Merge pull request #33 from tox-rs/dht_bootstrap_info

feat(dht): add BootstrapInfo packet parsing

Author: kpp

src/toxcore/dht_new/packet.rs

@@ -25,7 +25,7 @@
     * takes care of the serializing and de-serializing DHT packets
 */
 
-use nom::{le_u8, be_u64, rest};
+use nom::{le_u8, be_u32, be_u64, rest};
 
 use std::io::{Error, ErrorKind};
 
@@ -78,7 +78,8 @@ pub enum DhtPacket {
     OnionResponse2(OnionResponse2),
     /// [`OnionResponse1`](../onion/struct.OnionResponse1.html) structure.
     OnionResponse1(OnionResponse1),
-    // TODO: BootstrapInfo
+    /// [`BootstrapInfo`](./struct.BootstrapInfo.html) structure.
+    BootstrapInfo(BootstrapInfo)
 }
 
 impl ToBytes for DhtPacket {
@@ -100,6 +101,7 @@ impl ToBytes for DhtPacket {
             DhtPacket::OnionResponse3(ref p) => p.to_bytes(buf),
             DhtPacket::OnionResponse2(ref p) => p.to_bytes(buf),
             DhtPacket::OnionResponse1(ref p) => p.to_bytes(buf),
+            DhtPacket::BootstrapInfo(ref p) => p.to_bytes(buf)
         }
     }
 }
@@ -121,7 +123,8 @@ impl FromBytes for DhtPacket {
         map!(OnionDataResponse::from_bytes, DhtPacket::OnionDataResponse) |
         map!(OnionResponse3::from_bytes, DhtPacket::OnionResponse3) |
         map!(OnionResponse2::from_bytes, DhtPacket::OnionResponse2) |
-        map!(OnionResponse1::from_bytes, DhtPacket::OnionResponse1)
+        map!(OnionResponse1::from_bytes, DhtPacket::OnionResponse1) |
+        map!(BootstrapInfo::from_bytes, DhtPacket::BootstrapInfo)
     ));
 }
 
@@ -804,6 +807,62 @@ impl FromBytes for LanDiscovery {
     ));
 }
 
+/** Sent by both client and server, only server will respond.
+When server receives this packet it may respond with the version of the library
+plus MoTD (message of the day). The max length of MoTD is 256 bytes so the max packet
+lenght of server BootstrapInfo is 261=(1+4+256) bytes.
+
+Client must send a BootstrapInfo of exactly 78 bytes, the only 1 field is required: `packet type`
+which is filled automatically. So version may be filled with any value, so does MoTD, but
+it has to be exactly 73=(78-1-4) bytes long. The server should check that the size of the
+packet is exactly 78 bytes long (or MoTD=73 bytes filled with any values). Frankly speaking,
+there should be neither `version` nor `motd` fields in the request version, the serialized form
+should be 1 byte with packet type + (78-1) bytes of trash, but this implementation is simplified.
+
+Serialized form:
+
+Length      | Contents
+----------- | --------
+`1`         | `0xF0`
+`4`         | Version in BigEndian
+variable    | MoTD, must not longer than 256 bytes
+
+*/
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct BootstrapInfo {
+    /// The version of DHT server
+    pub version: u32,
+    /// Message of the day
+    pub motd: Vec<u8>,
+}
+
+/// Length of in bytes of MoTD field of [`BootstrapInfo`](./struct.BootstrapInfo.html)
+/// when server responds with info.
+pub const BOOSTRAP_SERVER_MAX_MOTD_LENGTH: usize = 256;
+/// Length of in bytes of MoTD field of [`BootstrapInfo`](./struct.BootstrapInfo.html)
+/// when client requests info. 73 = 78 (max client request len) - 1 (type) - 4 (version)
+pub const BOOSTRAP_CLIENT_MAX_MOTD_LENGTH: usize = 73;
+
+impl ToBytes for BootstrapInfo {
+    fn to_bytes<'a>(&self, buf: (&'a mut [u8], usize)) -> Result<(&'a mut [u8], usize), GenError> {
+        do_gen!(buf,
+            gen_be_u8!(0xf0) >>
+            gen_be_u32!(self.version) >>
+            gen_slice!(self.motd.as_slice())
+        )
+    }
+}
+
+impl FromBytes for BootstrapInfo {
+    named!(from_bytes<BootstrapInfo>, do_parse!(
+        tag!(&[0xf0][..]) >>
+        version: be_u32 >>
+        motd: verify!(rest, |motd: &[u8]| motd.len() <= BOOSTRAP_SERVER_MAX_MOTD_LENGTH) >>
+        (BootstrapInfo { version, motd: motd.to_vec() })
+    ));
+}
+
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1295,6 +1354,14 @@ mod tests {
         })
     );
 
+    encode_decode_test!(
+        bootstrap_info_encode_decode,
+        DhtPacket::BootstrapInfo(BootstrapInfo {
+            version: 42,
+            motd: vec![1, 2, 3, 4]
+        })
+    );
+
     macro_rules! dht_packet_encrypt_decrypt (
         ($test:ident, $packet:ident, $payload:expr) => (
             #[test]