lighningd: Add zeroconf primitives

These are used to manage zeroconf related operations, such as managing
options, determining if a peer is trusted to do a zeroconf channel
open, etc.

common/Makefile

@@ -89,7 +89,8 @@ COMMON_SRC_NOGEN :=				\
 	common/version.c			\
 	common/wallet.c				\
 	common/wireaddr.c			\
-	common/wire_error.c
+	common/wire_error.c			\
+	common/zeroconf.c
 
 
 COMMON_SRC_GEN := common/status_wiregen.c common/peer_status_wiregen.c

common/zeroconf.c

@@ -0,0 +1,46 @@
+#include "config.h"
+#include <assert.h>
+#include <common/zeroconf.h>
+#include <wire/wire.h>
+
+
+struct zeroconf_options *zeroconf_options_new(const tal_t *ctx)
+{
+	struct zeroconf_options *z = tal(ctx, struct zeroconf_options);
+	z->allow_all = false;
+	z->allowlist = tal_arr(z, struct node_id, 0);
+	return z;
+}
+
+bool fromwire_zeroconf_options(const u8 **cursor, size_t *max,
+			       struct zeroconf_options *opts)
+{
+	size_t listsize;
+	opts->allow_all = fromwire_bool(cursor, max);
+
+	listsize = fromwire_u16(cursor, max);
+	opts->allowlist = tal_arr(opts, struct node_id, listsize);
+	for (size_t i = 0; i < listsize; i++)
+		fromwire_node_id(cursor, max, &opts->allowlist[i]);
+	return *cursor != NULL;
+}
+void towire_zeroconf_options(u8 **pptr, const struct zeroconf_options *opts)
+{
+	towire_bool(pptr, opts->allow_all);
+	assert(opts->allowlist != NULL);
+	towire_u16(pptr, tal_count(opts->allowlist));
+	for (size_t i = 0; i < tal_count(opts->allowlist); i++)
+		towire_node_id(pptr, &opts->allowlist[i]);
+}
+
+bool zeroconf_allow_peer(const struct zeroconf_options *zopts,
+			 const struct node_id *node_id)
+{
+	if (zopts->allow_all)
+		return true;
+
+	for (size_t i=0; i<tal_count(zopts->allowlist); i++)
+		if (node_id_eq(node_id, &zopts->allowlist[i]))
+			return true;
+	return false;
+}

common/zeroconf.h

@@ -0,0 +1,34 @@
+#ifndef LIGHTNING_COMMON_ZEROCONF_H
+#define LIGHTNING_COMMON_ZEROCONF_H
+#include "config.h"
+#include <common/node_id.h>
+
+/* Helper struct to hand options around various daemons. */
+struct zeroconf_options {
+       bool allow_all;
+       /* List of nodes we allow zeroconf from/to */
+       struct node_id *allowlist;
+};
+
+struct zeroconf_options *zeroconf_options_new(const tal_t *ctx);
+
+bool fromwire_zeroconf_options(const u8 **cursor, size_t *max,
+                              struct zeroconf_options *opts);
+void towire_zeroconf_options(u8 **pptr, const struct zeroconf_options *opts);
+
+/**
+ * Check if a given node should be allowed for zeroconf.
+ *
+ * Determines whether we'd be happy to open or accept a zeroconf
+ * channel with this peers. It is used to selectively apply the
+ * `option_zeroconf` to the `init` message we'll send to the peer when
+ * a connection is established. This is sticky, as in it applies to
+ * all channels we'll open or accept on this connection. Notice that
+ * this does not differentiate between opening of accepting a channel,
+ * and that's because the accepter doesn't get a say in the channel
+ * negotiation.
+ */
+bool zeroconf_allow_peer(const struct zeroconf_options *zopts,
+			 const struct node_id *node_id);
+
+#endif /* LIGHTNING_COMMON_ZEROCONF_H */

lightningd/opening_common.c

@@ -167,10 +167,3 @@ void channel_config(struct lightningd *ld,
 	 /* This is filled in by lightning_openingd, for consistency. */
 	 ours->channel_reserve = AMOUNT_SAT(UINT64_MAX);
 }
-
-bool opening_zeroconf_allow(struct lightningd *ld, struct node_id *peer)
-{
-	/* FIXME: Actually read the options from `ld` and return
-	 * `true` if we were configured to do so. */
-	return true;
-}

lightningd/opening_common.h

@@ -127,18 +127,4 @@ void channel_config(struct lightningd *ld,
 		    u32 *max_to_self_delay,
 		    struct amount_msat *min_effective_htlc_capacity);
 
-/**
- * Are we ok with this peer opening a zeroconf channel?
- *
- * Determines whether we'd be happy to open or accept a zeroconf
- * channel with this peers. It is used to selectively apply the
- * `option_zeroconf` to the `init` message we'll send to the peer when
- * a connection is established. This is sticky, as in it applies to
- * all channels we'll open or accept on this connection. Notice that
- * this does not differentiate between opening of accepting a channel,
- * and that's because the accepter doesn't get a say in the channel
- * negotiation.
- */
-bool opening_zeroconf_allow(struct lightningd *ld, struct node_id *peer);
-
 #endif /* LIGHTNING_LIGHTNINGD_OPENING_COMMON_H */

lightningd/opening_control.c

@@ -897,14 +897,17 @@ bool peer_start_openingd(struct peer *peer, struct peer_fd *peer_fd)
 	 *     reasonable to avoid double-spending of the funding transaction.
 	 */
 	uc->minimum_depth = peer->ld->config.anchor_confirms;
-#ifdef EXPERIMENTAL_FEATURES /* zeroconf */
-	if (opening_zeroconf_allow(peer->ld, &peer->id)) {
+	if (zeroconf_allow_peer(peer->ld->config.zeroconf, &peer->id)) {
 		uc->minimum_depth = 0;
+	} else {
+		/* Unset the bit for ZEROCONF, since we don't want to signal
+		 * support and then reject when they try to use it. */
+		featurebits_unset(&uc->our_features->bits[INIT_FEATURE], OPT_ZEROCONF);
 	}
 
 	msg = towire_openingd_init(NULL,
 				  chainparams,
-				  peer->ld->our_features,
+				  uc->our_features,
 				  peer->their_features,
 				  &uc->our_config,
 				  max_to_self_delay,