[9fans] UDP insight needed..

[9fans] UDP insight needed..

[Ishwar Rattan]

Trying to get UDP working with announce.dial and friends.
Code for an attempted UDP server/client listed below.
The server does not get beyond the read() call -- as if the
client never got connected. Dial() in client does not return
error. Any pointers will bve appreciated.

-ishwar
-------server.c---
/* Example of a server, echoes back the
  * info received from a client
  * It does not complete the read()..
  */

#include <u.h>
#include <libc.h>
#include <ip.h>

void
main(void)
{
    int afd, lcfd;
    char adir[40], ldir[40];
    int i, n;
    char buf[256];


    afd = announce("udp!*!8001", adir);
    if(afd < 0) sysfatal("announce..\n");
    if(fprint(afd, "headers") < 0)
        fprint(2, "headers..\n");
    sprint(ldir, "%s/data", adir);
    lcfd = open(ldir, ORDWR);
    if(lcfd < 0) {
 	close(afd); sysfatal("listen..\n");
    }
    n = read(lcfd, buf, 256);
    if(n <=0) {
    	close(afd); close(lcfd); sysfatal("read..\n");
    }
    for(i = 0; i < 12; i++)
         print("%x ", (uchar *)(buf+i));
    print("\n");

    close(afd); close(lcfd);
    exits(nil);
}
--------client.c---
/* Client code for echo client..
  */

#include <u.h>
#include <libc.h>

void
main(void)
{
    char buf[128], *string = "Message to server.";
    int fd, len;


    if((fd = dial("udp!localhost!8001", 0, 0, 0)) < 0)
 	sysfatal("dial");
    print("after dial..\n");
    srand((long)i);
    sprint(buf, "%s%d", string, rand());
    len = strlen(buf) + 1;
    if(write(fd, buf, len) != len) {
 		close(fd); sysfatal("write..\n"); }
     buf[0] =  0;
     read(fd, buf, 128);
     close(fd);
     exits(nil);
}
--------

Re: [9fans] UDP insight needed..

[erik quanstrom]

[-- Attachment #1: Type: text/plain, Size: 349 bytes --]

i believe the calls to listen an accept were
missing.  i added a function to the client to
determine the local address so we don't have to
depend on localhost.  (which is never set on my
machines.) and i added a function to the server to
print the caller.

- erik

ps.  would some humane soul please take localhost
out back and shoot it.

[-- Attachment #2: udpclient.c --]
[-- Type: text/plain, Size: 842 bytes --]

#include <u.h>
#include <libc.h>
#include <ip.h>

int
findip(char *s, int len)
{
	Ipifc *ifc;
	Iplifc *l;

	fmtinstall('I', eipfmt);
	for(ifc = readipifc("/net", 0, 0); ifc; ifc = ifc->next)
		for(l = ifc->lifc; l; l = l->next)
			if(l->ip){
//				freeipifc(ifc);
				snprint(s, len, "udp!%I!8001", l->ip);
				return 0;
			}
//	freeipifc(ifc);
	return -1;
}

void
main(void)
{
	char buf[128], ds[64];
	int n, fd, len;

	if(findip(ds, sizeof ds) == -1)
		sysfatal("can't find my ip");
	if((fd = dial(ds, 0, 0, 0)) == -1)
		sysfatal("dial: %r");
	srand(time(0));
	len = sprint(buf, "Message to server%d", rand());
	if(write(fd, buf, len) != len)
		sysfatal("write: %r");
	if((n = read(fd, buf, sizeof buf)) == -1)
		sysfatal("read: %r");
	fprint(2, "read [%.*s]\n", n, buf);

	close(fd);
	exits("");
}

[-- Attachment #3: udpserver.c --]
[-- Type: text/plain, Size: 997 bytes --]

#include <u.h>
#include <libc.h>
#include <ip.h>

char*
remoteaddr(char *dir)
{
	static char buf[128];
	char *p;
	int n, fd;

	snprint(buf, sizeof buf, "%s/remote", dir);
	fd = open(buf, OREAD);
	if(fd < 0)
		return "";
	n = read(fd, buf, sizeof(buf));
	close(fd);
	if(n > 0){
		buf[n] = 0;
		p = strchr(buf, '!');
		if(p)
			*p = 0;
		return buf;
	}
	return "";
}

void
main(void)
{
	char buf[512], dir[40], ndir[40];
	int n, ctl, nctl, fd;

	if((ctl = announce("udp!*!8001", dir)) == -1)
		sysfatal("announce: %r");
	nctl = listen(dir, ndir);
	if(nctl < 0)
		sysfatal("listen %r");

	fd = accept(nctl, ndir);
	if(fd < 0)
		sysfatal("accept: can't open  %s/data: %r", ndir);
	fprint(2, "incoming call from %s in %s\n", remoteaddr(ndir), ndir);

	if((n = read(fd, buf, sizeof buf)) == -1)
		sysfatal("read: %r");
	fprint(2, "read [%.*s]\n", n, buf);

	if(write(fd, buf, n) != n)
		sysfatal("read: %r");

	close(ctl);
	close(nctl);
	exits(0);
}

Re: [9fans] UDP insight needed..

[Gabriel Diaz Lopez de la Llave]

Hello

I think loopback is needed by venti, isn't it?

gabi

El 01/12/2008, a las 23:20, erik quanstrom escribió:

> i believe the calls to listen an accept were
> missing.  i added a function to the client to
> determine the local address so we don't have to
> depend on localhost.  (which is never set on my
> machines.) and i added a function to the server to
> print the caller.
>
> - erik
>
> ps.  would some humane soul please take localhost
> out back and shoot it.
> <udpclient.c><udpserver.c>