conf_get_int(ssh->conf, CONF_ssh_simple) ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
+ c->v.v2.chanreq_head = NULL;
+ c->v.v2.throttle_state = UNTHROTTLED;
+ bufchain_init(&c->v.v2.outbuffer);
+}
+
+/*
+ * Construct the common parts of a CHANNEL_OPEN.
+ */
+static struct Packet *ssh2_chanopen_init(struct ssh_channel *c, char *type)
+{
+ struct Packet *pktout;
+
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+ ssh2_pkt_addstring(pktout, type);
+ ssh2_pkt_adduint32(pktout, c->localid);
+ ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
+ ssh2_pkt_adduint32(pktout, OUR_V2_MAXPKT); /* our max pkt size */
+ return pktout;
+}
+
+/*
+ * CHANNEL_FAILURE doesn't come with any indication of what message
+ * caused it, so we have to keep track of the outstanding
+ * CHANNEL_REQUESTs ourselves.
+ */
+static void ssh2_queue_chanreq_handler(struct ssh_channel *c,
+ cchandler_fn_t handler, void *ctx)
+{
+ struct outstanding_channel_request *ocr =
+ snew(struct outstanding_channel_request);
+
+ assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+ ocr->handler = handler;
+ ocr->ctx = ctx;
+ ocr->next = NULL;
+ if (!c->v.v2.chanreq_head)
+ c->v.v2.chanreq_head = ocr;
+ else
+ c->v.v2.chanreq_tail->next = ocr;
+ c->v.v2.chanreq_tail = ocr;
+}
+
+/*
+ * Construct the common parts of a CHANNEL_REQUEST. If handler is not
+ * NULL then a reply will be requested and the handler will be called
+ * when it arrives. The returned packet is ready to have any
+ * request-specific data added and be sent. Note that if a handler is
+ * provided, it's essential that the request actually be sent.
+ *
+ * The handler will usually be passed the response packet in pktin.
+ * If pktin is NULL, this means that no reply will ever be forthcoming
+ * (e.g. because the entire connection is being destroyed) and the
+ * handler should free any storage it's holding.
+ */
+static struct Packet *ssh2_chanreq_init(struct ssh_channel *c, char *type,
+ cchandler_fn_t handler, void *ctx)
+{
+ struct Packet *pktout;
+
+ assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_addstring(pktout, type);
+ ssh2_pkt_addbool(pktout, handler != NULL);
+ if (handler != NULL)
+ ssh2_queue_chanreq_handler(c, handler, ctx);
+ return pktout;
+}
+
+/*
+ * Potentially enlarge the window on an SSH-2 channel.
+ */
+static void ssh2_handle_winadj_response(struct ssh_channel *, struct Packet *,
+ void *);
+static void ssh2_set_window(struct ssh_channel *c, int newwin)
+{
+ Ssh ssh = c->ssh;
+
+ /*
+ * Never send WINDOW_ADJUST for a channel that the remote side has
+ * already sent EOF on; there's no point, since it won't be
+ * sending any more data anyway. Ditto if _we've_ already sent
+ * CLOSE.
+ */
+ if (c->closes & (CLOSES_RCVD_EOF | CLOSES_SENT_CLOSE))
+ return;
+
+ /*
+ * If the remote end has a habit of ignoring maxpkt, limit the
+ * window so that it has no choice (assuming it doesn't ignore the
+ * window as well).
+ */
+ if ((ssh->remote_bugs & BUG_SSH2_MAXPKT) && newwin > OUR_V2_MAXPKT)
+ newwin = OUR_V2_MAXPKT;
+
+ /*
+ * Only send a WINDOW_ADJUST if there's significantly more window
+ * available than the other end thinks there is. This saves us
+ * sending a WINDOW_ADJUST for every character in a shell session.
+ *
+ * "Significant" is arbitrarily defined as half the window size.
+ */
+ if (newwin / 2 >= c->v.v2.locwindow) {
+ struct Packet *pktout;
+ unsigned *up;
+
+ /*
+ * In order to keep track of how much window the client
+ * actually has available, we'd like it to acknowledge each
+ * WINDOW_ADJUST. We can't do that directly, so we accompany
+ * it with a CHANNEL_REQUEST that has to be acknowledged.
