- markus@cvs.openbsd.org 2002/03/25 21:13:51

     [channels.c channels.h compat.c compat.h nchan.c]
     don't send stderr data after EOF, accept this from older known (broken)
     sshd servers only, fixes http://bugzilla.mindrot.org/show_bug.cgi?id=179

6 files changed, 84 insertions, 49 deletions

diff --git a/ChangeLog b/ChangeLog
index 87039872..a3a918b7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -39,6 +39,10 @@
    - markus@cvs.openbsd.org 2002/03/25 21:04:02
      [ssh.c]
      simplify num_identity_files handling
+   - markus@cvs.openbsd.org 2002/03/25 21:13:51
+     [channels.c channels.h compat.c compat.h nchan.c]
+     don't send stderr data after EOF, accept this from older known (broken)
+     sshd servers only, fixes http://bugzilla.mindrot.org/show_bug.cgi?id=179
 
 20020324
  - (stevesk) [session.c] disable LOGIN_NEEDS_TERM until we are sure
@@ -8053,4 +8057,4 @@
  - Wrote replacements for strlcpy and mkdtemp
  - Released 1.0pre1
 
-$Id: ChangeLog,v 1.1989 2002/03/26 03:23:00 mouring Exp $
+$Id: ChangeLog,v 1.1990 2002/03/26 03:26:24 mouring Exp $
diff --git a/channels.c b/channels.c
index 2b1f33f3..95817624 100644
--- a/channels.c
+++ b/channels.c
@@ -39,7 +39,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: channels.c,v 1.171 2002/03/04 19:37:58 markus Exp $");
+RCSID("$OpenBSD: channels.c,v 1.172 2002/03/25 21:13:51 markus Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -706,7 +706,11 @@ channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 		if (buffer_len(&c->output) > 0) {
 			FD_SET(c->wfd, writeset);
 		} else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
-			chan_obuf_empty(c);
+			if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
+                               debug2("channel %d: obuf_empty delayed efd %d/(%d)",
+                                   c->self, c->efd, buffer_len(&c->extended));
+			else
+				chan_obuf_empty(c);
 		}
 	}
 	/** XXX check close conditions, too */
@@ -714,7 +718,8 @@ channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 		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 &&
+		else if (!(c->flags & CHAN_EOF_SENT) &&
+		    c->extended_usage == CHAN_EXTENDED_READ &&
 		    buffer_len(&c->extended) < c->remote_window)
 			FD_SET(c->efd, readset);
 	}
@@ -1632,12 +1637,18 @@ channel_output_poll(void)
 				fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
 			/*
 			 * input-buffer is empty and read-socket shutdown:
-			 * tell peer, that we will not send more data: send IEOF
+			 * tell peer, that we will not send more data: send IEOF.
+			 * hack for extended data: delay EOF if EFD still in use.
 			 */
-			chan_ibuf_empty(c);
+			if (CHANNEL_EFD_INPUT_ACTIVE(c))
+                               debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
+                                   c->self, c->efd, buffer_len(&c->extended));
+			else
+				chan_ibuf_empty(c);
 		}
 		/* Send extended data, i.e. stderr */
 		if (compat20 &&
+		    !(c->flags & CHAN_EOF_SENT) &&
 		    c->remote_window > 0 &&
 		    (len = buffer_len(&c->extended)) > 0 &&
 		    c->extended_usage == CHAN_EXTENDED_READ) {
@@ -1726,6 +1737,13 @@ channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
 		log("channel %d: ext data for non open", id);
 		return;
 	}
+	if (c->flags & CHAN_EOF_RCVD) {
+		if (datafellows & SSH_BUG_EXTEOF)
+			debug("channel %d: accepting ext data after eof", id);
+		else
+			packet_disconnect("Received extended_data after EOF "
+			    "on channel %d.", id);
+	}
 	tcode = packet_get_int();
 	if (c->efd == -1 ||
 	    c->extended_usage != CHAN_EXTENDED_WRITE ||
diff --git a/channels.h b/channels.h
index 707d9a92..0da2d4e5 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: channels.h,v 1.65 2002/03/04 17:27:39 stevesk Exp $	*/
+/*	$OpenBSD: channels.h,v 1.66 2002/03/25 21:13:51 markus Exp $	*/
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -135,6 +135,18 @@ struct Channel {
 
