From 9989f2fe560606383352e5063511b3f5791f6dbc Mon Sep 17 00:00:00 2001
From: Mamy Ratsimbazafy <mratsim@users.noreply.github.com>
Date: Thu, 22 Nov 2018 11:17:05 +0100
Subject: [PATCH] "Stub" hashSSZ function for BeaconBlock (#18)

* FIx hash_ssz in the generic case

* Add a stub hash function for BeaconBlocks
---
 beacon_chain/datatypes.nim |  6 ++--
 beacon_chain/ssz.nim       | 58 ++++++++++++++++++++++++++++++++++++--
 tests/test_ssz.nim         |  5 ++++
 3 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/beacon_chain/datatypes.nim b/beacon_chain/datatypes.nim
index f5bd03695..5f0350695 100644
--- a/beacon_chain/datatypes.nim
+++ b/beacon_chain/datatypes.nim
@@ -44,7 +44,7 @@ type
     state_root*: Blake2_256_Digest                 # State root
     attestations*: seq[AttestationRecord]          # Attestations
     specials*: seq[SpecialRecord]                  # Specials (e.g. logouts, penalties)
-    proposer_signature*: Signature                 # Proposer signature
+    proposer_signature*: BLSSig                    # Proposer signature
 
   ProposalSignedData* = object
     fork_version*: uint64                         # Fork version
@@ -87,8 +87,8 @@ type
                                                   # Root of data between last hash and this one
     attester_bitfield*: IntSet                    # Attester participation bitfield (1 bit per attester)
     justified_slot*: uint64                       # Slot of last justified beacon block
-    justified_block_hash: Blake2_256_Digest       # Hash of last justified beacon block
-    aggregate_sig*: Signature                     # BLS aggregate signature
+    justified_block_hash*: Blake2_256_Digest      # Hash of last justified beacon block
+    aggregate_sig*: BLSSig                        # BLS aggregate signature
 
   BeaconState* = object
     validator_set_change_slot*: uint64                     # Slot of last validator set change
diff --git a/beacon_chain/ssz.nim b/beacon_chain/ssz.nim
index 344a7cdf8..a4f7c2856 100644
--- a/beacon_chain/ssz.nim
+++ b/beacon_chain/ssz.nim
@@ -9,7 +9,12 @@
 # See https://github.com/ethereum/beacon_chain/issues/100
 # and https://github.com/ethereum/beacon_chain/tree/master/ssz
 
-import ./datatypes, eth_common, endians, typetraits, options, nimcrypto
+import
+  endians, typetraits, options, algorithm,
+  eth_common, nimcrypto,
+  ./datatypes
+
+from milagro_crypto import getRaw
 
 # ################### Helper functions ###################################
 
@@ -206,7 +211,7 @@ func hashSSZ*(x: ShardAndCommittee): array[32, byte] =
     h.update hashSSZ(x.shard_id)
     h.update merkleHash(x.committee)
 
-func hashSSZ*[T](x: T): array[32, byte] =
+func hashSSZ*[T: not enum](x: T): array[32, byte] =
   when T is seq:
     ## Sequences are tree-hashed
     return merkleHash(x)
@@ -215,12 +220,59 @@ func hashSSZ*[T](x: T): array[32, byte] =
     # XXX could probaby compile-time-macro-sort fields...
     var fields: seq[tuple[name: string, value: seq[byte]]]
     for name, field in x.fieldPairs:
-      fields.add (name, hashSSZ(field))
+      fields.add (name, @(hashSSZ(field)))
 
     return withHash:
       for name, value in fields.sortedByIt(it.name):
         h.update hashSSZ(value.value)
 
+# #################################
+# HashSSZ not part of official spec
+func hashSSZ*(x: enum): array[32, byte] =
+  ## TODO - Warning ⚠️: not part of the spec
+  ## as of https://github.com/ethereum/beacon_chain/pull/133/files
+  ## This is a "stub" needed for BeaconBlock hashing
+  static: assert x.sizeof == 1 # Check that the enum fits in 1 byte
+  withHash:
+    h.update [uint8 x]
+
+func hashSSZ*(x: BLSsig): array[32, byte] =
+  ## TODO - Warning ⚠️: not part of the spec
+  ## as of https://github.com/ethereum/beacon_chain/pull/133/files
+  ## This is a "stub" needed for BeaconBlock hashing
+  x.getraw().hash()
+
+func hashSSZ*(x: AttestationRecord): array[32, byte] =
+  ## TODO - Warning ⚠️: not part of the spec
+  ## as of https://github.com/ethereum/beacon_chain/pull/133/files
+  ## This is a "stub" needed for BeaconBlock hashing
+  withHash:
+    h.update hashSSZ(x.slot)
+    h.update hashSSZ(x.shard)
+    h.update hashSSZ(x.oblique_parent_hashes)
+    h.update hashSSZ(x.shard_block_hash)
+    h.update hashSSZ(x.last_crosslink_hash)
+    h.update hashSSZ(x.shard_block_combined_data_root)
+    # h.update hashSSZ(attester_bitfield) # TODO - the bitfield as a specific serialisation format
+    h.update hashSSZ(x.justified_slot)
+    h.update hashSSZ(x.justified_block_hash)
+    h.update hashSSZ(x.aggregate_sig)
+
+func hashSSZ*(x: BeaconBlock): array[32, byte] =
+  ## TODO - Warning ⚠️: not part of the spec
+  ## as of https://github.com/ethereum/beacon_chain/pull/133/files
+  ## This is a "stub" needed for fork_choice_rule
+  ## and networking
+  withHash:
+    h.update hashSSZ(x.slot)
+    h.update hashSSZ(x.randao_reveal)
+    h.update hashSSZ(x.candidate_pow_receipt_root)
+    h.update hashSSZ(x.ancestor_hashes)
+    h.update hashSSZ(x.state_root)
+    h.update hashSSZ(x.attestations)
+    h.update hashSSZ(x.specials)
+    h.update hashSSZ(x.proposer_signature)
+
 # ################### Tree hash ###################################
 
 func merkleHash[T](lst: seq[T]): array[32, byte] =
diff --git a/tests/test_ssz.nim b/tests/test_ssz.nim
index e301dc95a..83944170e 100644
--- a/tests/test_ssz.nim
+++ b/tests/test_ssz.nim
@@ -70,6 +70,11 @@ suite "Tree hashing":
     let sc = ShardAndCommittee()
     check: hashSSZ(sc).len > 0
 
+  test "Hash BeaconBlock":
+    ## TODO: Test genesis hash when spec is updated
+    let bb = BeaconBlock()
+    check: hashSSZ(bb).len > 0
+
   test "Hash integer":
     check: hashSSZ(0x01'u32) == [0'u8, 0, 0, 1] # big endian!
     check: hashSSZ(Uint24(0x01)) == [0'u8, 0, 1] # big endian!