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| -rw-r--r-- | src/lib/hooks/callout_manager.cc | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/src/lib/hooks/callout_manager.cc b/src/lib/hooks/callout_manager.cc new file mode 100644 index 0000000..5505567 --- /dev/null +++ b/src/lib/hooks/callout_manager.cc @@ -0,0 +1,348 @@ +// Copyright (C) 2013-2021 Internet Systems Consortium, Inc. ("ISC") +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#include <config.h> + +#include <hooks/callout_handle.h> +#include <hooks/callout_manager.h> +#include <hooks/hooks_log.h> +#include <hooks/pointer_converter.h> +#include <util/stopwatch.h> + +#include <boost/static_assert.hpp> + +#include <algorithm> +#include <climits> +#include <functional> +#include <utility> + +using namespace std; + +namespace isc { +namespace hooks { + +// Constructor +CalloutManager::CalloutManager(int num_libraries) + : server_hooks_(ServerHooks::getServerHooks()), current_library_(-1), + hook_vector_(ServerHooks::getServerHooks().getCount()), + library_handle_(*this), pre_library_handle_(*this, 0), + post_library_handle_(*this, INT_MAX), num_libraries_(num_libraries) { + if (num_libraries < 0) { + isc_throw(isc::BadValue, "number of libraries passed to the " + "CalloutManager must be >= 0"); + } +} + +// Check that the index of a library is valid. It can range from 1 - n +// (n is the number of libraries), 0 (pre-user library callouts), or INT_MAX +// (post-user library callouts). It can also be -1 to indicate an invalid +// value. + +void +CalloutManager::checkLibraryIndex(int library_index) const { + if (((library_index >= -1) && (library_index <= num_libraries_)) || + (library_index == INT_MAX)) { + return; + } + + isc_throw(NoSuchLibrary, "library index " << library_index << + " is not valid for the number of loaded libraries (" << + num_libraries_ << ")"); +} + +// Register a callout for the current library. + +void +CalloutManager::registerCallout(const std::string& name, + CalloutPtr callout, + int library_index) { + // Note the registration. + LOG_DEBUG(callouts_logger, HOOKS_DBG_CALLS, HOOKS_CALLOUT_REGISTRATION) + .arg(library_index).arg(name); + + // Sanity check that the current library index is set to a valid value. + checkLibraryIndex(library_index); + + // New hooks could have been registered since the manager was constructed. + ensureHookLibsVectorSize(); + + // Get the index associated with this hook (validating the name in the + // process). + int hook_index = server_hooks_.getIndex(name); + + // Iterate through the callout vector for the hook from start to end, + // looking for the first entry where the library index is greater than + // the present index. + for (CalloutVector::iterator i = hook_vector_[hook_index].begin(); + i != hook_vector_[hook_index].end(); ++i) { + if (i->first > library_index) { + // Found an element whose library index number is greater than the + // current index, so insert the new element ahead of this one. + hook_vector_[hook_index].insert(i, make_pair(library_index, + callout)); + return; + } + } + + // Reached the end of the vector, so there is no element in the (possibly + // empty) set of callouts with a library index greater than the current + // library index. Inset the callout at the end of the list. + hook_vector_[hook_index].push_back(make_pair(library_index, callout)); +} + +// Check if callouts are present for a given hook index. + +bool +CalloutManager::calloutsPresent(int hook_index) const { + // Validate the hook index. + if ((hook_index < 0) || (hook_index >= hook_vector_.size())) { + isc_throw(NoSuchHook, "hook index " << hook_index << + " is not valid for the list of registered hooks"); + } + + // Valid, so are there any callouts associated with that hook? + return (!hook_vector_[hook_index].empty()); +} + +bool +CalloutManager::commandHandlersPresent(const std::string& command_name) const { + // Check if the hook point for the specified command exists. + int index = ServerHooks::getServerHooks().findIndex( + ServerHooks::commandToHookName(command_name)); + if (index >= 0) { + // The hook point exits but it is possible that there are no + // callouts/command handlers. This is possible if there was a + // hook library supporting this command attached, but it was + // later