Rename eth2_libp2p to lighthouse_network (#2702)

## Description

The `eth2_libp2p` crate was originally named and designed to incorporate a simple libp2p integration into lighthouse. Since its origins the crates purpose has expanded dramatically. It now houses a lot more sophistication that is specific to lighthouse and no longer just a libp2p integration. 

As of this writing it currently houses the following high-level lighthouse-specific logic:
- Lighthouse's implementation of the eth2 RPC protocol and specific encodings/decodings
- Integration and handling of ENRs with respect to libp2p and eth2
- Lighthouse's discovery logic, its integration with discv5 and logic about searching and handling peers. 
- Lighthouse's peer manager - This is a large module handling various aspects of Lighthouse's network, such as peer scoring, handling pings and metadata, connection maintenance and recording, etc.
- Lighthouse's peer database - This is a collection of information stored for each individual peer which is specific to lighthouse. We store connection state, sync state, last seen ips and scores etc. The data stored for each peer is designed for various elements of the lighthouse code base such as syncing and the http api.
- Gossipsub scoring - This stores a collection of gossipsub 1.1 scoring mechanisms that are continuously analyssed and updated based on the ethereum 2 networks and how Lighthouse performs on these networks.
- Lighthouse specific types for managing gossipsub topics, sync status and ENR fields
- Lighthouse's network HTTP API metrics - A collection of metrics for lighthouse network monitoring
- Lighthouse's custom configuration of all networking protocols, RPC, gossipsub, discovery, identify and libp2p. 

Therefore it makes sense to rename the crate to be more akin to its current purposes, simply that it manages the majority of Lighthouse's network stack. This PR renames this crate to `lighthouse_network`

