xnet: Networker += Name()

Networker.Name should return name of access-point Networker represents
on the network.

We will need this information in the next patch for tracing dial events,
when there is no connection established yet, and thus dialer location
has to be taken from somewhere. It is also generally a good idea for
Networker to have a name.

For NetPlain networker the name is local hostname.

xnet/net.go

-// Copyright (C) 2017  Nexedi SA and Contributors.
-//                     Kirill Smelkov <kirr@nexedi.com>
+// Copyright (C) 2017-2018  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
 // it under the terms of the GNU General Public License version 3, or (at your
@@ -22,7 +22,9 @@ package xnet
 
 import (
 	"context"
+	"fmt"
 	"net"
+	"os"
 
 	"crypto/tls"
 )
@@ -32,6 +34,9 @@ type Networker interface {
 	// Network returns name of the network
 	Network() string
 
+	// Name returns name of the access-point on the network
+	Name() string
+
 	// XXX +Addr() net.Addr	 -> address of this access-point on underlying network ?
 
 	// Dial connects to addr on underlying network
@@ -46,26 +51,41 @@ type Networker interface {
 }
 
 
+var hostname string
+func init() {
+	host, err := os.Hostname()
+	if err != nil {
+		panic(fmt.Errorf("cannot detect hostname: %s", err))
+	}
+	hostname = host
+}
+
 // NetPlain creates Networker corresponding to regular network accessors from std package net.
 //
 // network is "tcp", "tcp4", "tcp6", "unix", etc...
 func NetPlain(network string) Networker {
-	return netPlain(network)
+	return &netPlain{network, hostname}
 }
 
-type netPlain string
+type netPlain struct {
+	network, hostname string
+}
+
+func (n *netPlain) Network() string {
+	return n.network
+}
 
-func (n netPlain) Network() string {
-	return string(n)
+func (n *netPlain) Name() string {
+	return n.hostname
 }
 
-func (n netPlain) Dial(ctx context.Context, addr string) (net.Conn, error) {
+func (n *netPlain) Dial(ctx context.Context, addr string) (net.Conn, error) {
 	d := net.Dialer{}
-	return d.DialContext(ctx, string(n), addr)
+	return d.DialContext(ctx, n.network, addr)
 }
 
-func (n netPlain) Listen(laddr string) (net.Listener, error) {
-	return net.Listen(string(n), laddr)
+func (n *netPlain) Listen(laddr string) (net.Listener, error) {
+	return net.Listen(n.network, laddr)
 }
 
 // NetTLS wraps underlying networker with TLS layer according to config.
@@ -86,6 +106,10 @@ func (n *netTLS) Network() string {
 	return n.inner.Network() + "+tls"
 }
 
+func (n *netTLS) Name() string {
+	return n.inner.Name()
+}
+
 func (n *netTLS) Dial(ctx context.Context, addr string) (net.Conn, error) {
 	c, err := n.inner.Dial(ctx, addr)
 	if err != nil {

xnet/pipenet/pipenet.go

-// Copyright (C) 2017  Nexedi SA and Contributors.
-//                     Kirill Smelkov <kirr@nexedi.com>
+// Copyright (C) 2017-2018  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
 // it under the terms of the GNU General Public License version 3, or (at your
@@ -424,3 +424,6 @@ func (n *Network) Network() string { return NetPrefix + n.name }
 
 // Network returns full network name of underlying network
 func (h *Host) Network() string { return h.network.Network() }
+
+// Name returns host name.
+func (h *Host) Name() string { return h.name }

xnet/pipenet/pipenet_test.go

@@ -101,6 +101,8 @@ func TestPipeNet(t *testing.T) {
 
 	assertEq(t, hα.Network(), "pipet")
 	assertEq(t, hβ.Network(), "pipet")
+	assertEq(t, hα.Name(), "α")
+	assertEq(t, hβ.Name(), "β")
 
 	_, err := hα.Dial(context.Background(), ":0")
 	assertEq(t, err, &net.OpError{Op: "dial", Net: "pipet", Addr: xaddr("α:0"), Err: errConnRefused})

xnet/trace.go

-// Copyright (C) 2017  Nexedi SA and Contributors.
-//                     Kirill Smelkov <kirr@nexedi.com>
+// Copyright (C) 2017-2018  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
 // it under the terms of the GNU General Public License version 3, or (at your
@@ -83,6 +83,10 @@ func (nt *netTrace) Network() string {
 	return nt.inner.Network() // XXX + "+trace" ?
 }
 
+func (nt *netTrace) Name() string {
+	return nt.inner.Name()
+}
+
 func (nt *netTrace) Dial(ctx context.Context, addr string) (net.Conn, error) {
 	// XXX +TraceNetDialPost ?
 	c, err := nt.inner.Dial(ctx, addr)