unloaded. The hook points are not deregistered in + // this case. Only callouts are deregistered. + // Let's check if callouts are present for this hook point. + return (calloutsPresent(index)); + } + + // Hook point not created, so we don't support this command in + // any of the hooks libraries. + return (false); +} + + +// Call all the callouts for a given hook. + +void +CalloutManager::callCallouts(int hook_index, CalloutHandle& callout_handle) { + // Clear the "skip" flag so we don't carry state from a previous call. + // This is done regardless of whether callouts are present to avoid passing + // any state from the previous call of callCallouts(). + callout_handle.setStatus(CalloutHandle::NEXT_STEP_CONTINUE); + + // Only initialize and iterate if there are callouts present. This check + // also catches the case of an invalid index. + if (calloutsPresent(hook_index)) { + + // Set the current hook index. This is used should a callout wish to + // determine to what hook it is attached. + callout_handle.setCurrentHook(hook_index); + + // This object will be used to measure execution time of each callout + // and the total time spent in callouts for this hook point. + util::Stopwatch stopwatch; + + // Mark that the callouts begin for the hook. + LOG_DEBUG(callouts_logger, HOOKS_DBG_CALLS, HOOKS_CALLOUTS_BEGIN) + .arg(server_hooks_.getName(callout_handle.getCurrentHook())); + + // Call all the callouts. + for (CalloutVector::const_iterator i = hook_vector_[hook_index].begin(); + i != hook_vector_[hook_index].end(); ++i) { + // In case the callout requires access to the context associated + // with the library, set the current library index to the index + // associated with the library that registered the callout being + // called. + callout_handle.setCurrentLibrary(i->first); + + // Call the callout + try { + stopwatch.start(); + int status = (*i->second)(callout_handle); + stopwatch.stop(); + if (status == 0) { + LOG_DEBUG(callouts_logger, HOOKS_DBG_EXTENDED_CALLS, + HOOKS_CALLOUT_CALLED) + .arg(callout_handle.getCurrentLibrary()) + .arg(server_hooks_.getName(callout_handle.getCurrentHook())) + .arg(PointerConverter(i->second).dlsymPtr()) + .arg(stopwatch.logFormatLastDuration()); + } else { + LOG_ERROR(callouts_logger, HOOKS_CALLOUT_ERROR) + .arg(server_hooks_.getName(callout_handle.getCurrentHook())) + .arg(callout_handle.getCurrentLibrary()) + .arg(PointerConverter(i->second).dlsymPtr()) + .arg(stopwatch.logFormatLastDuration()); + } + } catch (const std::exception& e) { + // If an exception occurred, the stopwatch.stop() hasn't been + // called, so we have to call it here. + stopwatch.stop(); + // Any exception, not just ones based on isc::Exception + LOG_ERROR(callouts_logger, HOOKS_CALLOUT_EXCEPTION) + .arg(server_hooks_.getName(callout_handle.getCurrentHook())) + .arg(callout_handle.getCurrentLibrary()) + .arg(PointerConverter(i->second).dlsymPtr()) + .arg(e.what()) + .arg(stopwatch.logFormatLastDuration()); + } + + } + + // Mark end of callout execution. Include the total execution + // time for callouts. + LOG_DEBUG(callouts_logger, HOOKS_DBG_CALLS, HOOKS_CALLOUTS_COMPLETE) + .arg(server_hooks_.getName(callout_handle.getCurrentHook())) + .arg(stopwatch.logFormatTotalDuration()); + + // Reset the current hook and library indexes to an invalid value to + // catch any programming errors. + callout_handle.setCurrentHook(-1); + callout_handle.setCurrentLibrary(-1); + } +} + +void +CalloutManager::callCommandHandlers(const std::string& command_name, + CalloutHandle& callout_handle) { + // Get the index of the hook point for the specified command. + // This will throw an exception if the hook point doesn't exist. + // The caller should check if the hook point exists by calling + // commandHandlersPresent. + int index = ServerHooks::getServerHooks().getIndex( + ServerHooks::commandToHookName(command_name)); + // Call the handlers for this command. + callCallouts(index, callout_handle); +} + + +// Deregister a callout registered by the current library on a particular hook. + +bool +CalloutManager::deregisterCallout(const std::string& name, CalloutPtr callout, + int library_index) { + // Sanity check that the current library index is set to a valid value. + checkLibraryIndex(library_index); + + // New hooks