“Raw” packet socket support

Packet sockets (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.
CONFIG_NET_PKT_WRITE_BUFFERS: Use write buffers for packet sockets, support SOCK_NONBLOCK mode.
CONFIG_NET_PKTPROTO_OPTIONS: Enable setting protocol options on packet sockets.

Usage

struct sockaddr_ll addr;
uint8_t buffer[BUFSIZE];
int sd = socket(AF_PACKET, SOCK_RAW, 0); /* Create a Raw packet socket */

addr.sll_family = AF_PACKET;
addr.sll_ifindex = if_nametoindex("eth0");
addr.sll_protocol = htons(ETH_P_ALL);
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 */

struct sockaddr_ll addr;
uint8_t buffer[BUFSIZE];
int sd = socket(AF_PACKET, SOCK_DGRAM, 0); /* Create a Dgram packet socket */

addr.sll_family = AF_PACKET;
addr.sll_ifindex = if_nametoindex("eth0");
addr.sll_protocol = htons(ETH_P_IP);
bind(sd, (FAR struct sockaddr *)&addr, sizeof(addr)); /* Bind to device */

recv(sd, buffer, sizeof(buffer), 0); /* read(sd, buffer, sizeof(buffer)); */

memset(addr.sll_addr, 0xff, sizeof(addr.sll_addr)); /* Destination MAC address */
addr.sll_halen = ETH_ALEN;
sendto(sd, buffer, sizeof(buffer), 0, /* SOCK_DGRAM can not use write() */
       (struct sockaddr *)&addr, sizeof(addr));

close(sd); /* Close the socket */

int sd;
struct packet_mreq mreq;
char macaddr[ETH_ALEN] = {0x91, 0xe0, 0xf0, 0x00, 0x0e, 0x01};

sd = socket(AF_PACKET, SOCK_RAW, 0);

mreq.mr_ifindex = if_nametoindex("eth0");
mreq.mr_type = PACKET_MR_MULTICAST;
mreq.mr_alen = ETH_ALEN;
memcpy(&mreq.mr_address, macaddr, ETH_ALEN);

setsockopt(sd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq,
           sizeof(struct packet_mreq));

close(sd);