void arp_out(FAR struct net_driver_s *dev)
{
struct ether_addr ethaddr;
FAR struct eth_hdr_s *peth = ETHBUF;
FAR struct arp_iphdr_s *pip = IPBUF;
in_addr_t ipaddr;
in_addr_t destipaddr;
int ret;
#if defined(CONFIG_NET_PKT) || defined(CONFIG_NET_ARP_SEND)
/* Skip sending ARP requests when the frame to be transmitted was
* written into a packet socket.
*/
if (IFF_IS_NOARP(dev->d_flags))
{
/* Clear the indication and let the packet continue on its way. */
IFF_CLR_NOARP(dev->d_flags);
return;
}
#endif
/* Find the destination IP address in the ARP table and construct
* the Ethernet header. If the destination IP address isn't on the
* local network, we use the default router's IP address instead.
*
* If not ARP table entry is found, we overwrite the original IP
* packet with an ARP request for the IP address.
*/
/* First check if destination is a local broadcast. */
if (net_ipv4addr_hdrcmp(pip->eh_destipaddr, g_broadcast_ipaddr))
{
memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
goto finish_header;
}
#ifdef CONFIG_NET_IGMP
/* Check if the destination address is a multicast address
*
* - IPv4: multicast addresses lie in the class D group -- The address range
* 224.0.0.0 to 239.255.255.255 (224.0.0.0/4)
*
* - IPv6 multicast addresses are have the high-order octet of the
* addresses=0xff (ff00::/8.)
*/
if (NTOHS(pip->eh_destipaddr[0]) >= 0xe000 &&
NTOHS(pip->eh_destipaddr[0]) <= 0xefff)
{
/* Build the well-known IPv4 IGMP Ethernet address. The first
* three bytes are fixed; the final three variable come from the
* last three bytes of the IPv4 address (network order).
*
* Address range : 01:00:5e:00:00:00 to 01:00:5e:7f:ff:ff
*/
FAR const uint8_t *ip = (FAR uint8_t *)pip->eh_destipaddr;
peth->dest[0] = g_multicast_ethaddr[0];
peth->dest[1] = g_multicast_ethaddr[1];
peth->dest[2] = g_multicast_ethaddr[2];
peth->dest[3] = ip[1] & 0x7f;
peth->dest[4] = ip[2];
peth->dest[5] = ip[3];
goto finish_header;
}
#endif
/* Check if the destination address is on the local network. */
destipaddr = net_ip4addr_conv32(pip->eh_destipaddr);
if (!net_ipv4addr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask))
{
/* Destination address is not on the local network */
#ifdef CONFIG_NET_ROUTE
/* We have a routing table.. find the correct router to use in
* this case (or, as a fall-back, use the device's default router
* address). We will use the router IP address instead of the
* destination address when determining the MAC address.
*/
netdev_ipv4_router(dev, destipaddr, &ipaddr);
#else
/* Use the device's default router IP address instead of the
* destination address when determining the MAC address.
*/
net_ipv4addr_copy(ipaddr, dev->d_draddr);
#endif
}
/* The destination address is on the local network. Check if it is
* the sub-net broadcast address.
*/
else if (net_ipv4addr_broadcast(destipaddr, dev->d_netmask))
{
/* Yes.. then we won't need to know the destination MAC address */
memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
goto finish_header;
}
else
{
/* Else, we use the destination IP address. */
net_ipv4addr_copy(ipaddr, destipaddr);
}
/* Check if we already have this destination address in the ARP table */
ret = arp_find(ipaddr, ðaddr);
if (ret < 0)
{
ninfo("ARP request for IP %08lx\n", (unsigned long)ipaddr);
/* The destination address was not in our ARP table, so we overwrite
* the IP packet with an ARP request.
*/
arp_format(dev, ipaddr);
arp_dump(ARPBUF);
return;
}
/* Build an Ethernet header. */
memcpy(peth->dest, ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
/* Finish populating the Ethernet header */
finish_header:
memcpy(peth->src, dev->d_mac.ether.ether_addr_octet, ETHER_ADDR_LEN);
peth->type = HTONS(ETHTYPE_IP);
dev->d_len += ETH_HDRLEN;
}
static uint8_t devif_reassembly(void)
{
FAR struct ipv4_hdr_s *pbuf = BUF;
FAR struct ipv4_hdr_s *pfbuf = FBUF;
uint16_t offset;
uint16_t len;
uint16_t i;
/* If g_reassembly_timer is zero, no packet is present in the buffer, so
* we write the IP header of the fragment into the reassembly buffer. The
* timer is updated with the maximum age.
