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#include <ccan/io/io.h>
#include <ccan/list/list.h>
#include <common/configdir.h>
#include <common/memleak.h>
#include <lightningd/jsonrpc.h>
#include <lightningd/plugin_hook.h>
#include <wallet/db.h>
#include <wallet/db_common.h>
/* Struct containing all the information needed to deserialize and
* dispatch an eventual plugin_hook response. */
struct plugin_hook_request {
struct list_head call_chain;
struct plugin *plugin;
const struct plugin_hook *hook;
void *cb_arg;
void *payload;
struct db *db;
struct lightningd *ld;
};
/* A link in the plugin_hook call chain (there's a joke in there about
* computer scientists and naming...). The purpose is to act both as a list
* from which elements can be popped off as we progress along the chain as
* well as have a way for plugins to notify about their untimely demise during
* a hook call.
*/
struct plugin_hook_call_link {
struct list_node list;
struct plugin *plugin;
struct plugin_hook_request *req;
};
static struct plugin_hook *plugin_hook_by_name(const char *name)
{
static struct plugin_hook **hooks = NULL;
static size_t num_hooks;
if (!hooks)
hooks = autodata_get(hooks, &num_hooks);
for (size_t i=0; i<num_hooks; i++)
if (streq(hooks[i]->name, name))
return hooks[i];
return NULL;
}
bool plugin_hook_register(struct plugin *plugin, const char *method)
{
struct plugin_hook *hook = plugin_hook_by_name(method);
if (!hook) {
/* No such hook name registered */
return false;
}
/* Make sure the plugins array is initialized. */
if (hook->plugins == NULL)
hook->plugins = notleak(tal_arr(NULL, struct plugin *, 0));
/* If this is a single type hook and we have a plugin registered we
* must fail this attempt to add the plugin to the hook. */
if (hook->type == PLUGIN_HOOK_SINGLE && tal_count(hook->plugins) > 0)
return false;
/* Ensure we don't register the same plugin multple times. */
for (size_t i=0; i<tal_count(hook->plugins); i++)
if (hook->plugins[i] == plugin)
return true;
/* Ok, we're sure they can register and they aren't yet registered, so
* register them. */
tal_arr_expand(&hook->plugins, plugin);
return true;
}
bool plugin_hook_unregister(struct plugin *plugin, const char *method)
{
struct plugin_hook *hook = plugin_hook_by_name(method);
if (!hook || !hook->plugins) {
/* No such hook name registered */
return false;
}
for (size_t i = 0; i < tal_count(hook->plugins); i++) {
if (hook->plugins[i] == plugin) {
tal_arr_remove(&hook->plugins, i);
return true;
}
}
return false;
}
void plugin_hook_unregister_all(struct plugin *plugin)
{
static struct plugin_hook **hooks = NULL;
static size_t num_hooks;
if (!hooks)
hooks = autodata_get(hooks, &num_hooks);
for (size_t i = 0; i < num_hooks; i++)
plugin_hook_unregister(plugin, hooks[i]->name);
}
/* Mutual recursion */
static void plugin_hook_call_next(struct plugin_hook_request *ph_req);
static void plugin_hook_callback(const char *buffer, const jsmntok_t *toks,
const jsmntok_t *idtok,
struct plugin_hook_request *r);
/* We get notified if a plugin was killed while it was part of a call
* chain. If it was still to be called we just remove it from the list,
* otherwise it was the plugin that was currently handling the hook call, and
* we need to fail over to the next plugin.
*/
static void plugin_hook_killed(struct plugin_hook_call_link *link)
{
struct plugin_hook_call_link *head;
head = list_top(&link->req->call_chain, struct plugin_hook_call_link,
list);
/* If we are the head of the call chain, then the plugin died while it
* was handling the hook call. Pretend it didn't get the memo by
* calling the next one instead. This is correct since it is
* equivalent to the plugin dying before the hook invokation, assuming
* the plugin has not commmitted any changes internally. This is the
* weakest assumption we can make short of restarting the plugin and
* calling the hook again (potentially crashing the plugin the same
* way again.
