From 1c8f00bd5978abe89d8b2410fa6d5c14d7bf7b46 Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Thu, 27 Jan 2022 14:34:10 +0800
Subject: [PATCH] Leave non-interactive at default QoS class

Lower class levels are less well defined, and non-interactive
SSH can carry various different types of applications.

This change also sets lowdelay class (AF21) earlier in an an outbound
dbclient session
---
 channel.h         | 10 ++--------
 cli-chansession.c |  8 ++------
 cli-main.c        |  5 +++--
 cli-session.c     |  3 +++
 cli-tcpfwd.c      |  7 +++----
 common-channel.c  | 13 +++----------
 common-session.c  | 18 ++++--------------
 netio.c           | 17 +++++++----------
 netio.h           |  8 ++++----
 svr-chansession.c |  5 +++--
 svr-tcpfwd.c      |  9 ++++-----
 tcp-accept.c      |  7 -------
 tcpfwd.h          |  1 -
 13 files changed, 38 insertions(+), 73 deletions(-)

diff --git a/channel.h b/channel.h
index 6e1e399..dd174aa 100644
--- a/channel.h
+++ b/channel.h
@@ -28,6 +28,7 @@
 #include "includes.h"
 #include "buffer.h"
 #include "circbuffer.h"
+#include "netio.h"
 
 #define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED    1
 #define SSH_OPEN_CONNECT_FAILED                 2
@@ -41,13 +42,6 @@
 
 struct ChanType;
 
-enum dropbear_channel_prio {
-	DROPBEAR_CHANNEL_PRIO_INTERACTIVE, /* pty shell, x11 */
-	DROPBEAR_CHANNEL_PRIO_UNKNOWABLE, /* tcp - can't know what's being forwarded */
-	DROPBEAR_CHANNEL_PRIO_BULK, /* the rest - probably scp, rsync, git, or something */
-	DROPBEAR_CHANNEL_PRIO_EARLY, /* channel is still being set up */
-};
-
 struct Channel {
 
 	unsigned int index; /* the local channel index */
@@ -88,7 +82,7 @@ struct Channel {
 
 	const struct ChanType* type;
 
-	enum dropbear_channel_prio prio;
+	enum dropbear_prio prio;
 };
 
 struct ChanType {
diff --git a/cli-chansession.c b/cli-chansession.c
index 14a2779..73bee17 100644
--- a/cli-chansession.c
+++ b/cli-chansession.c
@@ -348,7 +348,6 @@ static int cli_init_stdpipe_sess(struct Channel *channel) {
 }
 
 static int cli_init_netcat(struct Channel *channel) {
-	channel->prio = DROPBEAR_CHANNEL_PRIO_UNKNOWABLE;
 	return cli_init_stdpipe_sess(channel);
 }
 
@@ -361,12 +360,9 @@ static int cli_initchansess(struct Channel *channel) {
 		cli_setup_agent(channel);
 	}
 #endif
-
 	if (cli_opts.wantpty) {
 		send_chansess_pty_req(channel);
-		channel->prio = DROPBEAR_CHANNEL_PRIO_INTERACTIVE;
-	} else {
-		channel->prio = DROPBEAR_CHANNEL_PRIO_BULK;
+		channel->prio = DROPBEAR_PRIO_LOWDELAY;
 	}
 
 	send_chansess_shell_req(channel);
@@ -375,7 +371,7 @@ static int cli_initchansess(struct Channel *channel) {
 		cli_tty_setup();
 		channel->read_mangler = cli_escape_handler;
 		cli_ses.last_char = '\r';
-	}	
+	}
 
 	return 0; /* Success */
 }
diff --git a/cli-main.c b/cli-main.c
index 5d0b9cf..b571b90 100644
--- a/cli-main.c
+++ b/cli-main.c
@@ -84,8 +84,9 @@ int main(int argc, char ** argv) {
 	} else
 #endif
 	{
-		progress = connect_remote(cli_opts.remotehost, cli_opts.remoteport, 
-			cli_connected, &ses, cli_opts.bind_address, cli_opts.bind_port);
+		progress = connect_remote(cli_opts.remotehost, cli_opts.remoteport,
+			cli_connected, &ses, cli_opts.bind_address, cli_opts.bind_port,
+			DROPBEAR_PRIO_LOWDELAY);
 		sock_in = sock_out = -1;
 	}
 
