offer / offerout: return existing if its still active.

As requested by @shesek: it's weird to fail if they ask for the exact
same thing (which is quite possible, since offers don't expire by
default).

And add a new "created" field so they can tell if they have an old
one.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

doc/lightning-offer.7

@@ -10,9 +10,10 @@ lightning-offer - Command for accepting payments
 
 .SH DESCRIPTION
 
-The \fBoffer\fR RPC command creates an offer, which is a precursor to
-creating one or more invoices\.  It automatically enables the processing of
-an incoming invoice_request, and issuing of invoices\.
+The \fBoffer\fR RPC command creates an offer (or returns an existing
+one), which is a precursor to creating one or more invoices\.  It
+automatically enables the processing of an incoming invoice_request,
+and issuing of invoices\.
 
 
 Note that it creates two variants of the offer: a signed and an
@@ -119,7 +120,9 @@ On success, an object is returned, containing:
 .IP \[bu]
 \fBbolt12_unsigned\fR (string): the bolt12 encoding of the offer, without a signature
 .IP \[bu]
-\fBused\fR (boolean): True if an associated invoice has been paid (always \fIfalse\fR)
+\fBused\fR (boolean): True if an associated invoice has been paid
+.IP \[bu]
+\fBcreated\fR (boolean): false if the offer already existed
 .IP \[bu]
 \fBlabel\fR (string, optional): the (optional) user-specified label
 
@@ -131,13 +134,17 @@ lightning process fails before responding, the caller should use
 not\.
 
 
+If the offer already existed, and is still active, that is returned;
+if it's not active then this call fails\.
+
+
 The following error codes may occur:
 
 .RS
 .IP \[bu]
 -1: Catchall nonspecific error\.
 .IP \[bu]
-1000: Offer with this offer_id already exists\.
+1000: Offer with this offer_id already exists (but is not active)\.
 
 .RE
 .SH AUTHOR
@@ -152,4 +159,4 @@ Rusty Russell \fI<rusty@rustcorp.com.au\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:f7faf86c7cb052200c3b4d6e3d6209afa54600cc7a33e1082583a2766d02a275
+\" SHA256STAMP:bd1bae6f6b56d4efa95e17b7aff042b897acacdd783cef7df0dd729f6c9b5d8f

doc/lightning-offer.7.md

@@ -11,9 +11,10 @@ SYNOPSIS
 DESCRIPTION
 -----------
 
-The **offer** RPC command creates an offer, which is a precursor to
-creating one or more invoices.  It automatically enables the processing of
-an incoming invoice_request, and issuing of invoices.
+The **offer** RPC command creates an offer (or returns an existing
+one), which is a precursor to creating one or more invoices.  It
+automatically enables the processing of an incoming invoice_request,
+and issuing of invoices.
 
 Note that it creates two variants of the offer: a signed and an
 unsigned one (which is smaller).  Wallets should accept both: the
@@ -100,7 +101,8 @@ On success, an object is returned, containing:
 - **single_use** (boolean): whether this expires as soon as it's paid (reflects the *single_use* parameter)
 - **bolt12** (string): the bolt12 encoding of the offer
 - **bolt12_unsigned** (string): the bolt12 encoding of the offer, without a signature
-- **used** (boolean): True if an associated invoice has been paid (always *false*)
+- **used** (boolean): True if an associated invoice has been paid
+- **created** (boolean): false if the offer already existed
 - **label** (string, optional): the (optional) user-specified label
 [comment]: # (GENERATE-FROM-SCHEMA-END)
 
@@ -109,9 +111,12 @@ lightning process fails before responding, the caller should use
 lightning-listoffers(7) to query whether this offer was created or
 not.
 
+If the offer already existed, and is still active, that is returned;
+if it's not active then this call fails.
+
 The following error codes may occur:
 - -1: Catchall nonspecific error.
-- 1000: Offer with this offer_id already exists.
+- 1000: Offer with this offer_id already exists (but is not active).
 