*/
if (link == head) {
/* Call next will unlink, so we don't need to. This is treated
* equivalent to the plugin returning a continue-result.
*/
plugin_hook_callback(NULL, NULL, NULL, link->req);
} else {
/* The plugin is in the list waiting to be called, just remove
* it from the list. */
list_del(&link->list);
}
}
/**
* Callback to be passed to the jsonrpc_request.
*
* Unbundles the arguments, deserializes the response and dispatches
* it to the hook callback.
*/
static void plugin_hook_callback(const char *buffer, const jsmntok_t *toks,
const jsmntok_t *idtok,
struct plugin_hook_request *r)
{
const jsmntok_t *resulttok, *resrestok;
struct db *db = r->db;
bool more_plugins, cont;
struct plugin_hook_call_link *last, *it;
if (r->ld->state == LD_STATE_SHUTDOWN) {
log_debug(r->ld->log,
"Abandoning plugin hook call due to shutdown");
return;
}
/* Pop the head off the call chain and continue with the next */
last = list_pop(&r->call_chain, struct plugin_hook_call_link, list);
assert(last != NULL);
tal_del_destructor(last, plugin_hook_killed);
tal_free(last);
if (buffer) {
resulttok = json_get_member(buffer, toks, "result");
if (!resulttok)
fatal("Plugin for %s returned non-result response %.*s",
r->hook->name, toks->end - toks->start,
buffer + toks->start);
resrestok = json_get_member(buffer, resulttok, "result");
} else {
/* Buffer and / or resulttok could be used by the reponse_cb
* to identify no-result responses. So make sure both are
* set */
resulttok = NULL;
/* cppcheck isn't smart enough to notice that `resrestok`
* doesn't need to be initialized in the expression
* initializing `cont`, so set it to NULL to shut it up. */
resrestok = NULL;
}
/* If this is a hook response containing a `continue` and we have more
* plugins queue the next call. In that case we discard the remainder
* of the result, and let the next plugin decide. */
cont = buffer == NULL || (resrestok && json_tok_streq(buffer, resrestok, "continue"));
more_plugins = !list_empty(&r->call_chain);
if (cont && more_plugins) {
plugin_hook_call_next(r);
} else {
db_begin_transaction(db);
r->hook->response_cb(r->cb_arg, buffer, resulttok);
db_commit_transaction(db);
/* We need to remove the destructors from the remaining
* call-chain, otherwise they'd still be called when the
* plugin dies or we shut down. */
list_for_each(&r->call_chain, it, list) {
tal_del_destructor(it, plugin_hook_killed);
tal_steal(r, it);
}
tal_free(r);
}
}
static void plugin_hook_call_next(struct plugin_hook_request *ph_req)
{
struct jsonrpc_request *req;
const struct plugin_hook *hook = ph_req->hook;
assert(!list_empty(&ph_req->call_chain));
ph_req->plugin = list_top(&ph_req->call_chain, struct plugin_hook_call_link, list)->plugin;
req = jsonrpc_request_start(NULL, hook->name,
plugin_get_log(ph_req->plugin),
plugin_hook_callback, ph_req);
hook->serialize_payload(ph_req->payload, req->stream);
jsonrpc_request_end(req);
plugin_request_send(ph_req->plugin, req);
}
void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
void *payload, void *cb_arg)
{
struct plugin_hook_request *ph_req;
struct plugin_hook_call_link *link;
if (tal_count(hook->plugins)) {
/* If we have a plugin that has registered for this
* hook, serialize and call it */
/* FIXME: technically this is a leak, but we don't
* currently have a list to store these. We might want
* to eventually to inspect in-flight requests. */
ph_req = notleak(tal(hook->plugins, struct plugin_hook_request));
ph_req->hook = hook;
ph_req->cb_arg = cb_arg;
ph_req->db = ld->wallet->db;
