BOLT 12: switch invoice_request/invoice to singular chain field.

We keep the now-removed chains field, and in deprecated mode, we set it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-EXPERIMENTAL: bolt12: `chains` in invoice_request and invoice is deprecated, `chain` is used instead.

common/bolt12.c

@@ -3,6 +3,7 @@
 #include <common/bech32_util.h>
 #include <common/bolt12.h>
 #include <common/bolt12_merkle.h>
+#include <common/configdir.h>
 #include <common/features.h>
 #include <secp256k1_schnorrsig.h>
 #include <time.h>
@@ -46,6 +47,21 @@ bool bolt12_chains_match(const struct bitcoin_blkid *chains,
 	return false;
 }
 
+bool bolt12_chain_matches(const struct bitcoin_blkid *chain,
+			  const struct chainparams *must_be_chain,
+			  const struct bitcoin_blkid *deprecated_chains)
+{
+	/* Obsolete: We used to put an array in here, but we only ever
+	 * used a single value */
+	if (deprecated_apis && !chain)
+		chain = deprecated_chains;
+
+	if (!chain)
+		chain = &chainparams_for_network("bitcoin")->genesis_blockhash;
+
+	return bitcoin_blkid_eq(chain, &must_be_chain->genesis_blockhash);
+}
+
 static char *check_features_and_chain(const tal_t *ctx,
 				      const struct feature_set *our_features,
 				      const struct chainparams *must_be_chain,
@@ -231,7 +247,9 @@ struct tlv_invoice_request *invrequest_decode(const tal_t *ctx,
 	*fail = check_features_and_chain(ctx,
 					 our_features, must_be_chain,
 					 invrequest->features,
-					 invrequest->chains);
+					 invrequest->chain
+					 ? invrequest->chain
+					 : invrequest->chains);
 	if (*fail)
 		return tal_free(invrequest);
 
@@ -270,7 +288,8 @@ struct tlv_invoice *invoice_decode_nosig(const tal_t *ctx,
 	*fail = check_features_and_chain(ctx,
 					 our_features, must_be_chain,
 					 invoice->features,
-					 invoice->chains);
+					 invoice->chain
+					 ? invoice->chain : invoice->chains);
 	if (*fail)
 		return tal_free(invoice);
 

common/bolt12.h

@@ -103,6 +103,11 @@ bool bolt12_check_signature(const struct tlv_field *fields,
 bool bolt12_chains_match(const struct bitcoin_blkid *chains,
 			 const struct chainparams *must_be_chain);
 
+/* Given a single bolt12 chain, does it match?  (NULL == bitcoin) */
+bool bolt12_chain_matches(const struct bitcoin_blkid *chain,
+			  const struct chainparams *must_be_chain,
+			  const struct bitcoin_blkid *deprecated_chains);
+
 /* Given a basetime, when does period N start? */
 u64 offer_period_start(u64 basetime, size_t n,
 		       const struct tlv_offer_recurrence *recurrence);

common/test/run-bolt12_decode.c

@@ -7,6 +7,8 @@
 #include <ccan/tal/grab_file/grab_file.h>
 #include <ccan/tal/path/path.h>
 
+bool deprecated_apis = false;
+
 /* AUTOGENERATED MOCKS START */
 /* Generated stub for amount_asset_is_main */
 bool amount_asset_is_main(struct amount_asset *asset UNNEEDED)

common/test/run-bolt12_merkle.c

@@ -12,6 +12,8 @@
 /* Definition of n1 from the spec */
 #include <wire/peer_wire.h>
 
+bool deprecated_apis = false;
+
 /* AUTOGENERATED MOCKS START */
 /* Generated stub for features_unsupported */
 int features_unsupported(const struct feature_set *our_features UNNEEDED,

common/test/run-bolt12_period.c

@@ -5,6 +5,8 @@
 #include <ccan/tal/path/path.h>
 #include <common/setup.h>
 
+bool deprecated_apis = false;
+
 /* AUTOGENERATED MOCKS START */
 /* Generated stub for amount_asset_is_main */
 bool amount_asset_is_main(struct amount_asset *asset UNNEEDED)

devtools/bolt12-cli.c

@@ -19,6 +19,7 @@
 #define ERROR_USAGE 3
 
 static bool well_formed = true;
+bool deprecated_apis = true;
 
