~samwhited/xmpp

ref: 52be89df867be9fc4e8ba83b0c3880887a6485ba xmpp/dial.go -rw-r--r-- 3.9 KiB
52be89dfSam Whited form: Rename Option and FieldOption types 4 years ago
                                                                                
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
// Copyright 2016 Sam Whited.
// Use of this source code is governed by the BSD 2-clause license that can be
// found in the LICENSE file.

package xmpp

import (
	"context"
	"net"
	"strconv"
	"time"

	"mellium.im/xmpp/jid"
)

// Conn is a net.Conn created for the purpose of establishing an XMPP session.
type Conn net.Conn

// DialClient discovers and connects to the address on the named network with a
// client-to-server (c2s) connection.
//
// If the context expires before the connection is complete, an error is
// returned. Once successfully connected, any expiration of the context will not
// affect the connection.
//
// addr is a JID with a domainpart of the server we wish to connect too.
// DialClient will attempt to look up SRV records for the given JIDs domainpart
// or connect to the domainpart directly.
//
// Network may be any of the network types supported by net.Dial, but you almost
// certainly want to use one of the tcp connection types ("tcp", "tcp4", or
// "tcp6").
func DialClient(ctx context.Context, network string, addr *jid.JID) (Conn, error) {
	var d Dialer
	return d.Dial(ctx, network, addr)
}

// DialServer discovers and connects to the address on the named network with a
// server-to-server connection (s2s).
//
// For more info see the DialClient function.
func DialServer(ctx context.Context, network string, addr *jid.JID) (Conn, error) {
	d := Dialer{
		S2S: true,
	}
	return d.Dial(ctx, network, addr)
}

// A Dialer contains options for connecting to an XMPP address.
//
// The zero value for each field is equivalent to dialing without that option.
// Dialing with the zero value of Dialer is therefore equivalent to just calling
// the DialClient function.
type Dialer struct {
	net.Dialer

	// NoLookup stops the dialer from looking up SRV or TXT records for the given
	// domain. It also prevents fetching of the host metadata file.
	// Instead, it will try to connect to the domain directly.
	NoLookup bool

	// Attempt to dial a server-to-server connection.
	S2S bool
}

// Dial discovers and connects to the address on the named network.
//
// For a description of the arguments see the DialClient function.
func (d *Dialer) Dial(ctx context.Context, network string, addr *jid.JID) (Conn, error) {
	return d.dial(ctx, network, addr)
}

func (d *Dialer) dial(ctx context.Context, network string, addr *jid.JID) (Conn, error) {
	if d.NoLookup {
		p, err := lookupPort(network, connType(d.S2S))
		if err != nil {
			return nil, err
		}
		return d.Dialer.DialContext(ctx, network, net.JoinHostPort(
			addr.Domainpart(),
			strconv.FormatUint(uint64(p), 10),
		))
	}

	addrs, err := lookupService(connType(d.S2S), network, addr)
	if err != nil {
		return nil, err
	}

	// Try dialing all of the SRV records we know about, breaking as soon as the
	// connection is established.
	for _, addr := range addrs {
		conn, e := d.Dialer.DialContext(
			ctx, network, net.JoinHostPort(
				addr.Target, strconv.FormatUint(uint64(addr.Port), 10),
			),
		)
		if e != nil {
			err = e
			continue
		}

		return conn, nil
	}
	return nil, err
}

// Copied from the net package in the standard library. Copyright The Go
// Authors.
func minNonzeroTime(a, b time.Time) time.Time {
	if a.IsZero() {
		return b
	}
	if b.IsZero() || a.Before(b) {
		return a
	}
	return b
}

// Copied from the net package in the standard library. Copyright The Go
// Authors.
//
// deadline returns the earliest of:
//   - now+Timeout
//   - d.Deadline
//   - the context's deadline
// Or zero, if none of Timeout, Deadline, or context's deadline is set.
func (d *Dialer) deadline(ctx context.Context, now time.Time) (earliest time.Time) {
	if d.Timeout != 0 { // including negative, for historical reasons
		earliest = now.Add(d.Timeout)
	}
	if d, ok := ctx.Deadline(); ok {
		earliest = minNonzeroTime(earliest, d)
	}
	return minNonzeroTime(earliest, d.Deadline)
}

func connType(s2s bool) string {
	if s2s {
		return "xmpp-server"
	}
	return "xmpp-client"
}