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n2n/edge_utils.c
Luca Deri 9951a917c7 Updated (C)
2020-06-17 11:30:48 +05:45

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/**
* (C) 2007-20 - ntop.org and contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not see see <http://www.gnu.org/licenses/>
*
*/
#include "n2n.h"
#include "lzoconf.h"
#include "random_numbers.h"
#ifdef HAVE_LIBZSTD
#include <zstd.h>
#endif
#ifdef WIN32
#include <process.h>
/* Multicast peers discovery disabled due to https://github.com/ntop/n2n/issues/65 */
#define SKIP_MULTICAST_PEERS_DISCOVERY
#endif
#ifdef __ANDROID_NDK__
#include "android/edge_android.h"
#include <tun2tap/tun2tap.h>
#endif /* __ANDROID_NDK__ */
#define SOCKET_TIMEOUT_INTERVAL_SECS 10
#define REGISTER_SUPER_INTERVAL_DFL 20 /* sec, usually UDP NAT entries in a firewall expire after 30 seconds */
#define IFACE_UPDATE_INTERVAL (30) /* sec. How long it usually takes to get an IP lease. */
#define TRANSOP_TICK_INTERVAL (10) /* sec */
#ifdef __ANDROID_NDK__
#define ARP_PERIOD_INTERVAL (10) /* sec */
#endif
#ifdef __linux__
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#endif
#define ETH_FRAMESIZE 14
#define IP4_SRCOFFSET 12
#define IP4_DSTOFFSET 16
#define IP4_MIN_SIZE 20
#define UDP_SIZE 8
/* heap allocation for compression as per lzo example doc */
#define HEAP_ALLOC(var,size) lzo_align_t __LZO_MMODEL var [ ((size) + (sizeof(lzo_align_t) - 1)) / sizeof(lzo_align_t) ]
static HEAP_ALLOC(wrkmem, LZO1X_1_MEM_COMPRESS);
/* ************************************** */
static const char * supernode_ip(const n2n_edge_t * eee);
static void send_register(n2n_edge_t *eee, const n2n_sock_t *remote_peer, const n2n_mac_t peer_mac);
static void check_peer_registration_needed(n2n_edge_t * eee,
uint8_t from_supernode,
const n2n_mac_t mac,
const n2n_sock_t * peer);
static int edge_init_sockets(n2n_edge_t *eee, int udp_local_port, int mgmt_port, uint8_t tos);
static int edge_init_routes(n2n_edge_t *eee, n2n_route_t *routes, uint16_t num_routes);
static void edge_cleanup_routes(n2n_edge_t *eee);
static int supernode2addr(n2n_sock_t * sn, const n2n_sn_name_t addrIn);
static void check_known_peer_sock_change(n2n_edge_t * eee,
uint8_t from_supernode,
const n2n_mac_t mac,
const n2n_sock_t * peer,
time_t when);
/* ************************************** */
int edge_verify_conf(const n2n_edge_conf_t *conf) {
if(conf->community_name[0] == 0)
return(-1);
if(conf->sn_num == 0)
return(-2);
if(conf->register_interval < 1)
return(-3);
if(((conf->encrypt_key == NULL) && (conf->transop_id != N2N_TRANSFORM_ID_NULL)) ||
((conf->encrypt_key != NULL) && (conf->transop_id == N2N_TRANSFORM_ID_NULL)))
return(-4);
return(0);
}
/* ************************************** */
struct n2n_edge_stats {
uint32_t tx_p2p;
uint32_t rx_p2p;
uint32_t tx_sup;
uint32_t rx_sup;
uint32_t tx_sup_broadcast;
uint32_t rx_sup_broadcast;
};
/* ************************************** */
struct n2n_edge {
n2n_edge_conf_t conf;
/* Status */
uint8_t sn_idx; /**< Currently active supernode. */
uint8_t sn_wait; /**< Whether we are waiting for a supernode response. */
size_t sup_attempts; /**< Number of remaining attempts to this supernode. */
tuntap_dev device; /**< All about the TUNTAP device */
n2n_trans_op_t transop; /**< The transop to use when encoding */
n2n_cookie_t last_cookie; /**< Cookie sent in last REGISTER_SUPER. */
n2n_route_t *sn_route_to_clean; /**< Supernode route to clean */
/* Sockets */
n2n_sock_t supernode;
int udp_sock;
int udp_mgmt_sock; /**< socket for status info. */
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
n2n_sock_t multicast_peer; /**< Multicast peer group (for local edges) */
int udp_multicast_sock; /**< socket for local multicast registrations. */
int multicast_joined; /**< 1 if the group has been joined.*/
#endif
/* Peers */
struct peer_info * known_peers; /**< Edges we are connected to. */
struct peer_info * pending_peers; /**< Edges we have tried to register with. */
/* Timers */
time_t last_register_req; /**< Check if time to re-register with super*/
time_t last_p2p; /**< Last time p2p traffic was received. */
time_t last_sup; /**< Last time a packet arrived from supernode. */
time_t start_time; /**< For calculating uptime */
/* Statistics */
struct n2n_edge_stats stats;
};
/* ************************************** */
const char* transop_str(enum n2n_transform tr) {
switch(tr) {
case N2N_TRANSFORM_ID_NULL: return("null");
case N2N_TRANSFORM_ID_TWOFISH: return("twofish");
case N2N_TRANSFORM_ID_AESCBC: return("AES-CBC");
case N2N_TRANSFORM_ID_CHACHA20:return("ChaCha20");
case N2N_TRANSFORM_ID_SPECK :return("Speck");
default: return("invalid");
};
}
/* ************************************** */
const char* compression_str(uint8_t cmpr) {
switch(cmpr) {
case N2N_COMPRESSION_ID_NONE: return("none");
case N2N_COMPRESSION_ID_LZO: return("lzo1x");
#ifdef HAVE_LIBZSTD
case N2N_COMPRESSION_ID_ZSTD: return("zstd");
#endif
default: return("invalid");
};
}
/* ************************************** */
/** Destination 01:00:5E:00:00:00 - 01:00:5E:7F:FF:FF is multicast ethernet.
*/
static int is_ethMulticast(const void * buf, size_t bufsize) {
int retval = 0;
/* Match 01:00:5E:00:00:00 - 01:00:5E:7F:FF:FF */
if(bufsize >= sizeof(ether_hdr_t)) {
/* copy to aligned memory */
ether_hdr_t eh;
memcpy(&eh, buf, sizeof(ether_hdr_t));
if((0x01 == eh.dhost[0]) &&
(0x00 == eh.dhost[1]) &&
(0x5E == eh.dhost[2]) &&
(0 == (0x80 & eh.dhost[3])))
retval = 1; /* This is an ethernet multicast packet [RFC1112]. */
}
return retval;
}
/* ************************************** */
/** Destination MAC 33:33:0:00:00:00 - 33:33:FF:FF:FF:FF is reserved for IPv6
* neighbour discovery.
*/
static int is_ip6_discovery(const void * buf, size_t bufsize) {
int retval = 0;
if(bufsize >= sizeof(ether_hdr_t)) {
/* copy to aligned memory */
ether_hdr_t eh;
memcpy(&eh, buf, sizeof(ether_hdr_t));
if((0x33 == eh.dhost[0]) && (0x33 == eh.dhost[1]))
retval = 1; /* This is an IPv6 multicast packet [RFC2464]. */
}
return retval;
}
/* ************************************** */
/** Initialise an edge to defaults.
*
* This also initialises the NULL transform operation opstruct.
*/
n2n_edge_t* edge_init(const tuntap_dev *dev, const n2n_edge_conf_t *conf, int *rv) {
n2n_transform_t transop_id = conf->transop_id;
n2n_edge_t *eee = calloc(1, sizeof(n2n_edge_t));
int rc = -1, i;
if((rc = edge_verify_conf(conf)) != 0) {
traceEvent(TRACE_ERROR, "Invalid configuration");
goto edge_init_error;
}
if(!eee) {
traceEvent(TRACE_ERROR, "Cannot allocate memory");
goto edge_init_error;
}
#ifdef WIN32
initWin32();
#endif
memcpy(&eee->conf, conf, sizeof(*conf));
memcpy(&eee->device, dev, sizeof(*dev));
eee->start_time = time(NULL);
eee->known_peers = NULL;
eee->pending_peers = NULL;
eee->sup_attempts = N2N_EDGE_SUP_ATTEMPTS;
if(lzo_init() != LZO_E_OK) {
traceEvent(TRACE_ERROR, "LZO compression error");
goto edge_init_error;
}
#ifdef N2N_HAVE_ZSTD
// zstd does not require initialization. if it were required, this would be a good place
#endif
for(i=0; i<conf->sn_num; ++i)
traceEvent(TRACE_NORMAL, "supernode %u => %s\n", i, (conf->sn_ip_array[i]));
/* Set the active supernode */
supernode2addr(&(eee->supernode), conf->sn_ip_array[eee->sn_idx]);
/* Set active transop */
switch(transop_id) {
case N2N_TRANSFORM_ID_TWOFISH:
rc = n2n_transop_twofish_init(&eee->conf, &eee->transop);
break;
#ifdef N2N_HAVE_AES
case N2N_TRANSFORM_ID_AESCBC:
rc = n2n_transop_aes_cbc_init(&eee->conf, &eee->transop);
break;
#endif
#ifdef HAVE_OPENSSL_1_1
case N2N_TRANSFORM_ID_CHACHA20:
rc = n2n_transop_cc20_init(&eee->conf, &eee->transop);
break;
#endif
case N2N_TRANSFORM_ID_SPECK:
rc = n2n_transop_speck_init(&eee->conf, &eee->transop);
break;
default:
rc = n2n_transop_null_init(&eee->conf, &eee->transop);
}
if((rc < 0) || (eee->transop.fwd == NULL) || (eee->transop.transform_id != transop_id)) {
traceEvent(TRACE_ERROR, "Transop init failed");
goto edge_init_error;
}
if(eee->transop.no_encryption)
traceEvent(TRACE_WARNING, "Encryption is disabled in edge");
if(edge_init_sockets(eee, conf->local_port, conf->mgmt_port, conf->tos) < 0) {
traceEvent(TRACE_ERROR, "socket setup failed");
goto edge_init_error;
}
if(edge_init_routes(eee, conf->routes, conf->num_routes) < 0) {
traceEvent(TRACE_ERROR, "routes setup failed");
goto edge_init_error;
}
//edge_init_success:
*rv = 0;
return(eee);
edge_init_error:
if(eee)
free(eee);
*rv = rc;
return(NULL);
}
/* ************************************** */
static int find_and_remove_peer(struct peer_info **head, const n2n_mac_t mac) {
struct peer_info *peer;
HASH_FIND_PEER(*head, mac, peer);
if(peer) {
HASH_DEL(*head, peer);
free(peer);
return(1);
}
return(0);
}
/* ************************************** */
static uint32_t localhost_v4 = 0x7f000001;
static uint8_t localhost_v6[IPV6_SIZE] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
/* Exclude localhost as it may be received when an edge node runs
* in the same supernode host.
