err_t ether_output(struct netif *netif, struct pbuf *p, struct ip_addr *ipaddr) {
struct pbuf *q;
struct eth_hdr *ethhdr;
struct eth_addr *dest, mcastaddr;
struct ip_addr *queryaddr;
err_t err;
int i;
int loopback = 0;
//kprintf("ether: xmit %d bytes, %d bufs\n", p->tot_len, pbuf_clen(p));
if ((netif->flags & NETIF_UP) == 0) return -ENETDOWN;
if (pbuf_header(p, ETHER_HLEN)) {
kprintf(KERN_ERR "ether_output: not enough room for Ethernet header in pbuf\n");
stats.link.err++;
return -EBUF;
}
// Construct Ethernet header. Start with looking up deciding which
// MAC address to use as a destination address. Broadcasts and
// multicasts are special, all other addresses are looked up in the
// ARP table.
queryaddr = ipaddr;
if (ip_addr_isany(ipaddr) || ip_addr_isbroadcast(ipaddr, &netif->netmask)) {
dest = (struct eth_addr *) ðbroadcast;
} else if (ip_addr_ismulticast(ipaddr)) {
// Hash IP multicast address to MAC address.
mcastaddr.addr[0] = 0x01;
mcastaddr.addr[1] = 0x0;
mcastaddr.addr[2] = 0x5e;
mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
mcastaddr.addr[4] = ip4_addr3(ipaddr);
mcastaddr.addr[5] = ip4_addr4(ipaddr);
dest = &mcastaddr;
} else if (ip_addr_cmp(ipaddr, &netif->ipaddr)) {
dest = &netif->hwaddr;
loopback = 1;
} else {
if (ip_addr_maskcmp(ipaddr, &netif->ipaddr, &netif->netmask)) {
// Use destination IP address if the destination is on the same subnet as we are.
queryaddr = ipaddr;
} else {
// Otherwise we use the default router as the address to send the Ethernet frame to.
queryaddr = &netif->gw;
}
dest = arp_lookup(queryaddr);
}
// If the arp_lookup() didn't find an address, we send out an ARP query for the IP address.
if (dest == NULL) {
q = arp_query(netif, &netif->hwaddr, queryaddr);
if (q != NULL) {
err = dev_transmit((dev_t) netif->state, q);
if (err < 0) {
kprintf(KERN_ERR "ether: error %d sending arp packet\n", err);
pbuf_free(q);
stats.link.drop++;
return err;
}
}
// Queue packet for transmission, when the ARP reply returns
err = arp_queue(netif, p, queryaddr);
if (err < 0) {
kprintf(KERN_ERR "ether: error %d queueing packet\n", err);
stats.link.drop++;
stats.link.memerr++;
return err;
}
return 0;
}
ethhdr = p->payload;
for (i = 0; i < 6; i++) {
ethhdr->dest.addr[i] = dest->addr[i];
ethhdr->src.addr[i] = netif->hwaddr.addr[i];
}
ethhdr->type = htons(ETHTYPE_IP);
if (loopback) {
struct pbuf *q;
q = pbuf_dup(PBUF_RAW, p);
if (!q) return -ENOMEM;
err = ether_input(netif, q);
if (err < 0) {
pbuf_free(q);
return err;
}
} else {
err = dev_transmit((dev_t) netif->state, p);
if (err < 0) {
kprintf(KERN_ERR "ether: error %d sending packet\n", err);
return err;
}
}
return 0;
}
/*-----------------------------------------------------------------------------------*/
static err_t
tapif_output(struct netif *netif, struct pbuf *p,
struct ip_addr *ipaddr)
{
struct tapif *tapif;
struct pbuf *q;
struct eth_hdr *ethhdr;
struct eth_addr *dest, mcastaddr;
struct ip_addr *queryaddr;
err_t err;
u8_t i;
tapif = netif->state;
/* Make room for Ethernet header. */
if(pbuf_header(p, sizeof(struct eth_hdr)) != 0) {
/* The pbuf_header() call shouldn't fail, but we allocate an extra
pbuf just in case. */
q = pbuf_alloc(PBUF_LINK, sizeof(struct eth_hdr), PBUF_RAM);
if(q == NULL) {
return ERR_MEM;
}
pbuf_chain(q, p);
p = q;
}
/* Construct Ethernet header. Start with looking up deciding which
MAC address to use as a destination address. Broadcasts and
multicasts are special, all other addresses are looked up in the
ARP table. */
queryaddr = ipaddr;
if(ip_addr_isany(ipaddr) ||
ip_addr_isbroadcast(ipaddr, &(netif->netmask))) {
dest = (struct eth_addr *)ðbroadcast;
} else if(ip_addr_ismulticast(ipaddr)) {
/* Hash IP multicast address to MAC address. */
mcastaddr.addr[0] = 0x01;
mcastaddr.addr[1] = 0x0;
mcastaddr.addr[2] = 0x5e;
mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
mcastaddr.addr[4] = ip4_addr3(ipaddr);
mcastaddr.addr[5] = ip4_addr4(ipaddr);
dest = &mcastaddr;
} else {
if(ip_addr_maskcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
/* Use destination IP address if the destination is on the same
subnet as we are. */
queryaddr = ipaddr;
} else {
/* Otherwise we use the default router as the address to send
the Ethernet frame to. */
queryaddr = &(netif->gw);
}
dest = arp_lookup(queryaddr);
}
/* If the arp_lookup() didn't find an address, we send out an ARP
query for the IP address. */
if(dest == NULL) {
q = arp_query(netif, tapif->ethaddr, queryaddr);
if(q != NULL) {
printf("Sending ARP after query\n");
err = low_level_output(tapif, q);
pbuf_free(q);
return err;
}
return ERR_MEM;
}
ethhdr = p->payload;
for(i = 0; i < 6; i++) {
ethhdr->dest.addr[i] = dest->addr[i];
ethhdr->src.addr[i] = tapif->ethaddr->addr[i];
}
ethhdr->type = htons(ETHTYPE_IP);
return low_level_output(tapif, p);
}
