aboutsummaryrefslogtreecommitdiffstats
path: root/swarm/pot/address.go
blob: 75c2994ec067978236dc0c36d68ce0a38b5f1cad (plain) (blame)
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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package pot see doc.go
package pot

import (
    "encoding/binary"
    "fmt"
    "math/rand"
    "strconv"
    "strings"

    "github.com/dexon-foundation/dexon/common"
)

var (
    zerosBin = Address{}.Bin()
)

// Address is an alias for common.Hash
type Address common.Hash

// NewAddressFromBytes constructs an Address from a byte slice
func NewAddressFromBytes(b []byte) Address {
    h := common.Hash{}
    copy(h[:], b)
    return Address(h)
}

func (a Address) String() string {
    return fmt.Sprintf("%x", a[:])
}

// MarshalJSON Address serialisation
func (a *Address) MarshalJSON() (out []byte, err error) {
    return []byte(`"` + a.String() + `"`), nil
}

// UnmarshalJSON Address deserialisation
func (a *Address) UnmarshalJSON(value []byte) error {
    *a = Address(common.HexToHash(string(value[1 : len(value)-1])))
    return nil
}

// Bin returns the string form of the binary representation of an address (only first 8 bits)
func (a Address) Bin() string {
    return ToBin(a[:])
}

// ToBin converts a byteslice to the string binary representation
func ToBin(a []byte) string {
    var bs []string
    for _, b := range a {
        bs = append(bs, fmt.Sprintf("%08b", b))
    }
    return strings.Join(bs, "")
}

// Bytes returns the Address as a byte slice
func (a Address) Bytes() []byte {
    return a[:]
}

// ProxCmp compares the distances a->target and b->target.
// Returns -1 if a is closer to target, 1 if b is closer to target
// and 0 if they are equal.
func ProxCmp(a, x, y interface{}) int {
    return proxCmp(ToBytes(a), ToBytes(x), ToBytes(y))
}

func proxCmp(a, x, y []byte) int {
    for i := range a {
        dx := x[i] ^ a[i]
        dy := y[i] ^ a[i]
        if dx > dy {
            return 1
        } else if dx < dy {
            return -1
        }
    }
    return 0
}

// RandomAddressAt (address, prox) generates a random address
// at proximity order prox relative to address
// if prox is negative a random address is generated
func RandomAddressAt(self Address, prox int) (addr Address) {
    addr = self
    pos := -1
    if prox >= 0 {
        pos = prox / 8
        trans := prox % 8
        transbytea := byte(0)
        for j := 0; j <= trans; j++ {
            transbytea |= 1 << uint8(7-j)
        }
        flipbyte := byte(1 << uint8(7-trans))
        transbyteb := transbytea ^ byte(255)
        randbyte := byte(rand.Intn(255))
        addr[pos] = ((addr[pos] & transbytea) ^ flipbyte) | randbyte&transbyteb
    }
    for i := pos + 1; i < len(addr); i++ {
        addr[i] = byte(rand.Intn(255))
    }

    return
}

// RandomAddress generates a random address
func RandomAddress() Address {
    return RandomAddressAt(Address{}, -1)
}

// NewAddressFromString creates a byte slice from a string in binary representation
func NewAddressFromString(s string) []byte {
    ha := [32]byte{}

    t := s + zerosBin[:len(zerosBin)-len(s)]
    for i := 0; i < 4; i++ {
        n, err := strconv.ParseUint(t[i*64:(i+1)*64], 2, 64)
        if err != nil {
            panic("wrong format: " + err.Error())
        }
        binary.BigEndian.PutUint64(ha[i*8:(i+1)*8], n)
    }
    return ha[:]
}

// BytesAddress is an interface for elements addressable by a byte slice
type BytesAddress interface {
    Address() []byte
}

// ToBytes turns the Val into bytes
func ToBytes(v Val) []byte {
    if v == nil {
        return nil
    }
    b, ok := v.([]byte)
    if !ok {
        ba, ok := v.(BytesAddress)
        if !ok {
            panic(fmt.Sprintf("unsupported value type %T", v))
        }
        b = ba.Address()
    }
    return b
}

// DefaultPof returns a proximity order comparison operator function
func DefaultPof(max int) func(one, other Val, pos int) (int, bool) {
    return func(one, other Val, pos int) (int, bool) {
        po, eq := proximityOrder(ToBytes(one), ToBytes(other), pos)
        if po >= max {
            eq = true
            po = max
        }
        return po, eq
    }
}

// proximityOrder returns two parameters:
// 1. relative proximity order of the arguments one & other;
// 2. boolean indicating whether the full match occurred (one == other).
func proximityOrder(one, other []byte, pos int) (int, bool) {
    for i := pos / 8; i < len(one); i++ {
        if one[i] == other[i] {
            continue
        }
        oxo := one[i] ^ other[i]
        start := 0
        if i == pos/8 {
            start = pos % 8
        }
        for j := start; j < 8; j++ {
            if (oxo>>uint8(7-j))&0x01 != 0 {
                return i*8 + j, false
            }
        }
    }
    return len(one) * 8, true
}

// Label displays the node's key in binary format
func Label(v Val) string {
    if v == nil {
        return "<nil>"
    }
    if s, ok := v.(fmt.Stringer); ok {
        return s.String()
    }
    if b, ok := v.([]byte); ok {
        return ToBin(b)
    }
    panic(fmt.Sprintf("unsupported value type %T", v))
}