From 0a85be285dac1c4083dab3ccb1a2ac5f561dfd81 Mon Sep 17 00:00:00 2001
From: Henry de Valence <hdevalence@hdevalence.ca>
Date: Wed, 25 Sep 2019 16:20:02 -0700
Subject: [PATCH] Add addr, getaddr serialization.

---
 zebra-network/src/meta_addr.rs      | 28 ++++++++++++++++++++++-
 zebra-network/src/protocol/codec.rs | 35 ++++++++++++++++++++++++++---
 2 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/zebra-network/src/meta_addr.rs b/zebra-network/src/meta_addr.rs
index 8af5fb387..6f014dbea 100644
--- a/zebra-network/src/meta_addr.rs
+++ b/zebra-network/src/meta_addr.rs
@@ -1,8 +1,15 @@
 //! An address-with-metadata type used in Bitcoin networking.
 
-use chrono::{DateTime, Utc};
+use std::io::{Read, Write};
 use std::net::SocketAddr;
 
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use chrono::{DateTime, TimeZone, Utc};
+
+use zebra_chain::serialization::{
+    ReadZcashExt, SerializationError, WriteZcashExt, ZcashDeserialize, ZcashSerialize,
+};
+
 use crate::protocol::types::Services;
 
 /// An address with metadata on its advertised services and last-seen time.
@@ -20,3 +27,22 @@ pub struct MetaAddr {
     /// When the peer was last seen.
     pub last_seen: DateTime<Utc>,
 }
+
+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_socket_addr(self.addr)?;
+        Ok(())
+    }
+}
+
+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: Services(reader.read_u64::<LittleEndian>()?),
+            addr: reader.read_socket_addr()?,
+        })
+    }
+}
diff --git a/zebra-network/src/protocol/codec.rs b/zebra-network/src/protocol/codec.rs
index a1ffeed6e..330d38346 100644
--- a/zebra-network/src/protocol/codec.rs
+++ b/zebra-network/src/protocol/codec.rs
@@ -197,6 +197,13 @@ impl Codec {
             Pong(nonce) => {
                 writer.write_u64::<LittleEndian>(nonce.0)?;
             }
+            GetAddr => { /* Empty payload -- no-op */ }
+            Addr(ref addrs) => {
+                writer.write_compactsize(addrs.len() as u64)?;
+                for addr in addrs {
+                    addr.zcash_serialize(&mut writer)?;
+                }
+            }
             Inv(ref hashes) => {
                 writer.write_compactsize(hashes.len() as u64)?;
                 for hash in hashes {
@@ -372,9 +379,31 @@ impl Codec {
         bail!("unimplemented message type")
     }
 
-    fn read_addr<R: Read>(&self, mut _reader: R) -> Result<Message, Error> {
-        trace!("addr");
-        bail!("unimplemented message type")
+    fn read_addr<R: Read>(&self, mut reader: R) -> Result<Message, Error> {
+        use crate::meta_addr::MetaAddr;
+
+        // XXX we may want to factor this logic out into
+        // fn read_vec<R: Read, T: ZcashDeserialize>(reader: R) -> Result<Vec<T>, Error>
+        // on ReadZcashExt (and similarly for WriteZcashExt)
+        let count = reader.read_compactsize()? as usize;
+        // Preallocate a buffer, performing a single allocation in the honest
+        // case. Although the size of the recieved data buffer is bounded by the
+        // codec's max_len field, it's still possible for someone to send a
+        // short addr message with a large count field, so if we naively trust
+        // the count field we could be tricked into preallocating a large
+        // buffer. Instead, calculate the maximum count for a valid message from
+        // the codec's max_len using ENCODED_ADDR_SIZE.
+        //
+        // addrs are encoded as: timestamp + services + ipv6 + port
+        const ENCODED_ADDR_SIZE: usize = 4 + 8 + 16 + 2;
+        let max_count = self.builder.max_len / ENCODED_ADDR_SIZE;
+        let mut addrs = Vec::with_capacity(std::cmp::min(count, max_count));
+
+        for _ in 0..count {
+            addrs.push(MetaAddr::zcash_deserialize(&mut reader)?);
+        }
+
+        Ok(Message::Addr(addrs))
     }
 
     fn read_getaddr<R: Read>(&self, mut _reader: R) -> Result<Message, Error> {