*/
static int is_valid_peer_sock(const n2n_sock_t *sock) {
switch(sock->family) {
case AF_INET:
{
uint32_t *a = (uint32_t*)sock->addr.v4;
if(*a != htonl(localhost_v4))
return(1);
}
break;
case AF_INET6:
if(memcmp(sock->addr.v6, localhost_v6, IPV6_SIZE))
return(1);
break;
}
return(0);
}
/* ***************************************************** */
/** Resolve the supernode IP address.
*
* REVISIT: This is a really bad idea. The edge will block completely while the
* hostname resolution is performed. This could take 15 seconds.
*/
static int supernode2addr(n2n_sock_t * sn, const n2n_sn_name_t addrIn) {
n2n_sn_name_t addr;
const char *supernode_host;
int rv = 0;
memcpy(addr, addrIn, N2N_EDGE_SN_HOST_SIZE);
supernode_host = strtok(addr, ":");
if(supernode_host) {
in_addr_t sn_addr;
char *supernode_port = strtok(NULL, ":");
const struct addrinfo aihints = {0, PF_INET, 0, 0, 0, NULL, NULL, NULL};
struct addrinfo * ainfo = NULL;
int nameerr;
if(supernode_port)
sn->port = atoi(supernode_port);
else
traceEvent(TRACE_WARNING, "Bad supernode parameter (-l <host:port>) %s %s:%s",
addr, supernode_host, supernode_port);
nameerr = getaddrinfo(supernode_host, NULL, &aihints, &ainfo);
if(0 == nameerr)
{
struct sockaddr_in * saddr;
/* ainfo s the head of a linked list if non-NULL. */
if(ainfo && (PF_INET == ainfo->ai_family))
{
/* It is definitely and IPv4 address -> sockaddr_in */
saddr = (struct sockaddr_in *)ainfo->ai_addr;
memcpy(sn->addr.v4, &(saddr->sin_addr.s_addr), IPV4_SIZE);
sn->family=AF_INET;
}
else
{
/* Should only return IPv4 addresses due to aihints. */
traceEvent(TRACE_WARNING, "Failed to resolve supernode IPv4 address for %s", supernode_host);
rv = -1;
}
freeaddrinfo(ainfo); /* free everything allocated by getaddrinfo(). */
ainfo = NULL;
} else {
traceEvent(TRACE_WARNING, "Failed to resolve supernode host %s, assuming numeric", supernode_host);
sn_addr = inet_addr(supernode_host); /* uint32_t */
memcpy(sn->addr.v4, &(sn_addr), IPV4_SIZE);
sn->family=AF_INET;
rv = -2;
}
} else {
traceEvent(TRACE_WARNING, "Wrong supernode parameter (-l <host:port>)");
rv = -3;
}
return(rv);
}
/* ************************************** */
/***
*
* Register over multicast in case there is a peer on the same network listening
*/
static void register_with_local_peers(n2n_edge_t * eee) {
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
if(eee->multicast_joined && eee->conf.allow_p2p) {
/* send registration to the local multicast group */
traceEvent(TRACE_DEBUG, "Registering with multicast group %s:%u",
N2N_MULTICAST_GROUP, N2N_MULTICAST_PORT);
send_register(eee, &(eee->multicast_peer), NULL);
}
#else
traceEvent(TRACE_DEBUG, "Multicast peers discovery is disabled, skipping");
#endif
}
/* ************************************** */
/** Start the registration process.
*
* If the peer is already in pending_peers, ignore the request.
* If not in pending_peers, add it and send a REGISTER.
*
* If hdr is for a direct peer-to-peer packet, try to register back to sender
* even if the MAC is in pending_peers. This is because an incident direct
* packet indicates that peer-to-peer exchange should work so more aggressive
* registration can be permitted (once per incoming packet) as this should only
* last for a small number of packets..
*
* Called from the main loop when Rx a packet for our device mac.
*/
static void register_with_new_peer(n2n_edge_t * eee,
uint8_t from_supernode,
const n2n_mac_t mac,
const n2n_sock_t * peer) {
/* REVISIT: purge of pending_peers not yet done. */
struct peer_info * scan;
macstr_t mac_buf;
n2n_sock_str_t sockbuf;
HASH_FIND_PEER(eee->pending_peers, mac, scan);
/* NOTE: pending_peers are purged periodically with purge_expired_registrations */
if(scan == NULL) {
scan = calloc(1, sizeof(struct peer_info));
memcpy(scan->mac_addr, mac, N2N_MAC_SIZE);
scan->sock = *peer;
scan->timeout = REGISTER_SUPER_INTERVAL_DFL; /* TODO: should correspond to the peer supernode registration timeout */
scan->last_seen = time(NULL); /* Don't change this it marks the pending peer for removal. */
HASH_ADD_PEER(eee->pending_peers, scan);
traceEvent(TRACE_DEBUG, "=== new pending %s -> %s",
macaddr_str(mac_buf, scan->mac_addr),
sock_to_cstr(sockbuf, &(scan->sock)));
traceEvent(TRACE_DEBUG, "Pending peers list size=%u",
HASH_COUNT(eee->pending_peers));
/* trace Sending REGISTER */
if(from_supernode) {
/* UDP NAT hole punching through supernode. Send to peer first(punch local UDP hole)
* and then ask supernode to forward. Supernode then ask peer to ack. Some nat device
* drop and block ports with incoming UDP packet if out-come traffic does not exist.
* So we can alternatively set TTL so that the packet sent to peer never really reaches
* The register_ttl is basically nat level + 1. Set it to 1 means host like DMZ.
*/
if (eee->conf.register_ttl == 1) {
/* We are DMZ host or port is directly accessible. Just let peer to send back the ack */
#ifndef WIN32
} else if(eee->conf.register_ttl > 1) {
/* Setting register_ttl usually implies that the edge knows the internal net topology
* clearly, we can apply aggressive port prediction to support incoming Symmetric NAT
*/
int curTTL = 0;
socklen_t lenTTL = sizeof(int);
n2n_sock_t sock = scan->sock;
int alter = 16; /* TODO: set by command line or more reliable prediction method */
getsockopt(eee->udp_sock, IPPROTO_IP, IP_TTL, (void *)(char *)&curTTL, &lenTTL);
setsockopt(eee->udp_sock, IPPROTO_IP, IP_TTL,
(void *)(char *)&eee->conf.register_ttl,
sizeof(eee->conf.register_ttl));
for (; alter > 0; alter--, sock.port++)
{
send_register(eee, &sock, mac);
}
setsockopt(eee->udp_sock, IPPROTO_IP, IP_TTL, (void *)(char *)&curTTL, sizeof(curTTL));
#endif
} else { /* eee->conf.register_ttl <= 0 */
/* Normal STUN */
send_register(eee, &(scan->sock), mac);
}
send_register(eee, &(eee->supernode), mac);
} else {
/* P2P register, send directly */
send_register(eee, &(scan->sock), mac);
}
register_with_local_peers(eee);
} else
scan->sock = *peer;
}
/* ************************************** */
/** Update the last_seen time for this peer, or get registered. */
static void check_peer_registration_needed(n2n_edge_t * eee,
uint8_t from_supernode,
const n2n_mac_t mac,
const n2n_sock_t * peer) {
struct peer_info *scan;
HASH_FIND_PEER(eee->known_peers, mac, scan);
if(scan == NULL) {
/* Not in known_peers - start the REGISTER process. */
register_with_new_peer(eee, from_supernode, mac, peer);
} else {
/* Already in known_peers. */
time_t now = time(NULL);
if(!from_supernode)
scan->last_p2p = now;
if((now - scan->last_seen) > 0 /* >= 1 sec */) {
/* Don't register too often */
check_known_peer_sock_change(eee, from_supernode, mac, peer, now);
}
}
}
/* ************************************** */
/* Confirm that a pending peer is reachable directly via P2P.
*
* peer must be a pointer to an element of the pending_peers list.
*/
static void peer_set_p2p_confirmed(n2n_edge_t * eee,
const n2n_mac_t mac,
const n2n_sock_t * peer,
time_t now) {
struct peer_info *scan;
macstr_t mac_buf;
n2n_sock_str_t sockbuf;
HASH_FIND_PEER(eee->pending_peers, mac, scan);
if(scan) {
HASH_DEL(eee->pending_peers, scan);
/* Add scan to known_peers. */
HASH_ADD_PEER(eee->known_peers, scan);
scan->sock = *peer;
scan->last_p2p = now;
traceEvent(TRACE_NORMAL, "P2P connection established: %s [%s]",
macaddr_str(mac_buf, mac),
sock_to_cstr(sockbuf, peer));
traceEvent(TRACE_DEBUG, "=== new peer %s -> %s",
macaddr_str(mac_buf, scan->mac_addr),
sock_to_cstr(sockbuf, &(scan->sock)));
traceEvent(TRACE_DEBUG, "Pending peers list size=%u",
HASH_COUNT(eee->pending_peers));
traceEvent(TRACE_DEBUG, "Known peers list size=%u",
HASH_COUNT(eee->known_peers));
scan->last_seen = now;
} else
traceEvent(TRACE_DEBUG, "Failed to find sender in pending_peers.");
}
/* ************************************** */
int is_empty_ip_address(const n2n_sock_t * sock) {
const uint8_t * ptr=NULL;
size_t len=0;
size_t i;
if(AF_INET6 == sock->family)
{
ptr = sock->addr.v6;
len = 16;
}
else
{
ptr = sock->addr.v4;
len = 4;
}
for (i=0; i<len; ++i)
{
if(0 != ptr[i])
{
/* found a non-zero byte in address */
return 0;
}
}
return 1;
}
/* ************************************** */
static n2n_mac_t broadcast_mac = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
/** Check if a known peer socket has changed and possibly register again.
