bch 0.1.1

A Rust library for working with Bitcoin Cash
Documentation 
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
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227

use util::{Error, Result};

/// Pops a bool off the stack
#[inline]
pub fn pop_bool(stack: &mut Vec<Vec<u8>>) -> Result<bool> {
    if stack.len() == 0 {
        let msg = "Cannot pop bool, empty stack".to_string();
        return Err(Error::ScriptError(msg));
    }
    let top = stack.pop().unwrap();
    // Bools cannot be popped having more than 32-bits, but may be used in other ways
    if top.len() > 4 {
        let msg = format!("Cannot pop bool, len too long {}", top.len());
        return Err(Error::ScriptError(msg));
    }
    Ok(decode_bool(&top))
}

/// Pops a number off the stack
#[inline]
pub fn pop_num(stack: &mut Vec<Vec<u8>>) -> Result<i32> {
    if stack.len() == 0 {
        let msg = "Cannot pop num, empty stack".to_string();
        return Err(Error::ScriptError(msg));
    }
    let top = stack.pop().unwrap();
    // Numbers cannot be popped having more than 4 bytes, but may overflow on the stack to 5 bytes
    // after certain operations and may be used as byte vectors.
    if top.len() > 4 {
        let msg = format!("Cannot pop num, len too long {}", top.len());
        return Err(Error::ScriptError(msg));
    }
    Ok(decode_num(&top)? as i32)
}

/// Converts a stack item to a bool
#[inline]
pub fn decode_bool(s: &[u8]) -> bool {
    if s.len() == 0 {
        return false;
    }
    for i in 0..s.len() - 1 {
        if s[i] != 0 {
            return true;
        }
    }
    s[s.len() - 1] & 127 != 0
}

/// Converts a stack item to a number
#[inline]
pub fn decode_num(s: &[u8]) -> Result<i64> {
    let mut val = match s.len() {
        0 => return Ok(0),
        1 => (s[0] & 127) as i64,
        2 => (((s[1] & 127) as i64) << 8) + ((s[0] as i64) << 0),
        3 => (((s[2] & 127) as i64) << 16) + ((s[1] as i64) << 8) + ((s[0] as i64) << 0),
        4 => {
            (((s[3] & 127) as i64) << 24)
                + ((s[2] as i64) << 16)
                + ((s[1] as i64) << 8)
                + ((s[0] as i64) << 0)
        }
        _ => {
            for i in 4..s.len() - 1 {
                if s[i] != 0 {
                    return Err(Error::ScriptError("Number too big".to_string()));
                }
            }
            if s[s.len() - 1] & 127 != 0 {
                return Err(Error::ScriptError("Number too big".to_string()));
            }
            ((s[3] as i64) << 24)
                + ((s[2] as i64) << 16)
                + ((s[1] as i64) << 8)
                + ((s[0] as i64) << 0)
        }
    };
    if s[s.len() - 1] & 128 != 0 {
        val = 0 - val;
    }
    Ok(val)
}

/// Converts a number to a 32-bit stack item
#[inline]
pub fn encode_num(val: i64) -> Result<Vec<u8>> {
    // Range: [-2^31+1, 2^31-1]
    if val > 2147483647 || val < -2147483647 {
        return Err(Error::ScriptError("Number out of range".to_string()));
    }
    let (posval, negmask) = if val < 0 { (-val, 128) } else { (val, 0) };
    if posval == 0 {
        Ok(vec![])
    } else if posval < 128 {
        Ok(vec![(posval as u8) | negmask])
    } else if posval < 32768 {
        Ok(vec![(posval >> 0) as u8, ((posval >> 8) as u8) | negmask])
    } else if posval < 8388608 {
        Ok(vec![
            (posval >> 0) as u8,
            (posval >> 8) as u8,
            ((posval >> 16) as u8) | negmask,
        ])
    } else {
        Ok(vec![
            (posval >> 0) as u8,
            (posval >> 8) as u8,
            (posval >> 16) as u8,
            ((posval >> 24) as u8) | negmask,
        ])
    }
}

/// Converts a number to a stack item, allowing for overflow to 5 bytes
#[inline]
pub fn encode_num_overflow(val: i64) -> Result<Vec<u8>> {
    // Range: [-2^31+1 -2^31+1, 2^31-1 + 2^31-1]
    if val > 4294967294 || val < -4294967294 {
        return Err(Error::ScriptError("Number out of range".to_string()));
    }
    let (posval, negmask) = if val < 0 { (-val, 128) } else { (val, 0) };
    if posval <= 2147483647 {
        encode_num(val)
    } else {
        Ok(vec![
            (posval >> 0) as u8,
            (posval >> 8) as u8,
            (posval >> 16) as u8,
            (posval >> 24) as u8,
            ((posval >> 32) as u8) | negmask,
        ])
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn decode_bool_tests() {
        assert!(decode_bool(&[1]) == true);
        assert!(decode_bool(&[255, 0, 0, 0]) == true);
        assert!(decode_bool(&[0, 0, 0, 129]) == true);
        assert!(decode_bool(&[0]) == false);
        assert!(decode_bool(&[0, 0, 0, 0]) == false);
        assert!(decode_bool(&[0, 0, 0, 128]) == false);
        assert!(decode_bool(&[]) == false);
    }

