bitcoin: create new wrapper type bitcoin_blkid, log backward endianness.

It's just a sha256_double, but importantly when we convert it to a string (in type_to_string, which is used in logging) we use bitcoin_blkid_to_hex() so it's reversed as people expect. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2025-12-19 07:04:22 +01:00 · 2017-12-18 17:14:10 +10:30
parent 0237e0b28c
commit 810abb6b21
27 changed files with 92 additions and 73 deletions
--- a/bitcoin/block.c
+++ b/bitcoin/block.c
@@ -2,6 +2,7 @@
 #include "bitcoin/pullpush.h"
 #include "bitcoin/tx.h"
 #include <ccan/str/hex/hex.h>
+#include <common/type_to_string.h>

 /* Encoding is <blockhdr> <varint-num-txs> <tx>... */
 struct bitcoin_block *bitcoin_block_from_hex(const tal_t *ctx,
@@ -38,20 +39,21 @@ struct bitcoin_block *bitcoin_block_from_hex(const tal_t *ctx,
 	return b;
 }

+/* We do the same hex-reversing crud as txids. */
 bool bitcoin_blkid_from_hex(const char *hexstr, size_t hexstr_len,
-			    struct sha256_double *blockid)
+			    struct bitcoin_blkid *blockid)
 {
 	struct bitcoin_txid fake_txid;
 	if (!bitcoin_txid_from_hex(hexstr, hexstr_len, &fake_txid))
 		return false;
-	*blockid = fake_txid.shad;
+	blockid->shad = fake_txid.shad;
 	return true;
 }

-bool bitcoin_blkid_to_hex(const struct sha256_double *blockid,
+bool bitcoin_blkid_to_hex(const struct bitcoin_blkid *blockid,
 			  char *hexstr, size_t hexstr_len)
 {
 	struct bitcoin_txid fake_txid;
-	fake_txid.shad = *blockid;
+	fake_txid.shad = blockid->shad;
 	return bitcoin_txid_to_hex(&fake_txid, hexstr, hexstr_len);
 }
--- a/bitcoin/block.h
+++ b/bitcoin/block.h
@@ -7,9 +7,13 @@
 #include <ccan/tal/tal.h>
 #include <stdbool.h>

+struct bitcoin_blkid {
+	struct sha256_double shad;
+};
+
 struct bitcoin_block_hdr {
 	le32 version;
-	struct sha256_double prev_hash;
+	struct bitcoin_blkid prev_hash;
 	struct sha256_double merkle_hash;
 	le32 timestamp;
 	le32 target;
@@ -27,9 +31,9 @@ struct bitcoin_block *bitcoin_block_from_hex(const tal_t *ctx,

 /* Parse hex string to get blockid (reversed, a-la bitcoind). */
 bool bitcoin_blkid_from_hex(const char *hexstr, size_t hexstr_len,
-			    struct sha256_double *blockid);
+			    struct bitcoin_blkid *blockid);