could have been registered since the manager was constructed. + ensureHookLibsVectorSize(); + + // Get the index associated with this hook (validating the name in the + // process). + int hook_index = server_hooks_.getIndex(name); + + // New hooks can have been registered since the manager was constructed. + if (hook_index >= hook_vector_.size()) { + return (false); + } + + /// Construct a CalloutEntry matching the current library and the callout + /// we want to remove. + CalloutEntry target(library_index, callout); + + /// To decide if any entries were removed, we'll record the initial size + /// of the callout vector for the hook, and compare it with the size after + /// the removal. + size_t initial_size = hook_vector_[hook_index].size(); + + // The next bit is standard STL (see "Item 33" in "Effective STL" by + // Scott Meyers). + // + // remove_if reorders the hook vector so that all items not matching + // the predicate are at the start of the vector and returns a pointer + // to the next element. (In this case, the predicate is that the item + // is equal to the value of the passed callout.) The erase() call + // removes everything from that element to the end of the vector, i.e. + // all the matching elements. + hook_vector_[hook_index].erase(remove_if(hook_vector_[hook_index].begin(), + hook_vector_[hook_index].end(), + [&target] (CalloutEntry x) { + return (x == target); }), + hook_vector_[hook_index].end()); + + // Return an indication of whether anything was removed. + bool removed = initial_size != hook_vector_[hook_index].size(); + if (removed) { + LOG_DEBUG(callouts_logger, HOOKS_DBG_EXTENDED_CALLS, + HOOKS_CALLOUT_DEREGISTERED).arg(library_index).arg(name); + } + + return (removed); +} + +// Deregister all callouts on a given hook. + +bool +CalloutManager::deregisterAllCallouts(const std::string& name, + int library_index) { + // New hooks could have been registered since the manager was constructed. + ensureHookLibsVectorSize(); + + // Get the index associated with this hook (validating the name in the + // process). + int hook_index = server_hooks_.getIndex(name); + + /// Construct a CalloutEntry matching the current library (the callout + /// pointer is NULL as we are not checking that). + CalloutEntry target(library_index, static_cast<CalloutPtr>(0)); + + /// To decide if any entries were removed, we'll record the initial size + /// of the callout vector for the hook, and compare it with the size after + /// the removal. + size_t initial_size = hook_vector_[hook_index].size(); + + // Remove all callouts matching this library. + hook_vector_[hook_index].erase(remove_if(hook_vector_[hook_index].begin(), + hook_vector_[hook_index].end(), + [&target] (CalloutEntry x) { + return (x.first == target.first); + }), + hook_vector_[hook_index].end()); + + // Return an indication of whether anything was removed. + bool removed = initial_size != hook_vector_[hook_index].size(); + if (removed) { + LOG_DEBUG(callouts_logger, HOOKS_DBG_EXTENDED_CALLS, + HOOKS_ALL_CALLOUTS_DEREGISTERED).arg(library_index).arg(name); + } + + return (removed); +} + +void +CalloutManager::registerCommandHook(const std::string& command_name) { + // New hooks could have been registered since the manager was constructed. + ensureHookLibsVectorSize(); + + ServerHooks& hooks = ServerHooks::getServerHooks(); + int hook_index = hooks.findIndex(ServerHooks::commandToHookName(command_name)); + if (hook_index < 0) { + // Hook for this command doesn't exist. Let's create one. + hooks.registerHook(ServerHooks::commandToHookName(command_name)); + // Callout Manager's vector of hooks have to be resized to hold the + // information about callouts for this new hook point. This should + // add new element at the end of the hook_vector_. The index of this + // element will match the index of the hook point in the ServerHooks + // because ServerHooks allocates indexes incrementally. + hook_vector_.resize(server_hooks_.getCount()); + } +} + +void +CalloutManager::ensureHookLibsVectorSize() { + ServerHooks& hooks = ServerHooks::getServerHooks(); + if (hooks.getCount() > hook_vector_.size()) { + // Uh oh, there are more hook points that our vector allows. + hook_vector_.resize(hooks.getCount()); + } +} + +} // namespace util +} // namespace isc |