Co-authored-by: Paul Hauner <paul@paulhauner.com>

beacon_node/lighthouse_network/src/rpc/codec/base.rs

@@ -0,0 +1,295 @@
+//! This handles the various supported encoding mechanism for the Eth 2.0 RPC.
+
+use crate::rpc::methods::ErrorType;
+use crate::rpc::{InboundRequest, OutboundRequest, RPCCodedResponse, RPCResponse};
+use libp2p::bytes::BufMut;
+use libp2p::bytes::BytesMut;
+use std::marker::PhantomData;
+use tokio_util::codec::{Decoder, Encoder};
+use types::EthSpec;
+
+pub trait OutboundCodec<TItem>: Encoder<TItem> + Decoder {
+    type CodecErrorType;
+
+    fn decode_error(
+        &mut self,
+        src: &mut BytesMut,
+    ) -> Result<Option<Self::CodecErrorType>, <Self as Decoder>::Error>;
+}
+
+/* Global Inbound Codec */
+// This deals with Decoding RPC Requests from other peers and encoding our responses
+
+pub struct BaseInboundCodec<TCodec, TSpec>
+where
+    TCodec: Encoder<RPCCodedResponse<TSpec>> + Decoder,
+    TSpec: EthSpec,
+{
+    /// Inner codec for handling various encodings
+    inner: TCodec,
+    phantom: PhantomData<TSpec>,
+}
+
+impl<TCodec, TSpec> BaseInboundCodec<TCodec, TSpec>
+where
+    TCodec: Encoder<RPCCodedResponse<TSpec>> + Decoder,
+    TSpec: EthSpec,
+{
+    pub fn new(codec: TCodec) -> Self {
+        BaseInboundCodec {
+            inner: codec,
+            phantom: PhantomData,
+        }
+    }
+}
+
+/* Global Outbound Codec */
+// This deals with Decoding RPC Responses from other peers and encoding our requests
+pub struct BaseOutboundCodec<TOutboundCodec, TSpec>
+where
+    TOutboundCodec: OutboundCodec<OutboundRequest<TSpec>>,
+    TSpec: EthSpec,
+{
+    /// Inner codec for handling various encodings.
+    inner: TOutboundCodec,
+    /// Keeps track of the current response code for a chunk.
+    current_response_code: Option<u8>,
+    phantom: PhantomData<TSpec>,
+}
+
+impl<TOutboundCodec, TSpec> BaseOutboundCodec<TOutboundCodec, TSpec>
+where
+    TSpec: EthSpec,
+    TOutboundCodec: OutboundCodec<OutboundRequest<TSpec>>,
+{
+    pub fn new(codec: TOutboundCodec) -> Self {
+        BaseOutboundCodec {
+            inner: codec,
+            current_response_code: None,
+            phantom: PhantomData,
+        }
+    }
+}
+
+/* Implementation of the Encoding/Decoding for the global codecs */
+
+/* Base Inbound Codec */
+
+// This Encodes RPC Responses sent to external peers
+impl<TCodec, TSpec> Encoder<RPCCodedResponse<TSpec>> for BaseInboundCodec<TCodec, TSpec>
+where
+    TSpec: EthSpec,
+    TCodec: Decoder + Encoder<RPCCodedResponse<TSpec>>,
+{
+    type Error = <TCodec as Encoder<RPCCodedResponse<TSpec>>>::Error;
+
+    fn encode(
+        &mut self,
+        item: RPCCodedResponse<TSpec>,
+        dst: &mut BytesMut,
+    ) -> Result<(), Self::Error> {
+        dst.clear();
+        dst.reserve(1);
+        dst.put_u8(
+            item.as_u8()
+                .expect("Should never encode a stream termination"),
+        );
+        self.inner.encode(item, dst)
+    }
+}
+
+// This Decodes RPC Requests from external peers
+impl<TCodec, TSpec> Decoder for BaseInboundCodec<TCodec, TSpec>
+where
+    TSpec: EthSpec,
+    TCodec: Encoder<RPCCodedResponse<TSpec>> + Decoder<Item = InboundRequest<TSpec>>,
+{
+    type Item = InboundRequest<TSpec>;
+    type Error = <TCodec as Decoder>::Error;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        self.inner.decode(src)
+    }
+}
+
+/* Base Outbound Codec */
+
+// This Encodes RPC Requests sent to external peers
+impl<TCodec, TSpec> Encoder<OutboundRequest<TSpec>> for BaseOutboundCodec<TCodec, TSpec>
+where
+    TSpec: EthSpec,
+    TCodec: OutboundCodec<OutboundRequest<TSpec>> + Encoder<OutboundRequest<TSpec>>,
+{
+    type Error = <TCodec as Encoder<OutboundRequest<TSpec>>>::Error;
+
+    fn encode(
+        &mut self,
+        item: OutboundRequest<TSpec>,
+        dst: &mut BytesMut,
+    ) -> Result<(), Self::Error> {
+        self.inner.encode(item, dst)
+    }
+}
+
+// This decodes RPC Responses received from external peers
+impl<TCodec, TSpec> Decoder for BaseOutboundCodec<TCodec, TSpec>
+where
+    TSpec: EthSpec,
+    TCodec: OutboundCodec<OutboundRequest<TSpec>, CodecErrorType = ErrorType>
+        + Decoder<Item = RPCResponse<TSpec>>,
+{
+    type Item = RPCCodedResponse<TSpec>;
+    type Error = <TCodec as Decoder>::Error;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        // if we have only received the response code, wait for more bytes
+        if src.len() <= 1 {
+            return Ok(None);
+        }
+        // using the response code determine which kind of payload needs to be decoded.
+        let response_code = self.current_response_code.unwrap_or_else(|| {
+            let resp_code = src.split_to(1)[0];
+            self.current_response_code = Some(resp_code);
+            resp_code
+        });
+
+        let inner_result = {
+            if RPCCodedResponse::<TSpec>::is_response(response_code) {
+                // decode an actual response and mutates the buffer if enough bytes have been read
