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Merge remote-tracking branch 'origin/topic/jsiwek/dns-mgr-fixes'

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* origin/topic/jsiwek/dns-mgr-fixes:
  Fix timing out DNS lookups that were already resolved
  Remove an unhelpful/optimistic DNS_Mgr optimization
  Fix DNS_Mgr priority_queue usage
  Remove dead code from DNS_Mgr
  Improve DNS_Mgr I/O loop: prevent starvation due to busy Broker
  Fix a ref counnting bug in DNS_Mgr
This commit is contained in:
Johanna Amann 2019-05-15 08:53:22 -07:00
commit 2bb529f5b7
4 changed files with 55 additions and 23 deletions
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6
CHANGES
View file

@ -1,4 +1,10 @@
2.6-300 | 2019-05-15 09:00:57 -0700
* Fixes to DNS lookup, including ref-counting bugs, preventing starvation
of the DNS_Mgr in the I/O loop, dead code removal, and a fix that
prevents the timeout of already resolved DNS lookups (Jon Siwek, Corelight)
2.6-292 | 2019-05-14 19:01:05 -0700
* Fix maybe-uninitialized compiler warning (Jon Siwek, Corelight)

2
VERSION
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@ -1 +1 @@
2.6-292
2.6-300

50
src/DNS_Mgr.cc
View file

@ -289,10 +289,13 @@ ListVal* DNS_Mapping::Addrs()
TableVal* DNS_Mapping::AddrsSet() {
ListVal* l = Addrs();
if ( l )
return l->ConvertToSet();
else
if ( ! l )
return empty_addr_set();
auto rval = l->ConvertToSet();
Unref(l);
return rval;
}
StringVal* DNS_Mapping::Host()
@ -389,6 +392,7 @@ DNS_Mgr::DNS_Mgr(DNS_MgrMode arg_mode)
successful = 0;
failed = 0;
nb_dns = nullptr;
next_timestamp = -1.0;
}
DNS_Mgr::~DNS_Mgr()
@ -1249,8 +1253,17 @@ void DNS_Mgr::GetFds(iosource::FD_Set* read, iosource::FD_Set* write,
double DNS_Mgr::NextTimestamp(double* network_time)
{
// This is kind of cheating ...
return asyncs_timeouts.size() ? timer_mgr->Time() : -1.0;
if ( asyncs_timeouts.empty() )
// No pending requests.
return -1.0;
if ( next_timestamp < 0 )
// Store the timestamp to help prevent starvation by some other
// IOSource always trying to use the same timestamp
// (assuming network_time does actually increase).
next_timestamp = timer_mgr->Time();
return next_timestamp;
}
void DNS_Mgr::CheckAsyncAddrRequest(const IPAddr& addr, bool timeout)
@ -1356,7 +1369,7 @@ void DNS_Mgr::CheckAsyncHostRequest(const char* host, bool timeout)
void DNS_Mgr::Flush()
{
DoProcess(false);
DoProcess();
HostMap::iterator it;
for ( it = host_mappings.begin(); it != host_mappings.end(); ++it )
@ -1378,10 +1391,11 @@ void DNS_Mgr::Flush()
void DNS_Mgr::Process()
{
DoProcess(false);
DoProcess();
next_timestamp = -1.0;
}
void DNS_Mgr::DoProcess(bool flush)
void DNS_Mgr::DoProcess()
{
if ( ! nb_dns )
return;
@ -1390,23 +1404,23 @@ void DNS_Mgr::DoProcess(bool flush)
{
AsyncRequest* req = asyncs_timeouts.top();
if ( req->time + DNS_TIMEOUT > current_time() || flush )
if ( req->time + DNS_TIMEOUT > current_time() )
break;
if ( req->IsAddrReq() )
CheckAsyncAddrRequest(req->host, true);
else if ( req->is_txt )
CheckAsyncTextRequest(req->name.c_str(), true);
else
CheckAsyncHostRequest(req->name.c_str(), true);
if ( ! req->processed )
{
if ( req->IsAddrReq() )
CheckAsyncAddrRequest(req->host, true);
else if ( req->is_txt )
CheckAsyncTextRequest(req->name.c_str(), true);
else
CheckAsyncHostRequest(req->name.c_str(), true);
}
asyncs_timeouts.pop();
delete req;
}
if ( asyncs_addrs.size() == 0 && asyncs_names.size() == 0 && asyncs_texts.size() == 0 )
return;
if ( AnswerAvailable(0) <= 0 )
return;

20
src/DNS_Mgr.h
View file

@ -132,7 +132,7 @@ protected:
void CheckAsyncTextRequest(const char* host, bool timeout);
// Process outstanding requests.
void DoProcess(bool flush);
void DoProcess();
// IOSource interface.
void GetFds(iosource::FD_Set* read, iosource::FD_Set* write,
@ -172,12 +172,13 @@ protected:
struct AsyncRequest {
double time;
bool is_txt;
bool processed;
IPAddr host;
string name;
bool is_txt;
CallbackList callbacks;
AsyncRequest() : time(0.0), is_txt(false) { }
AsyncRequest() : time(0.0), is_txt(false), processed(false) { }
bool IsAddrReq() const { return name.length() == 0; }
@ -190,6 +191,7 @@ protected:
delete *i;
}
callbacks.clear();
processed = true;
}
void Resolved(TableVal* addrs)
@ -201,6 +203,7 @@ protected:
delete *i;
}
callbacks.clear();
processed = true;
}
void Timeout()
@ -212,6 +215,7 @@ protected:
delete *i;
}
callbacks.clear();
processed = true;
}
};
@ -228,7 +232,14 @@ protected:
typedef list<AsyncRequest*> QueuedList;
QueuedList asyncs_queued;
typedef priority_queue<AsyncRequest*> TimeoutQueue;
struct AsyncRequestCompare {
bool operator()(const AsyncRequest* a, const AsyncRequest* b)
{
return a->time > b->time;
}
};
typedef priority_queue<AsyncRequest*, std::vector<AsyncRequest*>, AsyncRequestCompare> TimeoutQueue;
TimeoutQueue asyncs_timeouts;
int asyncs_pending;
@ -236,6 +247,7 @@ protected:
unsigned long num_requests;
unsigned long successful;
unsigned long failed;
double next_timestamp;
};
extern DNS_Mgr* dns_mgr;