 /* Get hex string of blockid (reversed, a-la bitcoind). */
-bool bitcoin_blkid_to_hex(const struct sha256_double *blockid,
+bool bitcoin_blkid_to_hex(const struct bitcoin_blkid *blockid,
 			  char *hexstr, size_t hexstr_len);
 #endif /* LIGHTNING_BITCOIN_BLOCK_H */
--- a/bitcoin/chainparams.c
+++ b/bitcoin/chainparams.c
@@ -7,7 +7,7 @@ const struct chainparams networks[] = {
    {.index = 0,
     .network_name = "bitcoin",
     .bip173_name = "bc",
-     .genesis_blockhash = {{.u.u8 = {0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, 0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f, 0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c, 0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+     .genesis_blockhash = {{{.u.u8 = {0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, 0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f, 0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c, 0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00}}}},
     .rpc_port = 8332,
     .cli = "bitcoin-cli",
     .cli_args = NULL,
@@ -16,7 +16,7 @@ const struct chainparams networks[] = {
    {.index = 1,
     .network_name = "regtest",
     .bip173_name = "tb",
-     .genesis_blockhash = {{.u.u8 = {0x06, 0x22, 0x6e, 0x46, 0x11, 0x1a, 0x0b, 0x59, 0xca, 0xaf, 0x12, 0x60, 0x43, 0xeb, 0x5b, 0xbf, 0x28, 0xc3, 0x4f, 0x3a, 0x5e, 0x33, 0x2a, 0x1f, 0xc7, 0xb2, 0xb7, 0x3c, 0xf1, 0x88, 0x91, 0x0f}}},
+     .genesis_blockhash = {{{.u.u8 = {0x06, 0x22, 0x6e, 0x46, 0x11, 0x1a, 0x0b, 0x59, 0xca, 0xaf, 0x12, 0x60, 0x43, 0xeb, 0x5b, 0xbf, 0x28, 0xc3, 0x4f, 0x3a, 0x5e, 0x33, 0x2a, 0x1f, 0xc7, 0xb2, 0xb7, 0x3c, 0xf1, 0x88, 0x91, 0x0f}}}},
     .rpc_port = 18332,
     .cli = "bitcoin-cli",
     .cli_args = "-regtest",
@@ -25,7 +25,7 @@ const struct chainparams networks[] = {
    {.index = 2,
     .network_name = "testnet",
     .bip173_name = "tb",
-     .genesis_blockhash = {{.u.u8 = {0x43, 0x49, 0x7f, 0xd7, 0xf8, 0x26, 0x95, 0x71, 0x08, 0xf4, 0xa3, 0x0f, 0xd9, 0xce, 0xc3, 0xae, 0xba, 0x79, 0x97, 0x20, 0x84, 0xe9, 0x0e, 0xad, 0x01, 0xea, 0x33, 0x09, 0x00, 0x00, 0x00, 0x00}}},
+     .genesis_blockhash = {{{.u.u8 = {0x43, 0x49, 0x7f, 0xd7, 0xf8, 0x26, 0x95, 0x71, 0x08, 0xf4, 0xa3, 0x0f, 0xd9, 0xce, 0xc3, 0xae, 0xba, 0x79, 0x97, 0x20, 0x84, 0xe9, 0x0e, 0xad, 0x01, 0xea, 0x33, 0x09, 0x00, 0x00, 0x00, 0x00}}}},
     .rpc_port = 18332,
     .cli = "bitcoin-cli",
     .cli_args = "-testnet",
@@ -34,7 +34,7 @@ const struct chainparams networks[] = {
    {.index = 3,
     .network_name = "litecoin",
     .bip173_name = "ltc",
-     .genesis_blockhash = {{.u.u8 = {0xe2, 0xbf, 0x04, 0x7e, 0x7e, 0x5a, 0x19, 0x1a, 0xa4, 0xef, 0x34, 0xd3, 0x14, 0x97, 0x9d, 0xc9, 0x98, 0x6e, 0x0f, 0x19, 0x25, 0x1e, 0xda, 0xba, 0x59, 0x40, 0xfd, 0x1f, 0xe3, 0x65, 0xa7, 0x12 }}},
+     .genesis_blockhash = {{{.u.u8 = {0xe2, 0xbf, 0x04, 0x7e, 0x7e, 0x5a, 0x19, 0x1a, 0xa4, 0xef, 0x34, 0xd3, 0x14, 0x97, 0x9d, 0xc9, 0x98, 0x6e, 0x0f, 0x19, 0x25, 0x1e, 0xda, 0xba, 0x59, 0x40, 0xfd, 0x1f, 0xe3, 0x65, 0xa7, 0x12 }}}},
     .rpc_port = 18332,
     .cli = "litecoin-cli",
     .cli_args = "",
--- a/bitcoin/chainparams.h
+++ b/bitcoin/chainparams.h
@@ -2,7 +2,7 @@
 #define LIGHTNING_BITCOIN_CHAINPARAMS_H

 #include "config.h"
-#include <bitcoin/shadouble.h>
+#include <bitcoin/block.h>
 #include <ccan/short_types/short_types.h>
 #include <stdbool.h>

