Re: [RFA] Remote UDP support

[Michael Snyder <msnyder@redhat.com>]

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;