PCAP_INJECT(3PCAP) PCAP_INJECT(3PCAP)
NAME
pcap_inject, pcap_sendpacket - transmit a packet
SYNOPSIS
#include <pcap/pcap.h>
int pcap_inject(pcap_t *p, const void *buf, size_t size);
int pcap_sendpacket(pcap_t *p, const u_char *buf, int size);
DESCRIPTION
pcap_inject() sends a raw packet through the network interface; buf
points to the data of the packet, including the link-layer header, and
size is the number of bytes in the packet.
Note that, even if you successfully open the network interface, you
might not have permission to send packets on it, or it might not sup-
port sending packets; as pcap_open_live(3PCAP) doesn't have a flag to
indicate whether to open for capturing, sending, or capturing and send-
ing, you cannot request an open that supports sending and be notified
at open time whether sending will be possible. Note also that some de-
vices might not support sending packets.
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 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 do nominally support sending completely raw and un-
changed packets.
pcap_sendpacket() is like pcap_inject(), but it returns 0 on success,
rather than returning the number of bytes written. (pcap_inject()
comes from OpenBSD; pcap_sendpacket() comes from WinPcap/Npcap. Both
are provided for compatibility.)
RETURN VALUE
pcap_inject() returns the number of bytes written on success, PCAP_ER-
ROR_NOT_ACTIVATED if called on a capture handle that has been created
but not activated, and PCAP_ERROR on other errors.
pcap_sendpacket() returns 0 on success, PCAP_ERROR_NOT_ACTIVATED if
called on a capture handle that has been created but not activated, and
PCAP_ERROR on other errors.
If PCAP_ERROR is returned, pcap_geterr(3PCAP) or pcap_perror(3PCAP) may
be called with p as an argument to fetch or display the error text.
SEE ALSO
pcap(3PCAP)
5 March 2022 PCAP_INJECT(3PCAP)
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