allow EhereumNode network state override

eth/p2p.nim

@@ -8,7 +8,7 @@
 {.push raises: [Defect].}
 
 import
-  std/[tables, algorithm, random],
+  std/[tables, algorithm, random, typetraits, strutils],
   chronos, chronos/timer, chronicles,
   ./keys, ./p2p/private/p2p_types,
   ./p2p/[kademlia, discovery, enode, peer_pool, rlpx]
@@ -16,19 +16,59 @@ import
 export
   p2p_types, rlpx, enode, kademlia
 
-proc addCapability*(node: var EthereumNode, p: ProtocolInfo) =
+proc addCapability*(node: var EthereumNode,
+                    p: ProtocolInfo,
+                    networkState: RootRef = nil) =
   doAssert node.connectionState == ConnectionState.None
 
   let pos = lowerBound(node.protocols, p, rlpx.cmp)
   node.protocols.insert(p, pos)
   node.capabilities.insert(p.asCapability, pos)
 
-  if p.networkStateInitializer != nil:
+  if p.networkStateInitializer != nil and networkState.isNil:
     node.protocolStates[p.index] = p.networkStateInitializer(node)
 
+  if networkState.isNil.not:
+    node.protocolStates[p.index] = networkState
+
 template addCapability*(node: var EthereumNode, Protocol: type) =
   addCapability(node, Protocol.protocolInfo)
 
+template addCapability*(node: var EthereumNode,
+                        Protocol: type,
+                        networkState: untyped) =
+  mixin NetworkState
+  type
+    ParamType = type(networkState)
+
+  when ParamType isnot Protocol.NetworkState:
+    const errMsg = "`$1` is not compatible with `$2`" % [
+      name(ParamType), name(Protocol.NetworkState)]
+    {. error: errMsg .}
+
+  addCapability(node, Protocol.protocolInfo, 
+    cast[RootRef](networkState))
+
+proc replaceNetworkState*(node: var EthereumNode,
+                          p: ProtocolInfo,
+                          networkState: RootRef) =
+  node.protocolStates[p.index] = networkState
+
+template replaceNetworkState*(node: var EthereumNode,
+                              Protocol: type,
+                              networkState: untyped) =
+  mixin NetworkState
+  type
+    ParamType = type(networkState)
+
+  when ParamType isnot Protocol.NetworkState:
+    const errMsg = "`$1` is not compatible with `$2`" % [
+      name(ParamType), name(Protocol.NetworkState)]
+    {. error: errMsg .}
+
+  replaceNetworkState(node, Protocol.protocolInfo, 
+    cast[RootRef](networkState))
+
 proc newEthereumNode*(
     keys: KeyPair,
     address: Address,

tests/p2p/test_protocol_handlers.nim

@@ -86,3 +86,9 @@ suite "Testing protocol handlers":
       peer.isNil == true
       # To check if the disconnection handler did not run
       node1.protocolState(hah).count == 0
+
+  test "Override network state":
+    let rng = newRng()
+    var node = setupTestNode(rng, hah)
+    node.addCapability(hah, network())
+    node.replaceNetworkState(hah, network())