Commit db9b5842 authored by Marcin Siodelski's avatar Marcin Siodelski

[3405] Install signal handlers in DHCPv4 server.

parent f9e491a5
......@@ -97,6 +97,14 @@ This error message is logged when the attempt to compute DHCID for a specified
lease has failed. The lease details and reason for failure is logged in the
message.
% DHCP4_DYNAMIC_RECONFIGURATION initate server reconfiguration using file: %1, after receiving SIGHUP signal
This is the info message logged when the DHCPv4 server starts reconfiguration
as a result of receiving SIGHUP signal.
% DHCP4_DYNAMIC_RECONFIGURATION_FAIL dynamic server reconfiguration failed with file: %1
This is an error message logged when the dynamic reconfiguration of the
DHCP server failed.
% DHCP4_EMPTY_HOSTNAME received empty hostname from the client, skipping processing of this option
This debug message is issued when the server received an empty Hostname option
from a client. Server does not process empty Hostname options and therefore
......
......@@ -175,6 +175,18 @@ Dhcpv4Srv::run() {
LOG_ERROR(dhcp4_logger, DHCP4_PACKET_RECEIVE_FAIL).arg(e.what());
}
// Handle next signal received by the process. It must be called after
// an attempt to receive a packet to properly handle server shut down.
// The SIGTERM or SIGINT will be received prior to, or during execution
// of select() (select is invoked by recivePacket()). When that happens,
// select will be interrupted. The signal handler will be invoked
// immediately after select(). The handler will set the shutdown flag
// and cause the process to terminate before the next select() function
// is called. If the function was called before receivePacket the
// process could wait up to the duration of timeout of select() to
// terminate.
handleSignal();
// Timeout may be reached or signal received, which breaks select()
// with no reception ocurred
if (!query) {
......
......@@ -25,11 +25,18 @@ using namespace isc::asiolink;
using namespace isc::dhcp;
using namespace std;
namespace isc {
namespace dhcp {
void
ControlledDhcpv4Srv::init(const std::string& file_name) {
namespace {
/// @brief Configure DHCPv4 server using the configuration file specified.
///
/// This function is used to both configure the DHCP server on its startup
/// and dynamically reconfigure the server when SIGHUP signal is received.
///
/// It fetches DHCPv6 server's configuration from the 'Dhcp4' section of
/// the JSON configuration file.
///
/// @param file_name Configuration file location.
void configure(const std::string& file_name) {
// This is a configuration backend implementation that reads the
// configuration from a JSON file.
......@@ -41,8 +48,8 @@ ControlledDhcpv4Srv::init(const std::string& file_name) {
try {
if (file_name.empty()) {
// Basic sanity check: file name must not be empty.
isc_throw(BadValue, "JSON configuration file not specified. Please "
"use -c command line option.");
isc_throw(isc::BadValue, "JSON configuration file not specified."
" Please use -c command line option.");
}
// Read contents of the file and parse it as JSON
......@@ -51,8 +58,8 @@ ControlledDhcpv4Srv::init(const std::string& file_name) {
if (!json) {
LOG_ERROR(dhcp4_logger, DHCP4_CONFIG_LOAD_FAIL)
.arg("Config file " + file_name + " missing or empty.");
isc_throw(BadValue, "Unable to process JSON configuration file:"
+ file_name);
isc_throw(isc::BadValue, "Unable to process JSON configuration"
" file: " << file_name);
}
// Get Dhcp4 component from the config
......@@ -60,29 +67,30 @@ ControlledDhcpv4Srv::init(const std::string& file_name) {
if (!dhcp4) {
LOG_ERROR(dhcp4_logger, DHCP4_CONFIG_LOAD_FAIL)
.arg("Config file " + file_name + " does not include 'Dhcp4' entry.");
isc_throw(BadValue, "Unable to process JSON configuration file:"
+ file_name);
.arg("Config file " + file_name + " does not include 'Dhcp4'"
" entry.");
isc_throw(isc::BadValue, "Unable to process JSON configuration"
" file: " << file_name);
}
// Use parsed JSON structures to configure the server
result = processCommand("config-reload", dhcp4);
result = ControlledDhcpv4Srv::processCommand("config-reload", dhcp4);
} catch (const std::exception& ex) {
LOG_ERROR(dhcp4_logger, DHCP4_CONFIG_LOAD_FAIL).arg(ex.what());
isc_throw(BadValue, "Unable to process JSON configuration file:"
+ file_name);
isc_throw(isc::BadValue, "Unable to process JSON configuration file: "
<< file_name);
}
if (!result) {
// Undetermined status of the configuration. This should never happen,
// but as the configureDhcp4Server returns a pointer, it is theoretically
// possible that it will return NULL.