 AUTHOR
 ------
@@ -128,4 +133,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:0f9cfd3cc68aaba20af0eee763c93b475016619d960e3f5bbc0b762a809f0fef)
+[comment]: # ( SHA256STAMP:53f1460e28d45129b2c00b7116c87eb47a5b717f7912f499e864f4aa28b320fa)

doc/lightning-offerout.7

@@ -73,6 +73,8 @@ On success, an object is returned, containing:
 .IP \[bu]
 \fBused\fR (boolean): True if an incoming invoice has been paid (always \fIfalse\fR)
 .IP \[bu]
+\fBcreated\fR (boolean): false if the offer already existed
+.IP \[bu]
 \fBlabel\fR (string, optional): the (optional) user-specified label
 
 .RE
@@ -113,4 +115,4 @@ Rusty Russell \fI<rusty@rustcorp.com.au\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:3de11c6de7905322d9ef748981fc1d4f9ca91f4be46d76af6e9124572853047d
+\" SHA256STAMP:4998ef3e06f37823c969a524fc3deb96b58eb2babee560df27e3f006fc535186

doc/lightning-offerout.7.md

@@ -61,6 +61,7 @@ On success, an object is returned, containing:
 - **bolt12** (string): the bolt12 encoding of the offer
 - **bolt12_unsigned** (string): the bolt12 encoding of the offer, without a signature
 - **used** (boolean): True if an incoming invoice has been paid (always *false*)
+- **created** (boolean): false if the offer already existed
 - **label** (string, optional): the (optional) user-specified label
 [comment]: # (GENERATE-FROM-SCHEMA-END)
 
@@ -97,4 +98,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:2b7e7b543a88a10dbfbca2508e034af79f43ed0845abdb9df1fdf7e28ee33c26)
+[comment]: # ( SHA256STAMP:14fada9336956a08b6d55c4ce01fcb62726cbdef9a065f1966335f61c4e91ce5)

doc/schemas/offer.schema.json

@@ -2,7 +2,7 @@
     "$schema": "http://json-schema.org/draft-07/schema#",
     "type": "object",
     "additionalProperties": false,
-    "required": [ "offer_id", "active", "single_use", "bolt12", "bolt12_unsigned", "used" ],
+    "required": [ "offer_id", "active", "single_use", "bolt12", "bolt12_unsigned", "used", "created" ],
     "properties": {
 	"offer_id": {
 	    "type": "hex",
@@ -29,9 +29,12 @@
 	},
 	"used": {
 	    "type": "boolean",
-	    "enum": [ false ],
 	    "description": "True if an associated invoice has been paid"
 	},
+	"created": {
+	    "type": "boolean",
+	    "description": "false if the offer already existed"
+	},
 	"label": {
 	    "type": "string",
 	    "description": "the (optional) user-specified label"

doc/schemas/offerout.schema.json

@@ -2,7 +2,7 @@
     "$schema": "http://json-schema.org/draft-07/schema#",
     "type": "object",
     "additionalProperties": false,
-    "required": [ "offer_id", "active", "single_use", "bolt12", "bolt12_unsigned", "used" ],
+    "required": [ "offer_id", "active", "single_use", "bolt12", "bolt12_unsigned", "used", "created" ],
     "properties": {
 	"offer_id": {
 	    "type": "hex",
@@ -33,6 +33,10 @@
 	    "enum": [ false ],
 	    "description": "True if an incoming invoice has been paid"
 	},
+	"created": {
+	    "type": "boolean",
+	    "description": "false if the offer already existed"
+	},
 	"label": {
 	    "type": "string",
 	    "description": "the (optional) user-specified label"

lightningd/offer.c

@@ -1,3 +1,4 @@
+#include <ccan/cast/cast.h>
 #include <common/bolt12.h>
 #include <common/bolt12_merkle.h>
 #include <common/configdir.h>
@@ -91,6 +92,7 @@ static struct command_result *json_createoffer(struct command *cmd,
 	bool *single_use;
 	enum offer_status status;
 	struct pubkey32 key;
+	bool created;
 
