Throw GAIException() for getaddrinfo errors

Created a new subclass of Exception called GAIException() that will
handle error messages from getaddrinfo() instead of letting Exception()
handle it. GAIException() will make use of gai_strerror() to map the
error code to text. On Windows, gai_strerrorW() must be used if the text
is encoded with UTF-8.

common/network/TcpSocket.cxx

@@ -151,8 +151,7 @@ TcpSocket::TcpSocket(const char *host, int port)
   hints.ai_next = NULL;
 
   if ((result = getaddrinfo(host, NULL, &hints, &ai)) != 0) {
-    throw Exception("unable to resolve host by name: %s",
+    throw GAIException("unable to resolve host by name", result);
-                    gai_strerror(result));
   }
 
   sock = -1;
@@ -603,8 +602,7 @@ void network::createTcpListeners(std::list<SocketListener*> *listeners,
   snprintf (service, sizeof (service) - 1, "%d", port);
   service[sizeof (service) - 1] = '\0';
   if ((result = getaddrinfo(addr, service, &hints, &ai)) != 0)
-    throw rdr::Exception("unable to resolve listening address: %s",
+    throw GAIException("unable to resolve listening address", result);
-                         gai_strerror(result));
 
   try {
     createTcpListeners(listeners, ai);
@@ -913,8 +911,7 @@ TcpFilter::Pattern TcpFilter::parsePattern(const char* p) {
     }
 
     if ((result = getaddrinfo (p, NULL, &hints, &ai)) != 0) {
-      throw Exception("unable to resolve host by name: %s",
+      throw GAIException("unable to resolve host by name", result);
-                      gai_strerror(result));
     }
 
     memcpy (&pattern.address.u.sa, ai->ai_addr, ai->ai_addrlen);

common/rdr/Exception.cxx

@@ -31,6 +31,9 @@
 #include <tchar.h>
 #include <winsock2.h>
 #include <windows.h>
+#include <ws2tcpip.h>
+#else
+#include <netdb.h>
 #endif
 
 #include <string.h>
@@ -49,6 +52,21 @@ Exception::Exception(const char *format, ...) {
 	va_end(ap);
 }
 
+GAIException::GAIException(const char* s, int err)
+  : Exception("%s", s)
+{
+  strncat(str_, ": ", len-1-strlen(str_));
+#ifdef _WIN32
+  wchar_t currStr[len-strlen(str_)];
+  wcsncpy(currStr, gai_strerrorW(err), len-1-strlen(str_));
+  WideCharToMultiByte(CP_UTF8, 0, currStr, -1, str_+strlen(str_),
+                      len-1-strlen(str_), 0, 0);
+#else
+  //FIXME: perhaps print the error number (NNNN)
+  strncat(str_, gai_strerror(err), len-1-strlen(str_));
+#endif
+}
+
 SystemException::SystemException(const char* s, int err_)
   : Exception("%s", s), err(err_)
 {

common/rdr/Exception.h

@@ -42,6 +42,11 @@ namespace rdr {
     SystemException(const char* s, int err_);
   };
 
+  struct GAIException : public Exception {
+    int err;
+    GAIException(const char* s, int err_);
+  };
+
   struct TimedOut : public Exception {
     TimedOut() : Exception("Timed out") {}
   };