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Add LocalDiscovery option which tries to detect peers on the local network.

Browse source 
Currently, this is implemented by sending IPv4 broadcast packets to the
LAN during path MTU discovery.
This commit is contained in:
Guus Sliepen 2012-02-22 23:17:43 +01:00
parent 8e717ddb60
commit 5a28aa7b8b
8 changed files with 67 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

46
src/net_packet.c
View file

@ -61,13 +61,21 @@ static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999
static void send_udppacket(node_t *, vpn_packet_t *);
unsigned replaywin = 16;
bool localdiscovery = false;
#define MAX_SEQNO 1073741824
// mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
// mtuprobes == 31: sleep pinginterval seconds
// mtuprobes == 32: send 1 burst, sleep pingtimeout second
// mtuprobes == 33: no response from other side, restart PMTU discovery process
/* mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
mtuprobes == 31: sleep pinginterval seconds
mtuprobes == 32: send 1 burst, sleep pingtimeout second
mtuprobes == 33: no response from other side, restart PMTU discovery process
Probes are sent in batches of three, with random sizes between the lower and
upper boundaries for the MTU thus far discovered.
In case local discovery is enabled, a fourth packet is added to each batch,
which will be broadcast to the local network.
*/
void send_mtu_probe(node_t *n) {
vpn_packet_t packet;
@ -118,7 +126,7 @@ void send_mtu_probe(node_t *n) {
timeout = pingtimeout;
}
for(i = 0; i < 3; i++) {
for(i = 0; i < 3 + localdiscovery; i++) {
if(n->maxmtu <= n->minmtu)
len = n->maxmtu;
else
@ -130,7 +138,7 @@ void send_mtu_probe(node_t *n) {
memset(packet.data, 0, 14);
RAND_pseudo_bytes(packet.data + 14, len - 14);
packet.len = len;
packet.priority = 0;
packet.priority = i < 3 ? 0 : -1;
ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
@ -486,6 +494,29 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
/* Send the packet */
struct sockaddr *sa;
socklen_t sl;
int sock;
/* Overloaded use of priority field: -1 means local broadcast */
if(origpriority == -1 && n->prevedge) {
struct sockaddr_in in;
in.sin_family = AF_INET;
in.sin_addr.s_addr = -1;
in.sin_port = n->prevedge->address.in.sin_port;
sa = (struct sockaddr *)&in;
sl = sizeof in;
sock = 0;
} else {
if(origpriority == -1)
origpriority = 0;
sa = &(n->address.sa);
sl = SALEN(n->address.sa);
sock = n->sock;
}
#if defined(SOL_IP) && defined(IP_TOS)
if(priorityinheritance && origpriority != priority
&& listen_socket[n->sock].sa.sa.sa_family == AF_INET) {
@ -496,7 +527,7 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
}
#endif
if(sendto(listen_socket[n->sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) {
if(sockmsgsize(sockerrno)) {
if(n->maxmtu >= origlen)
n->maxmtu = origlen - 1;
@ -600,6 +631,7 @@ static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
if(hard)
last_hard_try = now;
last_hard_try = now;
return n;
}