mirror of
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55 lines
1.7 KiB
Go
55 lines
1.7 KiB
Go
/*
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Maddy Mail Server - Composable all-in-one email server.
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Copyright © 2019-2020 Max Mazurov <fox.cpp@disroot.org>, Maddy Mail Server contributors
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package dns
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import (
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"context"
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"net"
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"time"
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)
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var (
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overrideServ string
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)
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// override globally overrides the used DNS server address with one provided.
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// This function is meant only for testing. It should be called before any modules are
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// initialized to have full effect.
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//
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// The server argument is in form of "IP:PORT". It is expected that the server
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// will be available both using TCP and UDP on the same port.
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func override(server string) {
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net.DefaultResolver.PreferGo = true
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net.DefaultResolver.Dial = func(ctx context.Context, network, address string) (net.Conn, error) {
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dialer := net.Dialer{
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// This is localhost, it is either running or not. Fail quickly if
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// we can't connect.
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Timeout: 1 * time.Second,
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}
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switch network {
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case "udp", "udp4", "udp6":
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return dialer.DialContext(ctx, "udp4", server)
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case "tcp", "tcp4", "tcp6":
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return dialer.DialContext(ctx, "tcp4", server)
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default:
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panic("OverrideDNS.Dial: unknown network")
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}
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}
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}
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