*/
static void check_known_peer_sock_change(n2n_edge_t * eee,
uint8_t from_supernode,
const n2n_mac_t mac,
const n2n_sock_t * peer,
time_t when) {
struct peer_info *scan;
n2n_sock_str_t sockbuf1;
n2n_sock_str_t sockbuf2; /* don't clobber sockbuf1 if writing two addresses to trace */
macstr_t mac_buf;
if(is_empty_ip_address(peer))
return;
if(!memcmp(mac, broadcast_mac, N2N_MAC_SIZE))
return;
/* Search the peer in known_peers */
HASH_FIND_PEER(eee->known_peers, mac, scan);
if(!scan)
/* Not in known_peers */
return;
if(!sock_equal(&(scan->sock), peer)) {
if(!from_supernode) {
/* This is a P2P packet */
traceEvent(TRACE_NORMAL, "Peer changed %s: %s -> %s",
macaddr_str(mac_buf, scan->mac_addr),
sock_to_cstr(sockbuf1, &(scan->sock)),
sock_to_cstr(sockbuf2, peer));
/* The peer has changed public socket. It can no longer be assumed to be reachable. */
HASH_DEL(eee->known_peers, scan);
free(scan);
register_with_new_peer(eee, from_supernode, mac, peer);
} else {
/* Don't worry about what the supernode reports, it could be seeing a different socket. */
}
} else
scan->last_seen = when;
}
/* ************************************** */
/** Send a datagram to a socket defined by a n2n_sock_t */
static ssize_t sendto_sock(int fd, const void * buf,
size_t len, const n2n_sock_t * dest) {
struct sockaddr_in peer_addr;
ssize_t sent;
fill_sockaddr((struct sockaddr *) &peer_addr,
sizeof(peer_addr),
dest);
sent = sendto(fd, buf, len, 0/*flags*/,
(struct sockaddr *)&peer_addr, sizeof(struct sockaddr_in));
if(sent < 0)
{
char * c = strerror(errno);
traceEvent(TRACE_ERROR, "sendto failed (%d) %s", errno, c);
}
else
{
traceEvent(TRACE_DEBUG, "sendto sent=%d to ", (signed int)sent);
}
return sent;
}
/* ************************************** */
/* Bind eee->udp_multicast_sock to multicast group */
static void check_join_multicast_group(n2n_edge_t *eee) {
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
if(!eee->multicast_joined) {
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = inet_addr(N2N_MULTICAST_GROUP);
mreq.imr_interface.s_addr = htonl(INADDR_ANY);
if(setsockopt(eee->udp_multicast_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&mreq, sizeof(mreq)) < 0) {
traceEvent(TRACE_WARNING, "Failed to bind to local multicast group %s:%u [errno %u]",
N2N_MULTICAST_GROUP, N2N_MULTICAST_PORT, errno);
#ifdef WIN32
traceEvent(TRACE_ERROR, "WSAGetLastError(): %u", WSAGetLastError());
#endif
} else {
traceEvent(TRACE_NORMAL, "Successfully joined multicast group %s:%u",
N2N_MULTICAST_GROUP, N2N_MULTICAST_PORT);
eee->multicast_joined = 1;
}
}
#endif
}
/* ************************************** */
/** Send a REGISTER_SUPER packet to the current supernode. */
static void send_register_super(n2n_edge_t * eee,
const n2n_sock_t * supernode) {
uint8_t pktbuf[N2N_PKT_BUF_SIZE] = {0};
size_t idx;
/* ssize_t sent; */
n2n_common_t cmn;
n2n_REGISTER_SUPER_t reg;
n2n_sock_str_t sockbuf;
memset(&cmn, 0, sizeof(cmn));
memset(&reg, 0, sizeof(reg));
cmn.ttl=N2N_DEFAULT_TTL;
cmn.pc = n2n_register_super;
cmn.flags = 0;
memcpy(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE);
for(idx=0; idx < N2N_COOKIE_SIZE; ++idx)
eee->last_cookie[idx] = n2n_rand() % 0xff;
memcpy(reg.cookie, eee->last_cookie, N2N_COOKIE_SIZE);
reg.auth.scheme=0; /* No auth yet */
idx=0;
encode_mac(reg.edgeMac, &idx, eee->device.mac_addr);
idx=0;
encode_REGISTER_SUPER(pktbuf, &idx, &cmn, &reg);
traceEvent(TRACE_DEBUG, "send REGISTER_SUPER to %s",
sock_to_cstr(sockbuf, supernode));
/* sent = */ sendto_sock(eee->udp_sock, pktbuf, idx, supernode);
}
/* ************************************** */
/** Send a QUERY_PEER packet to the current supernode. */
static void send_query_peer( n2n_edge_t * eee,
const n2n_mac_t dstMac) {
uint8_t pktbuf[N2N_PKT_BUF_SIZE];
size_t idx;
n2n_common_t cmn = {0};
n2n_QUERY_PEER_t query = {{0}};
cmn.ttl=N2N_DEFAULT_TTL;
cmn.pc = n2n_query_peer;
cmn.flags = 0;
memcpy( cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE );
idx=0;
encode_mac( query.srcMac, &idx, eee->device.mac_addr );
idx=0;
encode_mac( query.targetMac, &idx, dstMac );
idx=0;
encode_QUERY_PEER( pktbuf, &idx, &cmn, &query );
traceEvent( TRACE_DEBUG, "send QUERY_PEER to supernode" );
sendto_sock( eee->udp_sock, pktbuf, idx, &(eee->supernode) );
}
/** Send a REGISTER packet to another edge. */
static void send_register(n2n_edge_t * eee,
const n2n_sock_t * remote_peer,
const n2n_mac_t peer_mac) {
uint8_t pktbuf[N2N_PKT_BUF_SIZE];
size_t idx;
/* ssize_t sent; */
n2n_common_t cmn;
n2n_REGISTER_t reg;
n2n_sock_str_t sockbuf;
if(!eee->conf.allow_p2p) {
traceEvent(TRACE_DEBUG, "Skipping register as P2P is disabled");
return;
}
memset(&cmn, 0, sizeof(cmn));
memset(&reg, 0, sizeof(reg));
cmn.ttl=N2N_DEFAULT_TTL;
cmn.pc = n2n_register;
cmn.flags = 0;
memcpy(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE);
idx=0;
encode_uint32(reg.cookie, &idx, 123456789);
idx=0;
encode_mac(reg.srcMac, &idx, eee->device.mac_addr);
if(peer_mac) {
/* Can be NULL for multicast registrations */
idx=0;
encode_mac(reg.dstMac, &idx, peer_mac);
}
idx=0;
encode_REGISTER(pktbuf, &idx, &cmn, &reg);
traceEvent(TRACE_INFO, "Send REGISTER to %s",
sock_to_cstr(sockbuf, remote_peer));
/* sent = */ sendto_sock(eee->udp_sock, pktbuf, idx, remote_peer);
}
/* ************************************** */
/** Send a REGISTER_ACK packet to a peer edge. */
static void send_register_ack(n2n_edge_t * eee,
const n2n_sock_t * remote_peer,
const n2n_REGISTER_t * reg) {
uint8_t pktbuf[N2N_PKT_BUF_SIZE];
size_t idx;
/* ssize_t sent; */
n2n_common_t cmn;
n2n_REGISTER_ACK_t ack;
n2n_sock_str_t sockbuf;
if(!eee->conf.allow_p2p) {
traceEvent(TRACE_DEBUG, "Skipping register ACK as P2P is disabled");
return;
}
memset(&cmn, 0, sizeof(cmn));
memset(&ack, 0, sizeof(reg));
cmn.ttl=N2N_DEFAULT_TTL;
cmn.pc = n2n_register_ack;
cmn.flags = 0;
memcpy(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE);
memset(&ack, 0, sizeof(ack));
memcpy(ack.cookie, reg->cookie, N2N_COOKIE_SIZE);
memcpy(ack.srcMac, eee->device.mac_addr, N2N_MAC_SIZE);
memcpy(ack.dstMac, reg->srcMac, N2N_MAC_SIZE);
idx=0;
encode_REGISTER_ACK(pktbuf, &idx, &cmn, &ack);
traceEvent(TRACE_INFO, "send REGISTER_ACK %s",
sock_to_cstr(sockbuf, remote_peer));
/* sent = */ sendto_sock(eee->udp_sock, pktbuf, idx, remote_peer);
}
/* ************************************** */
/** @brief Check to see if we should re-register with the supernode.
*
* This is frequently called by the main loop.
*/
static void update_supernode_reg(n2n_edge_t * eee, time_t nowTime) {
u_int sn_idx;
if(eee->sn_wait && (nowTime > (eee->last_register_req + (eee->conf.register_interval/10)))) {
/* fall through */
traceEvent(TRACE_DEBUG, "update_supernode_reg: doing fast retry.");
} else if(nowTime < (eee->last_register_req + eee->conf.register_interval))
return; /* Too early */
check_join_multicast_group(eee);
if(0 == eee->sup_attempts) {
/* Give up on that supernode and try the next one. */
++(eee->sn_idx);
if (eee->sn_idx >= eee->conf.sn_num) {
/* Got to end of list, go back to the start. Also works for list of one entry. */
eee->sn_idx=0;
}
traceEvent(TRACE_WARNING, "Supernode not responding, now trying %s", supernode_ip(eee));
eee->sup_attempts = N2N_EDGE_SUP_ATTEMPTS;
}
else
--(eee->sup_attempts);
for(sn_idx=0; sn_idx<eee->conf.sn_num; sn_idx++) {
supernode2addr(&(eee->supernode), eee->conf.sn_ip_array[sn_idx]);
traceEvent(TRACE_INFO, "Registering with supernode [id: %u/%u][%s][attempts left %u]",
sn_idx+1, eee->conf.sn_num,
supernode_ip(eee), (unsigned int)eee->sup_attempts);
send_register_super(eee, &(eee->supernode));
}
register_with_local_peers(eee);
eee->sn_wait=1;
/* REVISIT: turn-on gratuitous ARP with config option. */
/* send_grat_arps(sock_fd, is_udp_sock); */
eee->last_register_req = nowTime;
}
/* ************************************** */
/** NOT IMPLEMENTED
*
* This would send a DEREGISTER packet to a peer edge or supernode to indicate
* the edge is going away.