ph_req->payload = tal_steal(ph_req, payload);
ph_req->ld = ld;
list_head_init(&ph_req->call_chain);
for (size_t i=0; i<tal_count(hook->plugins); i++) {
/* We allocate this off of the plugin so we get notified if the plugin dies. */
link = tal(hook->plugins[i], struct plugin_hook_call_link);
link->plugin = hook->plugins[i];
link->req = ph_req;
tal_add_destructor(link, plugin_hook_killed);
list_add_tail(&ph_req->call_chain, &link->list);
}
plugin_hook_call_next(ph_req);
} else {
/* If no plugin has registered for this hook, just
* call the callback with a NULL result. Saves us the
* roundtrip to the serializer and deserializer. If we
* were expecting a default response it should have
* been part of the `cb_arg`. */
hook->response_cb(cb_arg, NULL, NULL);
}
}
/* We open-code this, because it's just different and special enough to be
* annoying, and to make it clear that it's totally synchronous. */
/* Special synchronous hook for db */
static struct plugin_hook db_write_hook = {"db_write", PLUGIN_HOOK_SINGLE, NULL,
NULL, NULL};
AUTODATA(hooks, &db_write_hook);
static void db_hook_response(const char *buffer, const jsmntok_t *toks,
const jsmntok_t *idtok,
struct plugin_hook_request *ph_req)
{
const jsmntok_t *resulttok;
resulttok = json_get_member(buffer, toks, "result");
if (!resulttok)
fatal("Plugin returned an invalid response to the db_write "
"hook: %s", buffer);
#ifdef COMPAT_V080
/* For back-compatibility we allow to return a simple Boolean true. */
if (deprecated_apis) {
bool resp;
if (json_to_bool(buffer, resulttok, &resp)) {
static bool warned = false;
/* If it fails, we must not commit to our db. */
if (!resp)
fatal("Plugin returned failed db_write: %s.",
buffer);
if (!warned) {
warned = true;
log_unusual(ph_req->db->log,
"Plugin returned 'true' to "
"'db_hook'. "
"This is now deprecated and "
"you should return "
"{'result': 'continue'} "
"instead.");
}
/* Resume. */
io_break(ph_req);
return;
}
}
#endif /* defined(COMPAT_V080) */
/* We expect result: { 'result' : 'continue' }.
* Anything else we abort.
*/
resulttok = json_get_member(buffer, resulttok, "result");
if (resulttok) {
if (!json_tok_streq(buffer, resulttok, "continue"))
fatal("Plugin returned failed db_write: %s.", buffer);
} else
fatal("Plugin returned an invalid result to the db_write "
"hook: %s", buffer);
/* We're done, exit exclusive loop. */
io_break(ph_req);
}
void plugin_hook_db_sync(struct db *db)
{
const struct plugin_hook *hook = &db_write_hook;
struct jsonrpc_request *req;
struct plugin_hook_request *ph_req;
void *ret;
struct plugin *plugin;
const char **changes = db_changes(db);
if (tal_count(hook->plugins) == 0)
return;
ph_req = notleak(tal(hook->plugins, struct plugin_hook_request));
/* FIXME: do IO logging for this! */
req = jsonrpc_request_start(NULL, hook->name, NULL, db_hook_response,
ph_req);
ph_req->hook = hook;
ph_req->db = db;
plugin = ph_req->plugin = hook->plugins[0];
json_add_num(req->stream, "data_version", db_data_version_get(db));
json_array_start(req->stream, "writes");
for (size_t i = 0; i < tal_count(changes); i++)
json_add_string(req->stream, NULL, changes[i]);
json_array_end(req->stream);
jsonrpc_request_end(req);
plugin_request_send(ph_req->plugin, req);
/* We can be called on way out of an io_loop, which is already breaking.
* That will make this immediately return; save the break value and call
* again, then hand it onwards. */
ret = plugin_exclusive_loop(plugin);
if (ret != ph_req) {
void *ret2 = plugin_exclusive_loop(plugin);
assert(ret2 == ph_req);
io_break(ret);
}
}