Avoids buffer overflow in xmlrpcpp if fd > 1024

A temporary fix to avoid buffer overflow in XmlRpcDispatch, since select() only works for file descriptors < FD_SETSIZE (1024). The real solution is to switch to poll as in #833, but since that PR was reverted, this avoids catastrophic failure. It throws instead of being silent, since (a) this behaviour is no less intrusive than a buffer overflow, and (b) returning an error was handled silently, and just looked like ros comm not being connected.

utilities/xmlrpcpp/src/XmlRpcDispatch.cpp

@@ -6,6 +6,7 @@
 #include <math.h>
 #include <errno.h>
 #include <sys/timeb.h>
+#include <stdexcept>
 #if defined (__ANDROID__)
 #include <sys/select.h>
 #endif
@@ -95,6 +96,10 @@ XmlRpcDispatch::work(double timeout)
  SourceList::iterator it;
  for (it=_sources.begin(); it!=_sources.end(); ++it) {
  int fd = it->getSource()->getfd();
+ if (fd >= FD_SETSIZE) {
+ _inWork = false;
+ throw std::runtime_error("XmlRpcDispatch::work: fd >= FD_SETSIZE limit, too many open files.");
+ }
  if (it->getMask() & ReadableEvent) FD_SET(fd, &inFd);
  if (it->getMask() & WritableEvent) FD_SET(fd, &outFd);
  if (it->getMask() & Exception) FD_SET(fd, &excFd);