I was playing around with multicast on 9front the other week and
managed to get something working (for some definition of working). I
have attached 2 test programs for sending and receiving multicast
datagrams. Unfortunately, it seems you can't send/receive messages
from the same host. I'm not sure what's missing to get that part
working.
Also, note that the dial in mcastrecv.c is just a hack to get the
local address via getnetconninfo, which doesn't seem to work given the
announce directory.
Hopefully these are of some use. Would be interested to hear how to
fix the mentioned (and unmentioned) shortcomings.
--
Cheers,
Alex Musolino
#include <u.h>
#include <libc.h>
static void
usage(void)
{
print("usage: %s mcast-ip port\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
NetConnInfo *ncinfo;
char adir[40], ldir[40], buf[1024];
int fd, acfd, lcfd, dfd, n;
ARGBEGIN{
default:
usage();
}ARGEND;
if(argc != 2)
usage();
fd = dial(netmkaddr(argv[0], "udp", argv[1]), 0, 0, 0);
ncinfo = getnetconninfo(nil, fd);
if(ncinfo == nil)
sysfatal("getnetconninfo: %r");
close(fd);
acfd = announce(netmkaddr(argv[0], "udp", argv[1]), adir);
if(acfd < 0)
sysfatal("announce: %r");
if(fprint(acfd, "addmulti %s %s", ncinfo->lsys, argv[0]) < 0)
sysfatal("addmulti: %r");
freenetconninfo(ncinfo);
for(;;){
lcfd = listen(adir, ldir);
if(lcfd < 0)
sysfatal("listen: %r");
switch(fork()){
case -1:
sysfatal("fork: %r");
case 0:
dfd = accept(lcfd, ldir);
if(dfd < 0)
sysfatal("accept: %r");
if((n = read(dfd, buf, sizeof(buf))) < 0)
sysfatal("read: %r");
write(1, buf, n);
exits(0);
default:
close(lcfd);
}
}
}
#include <u.h>
#include <libc.h>
static void
usage(void)
{
print("usage: %s mcast-addr port\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
NetConnInfo *ncinfo;
char buf[1024];
int fd, cfd, n;
ARGBEGIN{
default:
usage();
}ARGEND;
if(argc != 2)
usage();
fd = dial(netmkaddr(argv[0], "udp", argv[1]), 0, 0, &cfd);
if(fd < 0)
sysfatal("dial: %r");
ncinfo = getnetconninfo(nil, fd);
if(ncinfo == nil)
sysfatal("getnetconninfo: %r");
if(fprint(cfd, "addmulti %s %s", ncinfo->lsys, argv[0]) < 0)
sysfatal("addmulti: %r");
freenetconninfo(ncinfo);
while((n = read(0, buf, sizeof(buf))) > 0)
write(fd, buf, n);
close(fd);
}
