Replace PeerServices(u64) with a bitflags struct.

This gives considerably better ergonomics.

zebra-network/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+bitflags = "1.2"
 bytes = "0.4"
 rand = "0.7"
 byteorder = "1.3"

zebra-network/src/lib.rs

@@ -6,6 +6,8 @@
 extern crate failure;
 #[macro_use]
 extern crate tracing;
+#[macro_use]
+extern crate bitflags;
 
 mod network;
 pub use network::Network;

zebra-network/src/meta_addr.rs

@@ -31,7 +31,7 @@ pub struct MetaAddr {
 impl ZcashSerialize for MetaAddr {
     fn zcash_serialize<W: Write>(&self, mut writer: W) -> Result<(), SerializationError> {
         writer.write_u32::<LittleEndian>(self.last_seen.timestamp() as u32)?;
-        writer.write_u64::<LittleEndian>(self.services.0)?;
+        writer.write_u64::<LittleEndian>(self.services.bits())?;
         writer.write_socket_addr(self.addr)?;
         Ok(())
     }
@@ -41,7 +41,8 @@ impl ZcashDeserialize for MetaAddr {
     fn zcash_deserialize<R: Read>(mut reader: R) -> Result<Self, SerializationError> {
         Ok(MetaAddr {
             last_seen: Utc.timestamp(reader.read_u32::<LittleEndian>()? as i64, 0),
-            services: PeerServices(reader.read_u64::<LittleEndian>()?),
+            // Discard unknown service bits.
+            services: PeerServices::from_bits_truncate(reader.read_u64::<LittleEndian>()?),
             addr: reader.read_socket_addr()?,
         })
     }

zebra-network/src/protocol/codec.rs

@@ -174,15 +174,15 @@ impl Codec {
                 ref relay,
             } => {
                 writer.write_u32::<LittleEndian>(version.0)?;
-                writer.write_u64::<LittleEndian>(services.0)?;
+                writer.write_u64::<LittleEndian>(services.bits())?;
                 writer.write_i64::<LittleEndian>(timestamp.timestamp())?;
 
                 let (recv_services, recv_addr) = address_recv;
-                writer.write_u64::<LittleEndian>(recv_services.0)?;
+                writer.write_u64::<LittleEndian>(recv_services.bits())?;
                 writer.write_socket_addr(*recv_addr)?;
 
                 let (from_services, from_addr) = address_from;
-                writer.write_u64::<LittleEndian>(from_services.0)?;
+                writer.write_u64::<LittleEndian>(from_services.bits())?;
                 writer.write_socket_addr(*from_addr)?;
 
                 writer.write_u64::<LittleEndian>(nonce.0)?;
@@ -341,14 +341,15 @@ impl Codec {
     fn read_version<R: Read>(&self, mut reader: R) -> Result<Message, Error> {
         Ok(Message::Version {
             version: Version(reader.read_u32::<LittleEndian>()?),
-            services: PeerServices(reader.read_u64::<LittleEndian>()?),
+            // Use from_bits_truncate to discard unknown service bits.
+            services: PeerServices::from_bits_truncate(reader.read_u64::<LittleEndian>()?),
             timestamp: Utc.timestamp(reader.read_i64::<LittleEndian>()?, 0),
             address_recv: (
-                PeerServices(reader.read_u64::<LittleEndian>()?),
+                PeerServices::from_bits_truncate(reader.read_u64::<LittleEndian>()?),
                 reader.read_socket_addr()?,
             ),
             address_from: (
-                PeerServices(reader.read_u64::<LittleEndian>()?),
+                PeerServices::from_bits_truncate(reader.read_u64::<LittleEndian>()?),
                 reader.read_socket_addr()?,
             ),
             nonce: Nonce(reader.read_u64::<LittleEndian>()?),
@@ -505,7 +506,7 @@ mod tests {
     #[test]
     fn version_message_round_trip() {
         use std::net::{IpAddr, Ipv4Addr, SocketAddr};
-        let services = PeerServices(0x1);
+        let services = PeerServices::NODE_NETWORK;
         let timestamp = Utc.timestamp(1568000000, 0);
 
         let rt = Runtime::new().unwrap();

zebra-network/src/protocol/types.rs

@@ -8,11 +8,21 @@ pub struct Magic(pub [u8; 4]);
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub struct Version(pub u32);
 
-/// Bitfield of features to be enabled for this connection.
-// Tower provides utilities for service discovery, so this might go
-// away in the future in favor of that.
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-pub struct PeerServices(pub u64);
+bitflags! {
+    /// A bitflag describing services advertised by a node in the network.
+    ///
+    /// Note that bits 24-31 are reserved for temporary experiments; other
+    /// service bits should be allocated via the ZIP process.
+    #[derive(Default)]
+    pub struct PeerServices: u64 {
+        /// NODE_NETWORK means that the node is a full node capable of serving
+        /// blocks, as opposed to a light client that makes network requests but
+        /// does not provide network services.
+        const NODE_NETWORK = (1 << 0);
+        /// NODE_BLOOM means that the node supports bloom-filtered connections.
+        const NODE_BLOOM = (1 << 2);
+    }
+}
 
 /// A nonce used in the networking layer to identify messages.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]

zebrad/src/commands/connect.rs

@@ -70,13 +70,16 @@ impl ConnectCmd {
 
         let version = Message::Version {
             version: constants::CURRENT_VERSION,
-            services: PeerServices(1),
+            services: PeerServices::NODE_NETWORK,
             timestamp: Utc::now(),
-            address_recv: (PeerServices(1), self.addr),
+            address_recv: (PeerServices::NODE_NETWORK, self.addr),
             // We just make something up because at this stage the `connect` command
             // doesn't run a server or anything -- will the zcashd respond on the
             // same tcp connection or try to open one to the bogus address below?
-            address_from: (PeerServices(1), "127.0.0.1:9000".parse().unwrap()),
+            address_from: (
+                PeerServices::NODE_NETWORK,
+                "127.0.0.1:9000".parse().unwrap(),
+            ),
             nonce: Nonce(1),
             user_agent: "Zebra Connect".to_owned(),
             start_height: BlockHeight(0),