json: add a param parser for a txid

common/json_helpers.c

@@ -68,3 +68,10 @@ bool json_to_short_channel_id(const char *buffer, const jsmntok_t *tok,
 					  tok->end - tok->start, scid,
 					  may_be_deprecated_form));
 }
+
+bool json_to_txid(const char *buffer, const jsmntok_t *tok,
+		  struct bitcoin_txid *txid)
+{
+	return bitcoin_txid_from_hex(buffer + tok->start,
+				     tok->end - tok->start, txid);
+}

common/json_helpers.h

@@ -2,6 +2,7 @@
 #ifndef LIGHTNING_COMMON_JSON_HELPERS_H
 #define LIGHTNING_COMMON_JSON_HELPERS_H
 #include "config.h"
+#include <bitcoin/tx.h>
 #include <common/json.h>
 
 struct amount_msat;
@@ -35,4 +36,7 @@ bool json_to_sat(const char *buffer, const jsmntok_t *tok,
 bool json_to_msat(const char *buffer, const jsmntok_t *tok,
 		  struct amount_msat *msat);
 
+/* Extract a bitcoin txid from this */
+bool json_to_txid(const char *buffer, const jsmntok_t *tok,
+		  struct bitcoin_txid *txid);
 #endif /* LIGHTNING_COMMON_JSON_HELPERS_H */

lightningd/json.c

@@ -108,6 +108,21 @@ struct command_result *param_pubkey(struct command *cmd, const char *name,
 			    json_tok_full(buffer, tok));
 }
 
+struct command_result *param_txid(struct command *cmd,
+				  const char *name,
+				  const char *buffer,
+				  const jsmntok_t *tok,
+				  struct bitcoin_txid **txid)
+{
+	*txid = tal(cmd, struct bitcoin_txid);
+	if (json_to_txid(buffer, tok, *txid))
+		return NULL;
+	return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			    "'%s' should be txid, not '%.*s'",
+			    name, json_tok_full_len(tok),
+			    json_tok_full(buffer, tok));
+}
+
 void json_add_short_channel_id(struct json_stream *response,
 			       const char *fieldname,
 			       const struct short_channel_id *scid)

lightningd/json.h

@@ -54,6 +54,9 @@ struct command_result *param_pubkey(struct command *cmd, const char *name,
 				    const char *buffer, const jsmntok_t *tok,
 				    struct pubkey **pubkey);
 
+struct command_result *param_txid(struct command *cmd, const char *name,
+				  const char *buffer, const jsmntok_t *tok,
+				  struct bitcoin_txid **txid);
 /* Makes sure *id is valid. */
 struct command_result *param_node_id(struct command *cmd,
 					       const char *name,

lightningd/test/run-jsonrpc.c

@@ -34,6 +34,10 @@ bool json_to_short_channel_id(const char *buffer UNNEEDED, const jsmntok_t *tok
 			      struct short_channel_id *scid UNNEEDED,
 			      bool may_be_deprecated_form UNNEEDED)
 { fprintf(stderr, "json_to_short_channel_id called!\n"); abort(); }
+/* Generated stub for json_to_txid */
+bool json_to_txid(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
+		  struct bitcoin_txid *txid UNNEEDED)
+{ fprintf(stderr, "json_to_txid called!\n"); abort(); }
 /* Generated stub for log_ */
 void log_(struct log *log UNNEEDED, enum log_level level UNNEEDED, const char *fmt UNNEEDED, ...)