Re: [RFA] Remote UDP support

Daniel Jacobowitz
2002-05-11T21:32:25Z

On Sat, May 11, 2002 at 03:13:02PM -0400, Andrew Cagney wrote:
> >No. I think it need to be in the users face. I don't think GDB should
> >>silently let the user to use a broken mechanism.
> >
> >
> >I really don't agree, but your call. Could I at least persuade you
> >down to a one-line warning and no confirmation query?
>
> Oh! All right then :-)

How's this look? I wasn't quite sure what to put in the text of the
warning. Also added one to the manual.

--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer

Index: ser-tcp.c
===================================================================
RCS file: /cvs/src/src/gdb/ser-tcp.c,v
retrieving revision 1.10
diff -u -p -r1.10 ser-tcp.c
--- ser-tcp.c 18 Dec 2001 18:54:18 -0000 1.10
+++ ser-tcp.c 11 May 2002 21:19:41 -0000
@@ -38,12 +38,15 @@
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
+#include <netinet/udp.h>

#include <signal.h>
#include "gdb_string.h"

-static int tcp_open (struct serial *scb, const char *name);
-static void tcp_close (struct serial *scb);
+static int udp_warning = 0;
+
+static int net_open (struct serial *scb, const char *name);
+static void net_close (struct serial *scb);
extern int (*ui_loop_hook) (int);
void _initialize_ser_tcp (void);

@@ -55,17 +58,35 @@ void _initialize_ser_tcp (void);
/* Open a tcp socket */

static int
-tcp_open (struct serial *scb, const char *name)
+net_open (struct serial *scb, const char *name)
{
char *port_str, hostname[100];
int n, port, tmp;
+ int use_udp;
struct hostent *hostent;
struct sockaddr_in sockaddr;

+ use_udp = 0;
+ if (strncmp (name, "udp:", 4) == 0)
+ {
+ use_udp = 1;
+ name = name + 4;
+
+ if (udp_warning == 0)
+ {
+ udp_warning = 1;
+ warning ("UDP debugging is unreliable.");
+ warning ("Some events may be lost, rendering further debugging "
+ "impossible.");
+ }
+ }
+ else if (strncmp (name, "tcp:", 4) == 0)
+ name = name + 4;
+
port_str = strchr (name, ':');

if (!port_str)
- error ("tcp_open: No colon in host name!"); /* Shouldn't ever happen */
+ error ("net_open: No colon in host name!"); /* Shouldn't ever happen */

tmp = min (port_str - name, (int) sizeof hostname - 1);
strncpy (hostname, name, tmp); /* Don't want colon */
@@ -84,7 +105,11 @@ tcp_open (struct serial *scb, const char
return -1;
}

- scb->fd = socket (PF_INET, SOCK_STREAM, 0);
+ if (use_udp)
+ scb->fd = socket (PF_INET, SOCK_DGRAM, 0);
+ else
+ scb->fd = socket (PF_INET, SOCK_STREAM, 0);
+
if (scb->fd < 0)
return -1;

@@ -102,7 +127,7 @@ tcp_open (struct serial *scb, const char

if (n < 0 && errno != EINPROGRESS)
{
- tcp_close (scb);
+ net_close (scb);
return -1;
}

@@ -124,7 +149,7 @@ tcp_open (struct serial *scb, const char
if (ui_loop_hook (0))
{
errno = EINTR;
- tcp_close (scb);
+ net_close (scb);
return -1;
}
}
@@ -142,7 +167,7 @@ tcp_open (struct serial *scb, const char
{
if (polls > TIMEOUT * POLL_INTERVAL)
errno = ETIMEDOUT;
- tcp_close (scb);
+ net_close (scb);
return -1;
}
}
@@ -156,20 +181,23 @@ tcp_open (struct serial *scb, const char
{
if (err)
errno = err;
- tcp_close (scb);
+ net_close (scb);
return -1;
}
}
-
+
/* turn off nonblocking */
tmp = 0;
ioctl (scb->fd, FIONBIO, &tmp);

- /* Disable Nagle algorithm. Needed in some cases. */
- tmp = 1;
- setsockopt (scb->fd, IPPROTO_TCP, TCP_NODELAY,
- (char *)&tmp, sizeof (tmp));
-
+ if (use_udp == 0)
+ {
+ /* Disable Nagle algorithm. Needed in some cases. */
+ tmp = 1;
+ setsockopt (scb->fd, IPPROTO_TCP, TCP_NODELAY,
+ (char *)&tmp, sizeof (tmp));
+ }
+
/* If we don't do this, then GDB simply exits
when the remote side dies. */
signal (SIGPIPE, SIG_IGN);
@@ -178,7 +206,7 @@ tcp_open (struct serial *scb, const char
}

static void
-tcp_close (struct serial *scb)
+net_close (struct serial *scb)
{
if (scb->fd < 0)
return;
@@ -194,8 +222,8 @@ _initialize_ser_tcp (void)
memset (ops, sizeof (struct serial_ops), 0);
ops->name = "tcp";
ops->next = 0;
- ops->open = tcp_open;
- ops->close = tcp_close;
+ ops->open = net_open;
+ ops->close = net_close;
ops->readchar = ser_unix_readchar;
ops->write = ser_unix_write;
ops->flush_output = ser_unix_nop_flush_output;
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.98
diff -u -p -r1.98 gdb.texinfo
--- doc/gdb.texinfo 4 May 2002 16:00:30 -0000 1.98
+++ doc/gdb.texinfo 11 May 2002 21:21:23 -0000
@@ -10475,7 +10475,7 @@ of its pure text.
Establish communication using the @code{target remote} command.
Its argument specifies how to communicate with the target
machine---either via a devicename attached to a direct serial line, or a
-TCP port (usually to a terminal server which in turn has a serial line
+TCP or UDP port (usually to a terminal server which in turn has a serial line
to the target). For example, to use a serial line connected to the
device named @file{/dev/ttyb}:

@@ -10485,7 +10485,8 @@ target remote /dev/ttyb

@cindex TCP port, @code{target remote}
To use a TCP connection, use an argument of the form
-@code{@var{host}:port}. For example, to connect to port 2828 on a
+@code{@var{host}:@var{port}} or @code{tcp:@var{host}:@var{port}}.
+For example, to connect to port 2828 on a
terminal server named @code{manyfarms}:

@smallexample
@@ -10503,6 +10504,21 @@ target remote :1234
@noindent

Note that the colon is still required here.
+
+@cindex UDP port, @code{target remote}
+To use a UDP connection, use an argument of the form
+@code{udp:@var{host}:@var{port}}. For example, to connect to UDP port 2828
+on a terminal server named @code{manyfarms}:
+
+@smallexample
+target remote udp:manyfarms:2828
+@end smallexample
+
+When using a UDP connection for remote debugging, you should keep in mind
+that the `U' stands for ``Unreliable''. UDP can silently drop packets on
+busy or unreliable networks, which will cause havoc with your debugging
+session.
+
@end enumerate

Now you can use all the usual commands to examine and change data and to