 /* Tal wrappers for opt. */
 static void *opt_allocfn(size_t size)
@@ -72,6 +73,12 @@ static void print_chains(const struct bitcoin_blkid *chains)
 	printf("\n");
 }
 
+static void print_chain(const struct bitcoin_blkid *chain)
+{
+	printf("chain: %s\n",
+	       type_to_string(tmpctx, struct bitcoin_blkid, chain));
+}
+
 static bool print_amount(const struct bitcoin_blkid *chains,
 			 const char *iso4217, u64 amount)
 {
@@ -532,16 +539,16 @@ int main(int argc, char *argv[])
 		if (!invreq)
 			errx(ERROR_BAD_DECODE, "Bad invoice_request: %s", fail);
 
-		if (invreq->chains)
-			print_chains(invreq->chains);
+		if (invreq->chain)
+			print_chain(invreq->chain);
 		if (must_have(invreq, payer_key))
 			print_payer_key(invreq->payer_key, invreq->payer_info);
 		if (invreq->payer_note)
 			print_payer_note(invreq->payer_note);
 		if (must_have(invreq, offer_id))
 			print_offer_id(invreq->offer_id);
 		if (must_have(invreq, amount))
-			well_formed &= print_amount(invreq->chains,
+			well_formed &= print_amount(invreq->chain,
 						    NULL,
 						    *invreq->amount);
 		if (invreq->features)
@@ -569,14 +576,14 @@ int main(int argc, char *argv[])
 		if (!invoice)
 			errx(ERROR_BAD_DECODE, "Bad invoice: %s", fail);
 
-		if (invoice->chains)
-			print_chains(invoice->chains);
+		if (invoice->chain)
+			print_chain(invoice->chain);
 
 		if (invoice->offer_id) {
 			print_offer_id(invoice->offer_id);
 		}
 		if (must_have(invoice, amount))
-			well_formed &= print_amount(invoice->chains,
+			well_formed &= print_amount(invoice->chain,
 						    NULL,
 						    *invoice->amount);
 		if (must_have(invoice, description))

doc/schemas/decode.schema.json

@@ -282,15 +282,11 @@
 			"type": "bip340sig",
 			"description": "BIP-340 signature of the *node_id* on this offer"
 		    },
-		    "chains": {
-			"type": "array",
-			"description": "which blockchains this offer is for (missing implies bitcoin mainnet only)",
-			"items": {
-			    "type": "hex",
-			    "description": "the genesis blockhash",
-			    "maxLength": 64,
-			    "minLength": 64
-			}
+		    "chain": {
+			"type": "hex",
+			"description": "which blockchain this invoice is for (missing implies bitcoin mainnet only)",
+			"maxLength": 64,
+			"minLength": 64
 		    },
 		    "amount_msat": {
 			"type": "msat",
@@ -450,7 +446,7 @@
 		    "offer_id": { },
 		    "node_id": { },
 		    "signature": { },
-		    "chains": { },
+		    "chain": { },
 		    "amount_msat": { },
 		    "send_invoice": { },
 		    "refund_for": { },
@@ -551,19 +547,15 @@
 		    "valid": { },
 		    "offer_id": {
 			"type": "hex",
-			"description": "the id of this offer (merkle hash of non-signature fields)",
+			"description": "the id of the offer this is requesting (merkle hash of non-signature fields)",
 			"maxLength": 64,
 			"minLength": 64
 		    },
-		    "chains": {
-			"type": "array",
-			"description": "which blockchains this offer is for (missing implies bitcoin mainnet only)",
-			"items": {
-			    "type": "hex",
-			    "description": "the genesis blockhash",
-			    "maxLength": 64,
-			    "minLength": 64
-			}
+		    "chain": {
+			"type": "hex",
+			"description": "which blockchain this invoice_request is for (missing implies bitcoin mainnet only)",
+			"maxLength": 64,
+			"minLength": 64
 		    },
 		    "amount_msat": {
 			"type": "msat",
@@ -620,7 +612,7 @@
 		    "type": { },
 		    "valid": { },
 		    "offer_id": { },
-		    "chains": { },
+		    "chain": { },
 		    "amount_msat": { },
 		    "features": { },
 		    "quantity": { },

