Implemented the host name auto suggestion, and added Preset feature

application/network/dial_ac.go

@@ -0,0 +1,61 @@
+// Sshwifty - A Web SSH client
+//
+// Copyright (C) 2019-2020 Rui NI <nirui@gmx.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package network
+
+import (
+	"errors"
+	"net"
+	"time"
+)
+
+// Errors
+var (
+	ErrAccessControlDialTargetHostNotAllowed = errors.New(
+		"Refuse to connect to specified target host due to outgoing " +
+			"restriction")
+)
+
+// AllowedHosts contains a map of allowed remote hosts
+type AllowedHosts map[string]struct{}
+
+// Allowed returns whether or not given host is allowed
+func (a AllowedHosts) Allowed(host string) bool {
+	_, ok := a[host]
+
+	return ok
+}
+
+// AllowedHost returns whether or not give host is allowed
+type AllowedHost interface {
+	Allowed(host string) bool
+}
+
+// AccessControlDial creates an access controlled Dial
+func AccessControlDial(allowed AllowedHost, dial Dial) Dial {
+	return func(
+		network string,
+		address string,
+		timeout time.Duration,
+	) (net.Conn, error) {
+		if !allowed.Allowed(address) {
+			return nil, ErrAccessControlDialTargetHostNotAllowed
+		}
+
+		return dial(network, address, timeout)
+	}
+}