+ *
+ * This is only necessary if we're opening the window wide.
+ * If we're not, then throughput is being constrained by
+ * something other than the maximum window size anyway.
+ */
+ if (newwin == c->v.v2.locmaxwin &&
+ !(ssh->remote_bugs & BUG_CHOKES_ON_WINADJ)) {
+ up = snew(unsigned);
+ *up = newwin - c->v.v2.locwindow;
+ pktout = ssh2_chanreq_init(c, "winadj@putty.projects.tartarus.org",
+ ssh2_handle_winadj_response, up);
+ ssh2_pkt_send(ssh, pktout);
+
+ if (c->v.v2.throttle_state != UNTHROTTLED)
+ c->v.v2.throttle_state = UNTHROTTLING;
+ } else {
+ /* Pretend the WINDOW_ADJUST was acked immediately. */
+ c->v.v2.remlocwin = newwin;
+ c->v.v2.throttle_state = THROTTLED;
+ }
+ pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+ ssh2_pkt_adduint32(pktout, c->remoteid);
+ ssh2_pkt_adduint32(pktout, newwin - c->v.v2.locwindow);
+ ssh2_pkt_send(ssh, pktout);
+ c->v.v2.locwindow = newwin;
+ }
+}
+
+/*
+ * Find the channel associated with a message. If there's no channel,
+ * or it's not properly open, make a noise about it and return NULL.
+ */
+static struct ssh_channel *ssh2_channel_msg(Ssh ssh, struct Packet *pktin)
+{
+ unsigned localid = ssh_pkt_getuint32(pktin);
+ struct ssh_channel *c;
+
+ c = find234(ssh->channels, &localid, ssh_channelfind);
+ if (!c ||
+ (c->halfopen && pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION &&
+ pktin->type != SSH2_MSG_CHANNEL_OPEN_FAILURE)) {
+ char *buf = dupprintf("Received %s for %s channel %u",
+ ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
+ pktin->type),
+ c ? "half-open" : "nonexistent", localid);
+ ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+ sfree(buf);
+ return NULL;
+ }
+ return c;
+}
+
+static void ssh2_handle_winadj_response(struct ssh_channel *c,
+ struct Packet *pktin, void *ctx)
+{
+ unsigned *sizep = ctx;
+
+ /*
+ * Winadj responses should always be failures. However, at least
+ * one server ("boks_sshd") is known to return SUCCESS for channel
+ * requests it's never heard of, such as "winadj@putty". Raised
+ * with foxt.com as bug 090916-090424, but for the sake of a quiet
+ * life, we don't worry about what kind of response we got.
+ */
+
+ c->v.v2.remlocwin += *sizep;
+ sfree(sizep);
+ /*
+ * winadj messages are only sent when the window is fully open, so
+ * if we get an ack of one, we know any pending unthrottle is
+ * complete.
+ */
+ if (c->v.v2.throttle_state == UNTHROTTLING)
+ c->v.v2.throttle_state = UNTHROTTLED;
+}
+
+static void ssh2_msg_channel_response(Ssh ssh, struct Packet *pktin)
+{
+ struct ssh_channel *c = ssh2_channel_msg(ssh, pktin);
+ struct outstanding_channel_request *ocr;
+
+ if (!c) return;
+ ocr = c->v.v2.chanreq_head;
+ if (!ocr) {
+ ssh2_msg_unexpected(ssh, pktin);
+ return;
+ }
+ ocr->handler(c, pktin, ocr->ctx);
+ c->v.v2.chanreq_head = ocr->next;
+ sfree(ocr);
+ /*
+ * We may now initiate channel-closing procedures, if that
+ * CHANNEL_REQUEST was the last thing outstanding before we send
+ * CHANNEL_CLOSE.
+ */
+ ssh2_channel_check_close(c);
+}
+
+static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
+{
+ struct ssh_channel *c;
+ c = ssh2_channel_msg(ssh, pktin);
+ if (!c)
+ return;
+ if (!(c->closes & CLOSES_SENT_EOF)) {
+ c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
+ ssh2_try_send_and_unthrottle(ssh, c);
+ }