diff --git a/cli-session.c b/cli-session.c
index 66352cc..2044b46 100644
--- a/cli-session.c
+++ b/cli-session.c
@@ -102,6 +102,9 @@ void cli_connected(int result, int sock, void* userdata, const char *errstring)
 		dropbear_exit("Connect failed: %s", errstring);
 	}
 	myses->sock_in = myses->sock_out = sock;
+	TRACE(("cli_connected"))
+	ses.socket_prio = DROPBEAR_PRIO_NORMAL;
+	/* switches to lowdelay */
 	update_channel_prio();
 }
 
diff --git a/cli-tcpfwd.c b/cli-tcpfwd.c
index e61a0c3..1b95615 100644
--- a/cli-tcpfwd.c
+++ b/cli-tcpfwd.c
@@ -51,7 +51,7 @@ static int cli_localtcp(const char* listenaddr,
 		unsigned int remoteport);
 static const struct ChanType cli_chan_tcplocal = {
 	"direct-tcpip",
-	tcp_prio_inithandler,
+	NULL,
 	NULL,
 	NULL,
 	NULL,
@@ -272,10 +272,9 @@ static int newtcpforwarded(struct Channel * channel) {
 		goto out;
 	}
 
-	channel->prio = DROPBEAR_CHANNEL_PRIO_UNKNOWABLE;
-
 	snprintf(portstring, sizeof(portstring), "%u", fwd->connectport);
-	channel->conn_pending = connect_remote(fwd->connectaddr, portstring, channel_connect_done, channel, NULL, NULL);
+	channel->conn_pending = connect_remote(fwd->connectaddr, portstring, channel_connect_done,
+		channel, NULL, NULL, DROPBEAR_PRIO_NORMAL);
 
 	err = SSH_OPEN_IN_PROGRESS;
 
diff --git a/common-channel.c b/common-channel.c
index 047eece..be5b57f 100644
--- a/common-channel.c
+++ b/common-channel.c
@@ -162,7 +162,7 @@ static struct Channel* newchannel(unsigned int remotechan,
 	newchan->recvdonelen = 0;
 	newchan->recvmaxpacket = RECV_MAX_CHANNEL_DATA_LEN;
 
-	newchan->prio = DROPBEAR_CHANNEL_PRIO_EARLY; /* inithandler sets it */
+	newchan->prio = DROPBEAR_PRIO_NORMAL;
 
 	ses.channels[i] = newchan;
 	ses.chancount++;
@@ -955,9 +955,7 @@ void recv_msg_channel_open() {
 		}
 	}
 
-	if (channel->prio == DROPBEAR_CHANNEL_PRIO_EARLY) {
-		channel->prio = DROPBEAR_CHANNEL_PRIO_BULK;
-	}
+	update_channel_prio();
 
 	/* success */
 	send_msg_channel_open_confirmation(channel, channel->recvwindow,
@@ -970,8 +968,6 @@ failure:
 
 cleanup:
 	m_free(type);
-	
-	update_channel_prio();
 
 	TRACE(("leave recv_msg_channel_open"))
 }
@@ -1166,11 +1162,8 @@ void recv_msg_channel_open_confirmation() {
 		}
 	}
 
-	if (channel->prio == DROPBEAR_CHANNEL_PRIO_EARLY) {
-		channel->prio = DROPBEAR_CHANNEL_PRIO_BULK;
-	}
 	update_channel_prio();
-	
+
 	TRACE(("leave recv_msg_channel_open_confirmation"))
 }
 
diff --git a/common-session.c b/common-session.c
index bfe6284..3d406b1 100644
--- a/common-session.c
+++ b/common-session.c
@@ -64,7 +64,7 @@ void common_session_init(int sock_in, int sock_out) {
 		setnonblocking(sock_out);
 	}
 
-	ses.socket_prio = DROPBEAR_PRIO_DEFAULT;
+	ses.socket_prio = DROPBEAR_PRIO_NORMAL;
 	/* Sets it to lowdelay */
 	update_channel_prio();
 