@@ -10,7 +10,7 @@ struct chainparams {
 	const int index;
 	const char *network_name;
 	const char *bip173_name;
-	const struct sha256_double genesis_blockhash;
+	const struct bitcoin_blkid genesis_blockhash;
 	const int rpc_port;
 	const char *cli;
 	const char *cli_args;
--- a/bitcoin/shadouble.c
+++ b/bitcoin/shadouble.c
@@ -1,6 +1,5 @@
 #include "shadouble.h"
 #include <ccan/mem/mem.h>
-#include <common/type_to_string.h>

 void sha256_double(struct sha256_double *shadouble, const void *p, size_t len)
 {
@@ -13,5 +12,3 @@ void sha256_double_done(struct sha256_ctx *shactx, struct sha256_double *res)
 	sha256_done(shactx, &res->sha);
 	sha256(&res->sha, &res->sha, sizeof(res->sha));
 }
-
-REGISTER_TYPE_TO_HEXSTR(sha256_double);
--- a/channeld/channel.c
+++ b/channeld/channel.c
@@ -101,7 +101,7 @@ struct peer {
 	 */
 	u64 htlc_id;

-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct channel_id channel_id;
 	struct channel *channel;

--- a/channeld/channel_wire.csv
+++ b/channeld/channel_wire.csv
@@ -6,7 +6,7 @@ channel_normal_operation,11001

 # Begin!  (passes gossipd-client fd)
 channel_init,1000
-channel_init,,chain_hash,struct sha256_double
+channel_init,,chain_hash,struct bitcoin_blkid
 channel_init,,funding_txid,struct bitcoin_txid
 channel_init,,funding_txout,u16
 channel_init,,funding_satoshi,u64
--- a/common/type_to_string.h
+++ b/common/type_to_string.h
@@ -8,8 +8,8 @@
 /* This must match the type_to_string_ cases. */
 union printable_types {
 	const struct pubkey *pubkey;
-	const struct sha256_double *sha256_double;
 	const struct bitcoin_txid *bitcoin_txid;
+	const struct bitcoin_blkid *bitcoin_blkid;
 	const struct sha256 *sha256;
 	const struct ripemd160 *ripemd160;
 	const struct rel_locktime *rel_locktime;
--- a/gossipd/gossip.c
+++ b/gossipd/gossip.c
@@ -742,7 +742,7 @@ static void handle_local_add_channel(struct peer *peer, u8 *msg)
 {
 	struct routing_state *rstate = peer->daemon->rstate;
 	struct short_channel_id scid;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct pubkey remote_node_id;
 	u16 flags, cltv_expiry_delta, direction;
 	u32 fee_base_msat, fee_proportional_millionths;
@@ -759,7 +759,8 @@ static void handle_local_add_channel(struct peer *peer, u8 *msg)

 	if (!structeq(&chain_hash, &rstate->chain_hash)) {
 		status_trace("Received channel_announcement for unknown chain %s",
-			     type_to_string(msg, struct sha256_double,&chain_hash));
+			     type_to_string(msg, struct bitcoin_blkid,
+					    &chain_hash));
 		return;
 	}

@@ -1288,7 +1289,7 @@ static struct io_plan *gossip_init(struct daemon_conn *master,
 				   struct daemon *daemon,
 				   const u8 *msg)
 {
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	u16 port;

 	if (!fromwire_gossipctl_init(daemon, msg, NULL,
--- a/gossipd/gossip_wire.csv
+++ b/gossipd/gossip_wire.csv
@@ -4,7 +4,7 @@
 # Initialize the gossip daemon.
 gossipctl_init,3000
 gossipctl_init,,broadcast_interval,u32
-gossipctl_init,,chain_hash,struct sha256_double
+gossipctl_init,,chain_hash,struct bitcoin_blkid
 gossipctl_init,,id,struct pubkey
 # If non-zero, port to listen on.
 gossipctl_init,,port,u16
@@ -150,7 +150,7 @@ gossip_send_gossip,,gossip,len*u8
 # we can use it already.
 gossip_local_add_channel,3017
 gossip_local_add_channel,,short_channel_id,struct short_channel_id
-gossip_local_add_channel,,chain_hash,struct sha256_double
+gossip_local_add_channel,,chain_hash,struct bitcoin_blkid
 gossip_local_add_channel,,remote_node_id,struct pubkey
 gossip_local_add_channel,,flags,u16
 gossip_local_add_channel,,cltv_expiry_delta,u16
--- a/gossipd/routing.c
+++ b/gossipd/routing.c
@@ -35,7 +35,7 @@ static struct node_map *empty_node_map(const tal_t *ctx)
 }

