dev: add option flag for specifying temporary channel id

--dev-force-tmp-channel-id flag takes a 64-character hex string
to use as the temporary channel id. Useful for spec tests

[ Fixed crash in non-DEVELOPER mode --RR ]
Changelog-None

lightningd/lightningd.c

@@ -126,6 +126,7 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	ld->dev_force_bip32_seed = NULL;
 	ld->dev_force_channel_secrets = NULL;
 	ld->dev_force_channel_secrets_shaseed = NULL;
+	ld->dev_force_tmp_channel_id = NULL;
 #endif
 
 	/*~ These are CCAN lists: an embedded double-linked list.  It's not

lightningd/lightningd.h

@@ -223,6 +223,8 @@ struct lightningd {
 	/* These are the forced channel secrets for the node. */
 	struct secrets *dev_force_channel_secrets;
 	struct sha256 *dev_force_channel_secrets_shaseed;
+
+	struct channel_id *dev_force_tmp_channel_id;
 #endif /* DEVELOPER */
 
 	/* tor support */

lightningd/opening_control.c

@@ -965,6 +965,7 @@ void peer_start_openingd(struct peer *peer,
 				  feature_negotiated(peer->features,
 						     OPT_STATIC_REMOTEKEY),
 				  send_msg,
+				  IFDEV(peer->ld->dev_force_tmp_channel_id, NULL),
 				  IFDEV(peer->ld->dev_fast_gossip, false));
 	subd_send_msg(uc->openingd, take(msg));
 }

lightningd/options.c

@@ -449,6 +449,17 @@ static char *opt_force_bip32_seed(const char *optarg, struct lightningd *ld)
 	return NULL;
 }
 
+static char *opt_force_tmp_channel_id(const char *optarg, struct lightningd *ld)
+{
+	tal_free(ld->dev_force_tmp_channel_id);
+	ld->dev_force_tmp_channel_id = tal(ld, struct channel_id);
+	if (!hex_decode(optarg, strlen(optarg),
+			ld->dev_force_tmp_channel_id,
+			sizeof(*ld->dev_force_tmp_channel_id)))
+		return tal_fmt(NULL, "Unable to parse channel id '%s'", optarg);
+	return NULL;
+}
+
 static char *opt_force_channel_secrets(const char *optarg,
 				       struct lightningd *ld)
 {
@@ -535,6 +546,8 @@ static void dev_register_opts(struct lightningd *ld)
 			 "Maximum number of blocks we wait for a channel "
 			 "funding transaction to confirm, if we are the "
 			 "fundee.");
+	opt_register_arg("--dev-force-tmp-channel-id", opt_force_tmp_channel_id, NULL, ld,
+			 "Force the temporary channel id, instead of random");
 }
 #endif /* DEVELOPER */
 

openingd/opening_wire.csv

@@ -24,6 +24,7 @@ msgdata,opening_init,option_static_remotekey,bool,
 # Optional msg to send.
 msgdata,opening_init,len,u16,
 msgdata,opening_init,msg,u8,len
+msgdata,opening_init,dev_temporary_channel_id,?byte,32
 msgdata,opening_init,dev_fast_gossip,bool,
 
 # Openingd->master: they offered channel, should we continue?

openingd/openingd.c

@@ -15,6 +15,7 @@
 #include <ccan/breakpoint/breakpoint.h>
 #include <ccan/cast/cast.h>
 #include <ccan/fdpass/fdpass.h>
+#include <ccan/mem/mem.h>
 #include <ccan/tal/str/str.h>
 #include <common/crypto_sync.h>
 #include <common/derive_basepoints.h>
@@ -54,6 +55,11 @@
 #define REQ_FD STDIN_FILENO
 #define HSM_FD 6
 
+#if DEVELOPER
+/* If --dev-force-tmp-channel-id is set, it ends up here */
+static struct channel_id *dev_force_tmp_channel_id;
+#endif /* DEVELOPER */
+
 /* Global state structure.  This is only for the one specific peer and channel */
 struct state {
 	struct per_peer_state *pps;
@@ -463,6 +469,11 @@ static bool setup_channel_funder(struct state *state)
 	 * until we know their funding_pubkey) */
 	temporary_channel_id(&state->channel_id);
 
+#if DEVELOPER
+	/* --dev-force-tmp-channel-id specified */
+	if (dev_force_tmp_channel_id)
+		state->channel_id = *dev_force_tmp_channel_id;
+#endif
 	/* BOLT #2:
 	 *
 	 * The sending node:
@@ -1420,6 +1431,7 @@ int main(int argc, char *argv[])
 	struct pollfd pollfd[3];
 	struct state *state = tal(NULL, struct state);
 	struct secret *none;
+	struct channel_id *force_tmp_channel_id;
 
 	subdaemon_setup(argc, argv);
 
@@ -1442,9 +1454,14 @@ int main(int argc, char *argv[])
 				   &state->features,
 				   &state->option_static_remotekey,
 				   &inner,
+				   &force_tmp_channel_id,
 				   &dev_fast_gossip))
 		master_badmsg(WIRE_OPENING_INIT, msg);
 
+#if DEVELOPER
+	dev_force_tmp_channel_id = force_tmp_channel_id;
+#endif
+
 	/* 3 == peer, 4 == gossipd, 5 = gossip_store, 6 = hsmd */
 	per_peer_state_set_fds(state->pps, 3, 4, 5);