Add a Magic type for network magics.

zebra-network/src/constants.rs

@@ -2,5 +2,14 @@
 
 use crate::types::*;
 
-/// The Zcash version used on mainnet.
-pub const ZCASH_VERSION: Version = Version(170_007);
+/// The Zcash network protocol version used on mainnet.
+pub const CURRENT_VERSION: Version = Version(170_007);
+
+/// Magic numbers used to identify different Zcash networks.
+pub mod magics {
+    use super::*;
+    /// The production mainnet.
+    pub const MAINNET: Magic = Magic(0x6427e924);
+    /// The testnet.
+    pub const TESTNET: Magic = Magic(0xbff91afa);
+}

zebra-network/src/types.rs

@@ -1,8 +1,9 @@
 //! Newtype wrappers assigning semantic meaning to primitive types.
 
-use std::net::SocketAddr;
+/// A magic number identifying the network.
+pub struct Magic(pub u32);
 
-/// A protocol version magic number.
+/// A protocol version number.
 pub struct Version(pub u32);
 
 /// Bitfield of features to be enabled for this connection.