GH #68: DNS::hostByAddress can be slow

GH #68: DNS::hostByAddress can be slow - added parameters in the
interface to pass hint flags to hostByAddress() and hostByName() calls

Net/include/Poco/Net/DNS.h

@@ -57,9 +57,31 @@ class Net_API DNS
 	/// An internal DNS cache is used to speed up name lookups.
 {
 public:
-	static HostEntry hostByName(const std::string& hostname);
+
+	enum HintFlag
+	{
+		DNS_HINT_NONE = 0,
+#ifdef POCO_HAVE_ADDRINFO
+		DNS_HINT_AI_PASSIVE = AI_PASSIVE,  // Socket address will be used in bind() call
+		DNS_HINT_AI_CANONNAME = AI_CANONNAME, // Return canonical name in first ai_canonname
+		DNS_HINT_AI_NUMERICHOST = AI_NUMERICHOST, // Nodename must be a numeric address string
+		DNS_HINT_AI_NUMERICSERV = AI_NUMERICSERV, // Servicename must be a numeric port number
+		DNS_HINT_AI_ALL = AI_ALL, // Query both IP6 and IP4 with AI_V4MAPPED
+		DNS_HINT_AI_ADDRCONFIG = AI_ADDRCONFIG, // Resolution only if global address configured
+		DNS_HINT_AI_V4MAPPED = AI_V4MAPPED, // On v6 failure, query v4 and convert to V4MAPPED format	
+#endif
+	};
+
+	static HostEntry hostByName(const std::string& hostname, unsigned hintFlags =
+#ifdef POCO_HAVE_ADDRINFO
+		DNS_HINT_AI_CANONNAME | DNS_HINT_AI_ADDRCONFIG
+#else
+		DNS_HINT_NONE
+#endif		
+		);
 		/// Returns a HostEntry object containing the DNS information
-		/// for the host with the given name.
+		/// for the host with the given name. HintFlag argument is only
+		/// used on platforms that have getaddrinfo().
 		///
 		/// Throws a HostNotFoundException if a host with the given
 		/// name cannot be found.
@@ -71,9 +93,16 @@ public:
 		///
 		/// Throws an IOException in case of any other error.
 		
-	static HostEntry hostByAddress(const IPAddress& address);
+	static HostEntry hostByAddress(const IPAddress& address, unsigned hintFlags =
+#ifdef POCO_HAVE_ADDRINFO
+		DNS_HINT_AI_CANONNAME | DNS_HINT_AI_ADDRCONFIG
+#else
+		DNS_HINT_NONE
+#endif		
+		);
 		/// Returns a HostEntry object containing the DNS information
-		/// for the host with the given IP address.
+		/// for the host with the given IP address. HintFlag argument is only
+		/// used on platforms that have getaddrinfo().
 		///
 		/// Throws a HostNotFoundException if a host with the given
 		/// name cannot be found.

Net/src/DNS.cpp

@@ -62,17 +62,21 @@ static Poco::RWLock resolverLock;
 #endif
 
 
-HostEntry DNS::hostByName(const std::string& hostname)
+HostEntry DNS::hostByName(const std::string& hostname, unsigned 
+#ifdef POCO_HAVE_ADDRINFO
+						  hintFlags
+#endif
+						 )
 {
 #if defined(POCO_HAVE_LIBRESOLV)
 	Poco::ScopedReadRWLock readLock(resolverLock);
 #endif
 	
-#if defined(POCO_HAVE_IPv6) || defined(POCO_HAVE_ADDRINFO)
+#if defined(POCO_HAVE_ADDRINFO)
 	struct addrinfo* pAI;
 	struct addrinfo hints;
 	std::memset(&hints, 0, sizeof(hints));
-	hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
+	hints.ai_flags = hintFlags;
 	int rc = getaddrinfo(hostname.c_str(), NULL, &hints, &pAI); 
 	if (rc == 0)
 	{
@@ -102,13 +106,17 @@ HostEntry DNS::hostByName(const std::string& hostname)
 }
 
 
-HostEntry DNS::hostByAddress(const IPAddress& address)
+HostEntry DNS::hostByAddress(const IPAddress& address, unsigned 
+#ifdef POCO_HAVE_ADDRINFO
+							 hintFlags
+#endif
+							)
 {
 #if defined(POCO_HAVE_LIBRESOLV)
 	Poco::ScopedReadRWLock readLock(resolverLock);
 #endif
 
-#if defined(POCO_HAVE_IPv6) || defined(POCO_HAVE_ADDRINFO)
+#if defined(POCO_HAVE_ADDRINFO)
 	SocketAddress sa(address, 0);
 	static char fqname[1024];
 	int rc = getnameinfo(sa.addr(), sa.length(), fqname, sizeof(fqname), NULL, 0, NI_NAMEREQD); 
@@ -117,7 +125,7 @@ HostEntry DNS::hostByAddress(const IPAddress& address)
 		struct addrinfo* pAI;
 		struct addrinfo hints;
 		std::memset(&hints, 0, sizeof(hints));
-		hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
+		hints.ai_flags = hintFlags;
 		rc = getaddrinfo(fqname, NULL, &hints, &pAI);
 		if (rc == 0)
 		{
@@ -148,7 +156,7 @@ HostEntry DNS::hostByAddress(const IPAddress& address)
 	}
 #endif
 	int err = lastError();
-	error(err, address.toString());      // will throw an appropriate exception
+	error(err, address.toString()); // will throw an appropriate exception
 	throw NetException(); // to silence compiler
 }
 

Net/testsuite/src/HTTPClientSessionTest.cpp

@@ -167,13 +167,15 @@ void HTTPClientSessionTest::testPostLargeChunked()
 	HTTPRequest request(HTTPRequest::HTTP_POST, "/echo");
 	std::string body(16000, 'x');
 	request.setChunkedTransferEncoding(true);
-	s.sendRequest(request) << body;
+	std::ostream& os = s.sendRequest(request);
+	os << body;
+	os.flush();
 	HTTPResponse response;
 	std::istream& rs = s.receiveResponse(response);
 	assert (response.getChunkedTransferEncoding());
 	assert (response.getContentLength() == HTTPMessage::UNKNOWN_CONTENT_LENGTH);
 	std::ostringstream ostr;
-	StreamCopier::copyStream(rs, ostr);
+	StreamCopier::copyStream(rs, ostr, 16000);
 	assert (ostr.str() == body);
 }