1// Copyright (c) 2013-2014 The btcsuite developers
2// Use of this source code is governed by an ISC
3// license that can be found in the LICENSE file.
4
5package addrmgr
6
7import (
8	"time"
9
10	"github.com/btcsuite/btcd/wire"
11)
12
13// KnownAddress tracks information about a known network address that is used
14// to determine how viable an address is.
15type KnownAddress struct {
16	na          *wire.NetAddress
17	srcAddr     *wire.NetAddress
18	attempts    int
19	lastattempt time.Time
20	lastsuccess time.Time
21	tried       bool
22	refs        int // reference count of new buckets
23}
24
25// NetAddress returns the underlying wire.NetAddress associated with the
26// known address.
27func (ka *KnownAddress) NetAddress() *wire.NetAddress {
28	return ka.na
29}
30
31// LastAttempt returns the last time the known address was attempted.
32func (ka *KnownAddress) LastAttempt() time.Time {
33	return ka.lastattempt
34}
35
36// Services returns the services supported by the peer with the known address.
37func (ka *KnownAddress) Services() wire.ServiceFlag {
38	return ka.na.Services
39}
40
41// chance returns the selection probability for a known address.  The priority
42// depends upon how recently the address has been seen, how recently it was last
43// attempted and how often attempts to connect to it have failed.
44func (ka *KnownAddress) chance() float64 {
45	now := time.Now()
46	lastAttempt := now.Sub(ka.lastattempt)
47
48	if lastAttempt < 0 {
49		lastAttempt = 0
50	}
51
52	c := 1.0
53
54	// Very recent attempts are less likely to be retried.
55	if lastAttempt < 10*time.Minute {
56		c *= 0.01
57	}
58
59	// Failed attempts deprioritise.
60	for i := ka.attempts; i > 0; i-- {
61		c /= 1.5
62	}
63
64	return c
65}
66
67// isBad returns true if the address in question has not been tried in the last
68// minute and meets one of the following criteria:
69// 1) It claims to be from the future
70// 2) It hasn't been seen in over a month
71// 3) It has failed at least three times and never succeeded
72// 4) It has failed ten times in the last week
73// All addresses that meet these criteria are assumed to be worthless and not
74// worth keeping hold of.
75func (ka *KnownAddress) isBad() bool {
76	if ka.lastattempt.After(time.Now().Add(-1 * time.Minute)) {
77		return false
78	}
79
80	// From the future?
81	if ka.na.Timestamp.After(time.Now().Add(10 * time.Minute)) {
82		return true
83	}
84
85	// Over a month old?
86	if ka.na.Timestamp.Before(time.Now().Add(-1 * numMissingDays * time.Hour * 24)) {
87		return true
88	}
89
90	// Never succeeded?
91	if ka.lastsuccess.IsZero() && ka.attempts >= numRetries {
92		return true
93	}
94
95	// Hasn't succeeded in too long?
96	if !ka.lastsuccess.After(time.Now().Add(-1*minBadDays*time.Hour*24)) &&
97		ka.attempts >= maxFailures {
98		return true
99	}
100
101	return false
102}
103