plugins/fetchinvoice.c

@@ -1395,8 +1395,12 @@ static struct command_result *json_fetchinvoice(struct command *cmd,
 	 *   - the bitcoin chain is implied as the first and only entry.
 	 */
 	if (!streq(chainparams->network_name, "bitcoin")) {
-		invreq->chains = tal_arr(invreq, struct bitcoin_blkid, 1);
-		invreq->chains[0] = chainparams->genesis_blockhash;
+		if (deprecated_apis) {
+			invreq->chains = tal_arr(invreq, struct bitcoin_blkid, 1);
+			invreq->chains[0] = chainparams->genesis_blockhash;
+		}
+		invreq->chain = tal_dup(invreq, struct bitcoin_blkid,
+					&chainparams->genesis_blockhash);
 	}
 
 	invreq->features
@@ -1790,8 +1794,12 @@ static struct command_result *json_sendinvoice(struct command *cmd,
 	 *   - the bitcoin chain is implied as the first and only entry.
 	 */
 	if (!streq(chainparams->network_name, "bitcoin")) {
-		sent->inv->chains = tal_arr(sent->inv, struct bitcoin_blkid, 1);
-		sent->inv->chains[0] = chainparams->genesis_blockhash;
+		if (deprecated_apis) {
+			sent->inv->chains = tal_arr(sent->inv, struct bitcoin_blkid, 1);
+			sent->inv->chains[0] = chainparams->genesis_blockhash;
+		}
+		sent->inv->chain = tal_dup(sent->inv, struct bitcoin_blkid,
+					   &chainparams->genesis_blockhash);
 	}
 
 	sent->inv->features

plugins/offers.c

@@ -565,6 +565,8 @@ static void json_add_b12_invoice(struct json_stream *js,
 
 	if (invoice->chains)
 		json_add_chains(js, invoice->chains);
+	if (invoice->chain)
+		json_add_sha256(js, "chain", &invoice->chain->shad.sha);
 	if (invoice->offer_id)
 		json_add_sha256(js, "offer_id", invoice->offer_id);
 
@@ -700,7 +702,8 @@ static void json_add_b12_invoice(struct json_stream *js,
 		json_add_u32(js, "min_final_cltv_expiry", 18);
 
 	if (invoice->fallbacks)
-		valid &= json_add_fallbacks(js, invoice->chains,
+		valid &= json_add_fallbacks(js,
+					    invoice->chain ? invoice->chain : invoice->chains,
 					    invoice->fallbacks->fallbacks);
 
 	/* BOLT-offers #12:
@@ -749,6 +752,9 @@ static void json_add_invoice_request(struct json_stream *js,
 
 	if (invreq->chains)
 		json_add_chains(js, invreq->chains);
+	if (invreq->chain)
+		json_add_sha256(js, "chain", &invreq->chain->shad.sha);
+
 	/* BOLT-offers #12:
 	 * - MUST fail the request if `payer_key` is not present.
 	 * - MUST fail the request if `chains` does not include (or imply) a supported chain.

plugins/offers_inv_hook.c

@@ -369,10 +369,10 @@ struct command_result *handle_invoice(struct command *cmd,
 	 *   - MUST fail the request if `chains` does not include (or imply) a
 	 *     supported chain.
 	 */
-	if (!bolt12_chains_match(inv->inv->chains, chainparams)) {
+	if (!bolt12_chain_matches(inv->inv->chain, chainparams, inv->inv->chains)) {
 		return fail_inv(cmd, inv,
 				"Wrong chains %s",
-				tal_hex(tmpctx, inv->inv->chains));
+				tal_hex(tmpctx, inv->inv->chain));
 	}
 
