The flags argument to
recv is a bit
mask. You can bitwise-OR the values of the following macros together
to obtain a value for this argument. All are defined in the header
Send or receive out-of-band data. See Out-of-Band Data.
Look at the data but don’t remove it from the input queue. This is
only meaningful with input functions such as
recv, not with
Don’t include routing information in the message. This is only meaningful with output operations, and is usually only of interest for diagnostic or routing programs. We don’t try to explain it here.