NAME

SYNOPSIS

int ipq_message_type(const unsigned char *buf);
ipq_packet_msg_t *ipq_get_packet(const unsigned char *buf);
int ipq_get_msgerr(const unsigned char *buf);  

DESCRIPTION

ipq_message_type should always be called following a successful call to ipq_read to determine whether the message is a packet message or an error message. The buf parameter should be the same data obtained from the previous call to ipq_read.

ipq_message_type will return one of the following values:

NLMSG_ERROR

An error message generated by the Netlink transport.

IPQM_PACKET

A packet message containing packet metadata and optional packet payload data.

The ipq_get_packet function should be called if ipq_message_type returns IPQM_PACKET. The buf parameter should point to the same data used for the call to ipq_message_type. The pointer returned by ipq_get_packet points to a packet message, which is declared as follows:

typedef struct ipq_packet_msg {
        unsigned long packet_id;        /* ID of queued packet */
        unsigned long mark;             /* Netfilter mark value */
        long timestamp_sec;             /* Packet arrival time (seconds) */
        long timestamp_usec;            /* Packet arrvial time (+useconds) */
        unsigned int hook;              /* Netfilter hook we rode in on */
        char indev_name[IFNAMSIZ];      /* Name of incoming interface */
        char outdev_name[IFNAMSIZ];     /* Name of outgoing interface */
        unsigned short hw_protocol;     /* Hardware protocol (network order) */
        unsigned short hw_type;         /* Hardware type */
        unsigned char hw_addrlen;       /* Hardware address length */
        unsigned char hw_addr[8];       /* Hardware address */
        size_t data_len;                /* Length of packet data */
        unsigned char payload[0];       /* Optional packet data */
} ipq_packet_msg_t;

Each of these fields may be read by the application. If the queue mode is IPQ_COPY_PACKET and the data_len value is greater than zero, the packet payload contents may be accessed in the memory following the ipq_packet_msg_t structure to a range of data_len.

The packet_id field contains a packet identifier to be used when calling ipq_set_verdict.

The ipq_get_msgerr function should be called if ipq_message_type returns NLMSG_ERROR. The buf parameter should point to the same data used for the call to ipq_message_type. The value returned by ipq_get_msgerr is set by higher level kernel code and corresponds to standard errno values.  

BUGS

AUTHOR

COPYRIGHT

Distributed under the GNU General Public License.  

SEE ALSO

Index

NAME

SYNOPSIS

DESCRIPTION

BUGS

AUTHOR

COPYRIGHT

SEE ALSO