bitcoind: getrawblock helper.

It turns out using the verbose=false parameter, you can get the raw block
from getblock.  Do that.

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

Makefile

@@ -22,6 +22,7 @@ TEST_PROGRAMS :=				\
 
 BITCOIN_SRC :=					\
 	bitcoin/base58.c			\
+	bitcoin/block.c			\
 	bitcoin/locktime.c			\
 	bitcoin/pubkey.c			\
 	bitcoin/script.c			\
@@ -129,6 +130,7 @@ CCAN_HEADERS :=						\
 
 BITCOIN_HEADERS := bitcoin/address.h		\
 	bitcoin/base58.h			\
+	bitcoin/block.h				\
 	bitcoin/locktime.h			\
 	bitcoin/privkey.h			\
 	bitcoin/pubkey.h			\

bitcoin/block.c

@@ -0,0 +1,38 @@
+#include "bitcoin/block.h"
+#include "bitcoin/tx.h"
+#include <ccan/str/hex/hex.h>
+
+/* Encoding is <blockhdr> <varint-num-txs> <tx>... */
+struct bitcoin_block *bitcoin_block_from_hex(const tal_t *ctx,
+					     const char *hex, size_t hexlen)
+{
+	struct bitcoin_block *b;
+	u8 *linear_tx;
+	const u8 *p;
+	size_t len, i, num;
+
+	if (hexlen && hex[hexlen-1] == '\n')
+		hexlen--;
+
+	/* Set up the block for success. */
+	b = tal(ctx, struct bitcoin_block);
+
+	/* De-hex the array. */
+	len = hex_data_size(hexlen);
+	p = linear_tx = tal_arr(ctx, u8, len);
+	if (!hex_decode(hex, hexlen, linear_tx, len))
+		return tal_free(b);
+
+	pull(&p, &len, &b->hdr, sizeof(b->hdr));
+	num = pull_varint(&p, &len);
+	b->tx = tal_arr(b, struct bitcoin_tx *, num);
+	for (i = 0; i < num; i++)
+		b->tx[i] = pull_bitcoin_tx(b->tx, &p, &len);
+
+	/* We should end up not overrunning, nor have extra */
+	if (!p || len)
+		return tal_free(b);
+
+	tal_free(linear_tx);
+	return b;
+}

bitcoin/block.h

@@ -0,0 +1,28 @@
+#ifndef LIGHTNING_BITCOIN_BLOCK_H
+#define LIGHTNING_BITCOIN_BLOCK_H
+#include "config.h"
+#include "bitcoin/shadouble.h"
+#include <ccan/endian/endian.h>
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+#include <stdbool.h>
+
+struct bitcoin_block_hdr {
+	le32 version;
+	struct sha256_double prev_hash;
+	struct sha256_double merkle_hash;
+	le32 timestamp;
+	le32 target;
+	le32 nonce;
+};
+
+struct bitcoin_block {
+	struct bitcoin_block_hdr hdr;
+	/* tal_count shows now many */
+	struct bitcoin_tx **tx;
+};
+
+struct bitcoin_block *bitcoin_block_from_hex(const tal_t *ctx,
+					     const char *hex, size_t hexlen);
+
+#endif /* LIGHTNING_BITCOIN_BLOCK_H */

bitcoin/tx.c

@@ -1,3 +1,4 @@
+#include "bitcoin/block.h"
 #include "tx.h"
 #include <assert.h>
 #include <ccan/cast/cast.h>
@@ -343,7 +344,7 @@ struct bitcoin_tx *bitcoin_tx(const tal_t *ctx, varint_t input_count,
 }
 
 /* Sets *cursor to NULL and returns NULL when a pull fails. */
-static const u8 *pull(const u8 **cursor, size_t *max, void *copy, size_t n)
+const u8 *pull(const u8 **cursor, size_t *max, void *copy, size_t n)
 {
 	const u8 *p = *cursor;
 
@@ -362,7 +363,7 @@ static const u8 *pull(const u8 **cursor, size_t *max, void *copy, size_t n)
 	return memcheck(p, n);
 }
 
-static u64 pull_varint(const u8 **cursor, size_t *max)
+u64 pull_varint(const u8 **cursor, size_t *max)
 {
 	u64 ret;
 	size_t len;
@@ -470,8 +471,8 @@ static void pull_witness(struct bitcoin_tx_input *inputs, size_t i,
 	}
 }
 