    #[test]
    fn pop_bool_tests() {
        assert!(pop_bool(&mut vec![vec![1]]).unwrap() == true);
        assert!(pop_bool(&mut vec![vec![0, 0, 0, 127]]).unwrap() == true);
        assert!(pop_bool(&mut vec![vec![0, 0, 0, 127]]).unwrap() == true);
        assert!(pop_bool(&mut vec![]).is_err());
        assert!(pop_bool(&mut vec![vec![0, 0, 0, 0, 0]]).is_err());
        assert!(pop_bool(&mut vec![vec![]]).unwrap() == false);
        assert!(pop_bool(&mut vec![vec![0]]).unwrap() == false);
        assert!(pop_bool(&mut vec![vec![0, 0, 0, 0]]).unwrap() == false);
        assert!(pop_bool(&mut vec![vec![0, 0, 0, 128]]).unwrap() == false);
    }

    #[test]
    fn encode_decode_num_tests() {
        // Range checks
        assert!(encode_num(2147483647).is_ok());
        assert!(encode_num(-2147483647).is_ok());
        assert!(encode_num(2147483648).is_err());
        assert!(encode_num(-2147483648).is_err());
        assert!(encode_num_overflow(4294967294).is_ok());
        assert!(encode_num_overflow(-4294967294).is_ok());
        assert!(encode_num_overflow(4294967295).is_err());
        assert!(encode_num_overflow(-4294967295).is_err());
        // Encode decode
        assert!(decode_num(&encode_num(0).unwrap()).unwrap() == 0);
        assert!(decode_num(&encode_num(1).unwrap()).unwrap() == 1);
        assert!(decode_num(&encode_num(-1).unwrap()).unwrap() == -1);
        assert!(decode_num(&encode_num(1111).unwrap()).unwrap() == 1111);
        assert!(decode_num(&encode_num(-1111).unwrap()).unwrap() == -1111);
        assert!(decode_num(&encode_num(111111).unwrap()).unwrap() == 111111);
        assert!(decode_num(&encode_num(-111111).unwrap()).unwrap() == -111111);
        assert!(decode_num(&encode_num(2147483647).unwrap()).unwrap() == 2147483647);
        assert!(decode_num(&encode_num(-2147483647).unwrap()).unwrap() == -2147483647);
        // Encode decode with overflow
        assert!(decode_num(&encode_num_overflow(0).unwrap()).unwrap() == 0);
        assert!(decode_num(&encode_num_overflow(1).unwrap()).unwrap() == 1);
        assert!(decode_num(&encode_num_overflow(-1).unwrap()).unwrap() == -1);
        assert!(decode_num(&encode_num_overflow(1111).unwrap()).unwrap() == 1111);
        assert!(decode_num(&encode_num_overflow(-1111).unwrap()).unwrap() == -1111);
        assert!(decode_num(&encode_num_overflow(111111).unwrap()).unwrap() == 111111);
        assert!(decode_num(&encode_num_overflow(-111111).unwrap()).unwrap() == -111111);
        assert!(decode_num(&encode_num_overflow(2147483647).unwrap()).unwrap() == 2147483647);
        assert!(decode_num(&encode_num_overflow(-2147483647).unwrap()).unwrap() == -2147483647);
        assert!(decode_num(&encode_num_overflow(4294967294).unwrap()).unwrap() == 4294967294);
        assert!(decode_num(&encode_num_overflow(-4294967294).unwrap()).unwrap() == -4294967294);
        // Minimum lengths
        assert!(encode_num_overflow(0).unwrap().len() == 0);
        assert!(encode_num_overflow(1).unwrap().len() == 1);
        assert!(encode_num_overflow(-1).unwrap().len() == 1);
        assert!(encode_num_overflow(127).unwrap().len() == 1);
        assert!(encode_num_overflow(-127).unwrap().len() == 1);
        assert!(encode_num_overflow(128).unwrap().len() == 2);
        assert!(encode_num_overflow(-128).unwrap().len() == 2);
        assert!(encode_num_overflow(32767).unwrap().len() == 2);
        assert!(encode_num_overflow(-32767).unwrap().len() == 2);
        assert!(encode_num_overflow(32768).unwrap().len() == 3);
        assert!(encode_num_overflow(-32768).unwrap().len() == 3);
        assert!(encode_num_overflow(8388607).unwrap().len() == 3);
        assert!(encode_num_overflow(-8388607).unwrap().len() == 3);
        assert!(encode_num_overflow(8388608).unwrap().len() == 4);
        assert!(encode_num_overflow(-8388608).unwrap().len() == 4);
        assert!(encode_num_overflow(2147483647).unwrap().len() == 4);
        assert!(encode_num_overflow(-2147483647).unwrap().len() == 4);
        assert!(encode_num_overflow(2147483648).unwrap().len() == 5);
        assert!(encode_num_overflow(-2147483648).unwrap().len() == 5);
    }

    #[test]
    fn pop_num_tests() {
        assert!(pop_num(&mut vec![vec![]]).unwrap() == 0);
        assert!(pop_num(&mut vec![vec![1]]).unwrap() == 1);
        assert!(pop_num(&mut vec![vec![129]]).unwrap() == -1);
        assert!(pop_num(&mut vec![vec![0, 0, 0, 0]]).unwrap() == 0);
        assert!(pop_num(&mut vec![vec![0, 0, 0, 0, 0]]).is_err());
    }
}