 	/* BOLT-offers #12:

plugins/offers_invreq_hook.c

@@ -758,9 +758,14 @@ static struct command_result *listoffers_done(struct command *cmd,
 	 *     - MUST specify `chains` the offer is valid for.
 	 */
 	if (!streq(chainparams->network_name, "bitcoin")) {
-		ir->inv->chains = tal_arr(ir->inv, struct bitcoin_blkid, 1);
-		ir->inv->chains[0] = chainparams->genesis_blockhash;
+		if (deprecated_apis) {
+			ir->inv->chains = tal_arr(ir->inv, struct bitcoin_blkid, 1);
+			ir->inv->chains[0] = chainparams->genesis_blockhash;
+		}
+		ir->inv->chain = tal_dup(ir->inv, struct bitcoin_blkid,
+					 &chainparams->genesis_blockhash);
 	}
+
 	/* BOLT-offers #12:
 	 *   - MUST set `offer_id` to the id of the offer.
 	 */
@@ -883,10 +888,11 @@ struct command_result *handle_invoice_request(struct command *cmd,
 	 *   - MUST fail the request if `chains` does not include (or imply) a
 	 *     supported chain.
 	 */
-	if (!bolt12_chains_match(ir->invreq->chains, chainparams)) {
+	if (!bolt12_chain_matches(ir->invreq->chain, chainparams,
+				  ir->invreq->chains)) {
 		return fail_invreq(cmd, ir,
-				   "Wrong chains %s",
-				   tal_hex(tmpctx, ir->invreq->chains));
+				   "Wrong chain %s",
+				   tal_hex(tmpctx, ir->invreq->chain));
 	}
 
 	/* BOLT-offers #12:

wire/bolt12_exp_wire.csv

@@ -44,6 +44,8 @@ subtypedata,blinded_path,num_hops,byte,
 subtypedata,blinded_path,path,onionmsg_path,num_hops
 tlvtype,invoice_request,chains,2
 tlvdata,invoice_request,chains,chains,chain_hash,...
+tlvtype,invoice_request,chain,3
+tlvdata,invoice_request,chain,chain,chain_hash,
 tlvtype,invoice_request,offer_id,4
 tlvdata,invoice_request,offer_id,offer_id,sha256,
 tlvtype,invoice_request,amount,8
@@ -68,6 +70,8 @@ tlvtype,invoice_request,payer_signature,240
 tlvdata,invoice_request,payer_signature,sig,bip340sig,
 tlvtype,invoice,chains,2
 tlvdata,invoice,chains,chains,chain_hash,...
+tlvtype,invoice,chain,3
+tlvdata,invoice,chain,chain,chain_hash,
 tlvtype,invoice,offer_id,4
 tlvdata,invoice,offer_id,offer_id,sha256,
 tlvtype,invoice,amount,8

wire/bolt12_wire.csv

@@ -44,6 +44,8 @@ subtypedata,blinded_path,num_hops,byte,
 subtypedata,blinded_path,path,onionmsg_path,num_hops
 tlvtype,invoice_request,chains,2
 tlvdata,invoice_request,chains,chains,chain_hash,...
+tlvtype,invoice_request,chain,3
+tlvdata,invoice_request,chain,chain,chain_hash,
 tlvtype,invoice_request,offer_id,4
 tlvdata,invoice_request,offer_id,offer_id,sha256,
 tlvtype,invoice_request,amount,8
@@ -68,6 +70,8 @@ tlvtype,invoice_request,payer_signature,240
 tlvdata,invoice_request,payer_signature,sig,bip340sig,
 tlvtype,invoice,chains,2
 tlvdata,invoice,chains,chains,chain_hash,...
+tlvtype,invoice,chain,3
+tlvdata,invoice,chain,chain,chain_hash,
 tlvtype,invoice,offer_id,4
 tlvdata,invoice,offer_id,offer_id,sha256,
 tlvtype,invoice,amount,8