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.TH PCAP_INJECT 3PCAP "25 July 2018"

.SH NAME

pcap_inject, pcap_sendpacket \- transmit a packet

.SH SYNOPSIS

.nf

.ft B

#include <pcap/pcap.h>

.ft

.LP

.ft B

int pcap_inject(pcap_t *p, const void *buf, size_t size);

int pcap_sendpacket(pcap_t *p, const u_char *buf, int size);

.ft

.fi

.SH DESCRIPTION

.B pcap_inject()

sends a raw packet through the network interface;

.I buf

points to the data of the packet, including the link-layer header, and

.I size

is the number of bytes in the packet.

.PP

Note that, even if you successfully open the network interface, you

might not have permission to send packets on it, or it might not support

sending packets; as

.B pcap_open_live(3PCAP)

doesn't have a flag to indicate whether to open for capturing, sending,

or capturing and sending, you cannot request an open that supports

sending and be notified at open time whether sending will be possible.

Note also that some devices might not support sending packets.

.PP

Note that, on some platforms, the link-layer header of the packet that's

sent might not be the same as the link-layer header of the packet

supplied to

.BR pcap_inject() ,

as the source link-layer address, if the header contains such an

address, might be changed to be the address assigned to the interface on

which the packet it sent, if the platform doesn't support sending

completely raw and unchanged packets.  Even worse, some drivers on some

platforms might change the link-layer type field to whatever value

libpcap used when attaching to the device, even on platforms that

.I do

nominally support sending completely raw and unchanged packets.

.PP

.B pcap_sendpacket()

is like

.BR pcap_inject() ,

but it returns 0 on success, rather than returning the number of bytes

written.

.RB ( pcap_inject()

comes from OpenBSD;

.B pcap_sendpacket()

comes from WinPcap.  Both are provided for compatibility.)

.SH RETURN VALUE

.B pcap_inject()

returns the number of bytes written on success and

.B PCAP_ERROR

on failure.

.PP

.B pcap_sendpacket()

returns 0 on success and

.B PCAP_ERROR

on failure.

.PP

If

.B PCAP_ERROR

is returned,

.B pcap_geterr(3PCAP)

or

.B pcap_perror(3PCAP)

may be called with

.I p

as an argument to fetch or display the error text.

.SH SEE ALSO

pcap(3PCAP)