⭐ new (ptth_relay): add serde deserializer for blake3 hashes

crates/ptth_relay/src/config.rs

@@ -4,18 +4,68 @@
 use std::{
 	collections::HashMap,
 	convert::{TryFrom, TryInto},
+	fmt,
 	iter::FromIterator,
+	ops::Deref,
 	path::Path,
 };
 
+use serde::{
+	Deserialize,
+	Deserializer,
+	de::{
+		self,
+		Visitor,
+	},
+};
+
 use crate::errors::ConfigError;
 
+pub struct BlakeHashWrapper (blake3::Hash);
+
+impl Deref for BlakeHashWrapper {
+	type Target = blake3::Hash;
+	
+	fn deref (&self) -> &<Self as Deref>::Target {
+		&self.0
+	}
+}
+
+struct BlakeHashVisitor;
+
+impl <'de> Visitor <'de> for BlakeHashVisitor {
+	type Value = blake3::Hash;
+	
+	fn expecting (&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+		formatter.write_str ("a 32-byte blake3 hash, encoded as base64")
+	}
+	
+	fn visit_str <E: de::Error> (self, value: &str) 
+	-> Result <Self::Value, E>
+	{
+		let bytes: Vec <u8> = base64::decode (value).map_err (|_| E::custom (format! ("str is not base64: {}", value)))?;
+		let bytes: [u8; 32] = (&bytes [..]).try_into ().map_err (|_| E::custom (format! ("decode base64 is not 32 bytes long: {}", value)))?;
+		
+		let tripcode = blake3::Hash::from (bytes);
+		
+		Ok (tripcode)
+	}
+}
+
+impl <'de> Deserialize <'de> for BlakeHashWrapper {
+	fn deserialize <D: Deserializer <'de>> (deserializer: D) -> Result <Self, D::Error> {
+		Ok (BlakeHashWrapper (deserializer.deserialize_str (BlakeHashVisitor)?))
+	}
+}
+
 // Stuff we need to load from the config file and use to
 // set up the HTTP server
 
 pub mod file {
 	use serde::Deserialize;
 	
+	use super::*;
+	
 	#[derive (Deserialize)]
 	pub struct Server {
 		pub name: String,
@@ -31,6 +81,8 @@ pub mod file {
 		pub enable_dev_mode:     bool,
 		#[serde (default)]
 		pub enable_scraper_auth: bool,
+		
+		pub dev_scraper_key: Option <BlakeHashWrapper>,
 	}
 	
 	#[derive (Deserialize)]