linux man page for ipq_read

IPQ_READ(3)						     Linux Programmer's Manual						       IPQ_READ(3)

NAME
       ipq_read -- read queue messages from ip_queue and read into supplied buffer

SYNOPSIS
       #include <linux/netfilter.h>
       #include <libipq.h>

       ssize_t ipq_read(const struct ipq_handle *h, unsigned char *buf, size_t len, int timeout);

DESCRIPTION
       The ipq_read function reads a queue message from the kernel and copies it to the memory pointed to by buf to a maximum length of len.

       The h parameter is a context handle which must previously have been returned successfully from a call to ipq_create_handle.

       The caller is responsible for ensuring that the memory pointed to by buf is large enough to contain len bytes.

       The  timeout  parameter	may  be used to set a timeout for the operation, specified in microseconds.  This is implemented internally by the
       library via the select system call.  A value of zero provides normal, backwards-compatible blocking behaviour with no timeout.  A  negative
       value causes the function to return immediately.

       Data  returned  via  buf should not be accessed directly.  Use the ipq_message_type, ipq_get_packet, and ipq_get_msgerr functions to access
       the queue message in the buffer.

RETURN VALUE
       On failure, -1 is returned.
       On success, a non-zero positive value is returned when no timeout value is specified.
       On success with a timeout value specified, zero is returned if no data was available to read, or if a non-blocked signal  was  caught.	In
       the latter case, the global errno value will be set to EINTR.

ERRORS
       On error, a descriptive error message will be available via the ipq_errstr function.

DIAGNOSTICS
       While  the  ipq_read  function may return successfully, the queue message copied to the buffer may itself be an error message from a higher
       level kernel component.	Use ipq_message_type to determine if it is an error message, and ipq_get_msgerr to access the value  of  the  mes-
       sage.

BUGS
       None known.

AUTHOR
       James Morris <jmorris@intercode.com.au>

COPYRIGHT
       Copyright (c) 2000-2001 Netfilter Core Team.

       Distributed under the GNU General Public License.

CREDITS
       Joost Remijn implemented the timeout feature, which appeared in the 1.2.4 release of iptables.

SEE ALSO
       iptables(8), libipq(3), select(2).

Linux iptables 1.2						  16 October 2001						       IPQ_READ(3)