*/
static void send_deregister(n2n_edge_t * eee,
n2n_sock_t * remote_peer) {
/* Marshall and send message */
}
/* ************************************** */
/** Return the IP address of the current supernode in the ring. */
static const char * supernode_ip(const n2n_edge_t * eee) {
return (eee->conf.sn_ip_array)[eee->sn_idx];
}
/* ************************************** */
/** A PACKET has arrived containing an encapsulated ethernet datagram - usually
* encrypted. */
static int handle_PACKET(n2n_edge_t * eee,
const n2n_common_t * cmn,
const n2n_PACKET_t * pkt,
const n2n_sock_t * orig_sender,
uint8_t * payload,
size_t psize) {
ssize_t data_sent_len;
uint8_t from_supernode;
uint8_t * eth_payload=NULL;
int retval = -1;
time_t now;
ether_hdr_t * eh;
ipstr_t ip_buf;
now = time(NULL);
traceEvent(TRACE_DEBUG, "handle_PACKET size %u transform %u",
(unsigned int)psize, (unsigned int)pkt->transform);
/* hexdump(payload, psize); */
from_supernode= cmn->flags & N2N_FLAGS_FROM_SUPERNODE;
if(from_supernode)
{
if(!memcmp(pkt->dstMac, broadcast_mac, 6))
++(eee->stats.rx_sup_broadcast);
++(eee->stats.rx_sup);
eee->last_sup=now;
}
else
{
++(eee->stats.rx_p2p);
eee->last_p2p=now;
}
/* Update the sender in peer table entry */
check_peer_registration_needed(eee, from_supernode, pkt->srcMac, orig_sender);
/* Handle transform. */
{
uint8_t decodebuf[N2N_PKT_BUF_SIZE];
size_t eth_size;
n2n_transform_t rx_transop_id;
rx_transop_id = (n2n_transform_t)pkt->transform;
/* optional compression is encoded in uppermost bit of transform field.
* this is an intermediate solution to maintain compatibility until some
* upcoming major release (3.0?) brings up changes in packet structure anyway
* in the course of which a dedicated compression field could be spent.
* REVISIT then. */
uint16_t rx_compression_id;
rx_compression_id = (uint16_t)rx_transop_id >> (8*sizeof((uint16_t)rx_transop_id)-N2N_COMPRESSION_ID_BITLEN);
rx_transop_id &= (1 << (8*sizeof((uint16_t)rx_transop_id)-N2N_COMPRESSION_ID_BITLEN)) -1;
if(rx_transop_id == eee->conf.transop_id) {
uint8_t is_multicast;
eth_payload = decodebuf;
eh = (ether_hdr_t*)eth_payload;
eth_size = eee->transop.rev(&eee->transop,
eth_payload, N2N_PKT_BUF_SIZE,
payload, psize, pkt->srcMac);
++(eee->transop.rx_cnt); /* stats */
/* decompress if necessary */
uint8_t * deflation_buffer = 0;
int32_t deflated_len;
switch (rx_compression_id) {
case N2N_COMPRESSION_ID_NONE:
break; // continue afterwards
case N2N_COMPRESSION_ID_LZO:
deflation_buffer = malloc (N2N_PKT_BUF_SIZE);
lzo1x_decompress (eth_payload, eth_size, deflation_buffer, (lzo_uint*)&deflated_len, NULL);
break;
#ifdef N2N_HAVE_ZSTD
case N2N_COMPRESSION_ID_ZSTD:
deflated_len = N2N_PKT_BUF_SIZE;
deflation_buffer = malloc (deflated_len);
deflated_len = (int32_t)ZSTD_decompress (deflation_buffer, deflated_len, eth_payload, eth_size);
if (ZSTD_isError(deflated_len)) {
traceEvent (TRACE_ERROR, "payload decompression failed with zstd error '%s'.",
ZSTD_getErrorName(deflated_len));
free (deflation_buffer);
return (-1); // cannot help it
}
break;
#endif
default:
traceEvent (TRACE_ERROR, "payload decompression failed: received packet indicating unsupported %s compression.",
compression_str(rx_compression_id));
return (-1); // cannot handle it
}
if (rx_compression_id) {
traceEvent (TRACE_DEBUG, "payload decompression [%s]: deflated %u bytes to %u bytes",
compression_str(rx_compression_id), eth_size, (int)deflated_len);
memcpy(eth_payload ,deflation_buffer, deflated_len );
eth_size = deflated_len;
free (deflation_buffer);
}
is_multicast = (is_ip6_discovery(eth_payload, eth_size) || is_ethMulticast(eth_payload, eth_size));
if(eee->conf.drop_multicast && is_multicast) {
traceEvent(TRACE_INFO, "Dropping RX multicast");
return(-1);
} else if((!eee->conf.allow_routing) && (!is_multicast)) {
/* Check if it is a routed packet */
if((ntohs(eh->type) == 0x0800) && (eth_size >= ETH_FRAMESIZE + IP4_MIN_SIZE)) {
uint32_t *dst = (uint32_t*)&eth_payload[ETH_FRAMESIZE + IP4_DSTOFFSET];
u_int8_t *dst_mac = (u_int8_t*)eth_payload;
/* Note: all elements of the_ip are in network order */
if(!memcmp(dst_mac, broadcast_mac, 6))
traceEvent(TRACE_DEBUG, "Broadcast packet [%s]",
intoa(ntohl(*dst), ip_buf, sizeof(ip_buf)));
else if((*dst != eee->device.ip_addr)) {
/* This is a packet that needs to be routed */
traceEvent(TRACE_INFO, "Discarding routed packet [%s]",
intoa(ntohl(*dst), ip_buf, sizeof(ip_buf)));
return(-1);
} else {
/* This packet is directed to us */
/* traceEvent(TRACE_INFO, "Sending non-routed packet"); */
}
}
}
/* Write ethernet packet to tap device. */
traceEvent(TRACE_DEBUG, "sending to TAP %u", (unsigned int)eth_size);
data_sent_len = tuntap_write(&(eee->device), eth_payload, eth_size);
if (data_sent_len == eth_size)
{
retval = 0;
}
}
else
{
traceEvent(TRACE_ERROR, "invalid transop ID: expected %s(%u), got %s(%u)",
transop_str(eee->conf.transop_id), eee->conf.transop_id,
transop_str(rx_transop_id), rx_transop_id);
}
}
return retval;
}
/* ************************************** */
/** Read a datagram from the management UDP socket and take appropriate
* action. */
static void readFromMgmtSocket(n2n_edge_t * eee, int * keep_running) {
uint8_t udp_buf[N2N_PKT_BUF_SIZE]; /* Compete UDP packet */
ssize_t recvlen;
/* ssize_t sendlen; */
struct sockaddr_in sender_sock;
socklen_t i;
size_t msg_len;
time_t now;
now = time(NULL);
i = sizeof(sender_sock);
recvlen = recvfrom(eee->udp_mgmt_sock, udp_buf, N2N_PKT_BUF_SIZE, 0/*flags*/,
(struct sockaddr *)&sender_sock, (socklen_t*)&i);
if(recvlen < 0)
{
traceEvent(TRACE_ERROR, "mgmt recvfrom failed with %s", strerror(errno));
return; /* failed to receive data from UDP */
}
if(recvlen >= 4)
{
if(0 == memcmp(udp_buf, "stop", 4))
{
traceEvent(TRACE_ERROR, "stop command received.");
*keep_running = 0;
return;
}
if(0 == memcmp(udp_buf, "help", 4))
{
msg_len=0;
setTraceLevel(getTraceLevel()+1);
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"Help for edge management console:\n"
" stop Gracefully exit edge\n"
" help This help message\n"
" +verb Increase verbosity of logging\n"
" -verb Decrease verbosity of logging\n"
" <enter> Display statistics\n\n");
sendto(eee->udp_mgmt_sock, udp_buf, msg_len, 0/*flags*/,
(struct sockaddr *)&sender_sock, sizeof(struct sockaddr_in));
return;
}
}
if(recvlen >= 5)
{
if(0 == memcmp(udp_buf, "+verb", 5))
{
msg_len=0;
setTraceLevel(getTraceLevel()+1);
traceEvent(TRACE_ERROR, "+verb traceLevel=%u", (unsigned int)getTraceLevel());
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"> +OK traceLevel=%u\n", (unsigned int)getTraceLevel());
sendto(eee->udp_mgmt_sock, udp_buf, msg_len, 0/*flags*/,
(struct sockaddr *)&sender_sock, sizeof(struct sockaddr_in));
return;
}
if(0 == memcmp(udp_buf, "-verb", 5))
{
msg_len=0;
if(getTraceLevel() > 0)
{
setTraceLevel(getTraceLevel()-1);
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"> -OK traceLevel=%u\n", getTraceLevel());
}
else
{
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"> -NOK traceLevel=%u\n", getTraceLevel());
}
traceEvent(TRACE_ERROR, "-verb traceLevel=%u", (unsigned int)getTraceLevel());
sendto(eee->udp_mgmt_sock, udp_buf, msg_len, 0/*flags*/,
(struct sockaddr *)&sender_sock, sizeof(struct sockaddr_in));
return;
}
}
traceEvent(TRACE_DEBUG, "mgmt status rq");
msg_len=0;
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"Statistics for edge\n");
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"uptime %lu\n",
time(NULL) - eee->start_time);
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"paths super:%u,%u p2p:%u,%u\n",
(unsigned int)eee->stats.tx_sup,
(unsigned int)eee->stats.rx_sup,
(unsigned int)eee->stats.tx_p2p,
(unsigned int)eee->stats.rx_p2p);
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"transop |%6u|%6u|\n",
(unsigned int)eee->transop.tx_cnt,
(unsigned int)eee->transop.rx_cnt);
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"peers pend:%u full:%u\n",
HASH_COUNT(eee->pending_peers),
HASH_COUNT(eee->known_peers));
msg_len += snprintf((char *)(udp_buf+msg_len), (N2N_PKT_BUF_SIZE-msg_len),
"last super:%lu(%ld sec ago) p2p:%lu(%ld sec ago)\n",