+                // returning the result.
+                self.inner
+                    .decode(src)
+                    .map(|r| r.map(RPCCodedResponse::Success))
+            } else {
+                // decode an error
+                self.inner
+                    .decode_error(src)
+                    .map(|r| r.map(|resp| RPCCodedResponse::from_error(response_code, resp)))
+            }
+        };
+        // if the inner decoder was capable of decoding a chunk, we need to reset the current
+        // response code for the next chunk
+        if let Ok(Some(_)) = inner_result {
+            self.current_response_code = None;
+        }
+        // return the result
+        inner_result
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::ssz_snappy::*;
+    use super::*;
+    use crate::rpc::protocol::*;
+
+    use std::sync::Arc;
+    use types::{ForkContext, Hash256};
+    use unsigned_varint::codec::Uvi;
+
+    type Spec = types::MainnetEthSpec;
+
+    fn fork_context() -> ForkContext {
+        ForkContext::new::<Spec>(types::Slot::new(0), Hash256::zero(), &Spec::default_spec())
+    }
+
+    #[test]
+    fn test_decode_status_message() {
+        let message = hex::decode("0054ff060000734e615070590032000006e71e7b54989925efd6c9cbcb8ceb9b5f71216f5137282bf6a1e3b50f64e42d6c7fb347abe07eb0db8200000005029e2800").unwrap();
+        let mut buf = BytesMut::new();
+        buf.extend_from_slice(&message);
+
+        let snappy_protocol_id =
+            ProtocolId::new(Protocol::Status, Version::V1, Encoding::SSZSnappy);
+
+        let fork_context = Arc::new(fork_context());
+        let mut snappy_outbound_codec =
+            SSZSnappyOutboundCodec::<Spec>::new(snappy_protocol_id, 1_048_576, fork_context);
+
+        // remove response code
+        let mut snappy_buf = buf.clone();
+        let _ = snappy_buf.split_to(1);
+
+        // decode message just as snappy message
+        let _snappy_decoded_message = snappy_outbound_codec.decode(&mut snappy_buf).unwrap();
+
+        // build codecs for entire chunk
+        let mut snappy_base_outbound_codec = BaseOutboundCodec::new(snappy_outbound_codec);
+
+        // decode message as ssz snappy chunk
+        let _snappy_decoded_chunk = snappy_base_outbound_codec.decode(&mut buf).unwrap();
+    }
+
+    #[test]
+    fn test_invalid_length_prefix() {
+        let mut uvi_codec: Uvi<u128> = Uvi::default();
+        let mut dst = BytesMut::with_capacity(1024);
+
+        // Smallest > 10 byte varint
+        let len: u128 = 2u128.pow(70);
+
+        // Insert length-prefix
+        uvi_codec.encode(len, &mut dst).unwrap();
+
+        let snappy_protocol_id =
+            ProtocolId::new(Protocol::Status, Version::V1, Encoding::SSZSnappy);
+
+        let fork_context = Arc::new(fork_context());
+        let mut snappy_outbound_codec =
+            SSZSnappyOutboundCodec::<Spec>::new(snappy_protocol_id, 1_048_576, fork_context);
+
+        let snappy_decoded_message = snappy_outbound_codec.decode(&mut dst).unwrap_err();
+
+        assert_eq!(
+            snappy_decoded_message,
+            RPCError::IoError("input bytes exceed maximum".to_string()),
+            "length-prefix of > 10 bytes is invalid"
+        );
+    }
+
+    #[test]
+    fn test_length_limits() {
+        fn encode_len(len: usize) -> BytesMut {
+            let mut uvi_codec: Uvi<usize> = Uvi::default();
+            let mut dst = BytesMut::with_capacity(1024);
+            uvi_codec.encode(len, &mut dst).unwrap();
+            dst
+        }
+
+        let protocol_id =
+            ProtocolId::new(Protocol::BlocksByRange, Version::V1, Encoding::SSZSnappy);
+
+        // Response limits
+        let limit = protocol_id.rpc_response_limits::<Spec>();
+        let mut max = encode_len(limit.max + 1);
+        let fork_context = Arc::new(fork_context());
+        let mut codec = SSZSnappyOutboundCodec::<Spec>::new(
+            protocol_id.clone(),
+            1_048_576,
+            fork_context.clone(),
+        );
+        assert_eq!(codec.decode(&mut max).unwrap_err(), RPCError::InvalidData);
+
+        let mut min = encode_len(limit.min - 1);
+        let mut codec = SSZSnappyOutboundCodec::<Spec>::new(
+            protocol_id.clone(),
+            1_048_576,
+            fork_context.clone(),
+        );
+        assert_eq!(codec.decode(&mut min).unwrap_err(), RPCError::InvalidData);
+
+        // Request limits
+        let limit = protocol_id.rpc_request_limits();
+        let mut max = encode_len(limit.max + 1);
+        let mut codec = SSZSnappyOutboundCodec::<Spec>::new(
+            protocol_id.clone(),
+            1_048_576,
+            fork_context.clone(),
+        );
+        assert_eq!(codec.decode(&mut max).unwrap_err(), RPCError::InvalidData);
+
+        let mut min = encode_len(limit.min - 1);
+        let mut codec = SSZSnappyOutboundCodec::<Spec>::new(protocol_id, 1_048_576, fork_context);
+        assert_eq!(codec.decode(&mut min).unwrap_err(), RPCError::InvalidData);
+    }
+}

