support for SSH protocol 1.5 which is poorly documented, the RFC.troff lies.

interops (x11,agent,etc) with 1.2.27 and protocol 1.3

1 files changed, 78 insertions, 0 deletions

diff --git a/usr.bin/ssh/nchan.h b/usr.bin/ssh/nchan.h
new file mode 100644
index 00000000000..b83cf2de035
--- /dev/null
+++ b/usr.bin/ssh/nchan.h
@@ -0,0 +1,78 @@
+#ifndef NCHAN_H
+#define NCHAN_H
+
+
+/*
+	SSH Protocol 1.5 aka New Channel Protocol
+	Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored.
+	Written by Markus Friedl in October 1999
+
+	Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the
+	tear down of channels:
+
+	1.3:	strict request-ack-protocol:
+		CLOSE	->
+			<-  CLOSE_CONFIRM
+
+	1.5:	uses variations of:
+		IEOF	->
+			<-  OCLOSE
+			<-  IEOF
+		OCLOSE	->
+
+	See the debugging output from 'ssh -v' and 'sshd -d' in ssh-1.2.27, for example.
+
+	Details: (for Channel data structure see channels.h)
+
+	the output_buffer gets data received from the remote peer and is written to the socket,
+	the input_buffer gets data from the socket and is sent to remote peer.
+	the socket represents the local object communicating with an object reachable via the peer
+
+		PEER A					PEER B
+
+	read(sock, input_buffer) < 0;
+	shutdown_read();
+	flush(input_buffer) =: DATA
+	send(DATA)			->      rcvd(DATA)                                         
+						write(sock, output_buffer:=DATA);                  
+	send(IEOF)			->	rcvd(IEOF)                                         
+						shutdown_write() if:                               
+							a) write fails                             
+							b) rcvd_IEOF==true && output_buffer==empty
+					<-	send(OCLOSE)
+	rcvd(OCLOSE)				destroy channel
+	shutdown_read() if not already
+	destroy channel
+
+	Note that each side can close the channel only if 2 messages
+	have been sent and received and the associated socket has been shutdown, see below:
+*/
+
+
+enum {
+	/* ssh-proto-1.5 overloads message-types */
+	CHAN_IEOF   = SSH_MSG_CHANNEL_CLOSE,			/* no more data from sender */
+	CHAN_OCLOSE = SSH_MSG_CHANNEL_CLOSE_CONFIRMATION,	/* all received data has been output */
+
+	/* channel close flags */
+	CHAN_IEOF_SENT 		= 0x01,	
+	CHAN_IEOF_RCVD 		= 0x02,	
+	CHAN_OCLOSE_SENT 	= 0x04,
+	CHAN_OCLOSE_RCVD 	= 0x08,
+	CHAN_SHUT_RD 		= 0x10,
+	CHAN_SHUT_WR 		= 0x20,	
+
+	/* a channel can be removed if ALL the following flags are set: */
+	CHAN_CLOSED 		= CHAN_IEOF_SENT | CHAN_IEOF_RCVD |
+				  CHAN_OCLOSE_SENT | CHAN_OCLOSE_RCVD |
+				  CHAN_SHUT_RD | CHAN_SHUT_WR
+};
+
+void chan_del_if_dead(Channel *c);
+void chan_rcvd_ieof(Channel *c);
+void chan_rcvd_oclose(Channel *c);
+void chan_send_ieof(Channel *c);
+void chan_send_oclose(Channel *c);
+void chan_shutdown_read(Channel *c);
+void chan_shutdown_write(Channel *c);
+#endif