@@ -667,26 +667,16 @@ void update_channel_prio() {
 		return;
 	}
 
-	new_prio = DROPBEAR_PRIO_BULK;
+	new_prio = DROPBEAR_PRIO_NORMAL;
 	for (i = 0; i < ses.chansize; i++) {
 		struct Channel *channel = ses.channels[i];
-		if (!channel || channel->prio == DROPBEAR_CHANNEL_PRIO_EARLY) {
-			if (channel && channel->prio == DROPBEAR_CHANNEL_PRIO_EARLY) {
-				TRACE(("update_channel_prio: early %d", channel->index))
-			}
+		if (!channel) {
 			continue;
 		}
 		any = 1;
-		if (channel->prio == DROPBEAR_CHANNEL_PRIO_INTERACTIVE)
-		{
-			TRACE(("update_channel_prio: lowdelay %d", channel->index))
+		if (channel->prio == DROPBEAR_PRIO_LOWDELAY) {
 			new_prio = DROPBEAR_PRIO_LOWDELAY;
 			break;
-		} else if (channel->prio == DROPBEAR_CHANNEL_PRIO_UNKNOWABLE
-			&& new_prio == DROPBEAR_PRIO_BULK)
-		{
-			TRACE(("update_channel_prio: unknowable %d", channel->index))
-			new_prio = DROPBEAR_PRIO_DEFAULT;
 		}
 	}
 
diff --git a/netio.c b/netio.c
index 4f0a5fd..d466de5 100644
--- a/netio.c
+++ b/netio.c
@@ -20,6 +20,7 @@ struct dropbear_progress_connection {
 
 	char* errstring;
 	char *bind_address, *bind_port;
+	enum dropbear_prio prio;
 };
 
 /* Deallocate a progress connection. Removes from the pending list if iter!=NULL.
@@ -110,6 +111,7 @@ static void connect_try_next(struct dropbear_progress_connection *c) {
 
 		ses.maxfd = MAX(ses.maxfd, c->sock);
 		set_sock_nodelay(c->sock);
+		set_sock_priority(c->sock, c->prio);
 		setnonblocking(c->sock);
 
 #if DROPBEAR_CLIENT_TCP_FAST_OPEN
@@ -172,8 +174,8 @@ static void connect_try_next(struct dropbear_progress_connection *c) {
 
 /* Connect via TCP to a host. */
 struct dropbear_progress_connection *connect_remote(const char* remotehost, const char* remoteport,
-	connect_callback cb, void* cb_data, 
-	const char* bind_address, const char* bind_port)
+	connect_callback cb, void* cb_data,
+	const char* bind_address, const char* bind_port, enum dropbear_prio prio)
 {
 	struct dropbear_progress_connection *c = NULL;
 	int err;
@@ -185,6 +187,7 @@ struct dropbear_progress_connection *connect_remote(const char* remotehost, cons
 	c->sock = -1;
 	c->cb = cb;
 	c->cb_data = cb_data;
+	c->prio = prio;
 
 	list_append(&ses.conn_pending, c);
 
@@ -378,10 +381,8 @@ void set_sock_priority(int sock, enum dropbear_prio prio) {
 	/* Set the DSCP field for outbound IP packet priority.
 	rfc4594 has some guidance to meanings.
 
-	We set AF21 as "Low-Latency" class for interactive (tty session).
-	Set AF11 "High-Throughput" for bulk data (which includes things
-	such as git over ssh). We usually want higher priority than
-	CS1/LE least effort.
+	We set AF21 as "Low-Latency" class for interactive (tty session,
+	also handshake/setup packets). Other traffic is left at the default.
 
 	OpenSSH at present uses AF21/CS1, rationale
 	https://cvsweb.openbsd.org/src/usr.bin/ssh/readconf.c#rev1.284
@@ -391,8 +392,6 @@ void set_sock_priority(int sock, enum dropbear_prio prio) {
 	*/
 	if (prio == DROPBEAR_PRIO_LOWDELAY) {
 		val = IPTOS_DSCP_AF21;
-	} else if (prio == DROPBEAR_PRIO_BULK) {
-		val = IPTOS_DSCP_AF11;
 	} else {
 		val = 0; /* default */
 	}
@@ -412,8 +411,6 @@ void set_sock_priority(int sock, enum dropbear_prio prio) {
 	/* Set scheduling priority within the local Linux network stack */
 	if (prio == DROPBEAR_PRIO_LOWDELAY) {
 		val = TC_PRIO_INTERACTIVE;
-	} else if (prio == DROPBEAR_PRIO_BULK) {
-		val = TC_PRIO_BULK;
 	} else {
 		val = 0;
 	}
diff --git a/netio.h b/netio.h
index d61ef5e..605512b 100644
--- a/netio.h
+++ b/netio.h
@@ -6,9 +6,8 @@
 #include "queue.h"
 
 enum dropbear_prio {
-	DROPBEAR_PRIO_DEFAULT = 10,
-	DROPBEAR_PRIO_LOWDELAY = 11,
-	DROPBEAR_PRIO_BULK = 12,
+	DROPBEAR_PRIO_NORMAL = 0, /* the rest - tcp-fwd, scp, rsync, git, etc */
+	DROPBEAR_PRIO_LOWDELAY, /* pty shell, x11 */
 };
 
 void set_sock_nodelay(int sock);
@@ -30,7 +29,8 @@ typedef void(*connect_callback)(int result, int sock, void* data, const char* er
 