eee->last_sup, (now-eee->last_sup), eee->last_p2p,
(now-eee->last_p2p));
traceEvent(TRACE_DEBUG, "mgmt status sending: %s", udp_buf);
/* sendlen = */ sendto(eee->udp_mgmt_sock, udp_buf, msg_len, 0/*flags*/,
(struct sockaddr *)&sender_sock, sizeof(struct sockaddr_in));
}
/* ************************************** */
static int check_query_peer_info(n2n_edge_t *eee, time_t now, n2n_mac_t mac) {
struct peer_info *scan;
HASH_FIND_PEER(eee->pending_peers, mac, scan);
if(!scan) {
scan = calloc(1, sizeof(struct peer_info));
memcpy(scan->mac_addr, mac, N2N_MAC_SIZE);
scan->timeout = REGISTER_SUPER_INTERVAL_DFL; /* TODO: should correspond to the peer supernode registration timeout */
scan->last_seen = now; /* Don't change this it marks the pending peer for removal. */
HASH_ADD_PEER(eee->pending_peers, scan);
}
if(now - scan->last_sent_query > REGISTER_SUPER_INTERVAL_DFL) {
send_query_peer(eee, scan->mac_addr);
scan->last_sent_query = now;
return(0);
}
return(1);
}
/* ************************************** */
/* @return 1 if destination is a peer, 0 if destination is supernode */
static int find_peer_destination(n2n_edge_t * eee,
n2n_mac_t mac_address,
n2n_sock_t * destination) {
struct peer_info *scan;
macstr_t mac_buf;
n2n_sock_str_t sockbuf;
int retval=0;
time_t now = time(NULL);
if(!memcmp(mac_address, broadcast_mac, 6)) {
traceEvent(TRACE_DEBUG, "Broadcast destination peer, using supernode");
memcpy(destination, &(eee->supernode), sizeof(struct sockaddr_in));
return(0);
}
traceEvent(TRACE_DEBUG, "Searching destination peer for MAC %02X:%02X:%02X:%02X:%02X:%02X",
mac_address[0] & 0xFF, mac_address[1] & 0xFF, mac_address[2] & 0xFF,
mac_address[3] & 0xFF, mac_address[4] & 0xFF, mac_address[5] & 0xFF);
HASH_FIND_PEER(eee->known_peers, mac_address, scan);
if(scan && (scan->last_seen > 0)) {
if((now - scan->last_p2p) >= (scan->timeout / 2)) {
/* Too much time passed since we saw the peer, need to register again
* since the peer address may have changed. */
traceEvent(TRACE_DEBUG, "Refreshing idle known peer");
HASH_DEL(eee->known_peers, scan);
free(scan);
/* NOTE: registration will be performed upon the receival of the next response packet */
} else {
/* Valid known peer found */
memcpy(destination, &scan->sock, sizeof(n2n_sock_t));
retval=1;
}
}
if(retval == 0) {
memcpy(destination, &(eee->supernode), sizeof(struct sockaddr_in));
traceEvent(TRACE_DEBUG, "P2P Peer [MAC=%02X:%02X:%02X:%02X:%02X:%02X] not found, using supernode",
mac_address[0] & 0xFF, mac_address[1] & 0xFF, mac_address[2] & 0xFF,
mac_address[3] & 0xFF, mac_address[4] & 0xFF, mac_address[5] & 0xFF);
check_query_peer_info(eee, now, mac_address);
}
traceEvent(TRACE_DEBUG, "find_peer_address (%s) -> [%s]",
macaddr_str(mac_buf, mac_address),
sock_to_cstr(sockbuf, destination));
return retval;
}
/* ***************************************************** */
/** Send an ecapsulated ethernet PACKET to a destination edge or broadcast MAC
* address. */
static int send_packet(n2n_edge_t * eee,
n2n_mac_t dstMac,
const uint8_t * pktbuf,
size_t pktlen) {
int is_p2p;
/*ssize_t s; */
n2n_sock_str_t sockbuf;
n2n_sock_t destination;
macstr_t mac_buf;
/* hexdump(pktbuf, pktlen); */
is_p2p = find_peer_destination(eee, dstMac, &destination);
if(is_p2p)
++(eee->stats.tx_p2p);
else {
++(eee->stats.tx_sup);
if(!memcmp(dstMac, broadcast_mac, 6))
++(eee->stats.tx_sup_broadcast);
}
traceEvent(TRACE_INFO, "Tx PACKET to %s (dest=%s) [%u B]",
sock_to_cstr(sockbuf, &destination),
macaddr_str(mac_buf, dstMac), pktlen);
/* s = */ sendto_sock(eee->udp_sock, pktbuf, pktlen, &destination);
return 0;
}
/* ************************************** */
/** A layer-2 packet was received at the tunnel and needs to be sent via UDP. */
static void send_packet2net(n2n_edge_t * eee,
uint8_t *tap_pkt, size_t len) {
ipstr_t ip_buf;
n2n_mac_t destMac;
n2n_common_t cmn;
n2n_PACKET_t pkt;
uint8_t pktbuf[N2N_PKT_BUF_SIZE];
size_t idx=0;
n2n_transform_t tx_transop_idx = eee->transop.transform_id;
ether_hdr_t eh;
/* tap_pkt is not aligned so we have to copy to aligned memory */
memcpy(&eh, tap_pkt, sizeof(ether_hdr_t));
/* Discard IP packets that are not originated by this hosts */
if(!(eee->conf.allow_routing)) {
if(ntohs(eh.type) == 0x0800) {
/* This is an IP packet from the local source address - not forwarded. */
uint32_t *src = (uint32_t*)&tap_pkt[ETH_FRAMESIZE + IP4_SRCOFFSET];
/* Note: all elements of the_ip are in network order */
if(*src != eee->device.ip_addr) {
/* This is a packet that needs to be routed */
traceEvent(TRACE_INFO, "Discarding routed packet [%s]",
intoa(ntohl(*src), ip_buf, sizeof(ip_buf)));
return;
} else {
/* This packet is originated by us */
/* traceEvent(TRACE_INFO, "Sending non-routed packet"); */
}
}
}
/* Optionally compress then apply transforms, eg encryption. */
/* Once processed, send to destination in PACKET */
memcpy(destMac, tap_pkt, N2N_MAC_SIZE); /* dest MAC is first in ethernet header */
memset(&cmn, 0, sizeof(cmn));
cmn.ttl = N2N_DEFAULT_TTL;
cmn.pc = n2n_packet;
cmn.flags=0; /* no options, not from supernode, no socket */
memcpy(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE);
memset(&pkt, 0, sizeof(pkt));
memcpy(pkt.srcMac, eee->device.mac_addr, N2N_MAC_SIZE);
memcpy(pkt.dstMac, destMac, N2N_MAC_SIZE);
pkt.sock.family=0; /* do not encode sock */
pkt.transform = tx_transop_idx;
// compression needs to be tried before encode_PACKET is called for compression indication gets encoded there
pkt.compression = N2N_COMPRESSION_ID_NONE;
if (eee->conf.compression) {
uint8_t * compression_buffer;
int32_t compression_len;
switch (eee->conf.compression) {
case N2N_COMPRESSION_ID_LZO:
compression_buffer = malloc (len + len / 16 + 64 + 3);
if (lzo1x_1_compress(tap_pkt, len, compression_buffer, (lzo_uint*)&compression_len, wrkmem) == LZO_E_OK) {
if (compression_len < len) {
pkt.compression = N2N_COMPRESSION_ID_LZO;
}
}
break;
#ifdef N2N_HAVE_ZSTD
case N2N_COMPRESSION_ID_ZSTD:
compression_len = N2N_PKT_BUF_SIZE + 128;
compression_buffer = malloc (compression_len); // leaves enough room, for exact size call compression_len = ZSTD_compressBound (len); (slower)
compression_len = (int32_t)ZSTD_compress(compression_buffer, compression_len, tap_pkt, len, ZSTD_COMPRESSION_LEVEL) ;
if (!ZSTD_isError(compression_len)) {
if (compression_len < len) {
pkt.compression = N2N_COMPRESSION_ID_ZSTD;
}
} else {
traceEvent (TRACE_ERROR, "payload compression failed with zstd error '%s'.",
ZSTD_getErrorName(compression_len));
free (compression_buffer);
// continue with unset without pkt.compression --> will send uncompressed
}
break;
#endif
default:
break;
}
if (pkt.compression) {
traceEvent (TRACE_DEBUG, "payload compression [%s]: compressed %u bytes to %u bytes\n",
compression_str(pkt.compression), len, compression_len);
memcpy (tap_pkt, compression_buffer, compression_len);
len = compression_len;
free (compression_buffer);
}
}
/* optional compression is encoded in uppermost bits of transform field.
* this is an intermediate solution to maintain compatibility until some
* upcoming major release (3.0?) brings up changes in packet structure anyway
* in the course of which a dedicated compression field could be spent.
* REVISIT then. */
pkt.transform = pkt.transform | (pkt.compression << (8*sizeof(pkt.transform)-N2N_COMPRESSION_ID_BITLEN));
idx=0;
encode_PACKET(pktbuf, &idx, &cmn, &pkt);
idx += eee->transop.fwd(&eee->transop,
pktbuf+idx, N2N_PKT_BUF_SIZE-idx,
tap_pkt, len, pkt.dstMac);
traceEvent(TRACE_DEBUG, "Encode %u B PACKET [%u B data, %u B overhead] transform %u",
(u_int)idx, (u_int)len, (u_int)(idx-len), tx_transop_idx);
#ifdef MTU_ASSERT_VALUE
{
const u_int eth_udp_overhead = ETH_FRAMESIZE + IP4_MIN_SIZE + UDP_SIZE;
// MTU assertion which avoids fragmentation by N2N
assert(idx + eth_udp_overhead <= MTU_ASSERT_VALUE);
}
#endif
eee->transop.tx_cnt++; /* stats */
send_packet(eee, destMac, pktbuf, idx); /* to peer or supernode */
}
/* ************************************** */
/** Read a single packet from the TAP interface, process it and write out the
* corresponding packet to the cooked socket.
