channeld: hand in chain_hash.

This will be needed for gossip messages.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/channel/channel.c

@@ -83,6 +83,7 @@ struct peer {
 	 */
 	u64 htlc_id;
 
+	struct sha256_double chain_hash;
 	struct channel_id channel_id;
 	struct channel *channel;
 
@@ -2004,6 +2005,7 @@ static void init_channel(struct peer *peer)
 
 	msg = wire_sync_read(peer, REQ_FD);
 	if (!fromwire_channel_init(peer, msg, NULL,
+				   &peer->chain_hash,
 				   &funding_txid, &funding_txout,
 				   &funding_satoshi,
 				   &peer->conf[LOCAL], &peer->conf[REMOTE],

lightningd/channel/channel_wire.csv

@@ -22,6 +22,7 @@ channel_normal_operation,1001
 
 # Begin!  (passes gossipd-client fd)
 channel_init,1
+channel_init,,chain_hash,struct sha256_double
 channel_init,,funding_txid,struct sha256_double
 channel_init,,funding_txout,2
 channel_init,,funding_satoshi,8

lightningd/peer_control.c

@@ -1643,6 +1643,7 @@ static bool peer_start_channeld(struct peer *peer,
 		shutdown_scriptpubkey = NULL;
 
 	initmsg = towire_channel_init(tmpctx,
+				      &peer->ld->chainparams->genesis_blockhash,
 				      peer->funding_txid,
 				      peer->funding_outnum,
 				      peer->funding_satoshi,