json: helper to parse pubkeys.

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

lightningd/gossip_control.c

@@ -262,8 +262,7 @@ static void json_getroute(struct command *cmd, const char *buffer, const jsmntok
 		return;
 	}
 
-	if (!pubkey_from_hexstr(buffer + idtok->start,
+	if (!json_tok_pubkey(buffer, idtok, &id)) {
-				idtok->end - idtok->start, &id)) {
 		command_fail(cmd, "Invalid id");
 		return;
 	}

lightningd/jsonrpc.c

@@ -352,6 +352,13 @@ void json_add_pubkey(struct json_result *response,
 	json_add_hex(response, fieldname, der, sizeof(der));
 }
 
+bool json_tok_pubkey(const char *buffer, const jsmntok_t *tok,
+		     struct pubkey *pubkey)
+{
+	return pubkey_from_hexstr(buffer + tok->start,
+				  tok->end - tok->start, pubkey);
+}
+
 void json_add_short_channel_id(struct json_result *response,
 			       const char *fieldname,
 			       const struct short_channel_id *id)

lightningd/jsonrpc.h

@@ -59,6 +59,10 @@ void json_add_pubkey(struct json_result *response,
 		     const char *fieldname,
 		     const struct pubkey *key);
 
+/* Extract a pubkey from this */
+bool json_tok_pubkey(const char *buffer, const jsmntok_t *tok,
+		     struct pubkey *pubkey);
+
 /* '"fieldname" : "1234:5:6"' */
 void json_add_short_channel_id(struct json_result *response,
 			       const char *fieldname,

lightningd/pay.c

@@ -232,9 +232,7 @@ static void json_sendpay(struct command *cmd,
 			command_fail(cmd, "route %zu invalid channel_id", n_hops);
 			return;
 		}
-		if (!pubkey_from_hexstr(buffer + idtok->start,
+		if (!json_tok_pubkey(buffer, idtok, &ids[n_hops])) {
-					idtok->end - idtok->start,
-					&ids[n_hops])) {
 			command_fail(cmd, "route %zu invalid id", n_hops);
 			return;
 		}

lightningd/peer_control.c

@@ -808,8 +808,7 @@ static void json_connect(struct command *cmd,
 		return;
 	}
 
-	if (!pubkey_from_hexstr(buffer + idtok->start,
+	if (!json_tok_pubkey(buffer, idtok, &id)) {
-				idtok->end - idtok->start, &id)) {
 		command_fail(cmd, "id %.*s not valid",
 			     idtok->end - idtok->start,
 			     buffer + idtok->start);
@@ -1015,8 +1014,7 @@ struct peer *peer_from_json(struct lightningd *ld,
 {
 	struct pubkey peerid;
 
-	if (!pubkey_from_hexstr(buffer + peeridtok->start,
+	if (!json_tok_pubkey(buffer, peeridtok, &peerid))
-				peeridtok->end - peeridtok->start, &peerid))
 		return NULL;
 
 	return peer_by_id(ld, &peerid);