From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon,  1 Dec 2008 14:24:27 -0500
From: Ishwar Rattan <ishwar@pali.cps.cmich.edu>
To: 9fans@9fans.net
Message-ID: <Pine.LNX.4.64.0812011420190.6464@pali.cps.cmich.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Subject: [9fans] UDP insight needed..
Topicbox-Message-UUID: 55375b22-ead4-11e9-9d60-3106f5b1d025


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);
}
--------