ipq_read(3)

1IPQ_READ(3)                Linux Programmer's Manual               IPQ_READ(3)
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NAME

6       ipq_read  —  read  queue  messages from ip_queue and read into supplied
7       buffer
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SYNOPSIS

10       #include <linux/netfilter.h>
11       #include <libipq.h>
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13       ssize_t ipq_read(const struct ipq_handle *h, unsigned char *buf, size_t
14       len, int timeout);
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DESCRIPTION

17       The  ipq_read function reads a queue message from the kernel and copies
18       it to the memory pointed to by buf to a maximum length of len.
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20       The h parameter is a context handle which  must  previously  have  been
21       returned successfully from a call to ipq_create_handle.
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23       The  caller  is  responsible for ensuring that the memory pointed to by
24       buf is large enough to contain len bytes.
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26       The timeout parameter may be used to set a timeout for  the  operation,
27       specified  in  microseconds.   This  is  implemented  internally by the
28       library via the select system call.  A value of zero  provides  normal,
29       backwards-compatible  blocking  behaviour  with no timeout.  A negative
30       value causes the function to return immediately.
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32       Data returned via  buf  should  not  be  accessed  directly.   Use  the
33       ipq_message_type,   ipq_get_packet,  and  ipq_get_msgerr  functions  to
34       access the queue message in the buffer.
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RETURN VALUE

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

45       On  error,  a  descriptive  error  message  will  be  available via the
46       ipq_errstr function.
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DIAGNOSTICS

49       While the ipq_read function may return successfully, the queue  message
50       copied to the buffer may itself be an error message from a higher level
51       kernel component.  Use ipq_message_type to determine if it is an  error
52       message, and ipq_get_msgerr to access the value of the message.
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BUGS

55       None known.
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AUTHOR

58       James Morris <jmorris@intercode.com.au>
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COPYRIGHT

61       Copyright (c) 2000-2001 Netfilter Core Team.
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63       Distributed under the GNU General Public License.
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CREDITS

66       Joost  Remijn  implemented  the  timeout feature, which appeared in the
67       1.2.4 release of iptables.
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