Removed redundancies in withdraw and fundchannel.

No new functionality, just a continuation of my work toward completing ElementsProject#665.

I removed the common members of `struct withdrawal` and `struct fund_channel`
and placed them in a new `struct wallet_tx`.  Then it was fairly straightforward
to reimplement the existing code in terms of `wallet_tx`.

Since I made some structural changes I wanted to get this approved before I
go any farther.

Added 'all' to fundchannel help message.

common/Makefile

@@ -42,6 +42,7 @@ COMMON_SRC_NOGEN :=				\
 	common/utils.c				\
 	common/utxo.c				\
 	common/version.c			\
+	common/wallet_tx.c			\
 	common/wireaddr.c			\
 	common/wire_error.c			\
 	common/withdraw_tx.c

common/wallet_tx.c

@@ -0,0 +1,49 @@
+#include <common/wallet_tx.h>
+#include <inttypes.h>
+#include <lightningd/jsonrpc_errors.h>
+#include <wallet/wallet.h>
+
+void wtx_init(struct command *cmd, struct wallet_tx * wtx)
+{
+	wtx->cmd = cmd;
+	wtx->amount = 0;
+	wtx->change_key_index = 0;
+	wtx->utxos = NULL;
+	wtx->all_funds = false;
+	wtx->desttok = NULL;
+}
+
+bool wtx_select_utxos(struct wallet_tx * tx, u32 fee_rate_per_kw,
+	              size_t out_len)
+{
+	u64 fee_estimate;
+	if (tx->all_funds) {
+		tx->utxos = wallet_select_all(tx->cmd, tx->cmd->ld->wallet,
+					      fee_rate_per_kw, out_len,
+					      &tx->amount,
+					      &fee_estimate);
+		if (!tx->utxos || tx->amount < 546) {
+			command_fail(tx->cmd, "Cannot afford fee %"PRIu64,
+				     fee_estimate);
+			return false;
+		}
+		tx->change = 0;
+	} else {
+		tx->utxos = wallet_select_coins(tx->cmd, tx->cmd->ld->wallet,
+						tx->amount,
+						fee_rate_per_kw, out_len,
+						&fee_estimate, &tx->change);
+		if (!tx->utxos || tx->amount < 546) {
+			command_fail(tx->cmd,
+			"Cannot afford funding transaction");
+			return false;
+		}
+		if (tx->change < 546) {
+			tx->change = 0;
+			tx->change_key_index = 0;
+		} else {
+			tx->change_key_index = wallet_get_newindex(tx->cmd->ld);
+		}
+	}
+	return true;
+}

common/wallet_tx.h

@@ -0,0 +1,27 @@
+#ifndef LIGHTNING_COMMON_WALLET_TX_H
+#define LIGHTNING_COMMON_WALLET_TX_H
+#include "config.h"
+#include <ccan/short_types/short_types.h>
+#include <lightningd/json.h>
+#include <lightningd/jsonrpc.h>
+#include <lightningd/lightningd.h>
+
+/* A specification of funds in the wallet used for funding channels and
+ * withdrawal.
+ */
+struct wallet_tx {
+	struct command *cmd;
+	u64 amount;
+	u64 change;
+	u32 change_key_index;
+	const struct utxo **utxos;
+
+	bool all_funds;
+	const jsmntok_t *desttok;
+	const jsmntok_t *sattok;
+};
+
+void wtx_init(struct command *cmd, struct wallet_tx *wtx);
+bool wtx_select_utxos(struct wallet_tx * tx, u32 fee_rate_per_kw,
+		      size_t out_len);
+#endif /* LIGHTNING_COMMON_WALLET_TX_H */

lightningd/Makefile

@@ -44,13 +44,13 @@ LIGHTNINGD_COMMON_OBJS :=			\
 	common/utils.o				\
 	common/utxo.o				\
 	common/version.o			\
+	common/wallet_tx.o			\
 	common/wire_error.o			\
 	common/wireaddr.o			\
 	common/withdraw_tx.o
 
 LIGHTNINGD_SRC :=				\
 	lightningd/bitcoind.c			\
-	lightningd/build_utxos.c		\
 	lightningd/chaintopology.c		\
 	lightningd/channel.c			\
 	lightningd/channel_control.c		\

lightningd/jsonrpc.c

@@ -13,6 +13,7 @@
 #include <common/json_escaped.h>
 #include <common/memleak.h>
 #include <common/version.h>
+#include <common/wallet_tx.h>
 #include <common/wireaddr.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -852,3 +853,14 @@ json_tok_address_scriptpubkey(const tal_t *cxt,
 
 	return ADDRESS_PARSE_UNRECOGNIZED;
 }
+
+bool json_tok_wtx(struct wallet_tx * tx, const char * buffer)
+{
+	if (json_tok_streq(buffer, tx->sattok, "all")) {
+		tx->all_funds = true;
+	} else if (!json_tok_u64(buffer, tx->sattok, &tx->amount)) {
+		command_fail(tx->cmd, "Invalid satoshis");
+		return false;
+	}
+	return true;
+}

lightningd/jsonrpc.h

@@ -8,6 +8,7 @@
 
 struct bitcoin_txid;
 struct wireaddr;
+struct wallet_tx;
 
 /* Context for a command (from JSON, but might outlive the connection!)
  * You can allocate off this for temporary objects. */
@@ -101,5 +102,8 @@ json_tok_address_scriptpubkey(const tal_t *ctx,
 			      const char *buffer,
 			      const jsmntok_t *tok, const u8 **scriptpubkey);
 
+/* Parse the satoshi token in wallet_tx. */
+bool json_tok_wtx(struct wallet_tx * tx, const char * buffer);
+
 AUTODATA_TYPE(json_command, struct json_command);
 #endif /* LIGHTNING_LIGHTNINGD_JSONRPC_H */