|
| 1 | +use { |
| 2 | + serde::{Deserialize, Serialize}, |
| 3 | + solana_short_vec as short_vec, |
| 4 | +}; |
| 5 | + |
| 6 | +/// Type-Length-Value encoding wrapper for bincode |
| 7 | +#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)] |
| 8 | +pub(crate) struct TlvRecord { |
| 9 | + // type |
| 10 | + pub(crate) typ: u8, |
| 11 | + // length and serialized bytes of the value |
| 12 | + #[serde(with = "short_vec")] |
| 13 | + pub(crate) bytes: Vec<u8>, |
| 14 | +} |
| 15 | + |
| 16 | +/// Macro that provides a quick and easy way to define TLV compatible enums |
| 17 | +#[macro_export] |
| 18 | +macro_rules! define_tlv_enum { |
| 19 | + ( |
| 20 | + $vis:vis enum $enum_name:ident { |
| 21 | + $($typ:literal => $variant:ident($inner:ty)),* $(,)? |
| 22 | + } |
| 23 | + ) => { |
| 24 | + // define the enum itself |
| 25 | + #[derive(Debug, Clone, Eq, PartialEq)] |
| 26 | + $vis enum $enum_name { |
| 27 | + $( |
| 28 | + $variant($inner), |
| 29 | + )* |
| 30 | + } |
| 31 | + |
| 32 | + // Serialize enum by first converting into TlvRecord, and then serializing that |
| 33 | + impl serde::Serialize for $enum_name { |
| 34 | + fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> |
| 35 | + where |
| 36 | + S: serde::Serializer, |
| 37 | + { |
| 38 | + let tlv_rec = TlvRecord::try_from(self).map_err(|e| serde::ser::Error::custom(e))?; |
| 39 | + tlv_rec.serialize(serializer) |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + // define conversion from TLV wire format |
| 44 | + impl TryFrom<&TlvRecord> for $enum_name { |
| 45 | + type Error = bincode::Error; |
| 46 | + fn try_from(value: &TlvRecord) -> Result<Self, Self::Error> { |
| 47 | + use serde::ser::Error; |
| 48 | + match value.typ { |
| 49 | + $( |
| 50 | + $typ => Ok(Self::$variant(bincode::deserialize::<$inner>(&value.bytes)?)), |
| 51 | + )* |
| 52 | + _ => Err(bincode::Error::custom("Invalid type")), |
| 53 | + } |
| 54 | + } |
| 55 | + } |
| 56 | + // define conversion into TLV wire format |
| 57 | + impl TryFrom<&$enum_name> for TlvRecord { |
| 58 | + type Error = bincode::Error; |
| 59 | + fn try_from(value: &$enum_name) -> Result<Self, Self::Error> { |
| 60 | + match value { |
| 61 | + $( |
| 62 | + $enum_name::$variant(inner) => Ok(TlvRecord { |
| 63 | + typ: $typ, |
| 64 | + bytes: bincode::serialize(inner)?, |
| 65 | + }), |
| 66 | + )* |
| 67 | + } |
| 68 | + } |
| 69 | + } |
| 70 | + }; |
| 71 | +} |
| 72 | + |
| 73 | +/// Parses a slice of serialized TLV records into a provided type. Unsupported |
| 74 | +/// TLV records are ignored. |
| 75 | +pub(crate) fn parse<'a, T: TryFrom<&'a TlvRecord>>(entries: &'a [TlvRecord]) -> Vec<T> { |
| 76 | + entries.iter().filter_map(|v| T::try_from(v).ok()).collect() |
| 77 | +} |
| 78 | + |
| 79 | +#[cfg(test)] |
| 80 | +mod tests { |
| 81 | + use crate::{define_tlv_enum, tlv::TlvRecord}; |
| 82 | + |
| 83 | + define_tlv_enum! (pub(crate) enum ExtensionNew { |