 struct routing_state *new_routing_state(const tal_t *ctx,
-					const struct sha256_double *chain_hash,
+					const struct bitcoin_blkid *chain_hash,
 					const struct pubkey *local_id)
 {
 	struct routing_state *rstate = tal(ctx, struct routing_state);
@@ -503,7 +503,7 @@ bool handle_channel_announcement(
 	struct pubkey node_id_2;
 	struct pubkey bitcoin_key_1;
 	struct pubkey bitcoin_key_2;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct node_connection *c0, *c1;
 	const tal_t *tmpctx = tal_tmpctx(rstate);
 	u8 *features;
@@ -531,7 +531,7 @@ bool handle_channel_announcement(
 	if (!structeq(&chain_hash, &rstate->chain_hash)) {
 		status_trace("Received channel_announcement for unknown chain"
 			     " %s",
-			     type_to_string(tmpctx, struct sha256_double,
+			     type_to_string(tmpctx, struct bitcoin_blkid,
 					    &chain_hash));
 		tal_free(tmpctx);
 		return false;
@@ -603,7 +603,7 @@ void handle_channel_update(struct routing_state *rstate, const u8 *update)
 	u32 fee_base_msat;
 	u32 fee_proportional_millionths;
 	const tal_t *tmpctx = tal_tmpctx(rstate);
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	size_t len = tal_len(update);

 	serialized = tal_dup_arr(tmpctx, u8, update, len, 0);
@@ -623,7 +623,7 @@ void handle_channel_update(struct routing_state *rstate, const u8 *update)
 	 * specified chain. */
 	if (!structeq(&chain_hash, &rstate->chain_hash)) {
 		status_trace("Received channel_update for unknown chain %s",
-			     type_to_string(tmpctx, struct sha256_double,
+			     type_to_string(tmpctx, struct bitcoin_blkid,
 					    &chain_hash));
 		tal_free(tmpctx);
 		return;
--- a/gossipd/routing.h
+++ b/gossipd/routing.h
@@ -82,7 +82,7 @@ struct routing_state {

 	struct broadcast_state *broadcasts;

-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;

 	/* Our own ID so we can identify local channels */
 	struct pubkey local_id;
@@ -96,7 +96,7 @@ struct route_hop {
 };

 struct routing_state *new_routing_state(const tal_t *ctx,
-					const struct sha256_double *chain_hash,
+					const struct bitcoin_blkid *chain_hash,
 					const struct pubkey *local_id);

 /* Add a connection to the routing table, but do not mark it as usable
--- a/gossipd/test/run-bench-find_route.c
+++ b/gossipd/test/run-bench-find_route.c
@@ -49,10 +49,10 @@ struct broadcast_state *new_broadcast_state(tal_t *ctx UNNEEDED)

 /* AUTOGENERATED MOCKS START */
 /* Generated stub for fromwire_channel_announcement */
-bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
+bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
 { fprintf(stderr, "fromwire_channel_announcement called!\n"); abort(); }
 /* Generated stub for fromwire_channel_update */
-bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
+bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
 /* Generated stub for fromwire_node_announcement */
 bool fromwire_node_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, u8 **features UNNEEDED, u32 *timestamp UNNEEDED, struct pubkey *node_id UNNEEDED, u8 rgb_color[3] UNNEEDED, u8 alias[32] UNNEEDED, u8 **addresses UNNEEDED)
@@ -151,7 +151,7 @@ static void run(const char *name)

 int main(int argc, char *argv[])
 {
-	static const struct sha256_double zerohash;
+	static const struct bitcoin_blkid zerohash;
 	const tal_t *ctx = trc = tal_tmpctx(NULL);
 	struct routing_state *rstate;
 	size_t num_nodes = 100, num_runs = 1;
--- a/gossipd/test/run-find_route-specific.c
+++ b/gossipd/test/run-find_route-specific.c
@@ -20,10 +20,10 @@ struct broadcast_state *new_broadcast_state(tal_t *ctx UNNEEDED)

