zeroconf: Add alias_remote and alias_local to channel and DB

`alias_local` is generated locally and sent to the peer so it knows
what we're calling the channel, while `alias_remote` is received by
the peer so we know what to include in routehints when generating
invoices.

lightningd/channel.c

@@ -352,6 +352,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 			    bool remote_funding_locked,
 			    /* NULL or stolen */
 			    struct short_channel_id *scid,
+			    struct short_channel_id *alias_local STEALS,
+			    struct short_channel_id *alias_remote STEALS,
 			    struct channel_id *cid,
 			    struct amount_msat our_msat,
 			    struct amount_msat msat_to_us_min,
@@ -437,6 +439,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 	channel->our_funds = our_funds;
 	channel->remote_funding_locked = remote_funding_locked;
 	channel->scid = tal_steal(channel, scid);
+	channel->alias[LOCAL] = tal_steal(channel, alias_local);
+	channel->alias[REMOTE] = tal_steal(channel, alias_remote);  /* Haven't gotten one yet. */
 	channel->cid = *cid;
 	channel->our_msat = our_msat;
 	channel->msat_to_us_min = msat_to_us_min;

lightningd/channel.h

@@ -135,6 +135,12 @@ struct channel {
 	/* Channel if locked locally. */
 	struct short_channel_id *scid;
 
+	/* Alias used for option_zeroconf, or option_scid_alias, if
+	 * present. LOCAL are all the alias we told the peer about and
+	 * REMOTE is one of the aliases we got from the peer and we'll
+	 * use in a routehint. */
+	struct short_channel_id *alias[NUM_SIDES];
+
 	struct channel_id cid;
 
 	/* Amount going to us, not counting unfinished HTLCs; if we have one. */
@@ -278,6 +284,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 			    bool remote_funding_locked,
 			    /* NULL or stolen */
 			    struct short_channel_id *scid STEALS,
+			    struct short_channel_id *alias_local STEALS,
+			    struct short_channel_id *alias_remote STEALS,
 			    struct channel_id *cid,
 			    struct amount_msat our_msatoshi,
 			    struct amount_msat msatoshi_to_us_min,

lightningd/dual_open_control.c

@@ -33,6 +33,7 @@
 #include <lightningd/peer_fd.h>
 #include <lightningd/plugin_hook.h>
 #include <openingd/dualopend_wiregen.h>
+#include <sodium/randombytes.h>
 
 struct commit_rcvd {
 	struct channel *channel;
@@ -1239,6 +1240,12 @@ wallet_commit_channel(struct lightningd *ld,
 			= p2wpkh_for_keyidx(channel, channel->peer->ld,
 					    channel->final_key_idx);
 
+	 /* Can't have gotten their alias for this channel yet. */
+	channel->alias[REMOTE] = NULL;
+	/* We do generate one ourselves however. */
+	channel->alias[LOCAL] = tal(channel, struct short_channel_id);
+	randombytes_buf(channel->alias[LOCAL], sizeof(struct short_channel_id));
+
 	channel->remote_upfront_shutdown_script
 		= tal_steal(channel, remote_upfront_shutdown_script);
 

lightningd/opening_control.c

@@ -29,6 +29,7 @@
 #include <lightningd/plugin_hook.h>
 #include <lightningd/subd.h>
 #include <openingd/openingd_wiregen.h>
+#include <sodium/randombytes.h>
 #include <wally_psbt.h>
 
 void json_add_uncommitted_channel(struct json_stream *response,
@@ -99,6 +100,7 @@ wallet_commit_channel(struct lightningd *ld,
 	s64 final_key_idx;
 	u64 static_remotekey_start;
 	u32 lease_start_blockheight = 0; /* No leases on v1 */
+	struct short_channel_id *alias_local;
 
 	/* We cannot both be the fundee *and* have a `fundchannel_start`
 	 * command running!
@@ -158,6 +160,9 @@ wallet_commit_channel(struct lightningd *ld,
 	else
 		static_remotekey_start = 0x7FFFFFFFFFFFFFFF;
 
+	alias_local = tal(NULL, struct short_channel_id);
+	randombytes_buf(alias_local, sizeof(struct short_channel_id));
+
 	channel = new_channel(uc->peer, uc->dbid,
 			      NULL, /* No shachain yet */
 			      CHANNELD_AWAITING_LOCKIN,
@@ -174,6 +179,8 @@ wallet_commit_channel(struct lightningd *ld,
 			      local_funding,
 			      false, /* !remote_funding_locked */
 			      NULL, /* no scid yet */
+			      alias_local, /* But maybe we have an alias we want to use? */
+			      NULL, /* They haven't told us an alias yet */
 			      cid,
 			      /* The three arguments below are msatoshi_to_us,
 			       * msatoshi_to_us_min, and msatoshi_to_us_max.

