plugins/multifundchannel.c: Implementation of `multifundchannel`.

Changelog-Added: We now have `multifundchannel` as a builtin plugin command to fund multiple channels to different peers all in a single onchain transaction.


Header from folded patch 'fixup-use-json_add_psbt.patch':

fixup!


Header from folded patch 'use-goto-no-ok-chain.patch':

fixup!


Header from folded patch 'destinations-at-parse-time.patch':

fixup!


Header from folded patch 'multifundchannel__use_jsmntoks_to_pass_through_json_string,_not_strings.patch':

multifundchannel: use jsmntoks to pass through json string, not strings

Passing in "" for utxos would crash lightningd on the command-line
otherwise. Now returns an error.


Header from folded patch 'update_plugins-multifundchannel.c.patch':

Update plugins/multifundchannel.c

Co-authored-by: Darosior <darosior@protonmail.com>

.github/CODEOWNERS

@@ -8,6 +8,7 @@ wallet/                 @cdecker
 *.py                    @cdecker
 
 wallet/invoices.*       @ZmnSCPxj
+plugins/multifundchannel.c @ZmnSCPxj
 
 common/param.*          @wythe
 common/json.*           @wythe

bitcoin/psbt.h

@@ -17,6 +17,16 @@ struct bitcoin_signature;
 struct bitcoin_txid;
 struct pubkey;
 
+/** psbt_destroy - Destroy a PSBT that is not tal-allocated
+ *
+ * @psbt - the PSBT to destroy
+ *
+ * WARNING Do NOT call this function directly if you got the
+ * PSBT from create_psbt, new_psbt, psbt_from_bytes,
+ * psbt_from_b64, or fromwire_wally_psbt.
+ * Those functions register this function as a `tal_destructor`
+ * automatically.
+ */
 void psbt_destroy(struct wally_psbt *psbt);
 
 /**

plugins/.gitignore

@@ -2,3 +2,4 @@ autoclean
 bcli
 fundchannel
 pay
+multifundchannel

plugins/Makefile

@@ -24,6 +24,9 @@ PLUGIN_PAY_LIB_SRC := plugins/libplugin-pay.c
 PLUGIN_PAY_LIB_HEADER := plugins/libplugin-pay.h
 PLUGIN_PAY_LIB_OBJS := $(PLUGIN_PAY_LIB_SRC:.c=.o)
 
+PLUGIN_MULTIFUNDCHANNEL_SRC := plugins/multifundchannel.c
+PLUGIN_MULTIFUNDCHANNEL_OBJS := $(PLUGIN_MULTIFUNDCHANNEL_SRC:.c=.o)
+
 PLUGIN_ALL_SRC :=				\
 	$(PLUGIN_AUTOCLEAN_SRC)			\
 	$(PLUGIN_BCLI_SRC)			\
@@ -31,6 +34,7 @@ PLUGIN_ALL_SRC :=				\
 	$(PLUGIN_KEYSEND_SRC)			\
 	$(PLUGIN_TXPREPARE_SRC)			\
 	$(PLUGIN_LIB_SRC)			\
+	$(PLUGIN_MULTIFUNDCHANNEL_SRC)		\
 	$(PLUGIN_PAY_LIB_SRC)			\
 	$(PLUGIN_PAY_SRC)
 PLUGIN_ALL_HEADER :=				\
@@ -44,6 +48,7 @@ PLUGINS :=					\
 	plugins/fundchannel			\
 	plugins/keysend				\
 	plugins/pay				\
+	plugins/multifundchannel		\
 	plugins/txprepare
 
 # Make sure these depend on everything.
@@ -105,4 +110,6 @@ plugins/bcli: bitcoin/chainparams.o $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS) $(PLU
 plugins/keysend: bitcoin/chainparams.o wire/tlvstream.o wire/onion$(EXP)_wiregen.o $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) $(CCAN_OBJS)
 $(PLUGIN_KEYSEND_OBJS): $(PLUGIN_PAY_LIB_HEADER)
 
+plugins/multifundchannel: bitcoin/chainparams.o common/addr.o $(PLUGIN_MULTIFUNDCHANNEL_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) $(CCAN_OBJS)
+
 $(PLUGIN_ALL_OBJS): $(PLUGIN_LIB_HEADER)