beacon_node/lighthouse_network/src/rpc/codec/mod.rs

@@ -0,0 +1,65 @@
+pub(crate) mod base;
+pub(crate) mod ssz_snappy;
+
+use self::base::{BaseInboundCodec, BaseOutboundCodec};
+use self::ssz_snappy::{SSZSnappyInboundCodec, SSZSnappyOutboundCodec};
+use crate::rpc::protocol::RPCError;
+use crate::rpc::{InboundRequest, OutboundRequest, RPCCodedResponse};
+use libp2p::bytes::BytesMut;
+use tokio_util::codec::{Decoder, Encoder};
+use types::EthSpec;
+
+// Known types of codecs
+pub enum InboundCodec<TSpec: EthSpec> {
+    SSZSnappy(BaseInboundCodec<SSZSnappyInboundCodec<TSpec>, TSpec>),
+}
+
+pub enum OutboundCodec<TSpec: EthSpec> {
+    SSZSnappy(BaseOutboundCodec<SSZSnappyOutboundCodec<TSpec>, TSpec>),
+}
+
+impl<T: EthSpec> Encoder<RPCCodedResponse<T>> for InboundCodec<T> {
+    type Error = RPCError;
+
+    fn encode(&mut self, item: RPCCodedResponse<T>, dst: &mut BytesMut) -> Result<(), Self::Error> {
+        match self {
+            InboundCodec::SSZSnappy(codec) => codec.encode(item, dst),
+        }
+    }
+}
+
+impl<TSpec: EthSpec> Decoder for InboundCodec<TSpec> {
+    type Item = InboundRequest<TSpec>;
+    type Error = RPCError;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        match self {
+            InboundCodec::SSZSnappy(codec) => codec.decode(src),
+        }
+    }
+}
+
+impl<TSpec: EthSpec> Encoder<OutboundRequest<TSpec>> for OutboundCodec<TSpec> {
+    type Error = RPCError;
+
+    fn encode(
+        &mut self,
+        item: OutboundRequest<TSpec>,
+        dst: &mut BytesMut,
+    ) -> Result<(), Self::Error> {
+        match self {
+            OutboundCodec::SSZSnappy(codec) => codec.encode(item, dst),
+        }
+    }
+}
+
+impl<T: EthSpec> Decoder for OutboundCodec<T> {
+    type Item = RPCCodedResponse<T>;
+    type Error = RPCError;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        match self {
+            OutboundCodec::SSZSnappy(codec) => codec.decode(src),
+        }
+    }
+}