Move state/block.rs into own mod, add SszBlock

lighthouse/state/block/mod.rs

@@ -0,0 +1,11 @@
+extern crate blake2_rfc;
+
+use super::ssz;
+use super::utils;
+use super::attestation_record;
+
+mod block;
+mod ssz_block;
+
+pub use self::block::Block;
+pub use self::ssz_block::SszBlock;

lighthouse/state/block/ssz_block.rs

@@ -0,0 +1,90 @@
+use super::ssz::decode::{
+    decode_length,
+    Decodable,
+};
+use super::utils::hash::canonical_hash;
+
+pub enum BlockValidatorError {
+    SszInvalid,
+    BadPowHash,
+    SlotTooLow,
+    SlotTooHigh,
+}
+
+const LENGTH_BYTES: usize = 4;
+const MIN_SSZ_BLOCK_LENGTH: usize = {
+    32 +    // parent_hash
+    8 +     // slot_number
+    32 +    // randao_reveal
+    LENGTH_BYTES +     // attestations (assuming zero)
+    32 +    // pow_chain_ref
+    32 +    // active_state_root
+    32      // crystallized_state_root
+};
+const MAX_SSZ_BLOCK_LENGTH: usize = MIN_SSZ_BLOCK_LENGTH + 2^24;
+
+
+pub struct SszBlock<'a> {
+    ssz: &'a [u8],
+    attestation_len: usize,
+}
+
+impl<'a> SszBlock<'a> {
+    pub fn from_vec(vec: &'a Vec<u8>)
+        -> Result<Self, BlockValidatorError>
+    {
+        if vec.len() < MIN_SSZ_BLOCK_LENGTH {
+            return Err(BlockValidatorError::SszInvalid);
+        }
+        if vec.len() > MAX_SSZ_BLOCK_LENGTH {
+            return Err(BlockValidatorError::SszInvalid);
+        }
+        let attestation_len = decode_length(&vec[72..76], LENGTH_BYTES)
+            .map_err(|_| BlockValidatorError::SszInvalid)?;
+        // Is the length adequate now we know now many attestation
+        // records exist?
+        if vec.len() < (76 + attestation_len + 96) {
+            return Err(BlockValidatorError::SszInvalid);
+        }
+        Ok(Self{
+            ssz: &vec[..],
+            attestation_len
+        })
+    }
+
+    pub fn block_hash(&self) -> Vec<u8> {
+        canonical_hash(self.ssz)
+    }
+
+    pub fn parent_hash(&self) -> &[u8] {
+        &self.ssz[0..32]
+    }
+
+    pub fn slot_number(&self) -> u64 {
+        u64::ssz_decode(&self.ssz[32..40]).unwrap()
+    }
+
+    pub fn randao_reveal(&self) -> &[u8] {
+        &self.ssz[40..72]
+    }
+
+    pub fn attestations(&self) -> &[u8] {
+        let start = 72 + LENGTH_BYTES;
+        &self.ssz[start..(start + self.attestation_len)]
+    }
+
+    pub fn pow_chain_ref(&self) -> &[u8] {
+        let len = self.ssz.len();
+        &self.ssz[(len - 96)..(len - 64)]
+    }
+
+    pub fn act_state_root(&self) -> &[u8] {
+        let len = self.ssz.len();
+        &self.ssz[(len - 64)..(len - 32)]
+    }
+
+    pub fn cry_state_root(&self) -> &[u8] {
+        let len = self.ssz.len();
+        &self.ssz[(len - 32)..(len)]
+    }
+}