Add ~. and ~^Z handling to exit/suspend dbclient

channel.h

@@ -83,8 +83,10 @@ struct Channel {
 
 	int flushing;
 
-	const struct ChanType* type;
+	/* Used by client chansession to handle ~ escaping, NULL ignored otherwise */
+	void (*read_mangler)(struct Channel*, unsigned char* bytes, int *len);
 
+	const struct ChanType* type;
 };
 
 struct ChanType {

cli-chansession.c

@@ -38,9 +38,10 @@
 static void cli_closechansess(struct Channel *channel);
 static int cli_initchansess(struct Channel *channel);
 static void cli_chansessreq(struct Channel *channel);
-
 static void send_chansess_pty_req(struct Channel *channel);
 static void send_chansess_shell_req(struct Channel *channel);
+static void cli_escape_handler(struct Channel *channel, unsigned char* buf, int *len);
+
 
 static void cli_tty_setup();
 
@@ -374,6 +375,8 @@ static int cli_initchansess(struct Channel *channel) {
 
 	if (cli_opts.wantpty) {
 		cli_tty_setup();
+		channel->read_mangler = cli_escape_handler;
+		cli_ses.last_char = '\r';
 	}	
 
 	return 0; /* Success */
@@ -429,3 +432,59 @@ void cli_send_chansess_request() {
 	TRACE(("leave cli_send_chansess_request"))
 
 }
+
+// returns 1 if the character should be consumed, 0 to pass through
+static int
+do_escape(unsigned char c) {
+	switch (c) {
+		case '.':
+			dropbear_exit("Terminated");
+			return 1;
+			break;
+		case 0x1a:
+			// ctrl-z
+			cli_tty_cleanup();
+			kill(getpid(), SIGTSTP);
+			// after continuation
+			cli_tty_setup();
+			cli_ses.winchange = 1;
+			return 1;
+			break;
+	}
+	return 0;
+}
+
+static
+void cli_escape_handler(struct Channel *channel, unsigned char* buf, int *len) {
+	char c;
+	int skip_char = 0;
+
+	// only handle escape characters if they are read one at a time. simplifies
+	// the code and avoids nasty people putting ~. at the start of a line to paste 
+	if (*len != 1) {
+		cli_ses.last_char = 0x0;
+		return;
+	}
+
+	c = buf[0];
+
+	if (cli_ses.last_char == DROPBEAR_ESCAPE_CHAR) {
+		skip_char = do_escape(c);
+		cli_ses.last_char = 0x0;
+	} else {
+		if (c == DROPBEAR_ESCAPE_CHAR) {
+			if (cli_ses.last_char == '\r') {
+				cli_ses.last_char = DROPBEAR_ESCAPE_CHAR;
+				skip_char = 1;
+			} else {
+				cli_ses.last_char = 0x0;
+			}
+		} else {
+			cli_ses.last_char = c;
+		}
+	}
+
+	if (skip_char) {
+		*len = 0;
+	}
+}

common-channel.c

@@ -643,6 +643,7 @@ static void send_msg_channel_data(struct Channel *channel, int isextended) {
 
 	/* read the data */
 	len = read(fd, buf_getwriteptr(ses.writepayload, maxlen), maxlen);
+
 	if (len <= 0) {
 		if (len == 0 || errno != EINTR) {
 			/* This will also get hit in the case of EAGAIN. The only
@@ -650,12 +651,22 @@ static void send_msg_channel_data(struct Channel *channel, int isextended) {
 			in which case it can be treated the same as EOF */
 			close_chan_fd(channel, fd, SHUT_RD);
 		}
-		ses.writepayload->len = ses.writepayload->pos = 0;
+		buf_setpos(ses.writepayload, 0);
+		buf_setlen(ses.writepayload, 0);
 		TRACE(("leave send_msg_channel_data: len %d read err %d or EOF for fd %d", 
 					len, errno, fd))
 		return;
 	}
 
+	if (channel->read_mangler) {
+		channel->read_mangler(channel, buf_getwriteptr(ses.writepayload, len), &len);
+		if (len == 0) {
+			buf_setpos(ses.writepayload, 0);
+			buf_setlen(ses.writepayload, 0);
+			return;
+		}
+	}
+
 	TRACE(("send_msg_channel_data: len %d fd %d", len, fd))
 	buf_incrwritepos(ses.writepayload, len);
 	/* ... real size here */

session.h

@@ -259,6 +259,9 @@ struct clientsession {
 	int stderrcopy;
 	int stderrflags;
 
+	/* for escape char handling */
+	int last_char;
+
 	int winchange; /* Set to 1 when a windowchange signal happens */
 
 	int lastauthtype; /* either AUTH_TYPE_PUBKEY or AUTH_TYPE_PASSWORD,

sysoptions.h

@@ -54,6 +54,8 @@
 
 #define _PATH_CP "/bin/cp"
 
+#define DROPBEAR_ESCAPE_CHAR '~'
+
 /* success/failure defines */
 #define DROPBEAR_SUCCESS 0
 #define DROPBEAR_FAILURE -1