 #define CHAN_CLOSE_SENT			0x01
 #define CHAN_CLOSE_RCVD			0x02
+#define CHAN_EOF_SENT			0x04
+#define CHAN_EOF_RCVD			0x08
+
+/* check whether 'efd' is still in use */
+#define CHANNEL_EFD_INPUT_ACTIVE(c) \
+	(compat20 && c->extended_usage == CHAN_EXTENDED_READ && \
+	(c->efd != -1 || \
+	buffer_len(&c->extended) > 0))
+#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
+	(compat20 && c->extended_usage == CHAN_EXTENDED_WRITE && \
+	((c->efd != -1 && !(c->flags & CHAN_EOF_RCVD)) || \
+	buffer_len(&c->extended) > 0))
 
 /* channel management */
 
diff --git a/compat.c b/compat.c
index 74d5ed85..8671e641 100644
--- a/compat.c
+++ b/compat.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: compat.c,v 1.61 2002/03/06 00:24:39 markus Exp $");
+RCSID("$OpenBSD: compat.c,v 1.62 2002/03/25 21:13:51 markus Exp $");
 
 #include "buffer.h"
 #include "packet.h"
@@ -61,20 +61,26 @@ compat_datafellows(const char *version)
 		  "OpenSSH-2.1*,"
 		  "OpenSSH_2.1*,"
 		  "OpenSSH_2.2*",	SSH_OLD_SESSIONID|SSH_BUG_BANNER|
-					SSH_OLD_DHGEX|SSH_BUG_NOREKEY },
+					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
+					SSH_BUG_EXTEOF},
 		{ "OpenSSH_2.3.0*",	SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES|
-					SSH_OLD_DHGEX|SSH_BUG_NOREKEY},
+					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
+					SSH_BUG_EXTEOF},
 		{ "OpenSSH_2.3.*",	SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
-					SSH_BUG_NOREKEY},
+					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
 		{ "OpenSSH_2.5.0p1*,"
 		  "OpenSSH_2.5.1p1*",
 					SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
-					SSH_BUG_NOREKEY },
+					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
 		{ "OpenSSH_2.5.0*,"
 		  "OpenSSH_2.5.1*,"
-		  "OpenSSH_2.5.2*",	SSH_OLD_DHGEX|SSH_BUG_NOREKEY },
-		{ "OpenSSH_2.5.3*",	SSH_BUG_NOREKEY },
-		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY },
+		  "OpenSSH_2.5.2*",	SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
+					SSH_BUG_EXTEOF},
+		{ "OpenSSH_2.5.3*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
+		{ "OpenSSH_2.*,"
+		  "OpenSSH_3.0*,"
+		  "OpenSSH_3.1*",	SSH_BUG_EXTEOF},
+		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
 		{ "OpenSSH*",		0 },
 		{ "*MindTerm*",		0 },
 		{ "2.1.0*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
diff --git a/compat.h b/compat.h
index 0eeb782e..3fb0f979 100644
--- a/compat.h
+++ b/compat.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: compat.h,v 1.30 2002/03/04 17:27:39 stevesk Exp $	*/
+/*	$OpenBSD: compat.h,v 1.31 2002/03/25 21:13:51 markus Exp $	*/
 
