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#include "snmp-agent.hh"
#include "misc.hh"
#include "threadname.hh"
#ifdef RECURSOR
#include "logger.hh"
#else
#include "dolog.hh"
#endif
#ifdef HAVE_NET_SNMP
#ifndef HAVE_SNMP_SELECT_INFO2
/* that's terrible, because it means we are going to have trouble with large
FD numbers at some point.. */
# define netsnmp_large_fd_set fd_set
# define snmp_read2 snmp_read
# define snmp_select_info2 snmp_select_info
# define netsnmp_large_fd_set_init(...)
# define netsnmp_large_fd_set_cleanup(...)
# define NETSNMP_LARGE_FD_SET FD_SET
# define NETSNMP_LARGE_FD_CLR FD_CLR
# define NETSNMP_LARGE_FD_ZERO FD_ZERO
# define NETSNMP_LARGE_FD_ISSET FD_ISSET
#else
# include <net-snmp/library/large_fd_set.h>
#endif
const std::array<oid, 11> SNMPAgent::snmpTrapOID = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
int SNMPAgent::setCounter64Value(netsnmp_request_info* request,
uint64_t value)
{
struct counter64 val64;
val64.high = value >> 32;
val64.low = value & 0xffffffff;
snmp_set_var_typed_value(request->requestvb,
ASN_COUNTER64,
&val64,
sizeof(val64));
return SNMP_ERR_NOERROR;
}
bool SNMPAgent::sendTrap(pdns::channel::Sender<netsnmp_variable_list, void(*)(netsnmp_variable_list*)>& sender,
netsnmp_variable_list* varList)
{
try {
auto obj = std::unique_ptr<netsnmp_variable_list, void(*)(netsnmp_variable_list*)>(varList, snmp_free_varbind);
return sender.send(std::move(obj));
}
catch (...) {
return false;
}
}
void SNMPAgent::handleTrapsEvent()
{
try {
while (true) {
auto obj = d_receiver.receive(snmp_free_varbind);
if (!obj) {
break;
}
send_v2trap(obj->get());
}
}
catch (const std::exception& e) {
}
}
void SNMPAgent::handleSNMPQueryEvent(int fd)
{
netsnmp_large_fd_set fdset;
netsnmp_large_fd_set_init(&fdset, FD_SETSIZE);
NETSNMP_LARGE_FD_ZERO(&fdset);
NETSNMP_LARGE_FD_SET(fd, &fdset);
snmp_read2(&fdset);
}
void SNMPAgent::handleTrapsCB(int /* fd */, FDMultiplexer::funcparam_t& var)
{
SNMPAgent** agent = boost::any_cast<SNMPAgent*>(&var);
if (!agent || !*agent)
throw std::runtime_error("Invalid value received in SNMP trap callback");
(*agent)->handleTrapsEvent();
}
void SNMPAgent::handleSNMPQueryCB(int fd, FDMultiplexer::funcparam_t& var)
{
SNMPAgent** agent = boost::any_cast<SNMPAgent*>(&var);
if (!agent || !*agent)
throw std::runtime_error("Invalid value received in SNMP trap callback");
(*agent)->handleSNMPQueryEvent(fd);
}
#endif /* HAVE_NET_SNMP */
void SNMPAgent::worker()
{
#ifdef HAVE_NET_SNMP
FDMultiplexer* mplexer = FDMultiplexer::getMultiplexerSilent();
if (mplexer == nullptr) {
throw std::runtime_error("No FD multiplexer found for the SNMP agent!");
}
#ifdef RECURSOR
string threadName = "rec/snmp";
#else
string threadName = "dnsdist/SNMP";
#endif
setThreadName(threadName);
int maxfd = 0;
int block = 1;
netsnmp_large_fd_set fdset;
struct timeval timeout = { 0, 0 };
struct timeval now;
/* we want to be notified if a trap is waiting
to be sent */
mplexer->addReadFD(d_receiver.getDescriptor(), &handleTrapsCB, this);
while(true) {
netsnmp_large_fd_set_init(&fdset, FD_SETSIZE);
NETSNMP_LARGE_FD_ZERO(&fdset);
block = 1;
timeout = { 0, 0 };
snmp_select_info2(&maxfd, &fdset, &timeout, &block);
for (int fd = 0; fd < maxfd; fd++) {
if (NETSNMP_LARGE_FD_ISSET(fd, &fdset)) {
mplexer->addReadFD(fd, &handleSNMPQueryCB, this);
}
}
/* run updates now */
int res = mplexer->run(&now, (timeout.tv_sec * 1000) + (timeout.tv_usec / 1000));
/* we handle timeouts here, the rest has already been handled by callbacks */
if (res == 0) {
snmp_timeout();
run_alarms();
}
for (int fd = 0; fd < maxfd; fd++) {
if (NETSNMP_LARGE_FD_ISSET(fd, &fdset)) {
try {
mplexer->removeReadFD(fd);
}
catch(const FDMultiplexerException& e) {
/* we might get an exception when removing a closed file descriptor,
just ignore it */
}
}
}
}
#endif /* HAVE_NET_SNMP */
}
SNMPAgent::SNMPAgent([[maybe_unused]] const std::string& name, [[maybe_unused]] const std::string& daemonSocket)
{
#ifdef HAVE_NET_SNMP
netsnmp_enable_subagent();
snmp_disable_log();
if (!daemonSocket.empty()) {
netsnmp_ds_set_string(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_X_SOCKET,
daemonSocket.c_str());
}
/* no need to load any MIBS,
and it causes import errors if some modules are not present */
setenv("MIBS", "", 1);
init_agent(name.c_str());
/* we use select() so don't use SIGALARM to handle alarms.
Note that we need to handle alarms for automatic reconnection
to the daemon to work.
*/
netsnmp_ds_set_boolean(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_ALARM_DONT_USE_SIG,
1);
init_snmp(name.c_str());
auto [sender, receiver] = pdns::channel::createObjectQueue<netsnmp_variable_list, void(*)(netsnmp_variable_list*)>();
d_sender = std::move(sender);
d_receiver = std::move(receiver);
#endif /* HAVE_NET_SNMP */
}
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