*/
static void readFromTAPSocket(n2n_edge_t * eee) {
/* tun -> remote */
uint8_t eth_pkt[N2N_PKT_BUF_SIZE];
macstr_t mac_buf;
ssize_t len;
#ifdef __ANDROID_NDK__
if (uip_arp_len != 0) {
len = uip_arp_len;
memcpy(eth_pkt, uip_arp_buf, MIN(uip_arp_len, N2N_PKT_BUF_SIZE));
traceEvent(TRACE_DEBUG, "ARP reply packet to send");
}
else
{
#endif /* #ifdef __ANDROID_NDK__ */
len = tuntap_read( &(eee->device), eth_pkt, N2N_PKT_BUF_SIZE );
#ifdef __ANDROID_NDK__
}
#endif /* #ifdef __ANDROID_NDK__ */
if((len <= 0) || (len > N2N_PKT_BUF_SIZE))
{
traceEvent(TRACE_WARNING, "read()=%d [%d/%s]",
(signed int)len, errno, strerror(errno));
}
else
{
const uint8_t * mac = eth_pkt;
traceEvent(TRACE_DEBUG, "### Rx TAP packet (%4d) for %s",
(signed int)len, macaddr_str(mac_buf, mac));
if(eee->conf.drop_multicast &&
(is_ip6_discovery(eth_pkt, len) ||
is_ethMulticast(eth_pkt, len)
)
)
{
traceEvent(TRACE_INFO, "Dropping TX multicast");
}
else
{
send_packet2net(eee, eth_pkt, len);
}
}
}
/* ************************************** */
#ifdef WIN32
struct tunread_arg {
n2n_edge_t *eee;
int *keep_running;
};
static DWORD* tunReadThread(LPVOID lpArg) {
struct tunread_arg *arg = (struct tunread_arg*)lpArg;
while(*arg->keep_running)
readFromTAPSocket(arg->eee);
return((DWORD*)NULL);
}
/* ************************************** */
/** Start a second thread in Windows because TUNTAP interfaces do not expose
* file descriptors. */
static HANDLE startTunReadThread(struct tunread_arg *arg) {
DWORD dwThreadId;
return(CreateThread(NULL, /* security attributes */
0, /* use default stack size */
(LPTHREAD_START_ROUTINE)tunReadThread, /* thread function */
(void*)arg, /* argument to thread function */
0, /* thread creation flags */
&dwThreadId)); /* thread id out */
}
#endif
/* ************************************** */
/** Read a datagram from the main UDP socket to the internet. */
static void readFromIPSocket(n2n_edge_t * eee, int in_sock) {
n2n_common_t cmn; /* common fields in the packet header */
n2n_sock_str_t sockbuf1;
n2n_sock_str_t sockbuf2; /* don't clobber sockbuf1 if writing two addresses to trace */
macstr_t mac_buf1;
macstr_t mac_buf2;
uint8_t udp_buf[N2N_PKT_BUF_SIZE]; /* Compete UDP packet */
ssize_t recvlen;
size_t rem;
size_t idx;
size_t msg_type;
uint8_t from_supernode;
struct sockaddr_in sender_sock;
n2n_sock_t sender;
n2n_sock_t * orig_sender=NULL;
time_t now=0;
size_t i;
i = sizeof(sender_sock);
recvlen = recvfrom(in_sock, udp_buf, N2N_PKT_BUF_SIZE, 0/*flags*/,
(struct sockaddr *)&sender_sock, (socklen_t*)&i);
if(recvlen < 0) {
#ifdef WIN32
if(WSAGetLastError() != WSAECONNRESET)
#endif
{
traceEvent(TRACE_ERROR, "recvfrom() failed %d errno %d (%s)", recvlen, errno, strerror(errno));
#ifdef WIN32
traceEvent(TRACE_ERROR, "WSAGetLastError(): %u", WSAGetLastError());
#endif
}
return; /* failed to receive data from UDP */
}
/* REVISIT: when UDP/IPv6 is supported we will need a flag to indicate which
* IP transport version the packet arrived on. May need to UDP sockets. */
sender.family = AF_INET; /* UDP socket was opened PF_INET v4 */
sender.port = ntohs(sender_sock.sin_port);
memcpy(&(sender.addr.v4), &(sender_sock.sin_addr.s_addr), IPV4_SIZE);
/* The packet may not have an orig_sender socket spec. So default to last
* hop as sender. */
orig_sender=&sender;
traceEvent(TRACE_DEBUG, "### Rx N2N UDP (%d) from %s",
(signed int)recvlen, sock_to_cstr(sockbuf1, &sender));
/* hexdump(udp_buf, recvlen); */
rem = recvlen; /* Counts down bytes of packet to protect against buffer overruns. */
idx = 0; /* marches through packet header as parts are decoded. */
if(decode_common(&cmn, udp_buf, &rem, &idx) < 0)
{
traceEvent(TRACE_ERROR, "Failed to decode common section in N2N_UDP");
return; /* failed to decode packet */
}
now = time(NULL);
msg_type = cmn.pc; /* packet code */
from_supernode= cmn.flags & N2N_FLAGS_FROM_SUPERNODE;
if(0 == memcmp(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE)) {
switch(msg_type) {
case MSG_TYPE_PACKET:
{
/* process PACKET - most frequent so first in list. */
n2n_PACKET_t pkt;
decode_PACKET(&pkt, &cmn, udp_buf, &rem, &idx);
if(is_valid_peer_sock(&pkt.sock))
orig_sender = &(pkt.sock);
if(!from_supernode) {
/* This is a P2P packet from the peer. We purge a pending
* registration towards the possibly nat-ted peer address as we now have
* a valid channel. We still use check_peer_registration_needed in
* handle_PACKET to double check this.
*/
traceEvent(TRACE_DEBUG, "Got P2P packet");
find_and_remove_peer(&eee->pending_peers, pkt.srcMac);
}
traceEvent(TRACE_INFO, "Rx PACKET from %s (sender=%s) [%u B]",
sock_to_cstr(sockbuf1, &sender),
sock_to_cstr(sockbuf2, orig_sender),
recvlen);
handle_PACKET(eee, &cmn, &pkt, orig_sender, udp_buf+idx, recvlen-idx);
break;
}
case MSG_TYPE_REGISTER:
{
/* Another edge is registering with us */
n2n_REGISTER_t reg;
n2n_mac_t null_mac = { '\0' };
int via_multicast;
decode_REGISTER(&reg, &cmn, udp_buf, &rem, &idx);
if(is_valid_peer_sock(&reg.sock))
orig_sender = &(reg.sock);
via_multicast = !memcmp(reg.dstMac, null_mac, 6);
if(via_multicast && !memcmp(reg.srcMac, eee->device.mac_addr, 6)) {
traceEvent(TRACE_DEBUG, "Skipping REGISTER from self");
break;
}
if(!via_multicast && memcmp(reg.dstMac, eee->device.mac_addr, 6)) {
traceEvent(TRACE_DEBUG, "Skipping REGISTER for other peer");
break;
}
if(!from_supernode) {
/* This is a P2P registration from the peer. We purge a pending
* registration towards the possibly nat-ted peer address as we now have
* a valid channel. We still use check_peer_registration_needed below
* to double check this.
*/
traceEvent(TRACE_DEBUG, "Got P2P register");
find_and_remove_peer(&eee->pending_peers, reg.srcMac);
/* NOTE: only ACK to peers */
send_register_ack(eee, orig_sender, &reg);
}
traceEvent(TRACE_INFO, "Rx REGISTER src=%s dst=%s from peer %s (%s)",
macaddr_str(mac_buf1, reg.srcMac),
macaddr_str(mac_buf2, reg.dstMac),
sock_to_cstr(sockbuf1, &sender),
sock_to_cstr(sockbuf2, orig_sender));
check_peer_registration_needed(eee, from_supernode, reg.srcMac, orig_sender);
break;
}
case MSG_TYPE_REGISTER_ACK:
{
/* Peer edge is acknowledging our register request */
n2n_REGISTER_ACK_t ra;
decode_REGISTER_ACK(&ra, &cmn, udp_buf, &rem, &idx);
if(is_valid_peer_sock(&ra.sock))
orig_sender = &(ra.sock);
traceEvent(TRACE_INFO, "Rx REGISTER_ACK src=%s dst=%s from peer %s (%s)",
macaddr_str(mac_buf1, ra.srcMac),
macaddr_str(mac_buf2, ra.dstMac),
sock_to_cstr(sockbuf1, &sender),
sock_to_cstr(sockbuf2, orig_sender));
peer_set_p2p_confirmed(eee, ra.srcMac, &sender, now);
break;
}
case MSG_TYPE_REGISTER_SUPER_ACK:
{
n2n_REGISTER_SUPER_ACK_t ra;
if(eee->sn_wait)
{
decode_REGISTER_SUPER_ACK(&ra, &cmn, udp_buf, &rem, &idx);
if(is_valid_peer_sock(&ra.sock))
orig_sender = &(ra.sock);
traceEvent(TRACE_INFO, "Rx REGISTER_SUPER_ACK myMAC=%s [%s] (external %s). Attempts %u",
macaddr_str(mac_buf1, ra.edgeMac),
sock_to_cstr(sockbuf1, &sender),
sock_to_cstr(sockbuf2, orig_sender),
(unsigned int)eee->sup_attempts);
if(0 == memcmp(ra.cookie, eee->last_cookie, N2N_COOKIE_SIZE))
{
if(ra.num_sn > 0)
{
traceEvent(TRACE_NORMAL, "Rx REGISTER_SUPER_ACK backup supernode at %s",
sock_to_cstr(sockbuf1, &(ra.sn_bak)));
}
eee->last_sup = now;
eee->sn_wait=0;
eee->sup_attempts = N2N_EDGE_SUP_ATTEMPTS; /* refresh because we got a response */
/* NOTE: the register_interval should be chosen by the edge node
* based on its NAT configuration. */
//eee->conf.register_interval = ra.lifetime;
}
else
{
traceEvent(TRACE_INFO, "Rx REGISTER_SUPER_ACK with wrong or old cookie.");
}
}
else
{
traceEvent(TRACE_INFO, "Rx REGISTER_SUPER_ACK with no outstanding REGISTER_SUPER.");
}
break;
} case MSG_TYPE_PEER_INFO: {
n2n_PEER_INFO_t pi;
struct peer_info * scan;
decode_PEER_INFO( &pi, &cmn, udp_buf, &rem, &idx );
if(!is_valid_peer_sock(&pi.sock)) {
traceEvent(TRACE_DEBUG, "Skip invalid PEER_INFO %s [%s]",
sock_to_cstr(sockbuf1, &pi.sock),
macaddr_str(mac_buf1, pi.mac) );
break;
}
HASH_FIND_PEER(eee->pending_peers, pi.mac, scan);
if (scan) {
scan->sock = pi.sock;
traceEvent(TRACE_INFO, "Rx PEER_INFO for %s: is at %s",
macaddr_str(mac_buf1, pi.mac),
sock_to_cstr(sockbuf1, &pi.sock));
send_register(eee, &scan->sock, scan->mac_addr);
} else {
traceEvent(TRACE_INFO, "Rx PEER_INFO unknown peer %s",
macaddr_str(mac_buf1, pi.mac) );
}
break;
}
default:
/* Not a known message type */
traceEvent(TRACE_WARNING, "Unable to handle packet type %d: ignored", (signed int)msg_type);
return;
} /* switch(msg_type) */
} else if(from_supernode) /* if (community match) */
traceEvent(TRACE_WARNING, "Received packet with unknown community");
else
traceEvent(TRACE_INFO, "Ignoring packet with unknown community");
}
/* ************************************** */
