generate-wire.py: generate chain_hash fields as sha256_double.

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

lightningd/opening/opening.c

@@ -243,7 +243,7 @@ static u8 *funder_channel(struct state *state,
 			      1000 * state->funding_satoshis);
 
 	msg = towire_open_channel(state,
-				  &state->chainparams->genesis_blockhash.sha,
+				  &state->chainparams->genesis_blockhash,
 				  &channel_id,
 				  state->funding_satoshis, state->push_msat,
 				  state->localconf.dust_limit_satoshis,
@@ -479,7 +479,7 @@ static u8 *fundee_channel(struct state *state,
 	 * `delayed_payment_basepoint` are not valid DER-encoded compressed
 	 * secp256k1 pubkeys.
 	 */
-	if (!fromwire_open_channel(peer_msg, NULL, &chain_hash.sha, &channel_id,
+	if (!fromwire_open_channel(peer_msg, NULL, &chain_hash, &channel_id,
 				   &state->funding_satoshis, &state->push_msat,
 				   &state->remoteconf->dust_limit_satoshis,
 				   &state->remoteconf->max_htlc_value_in_flight_msat,

tools/generate-wire.py

@@ -17,6 +17,7 @@ type2size = {
     'struct preimage': 32,
     'struct pubkey': 33,
     'struct sha256': 32,
+    'struct sha256_double': 32,
     'u64': 8,
     'u32': 4,
     'u16': 2,
@@ -76,6 +77,7 @@ partialtypemap = {
     'signature': FieldType('secp256k1_ecdsa_signature'),
     'features': FieldType('u8'),
     'channel_id': FieldType('struct channel_id'),
+    'chain_hash': FieldType('struct sha256_double'),
     'pad': FieldType('pad'),
 }
 

wire/test/run-peer-wire.c

@@ -164,7 +164,7 @@ struct msg_node_announcement {
 	u8 *addresses;
 };
 struct msg_open_channel {
-	struct sha256 chain_hash;
+	struct sha256_double chain_hash;
 	struct channel_id temporary_channel_id;
 	u64 funding_satoshis;
 	u64 push_msat;