wallet/db.c

@@ -875,6 +875,14 @@ static struct migration dbmigrations[] = {
     {SQL("ALTER TABLE forwarded_payments ADD forward_style INTEGER DEFAULT NULL"), NULL},
     /* "description" is used for label, so we use "paydescription" here */
     {SQL("ALTER TABLE payments ADD paydescription TEXT;"), NULL},
+    /* Alias we sent to the remote side, for zeroconf and
+     * option_scid_alias, can be a list of short_channel_ids if
+     * required, but keeping it a single SCID for now. */
+    {SQL("ALTER TABLE channels ADD alias_local BIGINT DEFAULT NULL"), NULL},
+    /* Alias we received from the peer, and which we should be using
+     * in routehints in invoices. The peer will remember all the
+     * aliases, but we only ever need one. */
+    {SQL("ALTER TABLE channels ADD alias_remote BIGINT DEFAULT NULL"), NULL},
 };
 
 /**

wallet/test/run-wallet.c

@@ -1589,6 +1589,8 @@ static bool test_channel_inflight_crud(struct lightningd *ld, const tal_t *ctx)
 			   funding_sats, AMOUNT_MSAT(0),
 			   our_sats,
 			   0, false,
+			   NULL, /* alias[LOCAL] */
+			   NULL, /* alias[REMOTE] */
 			   &cid,
 			   AMOUNT_MSAT(3333333000),
 			   AMOUNT_MSAT(33333),

wallet/wallet.c

@@ -1250,7 +1250,7 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 	struct channel_info channel_info;
 	struct fee_states *fee_states;
 	struct height_states *height_states;
-	struct short_channel_id *scid;
+	struct short_channel_id *scid, *alias[NUM_SIDES];
 	struct channel_id cid;
 	struct channel *chan;
 	u64 peer_dbid;
@@ -1291,6 +1291,20 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 		scid = NULL;
 	}
 
+	if (!db_col_is_null(stmt, "alias_local")) {
+		alias[LOCAL] = tal(tmpctx, struct short_channel_id);
+		alias[LOCAL]->u64 = db_col_u64(stmt, "alias_local");
+	} else {
+		alias[LOCAL] = NULL;
+	}
+
+	if (!db_col_is_null(stmt, "alias_remote")) {
+		alias[REMOTE] = tal(tmpctx, struct short_channel_id);
+		alias[REMOTE]->u64 = db_col_u64(stmt, "alias_remote");
+	} else {
+		alias[REMOTE] = NULL;
+	}
+
 	ok &= wallet_shachain_load(w, db_col_u64(stmt, "shachain_remote_id"),
 				   &wshachain);
 
@@ -1449,6 +1463,8 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 			   our_funding_sat,
 			   db_col_int(stmt, "funding_locked_remote") != 0,
 			   scid,
+			   alias[LOCAL],
+			   alias[REMOTE],
 			   &cid,
 			   our_msat,
 			   msat_to_us_min, /* msatoshi_to_us_min */
@@ -1583,6 +1599,8 @@ static bool wallet_channels_load_active(struct wallet *w)
 					", lease_chan_max_ppt"
 					", htlc_minimum_msat"
 					", htlc_maximum_msat"
+					", alias_local"
+					", alias_remote"
 					" FROM channels"
                                         " WHERE state != ?;")); //? 0
 	db_bind_int(stmt, 0, CLOSED);
@@ -1864,8 +1882,10 @@ void wallet_channel_save(struct wallet *w, struct channel *chan)
 					"  lease_chan_max_msat=?," // 40
 					"  lease_chan_max_ppt=?," // 41
 					"  htlc_minimum_msat=?," // 42
-					"  htlc_maximum_msat=?" // 43
+					"  htlc_maximum_msat=?," // 43
-					" WHERE id=?")); // 44
+					"  alias_local=?," // 44
+					"  alias_remote=?" // 45
+					" WHERE id=?")); // 46
 	db_bind_u64(stmt, 0, chan->their_shachain.id);
 	if (chan->scid)
 		db_bind_short_channel_id(stmt, 1, chan->scid);
@@ -1930,7 +1950,18 @@ void wallet_channel_save(struct wallet *w, struct channel *chan)
 	}
 	db_bind_amount_msat(stmt, 42, &chan->htlc_minimum_msat);
 	db_bind_amount_msat(stmt, 43, &chan->htlc_maximum_msat);
-	db_bind_u64(stmt, 44, chan->dbid);
+
+	if (chan->alias[LOCAL] != NULL)
+		db_bind_u64(stmt, 44, chan->alias[LOCAL]->u64);
+	else
+		db_bind_null(stmt, 44);
+
+	if (chan->alias[REMOTE] != NULL)
+		db_bind_u64(stmt, 45, chan->alias[REMOTE]->u64);
+	else
+		db_bind_null(stmt, 45);
+
+	db_bind_u64(stmt, 46, chan->dbid);
 	db_exec_prepared_v2(take(stmt));
 
 	wallet_channel_config_save(w, &chan->channel_info.their_config);