Re: [PATCH v2 01/10] SUNRPC: add AF_VSOCK support to addr.[ch]

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, May 22, 2017 at 08:54:56AM -0400, Jeff Layton wrote:
> On Mon, 2017-05-22 at 13:21 +0100, Stefan Hajnoczi wrote:
> > On Thu, May 18, 2017 at 10:04:24AM -0400, Jeff Layton wrote:
> > > On Fri, 2016-10-07 at 11:01 +0100, Stefan Hajnoczi wrote:
> > > > @@ -249,6 +302,10 @@ size_t rpc_pton(struct net *net, const char *buf, const size_t buflen,
> > > >  {
> > > >  	unsigned int i;
> > > >  
> > > > +	/* TODO is there a nicer way to distinguish vsock addresses? */
> > > > +	if (strncmp(buf, "vsock:", 6) == 0)
> > > > +		return rpc_pton_vsock(buf, buflen, sap, salen);
> > > > +
> > > 
> > > Ick, what if I have a host on the network named "vsock"? I think you'll
> > > need to come up with a different way to do this.
> > 
> > There is no collision.  This function doesn't do name resolution and no
> > valid IPv4/IPv6 address starts with "vsock:".
> > 
> 
> Doh! Of course... :)
> 
> > I am open to suggestions for a cleaner way of doing it though :).
> 
> Does lsof recognize vsock sockets? How does it format them?

lsof only prints a generic socket representation:

COMMAND     PID   TID       USER   FD      TYPE             DEVICE  SIZE/OFF       NODE NAME
nc-vsock  20775         stefanha    3u     sock                0,9       0t0    1518648 protocol: AF_VSOCK

Depending on a program's command-line syntax, addresses are usually
written as CID:PORT, or vsock:CID:PORT if the program must differentiate
between address types from the string itself.

QEMU, qemu-guest-agent, and systemd have syntax for specifying AF_VSOCK
sockets.  For example:
https://github.com/systemd/systemd/blob/master/src/test/test-socket-util.c#L98

If I have time to submit lsof patches I'll propose the following syntax
(a combination of how AF_UNIX and AF_INET TCP sockets are formatted):

COMMAND     PID   TID       USER   FD      TYPE             DEVICE  SIZE/OFF       NODE NAME
nc-vsock  20775         stefanha    3u     vsock           1520136       0t0    1520136 local=2:1234 state=LISTEN type=STREAM
nc-vsock  20775         stefanha    4u     vsock           1520138       0t0    1520138 local=2:1234 remote=3:51213 state=CONNECTED type=STREAM

Stefan

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