Split NetworkGraph message handling fns into unsigned and signed

This takes the now-public `NetworkGraph` message handling functions
and splits them all into two methods - one which takes a required
Secp256k1 context and verifies signatures and one which takes only
the unsigned part of the message and does not take a Secp256k1
context.

This both clarifies the public API as well as simplifies it, all
without duplicating code.

Finally, this adds an assertion in the Router fuzzer to make sure
the constants used for message deserialization are correct.

Author: TheBlueMatt

fuzz/src/router.rs

@@ -11,8 +11,6 @@ use bitcoin::blockdata::script::Builder;
 use bitcoin::blockdata::transaction::TxOut;
 use bitcoin::hash_types::BlockHash;
 
-use bitcoin::secp256k1;
-
 use lightning::chain;
 use lightning::ln::channelmanager::ChannelDetails;
 use lightning::ln::features::InitFeatures;
@@ -120,7 +118,10 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 		($MsgType: path, $len: expr) => {{
 			let mut reader = ::std::io::Cursor::new(get_slice!($len));
 			match <$MsgType>::read(&mut reader) {
-				Ok(msg) => msg,
+				Ok(msg) => {
+					assert_eq!(reader.position(), $len as u64);
+					msg
+				},
 				Err(e) => match e {
 					msgs::DecodeError::UnknownVersion => return,
 					msgs::DecodeError::UnknownRequiredFeature => return,
@@ -134,10 +135,10 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 	}
 
 	macro_rules! decode_msg_with_len16 {
-		($MsgType: path, $begin_len: expr, $excess: expr) => {
+		($MsgType: path, $excess: expr) => {
 			{
-				let extra_len = slice_to_be16(&get_slice_nonadvancing!($begin_len as usize + 2)[$begin_len..$begin_len + 2]);
-				decode_msg!($MsgType, $begin_len as usize + 2 + (extra_len as usize) + $excess)
+				let extra_len = slice_to_be16(get_slice_nonadvancing!(2));
+				decode_msg!($MsgType, 2 + (extra_len as usize) + $excess)
 			}
 		}
 	}
@@ -162,29 +163,29 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 	loop {
 		match get_slice!(1)[0] {
 			0 => {
-				let start_len = slice_to_be16(&get_slice_nonadvancing!(64 + 2)[64..64 + 2]) as usize;
-				let addr_len = slice_to_be16(&get_slice_nonadvancing!(64+start_len+2 + 74)[64+start_len+2 + 72..64+start_len+2 + 74]);
+				let start_len = slice_to_be16(&get_slice_nonadvancing!(2)[0..2]) as usize;
+				let addr_len = slice_to_be16(&get_slice_nonadvancing!(start_len+2 + 74)[start_len+2 + 72..start_len+2 + 74]);
 				if addr_len > (37+1)*4 {
 					return;
 				}
-				let msg = decode_msg_with_len16!(msgs::NodeAnnouncement, 64, 288);
-				node_pks.insert(msg.contents.node_id);
-				let _ = net_graph.update_node_from_announcement::<secp256k1::VerifyOnly>(&msg, None);
+				let msg = decode_msg_with_len16!(msgs::UnsignedNodeAnnouncement, 288);
+				node_pks.insert(msg.node_id);
+				let _ = net_graph.update_node_from_unsigned_announcement(&msg);
 			},
 			1 => {
-				let msg = decode_msg_with_len16!(msgs::ChannelAnnouncement, 64*4, 32+8+33*4);
-				node_pks.insert(msg.contents.node_id_1);
-				node_pks.insert(msg.contents.node_id_2);
-				let _ = net_graph.update_channel_from_announcement::<secp256k1::VerifyOnly, &FuzzChainSource>(&msg, &None, None);
+				let msg = decode_msg_with_len16!(msgs::UnsignedChannelAnnouncement, 32+8+33*4);
+				node_pks.insert(msg.node_id_1);
+				node_pks.insert(msg.node_id_2);
+				let _ = net_graph.update_channel_from_unsigned_announcement::<&FuzzChainSource>(&msg, &None);
 			},
 			2 => {
-				let msg = decode_msg_with_len16!(msgs::ChannelAnnouncement, 64*4, 32+8+33*4);
-				node_pks.insert(msg.contents.node_id_1);
-				node_pks.insert(msg.contents.node_id_2);
-				let _ = net_graph.update_channel_from_announcement::<secp256k1::VerifyOnly, &FuzzChainSource>(&msg, &Some(&FuzzChainSource { input: Arc::clone(&input) }), None);
+				let msg = decode_msg_with_len16!(msgs::UnsignedChannelAnnouncement, 32+8+33*4);
+				node_pks.insert(msg.node_id_1);
+				node_pks.insert(msg.node_id_2);
+				let _ = net_graph.update_channel_from_unsigned_announcement(&msg, &Some(&FuzzChainSource { input: Arc::clone(&input) }));
 			},
 			3 => {
-				let _ = net_graph.update_channel(&decode_msg!(msgs::ChannelUpdate, 136), None);
+				let _ = net_graph.update_channel_unsigned(&decode_msg!(msgs::UnsignedChannelUpdate, 72));
 			},
 			4 => {
 				let short_channel_id = slice_to_be64(get_slice!(8));