Replace ChanType.sepfds with Channel.bidir_fd

This handles the case where a svrchansess has separate FDs
for nopty, but a single FD for pty mode.

The use of sepfds was also previously incorrect for X11 and
agent forwarding

channel.h

@@ -60,6 +60,9 @@ struct Channel {
 	int readfd; /* read from insecure side, written to wire */
 	int errfd; /* used like writefd or readfd, depending if it's client or server.
 				  Doesn't exactly belong here, but is cleaner here */
+	int bidir_fd; /* a boolean indicating that writefd/readfd are the same
+			file descriptor (bidirectional), such as a network socket or PTY.
+			That is handled differently when closing FDs */
 	circbuffer *writebuf; /* data from the wire, for local consumption. Can be
 							 initially NULL */
 	circbuffer *extrabuf; /* extended-data for the program - used like writebuf
@@ -87,7 +90,6 @@ struct Channel {
 
 struct ChanType {
 
-	int sepfds; /* Whether this channel has separate pipes for in/out or not */
 	const char *name;
 	/* Sets up the channel */
 	int (*inithandler)(struct Channel*);

cli-agentfwd.c

@@ -47,7 +47,6 @@
 static int new_agent_chan(struct Channel * channel);
 
 const struct ChanType cli_chan_agent = {
-	0, /* sepfds */
 	"auth-agent@openssh.com",
 	new_agent_chan,
 	NULL,
@@ -94,6 +93,7 @@ static int new_agent_chan(struct Channel * channel) {
 
 	channel->readfd = fd;
 	channel->writefd = fd;
+	channel->bidir_fd = 1;
 
 	return 0;
 }

cli-chansession.c

@@ -46,7 +46,6 @@ static int cli_init_netcat(struct Channel *channel);
 static void cli_tty_setup(void);
 
 const struct ChanType clichansess = {
-	0, /* sepfds */
 	"session", /* name */
 	cli_initchansess, /* inithandler */
 	NULL, /* checkclosehandler */
@@ -344,6 +343,7 @@ static int cli_init_stdpipe_sess(struct Channel *channel) {
 	setnonblocking(STDERR_FILENO);
 
 	channel->extrabuf = cbuf_new(opts.recv_window);
+	channel->bidir_fd = 0;
 	return 0;
 }
 
@@ -383,7 +383,6 @@ static int cli_initchansess(struct Channel *channel) {
 #if DROPBEAR_CLI_NETCAT
 
 static const struct ChanType cli_chan_netcat = {
-	0, /* sepfds */
 	"direct-tcpip",
 	cli_init_netcat, /* inithandler */
 	NULL,

cli-tcpfwd.c

@@ -35,7 +35,6 @@
 static int newtcpforwarded(struct Channel * channel);
 
 const struct ChanType cli_chan_tcpremote = {
-	1, /* sepfds */
 	"forwarded-tcpip",
 	newtcpforwarded,
 	NULL,
@@ -51,7 +50,6 @@ static int cli_localtcp(const char* listenaddr,
 		const char* remoteaddr,
 		unsigned int remoteport);
 static const struct ChanType cli_chan_tcplocal = {
-	1, /* sepfds */
 	"direct-tcpip",
 	tcp_prio_inithandler,
 	NULL,

common-channel.c

@@ -339,6 +339,7 @@ void channel_connect_done(int result, int sock, void* user_data, const char* err
 	if (result == DROPBEAR_SUCCESS)
 	{
 		channel->readfd = channel->writefd = sock;
+		channel->bidir_fd = 1;
 		channel->conn_pending = NULL;
 		send_msg_channel_open_confirmation(channel, channel->recvwindow,
 				channel->recvmaxpacket);
@@ -1039,7 +1040,7 @@ static void close_chan_fd(struct Channel *channel, int fd, int how) {
 
 	int closein = 0, closeout = 0;
 
-	if (channel->type->sepfds) {
+	if (channel->bidir_fd) {
 		TRACE(("SHUTDOWN(%d, %d)", fd, how))
 		shutdown(fd, how);
 		if (how == 0) {
@@ -1069,7 +1070,7 @@ static void close_chan_fd(struct Channel *channel, int fd, int how) {
 
 	/* if we called shutdown on it and all references are gone, then we 
 	 * need to close() it to stop it lingering */
-	if (channel->type->sepfds && channel->readfd == FD_CLOSED 
+	if (channel->bidir_fd && channel->readfd == FD_CLOSED 
 		&& channel->writefd == FD_CLOSED && channel->errfd == FD_CLOSED) {
 		TRACE(("CLOSE (finally) of %d", fd))
 		m_close(fd);
@@ -1102,6 +1103,7 @@ int send_msg_channel_open_init(int fd, const struct ChanType *type) {
 
 	chan->writefd = chan->readfd = fd;
 	ses.maxfd = MAX(ses.maxfd, fd);
+	chan->bidir_fd = 1;
 
 	chan->await_open = 1;
 

svr-agentfwd.c

@@ -186,7 +186,6 @@ void svr_agentcleanup(struct ChanSess * chansess) {
 }
 
 static const struct ChanType chan_svr_agent = {
-	0, /* sepfds */
 	"auth-agent@openssh.com",
 	NULL,
 	NULL,

svr-chansession.c

@@ -64,7 +64,6 @@ static void send_msg_chansess_exitsignal(const struct Channel * channel,
 static void get_termmodes(const struct ChanSess *chansess);
 
 const struct ChanType svrchansess = {
-	0, /* sepfds */
 	"session", /* name */
 	newchansess, /* inithandler */
 	sesscheckclose, /* checkclosehandler */
@@ -769,6 +768,7 @@ static int noptycommand(struct Channel *channel, struct ChanSess *chansess) {
 	ses.maxfd = MAX(ses.maxfd, channel->writefd);
 	ses.maxfd = MAX(ses.maxfd, channel->readfd);
 	ses.maxfd = MAX(ses.maxfd, channel->errfd);
+	channel->bidir_fd = 0;
 
 	addchildpid(chansess, chansess->pid);
 
@@ -895,6 +895,7 @@ static int ptycommand(struct Channel *channel, struct ChanSess *chansess) {
 		channel->readfd = chansess->master;
 		/* don't need to set stderr here */
 		ses.maxfd = MAX(ses.maxfd, chansess->master);
+		channel->bidir_fd = 1;
 
 		setnonblocking(chansess->master);
 

svr-tcpfwd.c

@@ -59,7 +59,6 @@ static int newtcpdirect(struct Channel * channel);
 
 #if DROPBEAR_SVR_REMOTETCPFWD
 static const struct ChanType svr_chan_tcpremote = {
-	1, /* sepfds */
 	"forwarded-tcpip",
 	tcp_prio_inithandler,
 	NULL,
@@ -241,7 +240,6 @@ out:
 #if DROPBEAR_SVR_LOCALTCPFWD
 
 const struct ChanType svr_chan_tcpdirect = {
-	1, /* sepfds */
 	"direct-tcpip",
 	newtcpdirect, /* init */
 	NULL, /* checkclose */

svr-x11fwd.c

@@ -211,7 +211,6 @@ static int x11_inithandler(struct Channel *channel) {
 }
 
 static const struct ChanType chan_x11 = {
-	0, /* sepfds */
 	"x11",
 	x11_inithandler, /* inithandler */
 	NULL, /* checkclose */