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    use hash::H32;
    use ser::{Serializable, Stream, Reader};
    use crypto::checksum;
    use network::Magic;
    use common::Command;
    use Error;

    #[derive(Debug, PartialEq)]
    pub struct MessageHeader {
    	pub magic: Magic,
    	pub command: Command,
    	pub len: u32,
    	pub checksum: H32,
    }

    impl MessageHeader {
    	pub fn for_data(magic: Magic, command: Command, data: &[u8]) -> Self {
    		MessageHeader {
    			magic: magic,
    			command: command,
    			len: data.len() as u32,
    			checksum: checksum(data),
    		}
    	}
    }

    impl MessageHeader {
    	pub fn deserialize(data: &[u8], expected: Magic) -> Result<Self, Error> {
    		if data.len() != 24 {
    			return Err(Error::Deserialize);
    		}

    		let mut reader = Reader::new(data);
    		let magic: u32 = try!(reader.read());
    		let magic = Magic::from(magic);
    		if expected != magic {
    			return Err(Error::InvalidMagic);
    		}

    		let header = MessageHeader {
    			magic: magic,
    			command: try!(reader.read()),
    			len: try!(reader.read()),
    			checksum: try!(reader.read()),
    		};

    		Ok(header)
    	}
    }

    impl Serializable for MessageHeader {
    	fn serialize(&self, stream: &mut Stream) {
    		stream
    			.append(&self.magic)
    			.append(&self.command)
    			.append(&self.len)
    			.append(&self.checksum);
    	}
    }

    #[cfg(test)]
    mod tests {
    	use bytes::Bytes;
    	use ser::serialize;
    	use network::{Network, ConsensusFork};
    	use super::MessageHeader;

    	#[test]
    	fn test_message_header_serialization() {
    		let expected = "f9beb4d96164647200000000000000001f000000ed52399b".into();
    		let header = MessageHeader {
    			magic: Network::Mainnet.magic(&ConsensusFork::BitcoinCore),
    			command: "addr".into(),
    			len: 0x1f,
    			checksum: "ed52399b".into(),
    		};

    		assert_eq!(serialize(&header), expected);
    	}

    	#[test]
    	fn test_message_header_deserialization() {
    		let raw: Bytes = "f9beb4d96164647200000000000000001f000000ed52399b".into();
    		let expected = MessageHeader {
    			magic: Network::Mainnet.magic(&ConsensusFork::BitcoinCore),
    			command: "addr".into(),
    			len: 0x1f,
    			checksum: "ed52399b".into(),
    		};

    		assert_eq!(expected, MessageHeader::deserialize(&raw, Network::Mainnet.magic(&ConsensusFork::BitcoinCore)).unwrap());
    	}
    }

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