int refresh_ip_table(void)
{
int err;
// Hold the iface table mutex while updating it
platform_mutex_acquire(&iface_table_mutex);
// Get all IPs for local interfaces
iface_table_len = MAX_IP_COUNT;
err = platform_iface_ip_table(iface_ip_table, &iface_table_len);
if (err != 0)
{
platform_mutex_release(&iface_table_mutex);
printf("Failed to get interface IP table\n");
return -1;
}
else
{
platform_mutex_release(&iface_table_mutex);
return 0;
}
}
void platform_client_release(void)
{
platform_mutex_release(&client_mutex);
}
int relay_loop(void)
{
char buffer[MDNS_MTU];
struct sockaddr_in src_addr, dst_addr, last_client_addr = { 0 };
int byte_count;
int src_length;
unsigned int i;
struct mdns_header *header = (struct mdns_header*)buffer;
memset(&dst_addr, 0, sizeof(dst_addr));
dst_addr.sin_family = AF_INET;
dst_addr.sin_port = htons(MDNS_PORT);
dst_addr.sin_addr.S_un.S_addr = htonl(MDNS_ADDR);
for (;;)
{
// Read a MDNS packet
src_length = sizeof(src_addr);
byte_count = recvfrom(mdns_socket, buffer, sizeof(buffer), 0, (struct sockaddr*)&src_addr, &src_length);
if (byte_count <= 0)
{
printf("Failed to receive packet (Error: %d)\n", platform_last_error());
return -1;
}
// Real MDNS is 5353 -> 5353
if (src_addr.sin_port == htons(MDNS_PORT))
{
// Acquire the mutex to protect the iface table
platform_mutex_acquire(&iface_table_mutex);
// Check if the source is a local link
for (i = 0; i < iface_table_len; i++)
{
if (src_addr.sin_addr.S_un.S_addr == iface_ip_table[i])
{
// This needs to go to the client
dst_addr = last_client_addr;
break;
}
}
// If it came in from the multicast group
// and it's not from a local source, it's other
// multicast traffic which we ignore.
if (i == iface_table_len)
{
platform_mutex_release(&iface_table_mutex);
continue;
}
else
{
platform_mutex_release(&iface_table_mutex);
}
}
else
{
// This looks like it came from the other relay
dst_addr.sin_addr.S_un.S_addr = htonl(MDNS_ADDR);
dst_addr.sin_port = htons(MDNS_PORT);
// Remember the source for next time
if (last_client_addr.sin_addr.S_un.S_addr != src_addr.sin_addr.S_un.S_addr ||
last_client_addr.sin_port != src_addr.sin_port)
{
last_client_addr = src_addr;
printf("Relaying MDNS traffic to %s:%d\n", inet_ntoa(src_addr.sin_addr), htons(src_addr.sin_port));
}
}
byte_count = sendto(mdns_socket, buffer, byte_count, 0, (struct sockaddr*)&dst_addr, sizeof(dst_addr));
if (byte_count <= 0)
{
printf("Failed to send packet (Error: %d)\n", platform_last_error());
return -1;
}
}
}