 /* AUTOGENERATED MOCKS START */
 /* Generated stub for fromwire_channel_announcement */
-bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
+bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
 { fprintf(stderr, "fromwire_channel_announcement called!\n"); abort(); }
 /* Generated stub for fromwire_channel_update */
-bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
+bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
 /* Generated stub for fromwire_node_announcement */
 bool fromwire_node_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, u8 **features UNNEEDED, u32 *timestamp UNNEEDED, struct pubkey *node_id UNNEEDED, u8 rgb_color[3] UNNEEDED, u8 alias[32] UNNEEDED, u8 **addresses UNNEEDED)
@@ -57,7 +57,7 @@ const void *trc;

 int main(void)
 {
-	static const struct sha256_double zerohash;
+	static const struct bitcoin_blkid zerohash;
 	const tal_t *ctx = trc = tal_tmpctx(NULL);
 	struct node_connection *nc;
 	struct routing_state *rstate;
--- a/gossipd/test/run-find_route.c
+++ b/gossipd/test/run-find_route.c
@@ -13,10 +13,10 @@ struct broadcast_state *new_broadcast_state(tal_t *ctx UNNEEDED)

 /* AUTOGENERATED MOCKS START */
 /* Generated stub for fromwire_channel_announcement */
-bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
+bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *node_signature_1 UNNEEDED, secp256k1_ecdsa_signature *node_signature_2 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_1 UNNEEDED, secp256k1_ecdsa_signature *bitcoin_signature_2 UNNEEDED, u8 **features UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *node_id_1 UNNEEDED, struct pubkey *node_id_2 UNNEEDED, struct pubkey *bitcoin_key_1 UNNEEDED, struct pubkey *bitcoin_key_2 UNNEEDED)
 { fprintf(stderr, "fromwire_channel_announcement called!\n"); abort(); }
 /* Generated stub for fromwire_channel_update */
-bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct sha256_double *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
+bool fromwire_channel_update(const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u16 *flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
 /* Generated stub for fromwire_node_announcement */
 bool fromwire_node_announcement(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, size_t *plen UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, u8 **features UNNEEDED, u32 *timestamp UNNEEDED, struct pubkey *node_id UNNEEDED, u8 rgb_color[3] UNNEEDED, u8 alias[32] UNNEEDED, u8 **addresses UNNEEDED)
@@ -67,7 +67,7 @@ static struct node_connection *add_connection(struct routing_state *rstate,

 int main(void)
 {
-	static const struct sha256_double zerohash;
+	static const struct bitcoin_blkid zerohash;
 	const tal_t *ctx = trc = tal_tmpctx(NULL);
 	struct node_connection *nc;
 	struct routing_state *rstate;
--- a/hsmd/hsm.c
+++ b/hsmd/hsm.c
@@ -196,7 +196,7 @@ static struct io_plan *handle_channel_update_sig(struct io_conn *conn,
 	u32 timestamp, fee_base_msat, fee_proportional_mill;
 	u64 htlc_minimum_msat;
 	u16 flags, cltv_expiry_delta;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	u8 *cu;

 	if (!fromwire_hsm_cupdate_sig_req(tmpctx, dc->msg_in, NULL, &cu)) {
--- a/lightningd/bitcoind.c
+++ b/lightningd/bitcoind.c
@@ -360,9 +360,9 @@ static void process_chaintips(struct bitcoin_cli *bcli)
 	const jsmntok_t *tokens, *t, *end;
 	bool valid;
 	size_t i;
-	struct sha256_double tip;
+	struct bitcoin_blkid tip;
 	void (*cb)(struct bitcoind *bitcoind,
-		   struct sha256_double *tipid,
+		   struct bitcoin_blkid *tipid,
 		   void *arg) = bcli->cb;

 	tokens = json_parse_input(bcli->output, bcli->output_bytes, &valid);
@@ -418,7 +418,7 @@ static void process_chaintips(struct bitcoin_cli *bcli)

 void bitcoind_get_chaintip_(struct bitcoind *bitcoind,
 			    void (*cb)(struct bitcoind *bitcoind,
-				       const struct sha256_double *tipid,
+				       const struct bitcoin_blkid *tipid,
 				       void *arg),
 			    void *arg)
 {
@@ -444,7 +444,7 @@ static void process_rawblock(struct bitcoin_cli *bcli)
 }

 void bitcoind_getrawblock_(struct bitcoind *bitcoind,
-			   const struct sha256_double *blockid,
+			   const struct bitcoin_blkid *blockid,
 			   void (*cb)(struct bitcoind *bitcoind,
 				      struct bitcoin_block *blk,
 				      void *arg),
@@ -486,9 +486,9 @@ void bitcoind_getblockcount_(struct bitcoind *bitcoind,

