BIND 10 trac598, updated. 0194cb0aaf6c8137e0699b8166c746a0c8a6302c [trac598] Implement the simplest forwarder by refactoring the code.
BIND 10 source code commits
bind10-changes at lists.isc.org
Fri Apr 8 09:11:49 UTC 2011
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- Log -----------------------------------------------------------------
commit 0194cb0aaf6c8137e0699b8166c746a0c8a6302c
Author: zhanglikun <zhanglikun at cnnic.cn>
Date: Fri Apr 8 17:07:10 2011 +0800
[trac598] Implement the simplest forwarder by refactoring the code.
-----------------------------------------------------------------------
Summary of changes:
src/lib/asiolink/recursive_query.cc | 94 +++++++----------------------------
1 files changed, 18 insertions(+), 76 deletions(-)
-----------------------------------------------------------------------
diff --git a/src/lib/asiolink/recursive_query.cc b/src/lib/asiolink/recursive_query.cc
index 55aec7a..8de3dc0 100644
--- a/src/lib/asiolink/recursive_query.cc
+++ b/src/lib/asiolink/recursive_query.cc
@@ -454,7 +454,7 @@ public:
}
};
-class ForwardQuery : public IOFetch::Callback {
+class UpstreamQuery : public IOFetch::Callback {
private:
// The io service to handle async calls
IOService& io_;
@@ -480,28 +480,17 @@ private:
*/
// Timeout information
int query_timeout_;
- unsigned retries_;
-
- // normal query state
// TODO: replace by our wrapper
asio::deadline_timer client_timer;
asio::deadline_timer lookup_timer;
- size_t queries_out_;
-
- // If we timed out ourselves (lookup timeout), stop issuing queries
- bool done_;
-
// If we have a client timeout, we send back an answer, but don't
// stop. We use this variable to make sure we don't send another
// answer if we do find one later (or if we have a lookup_timeout)
bool answer_sent_;
- // Reference to our cache
- isc::cache::ResolverCache& cache_;
-
- // (re)send the query to the server.
+ // send the query to the server.
void send() {
const int uc = upstream_->size();
buffer_->clear();
@@ -517,20 +506,17 @@ private:
upstream_->at(serverIndex).second,
buffer_, this, query_timeout_);
- ++queries_out_;
io_.get_io_service().post(query);
}
public:
- ForwardQuery(IOService& io,
+ UpstreamQuery(IOService& io,
ConstMessagePtr query_message,
MessagePtr answer_message,
boost::shared_ptr<AddressVector> upstream,
OutputBufferPtr buffer,
isc::resolve::ResolverInterface::CallbackPtr cb,
- int query_timeout, int client_timeout, int lookup_timeout,
- unsigned retries,
- isc::cache::ResolverCache& cache) :
+ int query_timeout, int client_timeout, int lookup_timeout) :
io_(io),
query_message_(query_message),
answer_message_(answer_message),
@@ -538,26 +524,22 @@ public:
buffer_(buffer),
resolvercallback_(cb),
query_timeout_(query_timeout),
- retries_(retries),
client_timer(io.get_io_service()),
lookup_timer(io.get_io_service()),
- queries_out_(0),
- done_(false),
- answer_sent_(false),
- cache_(cache)
+ answer_sent_(false)
{
// Setup the timer to stop trying (lookup_timeout)
if (lookup_timeout >= 0) {
lookup_timer.expires_from_now(
boost::posix_time::milliseconds(lookup_timeout));
- lookup_timer.async_wait(boost::bind(&ForwardQuery::stop, this, false));
+ lookup_timer.async_wait(boost::bind(&UpstreamQuery::stop, this, false));
}
// Setup the timer to send an answer (client_timeout)
if (client_timeout >= 0) {
client_timer.expires_from_now(
boost::posix_time::milliseconds(client_timeout));
- client_timer.async_wait(boost::bind(&ForwardQuery::clientTimeout, this));
+ client_timer.async_wait(boost::bind(&UpstreamQuery::clientTimeout, this));
}
send();
@@ -582,29 +564,8 @@ public:
// here again.
// same goes if we have an outstanding query (can't delete
// until that one comes back to us)
- done_ = true;
if (resume && !answer_sent_) {
answer_sent_ = true;
-
- // There are two types of messages we could store in the
- // cache;
- // 1. answers to our fetches from authoritative servers,
- // exactly as we receive them, and
- // 2. answers to queries we received from clients, which
- // have received additional processing (following CNAME
- // chains, for instance)
- //
- // Doing only the first would mean we would have to re-do
- // processing when we get data from our cache, and doing
- // only the second would miss out on the side-effect of
- // having nameserver data in our cache.
- //
- // So right now we do both. Since the cache (currently)
- // stores Messages on their question section only, this
- // does mean that we overwrite the messages we stored in
- // the previous iteration if we are following a delegation.
- cache_.update(*answer_message_);
-
resolvercallback_->success(answer_message_);
} else {
resolvercallback_->failure();
@@ -615,30 +576,22 @@ public:
if (client_timer.cancel() != 0) {
return;
}
- if (queries_out_ > 0) {
- return;
- }
+
delete this;
}
// This function is used as callback from DNSQuery.
virtual void operator()(IOFetch::Result result) {
// XXX is this the place for TCP retry?
- --queries_out_;
- if (!done_ && result != IOFetch::TIME_OUT) {
+ if (result != IOFetch::TIME_OUT) {
// we got an answer
Message incoming(Message::PARSE);
InputBuffer ibuf(buffer_->getData(), buffer_->getLength());
incoming.fromWire(ibuf);
isc::resolve::copyResponseMessage(incoming, answer_message_);
- done_ = true;
stop(true);
- } else if (!done_ && retries_--) {
- // We timed out, but we have some retries, so send again
- dlog("Timeout, resending query");
- send();
} else {
- // out of retries, give up for now
+ // timeout, give up for now
stop(false);
}
}
@@ -732,25 +685,14 @@ RecursiveQuery::forward(ConstMessagePtr query_message,
answer_message->setOpcode(isc::dns::Opcode::QUERY());
ConstQuestionPtr question = *query_message->beginQuestion();
answer_message->addQuestion(*question);
-
- // First try to see if we have something cached in the messagecache
- dlog("Try out cache first (started by incoming event)");
- if (cache_.lookup(question->getName(), question->getType(),
- question->getClass(), *answer_message)) {
- dlog("Message found in cache, returning that");
- // TODO: err, should cache set rcode as well?
- answer_message->setRcode(Rcode::NOERROR());
- crs->success(answer_message);
- } else {
- dlog("Message not found in cache, starting forward query");
- // It will delete itself when it is done
- new ForwardQuery(io, query_message, answer_message,
- upstream_, buffer, crs, query_timeout_,
- client_timeout_, lookup_timeout_,
- retries_, cache_);
- }
-}
-
+ // implement the simplest forwarder, which will pass
+ // everything throught without interpretation, except
+ // QID, port number. The response will not be cached.
+ // It will delete itself when it is done
+ new UpstreamQuery(io, query_message, answer_message,
+ upstream_, buffer, crs, query_timeout_,
+ client_timeout_, lookup_timeout_);
+}
} // namespace asiolink
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