Refactor and add more documentation for the `Network` type.

Signed-off-by: Jean Pierre Dudey <jeandudey@hotmail.com>

src/network/constants.rs

@@ -12,28 +12,34 @@
 // If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
 //
 
-//! # Network constants
+//! Network constants
 //!
 //! This module provides various constants relating to the Bitcoin network
 //! protocol, such as protocol versioning and magic header bytes.
 //!
+//! The [`Network`][1] type implements the [`ConsensusDecodable`][2] and
+//! [`ConsensusEncodable`][3] and encodes the magic bytes of the given
+//! network
+//!
+//! [1]: enum.Network.html
+//! [2]: ../encodable/trait.ConsensusDecodable.html
+//! [3]: ../encodable/trait.ConsensusEncodable.html
+//!
+//! # Example: encoding a network's magic bytes
+//!
+//! ```rust
+//! use bitcoin::network::constants::Network;
+//! use bitcoin::network::serialize::serialize;
+//!
+//! let network = Network::Bitcoin;
+//! let bytes = serialize(&network).unwrap();
+//!
+//! assert_eq!(&bytes[..], &[0xF9, 0xBE, 0xB4, 0xD9]);
+//! ```
 
 use network::encodable::{ConsensusDecodable, ConsensusEncodable};
 use network::serialize::{SimpleEncoder, SimpleDecoder};
 
-user_enum! {
-    #[derive(Copy, PartialEq, Eq, Clone, Hash)]
-    #[doc="The cryptocurrency to act on"]
-    pub enum Network {
-        #[doc="Classic Bitcoin"]
-        Bitcoin <-> "bitcoin",
-        #[doc="Bitcoin's testnet"]
-        Testnet <-> "testnet",
-        #[doc="Bitcoin's regtest"]
-        Regtest <-> "regtest"
-    }
-}
-
 /// Version of the protocol as appearing in network message headers
 pub const PROTOCOL_VERSION: u32 = 70001;
 /// Bitfield of services provided by this node
@@ -41,34 +47,78 @@ pub const SERVICES: u64            = 0;
 /// User agent as it appears in the version message
 pub const USER_AGENT: &'static str = "bitcoin-rust v0.1";
 
-/// Return the network magic bytes, which should be encoded little-endian
+user_enum! {
-/// at the start of every message
+    /// The cryptocurrency to act on
-pub fn magic(network: Network) -> u32 {
+    #[derive(Copy, PartialEq, Eq, Clone, Hash)]
-    match network {
+    pub enum Network {
+        /// Classic Bitcoin
+        Bitcoin <-> "bitcoin",
+        /// Bitcoin's testnet
+        Testnet <-> "testnet",
+        /// Bitcoin's regtest
+        Regtest <-> "regtest"
+    }
+}
+
+impl Network {
+    /// Creates a `Network` from the magic bytes.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use bitcoin::network::constants::Network;
+    ///
+    /// assert_eq!(Some(Network::Bitcoin), Network::from_magic(0xD9B4BEF9));
+    /// assert_eq!(None, Network::from_magic(0xFFFFFFFF));
+    /// ```
+    pub fn from_magic(magic: u32) -> Option<Network> {
+        // Note: any new entries here must be added to `magic` below
+        match magic {
+            0xD9B4BEF9 => Some(Network::Bitcoin),
+            0x0709110B => Some(Network::Testnet),
+            0xDAB5BFFA => Some(Network::Regtest),
+            _ => None
+        }
+    }
+
+    /// Return the network magic bytes, which should be encoded little-endian
+    /// at the start of every message
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use bitcoin::network::constants::Network;
+    ///
+    /// let network = Network::Bitcoin;
+    /// assert_eq!(network.magic(), 0xD9B4BEF9);
+    /// ```
+    pub fn magic(&self) -> u32 {
+        // Note: any new entries here must be added to `from_magic` above
+        match *self {
             Network::Bitcoin => 0xD9B4BEF9,
             Network::Testnet => 0x0709110B,
             Network::Regtest => 0xDAB5BFFA,
-        // Note: any new entries here must be added to `consensus_decode` below
+        }
     }
 }
 
 impl<S: SimpleEncoder> ConsensusEncodable<S> for Network {
+    /// Encodes the magic bytes of `Network`.
     #[inline]
     fn consensus_encode(&self, s: &mut S) -> Result<(), S::Error> {
-        magic(*self).consensus_encode(s)
+        self.magic().consensus_encode(s)
     }
 }
 
 impl<D: SimpleDecoder> ConsensusDecodable<D> for Network {
+    /// Decodes the magic bytes of `Network`.
     #[inline]
     fn consensus_decode(d: &mut D) -> Result<Network, D::Error> {
-        let magic: u32 = try!(ConsensusDecodable::consensus_decode(d));
+        u32::consensus_decode(d)
-        match magic {
+            .and_then(|m| {
-            0xD9B4BEF9 => Ok(Network::Bitcoin),
+                Network::from_magic(m)
-            0x0709110B => Ok(Network::Testnet),
+                    .ok_or(d.error(format!("Unknown network (magic {:x})", m)))
-            0xDAB5BFFA => Ok(Network::Regtest),
+            })
-            x => Err(d.error(format!("Unknown network (magic {:x})", x)))
-        }
     }
 }
 

src/network/socket.rs

@@ -90,7 +90,7 @@ impl Socket {
             services: 0,
             version_nonce: rng.gen(),
             user_agent: constants::USER_AGENT.to_owned(),
-            magic: constants::magic(network)
+            magic: network.magic(),
         }
     }