 /* Always returns a progress connection, if it fails it will call the callback at a later point */
 struct dropbear_progress_connection * connect_remote (const char* remotehost, const char* remoteport,
-	connect_callback cb, void *cb_data, const char* bind_address, const char* bind_port);
+	connect_callback cb, void *cb_data, const char* bind_address, const char* bind_port,
+	enum dropbear_prio prio);
 
 /* Sets up for select() */
 void set_connect_fds(fd_set *writefd);
diff --git a/svr-chansession.c b/svr-chansession.c
index 6c29b17..e0e1d31 100644
--- a/svr-chansession.c
+++ b/svr-chansession.c
@@ -277,7 +277,8 @@ static int newchansess(struct Channel *channel) {
 	chansess->agentdir = NULL;
 #endif
 
-	channel->prio = DROPBEAR_CHANNEL_PRIO_INTERACTIVE;
+	/* Will drop to DROPBEAR_PRIO_NORMAL if a non-tty command starts */
+	channel->prio = DROPBEAR_PRIO_LOWDELAY;
 
 	return 0;
 
@@ -734,7 +735,7 @@ static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
 		/* no pty */
 		ret = noptycommand(channel, chansess);
 		if (ret == DROPBEAR_SUCCESS) {
-			channel->prio = DROPBEAR_CHANNEL_PRIO_BULK;
+			channel->prio = DROPBEAR_PRIO_NORMAL;
 			update_channel_prio();
 		}
 	} else {
diff --git a/svr-tcpfwd.c b/svr-tcpfwd.c
index 9c1edd4..4aa3152 100644
--- a/svr-tcpfwd.c
+++ b/svr-tcpfwd.c
@@ -60,7 +60,7 @@ static int newtcpdirect(struct Channel * channel);
 #if DROPBEAR_SVR_REMOTETCPFWD
 static const struct ChanType svr_chan_tcpremote = {
 	"forwarded-tcpip",
-	tcp_prio_inithandler,
+	NULL,
 	NULL,
 	NULL,
 	NULL,
@@ -289,11 +289,10 @@ static int newtcpdirect(struct Channel * channel) {
 		goto out;
 	}
 
-	channel->prio = DROPBEAR_CHANNEL_PRIO_UNKNOWABLE;
-
 	snprintf(portstring, sizeof(portstring), "%u", destport);
-	channel->conn_pending = connect_remote(desthost, portstring, channel_connect_done, channel, NULL, NULL);
-	
+	channel->conn_pending = connect_remote(desthost, portstring, channel_connect_done,
+		channel, NULL, NULL, DROPBEAR_PRIO_NORMAL);
+
 	err = SSH_OPEN_IN_PROGRESS;
 
 out:
diff --git a/tcp-accept.c b/tcp-accept.c
index 6578d71..73cfa54 100644
--- a/tcp-accept.c
+++ b/tcp-accept.c
@@ -45,13 +45,6 @@ static void cleanup_tcp(const struct Listener *listener) {
 	m_free(tcpinfo);
 }
 
-int tcp_prio_inithandler(struct Channel* channel)
-{
-	TRACE(("tcp_prio_inithandler channel %d", channel->index))
-	channel->prio = DROPBEAR_CHANNEL_PRIO_UNKNOWABLE;
-	return 0;
-}
-
 static void tcp_acceptor(const struct Listener *listener, int sock) {
 
 	int fd;
diff --git a/tcpfwd.h b/tcpfwd.h
index fa81fa4..69e5af2 100644
--- a/tcpfwd.h
+++ b/tcpfwd.h
@@ -71,7 +71,6 @@ void cli_recv_msg_request_failure(void);
 
 /* Common */
 int listen_tcpfwd(struct TCPListener* tcpinfo, struct Listener **ret_listener);
-int tcp_prio_inithandler(struct Channel* chan);
 
 /* A random identifier */
 #define CHANNEL_ID_TCPFORWARDED 0x43612c67