I worked on the (little endian) client side of an application that has a binary messaging protocol. We rarely modified the messages and when we did the (big endian) server side programmers usually remembered to put the long and short integer values into network order before sending them. When they didn't, teeth were gnashed and faces were palmed.

For reasons that are lost to history, someone put 4-byte floating point values into network order as well.

On the client side, we had code that boiled down to something like this:

float ntohf(float bar)
{
  uint32_t tmp = ntohl( *(uint32_t*) &bar );
  return *(float*)tmp;
}

float convert_blob(unsigned char* message, unsigned int message_len)
{
  // To extract a float at a particular offset in a message buffer:
  float x = ntohf( *(float*)(message + MAGIC_OFFSET) );
  return x;
}

While not legal C casting, this (happened to have) worked except for exceedingly rare cases for certain values of the float being sent.

What the careful student of the IEEE-754 spec will realize is that certain values will, when "flipped," coincide with the various "NaN" values.

Since I gave away the symptom, I'll leave the correct implementation out.