 static void process_getblockhash(struct bitcoin_cli *bcli)
 {
-	struct sha256_double blkid;
+	struct bitcoin_blkid blkid;
 	void (*cb)(struct bitcoind *bitcoind,
-		   const struct sha256_double *blkid,
+		   const struct bitcoin_blkid *blkid,
 		   void *arg) = bcli->cb;

 	if (bcli->output_bytes == 0
@@ -504,7 +504,7 @@ static void process_getblockhash(struct bitcoin_cli *bcli)
 void bitcoind_getblockhash_(struct bitcoind *bitcoind,
 			    u32 height,
 			    void (*cb)(struct bitcoind *bitcoind,
-				       const struct sha256_double *blkid,
+				       const struct bitcoin_blkid *blkid,
 				       void *arg),
 			    void *arg)
 {
--- a/lightningd/bitcoind.h
+++ b/lightningd/bitcoind.h
@@ -9,7 +9,7 @@
 #include <ccan/typesafe_cb/typesafe_cb.h>
 #include <stdbool.h>

-struct sha256_double;
+struct bitcoin_blkid;
 struct lightningd;
 struct ripemd160;
 struct bitcoin_tx;
@@ -86,7 +86,7 @@ void bitcoind_sendrawtx_(struct bitcoind *bitcoind,

 void bitcoind_get_chaintip_(struct bitcoind *bitcoind,
 			    void (*cb)(struct bitcoind *bitcoind,
-				       const struct sha256_double *tipid,
+				       const struct bitcoin_blkid *tipid,
 				       void *arg),
 			    void *arg);

@@ -95,7 +95,7 @@ void bitcoind_get_chaintip_(struct bitcoind *bitcoind,
 			       typesafe_cb_preargs(void, void *,	\
 						   (cb), (arg),		\
 						   struct bitcoind *,	\
-						   const struct sha256_double *), \
+						   const struct bitcoin_blkid *), \
 			       (arg))

 void bitcoind_getblockcount_(struct bitcoind *bitcoind,
@@ -115,7 +115,7 @@ void bitcoind_getblockcount_(struct bitcoind *bitcoind,
 void bitcoind_getblockhash_(struct bitcoind *bitcoind,
 			    u32 height,
 			    void (*cb)(struct bitcoind *bitcoind,
-				       const struct sha256_double *blkid,
+				       const struct bitcoin_blkid *blkid,
 				       void *arg),
 			    void *arg);
 #define bitcoind_getblockhash(bitcoind_, height, cb, arg)		\
@@ -124,11 +124,11 @@ void bitcoind_getblockhash_(struct bitcoind *bitcoind,
 			       typesafe_cb_preargs(void, void *,	\
 						   (cb), (arg),		\
 						   struct bitcoind *,	\
-						   const struct sha256_double *), \
+						   const struct bitcoin_blkid *), \
 			       (arg))

 void bitcoind_getrawblock_(struct bitcoind *bitcoind,
-			   const struct sha256_double *blockid,
+			   const struct bitcoin_blkid *blockid,
 			   void (*cb)(struct bitcoind *bitcoind,
 				      struct bitcoin_block *blk,
 				      void *arg),
--- a/lightningd/chaintopology.c
+++ b/lightningd/chaintopology.c
@@ -381,9 +381,9 @@ static struct block *new_block(struct chain_topology *topo,
 {
 	struct block *b = tal(topo, struct block);

-	sha256_double(&b->blkid, &blk->hdr, sizeof(blk->hdr));
+	sha256_double(&b->blkid.shad, &blk->hdr, sizeof(blk->hdr));
 	log_debug(topo->log, "Adding block %s",
-		  type_to_string(ltmp, struct sha256_double, &b->blkid));
+		  type_to_string(ltmp, struct bitcoin_blkid, &b->blkid));
 	assert(!block_map_get(&topo->block_map, &b->blkid));
 	b->next = next;
 	b->topo = topo;
@@ -443,7 +443,7 @@ static void rawblock_tip(struct bitcoind *bitcoind,
 }

 static void check_chaintip(struct bitcoind *bitcoind,
-			   const struct sha256_double *tipid,
+			   const struct bitcoin_blkid *tipid,
 			   struct chain_topology *topo)
 {
 	/* 0 is the main tip. */
@@ -478,7 +478,7 @@ static void init_topo(struct bitcoind *bitcoind,
 }