-static struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx,
-					  const u8 **cursor, size_t *max)
+struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx,
+				   const u8 **cursor, size_t *max)
 {
 	struct bitcoin_tx *tx = tal(ctx, struct bitcoin_tx);
 	size_t i;
@@ -505,8 +506,8 @@ static struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx,
 	}
 	tx->lock_time = pull_le32(cursor, max);
 
-	/* If we ran short, or have bytes left over, fail. */
-	if (!*cursor || *max != 0)
+	/* If we ran short, fail. */
+	if (!*cursor)
 		tx = tal_free(tx);
 	return tx;
 }
@@ -533,6 +534,9 @@ struct bitcoin_tx *bitcoin_tx_from_hex(const tal_t *ctx, const char *hex,
 	if (!tx)
 		goto fail;
 
+	if (len)
+		goto fail_free_tx;
+	
 	if (end != hex + hexlen && *end != '\n')
 		goto fail_free_tx;
 

bitcoin/tx.h

@@ -73,4 +73,11 @@ bool bitcoin_txid_from_hex(const char *hexstr, size_t hexstr_len,
 bool bitcoin_txid_to_hex(const struct sha256_double *txid,
 			 char *hexstr, size_t hexstr_len);
 
+
+/* Internal de-linearization functions. */
+struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx,
+				   const u8 **cursor, size_t *max);
+u64 pull_varint(const u8 **cursor, size_t *max);
+const u8 *pull(const u8 **cursor, size_t *max, void *copy, size_t n);
+
 #endif /* LIGHTNING_BITCOIN_TX_H */

daemon/bitcoind.c

@@ -1,5 +1,6 @@
 /* Code for talking to bitcoind.  We use bitcoin-cli. */
 #include "bitcoin/base58.h"
+#include "bitcoin/block.h"
 #include "bitcoin/shadouble.h"
 #include "bitcoin/tx.h"
 #include "bitcoind.h"
@@ -724,6 +725,40 @@ void bitcoind_getblock_(struct lightningd_state *dstate,
 			  "getblock", hex, NULL);
 }
 
+static void process_rawblock(struct bitcoin_cli *bcli)
+{
+	struct bitcoin_block *blk;
+	void (*cb)(struct lightningd_state *dstate,
+		   struct bitcoin_block *blk,
+		   void *arg) = bcli->cb;
+
+	/* FIXME: Just get header if we can't get full block. */
+	if (!bcli->output)
+		fatal("%s: unknown block?", bcli_args(bcli));
+
+	blk = bitcoin_block_from_hex(bcli, bcli->output, bcli->output_bytes);
+	if (!blk)
+		fatal("%s: bad block '%.*s'?",
+		      bcli_args(bcli),
+		      (int)bcli->output_bytes, (char *)bcli->output);
+
+	cb(bcli->dstate, blk, bcli->cb_arg);
+}
+
+void bitcoind_getrawblock_(struct lightningd_state *dstate,
+			   const struct sha256_double *blockid,
+			   void (*cb)(struct lightningd_state *dstate,
+				      struct bitcoin_block *blk,
+				      void *arg),
+			   void *arg)
+{
+	char hex[hex_str_size(sizeof(*blockid))];
+
+	hex_encode(blockid, sizeof(*blockid), hex, sizeof(hex));
+	start_bitcoin_cli(dstate, process_rawblock, cb, arg,
+			  "getblock", hex, "false", NULL);
+}
+
 static void process_getblockcount(struct bitcoin_cli *bcli)
 {
 	u32 blockcount;

daemon/bitcoind.h

@@ -10,6 +10,7 @@ struct lightningd_state;
 struct ripemd160;
 struct bitcoin_tx;
 struct peer;
+struct bitcoin_block;
 /* -datadir arg for bitcoin-cli. */
 extern char *bitcoin_datadir;
 
@@ -121,6 +122,20 @@ void bitcoind_getblockhash_(struct lightningd_state *dstate,
 						   const struct sha256_double *), \
 			       (arg))
 
+void bitcoind_getrawblock_(struct lightningd_state *dstate,
+			   const struct sha256_double *blockid,
+			   void (*cb)(struct lightningd_state *dstate,
+				      struct bitcoin_block *blk,
+				      void *arg),
+			   void *arg);
+#define bitcoind_getrawblock(dstate, blkid, cb, arg)			\
+	bitcoind_getrawblock_((dstate), (blkid),			\
+			      typesafe_cb_preargs(void, void *,		\
+						  (cb), (arg),		\
+						  struct lightningd_state *, \
+						  struct bitcoin_block *), \
+			      (arg))
+
 void normalized_txid(const struct bitcoin_tx *tx, struct sha256_double *txid);
 
 void check_bitcoind_config(struct lightningd_state *dstate);