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
// Bitcoin Hashes Library
// Written in 2018 by
//   Andrew Poelstra <apoelstra@wpsoftware.net>
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! Macros for serde trait impls, and supporting code

#[cfg(feature = "serde")]
/// Functions used by serde impls of all hashes
pub mod serde_details {
    use Error;

    use core::marker::PhantomData;
    use core::{fmt, ops};
    struct HexVisitor<ValueT>(PhantomData<ValueT>);
    use serde::{de, Serializer, Deserializer};
    use hex::{FromHex, ToHex};

    impl<'de, ValueT> de::Visitor<'de> for HexVisitor<ValueT>
    where
        ValueT: FromHex,
    {
        type Value = ValueT;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("an ASCII hex string")
        }

        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            if let Ok(hex) = ::std::str::from_utf8(v) {
                Self::Value::from_hex(hex).map_err(E::custom)
            } else {
                return Err(E::invalid_value(
                    de::Unexpected::Bytes(v),
                    &self,
                ));
            }
        }

        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            Self::Value::from_hex(v).map_err(E::custom)
        }
    }

    struct BytesVisitor<ValueT>(PhantomData<ValueT>);

    impl<'de, ValueT> de::Visitor<'de> for BytesVisitor<ValueT>
    where ValueT : SerdeHash {
        type Value = ValueT;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("a bytestring")
        }

        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            SerdeHash::from_slice_delegated(v).map_err(|_| {
                // from_slice only errors on incorrect length
                E::invalid_length(v.len(), &stringify!(N))
            })
        }
    }

    /// Default serialization/deserialization methods
    pub trait SerdeHash
    where
        Self: Sized
            + ToHex
            + FromHex
            + ops::Index<usize, Output = u8>
            + ops::Index<ops::RangeFull, Output = [u8]>
    {
        /// Size, in bits, of the hash
        const N: usize;

        /// helper function to turn a deserialized slice into the correct hash type
        fn from_slice_delegated(sl: &[u8]) -> Result<Self, Error>;

        /// serde serialization
        fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
            if s.is_human_readable() {
                s.serialize_str(&self.to_hex())
            } else {
                s.serialize_bytes(&self[..])
            }
        }

        /// serde deserialization
        fn deserialize<'de, D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
            if d.is_human_readable() {
                d.deserialize_str(HexVisitor::<Self>(PhantomData))
            } else {
                d.deserialize_bytes(BytesVisitor::<Self>(PhantomData))
            }
        }
    }
}

#[macro_export]
#[cfg(feature = "serde")]
/// Implements `Serialize` and `Deserialize` for a type `$t` which
/// represents a newtype over a byte-slice over length `$len`
macro_rules! serde_impl(
    ($t:ident, $len:expr) => (
        impl $crate::serde_macros::serde_details::SerdeHash for $t {
            const N : usize = $len;
            fn from_slice_delegated(sl: &[u8]) -> Result<Self, $crate::Error> {
                $t::from_slice(sl)
            }
        }

        impl $crate::serde::Serialize for $t {
            fn serialize<S: $crate::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
                $crate::serde_macros::serde_details::SerdeHash::serialize(self, s)
            }
        }

        impl<'de> $crate::serde::Deserialize<'de> for $t {
            fn deserialize<D: $crate::serde::Deserializer<'de>>(d: D) -> Result<$t, D::Error> {
                $crate::serde_macros::serde_details::SerdeHash::deserialize(d)
            }
        }
));

/// Does an "empty" serde implementation for the configuration without serde feature
#[macro_export]
#[cfg(not(feature = "serde"))]
macro_rules! serde_impl(
        ($t:ident, $len:expr) => ()
);