| 84 | + 1=>Test(u64), |
| 85 | + 2=>LegacyString(String), |
| 86 | + 3=>NewString(String), |
| 87 | + }); |
| 88 | + |
| 89 | + define_tlv_enum! ( pub(crate) enum ExtensionLegacy { |
| 90 | + 1=>Test(u64), |
| 91 | + 2=>LegacyString(String), |
| 92 | + }); |
| 93 | + |
| 94 | + /// Test that TLV encoded data is backwards-compatible, |
| 95 | + /// i.e. that new TLV data can be decoded by a new |
| 96 | + /// receiver where possible, and skipped otherwise |
| 97 | + #[test] |
| 98 | + fn test_tlv_backwards_compat() { |
| 99 | + let new_tlv_data = vec![ |
| 100 | + ExtensionNew::Test(42), |
| 101 | + ExtensionNew::NewString(String::from("bla")), |
| 102 | + ]; |
| 103 | + |
| 104 | + let new_bytes = bincode::serialize(&new_tlv_data).unwrap(); |
| 105 | + let tlv_vec: Vec<TlvRecord> = bincode::deserialize(&new_bytes).unwrap(); |
| 106 | + // check that both TLV are encoded correctly |
| 107 | + let new: Vec<ExtensionNew> = crate::tlv::parse(&tlv_vec); |
| 108 | + assert!(matches!(new[0], ExtensionNew::Test(42))); |
| 109 | + if let ExtensionNew::NewString(s) = &new[1] { |
| 110 | + assert_eq!(s, "bla"); |
| 111 | + } else { |
| 112 | + panic!("Wrong deserialization") |
| 113 | + }; |
| 114 | + // Make sure legacy recover works correctly |
| 115 | + let legacy: Vec<ExtensionLegacy> = crate::tlv::parse(&tlv_vec); |
| 116 | + assert!(matches!(legacy[0], ExtensionLegacy::Test(42))); |
| 117 | + assert_eq!(legacy.len(), 1, "Legacy parser should only recover ") |
| 118 | + } |
| 119 | + |
| 120 | + /// Test that TLV encoded data is forwards-compatible, |
| 121 | + /// i.e. that legacy TLV data can be decoded by a new |
| 122 | + /// receiver |
| 123 | + #[test] |
| 124 | + fn test_tlv_forward_compat() { |
| 125 | + let legacy_tlv_data = vec![ |
| 126 | + ExtensionLegacy::Test(42), |
| 127 | + ExtensionLegacy::LegacyString(String::from("foo")), |
| 128 | + ]; |
| 129 | + let legacy_bytes = bincode::serialize(&legacy_tlv_data).unwrap(); |
| 130 | + |
| 131 | + let tlv_vec: Vec<TlvRecord> = bincode::deserialize(&legacy_bytes).unwrap(); |
| 132 | + // Just in case make sure that legacy data is serialized correctly |
| 133 | + let legacy: Vec<ExtensionLegacy> = crate::tlv::parse(&tlv_vec); |
| 134 | + assert!(matches!(legacy[0], ExtensionLegacy::Test(42))); |
| 135 | + if let ExtensionLegacy::LegacyString(s) = &legacy[1] { |
| 136 | + assert_eq!(s, "foo"); |
| 137 | + } else { |
| 138 | + panic!("Wrong deserialization") |
| 139 | + }; |
| 140 | + // Parse the same bytes using new parser |
| 141 | + let new: Vec<ExtensionNew> = crate::tlv::parse(&tlv_vec); |
| 142 | + assert!(matches!(new[0], ExtensionNew::Test(42))); |
| 143 | + if let ExtensionNew::LegacyString(s) = &new[1] { |
| 144 | + assert_eq!(s, "foo"); |
| 145 | + } else { |
| 146 | + panic!("Wrong deserialization") |
| 147 | + }; |
| 148 | + } |
| 149 | +} |
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