*/
if (!g_reassembly_timer)
{
memcpy(g_reassembly_buffer, &pbuf->vhl, IPv4_HDRLEN);
g_reassembly_timer = CONFIG_NET_TCP_REASS_MAXAGE;
g_reassembly_flags = 0;
/* Clear the bitmap. */
memset(g_reassembly_bitmap, 0, sizeof(g_reassembly_bitmap));
}
/* Check if the incoming fragment matches the one currently present
* in the reassembly buffer. If so, we proceed with copying the
* fragment into the buffer.
*/
if (net_ipv4addr_hdrcmp(pbuf->srcipaddr, pfbuf->srcipaddr) &&
net_ipv4addr_hdrcmp(pbuf->destipaddr, pfbuf->destipaddr) &&
pbuf->g_ipid[0] == pfbuf->g_ipid[0] && pbuf->g_ipid[1] == pfbuf->g_ipid[1])
{
len = (pbuf->len[0] << 8) + pbuf->len[1] - (pbuf->vhl & 0x0f) * 4;
offset = (((pbuf->ipoffset[0] & 0x3f) << 8) + pbuf->ipoffset[1]) * 8;
/* If the offset or the offset + fragment length overflows the
* reassembly buffer, we discard the entire packet.
*/
if (offset > TCP_REASS_BUFSIZE || offset + len > TCP_REASS_BUFSIZE)
{
g_reassembly_timer = 0;
goto nullreturn;
}
/* Copy the fragment into the reassembly buffer, at the right offset. */
memcpy(&g_reassembly_buffer[IPv4_HDRLEN + offset], (char *)pbuf + (int)((pbuf->vhl & 0x0f) * 4), len);
/* Update the bitmap. */
if (offset / (8 * 8) == (offset + len) / (8 * 8))
{
/* If the two endpoints are in the same byte, we only update that byte. */
g_reassembly_bitmap[offset / (8 * 8)] |=
g_bitmap_bits[(offset / 8 ) & 7] & ~g_bitmap_bits[((offset + len) / 8 ) & 7];
}
else
{
/* If the two endpoints are in different bytes, we update the bytes
* in the endpoints and fill the stuff inbetween with 0xff.
*/
g_reassembly_bitmap[offset / (8 * 8)] |= g_bitmap_bits[(offset / 8 ) & 7];
for (i = 1 + offset / (8 * 8); i < (offset + len) / (8 * 8); ++i)
{
g_reassembly_bitmap[i] = 0xff;
}
g_reassembly_bitmap[(offset + len) / (8 * 8)] |=
~g_bitmap_bits[((offset + len) / 8 ) & 7];
}
/* If this fragment has the More Fragments flag set to zero, we know that
* this is the last fragment, so we can calculate the size of the entire
* packet. We also set the IP_REASS_FLAG_LASTFRAG flag to indicate that
* we have received the final fragment.
*/
if ((pbuf->ipoffset[0] & IP_MF) == 0)
{
g_reassembly_flags |= TCP_REASS_LASTFRAG;
g_reassembly_len = offset + len;
}
/* Finally, we check if we have a full packet in the buffer. We do this
* by checking if we have the last fragment and if all bits in the bitmap
* are set.
*/
if (g_reassembly_flags & TCP_REASS_LASTFRAG)
{
/* Check all bytes up to and including all but the last byte in
* the bitmap.
*/
for (i = 0; i < g_reassembly_len / (8 * 8) - 1; ++i)
{
if (g_reassembly_bitmap[i] != 0xff)
{
goto nullreturn;
}
}
/* Check the last byte in the bitmap. It should contain just the
* right amount of bits.
*/
if (g_reassembly_bitmap[g_reassembly_len / (8 * 8)] != (uint8_t)~g_bitmap_bits[g_reassembly_len / 8 & 7])
{
goto nullreturn;
}
/* If we have come this far, we have a full packet in the buffer,
* so we allocate a pbuf and copy the packet into it. We also reset
* the timer.
*/
g_reassembly_timer = 0;
memcpy(pbuf, pfbuf, g_reassembly_len);
/* Pretend to be a "normal" (i.e., not fragmented) IP packet from
* now on.
*/
pbuf->ipoffset[0] = pbuf->ipoffset[1] = 0;
pbuf->len[0] = g_reassembly_len >> 8;
pbuf->len[1] = g_reassembly_len & 0xff;
pbuf->ipchksum = 0;
pbuf->ipchksum = ~(ipv4_chksum(dev));
return g_reassembly_len;
}
}
