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allowed edge to optionally auto-detetct local IP address ('-e auto') for advertising as preferred (#776)

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Logan oos Even 2021-09-12 00:22:05 +05:45 committed by GitHub
parent defad50f87
commit 7f1fe9a499
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 43 additions and 20 deletions
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5
edge.8
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@ -44,10 +44,11 @@ TOS for packets, e.g. 0x48 for SSH like priority
enable PMTU discovery, it can reduce fragmentation but
causes connections to stall if not properly supported
.TP
\fB\-e \fR<\fIlocal ip\fR>
\fB\-e \fR<\fIlocal_ip_address\fR>
advertises the provided local IP address as preferred,
useful if multicast peer detection is not available, e.g.
disabled on routers
disabled on routers. \fB\-e auto\fR tries auto-detection of
local IP address.
.TP
\fB\-S1\fR ... \fB\-S2\fR
do not connect p2p, always use the supernode,

1
include/n2n_typedefs.h
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@ -652,6 +652,7 @@ typedef struct n2n_edge_conf {
int register_ttl; /**< TTL for registration packet when UDP NAT hole punching through supernode. */
in_addr_t bind_address; /**< The address to bind to if provided (-b) */
n2n_sock_t preferred_sock; /**< propagated local sock for better p2p in LAN (-e) */
uint8_t preferred_sock_auto; /**< indicates desired auto detect for preferred sock */
int local_port;
int mgmt_port;
uint8_t connect_tcp; /** connection to supernode 0 = UDP; 1 = TCP */

14
src/edge.c
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@ -255,7 +255,8 @@ static void help (int level) {
" | causes connections to stall if not properly supported\n");
#endif
printf(" -e <local ip> | advertises the provided local IP address as preferred,\n"
" | useful if multicast peer detection is not available\n");
" | useful if multicast peer detection is not available,\n"
" | '-e auto' tries IP address auto-detection\n");
printf(" -S1 ... -S2 | do not connect p2p, always use the supernode,\n"
" | -S1 = via UDP"
@ -615,8 +616,16 @@ static int setOption (int optkey, char *optargument, n2n_tuntap_priv_config_t *e
}
case 'e': {
in_addr_t address_tmp;
if(optargument) {
in_addr_t address_tmp = inet_addr(optargument);
if(!strcmp(optargument, "auto")) {
address_tmp = INADDR_ANY;
conf->preferred_sock_auto = 1;
} else {
address_tmp = inet_addr(optargument);
}
memcpy(&(conf->preferred_sock.addr.v4), &(address_tmp), IPV4_SIZE);
@ -1098,7 +1107,6 @@ int main (int argc, char* argv[]) {
eee->last_sup = 0; /* if it wasn't zero yet */
eee->curr_sn = eee->conf.supernodes;
supernode_connect(eee);
while(runlevel < 5) {
now = time(NULL);

43
src/edge_utils.c
View File

@ -203,8 +203,10 @@ void reset_sup_attempts (n2n_edge_t *eee) {
int supernode_connect(n2n_edge_t *eee) {
int sockopt;
struct sockaddr_in sock;
int sock_len = sizeof(sock);
struct sockaddr_in sn_sock;
struct sockaddr_in local_sock;
int sock_len = sizeof(local_sock);
SOCKET probe_sock;
if((eee->conf.connect_tcp) && (eee->sock >= 0)) {
closesocket(eee->sock);
@ -227,18 +229,7 @@ int supernode_connect(n2n_edge_t *eee) {
return -1;
}
// detetct local port, even/especially if chosen by OS...
if((getsockname(eee->sock, (struct sockaddr *)&sock, &sock_len) == 0)
&& (sock.sin_family == AF_INET)
&& (sock_len == sizeof(sock))) {
// ... and write to local preferred socket -- no matter if used or not
eee->conf.preferred_sock.port = ntohs(sock.sin_port);
}
// variable 'sock' gets re-used from here on (for sn)
sock.sin_family = eee->curr_sn->sock.family;
sock.sin_port = htons(eee->curr_sn->sock.port);
memcpy(&(sock.sin_addr.s_addr), &(eee->curr_sn->sock.addr.v4), IPV4_SIZE);
fill_sockaddr((struct sockaddr*)&sn_sock, sizeof(sn_sock), &eee->curr_sn->sock);
// set tcp socket to O_NONBLOCK so connect does not hang
// requires checking the socket for readiness before sending and receving
@ -249,7 +240,7 @@ int supernode_connect(n2n_edge_t *eee) {
#else
fcntl(eee->sock, F_SETFL, O_NONBLOCK);
#endif
if((connect(eee->sock, (struct sockaddr*)&(sock), sizeof(struct sockaddr)) < 0)
if((connect(eee->sock, (struct sockaddr*)&(sn_sock), sizeof(struct sockaddr)) < 0)
&& (errno != EINPROGRESS)) {
eee->sock = -1;
return -1;
@ -275,6 +266,28 @@ int supernode_connect(n2n_edge_t *eee) {
traceEvent(TRACE_INFO, "PMTU discovery %s", (eee->conf.disable_pmtu_discovery) ? "disabled" : "enabled");
#endif
// detetct local port even/especially if chosen by OS...
if((getsockname(eee->sock, (struct sockaddr *)&local_sock, &sock_len) == 0)
&& (local_sock.sin_family == AF_INET)
&& (sock_len == sizeof(local_sock))) {
// ... and write to local preferred socket -- no matter if used or not
eee->conf.preferred_sock.port = ntohs(local_sock.sin_port);
// probe for & overwrite local address only if auto-detection mode
if(eee->conf.preferred_sock_auto) {
probe_sock = socket(PF_INET, SOCK_DGRAM, 0);
// connecting the UDP socket makes getsockname read the local address it uses to connect (to the sn in this case)
// we cannot do it with the real (eee->sock) socket because socket does not accept any conenction from elsewhere then,
// e.g. from another edge instead of the supernode; hence, we use a temporary socket
connect(probe_sock, (struct sockaddr *)&sn_sock, sizeof(sn_sock));
if((getsockname(probe_sock, (struct sockaddr *)&local_sock, &sock_len) == 0)
&& (local_sock.sin_family == AF_INET)
&& (sock_len == sizeof(local_sock))) {
memcpy(&(eee->conf.preferred_sock.addr.v4), &(local_sock.sin_addr.s_addr), IPV4_SIZE);
}
close(probe_sock);
}
}
if(eee->cb.sock_opened)
eee->cb.sock_opened(eee);
}