void print_edge_stats(const n2n_edge_t *eee) {
const struct n2n_edge_stats *s = &eee->stats;
traceEvent(TRACE_NORMAL, "**********************************");
traceEvent(TRACE_NORMAL, "Packet stats:");
traceEvent(TRACE_NORMAL, " TX P2P: %u pkts", s->tx_p2p);
traceEvent(TRACE_NORMAL, " RX P2P: %u pkts", s->rx_p2p);
traceEvent(TRACE_NORMAL, " TX Supernode: %u pkts (%u broadcast)", s->tx_sup, s->tx_sup_broadcast);
traceEvent(TRACE_NORMAL, " RX Supernode: %u pkts (%u broadcast)", s->rx_sup, s->rx_sup_broadcast);
traceEvent(TRACE_NORMAL, "**********************************");
}
/* ************************************** */
int run_edge_loop(n2n_edge_t * eee, int *keep_running) {
size_t numPurged;
time_t lastIfaceCheck=0;
time_t lastTransop=0;
time_t last_purge_known = 0;
time_t last_purge_pending = 0;
#ifdef __ANDROID_NDK__
time_t lastArpPeriod=0;
#endif
#ifdef WIN32
struct tunread_arg arg;
arg.eee = eee;
arg.keep_running = keep_running;
HANDLE tun_read_thread = startTunReadThread(&arg);
#endif
*keep_running = 1;
update_supernode_reg(eee, time(NULL));
/* Main loop
*
* select() is used to wait for input on either the TAP fd or the UDP/TCP
* socket. When input is present the data is read and processed by either
* readFromIPSocket() or readFromTAPSocket()
*/
while(*keep_running) {
int rc, max_sock = 0;
fd_set socket_mask;
struct timeval wait_time;
time_t nowTime;
FD_ZERO(&socket_mask);
FD_SET(eee->udp_sock, &socket_mask);
FD_SET(eee->udp_mgmt_sock, &socket_mask);
max_sock = max(eee->udp_sock, eee->udp_mgmt_sock);
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
FD_SET(eee->udp_multicast_sock, &socket_mask);
max_sock = max(eee->udp_sock, eee->udp_multicast_sock);
#endif
#ifndef WIN32
FD_SET(eee->device.fd, &socket_mask);
max_sock = max(max_sock, eee->device.fd);
#endif
wait_time.tv_sec = SOCKET_TIMEOUT_INTERVAL_SECS; wait_time.tv_usec = 0;
rc = select(max_sock+1, &socket_mask, NULL, NULL, &wait_time);
nowTime=time(NULL);
/* Make sure ciphers are updated before the packet is treated. */
if((nowTime - lastTransop) > TRANSOP_TICK_INTERVAL) {
lastTransop = nowTime;
eee->transop.tick(&eee->transop, nowTime);
}
if(rc > 0) {
/* Any or all of the FDs could have input; check them all. */
if(FD_ISSET(eee->udp_sock, &socket_mask)) {
/* Read a cooked socket from the internet socket (unicast). Writes on the TAP
* socket. */
readFromIPSocket(eee, eee->udp_sock);
}
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
if(FD_ISSET(eee->udp_multicast_sock, &socket_mask)) {
/* Read a cooked socket from the internet socket (multicast). Writes on the TAP
* socket. */
traceEvent(TRACE_DEBUG, "Received packet from multicast socket");
readFromIPSocket(eee, eee->udp_multicast_sock);
}
#endif
#ifdef __ANDROID_NDK__
if (uip_arp_len != 0) {
readFromTAPSocket(eee);
uip_arp_len = 0;
}
#endif /* #ifdef __ANDROID_NDK__ */
if(FD_ISSET(eee->udp_mgmt_sock, &socket_mask)) {
/* Read a cooked socket from the internet socket. Writes on the TAP
* socket. */
readFromMgmtSocket(eee, keep_running);
}
#ifndef WIN32
if(FD_ISSET(eee->device.fd, &socket_mask)) {
/* Read an ethernet frame from the TAP socket. Write on the IP
* socket. */
readFromTAPSocket(eee);
}
#endif
}
/* Finished processing select data. */
update_supernode_reg(eee, nowTime);
numPurged = purge_expired_registrations(&eee->known_peers, &last_purge_known);
numPurged += purge_expired_registrations(&eee->pending_peers, &last_purge_pending);
if(numPurged > 0) {
traceEvent(TRACE_INFO, "%u peers removed. now: pending=%u, operational=%u",
numPurged,
HASH_COUNT(eee->pending_peers),
HASH_COUNT(eee->known_peers));
}
if(eee->conf.dyn_ip_mode &&
((nowTime - lastIfaceCheck) > IFACE_UPDATE_INTERVAL)) {
traceEvent(TRACE_NORMAL, "Re-checking dynamic IP address.");
tuntap_get_address(&(eee->device));
lastIfaceCheck = nowTime;
}
#ifdef __ANDROID_NDK__
if ((nowTime - lastArpPeriod) > ARP_PERIOD_INTERVAL) {
uip_arp_timer();
lastArpPeriod = nowTime;
}
#endif /* #ifdef __ANDROID_NDK__ */
} /* while */
#ifdef WIN32
WaitForSingleObject(tun_read_thread, INFINITE);
#endif
send_deregister(eee, &(eee->supernode));
closesocket(eee->udp_sock);
return(0);
}
/* ************************************** */
/** Deinitialise the edge and deallocate any owned memory. */
void edge_term(n2n_edge_t * eee) {
if(eee->udp_sock >= 0)
closesocket(eee->udp_sock);
if(eee->udp_mgmt_sock >= 0)
closesocket(eee->udp_mgmt_sock);
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
if(eee->udp_multicast_sock >= 0)
closesocket(eee->udp_multicast_sock);
#endif
clear_peer_list(&eee->pending_peers);
clear_peer_list(&eee->known_peers);
eee->transop.deinit(&eee->transop);
edge_cleanup_routes(eee);
free(eee);
}
/* ************************************** */
static int edge_init_sockets(n2n_edge_t *eee, int udp_local_port, int mgmt_port, uint8_t tos) {
int sockopt;
if(udp_local_port > 0)
traceEvent(TRACE_NORMAL, "Binding to local port %d", udp_local_port);
eee->udp_sock = open_socket(udp_local_port, 1 /* bind ANY */);
if(eee->udp_sock < 0) {
traceEvent(TRACE_ERROR, "Failed to bind main UDP port %u", udp_local_port);
return(-1);
}
if(tos) {
/* https://www.tucny.com/Home/dscp-tos */
sockopt = tos;
if(setsockopt(eee->udp_sock, IPPROTO_IP, IP_TOS, &sockopt, sizeof(sockopt)) == 0)
traceEvent(TRACE_NORMAL, "TOS set to 0x%x", tos);
else
traceEvent(TRACE_ERROR, "Could not set TOS 0x%x[%d]: %s", tos, errno, strerror(errno));
}
#ifdef IP_PMTUDISC_DO
sockopt = (eee->conf.disable_pmtu_discovery) ? IP_PMTUDISC_DONT : IP_PMTUDISC_DO;
if(setsockopt(eee->udp_sock, IPPROTO_IP, IP_MTU_DISCOVER, &sockopt, sizeof(sockopt)) < 0)
traceEvent(TRACE_WARNING, "Could not %s PMTU discovery[%d]: %s",
(eee->conf.disable_pmtu_discovery) ? "disable" : "enable", errno, strerror(errno));
else
traceEvent(TRACE_DEBUG, "PMTU discovery %s", (eee->conf.disable_pmtu_discovery) ? "disabled" : "enabled");
#endif
eee->udp_mgmt_sock = open_socket(mgmt_port, 0 /* bind LOOPBACK */);
if(eee->udp_mgmt_sock < 0) {
traceEvent(TRACE_ERROR, "Failed to bind management UDP port %u", mgmt_port);
return(-2);
}
#ifndef SKIP_MULTICAST_PEERS_DISCOVERY
/* Populate the multicast group for local edge */
eee->multicast_peer.family = AF_INET;
eee->multicast_peer.port = N2N_MULTICAST_PORT;
eee->multicast_peer.addr.v4[0] = 224; /* N2N_MULTICAST_GROUP */
eee->multicast_peer.addr.v4[1] = 0;
eee->multicast_peer.addr.v4[2] = 0;
eee->multicast_peer.addr.v4[3] = 68;
eee->udp_multicast_sock = open_socket(N2N_MULTICAST_PORT, 1 /* bind ANY */);
if(eee->udp_multicast_sock < 0)
return(-3);
else {
u_int enable_reuse = 1;
/* allow multiple sockets to use the same PORT number */
setsockopt(eee->udp_multicast_sock, SOL_SOCKET, SO_REUSEADDR, (char *)&enable_reuse, sizeof(enable_reuse));
#ifdef SO_REUSEPORT /* no SO_REUSEPORT in Windows / old linux versions */
setsockopt(eee->udp_multicast_sock, SOL_SOCKET, SO_REUSEPORT, &enable_reuse, sizeof(enable_reuse));
#endif
}
#endif
return(0);
}
/* ************************************** */
#ifdef __linux__
static uint32_t get_gateway_ip() {
FILE *fd;
char *token = NULL;
char *gateway_ip_str = NULL;
char buf[256];
uint32_t gateway = 0;
if(!(fd = fopen("/proc/net/route", "r")))
return(0);
while(fgets(buf, sizeof(buf), fd)) {
if(strtok(buf, "\t") && (token = strtok(NULL, "\t")) && (!strcmp(token, "00000000"))) {
token = strtok(NULL, "\t");
if(token) {
struct in_addr addr;
addr.s_addr = strtoul(token, NULL, 16);
gateway_ip_str = inet_ntoa(addr);
if(gateway_ip_str) {
gateway = addr.s_addr;
break;
}
}
}
}
fclose(fd);
return(gateway);
}
static char* route_cmd_to_str(int cmd, const n2n_route_t *route, char *buf, size_t bufsize) {
const char *cmd_str;
struct in_addr addr;
char netbuf[64], gwbuf[64];
switch(cmd) {
case RTM_NEWROUTE:
cmd_str = "Add";
break;
case RTM_DELROUTE:
cmd_str = "Delete";
break;
default:
cmd_str = "?";
}
addr.s_addr = route->net_addr;
inet_ntop(AF_INET, &addr, netbuf, sizeof(netbuf));
addr.s_addr = route->gateway;
inet_ntop(AF_INET, &addr, gwbuf, sizeof(gwbuf));
snprintf(buf, bufsize, "%s %s/%d via %s", cmd_str, netbuf, route->net_bitlen, gwbuf);
return(buf);
}
/* Adapted from https://olegkutkov.me/2019/08/29/modifying-linux-network-routes-using-netlink/ */
#define NLMSG_TAIL(nmsg) \
((struct rtattr *) (((char *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
/* Add new data to rtattr */
static int rtattr_add(struct nlmsghdr *n, int maxlen, int type, const void *data, int alen)
{
int len = RTA_LENGTH(alen);
struct rtattr *rta;
if(NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
traceEvent(TRACE_ERROR, "rtattr_add error: message exceeded bound of %d\n", maxlen);
return -1;
}
rta = NLMSG_TAIL(n);
rta->rta_type = type;
rta->rta_len = len;
if(alen)
