Re: [RFA] Remote UDP support

Michael Snyder
2002-05-08T23:58:00Z

Daniel Jacobowitz wrote:
>
> A patch for this feature was supported a year or so ago, but never went in.
> I had a need for this a couple of days ago, so I did it over from scratch;
> it's much easier now than it was at the time. The name of ser-tcp.c is a
> bit wrong after this patch; I can either rename the file to ser-net.c or
> just update some comments to match. Got a preference? Otherwise OK?
>
> --
> Daniel Jacobowitz Carnegie Mellon University
> MontaVista Software Debian GNU/Linux Developer

Wow! I love the simplicity of the change. Nice job.
I'm not sure if I understand all the ramifications, though.
If you call net_open, how is it going to decide whether
to use udp or tcp? I imagine we would want it to use
tcp by preference, if possible.

>
> 2002-05-08 Daniel Jacobowitz <drow@mvista.com>
>
> * ser-tcp.c: Include <netinet/udp.h>. Rename tcp_open
> and tcp_close to net_open and net_close.
> (net_open): Accept "udp:" and "tcp:" specifications. Connect
> using UDP if requested. Don't try to disable Nagle on UDP
> sockets.
>
> 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 8 May 2002 23:21:58 -0000
> @@ -38,12 +38,13 @@
> #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 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 +56,27 @@ 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;
> + }
> + 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 +95,11 @@ 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 +117,7 @@ tcp_open (struct serial *scb, const char
>
> if (n < 0 && errno != EINPROGRESS)
> {
> - tcp_close (scb);
> + net_close (scb);
> return -1;
> }
>
> @@ -124,7 +139,7 @@ tcp_open (struct serial *scb, const char
> if (ui_loop_hook (0))
> {
> errno = EINTR;
> - tcp_close (scb);
> + net_close (scb);
> return -1;
> }
> }
> @@ -142,7 +157,7 @@ tcp_open (struct serial *scb, const char
> {
> if (polls > TIMEOUT * POLL_INTERVAL)
> errno = ETIMEDOUT;
> - tcp_close (scb);
> + net_close (scb);
> return -1;
> }
> }
> @@ -156,20 +171,23 @@ 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 +196,7 @@ 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 +212,8 @@ _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;