PCAP_INJECT(3)         FreeBSD Library Functions Manual         PCAP_INJECT(3)

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 support
     sending packets; as pcap_open_live(3) 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.

     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
     unchanged 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_ERROR_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(3) or pcap_perror(3) may be called
     with p as an argument to fetch or display the error text.

SEE ALSO

     pcap(3)

                                 5 March 2022                   PCAP_INJECT(3)