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

extern crate serde;
extern crate rand;
#[macro_use]
extern crate error_chain;

mod errors;

use std::result;

use serde::de::{self, Visitor};

pub use errors::{Error, ErrorKind, Result};

pub trait Checkable: Sized {
    const NAME: &'static str;
    fn check(key: &str) -> Result<Self>;
}


#[macro_export]
macro_rules! byte_seq {
    ($name:ident; $count:expr) => {

        #[derive(PartialOrd, Ord, PartialEq, Eq, Clone, Copy, Hash)]
        pub struct $name([u8; $count]);

        impl $crate::Checkable for $name {
            const NAME: &'static str = stringify!($name);
            fn check(key: &str) -> $crate::Result<$name> {
                ensure!(key.chars().count() == ($count * 2),
                       $crate::ErrorKind::InvalidKeyLen(key.to_string(), stringify!($name)));

                let mut bytes: [u8; $count] = [0u8; $count];
                for i in 0..$count {
                    if let Ok(byte) = u8::from_str_radix(&key[i*2..i*2+2], 16) {
                        bytes[i] = byte;
                    } else {
                        bail!($crate::ErrorKind::InvalidKeyChars(key.to_string(), stringify!($name)))
                    }
                }
                Ok($name(bytes))
            }

        }

        impl $name {

            pub fn generate_new() -> $name {
                use rand::thread_rng;
                use rand::Rng;

                let mut bytes: [u8; $count] = [0u8; $count];
                thread_rng().fill_bytes(&mut bytes);
                $name(bytes)
            }

            pub fn to_string(&self) -> String {
                let mut result = String::with_capacity($count * 2);
                for byte in &self.0 {
                    result.push_str(&format!("{:0width$X}", byte, width=2));
                }
                result
            }
        }

        impl std::fmt::Display for $name {
            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
                write!(f, "{}({})", stringify!($name), self.to_string())
            }
        }

        impl std::fmt::Debug for $name {
            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
                write!(f, "{}", self)
            }
        }


        impl serde::Serialize for $name {
            fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
                where S: serde::Serializer
            {
                serializer.serialize_str(&self.to_string())
            }
        }


        impl<'de> serde::Deserialize<'de> for $name {
            fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
                where D: serde::Deserializer<'de>
            {
                deserializer.deserialize_str($crate::CheckableVisitor{_type:std::marker::PhantomData})
            }
        }

    }
}


pub struct CheckableVisitor<T: Checkable> {
    pub _type: std::marker::PhantomData<T>,
}

impl<'de, Checked: Checkable> Visitor<'de> for CheckableVisitor<Checked> {
    type Value = Checked;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        formatter.write_str("An $name in String format!")
    }

    fn visit_str<E>(self, value: &str) -> result::Result<Checked, E>
        where E: de::Error
    {
        Checked::check(value).map_err(|e| {
                                          E::custom(format!("Failed to deserialize {} '{:?}'",
                                                            Checked::NAME,
                                                            e))
                                      })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde::{Serialize, Serializer, Deserialize, Deserializer};

    byte_seq!(Test; 10);

    #[test]
    fn serialize_deserialize() {
        let a = Test::generate_new();
        assert_eq!(a, Test::check(&a.to_string()).unwrap());
    }

    byte_seq!(ApiKey; 32);

    #[test]
    fn example() {
        // Creates a new ApiKey containing 32 random bytes using a thread_rng
        let key = ApiKey::generate_new();

        // The to_string method creates a hex encoded string:
        // i.e. 'BBC47F308F3D02C3C6C3D6C9555296A64407FE72AD92DE8C7344D610CFFABF67'
        assert_eq!(key.to_string().len(), 64);

        // you can also do it the other way around: Parse a string into an ApiKey
        let key = ApiKey::check("BBC47F308F3D02C3C6C3D6C9555296A64407FE72AD92DE8C7344D610CFFABF67").unwrap();
        assert_eq!(key.to_string(), "BBC47F308F3D02C3C6C3D6C9555296A64407FE72AD92DE8C7344D610CFFABF67");
    }

}