 	if (!param(cmd, buffer, params,
 		   p_req("bolt12", param_b12_offer, &offer),
@@ -110,17 +112,28 @@ static struct command_result *json_createoffer(struct command *cmd,
 	hsm_sign_b12(cmd->ld, "offer", "signature", &merkle, NULL, &key,
 		     offer->signature);
 	b12str = offer_encode(cmd, offer);
-	if (!wallet_offer_create(cmd->ld->wallet, &merkle, b12str, label,
-				 status)) {
-		return command_fail(cmd,
-				    OFFER_ALREADY_EXISTS,
-				    "Duplicate offer");
-	}
+
+	/* If it already exists, we use that one instead (and then
+	 * the offer plugin will complain if it's inactive or expired) */
+	if (!wallet_offer_create(cmd->ld->wallet, &merkle,
+				 b12str, label, status)) {
+		if (!wallet_offer_find(cmd, cmd->ld->wallet, &merkle,
+				       cast_const2(const struct json_escape **,
+						   &label),
+				       &status)) {
+			return command_fail(cmd, LIGHTNINGD,
+					    "Could not create, nor find offer");
+		}
+		created = false;
+	} else
+		created = true;
+
 	offer->signature = tal_free(offer->signature);
 	b12str_nosig = offer_encode(cmd, offer);
 
 	response = json_stream_success(cmd);
 	json_populate_offer(response, &merkle, b12str, b12str_nosig, label, status);
+	json_add_bool(response, "created", created);
 	return command_success(cmd, response);
 }
 

plugins/offers_offer.c

@@ -255,6 +255,31 @@ struct offer_info {
 	bool *single_use;
 };
 
+static struct command_result *check_result(struct command *cmd,
+					   const char *buf,
+					   const jsmntok_t *result,
+					   void *arg UNNEEDED)
+{
+	bool active;
+
+	/* If it's inactive, we can't return it, */
+	if (!json_to_bool(buf, json_get_member(buf, result, "active"),
+			  &active)) {
+		return command_fail(cmd,
+				    LIGHTNINGD,
+				    "Bad creaoffer status reply %.*s",
+				    json_tok_full_len(result),
+				    json_tok_full(buf, result));
+	}
+	if (!active)
+		return command_fail(cmd,
+				    OFFER_ALREADY_EXISTS,
+				    "Offer already exists, but isn't active");
+
+	/* Otherwise, push through the result. */
+	return forward_result(cmd, buf, result, arg);
+}
+
 static struct command_result *create_offer(struct command *cmd,
 					   struct offer_info *offinfo)
 {
@@ -262,7 +287,7 @@ static struct command_result *create_offer(struct command *cmd,
 
 	/* We simply pass this through. */
 	req = jsonrpc_request_start(cmd->plugin, cmd, "createoffer",
-				    forward_result, forward_error,
+				    check_result, forward_error,
 				    offinfo);
 	json_add_string(req->js, "bolt12",
 			offer_encode(tmpctx, offinfo->offer));
@@ -436,9 +461,8 @@ struct command_result *json_offerout(struct command *cmd,
 
 	offer->node_id = tal_dup(offer, struct pubkey32, &id);
 
-	/* We simply pass this through. */
 	req = jsonrpc_request_start(cmd->plugin, cmd, "createoffer",
-				    forward_result, forward_error,
+				    check_result, forward_error,
 				    offer);
 	json_add_string(req->js, "bolt12", offer_encode(tmpctx, offer));
 	if (label)

tests/test_pay.py

@@ -4122,6 +4122,7 @@ def test_fetchinvoice(node_factory, bitcoind):
     # Simple offer first.
     offer1 = l3.rpc.call('offer', {'amount': '2msat',
                                    'description': 'simple test'})
+    assert offer1['created'] is True
 
     inv1 = l1.rpc.call('fetchinvoice', {'offer': offer1['bolt12']})
     inv2 = l1.rpc.call('fetchinvoice', {'offer': offer1['bolt12_unsigned'],
@@ -4274,6 +4275,15 @@ def test_fetchinvoice(node_factory, bitcoind):
     # But we can still pay the (already-converted) invoice.
     l1.rpc.pay(inv['invoice'])
 
+    # Identical creation gives it again, just with created false.
+    offer1 = l3.rpc.call('offer', {'amount': '2msat',
+                                   'description': 'simple test'})
+    assert offer1['created'] is False
+    l3.rpc.call('disableoffer', {'offer_id': offer1['offer_id']})
+    with pytest.raises(RpcError, match="1000.*Offer already exists, but isn't active"):
+        l3.rpc.call('offer', {'amount': '2msat',
+                              'description': 'simple test'})
+
     # Test timeout.
     l3.stop()
     with pytest.raises(RpcError, match='Timeout waiting for response'):