plugin: Parse response for htlc_accepted hook

Signed-off-by: Christian Decker <decker.christian@gmail.com>

contrib/plugins/helloworld.py

@@ -38,7 +38,7 @@ def on_disconnect(plugin, id):
 def on_htlc_accepted(onion, htlc, plugin):
     plugin.log('on_htlc_accepted called')
     time.sleep(20)
-    return None
+    return {'result': 'continue'}
 
 
 plugin.add_option('greeting', 'Hello', 'The greeting I should use.')

lightningd/peer_htlcs.c

@@ -1,3 +1,4 @@
+#include <bitcoin/preimage.h>
 #include <bitcoin/tx.h>
 #include <ccan/build_assert/build_assert.h>
 #include <ccan/cast/cast.h>
@@ -624,10 +625,22 @@ struct htlc_accepted_hook_payload {
 	u8 *next_onion;
 };
 
+/* The possible return value types that a plugin may return for the
+ * `htlc_accepted` hook. */
+enum htlc_accepted_result {
+	htlc_accepted_continue,
+	htlc_accepted_fail,
+	htlc_accepted_resolve,
+};
+
 /**
  * Response type from the plugin
  */
 struct htlc_accepted_hook_response {
+	enum htlc_accepted_result result;
+	struct preimage payment_key;
+	enum onion_type failure_code;
+	u8 *channel_update;
 };
 
 /**
@@ -637,7 +650,64 @@ static struct htlc_accepted_hook_response *
 htlc_accepted_hook_deserialize(const tal_t *ctx, const char *buffer,
 			       const jsmntok_t *toks)
 {
-	return NULL;
+	struct htlc_accepted_hook_response *response;
+	const jsmntok_t *resulttok, *failcodetok, *paykeytok, *chanupdtok;
+
+	if (!toks || !buffer)
+		return NULL;
+
+	resulttok = json_get_member(buffer, toks, "result");
+
+	/* If the result is "continue" we can just return NULL since
+	 * this is the default behavior for this hook anyway */
+	if (!resulttok) {
+		fatal("Plugin return value does not contain 'result' key %s",
+		      json_strdup(tmpctx, buffer, toks));
+	}
+
+	if (json_tok_streq(buffer, resulttok, "continue")) {
+		return NULL;
+	}
+
+	response = tal(ctx, struct htlc_accepted_hook_response);
+	if (json_tok_streq(buffer, resulttok, "fail")) {
+		response->result = htlc_accepted_fail;
+		failcodetok = json_get_member(buffer, toks, "failure_code");
+		chanupdtok = json_get_member(buffer, toks, "channel_update");
+		if (failcodetok && !json_to_number(buffer, failcodetok,
+						   &response->failure_code))
+			fatal("Plugin provided a non-numeric failcode "
+			      "in response to an htlc_accepted hook");
+
+		if (!failcodetok)
+			response->failure_code = WIRE_TEMPORARY_NODE_FAILURE;
+
+		if (chanupdtok)
+			response->channel_update =
+			    json_tok_bin_from_hex(response, buffer, chanupdtok);
+		else
+			response->channel_update = NULL;
+
+	} else if (json_tok_streq(buffer, resulttok, "resolve")) {
+		response->result = htlc_accepted_resolve;
+		paykeytok = json_get_member(buffer, toks, "payment_key");
+		if (!paykeytok)
+			fatal(
+			    "Plugin did not specify a 'payment_key' in return "
+			    "value to the htlc_accepted hook: %s",
+			    json_strdup(tmpctx, buffer, resulttok));
+
+		if (!json_to_preimage(buffer, paykeytok,
+				      &response->payment_key))
+			fatal("Plugin specified an invalid 'payment_key': %s",
+			      json_tok_full(buffer, resulttok));
+	} else {
+		fatal("Plugin responded with an unknown result to the "
+		      "htlc_accepted hook: %s",
+		      json_strdup(tmpctx, buffer, resulttok));
+	}
+
+	return response;
 }
 
 static void htlc_accepted_hook_serialize(struct htlc_accepted_hook_payload *p,
@@ -679,29 +749,53 @@ htlc_accepted_hook_callback(struct htlc_accepted_hook_payload *request,
 	struct channel *channel = request->channel;
 	struct lightningd *ld = request->ld;
 	u8 *req;
+	enum htlc_accepted_result result;
+	struct htlc_accepted_hook_response *response;
+	response = htlc_accepted_hook_deserialize(request, buffer, toks);
 
