go/neo/neonet += Join

The utility to create Networker suitable for interoperating with nodes
in a NEO cluster, be it TCP, TLS/TCP, TLS/lonet, etc. See added comments
for details.

go/neo/neonet/connection.go

@@ -59,6 +59,14 @@
 // connection. A response can be sent back via Request.Reply. Then once
 // Request.Close is called the connection object that was accepted is
 // immediately put back into pool for later reuse.
+//
+//
+// Joining network
+//
+// Besides plain TCP, NEO clusters are frequently configured to use TLS in
+// peer-to-peer mode and/or network virtualisation. A networker suitable for
+// interoperating with nodes in such a cluster can be created via Join. See
+// Join and Config for details.
 package neonet
 
 // XXX neonet compatibility with NEO/py depends on the following small NEO/py patch:

go/neo/neonet/net.go

+// Copyright (C) 2018-2020  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
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package neonet
+// joining raw underlying network.
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"lab.nexedi.com/kirr/go123/xerr"
+	"lab.nexedi.com/kirr/go123/xnet"
+	"lab.nexedi.com/kirr/go123/xnet/lonet"
+	"lab.nexedi.com/kirr/go123/xstrings"
+
+	"lab.nexedi.com/kirr/neo/go/neo/internal/xtls"
+)
+
+
+// Config specifies network configuration for Join.
+//
+// Empty config means to use plain TCP networking for inter-node exchange.
+type Config struct {
+	// CA/Cert/Key, if non-empty, tells to use TLS in peer-to-peer mode
+	// with CA certificate and public/private node keys taken from specified files.
+	CA, Cert, Key string
+
+	// LoNode, if non-empty, tells to use lonet as underlying network.
+	// Network and hostname should be specified as "<net>/<host>".
+	LoNode string
+}
+
+
+// Join returns network access-point suitable for interoperating with nodes in
+// a NEO cluster according to config.
+func Join(ctx context.Context, cfg Config) (net xnet.Networker, err error) {
+	optv := []string{}
+	ssl := (cfg.CA != "" || cfg.Cert != "" || cfg.Key != "")
+	if ssl {
+		optv = append(optv, "ssl")
+	}
+	if cfg.LoNode != "" {
+		optv = append(optv, fmt.Sprintf("lonode=%q", cfg.LoNode))
+	}
+	defer xerr.Contextf(&err, "neonet join [%s]", strings.Join(optv, " "))
+
+	if ssl && !(cfg.CA != "" && cfg.Cert != "" && cfg.Key != "") {
+		return nil, fmt.Errorf("incomplete ca/cert/key provided")
+	}
+
+	defer func() {
+		if err != nil && net != nil {
+			net.Close() // ignore err
+		}
+	}()
+
+	if cfg.LoNode == "" {
+		net = xnet.NetPlain("tcp") // TODO not only "tcp" ?
+	} else {
+		netname, hostname, err := xstrings.HeadTail(cfg.LoNode, "/")
+		if err != nil {
+			return nil, fmt.Errorf("invalid lonode")
+		}
+		network, err := lonet.Join(ctx, netname)
+		if err != nil {
+			return nil, err
+		}
+		host, err := network.NewHost(ctx, hostname)
+		if err != nil {
+			network.Close() // ignore err
+			return nil, err
+		}
+		network.AutoClose() // host.Close will close network
+
+		net = host
+	}
+
+	if ssl {
+		tlsCfg, err := xtls.ConfigForP2P(cfg.CA, cfg.Cert, cfg.Key)
+		if err != nil {
+			return nil, err
+		}
+		net = xnet.NetTLS(net, tlsCfg)
+	}
+
+	return net, nil
+}