memcpy(RTA_DATA(rta), data, alen);
n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
return 0;
}
static int routectl(int cmd, int flags, n2n_route_t *route, int if_idx) {
int rv = -1;
int rv2;
char nl_buf[8192]; /* >= 8192 to avoid truncation, see "man 7 netlink" */
char route_buf[256];
struct iovec iov;
struct msghdr msg;
struct sockaddr_nl sa;
uint8_t read_reply = 1;
int nl_sock;
struct {
struct nlmsghdr n;
struct rtmsg r;
char buf[4096];
} nl_request;
if((nl_sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) == -1) {
traceEvent(TRACE_ERROR, "netlink socket creation failed [%d]: %s", errno, strerror(errno));
return(-1);
}
/* Subscribe to route change events */
iov.iov_base = nl_buf;
iov.iov_len = sizeof(nl_buf);
memset(&sa, 0, sizeof(sa));
sa.nl_family = PF_NETLINK;
sa.nl_groups = RTMGRP_IPV4_ROUTE | RTMGRP_NOTIFY;
sa.nl_pid = getpid();
memset(&msg, 0, sizeof(msg));
msg.msg_name = &sa;
msg.msg_namelen = sizeof(sa);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
/* Subscribe to route events */
if(bind(nl_sock, (struct sockaddr*)&sa, sizeof(sa)) == -1) {
traceEvent(TRACE_ERROR, "netlink socket bind failed [%d]: %s", errno, strerror(errno));
goto out;
}
/* Initialize request structure */
memset(&nl_request, 0, sizeof(nl_request));
nl_request.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
nl_request.n.nlmsg_flags = NLM_F_REQUEST | flags;
nl_request.n.nlmsg_type = cmd;
nl_request.r.rtm_family = AF_INET;
nl_request.r.rtm_table = RT_TABLE_MAIN;
nl_request.r.rtm_scope = RT_SCOPE_NOWHERE;
/* Set additional flags if NOT deleting route */
if(cmd != RTM_DELROUTE) {
nl_request.r.rtm_protocol = RTPROT_BOOT;
nl_request.r.rtm_type = RTN_UNICAST;
}
nl_request.r.rtm_family = AF_INET;
nl_request.r.rtm_dst_len = route->net_bitlen;
/* Select scope, for simplicity we supports here only IPv6 and IPv4 */
if(nl_request.r.rtm_family == AF_INET6)
nl_request.r.rtm_scope = RT_SCOPE_UNIVERSE;
else
nl_request.r.rtm_scope = RT_SCOPE_LINK;
/* Set gateway */
if(route->net_bitlen) {
if(rtattr_add(&nl_request.n, sizeof(nl_request), RTA_GATEWAY, &route->gateway, 4) < 0)
goto out;
nl_request.r.rtm_scope = 0;
nl_request.r.rtm_family = AF_INET;
}
/* Don't set destination and interface in case of default gateways */
if(route->net_bitlen) {
/* Set destination network */
if(rtattr_add(&nl_request.n, sizeof(nl_request), /*RTA_NEWDST*/ RTA_DST, &route->net_addr, 4) < 0)
goto out;
/* Set interface */
if(if_idx > 0) {
if(rtattr_add(&nl_request.n, sizeof(nl_request), RTA_OIF, &if_idx, sizeof(int)) < 0)
goto out;
}
}
/* Send message to the netlink */
if((rv2 = send(nl_sock, &nl_request, sizeof(nl_request), 0)) != sizeof(nl_request)) {
traceEvent(TRACE_ERROR, "netlink send failed [%d]: %s", errno, strerror(errno));
goto out;
}
/* Wait for the route notification. Assume that the first reply we get is the correct one. */
traceEvent(TRACE_DEBUG, "waiting for netlink response...");
while(read_reply) {
ssize_t len = recvmsg(nl_sock, &msg, 0);
struct nlmsghdr *nh;
for(nh = (struct nlmsghdr *)nl_buf; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
/* Stop after the first reply */
read_reply = 0;
if(nh->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = NLMSG_DATA(nh);
int errcode = err->error;
if(errcode < 0)
errcode = -errcode;
/* Ignore EEXIST as existing rules are ok */
if(errcode != EEXIST) {
traceEvent(TRACE_ERROR, "[err=%d] route: %s", errcode, route_cmd_to_str(cmd, route, route_buf, sizeof(route_buf)));
goto out;
}
}
if(nh->nlmsg_type == NLMSG_DONE)
break;
if(nh->nlmsg_type == cmd) {
traceEvent(TRACE_DEBUG, "Found netlink reply");
break;
}
}
}
traceEvent(TRACE_DEBUG, route_cmd_to_str(cmd, route, route_buf, sizeof(route_buf)));
rv = 0;
out:
close(nl_sock);
return(rv);
}
#endif
/* Add the user-provided routes to the linux routing table. Network routes
* are bound to the n2n TAP device, so they are automatically removed when
* the TAP device is destroyed. */
static int edge_init_routes(n2n_edge_t *eee, n2n_route_t *routes, uint16_t num_routes) {
#ifdef __linux__
int i;
for(i=0; i<num_routes; i++) {
n2n_route_t *route = &routes[i];
if((route->net_addr == 0) && (route->net_bitlen == 0)) {
/* This is a default gateway rule. We need to:
*
* 1. Add a route to the supernode via the host internet gateway
* 2. Add the new default gateway route
*
* Instead of modifying the system default gateway, we use the trick
* of adding a route to the 0.0.0.0/1 network, which takes precedence
* over the default gateway (0.0.0.0/0). This leaves the default
* gateway unchanged so that after n2n is stopped the cleanup is
* easier.
*/
n2n_sock_t sn;
n2n_route_t custom_route;
uint32_t *a;
if(eee->sn_route_to_clean) {
traceEvent(TRACE_ERROR, "Only one default gateway route allowed");
return(-1);
}
if(eee->conf.sn_num != 1) {
traceEvent(TRACE_ERROR, "Only one supernode supported with routes");
return(-1);
}
if(supernode2addr(&sn, eee->conf.sn_ip_array[0]) < 0)
return(-1);
if(sn.family != AF_INET) {
traceEvent(TRACE_ERROR, "Only IPv4 routes supported");
return(-1);
}
a = (u_int32_t*)sn.addr.v4;
custom_route.net_addr = *a;
custom_route.net_bitlen = 32;
custom_route.gateway = get_gateway_ip();
if(!custom_route.gateway) {
traceEvent(TRACE_ERROR, "could not determine the gateway IP address");
return(-1);
}
/* ip route add supernode via internet_gateway */
if(routectl(RTM_NEWROUTE, NLM_F_CREATE | NLM_F_EXCL, &custom_route, -1) < 0)
return(-1);
/* Save the route to delete it when n2n is stopped */
eee->sn_route_to_clean = calloc(1, sizeof(n2n_route_t));
/* Store a copy of the rules into the runtime to delete it during shutdown */
if(eee->sn_route_to_clean)
*eee->sn_route_to_clean = custom_route;
/* ip route add 0.0.0.0/1 via n2n_gateway */
custom_route.net_addr = 0;
custom_route.net_bitlen = 1;
custom_route.gateway = route->gateway;
if(routectl(RTM_NEWROUTE, NLM_F_CREATE | NLM_F_EXCL, &custom_route, eee->device.if_idx) < 0)
return(-1);
} else {
/* ip route add net via n2n_gateway */
if(routectl(RTM_NEWROUTE, NLM_F_CREATE | NLM_F_EXCL, route, eee->device.if_idx) < 0)
return(-1);
}
}
#endif
return(0);
}
/* ************************************** */
static void edge_cleanup_routes(n2n_edge_t *eee) {
#ifdef __linux__
if(eee->sn_route_to_clean) {
/* ip route del supernode via internet_gateway */
routectl(RTM_DELROUTE, 0, eee->sn_route_to_clean, -1);
free(eee->sn_route_to_clean);
}
#endif
}
/* ************************************** */
void edge_init_conf_defaults(n2n_edge_conf_t *conf) {
memset(conf, 0, sizeof(*conf));
conf->local_port = 0 /* any port */;
conf->mgmt_port = N2N_EDGE_MGMT_PORT; /* 5644 by default */
conf->transop_id = N2N_TRANSFORM_ID_NULL;
conf->compression = N2N_COMPRESSION_ID_NONE;
conf->drop_multicast = 1;
conf->allow_p2p = 1;
conf->disable_pmtu_discovery = 1;
conf->register_interval = REGISTER_SUPER_INTERVAL_DFL;
if(getenv("N2N_KEY")) {
conf->encrypt_key = strdup(getenv("N2N_KEY"));
conf->transop_id = N2N_TRANSFORM_ID_TWOFISH;
}
}
/* ************************************** */
void edge_term_conf(n2n_edge_conf_t *conf) {
if(conf->routes) free(conf->routes);
}
/* ************************************** */
const n2n_edge_conf_t* edge_get_conf(const n2n_edge_t *eee) {
return(&eee->conf);
}
/* ************************************** */
int edge_conf_add_supernode(n2n_edge_conf_t *conf, const char *ip_and_port) {
if(conf->sn_num >= N2N_EDGE_NUM_SUPERNODES)
return(-1);
strncpy((conf->sn_ip_array[conf->sn_num]), ip_and_port, N2N_EDGE_SN_HOST_SIZE);
traceEvent(TRACE_NORMAL, "Adding supernode[%u] = %s", (unsigned int)conf->sn_num, (conf->sn_ip_array[conf->sn_num]));
conf->sn_num++;
return(0);
}
/* ************************************** */
int quick_edge_init(char *device_name, char *community_name,
char *encrypt_key, char *device_mac,
char *local_ip_address,
char *supernode_ip_address_port,
int *keep_on_running) {
tuntap_dev tuntap;
n2n_edge_t *eee;
n2n_edge_conf_t conf;
int rv;
/* Setup the configuration */
edge_init_conf_defaults(&conf);
conf.encrypt_key = encrypt_key;
conf.transop_id = N2N_TRANSFORM_ID_TWOFISH;
snprintf((char*)conf.community_name, sizeof(conf.community_name), "%s", community_name);
edge_conf_add_supernode(&conf, supernode_ip_address_port);
/* Validate configuration */
if(edge_verify_conf(&conf) != 0)
return(-1);
/* Open the tuntap device */
if(tuntap_open(&tuntap, device_name, "static",
local_ip_address, "255.255.255.0",
device_mac, DEFAULT_MTU) < 0)
return(-2);
/* Init edge */
if((eee = edge_init(&tuntap, &conf, &rv)) == NULL)
goto quick_edge_init_end;
rv = run_edge_loop(eee, keep_on_running);
edge_term(eee);
edge_term_conf(&conf);
quick_edge_init_end:
tuntap_close(&tuntap);
return(rv);
}
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