-	/* TODO(cdecker) Assign to *response once we actually use it */
+	if (response)
-	htlc_accepted_hook_deserialize(request, buffer, toks);
+		result = response->result;
-
+	else
-	if (rs->nextcase == ONION_FORWARD) {
+		result = htlc_accepted_continue;
-		struct gossip_resolve *gr = tal(ld, struct gossip_resolve);
+
-
+	switch (result) {
-		gr->next_onion = tal_steal(gr, request->next_onion);
+	case htlc_accepted_continue:
-		gr->next_channel = rs->hop_data.channel_id;
+		if (rs->nextcase == ONION_FORWARD) {
-		gr->amt_to_forward = rs->hop_data.amt_forward;
+			struct gossip_resolve *gr =
-		gr->outgoing_cltv_value = rs->hop_data.outgoing_cltv;
+			    tal(ld, struct gossip_resolve);
-		gr->hin = hin;
+
+			gr->next_onion = tal_steal(gr, request->next_onion);
+			serialize_onionpacket(gr, rs->next);
+			gr->next_channel = rs->hop_data.channel_id;
+			gr->amt_to_forward = rs->hop_data.amt_forward;
+			gr->outgoing_cltv_value = rs->hop_data.outgoing_cltv;
+			gr->hin = hin;
+
+			req = towire_gossip_get_channel_peer(tmpctx,
+							     &gr->next_channel);
+			log_debug(
+			    channel->log, "Asking gossip to resolve channel %s",
+			    type_to_string(tmpctx, struct short_channel_id,
+					   &gr->next_channel));
+			subd_req(hin, ld->gossip, req, -1, 0,
+				 channel_resolve_reply, gr);
+		} else
+			handle_localpay(hin, hin->cltv_expiry,
+					&hin->payment_hash,
+					rs->hop_data.amt_forward,
+					rs->hop_data.outgoing_cltv);
+
+		break;
+	case htlc_accepted_fail:
+		log_debug(channel->log,
+			  "Failing incoming HTLC as instructed by plugin hook");
+		fail_in_htlc(hin, response->failure_code, NULL, NULL);
+		break;
+	case htlc_accepted_resolve:
+		fulfill_htlc(hin, &response->payment_key);
+		break;
+	}
 
-		req = towire_gossip_get_channel_peer(tmpctx, &gr->next_channel);
-		log_debug(channel->log, "Asking gossip to resolve channel %s",
-			  type_to_string(tmpctx, struct short_channel_id,
-					 &gr->next_channel));
-		subd_req(hin, ld->gossip, req, -1, 0,
-			 channel_resolve_reply, gr);
-	} else
-		handle_localpay(hin, hin->cltv_expiry, &hin->payment_hash,
-				rs->hop_data.amt_forward,
-				rs->hop_data.outgoing_cltv);
 	tal_free(request);
 }
 

wallet/test/run-wallet.c

@@ -299,9 +299,15 @@ void json_object_end(struct json_stream *js UNNEEDED)
 /* Generated stub for json_object_start */
 void json_object_start(struct json_stream *ks UNNEEDED, const char *fieldname UNNEEDED)
 { fprintf(stderr, "json_object_start called!\n"); abort(); }
+/* Generated stub for json_strdup */
+char *json_strdup(const tal_t *ctx UNNEEDED, const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED)
+{ fprintf(stderr, "json_strdup called!\n"); abort(); }
 /* Generated stub for json_stream_success */
 struct json_stream *json_stream_success(struct command *cmd UNNEEDED)
 { fprintf(stderr, "json_stream_success called!\n"); abort(); }
+/* Generated stub for json_tok_bin_from_hex */
+u8 *json_tok_bin_from_hex(const tal_t *ctx UNNEEDED, const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED)
+{ fprintf(stderr, "json_tok_bin_from_hex called!\n"); abort(); }
 /* Generated stub for json_tok_channel_id */
 bool json_tok_channel_id(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
 			 struct channel_id *cid UNNEEDED)
@@ -319,6 +325,17 @@ bool json_tok_streq(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
 bool json_to_node_id(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
 			       struct node_id *id UNNEEDED)
 { fprintf(stderr, "json_to_node_id called!\n"); abort(); }
+/* Generated stub for json_to_number */
+bool json_to_number(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
+		    unsigned int *num UNNEEDED)
+{ fprintf(stderr, "json_to_number called!\n"); abort(); }
+/* Generated stub for json_to_preimage */
+bool json_to_preimage(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED, struct preimage *preimage UNNEEDED)
+{ fprintf(stderr, "json_to_preimage called!\n"); abort(); }
+/* Generated stub for json_to_pubkey */
+bool json_to_pubkey(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
+		    struct pubkey *pubkey UNNEEDED)
+{ fprintf(stderr, "json_to_pubkey called!\n"); abort(); }
 /* Generated stub for json_to_short_channel_id */
 bool json_to_short_channel_id(const char *buffer UNNEEDED, const jsmntok_t *tok UNNEEDED,
 			      struct short_channel_id *scid UNNEEDED,