interactive_tx: Add tx_abort support

We add checks for tx_abort and pass them back up to be handled.

common/interactivetx.c

@@ -128,8 +128,7 @@ static u8 *read_next_msg(const tal_t *ctx,
 		desc = is_peer_warning(msg, msg);
 		if (desc) {
 			status_info("They sent %s", desc);
-			tal_free(msg);
-			continue;
+			return tal_free(msg);
 		}
 
 		/* In theory, we're in the middle of an open/RBF/splice, but
@@ -142,9 +141,8 @@ static u8 *read_next_msg(const tal_t *ctx,
 		case WIRE_TX_ADD_OUTPUT:
 		case WIRE_TX_REMOVE_OUTPUT:
 		case WIRE_TX_COMPLETE:
-			return msg;
 		case WIRE_TX_ABORT:
-			/* TODO */
+			return msg;
 		case WIRE_TX_SIGNATURES:
 		case WIRE_CHANNEL_READY:
 		case WIRE_TX_INIT_RBF:
@@ -345,13 +343,16 @@ bool interactivetx_has_changes(struct interactivetx_context *ictx,
 
 char *process_interactivetx_updates(const tal_t *ctx,
 			 	    struct interactivetx_context *ictx,
-				    bool *received_tx_complete)
+				    bool *received_tx_complete,
+				    u8 **abort_msg)
 {
 	bool we_complete = false, they_complete = false;
 	u8 *msg;
 	char *error = NULL;
 	struct wally_psbt *next_psbt;
 
+	*abort_msg = NULL;
+
 	if (received_tx_complete)
 		they_complete = *received_tx_complete;
 
@@ -696,7 +697,8 @@ char *process_interactivetx_updates(const tal_t *ctx,
 				*received_tx_complete = true;
 			break;
 		case WIRE_TX_ABORT:
-			/* Todo */
+			*abort_msg = msg;
+			return NULL;
 		case WIRE_INIT:
 		case WIRE_ERROR:
 		case WIRE_WARNING:

common/interactivetx.h

@@ -77,10 +77,13 @@ struct interactivetx_context *new_interactivetx_context(const tal_t *ctx,
  * out -> true means the last message from the peer was 'tx_complete'.
  *
  * Returns NULL on success or a description of the error on failure.
+ *
+ * If `tx_abort` is received, NULL is returned and `abort_msg` will be set to
  */
 char *process_interactivetx_updates(const tal_t *ctx,
 				    struct interactivetx_context *ictx,
-				    bool *received_tx_complete);
+				    bool *received_tx_complete,
+				    u8 **abort_msg);
 
 /* If the given ictx would cause `process_interactivetx_updates to send tx
  * changes when called. Returns true if an error occurs