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Remove broadcast-based local discovery mechanism.

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The new local address based local discovery mechanism is technically
superior to the old broadcast-based one. In fact, the old algorithm
can technically make things worse by e.g. sending broadcasts over the
VPN itself and then selecting the VPN address as the node's UDP
address. This cannot happen with the new mechanism.

Note that this means old nodes that don't send their local addresses in
ADD_EDGE messages can't be discovered, because there is no address to
send discovery packets to. Old nodes can still discover new nodes by
sending them broadcasts, though.
This commit is contained in:
Etienne Dechamps 2014-06-29 11:01:24 +01:00
parent e16ade874d
commit 4159108971
4 changed files with 5 additions and 58 deletions
Download patch file Download diff file Expand all files Collapse all files

1
src/net.h
View file

@ -126,7 +126,6 @@ extern int seconds_till_retry;
extern int addressfamily;
extern unsigned replaywin;
extern bool localdiscovery;
extern sockaddr_t localdiscovery_address;
extern listen_socket_t listen_socket[MAXSOCKETS];
extern int listen_sockets;

47
src/net_packet.c
View file

@ -55,7 +55,6 @@ static void send_udppacket(node_t *, vpn_packet_t *);
unsigned replaywin = 16;
bool localdiscovery = false;
sockaddr_t localdiscovery_address;
#define MAX_SEQNO 1073741824
@ -598,6 +597,8 @@ static void choose_udp_address(const node_t *n, const sockaddr_t **sa, int *sock
}
static void choose_local_address(const node_t *n, const sockaddr_t **sa, int *sock) {
*sa = NULL;
/* Pick one of the edges from this node at random, then use its local address. */
int i = 0;
@ -615,46 +616,6 @@ static void choose_local_address(const node_t *n, const sockaddr_t **sa, int *so
*sa = &candidate->local_address;
*sock = rand() % listen_sockets;
adapt_socket(*sa, sock);
return;
}
/* No candidate? Use broadcasts instead. */
static sockaddr_t broadcast_ipv4 = {
.in = {
.sin_family = AF_INET,
.sin_addr.s_addr = -1,
}
};
static sockaddr_t broadcast_ipv6 = {
.in6 = {
.sin6_family = AF_INET6,
.sin6_addr.s6_addr[0x0] = 0xff,
.sin6_addr.s6_addr[0x1] = 0x02,
.sin6_addr.s6_addr[0xf] = 0x01,
}
};
*sock = rand() % listen_sockets;
if(listen_socket[*sock].sa.sa.sa_family == AF_INET6) {
if(localdiscovery_address.sa.sa_family == AF_INET6) {
localdiscovery_address.in6.sin6_port = n->prevedge->address.in.sin_port;
*sa = &localdiscovery_address;
} else {
broadcast_ipv6.in6.sin6_port = n->prevedge->address.in.sin_port;
broadcast_ipv6.in6.sin6_scope_id = listen_socket[*sock].sa.in6.sin6_scope_id;
*sa = &broadcast_ipv6;
}
} else {
if(localdiscovery_address.sa.sa_family == AF_INET) {
localdiscovery_address.in.sin_port = n->prevedge->address.in.sin_port;
*sa = &localdiscovery_address;
} else {
broadcast_ipv4.in.sin_port = n->prevedge->address.in.sin_port;
*sa = &broadcast_ipv4;
}
}
}
@ -756,12 +717,12 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
/* Send the packet */
const sockaddr_t *sa;
const sockaddr_t *sa = NULL;
int sock;
if(n->status.send_locally)
choose_local_address(n, &sa, &sock);
else
if(!sa)
choose_udp_address(n, &sa, &sock);
#if defined(SOL_IP) && defined(IP_TOS)

10
src/net_setup.c
View file

@ -532,16 +532,6 @@ bool setup_myself_reloadable(void) {
get_config_bool(lookup_config(config_tree, "DirectOnly"), &directonly);
get_config_bool(lookup_config(config_tree, "LocalDiscovery"), &localdiscovery);
memset(&localdiscovery_address, 0, sizeof localdiscovery_address);
if(get_config_string(lookup_config(config_tree, "LocalDiscoveryAddress"), &address)) {
struct addrinfo *ai = str2addrinfo(address, myport, SOCK_DGRAM);
free(address);
if(!ai)
return false;
memcpy(&localdiscovery_address, ai->ai_addr, ai->ai_addrlen);
}
if(get_config_string(lookup_config(config_tree, "Mode"), &rmode)) {
if(!strcasecmp(rmode, "router"))
routing_mode = RMODE_ROUTER;