Comment 1 by graycardinalster:

src/pkg/net/udpsock.go:76
The fourth argument should be the _pointer_ on a variable containing 1

Comment 2 by graycardinalster:

C version
int setBroadcast (int fd) 
{
    int one = 1;
    return setsockopt (fd, SOL_SOCKET, SO_BROADCAST, &one, 4);
}

Comment 3:

The pointer part isn't the problem.  udpsock calls setsockoptInt,
which (in syscall/syscall_linux.go's SetsockoptInt) does in fact
pass a pointer to the system call.
I don't know what the problem is, though.  If you'd like to
investigate the source is in src/pkg/net and src/pkg/syscall.

Owner changed to r...@golang.org.

Status changed to HelpWanted.

Comment 4 by dean.prichard:

I took a quick look, and for what it is worth, I get the above error only if 
ServerUDPaddr is not the broadcast for my local network. If it is, I don't see a
runtime error.

Comment 5 by graycardinalster:

However the example does not work for me if to specify broadcast the address.
192.168.111.2 - works. 192.168.111.255 - not  
OS Linux RedFlag

Comment 6 by graycardinalster:

Mmm.............
_,err = net.ListenUDP("udp4", laddr)
work :)

Comment 7 by graycardinalster:

broken_bcast2.go:
dial udp4 192.168.111.255:666: permission denied

Attachments:

1. broken_bcast2.go (345 bytes)

Comment 8 by dean.prichard:

This seems to be linux specific.
for broken_bcast2.go strace suggests that this error is  
because connect() is called before SO_BROADCAST is set.
this is probably not the best solution, but you could try:
--- a/src/pkg/net/sock.go   Sat Jan 09 09:47:45 2010 -0800
+++ b/src/pkg/net/sock.go   Sat Jan 16 01:43:42 2010 +0000
@@ -35,6 +35,9 @@
    // Allow reuse of recently-used addresses.
    syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
 
+   // For UDP Broadcasts on linux
+   setsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)
+
    if la != nil {
        e = syscall.Bind(s, la)
        if e != 0 {

Comment 9 by dean.prichard:

the following fixes it for me:
diff -r 1f997563b819 src/pkg/net/sock.go
--- a/src/pkg/net/sock.go   Fri Jan 15 14:02:53 2010 -0800
+++ b/src/pkg/net/sock.go   Sat Jan 16 07:56:41 2010 +0000
@@ -35,6 +35,11 @@
    // Allow reuse of recently-used addresses.
    syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
 
+   switch net {
+   case "udp", "udp4":
+       syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)
+   }
+
    if la != nil {
        e = syscall.Bind(s, la)
        if e != 0 {
diff -r 1f997563b819 src/pkg/net/udpsock.go
--- a/src/pkg/net/udpsock.go    Fri Jan 15 14:02:53 2010 -0800
+++ b/src/pkg/net/udpsock.go    Sat Jan 16 07:56:41 2010 +0000
@@ -71,11 +71,7 @@
    fd *netFD
 }
 
-func newUDPConn(fd *netFD) *UDPConn {
-   c := &UDPConn{fd}
-   setsockoptInt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)
-   return c
-}
+func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{fd} }
 
 func (c *UDPConn) ok() bool { return c != nil && c.fd != nil }

Comment 10 by graycardinalster:

Yes, it works. Thanks you.

Comment 11:

This issue was closed by revision 7c1bb00.

Status changed to Fixed.

Merged into issue #-.