validate header version during header deserialization

core/src/core/block.rs

@@ -22,7 +22,7 @@ use std::fmt;
 use std::iter::FromIterator;
 use std::sync::Arc;
 
-use crate::consensus::{reward, REWARD};
+use crate::consensus::{self, reward, REWARD};
 use crate::core::committed::{self, Committed};
 use crate::core::compact_block::{CompactBlock, CompactBlockBody};
 use crate::core::hash::{DefaultHashable, Hash, Hashed, ZERO_HASH};
@@ -300,6 +300,14 @@ impl Readable for BlockHeader {
 			return Err(ser::Error::CorruptedData);
 		}
 
+		// Check the block version before proceeding any further.
+		// We want to do this here because blocks can be pretty large
+		// and we want to halt processing as early as possible.
+		// If we receive an invalid block version then the peer is not on our hard-fork.
+		if !consensus::valid_header_version(height, version) {
+			return Err(ser::Error::InvalidBlockVersion);
+		}
+
 		Ok(BlockHeader {
 			version,
 			height,

core/src/ser.rs

@@ -65,6 +65,8 @@ pub enum Error {
 	SortError,
 	/// Inputs/outputs/kernels must be unique.
 	DuplicateError,
+	/// Block header version (hard-fork schedule).
+	InvalidBlockVersion,
 }
 
 impl From<io::Error> for Error {
@@ -87,6 +89,7 @@ impl fmt::Display for Error {
 			Error::DuplicateError => f.write_str("duplicate"),
 			Error::TooLargeReadErr => f.write_str("too large read"),
 			Error::HexError(ref e) => write!(f, "hex error {:?}", e),
+			Error::InvalidBlockVersion => f.write_str("invalid block version"),
 		}
 	}
 }
@@ -109,6 +112,7 @@ impl error::Error for Error {
 			Error::DuplicateError => "duplicate error",
 			Error::TooLargeReadErr => "too large read",
 			Error::HexError(_) => "hex error",
+			Error::InvalidBlockVersion => "invalid block version",
 		}
 	}
 }