// but as the configureDhcp4Server returns a pointer, it is
// theoretically possible that it will return NULL.
LOG_ERROR(dhcp4_logger, DHCP4_CONFIG_LOAD_FAIL)
.arg("Configuration failed: Undefined result of processCommand("
"config-reload, " + file_name + ")");
isc_throw(BadValue, "Configuration failed: Undefined result of "
"processCommand('config-reload', " + file_name + ")");
isc_throw(isc::BadValue, "Configuration failed: Undefined result of "
"processCommand('config-reload', " << file_name << ")");
}
// Now check is the returned result is successful (rcode=0) or not
......@@ -95,12 +103,64 @@ ControlledDhcpv4Srv::init(const std::string& file_name) {
reason = string(" (") + comment->stringValue() + string(")");
}
LOG_ERROR(dhcp4_logger, DHCP4_CONFIG_LOAD_FAIL).arg(reason);
isc_throw(BadValue, "Failed to apply configuration:" << reason);
isc_throw(isc::BadValue, "Failed to apply configuration: " << reason);
}
}
/// @brief Signals handler for DHCPv4 server.
///
/// This signal handler handles the following signals received by the DHCPv4
/// server process:
/// - SIGHUP - triggers server's dynamic reconfiguration.
/// - SIGTERM - triggers server's shut down.
/// - SIGINT - triggers server's shut down.
///
/// @param signo Signal number received.
void signalHandler(int signo) {
// SIGHUP signals a request to reconfigure the server.
if (signo == SIGHUP) {
// Get configuration file name.
std::string file = ControlledDhcpv4Srv::getInstance()->getConfigFile();
try {
LOG_INFO(dhcp4_logger, DHCP4_DYNAMIC_RECONFIGURATION).arg(file);
configure(file);
} catch (const std::exception& ex) {
// Log the unsuccessful reconfiguration. The reason for failure
// should be already logged. Don't rethrow an exception so as
// the server keeps working.
LOG_ERROR(dhcp4_logger, DHCP4_DYNAMIC_RECONFIGURATION_FAIL)
.arg(file);
}
} else if ((signo == SIGTERM) || (signo == SIGINT)) {
isc::data::ElementPtr params(new isc::data::MapElement());
ControlledDhcpv4Srv::processCommand("shutdown", params);
}
}
}
namespace isc {
namespace dhcp {
void
ControlledDhcpv4Srv::init(const std::string& file_name) {
// Call parent class's init to initialize file name.
Daemon::init(file_name);
// Configure the server using JSON file.
configure(file_name);
// We don't need to call openActiveSockets() or startD2() as these
// methods are called in processConfig() which is called by
// processCommand("reload-config", ...)
// Set signal handlers. When the SIGHUP is received by the process
// the server reconfiguration will be triggered. When SIGTERM or
// SIGINT will be received, the server will start shutting down.
signal_set_.reset(new isc::util::io::SignalSet(SIGINT, SIGHUP, SIGTERM));
// Set the pointer to the handler function.
signal_handler_ = signalHandler;
}
void ControlledDhcpv4Srv::cleanup() {
......
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