Brian Wellington
2001-Sep-20 00:04 UTC
Patch to allow local port forwarding from an existing connection
Hi. Attached is a patch that introduces a new escape character (~c) that
opens a command line. From the command line, a command of the form:
-L port:host:hostport
can be entered, which will forward the local port, as if the same option
has been provided on the command line. I attempted to allow remote port
forwards to be specified similarly, but the server disconnects with a
protocol error (and the code is disabled now).
This is a bit of a hack, but it works, and it's something that I've been
hoping would be added to ssh for a few years now.
The patch is against openssh-2.9p2.
Comments? Any chance this will get integrated?
Brian
-----
--- clientloop.c.old Fri Apr 20 05:50:51 2001
+++ clientloop.c Wed Sep 19 16:51:40 2001
@@ -67,6 +67,7 @@
#include "xmalloc.h"
#include "packet.h"
#include "buffer.h"
+#include "cli.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
@@ -465,6 +466,75 @@
}
}
+void
+process_cmdline(Buffer *bin, Buffer *bout, Buffer *berr)
+{
+ char string[1024];
+ void (*handler)(int);
+ char *s;
+ u_short fwd_port, fwd_host_port;
+ char buf[256];
+ int local = 0;
+ char *msg;
+ int n;
+
+ leave_raw_mode();
+ handler = signal(SIGINT, SIG_IGN);
+ fprintf(stderr, "\r\n> ");
+ s = fgets(string, sizeof string, stdin);
+ if (s == NULL) {
+ msg = NULL;
+ goto out;
+ }
+
+ while (*s && isspace(*s))
+ s++;
+
+ if (*s == 0)
+ goto out;
+
+ if (strlen(s) < 2 || s[0] != '-' || !(s[1] == 'L' || s[1]
== 'R')) {
+ msg = "Invalid command";
+ goto out;
+ }
+ if (s[1] == 'L')
+ local = 1;
+ else {
+ msg = "Remote forwarding doesn't work";
+ goto out;
+ }
+
+ s += 2;
+
+ if (sscanf(s, "%hu/%255[^/]/%hu", &fwd_port, buf,
&fwd_host_port) != 3
+ &&
+ sscanf(s, "%hu:%255[^:]:%hu", &fwd_port, buf,
&fwd_host_port) != 3)
+ {
+ msg = "Invalid port forward";
+ goto out;
+ }
+ if (local) {
+ n = channel_request_local_forwarding(fwd_port, buf,
+ fwd_host_port,
+ options.gateway_ports);
+ if (n <= 0) {
+ msg = "Port forwarding failed";
+ goto out;
+ }
+ }
+ else
+ channel_request_remote_forwarding(fwd_port, buf, fwd_host_port);
+
+ msg = "Forwarding port";
+ out:
+ signal(SIGINT, handler);
+ enter_raw_mode();
+ if (msg) {
+ snprintf(string, sizeof string, "%s\r\n", msg);
+ buffer_append(berr, string, strlen(string));
+ }
+}
+
/* process the characters one by one */
int
process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
@@ -570,6 +640,7 @@
~^Z - suspend ssh\r\n\
~# - list forwarded connections\r\n\
~& - background ssh (when waiting for connections to terminate)\r\n\
+~c - open a command line\r\n
~? - this message\r\n\
~~ - send the escape character by typing it twice\r\n\
(Note that escapes are only recognized immediately after newline.)\r\n",
@@ -583,6 +654,10 @@
s = channel_open_message();
buffer_append(berr, s, strlen(s));
xfree(s);
+ continue;
+
+ case 'c':
+ process_cmdline(bin, bout, berr);
continue;
default:
Markus Friedl
2001-Sep-20 10:04 UTC
Patch to allow local port forwarding from an existing connection
On Wed, Sep 19, 2001 at 05:04:51PM -0700, Brian Wellington wrote:> Hi. Attached is a patch that introduces a new escape character (~c) that > opens a command line. From the command line, a command of the form: > > -L port:host:hostport > > can be entered, which will forward the local port, as if the same option > has been provided on the command line. I attempted to allow remote port > forwards to be specified similarly, but the server disconnects with a > protocol error (and the code is disabled now). > > This is a bit of a hack, but it works, and it's something that I've been > hoping would be added to ssh for a few years now. > > The patch is against openssh-2.9p2. > > Comments? Any chance this will get integrated? > + fprintf(stderr, "\r\n> "); > + s = fgets(string, sizeof string, stdin);i don't think reading from stdin is correct. you need to read from the same FD as bin. can you get the command line from 'bin' ? or perhaps use readpass.[ch] from -current with echo enabled? -m