 static void get_init_block(struct bitcoind *bitcoind,
-			   const struct sha256_double *blkid,
+			   const struct bitcoin_blkid *blkid,
 			   struct chain_topology *topo)
 {
 	bitcoind_getrawblock(bitcoind, blkid, init_topo, topo);
--- a/lightningd/chaintopology.h
+++ b/lightningd/chaintopology.h
@@ -16,7 +16,6 @@ struct bitcoind;
 struct command;
 struct lightningd;
 struct peer;
-struct sha256_double;
 struct txwatch;

 enum feerate {
@@ -50,7 +49,7 @@ struct block {
 	struct block *next;

 	/* Key for hash table */
-	struct sha256_double blkid;
+	struct bitcoin_blkid blkid;

 	/* Transactions in this block we care about */
 	const struct bitcoin_tx **txs;
@@ -66,12 +65,12 @@ struct block {
 };

 /* Hash blocks by sha */
-static inline const struct sha256_double *keyof_block_map(const struct block *b)
+static inline const struct bitcoin_blkid *keyof_block_map(const struct block *b)
 {
 	return &b->blkid;
 }

-static inline size_t hash_sha(const struct sha256_double *key)
+static inline size_t hash_sha(const struct bitcoin_blkid *key)
 {
 	size_t ret;

@@ -79,7 +78,7 @@ static inline size_t hash_sha(const struct sha256_double *key)
 	return ret;
 }

-static inline bool block_eq(const struct block *b, const struct sha256_double *key)
+static inline bool block_eq(const struct block *b, const struct bitcoin_blkid *key)
 {
 	return structeq(&b->blkid, key);
 }
--- a/lightningd/peer_control.c
+++ b/lightningd/peer_control.c
@@ -461,12 +461,12 @@ static bool extract_channel_id(const u8 *in_pkt, struct channel_id *channel_id)
 	u16 ignored_u16;
 	u8 ignored_u8;
 	struct pubkey ignored_pubkey;
-	struct sha256_double ignored_shadouble;
+	struct bitcoin_blkid ignored_chainhash;

 	if (fromwire_channel_reestablish(in_pkt, NULL, channel_id,
 					 &ignored_u64, &ignored_u64))
 		return true;
-	if (fromwire_open_channel(in_pkt, NULL, &ignored_shadouble,
+	if (fromwire_open_channel(in_pkt, NULL, &ignored_chainhash,
 				  channel_id, &ignored_u64,
 				  &ignored_u64, &ignored_u64,
 				  &ignored_u64, &ignored_u64,
--- a/openingd/opening.c
+++ b/openingd/opening.c
@@ -529,7 +529,7 @@ static u8 *fundee_channel(struct state *state,
 	struct pubkey their_funding_pubkey;
 	secp256k1_ecdsa_signature theirsig, sig;
 	struct bitcoin_tx *their_commit, *our_commit;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	u8 *msg;
 	const u8 *wscript;
 	u8 channel_flags;
@@ -574,7 +574,7 @@ static u8 *fundee_channel(struct state *state,
 		negotiation_failed(state, true,
 				   "Unknown chain-hash %s",
 				   type_to_string(peer_msg,
-						  struct sha256_double,
+						  struct bitcoin_blkid,
 						  &chain_hash));
 	}

--- a/tools/generate-wire.py
+++ b/tools/generate-wire.py
@@ -18,7 +18,7 @@ type2size = {
    'struct preimage': 32,
    'struct pubkey': 33,
    'struct sha256': 32,
-    'struct sha256_double': 32,
+    'struct bitcoin_blkid': 32,
    'struct bitcoin_txid': 32,
    'u64': 8,
    'u32': 4,
@@ -78,7 +78,7 @@ partialtypemap = {
    'signature': FieldType('secp256k1_ecdsa_signature'),
    'features': FieldType('u8'),
    'channel_id': FieldType('struct channel_id'),
-    'chain_hash': FieldType('struct sha256_double'),
+    'chain_hash': FieldType('struct bitcoin_blkid'),
    'funding_txid': FieldType('struct bitcoin_txid'),
    'pad': FieldType('pad'),
 }
--- a/wire/fromwire.c
+++ b/wire/fromwire.c
@@ -183,6 +183,12 @@ void fromwire_bitcoin_txid(const u8 **cursor, size_t *max,
 	fromwire_sha256_double(cursor, max, &txid->shad);
 }