 /*
  * Copyright (c) 1999, 2000, 2001 Markus Friedl.  All rights reserved.
@@ -52,6 +52,7 @@
 #define SSH_BUG_OPENFAILURE	0x00020000
 #define SSH_BUG_DERIVEKEY	0x00040000
 #define SSH_BUG_DUMMYCHAN	0x00100000
+#define SSH_BUG_EXTEOF		0x00200000
 
 void     enable_compat13(void);
 void     enable_compat20(void);
diff --git a/nchan.c b/nchan.c
index fc8e7f18..db38de6a 100644
--- a/nchan.c
+++ b/nchan.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: nchan.c,v 1.44 2002/01/21 23:27:10 markus Exp $");
+RCSID("$OpenBSD: nchan.c,v 1.45 2002/03/25 21:13:51 markus Exp $");
 
 #include "ssh1.h"
 #include "ssh2.h"
@@ -302,6 +302,7 @@ static void
 chan_rcvd_eof2(Channel *c)
 {
 	debug("channel %d: rcvd eof", c->self);
+	c->flags |= CHAN_EOF_RCVD;
 	if (c->ostate == CHAN_OUTPUT_OPEN)
 		chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 }
@@ -330,6 +331,7 @@ chan_send_eof2(Channel *c)
 		packet_start(SSH2_MSG_CHANNEL_EOF);
 		packet_put_int(c->remote_id);
 		packet_send();
+		c->flags |= CHAN_EOF_SENT;
 		break;
 	default:
 		error("channel %d: cannot send eof for istate %d",
@@ -365,7 +367,8 @@ chan_rcvd_ieof(Channel *c)
 	else
 		chan_rcvd_ieof1(c);
 	if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
-	    buffer_len(&c->output) == 0)
+	    buffer_len(&c->output) == 0 && 
+	    !CHANNEL_EFD_OUTPUT_ACTIVE(c))
 		chan_obuf_empty(c);
 }
 void
@@ -404,39 +407,30 @@ chan_is_dead(Channel *c, int send)
 		debug("channel %d: is dead", c->self);
 		return 1;
 	}
-	/*
-	 * we have to delay the close message if the efd (for stderr) is
-	 * still active
-	 */
-	if (((c->extended_usage != CHAN_EXTENDED_IGNORE) &&
-	    buffer_len(&c->extended) > 0)
-#if 0
-	    || ((c->extended_usage == CHAN_EXTENDED_READ) &&
-	    c->efd != -1)
-#endif
-	    ) {
-		debug2("channel %d: active efd: %d len %d type %s",
-		    c->self, c->efd, buffer_len(&c->extended),
-		    c->extended_usage==CHAN_EXTENDED_READ ?
-		    "read": "write");
-	} else {
-		if (!(c->flags & CHAN_CLOSE_SENT)) {
-			if (send) {
-				chan_send_close2(c);
-			} else {
-				/* channel would be dead if we sent a close */
-				if (c->flags & CHAN_CLOSE_RCVD) {
-					debug("channel %d: almost dead",
-					    c->self);
-					return 1;
-				}
+	if ((datafellows & SSH_BUG_EXTEOF) &&
+	    c->extended_usage == CHAN_EXTENDED_WRITE &&
+	    c->efd != -1 &&
+	    buffer_len(&c->extended) > 0) {
+                debug2("channel %d: active efd: %d len %d",
+                    c->self, c->efd, buffer_len(&c->extended));
+		return 0;
+	}
+	if (!(c->flags & CHAN_CLOSE_SENT)) {
+		if (send) {
+			chan_send_close2(c);
+		} else {
+			/* channel would be dead if we sent a close */
+			if (c->flags & CHAN_CLOSE_RCVD) {
+				debug("channel %d: almost dead",
+				    c->self);
+				return 1;
 			}
 		}
-		if ((c->flags & CHAN_CLOSE_SENT) &&
-		    (c->flags & CHAN_CLOSE_RCVD)) {
-			debug("channel %d: is dead", c->self);
-			return 1;
-		}
+	}
+	if ((c->flags & CHAN_CLOSE_SENT) &&
+	    (c->flags & CHAN_CLOSE_RCVD)) {
+		debug("channel %d: is dead", c->self);
+		return 1;
 	}
 	return 0;
 }