decode: fix handling of blinded_payinfo.

Our pay code handles this correctly, but decode was still using an old model where there was a payinfo per hop, not per path. Reported-by: @t-bast See: #5823 Signed-off-by: Rusty Russell <[email protected]>
ElementsProject · Jan 30, 2023 · 2dec805 · 2dec805
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commit 2dec805
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Showing 3 changed files with 55 additions and 40 deletions.
diff --git a/doc/lightning-decode.7.md b/doc/lightning-decode.7.md
@@ -148,13 +148,14 @@ If **type** is "bolt12 invoice", and **valid** is *true*:
   - **invoice\_paths** (array of objects): Paths to pay the destination:
     - **first\_node\_id** (pubkey): the (presumably well-known) public key of the start of the path
     - **blinding** (pubkey): blinding factor for this path
+    - **payinfo** (object):
+      - **fee\_base\_msat** (msat): basefee for path
+      - **fee\_proportional\_millionths** (u32): proportional fee for path
+      - **cltv\_expiry\_delta** (u32): CLTV delta for path
+      - **features** (hex): features allowed for path
     - **path** (array of objects): an individual path:
       - **blinded\_node\_id** (pubkey): node\_id of the hop
       - **encrypted\_recipient\_data** (hex): encrypted TLV entry for this hop
-      - **fee\_base\_msat** (msat, optional): basefee for path
-      - **fee\_proportional\_millionths** (u32, optional): proportional fee for path
-      - **cltv\_expiry\_delta** (u32, optional): CLTV delta for path
-      - **features** (hex, optional): features allowed for path
   - **invoice\_created\_at** (u64): the UNIX timestamp of invoice creation
   - **invoice\_payment\_hash** (hex): the hash of the *payment\_preimage* (always 64 characters)
   - **invoice\_amount\_msat** (msat): the amount required to fulfill invoice
@@ -302,4 +303,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:eadd9b06e6cb495a794568f3a9e2371c09718311c0b61ad05b0fca3014c429d3)
+[comment]: # ( SHA256STAMP:a8843027b18a1d54efcf0ca423fc6fbe0c2136d32fa3d8c552a875b6844dd950)
diff --git a/doc/schemas/decode.schema.json b/doc/schemas/decode.schema.json
@@ -927,6 +927,7 @@
               "required": [
                 "first_node_id",
                 "blinding",
+                "payinfo",
                 "path"
               ],
               "additionalProperties": false,
@@ -939,6 +940,34 @@
                   "type": "pubkey",
                   "description": "blinding factor for this path"
                 },
+                "payinfo": {
+                  "type": "object",
+                  "required": [
+                    "fee_base_msat",
+                    "fee_proportional_millionths",
+                    "cltv_expiry_delta",
+                    "features"
+                  ],
+                  "additionalProperties": false,
+                  "properties": {
+                    "fee_base_msat": {
+                      "type": "msat",
+                      "description": "basefee for path"
+                    },
+                    "fee_proportional_millionths": {
+                      "type": "u32",
+                      "description": "proportional fee for path"
+                    },
+                    "cltv_expiry_delta": {
+                      "type": "u32",
+                      "description": "CLTV delta for path"
+                    },
+                    "features": {
+                      "type": "hex",
+                      "description": "features allowed for path"
+                    }
+                  }
+                },
                 "path": {
                   "type": "array",
                   "description": "an individual path",
@@ -957,22 +986,6 @@
                       "encrypted_recipient_data": {
                         "type": "hex",
                         "description": "encrypted TLV entry for this hop"
-                      },
-                      "fee_base_msat": {
-                        "type": "msat",
-                        "description": "basefee for path"
-                      },
-                      "fee_proportional_millionths": {
-                        "type": "u32",
-                        "description": "proportional fee for path"
-                      },
-                      "cltv_expiry_delta": {
-                        "type": "u32",
-                        "description": "CLTV delta for path"
-                      },
-                      "features": {
-                        "type": "hex",
-                        "description": "features allowed for path"
                       }
                     }
                   }

diff --git a/plugins/offers.c b/plugins/offers.c
@@ -249,21 +249,11 @@ static void json_add_chains(struct json_stream *js,
 
 static void json_add_onionmsg_path(struct json_stream *js,
 				   const char *fieldname,
-				   const struct onionmsg_hop *hop,
-				   const struct blinded_payinfo *payinfo)
+				   const struct onionmsg_hop *hop)
 {
 	json_object_start(js, fieldname);
 	json_add_pubkey(js, "blinded_node_id", &hop->blinded_node_id);
 	json_add_hex_talarr(js, "encrypted_recipient_data", hop->encrypted_recipient_data);
-	if (payinfo) {
-		json_add_amount_msat_only(js, "fee_base_msat",
-					  amount_msat(payinfo->fee_base_msat));
-		json_add_u32(js, "fee_proportional_millionths",
-			     payinfo->fee_proportional_millionths);
-		json_add_u32(js, "cltv_expiry_delta",
-			     payinfo->cltv_expiry_delta);
-		json_add_hex_talarr(js, "features", payinfo->features);
-	}
 	json_object_end(js);
 }
 
@@ -273,18 +263,28 @@ static bool json_add_blinded_paths(struct json_stream *js,
 				   struct blinded_path **paths,
 				   struct blinded_payinfo **blindedpay)
 {
-	size_t n = 0;
 	json_array_start(js, fieldname);
 	for (size_t i = 0; i < tal_count(paths); i++) {
 		json_object_start(js, NULL);
 		json_add_pubkey(js, "first_node_id", &paths[i]->first_node_id);
 		json_add_pubkey(js, "blinding", &paths[i]->blinding);
+
+		/* Don't crash if we're short a payinfo! */
+		if (i < tal_count(blindedpay)) {
+			json_object_start(js, "payinfo");
+			json_add_amount_msat_only(js, "fee_base_msat",
+						  amount_msat(blindedpay[i]->fee_base_msat));
+			json_add_u32(js, "fee_proportional_millionths",
+				     blindedpay[i]->fee_proportional_millionths);
+			json_add_u32(js, "cltv_expiry_delta",
+				     blindedpay[i]->cltv_expiry_delta);
+			json_add_hex_talarr(js, "features", blindedpay[i]->features);
+			json_object_end(js);
+		}
+
 		json_array_start(js, "path");
 		for (size_t j = 0; j < tal_count(paths[i]->path); j++) {
-			json_add_onionmsg_path(js, NULL, paths[i]->path[j],
-					       n < tal_count(blindedpay)
-					       ? blindedpay[n] : NULL);
-			n++;
+			json_add_onionmsg_path(js, NULL, paths[i]->path[j]);
 		}
 		json_array_end(js);
 		json_object_end(js);
@@ -295,9 +295,10 @@ static bool json_add_blinded_paths(struct json_stream *js,
 	 * - MUST reject the invoice if `invoice_blindedpay` does not contain
 	 *   exactly one `blinded_payinfo` per `invoice_paths`.`blinded_path`.
 	 */
-	if (blindedpay && n != tal_count(blindedpay)) {
-		json_add_string(js, "warning_invalid_invoice_blindedpay",
-				"invoice does not have correct number of blinded_payinfo");
+	if (blindedpay && tal_count(blindedpay) != tal_count(paths)) {
+		json_add_str_fmt(js, "warning_invalid_invoice_blindedpay",
+				 "invoice has %zu blinded_payinfo but %zu paths",
+				 tal_count(blindedpay), tal_count(paths));
 		return false;
 	}