Crank version number. Remove BufferLimit option.

The HPNBufferLimit option was intended to clamp the inbound
flow control buffer to half of the available window. Unfortunately,
it looks like it's been broken for some time with a tendancy
to reduce the window to zero and cut the connection.

As this option was specifically to deal with one special case and
it's broken, fixing it doesn't seem like the right thing to do.

Author: rapier1

channels.c

@@ -2408,40 +2408,20 @@ channel_check_window(struct ssh *ssh, Channel *c)
 {
 	int r;
 
-	/* going back to a set denominator of 2. Prior versions had a
-	 * dynamic denominator based on the size of the buffer. This may
-	 * have been helpful in some situations but it isn't helping in
-	 * the general case -cjr 6/30/23 */
 	if (c->type == SSH_CHANNEL_OPEN &&
 	    !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 	    ((c->local_window_max - c->local_window > c->local_maxpacket*3) ||
 	    c->local_window < c->local_window_max/2) &&
 	    c->local_consumed > 0) {
-		u_int addition = 0;
+		int addition = 0;
 		u_int32_t tcpwinsz = channel_tcpwinsz(ssh);
 		/* adjust max window size if we are in a dynamic environment
 		 * and the tcp receive buffer is larger than the ssh window */
 		if (c->dynamic_window && (tcpwinsz > c->local_window_max)) {
-			if (c->hpn_buffer_limit) {
-				/* limit window growth to prevent buffer issues
-				 * still not sure what is causing the buffer issues
-				 * but it may be an issue with c->local_consumed not being
-				 * handled properly in the cases of bottenecked IO to the
-				 * wfd endpoint. This does have an impact on throughput
-				 * as we're essentially maxing out local_window_max to
-				 * half of the window size */
-				addition = (tcpwinsz/2 - c->local_window_max);
-			}
-			else {
-				/* aggressively grow the window */
-				addition = tcpwinsz - c->local_window_max;
-			}
+			/* aggressively grow the window */
+			addition = tcpwinsz - c->local_window_max;
 			c->local_window_max += addition;
-			/* doesn't look like we need these
-			 * sshbuf_set_window_max(c->output, c->local_window_max);
-			 * sshbuf_set_window_max(c->input, c->local_window_max);
-			 */
-			debug("Channel %d: Window growth to %d by %d bytes",c->self,
+			debug_f("Channel %d: Window growth to %d by %d bytes",c->self,
 			      c->local_window_max, addition);
 		}
 		if (!c->have_remote_id)

channels.h

@@ -175,7 +175,6 @@ struct Channel {
 	u_int	local_consumed;
 	u_int	local_maxpacket;
 	int	dynamic_window;
-	int     hpn_buffer_limit;
 	int     extended_usage;
 	int	single_connection;
 	/* u_int	tcpwinsz; */

clientloop.c

@@ -2911,11 +2911,6 @@ client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
 	if ((c = channel_lookup(ssh, id)) == NULL)
 		fatal_f("channel %d: unknown channel", id);
 
-	if (options.hpn_buffer_limit) {
-		debug_f("Limiting receive buffer size");
-		c->hpn_buffer_limit = 1;
-	}
-
 	ssh_packet_set_interactive(ssh, want_tty,
 	    options.ip_qos_interactive, options.ip_qos_bulk);
 

hpnssh.1

@@ -555,7 +555,6 @@ For full details of the options listed below, and their possible values, see
 .It HostKeyAlias
 .It Hostname
 .It HPNDisabled*
-.It HPNBufferLimit*
 .It IdentitiesOnly
 .It IdentityAgent
 .It IdentityFile

hpnssh_config.5

@@ -1081,15 +1081,6 @@ In some situations, such as transfers on a local area network, the impact
 of the HPN code produces a net decrease in performance. In these cases it is
 helpful to disable the HPN functionality. By default HPNDisabled is set to 
 .Cm no. HPNSSH only.
-.It Cm HPNBufferLimit
-This option will force the hpnssh receive buffer to grow more slowly and limits
-the growth to one half of the TCP receive buffer. This option can prove useful
-in situation where a high speed path with larger RTTs are writing to a slower
-device or file system. Enabling this option will reduce performance but may provide
-a more stable connection. The option only impacts the receiving side of the connection. 
-For example, a client receiving data from a server but not a client sending data.
-By default this option is set to 
-.Cm no. HPNSSH only.
 .It Cm IdentitiesOnly
 Specifies that
 .Xr ssh 1

hpnsshd_config.5

@@ -890,16 +890,6 @@ In some situations, such as transfers on a local area network, the impact
 of the HPN code produces a net decrease in performance. In these cases it is
 helpful to disable the HPN functionality. By default HPNDisabled is set to 
 .CM no.
-.It Cm HPNBufferLimit
-This option will force the hpnssh receive buffer to grow more slowly and limits
-the growth to one half of the TCP receive buffer. This option can prove useful
-in situation where a high speed path with larger RTTs are writing to a slower
-device or file system. Enabling this option will reduce performance but may provide
-a more stable connection. The option only impacts the receiving side of the connection. 
-For example, a client receiving data from a server but not a client sending data. If 
-enabled on a server this will impact all incoming connections. 
-By default this option is set to 
-.Cm no. HPNSSH only.
 .It Cm IgnoreRhosts
 Specifies whether to ignore per-user
 .Pa .rhosts

packet.h

@@ -97,9 +97,6 @@ struct ssh {
 
 	/* track if we have disabled the mac as well */
 	int none_mac;
-
-	/* use the less agressive window growth option */
-	int hpn_buffer_limit;
 };
 
