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8096441f67
the default transport is still just "direct delivery", where we connect to the destination domain's MX servers. other transports are: - regular smtp without authentication, this is relaying to a smarthost. - submission with authentication, e.g. to a third party email sending service. - direct delivery, but with with connections going through a socks proxy. this can be helpful if your ip is blocked, you need to get email out, and you have another IP that isn't blocked. keep in mind that for all of the above, appropriate SPF/DKIM settings have to be configured. the "dnscheck" for a domain does a check for any SOCKS IP in the SPF record. SPF for smtp/submission (ranges? includes?) and any DKIM requirements cannot really be checked. which transport is used can be configured through routes. routes can be set on an account, a domain, or globally. the routes are evaluated in that order, with the first match selecting the transport. these routes are evaluated for each delivery attempt. common selection criteria are recipient domain and sender domain, but also which delivery attempt this is. you could configured mox to attempt sending through a 3rd party from the 4th attempt onwards. routes and transports are optional. if no route matches, or an empty/zero transport is selected, normal direct delivery is done. we could already "submit" emails with 3rd party accounts with "sendmail". but we now support more SASL authentication mechanisms with SMTP (not only PLAIN, but also SCRAM-SHA-256, SCRAM-SHA-1 and CRAM-MD5), which sendmail now also supports. sendmail will use the most secure mechanism supported by the server, or the explicitly configured mechanism. for issue #36 by dmikushin. also based on earlier discussion on hackernews.
54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proxy
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import (
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"context"
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"net"
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)
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// A ContextDialer dials using a context.
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type ContextDialer interface {
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DialContext(ctx context.Context, network, address string) (net.Conn, error)
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}
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// Dial works like DialContext on net.Dialer but using a dialer returned by FromEnvironment.
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//
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// The passed ctx is only used for returning the Conn, not the lifetime of the Conn.
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//
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// Custom dialers (registered via RegisterDialerType) that do not implement ContextDialer
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// can leak a goroutine for as long as it takes the underlying Dialer implementation to timeout.
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//
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// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
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func Dial(ctx context.Context, network, address string) (net.Conn, error) {
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d := FromEnvironment()
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if xd, ok := d.(ContextDialer); ok {
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return xd.DialContext(ctx, network, address)
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}
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return dialContext(ctx, d, network, address)
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}
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// WARNING: this can leak a goroutine for as long as the underlying Dialer implementation takes to timeout
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// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
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func dialContext(ctx context.Context, d Dialer, network, address string) (net.Conn, error) {
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var (
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conn net.Conn
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done = make(chan struct{}, 1)
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err error
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)
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go func() {
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conn, err = d.Dial(network, address)
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close(done)
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if conn != nil && ctx.Err() != nil {
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conn.Close()
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}
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}()
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select {
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case <-ctx.Done():
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err = ctx.Err()
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case <-done:
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}
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return conn, err
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}
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