Derive std::error::Error for error types

Cargo.toml

@@ -2,7 +2,7 @@
 name = "nettext"
 description = "A text-based data format for cryptographic network protocols"
 authors = ["Alex Auvolat <alex@adnab.me>"]
-version = "0.2.2"
+version = "0.2.3"
 edition = "2021"
 license = "AGPL-3.0"
 readme = "README.md"
@@ -12,6 +12,7 @@ readme = "README.md"
 [dependencies]
 nom = "7.1"
 base64 = "0.13"
+err-derive = "0.3"
 
 dryoc = { version = "0.4", optional = true }
 serde = { version = "1.0", optional = true, features = ["derive"] }

src/crypto/mod.rs

@@ -20,7 +20,6 @@ impl enc::Encode for sign::SigningKeyPair<sign::PublicKey, sign::SecretKey> {
     }
 }
 
-
 // ---- helpers ----
 
 /// Compute the hash of a payload with default dryoc parameters and optionnal key
@@ -30,10 +29,20 @@ pub fn compute_hash(bytes: &[u8], key: Option<&[u8; 32]>) -> generichash::Hash {
 
 /// Compute the ed25519 signature of a message using a secret key
 pub fn compute_signature(message: &[u8], secret_key: &sign::SecretKey) -> sign::Signature {
-	SigningKeyPair::from_secret_key(secret_key.clone()).sign_with_defaults(message).unwrap().into_parts().0
+    SigningKeyPair::from_secret_key(secret_key.clone())
+        .sign_with_defaults(message)
+        .unwrap()
+        .into_parts()
+        .0
 }
 
 /// Verify the ed25519 signature of a message using a public key
-pub fn verify_signature(signature: &sign::Signature, message: &[u8], public_key: &sign::PublicKey) -> bool {
-	sign::SignedMessage::from_parts(signature.clone(), message).verify(public_key).is_ok()
+pub fn verify_signature(
+    signature: &sign::Signature,
+    message: &[u8],
+    public_key: &sign::PublicKey,
+) -> bool {
+    sign::SignedMessage::from_parts(signature.clone(), message)
+        .verify(public_key)
+        .is_ok()
 }

src/dec/error.rs

@@ -1,19 +1,26 @@
-use std::fmt;
+use err_derive::Error;
 
 use crate::dec::debug;
 
 /// The type of errors returned by helper functions on `Term`
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Error)]
 pub enum TypeError {
     /// The term could not be decoded in the given type
+    #[error(display = "Not a {}", _0)]
     WrongType(&'static str),
+
     /// The term is not an array of the requested length
+    #[error(display = "Expected {} items, got {}", _0, _1)]
     WrongLength(usize, usize),
+
     /// The dictionnary is missing a key
+    #[error(display = "Missing key `{}` in dict", _0)]
     MissingKey(String),
     /// The dictionnary contains an invalid key
+    #[error(display = "Spurrious/unexpected key `{}` in dict", _0)]
     UnexpectedKey(String),
     /// The underlying raw string contains garbage (should not happen in theory)
+    #[error(display = "Garbage in underlying data")]
     Garbage,
 }
 
@@ -23,18 +30,6 @@ impl From<std::str::Utf8Error> for TypeError {
     }
 }
 
-impl std::fmt::Display for TypeError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            TypeError::WrongType(t) => write!(f, "Not a {}", t),
-            TypeError::WrongLength(n, m) => write!(f, "Expected {} items, got {}", m, n),
-            TypeError::MissingKey(k) => write!(f, "Missing key `{}` in dict", k),
-            TypeError::UnexpectedKey(k) => write!(f, "Spurrious/unexpected key `{}` in dict", k),
-            TypeError::Garbage => write!(f, "Garbage in underlying data"),
-        }
-    }
-}
-
 // ----
 
 /// The error kind returned by the `decode` function.
@@ -64,6 +59,8 @@ impl<'a> std::fmt::Debug for DecodeError<'a> {
     }
 }
 
+impl<'a> std::error::Error for DecodeError<'a> {}
+
 impl<'a> From<nom::Err<nom::error::Error<&'a [u8]>>> for DecodeError<'a> {
     fn from(e: nom::Err<nom::error::Error<&'a [u8]>>) -> DecodeError<'a> {
         match e {

src/enc/error.rs

@@ -1,23 +1,18 @@
-use std::fmt;
+use err_derive::Error;
 
 /// An error that happenned when creating a nettext encoder term
-#[derive(Debug)]
+#[derive(Debug, Error)]
 pub enum Error {
+    #[error(display = "Invalid character '{}'", _0)]
     InvalidCharacter(u8),
+    #[error(display = "Invalid RAW nettext litteral")]
     InvalidRaw,
+    #[error(display = "Tried to insert into a term that isn't a dictionnary")]
     NotADictionnary,
+    #[error(display = "Duplicate key: {}", _0)]
     DuplicateKey(String),
+    #[error(
+        display = "Refusing to build nested lists with list(), use either list_flatten() or list_nested()"
+    )]
     ListInList,
 }
-
-impl std::fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Error::InvalidCharacter(c) => write!(f, "Invalid character '{}'", *c as char),
-            Error::InvalidRaw => write!(f, "Invalid RAW nettext litteral"),
-            Error::NotADictionnary => write!(f, "Tried to insert into a term that isn't a dictionnary"),
-            Error::DuplicateKey(s) => write!(f, "Duplicate dict key: {}", s),
-            Error::ListInList => write!(f, "Refusing to build nested lists with list(), use either list_flatten() or list_nested()"),
-        }
-    }
-}