+void fromwire_bitcoin_blkid(const u8 **cursor, size_t *max,
+			    struct bitcoin_blkid *blkid)
+{
+	fromwire_sha256_double(cursor, max, &blkid->shad);
+}
+
 void fromwire_preimage(const u8 **cursor, size_t *max, struct preimage *preimage)
 {
 	fromwire(cursor, max, preimage, sizeof(*preimage));
--- a/wire/test/run-peer-wire.c
+++ b/wire/test/run-peer-wire.c
@@ -128,7 +128,7 @@ struct msg_channel_update {
 	u64 htlc_minimum_msat;
 	u32 fee_base_msat;
 	u32 fee_proportional_millionths;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct short_channel_id short_channel_id;
 };
 struct msg_funding_locked {
@@ -156,7 +156,7 @@ struct msg_node_announcement {
 	u8 *addresses;
 };
 struct msg_open_channel {
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct channel_id temporary_channel_id;
 	u64 funding_satoshis;
 	u64 push_msat;
@@ -186,7 +186,7 @@ struct msg_channel_announcement {
 	secp256k1_ecdsa_signature bitcoin_signature_1;
 	secp256k1_ecdsa_signature bitcoin_signature_2;
 	u8 *features;
-	struct sha256_double chain_hash;
+	struct bitcoin_blkid chain_hash;
 	struct short_channel_id short_channel_id;
 	struct pubkey node_id_1;
 	struct pubkey node_id_2;
--- a/wire/towire.c
+++ b/wire/towire.c
@@ -125,6 +125,11 @@ void towire_bitcoin_txid(u8 **pptr, const struct bitcoin_txid *txid)
 	towire_sha256_double(pptr, &txid->shad);
 }

+void towire_bitcoin_blkid(u8 **pptr, const struct bitcoin_blkid *blkid)
+{
+	towire_sha256_double(pptr, &blkid->shad);
+}
+
 void towire_preimage(u8 **pptr, const struct preimage *preimage)
 {
 	towire(pptr, preimage, sizeof(*preimage));
--- a/wire/wire.h
+++ b/wire/wire.h
@@ -1,6 +1,7 @@
 #ifndef LIGHTNING_WIRE_WIRE_H
 #define LIGHTNING_WIRE_WIRE_H
 #include "config.h"
+#include <bitcoin/block.h>
 #include <bitcoin/privkey.h>
 #include <bitcoin/pubkey.h>
 #include <bitcoin/shadouble.h>
@@ -15,6 +16,7 @@ struct channel_id {
 	u8 id[32];
 };

+struct bitcoin_blkid;
 struct bitcoin_txid;
 struct preimage;
 struct ripemd160;
@@ -40,6 +42,7 @@ void towire_short_channel_id(u8 **pptr,
 void towire_sha256(u8 **pptr, const struct sha256 *sha256);
 void towire_sha256_double(u8 **pptr, const struct sha256_double *sha256d);
 void towire_bitcoin_txid(u8 **pptr, const struct bitcoin_txid *txid);
+void towire_bitcoin_blkid(u8 **pptr, const struct bitcoin_blkid *blkid);
 void towire_preimage(u8 **pptr, const struct preimage *preimage);
 void towire_ripemd160(u8 **pptr, const struct ripemd160 *ripemd);
 void towire_u8(u8 **pptr, u8 v);
@@ -74,6 +77,8 @@ void fromwire_sha256_double(const u8 **cursor, size_t *max,
 			    struct sha256_double *sha256d);
 void fromwire_bitcoin_txid(const u8 **cursor, size_t *max,
 			   struct bitcoin_txid *txid);
+void fromwire_bitcoin_blkid(const u8 **cursor, size_t *max,
+			   struct bitcoin_blkid *blkid);
 void fromwire_preimage(const u8 **cursor, size_t *max, struct preimage *preimage);
 void fromwire_ripemd160(const u8 **cursor, size_t *max, struct ripemd160 *ripemd);
 void fromwire_pad(const u8 **cursor, size_t *max, size_t num);