 typedef int (ssh_packet_hook_fn)(struct ssh *, struct sshbuf *,

readconf.c

@@ -171,7 +171,7 @@ typedef enum {
 	oTunnel, oTunnelDevice,
 	oLocalCommand, oPermitLocalCommand, oRemoteCommand,
 	oTcpRcvBufPoll, oHPNDisabled,
-	oNoneEnabled, oNoneMacEnabled, oNoneSwitch, oHPNBufferLimit,
+	oNoneEnabled, oNoneMacEnabled, oNoneSwitch,
 	oMetrics, oMetricsPath, oMetricsInterval, oFallback, oFallbackPort,
 	oVisualHostKey,
 	oKexAlgorithms, oIPQoS, oRequestTTY, oSessionType, oStdinNull,
@@ -310,7 +310,6 @@ static struct {
 	{ "noneenabled", oNoneEnabled },
 	{ "nonemacenabled", oNoneMacEnabled },
 	{ "noneswitch", oNoneSwitch },
-	{ "hpnbufferlimit", oHPNBufferLimit },
 	{ "metrics", oMetrics },
 	{ "metricspath", oMetricsPath },
 	{ "metricsinterval", oMetricsInterval },
@@ -1270,10 +1269,6 @@ process_config_line_depth(Options *options, struct passwd *pw, const char *host,
 		intptr = &options->nonemac_enabled;
 		goto parse_flag;
 
-	case oHPNBufferLimit:
-		intptr = &options->hpn_buffer_limit;
-		goto parse_flag;
-
 	case oMetrics:
 		intptr = &options->metrics;
 		goto parse_flag;
@@ -2701,7 +2696,6 @@ initialize_options(Options * options)
 	options->metrics_path = NULL;
 	options->metrics_interval = -1;
 	options->hpn_disabled = -1;
-	options->hpn_buffer_limit = -1;
 	options->fallback = -1;
 	options->fallback_port = -1;
 	options->tcp_rcv_buf_poll = -1;
@@ -2880,8 +2874,6 @@ fill_default_options(Options * options)
 		options->server_alive_count_max = 3;
 	if (options->hpn_disabled == -1)
 		options->hpn_disabled = 0;
-	if (options->hpn_buffer_limit == -1)
-		options->hpn_buffer_limit = 0;
 	if (options->tcp_rcv_buf_poll == -1)
 		options->tcp_rcv_buf_poll = 1;
 	if (options->none_switch == -1)

readconf.h

@@ -52,7 +52,6 @@ typedef struct {
 	int     tcp_keep_alive;	/* Set SO_KEEPALIVE. */
 	int     tcp_rcv_buf_poll; /* Option to poll recv buf every window transfer */
 	int     hpn_disabled;     /* Switch to disable HPN buffer management */
-	int     hpn_buffer_limit; /* limit local_window_max to 1/2 receive buffer */
 	int	ip_qos_interactive;	/* IP ToS/DSCP/class for interactive */
 	int	ip_qos_bulk;		/* IP ToS/DSCP/class for bulk traffic */
 	SyslogFacility log_facility;	/* Facility for system logging. */

servconf.c

@@ -192,7 +192,6 @@ initialize_server_options(ServerOptions *options)
 	options->hpn_disabled = -1;
 	options->none_enabled = -1;
 	options->nonemac_enabled = -1;
-	options->hpn_buffer_limit = -1;
 	options->ip_qos_interactive = -1;
 	options->ip_qos_bulk = -1;
 	options->version_addendum = NULL;
@@ -441,8 +440,6 @@ fill_default_server_options(ServerOptions *options)
 	}
 	if (options->hpn_disabled == -1)
 		options->hpn_disabled = 0;
-	if (options->hpn_buffer_limit == -1)
-		options->hpn_buffer_limit = 0;
 	if (options->ip_qos_interactive == -1)
 		options->ip_qos_interactive = IPTOS_DSCP_AF21;
 	if (options->ip_qos_bulk == -1)
@@ -524,8 +521,7 @@ typedef enum {
 	sKerberosGetAFSToken, sPasswordAuthentication,
 	sKbdInteractiveAuthentication, sListenAddress, sAddressFamily,
 	sPrintMotd, sPrintLastLog, sIgnoreRhosts,
-	sNoneEnabled, sNoneMacEnabled, sHPNBufferLimit,
-	sTcpRcvBufPoll, sHPNDisabled,
+	sNoneEnabled, sNoneMacEnabled, sTcpRcvBufPoll, sHPNDisabled,
 	sX11Forwarding, sX11DisplayOffset, sX11UseLocalhost,
 	sPermitTTY, sStrictModes, sEmptyPasswd, sTCPKeepAlive,
 	sPermitUserEnvironment, sAllowTcpForwarding, sCompression,
@@ -696,7 +692,6 @@ static struct {
 	{ "tcprcvbufpoll", sTcpRcvBufPoll, SSHCFG_ALL },
 	{ "noneenabled", sNoneEnabled, SSHCFG_ALL },
 	{ "nonemacenabled", sNoneMacEnabled, SSHCFG_ALL },
-	{ "hpnbufferlimit", sHPNBufferLimit, SSHCFG_ALL },
 	{ "kexalgorithms", sKexAlgorithms, SSHCFG_GLOBAL },
 	{ "include", sInclude, SSHCFG_ALL },
 	{ "ipqos", sIPQoS, SSHCFG_ALL },
@@ -1576,10 +1571,6 @@ process_server_config_line_depth(ServerOptions *options, char *line,
 		intptr = &options->nonemac_enabled;
 		goto parse_flag;
 
-	case sHPNBufferLimit:
-		intptr = &options->hpn_buffer_limit;
-		goto parse_flag;		
-		
 	case sHostbasedAuthentication:
 		intptr = &options->hostbased_authentication;
 		goto parse_flag;