incubator-nuttx/Documentation/components/net/pkt.rst

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===========================
"Raw" packet socket support
===========================
Packet sockets (:c:macro:`AF_PACKET`) allow receiving and transmitting frames
without a transport protocol in between. Frames received are copied into a
packet socket tap before they enter the network. Data written into a packet
socket will bypass the network altogether and be placed in the transmission
buffer of the network interface driver.
Configuration Options
=====================
``CONFIG_NET_PKT_PREALLOC_CONNS``
Number of preallocated packet connections (all tasks).
``CONFIG_NET_PKT_ALLOC_CONNS``
Dynamic memory allocations for packet connections.
``CONFIG_NET_PKT_MAX_CONNS``
Maximum number of packet connections.
Usage
=====
.. code-block:: c
struct sockaddr_ll addr;
uint8_t buffer[BUFSIZE];
int sd = socket(AF_PACKET, SOCK_RAW, 0); /* Create a packet socket */
addr.sll_family = AF_PACKET;
addr.sll_ifindex = if_nametoindex("eth0");
bind(sd, (FAR struct sockaddr *)&addr, sizeof(addr)); /* Bind to device */
recv(sd, buffer, sizeof(buffer), 0); /* read(sd, buffer, sizeof(buffer)); */
send(sd, buffer, sizeof(buffer), 0); /* write(sd, buffer, sizeof(buffer)); */
close(sd); /* Close the socket */